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ORNUM-6589

OAK RIDGE NATIONAL LABORATORY Metals and Ceramics Division n LOCKHEED MARTIN/ History 1946-l 996

contributors

The story of the Metals and Ceramics Division is the story of its people and the work they did, as well as the projects that resided in the Division or that the Division contributed to. Many people wrote and rewrote reams of paper trying to pull this document together, and those who wrote various sections (whether used or not) are listed below.

Those who are not listed are the rest of you;you rummaged around in your memories to provide facts and anecdotes, typed documents for others, proofread drafts, and so on. And mainly, you did the outstanding work that gave this Division a story to tell. Thanks to all of you for 50 interesting and productive years.

September 30, I997

Douglas E Craig, Director Metals and Ceramics Division Oak Ridge National Laboratory

Thanks to each of these writers and editors:

G. M. Adamson S. A. David P H. Miller C. A. Baldwin J. R. DiStefano R. K. Nanstad R. J. Beaver R. J. Gray S. Peterson E. E. Bloom M. J. Kania P L Rittenhouse E. S. Bomar I? R. Kasten J. D. Sease R. A. Bradley E.A. Kenik G. M. Slaughter D.A. Canonico R. W. Knight C. J. Sparks J.V. Cathcart W. D. Manly K. Spence R. E. Clausing L K. Mansur I? A.Teague J. H. Coobs H. E. McCoy V. J.Tennery R. H. Cooper C. J. McHargue J. R. Weir, Jr. J. E. Cunningham

table of contents

introduction ...... I

background ...... 3 radiation materials science in m&c...... 4 metallographic services ...... 12 fundamental and applied research...... 19 the roofs over our heads ...... 30

I 946- 1960: reactor material years ...... 37 ornl reactor ...... 38 materials testing and tank-type reactors ...... 42 aircraft nuclear propulsion-aircraft reactor test...... 48 homogeneous reactor project ...... 53

I 950-I 975: reactor project years ...... 57 army package power reactor ...... 58 geneva conference display reactor...... 60 metallurgy...... : ...... 62 fusion materials ...... 63 gas-cooled reactors ...... 71 space nuclear programs ...... 78 advanced test reactor ...... 82 molten-salt power reactors ...... 83 high flux isotope reactor ...... 86 fabricating targets for the high flux isotope reactor...... 92 heavy-section steel technology and irradiation ...... 94 liquid-metal fast breeder reactor ...... 99

l975- 1996: diversification and the high-technology years...... 103 structure and properties of surfaces ...... 104 fossil energy program ...... IO6 synchrotr-on radiation &wnline ...... IO9 shared research equipment program ...... I I I * electron beam welder...... I I3 the high temperature materials laboratory ...... I I4 multiple ion irradiation ...... I I8 conservation materials program ...... 120

appendix 1. chronology of division directors ...... 125

appendix 2. selected photographs of division staff ...... I 3 I .

introduction

The division was formed in 1946 at the grams directly related to a specific suggestion of Dr. Eugene P. Wigner to reactor(s) being designed or built. The 2 attack the problem of the distortion of Division (Metals and Ceramics) con- graphite in the early reactors due to sisted of 204 staff members in 1973 exposure to reactor , and the when James R. Weir, Jr., became Direc- consequent radiation damage. It was tor. This was the period of the oil em- called the Metallurgy Division and bargo, the formation of the Energy assembled the metallurgical and solid Research and Development Administra- state physics activities of the time tion (ERDA) by combining the Atomic which were not directly related to Energy Commission (AEC) with the nuclear weapons production. William Office of Coal Research, and subse- A. Johnson, a Westinghouse employee, quent formation of the Department of was named Division Director in 1946. Energy (DOE). The diversification pro- In 1949 he was replaced by John H cess continued when James 0. Stiegler Frye Jr. when the Division consisted of became Director in 1984, partially as a 45 people. He was director during most result of the pressure of legislation of what is called the Reactor Project encouraging the national laboratories Years until 1973 and his retirement. to work with U.S. industries on their During this period the Division evolved problems. During that time the Division into three organizational areas: basic staff grew from 265 to 330. Douglas F. research, applied research in nuclear Craig became Director in 1992. reactor materials, and reactor pro-

introduction

radiation materials science in m&c

That the various forms of radiation began to determine the influence of emanating from radioactive isotopes or these effect. 4 from the nuclei of fissioning would produce damage or change the Commercial alloys hardened and form of the materials through which decreased in ductility in a way the radiation passed was known much qualitatively similar to the earlier before the and the observations in pure metals. This genesis of Oak Ridge. “damage,” however, tended to disappear as the temperature of the alloy was Immediately after the war, some of the raised into the range useful in power scientific staff of the project began plants. publishing in the scientific literature speculations, mainly based on A different form of damage of theoretical considerations, about the technological importance was potential deleterious effects on the discovered almost simultaneously in materials that might be used in 1956 at ORNL and at the Harwell constructing nuclear power plants. Laboratory in England. Bubbles of formed in the alloys as oak ridge involved in neutrons released alpha particles studying radiation (helium nuclei) from the chemical effects elements within the alloy. In addition, changes occurred in the chemical The recognition of these possible reactions in the alloys and swelling effects on materials led to experimental occurred during exposure to reactor and theoretical programs at the Atomic neutrons at high temperatures. Energy Commission laboratories throughout the country, including what is radiation ORNL. Initially, the Chemistry Division materials science? began to study the effects of gamma rays and neutrons on ceramics, and Radiation Effects, or more accurately, the Physics of Solids group (then part Radiation Materials Science is a broad of the Metallurgy Division) began term covering the phenomena that theoretical and experimental work on occur in materials exposed to radiation. the effects of neutrons on metals. The field has been built since the 1940s. Oak Ridge National Laboratory During the early 195Os, it was and, in particular, the Metals and recognized that these property changes Ceramics Division has played a would have significant effects on the dominant role in the creation and design of nuclear power plants. The advancement of this field. The work can Metals and Ceramics Division then be visualized in three complementary activities.

background ,.

l Materials Science-This work ,con- amorphous. These anomalies were later sists of characterizing and under- explained as the result of irradiation 5 standing radiation effects phenom- over geological times by decay products ena; learning about radiation- of the naturally radioactive elements induced defects and, through them, uranium and thorium contained in the more about the basic properties of minerals. the materials in which they occur; The radiation effects field got its real and using radiation as a tool to start, however, in the 20th century explore the behavior of materials. during the Manhattan Project. Some 50 . Nuclear Materials Technology-This years ago, Eugene P. Wigner at the activity exists because many struc- Metallurgical Laboratory at the tural materials intended for use in University of realized the fission and fusion reactors are theoretical possibility of displacing vulnerable to radiation induced atoms by irradiation with neutrons. degradation of properties; selecting, Colleagues at Clinton Laboratories modifying and designing materials (later ORNL) Metallurgy Division that are resistant to radiation dam- carried out experiments in the Graphite age, with properties tailored to Reactor to test the idea. A quote from fission and fusion reactor applica- Wigner’s 1946 paper “Theoretical tions. Physics in the Metallurgical Laboratory in Chicago,” (Journal of Applied Physics . New Materials and Properties- 17) also marks the beginning of the Because the capability to irradiate field at ORNL. “The matter has great materials is a dimension of materi- scientific interest because pile als science, like the capability of irradiations should permit the artificial change temperature, virtually every formation of displacements in definite property and process in any class of numbers and a study of the effect of materials can be affected; enhanc- these on thermal and electrical ing materials performance in the conductivity, tensile strength, ductility, wide range of materials technology etc., as demanded by the theory.” applications. As a result, with the birth of the historical sketch Clinton Laboratories Metallurgy Division in 1946, which eventually Some effects of irradiation on solids became ORNL’s Metals and Ceramics were first observed in the 19th century. Division, a radiation effects program Certain minerals known to have came into being. In the early years, externally crystalline shapes were scientific understanding of radiation found to be internally glass-like, or effects was very elementary; much of

background the work involved examining various other, leading to no permanent changes properties by all available in the material. Designers who are measurement techniques. Over the developing radiation-resistant alloys years, researchers used the Graphite seek to maximize this effect. More Reactor, the Bulk Shielding Reactor, often, however, drastic changes in and the Oak Ridge Research Reactor to properties occur as a result of irradiate materials. microstructural changes - such as the formation of dislocation loops or radiation effects cavities - or changes in local composition - such as separation of an Over the years, Division researchers alloy’s constituents. have examined three types of property changes and their underlying physical One of the most significant radiation mechanisms: swelling, creep, and effects is swelling. This occurs when embrittlement. These property changes cavities, which result from the are caused by defects at the atomic aggregation of vacancies, form a level - “vacancies” (where an atom has volume that shows up as macroscopic been moved out of its space) and swelling of the material. Alloys “interstitials” (where the atom has been irradiated to high doses can, as a result moved into a space not its own). These of swelling, become so brittle that its defects are induced by being irradiated ductility is reduced from tens to only with energetic particles. This tenths of a percent or less. Irradiation irradiation could happen both through creep, another radiation effect generally reactor neutrons, such as in fission occurs in materials that are stressed and fusion reactors, and accelerator during irradiation. This shape change ions, such as in mechanistic studies in the material can exceed the shape and ion beam processing. change induced by thermal creep.

One energetic or ion can metallurgy division’s displace an atom by “knocking” it out role of its place, which subsequently displaces other atoms; this effect is Alloys not designed to resist the effect much like that of knocking over a row of neutron irradiation are generally of dominoes. The migration and inadequate for use in fission and fusion interaction of these defects eventually reactors. Because of that, the Atomic can produce permanent changes in the Energy Commission mounted large- structure and composition of the scale efforts to design alloys for material. irradiation performance. The Metallurgy Division, and later the Occasionally, vacancies and Metals and Ceramics Division, has interstitials may recombine with each background played an important role in that The problem was solved by alloying research. In fact, the principles applied with small amounts of titanium, which 7 to improve alloy design have been tied up the in the matrix and derived largely from basic studies of the kept helium out of the boundaries. Jim physical mechanisms and kinetics of Weir was prominent in these efforts to irradiated materials. improve mechanical properties by microalloying; for his work, he received In 1950, the Metallurgy Division’s the Department of Energy’s radiation effects groups, led by the late E. 0. Lawrence Memorial Award in Doug Billington, became the Solid State 1973. After he became division director Division, whose main purpose was in 1973, the Division built up a large radiation effects research. Later, Fred effort in radiation effects. Young, now retired associate director of the Solid State Division, was active in In the 197Os, the division developed influencing fundamental studies .in the aggressive programs for research in field. Later, the Metals and Ceramics radiation effects under Jim Stiegler and Division reentered the field because of Everett Bloom. These programs covered the emerging technological need for three areas: alloy development for reactor materials resistant to neutron liquid metal cooled fast reactor irradiation. Since that time, the structures, alloy development for fusion Division has been involved in reactor applications, and basic developing structural and fuel research on the physical mechanisms materials with appropriate irradiation of radiation effects. At the same time, properties for about two dozen different efforts were mounted in other._,. - _ reactors. countries, especially England, France, Japan, Germany, and the Soviet Union. In 1953, the Division was involve,d with the project to develop a As of this writing the main efforts in for aircraft propulsion; such a reactor radiation effects in the Metals and required high-temperature Ceramics Division are centered on performance. A high-temperature microstructural and structural alloy, Inconel600, was used microcompositional changes and on for the reactor. After irradiation, the their relationships to materials proper- stress rupture resulted from helium ties. In Arthur Rovvcliffe’s group, the produced by transmutation reactions main effortq are irradiating, character- involving boron- 10 in the alloy; simply izing, and testing developmental mate- put, the gas accumulated at the grain rials for fusion reactor applications, boundaries in the alloy and weakened and providing feedback to aid in devel- them. opin-g improved materials. In Randy

background Nanstad’s group the emphasis is on the Many Metals and Ceramics coworkers embrittlement and radiation-induced have contributed over the years, 8 elevation in the ductile-to-brittle transi- including Alan Brailsford, Bill Coghlan, tion temperature in ferritic steel pres- Roger Stoller, Man Yoo, Dora Pedraza, sure vessel alloys. In Tim Burchell’s Lou Mansur, and Mike Hayns. The group the emphasis is on radiation kinetic theory, which describes our effects in carbon and carbon composite best mechanistic and quantitative materials, including changes in me- understanding of radiation effects, chanical and thermophysical proper - draws heavily on diffusion, ties. In Lou Mansur’s group, the em- thermodynamics, kinetics, phase phasis is on understanding the mecha- transformations, and mechanics. nisms of radiation effects to develop Characteristically, the development of new and improved materials by means this theory has relied on close of combined theoretical and experiment cooperation with experimenters, and research. The aims are to predict be- has played both a guiding and havior during irradiation, develop supporting role in planning and principles for altering microstructure interpreting experiments. and composition to improve resistance to radiation effects, and explore the Using this theory, Division researchers unique research opportunities made concentrated first on understanding possible by the ability to displace at- and modeling radiation-induced oms. swelling, then on creep and embrittlement. These efforts have theory and shown how swelling is related to experiments competition between dislocations and cavities as sinks for point defects, kinetic theory of radiation effects described how cavities coalesce, helped understand how ion irradiations differ In the 197Os, the Division began work from one condition to another. Effects on the kinetic theory of radiation investigated included precipitates, effects, which is based on the dose-rate temperature shift, surface mechanisms and kinetics of defect effects, and diffusional spreading. reactions. This work guides the experimental program and builds on its One of the most important results. Researchers have developed an contributions of this theory has been extensive mathematical framework that the understanding of how gas atoms describes defect diffusion and contained in a cavity can be crucial in aggregation, the consequent evolution triggering the onset of unstoppable of microstructural features, and the growth of the cavities; i.e., the onset of macroscopic property changes that swelling. Helium generated by they in turn induce. background transmutation reactions or injected by embrittlement due to neutron exposure accelerator is crucial in this picture. was occurring in the reactor pressure vessel at a rate different than first 9 irradiation creep anticipated. Ken Farrell, Roger Stroller, and Tahir Mahmood, working with Over the past two decades, Division , Randy Nanstad’s group and Frank Kam researchers have also contributed to and coworkers, examined in detail the theoretical understanding of several physical mechanisms that irradiation creep. In some of this work, could be responsible for the apparent researchers have shown how early embrittlement. irradiation creep is driven by steady excess flow of point defects to These researchers examined effects of dislocations; this flow results in _ the soft neutron spectrum, the dislocations “climbing over” obstacles, extremely low damage rate, and the which leads to dislocation glide, each presence of an enormous event of which contributes irreversibly flux relative to fast neutron flux at the to irradiation creep. More recently, vessel. They found that the gamma ray Roger Stoller, Martin Grossbeck, Alan flux, which was a heretofore Brailsford, Bill Coghlan, and Lou unrecognized process of embrittlement, Mansur have carried out a series of may be contributing most to the early theoretical and experimental studies embrittlement. The soft spectrum effect focusing of creep contributions from and the low damage rate are still being transient (as contrasted with steady investigated. This work has stimulated state) processes. Occasionally, new research worldwide on the fluctuations in vacancy and interstitial mechanisms of pressure vessel concentration, which can occur for embrittlement caused by radiation several distinct physical reasons, can effects. In the Division, researchers lead to more creep than do the more continue to use not only neutrons to widely researched steady state investigate the problem, but are processes. irradiating materials with ions to better understand embrittlement. Ion radiation-induced embrittlement irradiation allows researchers to Division researchers currently are incrementally control microstructural examining the physical mechanisms of changes and, thus, to understand how radiation effects; specifically, radiation- each feature in the more complex induced embrittlement. This work microstructure arising from neutron began with the discovery that at the irradiation contribute to the- High Flux Isotope Reactor, embrittlement process.

background radiation effects research in the Solid launched important new work in the IO State Division ion beam modification of solids. Radiation effects research in the Solid broader applications State Division (part of the Metallurgy Division until 195 1) emphasized the As has been obvious from the earliest more basic aspects of defect research in Oak Ridge, the capability to production; both theoretical modeling irradiate materials is a powerful dimen- and fundamental experiment were sion of materials science that is much conduced. Mark Robinson, Dean Oen, broader than its most well-explored Tom Noggle, Ralph Coltman, and Jim subfield, materials for fission and Roberto (among others) were prominent fusion reactor applications. In 1990, in these efforts. Metals and Ceramics’ efforts expanded greatly in ion beam modification with Although Solid State is no longer some very important work on the ion involved in radiation effects to that beam modification of polymers. Eal Lee, level, it has continued to play a lead Monty Lewis, and Gopal Rao began role in the ion beam modification of work to improve surface mechanical materials. This field is closely tied to properties of polymer materials. radiation effects because many of the results of ion irradiation stem from the Normally, polymers are specified for highly defected structures and relatively mild materials applications. nonequilibrium states induced by Applications requiring performance in irradiation. Bill Appleton, Woody White, hostile environments, such as high Carl McHargue, Dave Poker, Jim hardness or wear resistance, are usu- Williams, and many others have made ally reserved for high-strength alloys or important contributions in developing ceramics. However, through use of this field. energetic heavy ion beams, researchers found that the hardness of polymers Consequently, dividing lines between can be increased one to two orders of radiation effects research and ion beam magnitude, rendering these materials processing are now dissolving. Solid substantially harder than stainless State ion beam researchers are steels. focusing more attention on displacement damage, microstructural Similarly, their wear resistance can be changes, and phase changes; and improved to the point where wear is Metals and Ceramics researchers who negligible in standard tests. In addi: were active in applying ion beams to tion, other improved properties - such understand fundamental issues in as extreme resistance to chemical radiation effects have recently solvents, resistance to oxidation, and

background many orders of magnitude increases, in periments are much less expensive and electrical conductivity - can be less difficult. achieved. ORNL has been one of the pioneering research capabilities laboratories in applying ion beams in radiation effects research. A triple- ORNL has extensive capabilities for beam facility consisting of 5-MV, 2.5- research in these areas. The High Flux MV, and 400-kV Van de Graaff accel- Isotope Reactor (HFIR) is used for high- erators has been developed. The high- dose, elevated-temperature irradiations est energy machine is usually used for both for basic research and for alloy heavy ions such as nickel or iron to development activities. produce radiation damage, and the smaller machines are used to simulta- For microstructural characterization, neously inject helium or hydrogen (or the Laboratory has a first-class center both) for studying the effects of impor- for state-of-the-art electron microscopy. tant transmutation products that The capability was built up initially would be produced during neutron under Jim Stiegler’s leadership in irradiations. In addition, the smaller response to the demands for accelerators have been used extensively microcharacterization of irradiated for ion beam processing research. materials. The facilities continue to Monty Lewis, assisted by Roy Buhl, Sy evolve and the extensive capabilities Cook, and Bill Allen, has largely been are now being applied to a wide range responsible for the full range of appli- of materials science research. The cation of ion-beam research in our Laboratory has extensive hot cell facili- experimental program. ties for postirradiation examination and testing of irradiated materials. conclusion

Unique capabilities for ion irradiations Because virtually all work on radiation have been developed. Energetic ions effects has taken place when modern from accelerators can produce atomic high resolution atomic and microstruc- displacements that are qualitatively tural characterization tools were avail- similar to those produced by neutrons able, the approach has been perhaps from reactors. However, ion irradiations more mechanistically oriented than offer many advantages for research. more traditional areas in metallurgy. Damage can be produced at rate lo3 to Theoretical research has been closely lo4 times higher than in reactors and, coupled with experiments designed to in addition, more flexibility exists in uncover mechanisms and to improve controlling variables. Accelerator ex- basic understanding.

background --- - __--- - metaIIoaraDhicU- I services

Not long after its formation, the Metal- Except to follow general investigative lurgy Division (now Metals and Ceram- steps, failure studies follow no recipe. 12 ics) recognized the need for a laboratory The many variables that influence a devoted to Metallography, the micro- failure require that one must study the scopic observation and study of metal- failure site in great detail while consid- lic structure. In April 1948, Bob Gray ering the design of the failed piece and joined the Division to form the Metal- the environmental influence. lography Group, despite misgivings from a change in the Division’s building Examples of reported failure analyses include fire-damaged pipe from the site during his interview and a change Strategic Petroleum Reserve, surgical in operating contractor a month after implants, aluminum tubing pitted in he started work. stagnant water, a 16-in. cast iron water As the Division grew, so did the metal- line, a transition weld joint, and a heat lography operation, eventually compris- exchanger from a coal processing pilot ing three groups: General Metallogra- plant. phy, Radiation Metallography, and Electron Metallography, with as many radiation as 37 people. metallography and vibratory polishing failure analysis Before the 195Os, it wasn’t unusual to Failure analyses have been major study radioactive materials set up challenges in metallography. Usually, behind a temporary shielding of lead the microstructures can reveal the bricks. This widespread approach was origin of a failure and offer proof of used at times in metallographic stud- changes that can often avoid future ies, both in preparation and examina- failures of that type. One of the first tion. The whole gamut of activities problems solved with the help of the dealing with highly radioactive materi- metallography laboratory was the als had to change as the need arose to failure of uranium fuel slugs in the study materials of higher activity. Graphite Reactor after an increase in the reactor’s operating level. The ura- nium fuel got hot enough to alloy with and penetrate the aluminum jacket, leading to oxidation of the fuel. Many other failures have been examined and reported through the years.

background designing and metallography personnel and ORNL constructing a engineers. This instrument had to 13 metallography confine particulates as well as alpha, beta, and gamma radiation. There was laboratory very little background information and Metallographers met with ORNL engi- experience to build on. neers who were experienced in the Dan Jones (Engineering Division) and design of facilities for working with Bob Gray (Metallurgy Division) made radioactive materials, giving input on numerous trips to Bausch & Lomb specimen cutting, embedding, grinding, Optical Co., Rochester, New York, and and polishing, etching, and the micros- W. J. Hacker Co. (Reichert Microscopes copy of materials. The need for a metal- of America), East Caldwell, New Jersey, lography facility in the High Radiation to assist in the early design stages for Level Examination Laboratory (HRLEL) each company. This assistance was became apparent, and the shielding essential so the companies could sup- cells for performing most of the metal- ply bids for the construction of two lographic operations could be fabri- shielded metallographs. cated at ORNL. (See Fig. 1.) The metallographs would be contigu- Doug Billington made the following ously affixed to the outside wall of a hot assignment to the metallography per- cell as separate “blister attachments.” sonnel: “Design and construct the nec- This location would protect the essary equipment and follow through metallographs, with their sensitive with the development of techniques and optics, from the background radiation conduct the necessary training of per- as well as the particulate matter that sonnel to perform a service that would most definitely would be present inside be equivalent to conventional nonradio- a working cell. Also, the metallographs active materials”; then he came out had to be accessible for service by a with that characteristic chuckle”and _ vendor’s engineer. said “I think that is impossible, but try to come as close to that goal as you The instruments would be attached to CEllIn the outside of a 3-ft-thick wall of high- density concrete, which would be the designing the barrier to the area where the metallo- metallograph graphic specimens would be prepared for microscopic study. After each speci- The design and construction of a light- men was prepared for microscopic illuminated metallograph for the exami- examination, it would be transferred nation of highly radioactive materials through an opening in the cell wall by was beyond the capabilities of the an automatic relay system and placed

background Fig. 1. The metallographic cells in the High Level Radiation Examination Laboratory are the four cells on the right. At the last cell on the extreme right is Larty Shrader. on the center of the stage of the metal- Grinding and polishing, however, had lograph for the microscopic examina- always been considered a “hands-on” tion. operation requiring an artistic touch 15 that was essential to be performed by designing a hand. This mindset had to be changed. microindention hardness tester Several methods were attempted to mechanically simulate the age-old Because no commercial company could hand-held methods of supporting the provide a shielded microindentation embedded specimen, but they always hardness tester, Ed Hutto (ORNL Engi- met with disaster. Keeping the neering Division) modified a conven- specimen surface flat and tional off-the-shelf Kentron Micro- perpendicular to the wall of the right Indentation Hardness Tester with cylinder plastic mount - a must shielding features and operational requirement for microscopy - was methods similar to those for the unsuccessful. Bausch & Lomb metallograph. It was positioned on a mezzanine directly Finally, a commercial vibrator was above the metallograph, and specimens adapted to polishing 24 specimens at were transferred to the hardness tester once. Shakedown tests with nonradio- in the same way as to the active specimens showed that this metallographs. method of specimen preparation would diminish the load on metallographers preparing radioactive and upgrade the quality and quantity metallographic of specimens to a considerable extent. specimens In fact, this introduced a new era of metallographic specimen polishing that The preparation of radioactive metallo- would have worldwide impact on the graphic specimens became a serious future of this discipline. hurdle. It would seem to be straightfor- Considerable credit must be given to ward: the metallographic specimen had Ernie Long, Bill Leslie, and Bob Crouse to be cut, embedded, ground, and pol- along with Maurice Allen, Bill Farmer, ished free of scratches and other arti- Neil Atchley, Ray Gaddis, and Larry facts that might prevent a valid inter- Shrader, who were great innovators in pretation of the microstructure. Cutting the development of vibratory polishing out the specimen and embedding it in a in the hot cells, in a glove box, and for plastic mount would be relatively general metallographic use. These straightforward and not,difkult“~ “I to , polishers can be operated 24 h a day perform remotely. unattended. The quality of the speci-

background men surface is far superior to that of which became the top of the support 16 specimens prepared by hand. table. glove box Encasing the metallograph in a plastic metallography glove box extended the spaces between the three components by several Glove box metallography became inches. Interconnection of these three needed for studies of alpha-emitting components required the design and materials such as . Metallog- construction of two sealed optical raphy laboratory equipment was de relays that passed through the glove signed and installed in a continuously box walls. The first relay transferred connected series of glove boxes. the light image to a forward position in the optical train. The second relay Nearly all the operations conducted in transferred the specimen image toward a normal metallographic laboratory - the camera with very little loss in light cutting, embedding in epoxy resin, image and no detectable degradation of grinding, polishing, etching, micro- the quality of the photomicrography. scopic study, photomicrography, photo- macrography, and micro-indentation did we meet doug’s hardness testing were carried out in challenge? glove boxes dedicated to these specific operations. Always, a negative pressure At this point it was reasonably safe to was maintained in case of a slight leak. state we had come very close to accom- Nearly all operations had to be carried plishing the “impossible challenge” out on a somewhat Lilliputian scale issued by Doug Billington. If he could because of the restricted working space have been here, he probably would in the glove boxes. have chuckled with pleasure at the quality and efficiency achieved in the An alpha-shielded metallograph was metallography of radioactive materials. required in the last enclosure of the glove box line. The optical alignment color metallography channel bar of an original Bausch & Lomb research metallograph was cut The application of color metallographic into three sections: xenon lamp, optical techniques for revealing microstruc- metallograph, and bellows camera. The tures began in this laboratory in the camera and lamp units remained mid-fifties. Some of the well-known outside the glove box, and the optical metallographers in the alignment - the channel bar - was and Canada had their start in the use replaced by a l/4-in -thick steel plate, of color by attending one of two teach- ing seminars held at ORNL in 1977 and 1978.

background Interference film metallography began very useful for the analysis of areas in the 1960s in Germany, and we with dimensions of the order of 1 pm. began using it fairly often. Jim Stiegler One of the very first instruments in the 17 and Bob Gray developed a method of United States for the analysis of radio- applying the interference layer to the active materials was installed in the surface of as-polished or lightly etched HRLEL. specimens. This procedure is particu- larly suited to specimens with dissimi- elevated-temperature lar materials, such as a braze joint. hardness testing electron metallography Elevated-temperature hardness testing and related techniques was developed by George Hallerman and Tommy Henson during the 1960s. Use of electron microscopy in the They modified a Rockwell Hardness Division’s metallography program was Tester for service from 25 to 9OOoC. pioneered by Ernie Long and Warren They also supervised the design and Bridges with a lOO-keV RCA instru- fabrication of an elevated-temperature ment. Its low energy and the technique micro-indentation hardness tes,ter that development of that time restricted its could be operated from 25 to 1000°C in use to carbon replicas for specimen a vacuum of 10m4 to 10e5 torr with a load surface examinations. Electron metal- range of 150 g to 3 kg. lography grew under the leadership of Jim Stiegler. Carus (Bud) DuBose These instruments were used for developed techniques to thin specimens screening metals and alloys to deter- sufficiently for transmission micros- mine plasticities at elevated tempera- copy without changing the internal tures. Hallerman also developed an structure. instrument for determining the crush- ing strength of SO- to 500~pm-diam Scanning Electron Microscopy (SEM) carbon-coated particles for became another useful procedure in gas-cooled reactors. the examination of radioactive and nonradioactive materials. One of the field metallography first shielded SEM units in the United Field (in situ) metallography became States was developed by Bob Crouse, very important for nondestructively built “in-house” for use in the HRLEL, determining the microstructures of and operated by Larry Shrader. plant components such as pipes, valve Electron Probe Microanalyzers, also, housings, weldments, and structural were installed in both the HRLEL and supports to predict life expectancy. The General Metallography and became area in question can be monitored to

background determine any changes in the micro- allows examinations up to 5000x in structure that would threaten its con- small areas, while the RTV rubber 18 tinued operation. technique permits examination of larger areas but at magnifications The area is prepared for examination limited to 500x. with portable tools, by steps closely related to those followed in conven- One of the early stages of crack forma- tional metallography. After the final tion that is searched for is grain polishing step, the area is etched and boundary cavitation. As the name then replicated with an acetate film implies, cavities can form at the grain previously softened by a suitable sol- boundaries, near inclusions, or at any vent. Also, a practice was developed by other discontinuity in the microstruc- Bob McDonald to replicate larger areas ture that could serve as a stress riser. from 2 x 2 in. up to 10 x 10 in. using A lineup of these cavities is a potential room-temperature-vulcanizing (RTV) start of a crack that should be consid- rubber. The acetate method and the ered for part replacement before a RTV rubber method have comple- catastrophic failure might develop. mented each other: the acetate method

background fundamental and applied research

Materials research in the current Met- fundamental research als and Ceramics (M&C) Division has generally meant studies supported by alloy behavior and design: experimental 19 the Office of Basic Energy Sciences Up to 1956 these studies were con- (BES) or its predecessor, Division of cerned with the development and Physical Research (DPR) in the Energy properties of thorium alloys. Research and Development Administra- tion (ERDA) and the Atomic Energy Zirconium alloy research was led by Commission (AEC). The goal of such Jesse Betterton during 1952 to 1966. research is the “fundamental” or “ba- This work sought alloying principles to sic” understanding of the behavior of guide the development of useful materi- materials and has been a part of the als with strong theoretical support from Division’s activities since its beginning. consultants. The choice of zirconium as the base material was influenced by the ERDA supported “applied” or “long- Laboratory’s focus on the homogeneous range applied” (4420 program) re- reactor and the emerging light-water search, along with “fundamental” (5000 reactor (LWR) technology. program) research until 1954. Then the _. .I .I.. Division of Reactor Development of AEC This group made major contributions supported “4420” or “applied research” to understanding the phase diagrams on materials of interest to several of Zr-Ga, Zr-Nb-X, Zr-Mo, Zr-Cu,’ Cu- reactor systems. These studies were Pd, Zr-Pb, and Zr-Cd. They pioneered transferred to the Liquid-Metal Fast the use of vapor pressure measure- Breeder Reactor (LMFBR), the Space ments to establish equilibrium condi- Reactor, or the DPR Vundamental” tions during annealing. George Kneip research programs during 1963 to determined the low-temperature spe- 1972. cific heats of Zr, Ti, Hf, Zr-Ir, and Zr-Sn for the study of density of states. Fermi The earliest budget document found in surfaces were mapped from Laboratory Records lists the following galvanomagnetic measurements at tasks in the “5000” program: Funda- 4.2 K for Zr and Be. Because of the mental Research, $22,000; interest in thorium metal, Larry Jetter, Tensile Properties of Pure Metals, Carl McHargue, and Harry Yakel used $11,000; Thorium Alloy Development, x-ray techniques to search for phase $22,000; and Preferred Orientations in transformations in Th and Ce metals in Uranium, $26,000.

background the temperature range 4.2 to 300 K. an understanding of annealing em- They found no transformation in tho- brittlement of amorphous alloys and 20 rium. suggested ways to solve this major obstacle to the commercialization of The alloy studies merged with the task such alloys. Metallurgy of Superconducting Materi- als, which had been started in 1961 at In 1984, these studies were combined the request of, and with the support of, with those on intermetallic alloys to the Sherwood Project (Fusion Energy). form the Alloy Behavior and Design These studies became a part of the (ABAD) task. This task, under the 5000 program in 1963. Under Gordon direction of first Carl Koch and then C. Love and later Carl Koch, extensive T. Liu, extended the studies on the role investigations of the effects of metallur- of boron in producing ductile, polycrys- gical structure and heat treatments on talline, intermetallic alloys such as superconducting properties began. N$Al. Cal White established the relative Alloy systems studied included Zr-Nb, rates of segregation of boron to free Zr-Nb-X, Mo-Re, Nb-Ir; V-Ga, Nb,Sn, surfaces and to grain boundaries. Man and other A-15 compounds. The group Yoo studied theoretically dislocation made significant contributions to the and point defect behavior and the role understanding of fluxoid pinning. A of twinning in the deformation of such Materials Science Award was received alloys. for its definitive studies on stress ef- fects on multifilament Nb-Ti and Nb,Sn alloy behavior and design: theoretical composites (Dewey Easton). Theoretical studies on electronic states In 1979, a transition to the study of were begun in about 1962 by Hugh metastable materials began. Studies on Joy, who considered the electronic the formation, structure, and proper- transitions in molten ionic materials as ties of amorphous metal alloys (metallic a part of the Spectroscopy of Ionic glasses) defined the quench rates ob- Media task. A separate task to develop tained in the arc-hammer and melt- solid-state theory for metals and alloys spinning techniques and pioneered the was formed in 1964 under the leader - use of mechanical alloying to prepare ship of Sam Faulkner. The group fo- amorphous alloys. An important con- cused on the Korringa-Kohn-Restocker clusion from the low-temperature (KKR) method for calculating electronic specific heat measurements of Don states, combining it with various tech- Kroeger is the existence of multiple niques such as Discrete Variational amorphous phases with boundaries Method, Coherent Potential Approxima- having characteristics similar to those tion, multiple scattering, and the muf- between crystalline phases. This led to fin-tin approximation.

background The early studies considered the elec- Research Gigaflop Award in 1990, and tronic structure and relations,hip to a NATO Collaborative Research Grant 21 various properties in Cu, Al, the third in 1991. transition metals, and diamond. The deformation, annealing, and mechyical problem of moving from ordered alloy behavior structures to disordered alloys was attacked as the obstacle to a full theory Initial studies were concerned with the of alloying. Success in these activities inherent brittleness of beryllium metal was noted by a Materials Science (until 1951); the tensile properties of Award for “Modern Theory of Metallic pure metals (i.e., is there a mechanical Alloys” given to Faulkner, Malcolm equation of state?) until 1952; and Stocks, and Bill Butler in 1982. Notable preferred orientation in reactor materi- achievements in calculation of electron- als. Studies on preferred orientations in phonon interactions were made by metals were active until about 1980. Butler and confirmed by measurements on niobium in the Physical Properties The interest grew out of the “Clinton task. Studies were extended to the slug problem,” the dimensional structure of clusters and surfaces by changes during thermal cycling or Gayle Painter. The interactions of neutron irradiation of extruded ura- various chemical species with surfaces nium rods used in the graphite reactor were modeled with increasing accuracy. at Oak Ridge and the production reactors at Hanford. Bernard Borie and By 1985, much of the activity turned to Larry Jetter developed the spherical x- the ordered intermetallic alloys in ray specimen, which eliminated the support of the experimental program need to correct for x-ray absorption and on the structure of high-tempera- during data gathering. Jetter, ture superconducting materials. The McHargue, and Robin Williams devel- surface studies were extended to in- oped the axis distribution chart or clude internal interfaces and questions “inverse pole figure” to describe tex- of segregation of impurities. tures. This work provided the founda- tion for modern texture representation. Malcolm Stocks won a DOE award for Outstanding Sustained Research in This effort established the importance 1989. Awards by DOE for Outstanding of initial orientation on final texture Scientific Accomplishment were (the mechanical stability of certain granted to Chong-Long Fu and Man crystallographic orientations - Yoo in 199 1 and to Bill Butler, Roy Vandermeer), the role of inhomoge- Xiaoguang Zhang, and Don Nicholson neous deformation or deformation band in 1995. Stocks et al. were granted the formation on texture (Richard Reed), Gordon Bell Prize in 1990, the CRAY and the effect of fabrication technique

background (extrusion, wire drawing, swaging, and These studies led to an improved un- rolling) on texture. Texture develop- derstanding of dislocation behavior in 22 ment in body-centered cubic (bee) hcp metals and the relative contribu- metals was studied with single crystals tions of slip and twinning to total defor- of Nb and Ta. mation. Roy Vandermeer extended the studies of annealing, which had fo- The potential of bee refractory metals cused on textures, to the mechanisms and alloys for space power applications of grain-boundary migration and the was of great interest in the 1960s. interaction of recovery and recrystalli- Deformation mechanisms were deter- zation as driving forces. The theory of mined for Nb, V, and Nb-V alloys. impurity-induced grain-boundary drag during recrystallization and grain Collaboration with the Electron Micros- growth resulted from studies of impu- copy task (Jim Stiegler) established rity-grain-boundary interactions. that dislocation velocity in niobium varied as the one-eighth power of stress In the late 197Os, the effort turned to and observed the effect of alloying on studies of impurity segregation to dislocation mobilities. These observa- internal surfaces (Cal White). The tions led to a proposal that the fric- observations provided input to the Alloy tional stress is composed of the Pierls- Behavior and Design task regarding Narbarro stress and contributions grain-boundary segregation and em- identified as size and modulus effects. brittlement and to the Radiation Effects task on the segregation of impurities to In 196 1, Deformation of Crystalline internal voids (produced by both creep Solids, under the direction of and irradiation). In 1984, these activi- Robin Williams, became a part of this ties were merged with the ABAD task. task. Williams and Alan Wolfenden studied stored energy in deformed fee ceramics research materials using a calorimetric tech- nique and internal friction. Richard Research on ceramic materials began Arsenault studied the low-temperature in the Division with the transfer of a creep of iron and determined the acti- 5000-funded task from Y- 12 Physics in vation energy and activation volume for 1951. This task, under J. Warde, con- dislocation movement in bee metals. tinued studies on these mat.erialsZuntil Man Yoo (1967) extended the conven- 1958, when the support was trans- tional elastic treatment of dislocations ferred to various projects. From 1957 to and dislocation-point defect interac- 1976, studies on high-temperature tions to include anisotropic elastic reactions of metals and ceramics and effects. spectroscopy of molten media under

background Pedro Smith were major activities in In 1963, the Basic Sintering Studies this task. The interest arose from (Chester Morgan) were transferred from 23 ORNL’s role in the Aircraft Nuclear the 4420 Program to the Fundamental Reactor Project (ANP) and the Molten Research Program. This task became Salt Reactor Experiment (MSRE). In Physical Ceramics in 1965, then Fun- 1976, the activities were transferred to damental Ceram+ (Bill Fulkerson) by the Chemistry Division. merging with a 4420 Program con- cerned with UN in 197 1, and finally During the period 1960 to 198 1, much Structural Ceramics including Erosion of the effort was devoted to the synthe- and Wear of Ceramics and Crystal sis of ceramic materials under the Physics in 198 1 (Vie Tennery and Paul direction of Wayne Clark (Crystal Phys- Becher). ics and Synthesis of High-Temperature Materials). The group had great success The sintering studies were concerned in growing high-purity, low-defect- with the role of plastic deformation in containing single crystals of ceramics the densification of ThO, and UO,. such as MgO, UO,, and various crystals Charlie Yust with L. Barrett (University doped with actinide elements. of Tennessee) and Fred Rhines (Univer- sity of Florida) used ideas taken from These crystals formed the basis for topology to describe the microstruc- numerous studies by other groups and tural changes that occur during densi- the Pure Materials Program of the Solid fication. Yust and McHargue studied State Division. A notable achievement, deformation mechanisms and disloca- which received an IR- 100 Award, was tion motion and substructure in ThO,, the growth of single crystals of metal UO,, and CaF, during high-temperature oxides with oriented metallic fibers by compression. Yust found that, contrary directionally solidifying metal oxide- to popular belief, dislocations were metal eutectics (Clark and Ted generated and moved during the im- Chapman). These early ceramic matrix pact erosion of A&O,. composites still hold promise for high- temperature applications. The war that followed the breakup of Belgian Congo caused great concern Among the techniques developed for about the cobalt supply to the United growth of ceramic crystals are hydro- States. Because of the importance of thermal growth; flame fusion; edge- high-precision machining to Y- 12 defined, film-fed growth; and internal- activities, this task began studies to zone growth. Many of)1 these techniques develop alternate tool materials. Work were successfully modeled in terms of with borides included experimental fluid and heat flow. studies on TiB,. F. Yen developed a

background process for liquid-phase sintering with In the period 1974 to 1980, studies on nickel, and a Materials Sciences Award the steam oxidation of Zircaloy were 24 was given to Vie Tennery, Cabel Finch, conducted to form the basis for deci- Charlie Yust, Wayne Clark, and Carl sions on the safe operation of LWRs McHargue in 1982 for u Processing and that.resulted from the Emergency Core Properties of TiB, Ceramics.” Cooling System (ECCs) hearing of the Nuclear Regulatory Commission (NRC). In 1985, Paul Becher began studies on transformation-toughened ceramics As the AEC began its transition to and whisker -toughened ceramics. ERDA in 1975, the studies of this These studies, along with those on group turned to the attack of metallic processing science, form the base for alloys by mixed gases (i.e., sulfidation), current activities. an area of interest to the Fossil Energy Program. Studies on the sulfidation of surface and solid-state reactions iron and iron-base alloys and the adhe- sion of resulting films continued until Studies on the oxidation of metals 1984. began in 1958 as a joint Metallurgy- Solid State investigation of the effect of Studies on Solid State Reactions began irradiation on the oxidation of Nb and under 4420 support in 1959 and be- Be. John Cathcart and Fred Young came Diffusion in Solids under 5000 concluded that there was no effect at support in 1965. It was merged with the flux attainable in the Graphite the Surface Reactions task in 1976. Reactor. The diffusion studies (Ted Lundy) considered self-diffusion and impurity In 1961, Cathcart began studies that diffusion in metals, alloys, and com- defined the effects of crystallographic pounds of interest to the Division’s orientation on the stress produced in programs. oxide films on copper and their role in oxidation rates. Richard Pawel ex- The studies on Cr (John Askill), Ti and tended these studies to refractory Ti-V alloys (James Murdock), beta-Z- metals and showed that the stresses (Ted Lundy), and Nb and Ta (Richard generated during oxidation could pro- Pawel) definitively showed that “anoma- duce plastic deformation of the metallic 10~s~ diffusion occurs in some bee substrate. In 197 1, they turned their metals. These studies stimulated an attention to uranium-base alloys, international conference on “Diffusion refractory-metal alloys, and stainless in Body-Centered Cubic Metals,” which steels. The focus was on determining was held in Gatlinbugg, Tennessee, in the rate-controlling step during oxida- 1964. The proceedings were published tion. by the American Society for Metals.

background The importance of grain-boundary and electron microscopy short-circuit diffusion in ionic solids was demonstrated for UO,, TiO,, TiO, Electron microscopy resided in the 25 and UN. Cation self-diffusion, Metallography Group until 196 1. The thermotransport, and concentration research efforts (directed by Stiegler, effects were defined for these materials. Ray Carpenter, and Jim Bentley) have The diffusion of and deuterium always had strong interactions with was measured for a series of oxides of other activities of the Division and the interest for nuclear applications. In scientific community. The initial stud- addition to the experimental studies, ies provided important information significant contributions were made to about the behavior of dislocations in the theory of mass transport in solids bee metals and alloys. The effects of under nonequilibrium conditions. temperature, solid-solution alloying, and interstitial impurities on the multi- In 1984, the task became Structure plication and movement of dislocations and Properties of Surfaces and Inter- formed a base for explaining the twin- faces. Carl McHargue and Bill Appleton ning, slip, and fracture behavior of Nb, (Solid State Division) continued under V, W, and their alloys. this support a study of the effects of ion implantation on the structure and Although studies of neutron radiation properties of ceramics begun under a damage in metals were conducted in “seed money” grant. the Division at its origin, the responsi- bility for such studies moved to the, With support from the Electron Micros- Solid State Division with its creation in copy task and collaboration with re- the early 1950s. Until about 1969, the searchers in France, Phil Sklad and Metallurgy Division was confined to the Pete Angelini showed that both dam- study of postirradiation effects, e.g., aged crystalline and amorphous sur- annealing microstiuctures, damage face layers can be produced by control from other energetic particles, and of the ion implantation parameters. mechanical properties. The electron Damaged crystalline surfaces are microscopy task permitted the Division harder than ,unimplanted surfaces, and to reenter the broader area of radiation amorphous surfaces are softer. The damage. studies continue with emphasis on the chemical effects of implantation and Initially ( 1965 to 1970), the radiation the mechanical properties of damage studies focused on electron nanostructures produced by ion-beam irradiation of aluminum and its alloys, treatments. voids produced in aluminum by quenching or irradiation, and the

background annealing of radiation-produced micro- line as this task developed the knowl- structures. Ben Loh initiated theoreti- edge base for their application. 26 cal studies on the interaction of vacan- cies, interstitials, insoluble gas atoms, In 1984, development and use of the and internal interfaces. Atom Probe (Mike Miller) were added to the task. Both advanced equipment By 1970, a large body of knowledge on and techniques are developed and the behavior of irradiation-produced state-of-the-art techniques are applied. defects in Al, Mg, Fe, graphite, B,C, The latter continues the tradition of and stainless steel had been amassed. collaborative research both insi,de and Such studies provided the base for outside ORNL. evaluation of High Flux Isotope Reactor research in x-ray diffraction (HFIR) components (Ken Farrell) as well as the development of the low-swelling X-ray diffraction techniques have family of stainless steels for the played an important role in the Division LMFBR. since its creation. Initially, the studies Once the Radiation Effects task began, were conducted under the supervision of M. Bredig (Chemistry Division). The the microscopy task turned its focus to 5000 Program began support of a task development of new techniques and led by Benard Borie in 1959. Borie and equipment for microanalysis. The Cullie Sparks advanced the analysis of activities emphasized Analytical Elec- diffuse scattering from alloys through tron Microcopy and in situ studies in their studies of ordered alloys; tem- the high-voltage electron microscope (HVEM). During the period 1976 to perature diffuse scattering; thermally 1982, eneru dispersive x-ray analysis excited, forbidden reflections; various and electron energy loss spectroscopy anomalous scattering events; and (EELS) were brought to a high state of resonance effects. development. Extension of EELS to Their measurements on thin copper include EXELFS in 1988 to 1989 allows oxide layers with Cathcart confirmed important information regarding the stress generation in films as thin as local surroundings of specific atoms to 10 nm and defined the stress gradient be defined. that exists between the metal-oxide In situ studies in the HVEM included interface and the free surface. oxidation of V and V-20°Ti, deforma- Harry Yakel determined the effects of tion of aluminum, and hydriding of neutron irradiation on the lattice spac- hydrogen-storage materials. Advanced ing and crystal structures of B,C, BeO, imaging techniques were brought on graphite, and other compounds of interest to the Division. Recognizing the

background importance of synchrotron-radiation- tion about the electronic structure of produced x rays, Yakel and Sparks solids. The physical property task conducted many x-ray scattering ex- (David McElroy) began as part of the 27 periments at the Stanford Synchrotron 4420 (AEC Reactor Division) Program Beam Line, including determination of in 1959, and transferred to the Funda- site occupancy in sigma and tau mental Program in 1963 and to the phases in the Fe-Cr and Fe-Cr-S sys- Conservation Program in 1984. A tems. Experience gained from these constant activity has been the develop- studies formed the basis for the ORNL ment of accurate measuring techniques beam line presently in operation at the and equipment. The result is a labora- National Synchrotron Light Source at tory with a wide range of facilities Brookhaven National Laboratory. Cullie whose operating features are well Sparks and Gene Ice developed new analyzed. and much improved optics for this facility. The studies can be characterized largely as electron conduction (in met- Small-angle x-ray scattering (SAXS) als) and phonon conduction (in insula- was pursued by Robert Hendricks in tors). The accurate measurements of the period 1973 to 1982. These studies the thermal conductivity in UO, and pioneered the use of position-sensitive the analysis of heat-conduction mecha- detectors and produced an ultrafast nisms contributed to the definition of data acquisition and processing system operating conditions for LWRs set by that is the heart of the ORNL 10-m the NRC and for the analyses used in SAKS system. Studies of voids in the ECCS hearings. Similar analyses quenched and irradiated metals and were made for potential nuclear fuel graphite, the mesostructure of coal compounds such as UN, ThN, and (voids and mineral distributions), and (U,Th)N. Total hemispherical emittance polymers resulted from its use. The measurements (Tom Kollie) of materials facility was later transferred to the such as Pt , Nb-1 %2x-, and INOR- management of the Solid State Division provide a design base for their use in as part of the National Small-Angle radiators and for safety analyses. Scattering Center. Electron conduction was studied in a physical properties research wide range of metals and metallic alloys, and the relationship between Accurate physical property data are electrical and thermal conduction was required for the safe design of most explored. The accurate measurements systems of interest to AEC, ERDA, or of phonon contributions to the conduc- the Department of Energy (DOE). Such tivity of niobium (Robin Williams) data also can give important informa- provided an important confirmation to

background the theoretical studies of Bill Butler stainless steels has been the focus of (Theory Group). With the increasing study. 28 emphasis upon energy conservation, the group turned its attention to the An important factor in understanding thermal-conduction mechanisms in weld microstructures has been grossly inhomogeneous materials the electron microscopy of John Vitek. (fibers, gels, etc.). The studies then Initial studies were concerned with became a part of the Conservation weld-pool solidification and the effect of Program. composition, residual elements, and cooling rates on the resultant micro- _. microstructure of coal structures. The stability of the weld- formed microstructures during As part of the program reorientation to long-time aging has been investigated support nonnuclear energy programs, in detail. As an understanding of weld the feasibility of using electron and pool solidification process was gained, optical microscopy to study the an increased emphasis was placed on structure of coals was explored during modeling heat transfer and its effect on 1975 to 1981. Larry Harris microstructures. demonstrated the usefulness of electron, conventional light, and These studies have led to a capability of infrared microscopy to define the predicting microstructures and phase amount and distribution of cavities and distributions for a variety of welding mineral microphases in a variety of processes. Laser welding and rapid coals. He found that these solidification have been investigated. microstructural features affected the Experimental studies of the microstruc- behavior during various coal- tures produced in single crystals of Fe- conversion processes. i 5Ni-15Cr of various initial crystallo- graphic orientations have confirmed research in welding and joining the solidification models proposed by this team. As a result of a national workshop organized and hosted by the Division in In 1982, the James F. Lincoln Gold 1977, research on “Engineering Medal of the American Welding Society Materials Science” was initiated by the was presented to Stan David for these DPR, ERDA. Among the first of these studies. A number of other awards new programs to be funded was have been granted to David, Vitek, and “Research in Welding and Joining” co-workers for results arising from this under the leadership of Stan David. task. The behavior of various austenitic applied research /

background “Applied” research was sponsored by (mostly, DPR, LMFBR, and Space) or the DPR of the AEC from the start-of phased out. the Metallurgy Division until about 29 1954. Tasks included in this program zirconium metallurgy were Creep of Uranium (1950 to 1954), Most of the 4420 activities are covered Physical Metallurgy of U-AI Alloys in other sections. Zirconium Metallurgy (1950 to 1952), Corrosion Studies (at Y- (M. L. PicMesimer) had its origins in 12 until 1952), and Ceramics Research the Homogeneous Reactor Experiment (1951 to 1958). In 1959, the Division of of ORNL and was continued until 1968 Reactor Development, AEC, initiated because of its importance to LWR long-range applied research (4420 technology. The main subtasks were budget category). The initial program in preferred orientation and anisotropic the Metallurgy Division was composed properties; hydride precipitation; oxida- of Physical Properties, Sintering Stud- tion; and alloy development in the Zr- ies, Reactions in Solids, and Zirconium 15Nb-X, Zr-Mo, Zr-Cu, and Zr-Pd Metallurgy. systems. Several patents were issued to Picklesimer and Phil Rittenhouse for With the exception of Zirconium Metal- fabrication schedules designed to use lurgy, these tasks were transferred to the preferred orientations and anisot- the Fundamental Program of the DPR, ropy of properties in design of reactor AEC, by 1965. Additional tasks in components. Materials Compatibility (1963 to 1970)) Fuel Element Development (1963 to Hydride precipitation was found to be 197 1)) Mechanical Property Research very sensitive to orientation and re- (1963 to 1966), Nondestructive Testing sidual stresses, and the precipitates (1963 to 197 l), High Temperature could be made to assume orientations Materials (1963 to 1966), Tungsten that would have the least effect on Metallurgy (1964 to 1965), Joining stresses encountered in service. David Research (1967 to 1973), and Uranium Hobson and Rittenhouse extended the Nitride ( 1964 to 1966) were supported studies from rolled sheets to tubing. by this program. Eventually, all tasks Studies on oxidation of &i.rcaIoy-2 and were transferred to other programs high-purity zirconium in oxygen and water (Picklesimer and John Banter) formed a base for the ECCS hearings and the NRC rulings on LWR safety.

background the roofs over our heads

Housing of the Metallurgy/Metals and several swimming-pool-type research Ceramics Division has taken many reactors and conducted workability 30 forms and locations over the last studies on tantalum, beryllium, and 50 years in keeping with changing other metals. missions of the Division. Some build- ings have been quite large and de- Before the rolling mill became signed to provide the special require- available, preliminary work on MTR ments for equipment or for contain- plates was done in an annex to the ment of radioactive materials. Other graphite reactor building locations were portions of existing (building 300 1). Scope of the work buildings adapted to fill Division needs included brazing of plates, a study of but, in some cases, closer to the pro- corrosion of aluminum alloys in high- verbial broom closet in size. temperature water, and primitive metallography. Following the end of World War II, a small amount of work on nuclear weap- metal casting and ons continued, but development of fabricating nuclear energy for conventional power generation and for research reactors Concurrent with the formation of the evolved rapidly. Little was known of the Metallurgy Division in 1946, Quonset- effects on materials of exposure in a style building 2000 (23,000 ft2) was nuclear reactor. Thus, new facilities designed; construction was completed such as those for the development of an in 1948. Its floor plan accommodated a aluminum-clad aluminum-uranium wide range of metal casting and fabri- fuel element for the Materials Test cation equipment; laboratories for Reactor (MTR), were needed. measurement of mechanical, physical, and chemical properties and metallo- the rolling mill graphic examination; and office space. The once-through ventilation and The rolling mill, building 30 12 exhaust system was designed to con- (1.1 ,000 ft2), was constructed in 1947 tain the toxic radioactive materials to

and was built for the express purpose l be handled and was equipped with of fabricating MTR-type fuel plates cyclone separators and absolute filters. (Fig. 2). This barnlike structure con- tained melting and casting, furnacing, The principal radioactivity to be con- and multipurpose rolling equipment. tained was alpha emission with a lesser The rolling mill and its personnel sub- degree of beta and gamma radiation. sequently provided fuel assemblies for Subsequently, building 2024

background : : 1 (10,300 ft2) was added between build- test loop buildings ings 2000 and 2001 to provide more 32 office and laboratory space. The high thermal density of ANP-type reactor designs required rapid heat the ceramists removal, a role uniquely filled by liquid metals or molten salts. Candidate Metals were not the materials of choice coolants included Li, Na, K, NaOH, and for all parts in some nuclear reactor fluoride salts. Of particular interest designs. Oxides of beryllium and ura- was NaK, a eutectic mixture of sodium nium were studied in early conceptual and potassium, which, along with the designs, as in the Aircraft Nuclear other alkali metals, is very pyrophoric. Propulsion (ANP) and Gas-Cooled Reactor (GCR) programs. Ceramists Compatibility with reactor materials joined the Division in about 1950 or was measured in thermally driven test 19 5 1 to work with these and other loops. Building 2005 (about 4000 ft2), nonmetallic materials. one of many frame structures built to serve the Manhattan Project, was Originally they were somewhat re- adapted in 1950 to house multiple test motely housed at Y-12 in building loops as well as the Division’s earliest 9766, a vintage frame building shared equipment for studies of welding, bras- with a machine shop. The cerarnists’ ing, and nondestructive inspection. equipment was located in two large bays, that contained powder condition- The experimenters performing the loop ing apparatus, presses, gas-fired fur- tests were frequently involuntarily naces, and a large electric furnace involved in spectacular pyrotechnic supplied with a hydrogen atmosphere. displays due to a loop failure or during posttest cleaning of the loop and test In 1951-52, building 9766 and subse- coupons. To minimize the chance of quently 9204- 1 (1954) also housed a injury during loop and coupon cleanup, metallographic laboratory that filled the building 3534 (450 ft’), a small brick needs of division personnel located at building, was built near White Oak Y- 12. They also provided the Reactor Creek and was better equipped to Chemistry Division with interpretive handle this potentially risky step. information for corrosion test capsules and thermal convection loops contain- mechanical properties ing molten fluoride salts for the Molten testing Salt Reactor experiment. Personnel in the laboratory moved to X- 10 in 1960. As the scope of mechanical properties measurements was increased, arrange-

background ments were made with the Chemical In 195 1 a portion of the Division’s staff Technology Division to use the base- left to form the Solid State Division for , ment of building 30 19 ( 1500 ft”) and study of the fundamentals of radiation 33 creep-test stands were installed. Even- damage and eventually to occupy tually, this work was relocated to build- building 3025 (59,000 ft2), which con- ing 2011 (2800 ft2), and nondestructive tained several hot cells. Effects ,of testing (NDT) equipment was moved radiatipn on the engineering properties from building 2005 to the 3019 base- of reactor materials were studied in the ment and subsequently, to the yet to be then Metallurgy Division. built wing of building 45005. The High Radiation Level Examination Building 20 11, which contained the Laboratory, building 3525 (27,000 ft”), original steam plant for the X- 10 site, was built for this work. Responsibility was the most unusual second-hand for the building was shared by the building acquired by the Division. Metallurgy and the Operations divi- Following construction of a new sions. The hot cells in building 3525 powerplant, building 2011 was vacated. were equipped for metallographic ex- After the boilers were removed, creep amination and measurement of the and fatigue machines were set up to mechanical properties of irradiated observe the effects of liquid metals and specimens. All operations in the cells liquid salts on metal samples. The were done remotely with master and effects, if any, of impurities in a helium slave manipulators. coolant on candidate High Temperature Gas Cooled Reactor structural materi- fusion reactor stud,@* als were also measured. This accommo- The Division provided support in 1958 dation was no doubt considered tempo- to the Fusion Energy Division to ad- rary, but lasted 40 years to 1993. The dress materials problems associated location, just south of the cafeteria, is with f&ion reactors. Metallurgy staff marked by a 180-ft concrete smoke members were initially located in build- stack. ing 9204-3 (assigned space was about new buildings 550 ftz), but later relocated to building 920 l-2 (about 2900 ft2). Recognition that exposure to the reac- tor environment causes changes in more new buildings both physical and mechanical proper- Division personnel had increased from ties of materials and a continuing about 45 in 1946 to over 200 in 1960. increase in the number of personnel in This and the penalty to performing the the division led to ti early restructur- Division’s work of having personnel so ing of the Division and the addition of widely separated were successfully two major new buildings. background used to persuade Congress to budget which provided a box working atmo- funds for a new home for the Division. sphere having very low oxygen and 34 The new home was provided in two water contents (in the parts per million adjacent buildings. One became the range). The inert atmosphere was westernmost wing of building 4500s. required for work with PuN and UN. Its approximately 65,000 ft2 is distrib- The boxes were equipped to synthesis, uted among fairly conventional labora- press, and sinter pellets of these ni- tory and office space on two floors plus trides. more open work space in the basement. fuel cycle alpha facility The second was building 4508, which contains approximately 99,000 ft2. As A companion laboratory, the Fuel Cycle designed, virtually the entire building Alpha Facility (FCAF) was assembled could be operated as a contamination for fabrication of PuO, and (Pu,U)O, zone. Architecturally, the building can fuel pellets and for coating sol gel be described as a box since it has no derived microspheres with pyrolytic windows, with a single exception. The carbon. Special target materials for the reasons for choice of a windowless High Flux Isotope Reactor were also design have been lost with the passage developed and fabricated. This labora- of time, but it provided a more assured tory was initially located in the base- secondary containment and reduced ment of building 3019 then was moved construction cost. and enlarged in building 4508. Two additional and unique fuel-rod-loading fabricating plutonium techniques, vibratory compaction and reactor fuels slug injection, were also studied in the FCAF. By the 1960s the need for information in the Fast Breeder Reactor Program on radon “scares” the fabrication and irradiation behavior of plutonium-bearing reactor fuels was An unusual natural phenomenon recognized. The Interim Plutonium occasionally causes complications for Laboratory (IPL) was assembled on the personnel working in contamination first floor of building 4508 within the zones. Workers in these laboratories confines of the Ceramics Laboratory. routinely check their hands and cloth- Placement of the IPL within building ing for the presence of radioactivity and 4508 was made possible by the shoe covers and clothing are scanned building’s secondary containment on exiting the laboratories. Air sam- design. pling is continuous. Monitoring is done to detect accidental release of activity The IPL was equipped with very high from a glove box. quality glove boxes and a purge system

background During weather inversions radon, throughout the building plus a multi- which is a naturally occurring release story high-bay area are particularly from the ground, is not dissipated as helpful in this regard. Building 4508 35 rapidly as in fair weather. The daughter provided space for relocation of the products of radon decay include addi- Ceramics Group from Y-12 in 1961. tional decay by alpha emission. This move improved communication with the ceramists and gave better Under some conditions, the radioactiv- recognition of the increasing impor- ity in the air drawn into a building for tance of their contribution to the air conditioning can be sufficient to Division’s work. Concurrently, the cause the monitors to alarm. Or the division was renamed the Metals and decay-product activity deposited by Ceramics Division. rain can be track into a laboratory. The laboratory personnel and their health A major addition to the Division’s physicist are faced with determining housing is building 45 15 (65,000 ft”), during inversions if there has been a the High Temperature Materials Labo- release from a glove box or if its just ratory (HTML) built in 1987. It is pri- one of mother nature’s pranks. marily a concrete structure featuring natural lighting for offices and corri- the division’s mission dors. The roof contains extensive sky evolves lighting. The laboratory space is fairly conventional, but the equipment in the The shift of the Division’s work away laboratories is state of the art. Work from nuclear reactor systems has conducted in the HTML is dedicated to nearly eliminated the need for the exploiting the high-temperature proper- containment feature of 4508. However, ties of ceramics to improve the perfor- the internal architecture of the building mance and efficiency of heat engines. makes it very compatible with the installation and operation of engineer- ing equipment. The 13-ft ceilings

background

1946-l 96.0 ornl graphite reactor

background trial engineers from,E. I. du Pont de Nemours and Company; construction 38 During World War II, a national effort of was performed by the du Pont organi- unprecedented magnitude was zation. The reactor was replete with mounted to ascertain whether fission- cooling system and control system as able 235U and 23gPu could be produced well as heavier shields, emergency in the quantity and purity required for shut-down capability, and means for use in atomic bombs. This mammoth manual charging and discharging of undertaking was conducted in utmost fuel. secrecy under the Manhattan District of the U.S. Army Corps of Engineers. The reactor had a design-rated thermal power of 1000 kW, a significant scale- The ORNL Graphite Reactor, formerly up from the 0.2-kW power level of the called the Clinton Pile and X- 10 Pile, Chicago Pile. Subsequent improve- played an important role in early veriti- ments in the fuel elements and installa- cation of a viable route for the produc- tion of higher capacity fans allowed the tion of plutonium. The major power output to be increased to objectives of the reactor and associated 4000 kW. separation plant, therefore, were essen- tially twofold: (1) to demonstrate that a The prototype reactor that evolved was reliable, self-sustaining chain reaction an air-cooled unit fueled with natural could be established with uranium metal, moderated with graph- natural uranium to yield sizable quan- ite blocks stacked to form a cube, 20 ft tities of plutonium by neutron trans- on a side. The fuel slugs rested on the mutation and (2) to demonstrate the bottom of diamond-oriented channels effective chemical separation of the of 1-3/4-in.-square cross section that resulting plutonium. The reactor was extended horizontally through the built in 1943 in less than ten months. graphite with sufficient excess space to permit air cooling. Each channel con- The ORNL Graphite Reactor, the tained up to 52 slugs, and a complete world’s second nuclear reactor, was reactor core loading consisted of about considerably larger than the first self- 42,000 slugs of unalloyed uranium. sustaining, chain-reacting pile erected and operated by and his The fuel elements were cylindrical slugs collaborators in Chicago in December of natural uranium metal, 1. l-in. 1942. It was conceptually designed by diameter by 4 in. length, canned in a cooperative effort between a research aluminum to protect from oxidation team at the Metallurgical Laboratory of and prevent escape or release of poi- the and indus- sonous fission products.

reacfor material years procuring reactor core sionally unstable when thermally materials cycled, and swells on neutron bom- bardment. Some of the difficulties 39 The procurement of highly purified associated with nuclear application reactor core materials was a critical arise from the occurrence of uranium.1 problem throughout the project. In in three allotropic forms; namely, the 1942, the lack of a commercial source alpha, beta, and gamma phases, each for uranium metal delayed somewhat with substantially different crystal construction of the CP- 1 at Chicago structure. and the Clinton Pile. The mining and concentrating of uranium ore, reduc- The low symmetry of the orthorhombic tion to metal, and the shaping into rod system leads to considerable anisotropy form on a compressed schedule were in alpha uranium, and heating and most challenging and difficult tasks cooling cause distortion. Fortunately, and were successfully accomplished by heat treatment in the beta temperature a host of dedicated people at various range refines the grain size and ran- firms. domizes the grain structure enough to provide acceptable dimensional stabil- The procurement of graphite was quite ity. different from that of metal because graphite was commercially available in Two types of fuel elements were manu- large quantities; hence, the graphite factured for the ORNL Graphite Reac- problem resolved to simply upgrading tor. The original unbonded slugs were purity and obtaining priority to pur- simply canned by inserting a beta-heat- chase, both of which were overcome. treated uranium slug into a deep- Following a suggestion made by the drawn aluminum can, placing a cap on National Bureau of Standards, a highly the open end, and forcing the assembly purified graphite with a neutron ab- through a sizing die to remove the sorption some 20% less than that of ambient air and to provide a good regular commercial grades was pro- thermal contact between the uranium duced in sufficient quantity to meet the and the aluminum. The closure at the demand. cap was welded to ensure leak tight- ness. developing the fuel elements An alternative process was developed to bond the uranium slug to the alumi- Severe limitations of unalloyed ura- num protective sheath to improve in- nium had to be overcome before it reactor performance. The new process could be used as nuclear fuel. It exhib- was similar to the old except that the its poor corrosion resistance, is dimen- uranium slug was dipped into a molten

reactor material years bath of aluminum-silicon alloy to form weld closure or diffusion of uranium a diffusion barrier at the interface. The through the can wall. 40 coated slug, can, and cap were then Tests made at various temperatures in assembled while submerged in a sec- ond aluminum-silicon alloy bath of the regime of interest revealed that at 250°C uranium will diffuse through eutectic composition to form a ther- a 30-mil-thick aluminum can wall in mally conducting bond and tight clo- approximately 4 days. Similar life tests sure. on bonded slugs showed that the alu- In addition, Jack Cunningham devised minum-silicon alloy diffusion barrier a similar technique to manufacture effectively retarded uranium migration. aluminum-clad, hollow uranium fuel In fact, bonded slugs heated for longer slugs for exposure of various experi- than 1000 h at 550°C showed no sign ments to fast neutrons and to permit of interdiffusion. As might be expected, the insertion of instrumentation for the bonded slugs performed very well reactor control. and were used for the remaining ser- vice life of the reactor. The performance of the unbonded and bonded slugs was monitored and ana- contributions of the lyzed by Charley Cagle, Bob Adams, graphite reactor and Ed Boyle. Generally, the in-reactor behavior of the unbonded slugs was Before being retired in November 1963, unsatisfactory. l&en though only 50 the reactor made a significant contribu- out of 160,000 slugs failed, the conse- tion to the advancement of nuclear quence was indeed serious. The slugs science and engineering. It was the very swelled, blocked the flow of air, and, in first reactor in the world to generate some instances, stuck in the coolant large quantities of thermal energy, in channel. the lOOO- to 4000-kW range, and thus confirmed the conversion of mass into The difficulty encountered in removing energy on a grand scale. Moreover, it ruptured slugs necessitated slugs more was the first nuclear reactor to demand resistant to failure. Several investiga- an elaborate system for removal of heat tions sought the nature and cause of and thus prevent meltdown of the failure. Thermal cycling experiments by reactor core materials. Bill Pellini, for instance, indicated that about 10% of the failures were due to It also provided an early incentive for improper heat treatment, while Larry the establishment of a uranium metal Jetter, Robin Williams, and others industry in the United States as well as traced the cause of the remaining for the production of nuclear-grade failures to either small leaks at the graphite. The cylindrical uranium slugs (sheathed in an aluminum container)

reactor material years developed for powering the reactor is In recognition of these major contribu- now known as the “classical fuel ele: ., tions, it was designated a Registered 41 ment.” National Historic Landmark in 1966 under the provisions of the Historic During its 20-year life, the reactor was Site Act of 1935 by the U.S. Depart- the first nuclear research tool to pro- ment of the Interior, National Park duce gram quantities of fissionable Service. It was also declared an ASM. 23gPu, urgently needed for determma- National Historic Landmark in 1969 by tion of the basic physical and chemical the American Society for Metals and properties of this heavy metal as well listed among the most renowned facili- as for other scientific investigations. ties in the world having made unique Finally, the reactor served as the pri- contributions to the advancement of mary source of supply of a wide variety materials science and technology. of radioisotopes used in the life and .,. physical sciences.

reactor material years materials testing reactor and other tank-type reactors

The main thrust on the atomic bomb cross section was surrounded laterally project began to abate in 1945, the by a solid beryllium reflector ring ap- 42 nuclear community at Clinton Labora- proximately 138 cm in its outside tories (now Oak Ridge National Labora- diameter. tory) turned its attention to harnessing fission energy for the betterment of The active lattice and reflector, as well mankind. The effort quickly revealed a as the shim-safety rods and drives, pressing need for a versatile experimen- were housed in a cylindrical aluminum tal reactor to provide intense sources of tank with a wall thickness of 2.5 cm. radiation for engineering tests to ex- All component parts within the tank pand our knowledge of reactor technol- were removable so that they could be ogy as well as to enhance fundamental ” replaced as necessary. They were knowledge. cooled with ordinary water, which moderated fast neutrons to thermal Several conceptual designs led to the energy and removed heat generated Materials Testing Reactor (MTR). This during reactor operation. “reactor designer’s” reactor was hetero- geneous (the fuel not mixed with the coolant), provided a high neutron flux, and was fueled by enriched uranium in a beryllium-reflected reactor, moder- ated and cooled by light water. The beryllium reflector ring laterally sur- rounded the core to minimize neutron leakage.

The professional members of the Engi- neering Materials Section of the Techni- cal Division (forerunner of the Metals and Ceramics Division) were respon- sible for these reactor components that have found widespread use in tank- type reactors throughout the industrial world.

Individual assemblies of MTR fuel elements (Fig. 3) were positioned as desired on a 5 X 9 grid array to form the active .core of the reactor. The fuel lattice of 40 by 70 cm in horizontal Fig. 3. Brazed MTR fuel element . without end fittings.

reactor material years fuel technology simultaneously framed and clad by roll bonding using the “picture frame” The MTR-type fuel element represented technique so as to hermetically seal the 43 a marked deviation from the classical fuel from the cooling water and retain natural uranium slug or rod in service the fission products. An exploded view at the time. It featured the use of highly of the component parts, which made up enriched uranium operating at both the composite plate before hot rolling, high specific fuel power and high spe- is shown in Fig. 4. The finished fuel cific power density to maximize neutron plate, therefore, consisted of a fuel- fluxes for irradiation testing. bearing or core section of uranium- aluminum alloy, which was clad on all The was incorporated in faces to form a composite plate with a the form of a uranium-aluminum alloy three-ply cross section. for several reasons: (1) to disperse the 235U fuel uniformly in a suitable diluent to maximize heat transfer surface area, (2) to maintain dimen- O~-LR-DWG~~~~ sional stability under severe neutron

bombardment by employing a radia- COVER SIEET tion-resistant alloy, and (3) to fur- ther enhance heat removal by use of a diluent and cladding material with good heat-transport properties and the needed chemical compatibility to promote metal-to-metal bonding. FUEL BEARING ALLOY OR POWDER PRESSED CORE Aluminum was chosen for cladding FRAME PIECE because of its low neutron absorp- r: tion cross section, availability, low cost, ease of fabrication, and ad- equate mechanical and chemical properties. Furthermore, aluminum COVER SHEET conducts heat well and possesses the necessary strength to withstand _ the thermal gradients and attendant stresses encountered in reactor service. Fig. 4. Exploded view shoing makeup of composite fuel plate before rolling. After casting and grain structure refinement by hot working, the resulting wrought alloy was

reactor material years Such composite plates were assembled MTR design presented the materials in parallel array, spaced to allow water engineers in the Metallurgy Division 44 to flow freely between them, and brazed with an urgent and challenging task. into a pair of side or spacer plates to There was, at the same time, essen- form an integral unit. At the suggestion tially no commercial demand for the of , then ORNL Research metal, except for small quantities of Director, the fuel plates were curved to beryllium-copper alloy; hence, the prevent bowing of adjacent plates in capacity of the existing beryllium in- the opposite direction and thus avoid dustry was severely limited. Beryl ore hot spots due to uneven cooling. was in rather short supply, and means to reduce this beryllium-bearing ore to The first core loading of MTR-type fuel metal of the desired purity and size for elements was manufactured and deliv- reflector application did not exist. The ered to the Low-Intensity Test Reactor situation was exacerbated further by (LITR) in the spring of 1950. The LITR, the anisotropic mechanical properties which in many aspects was a full-scale and brittleness associated with the mockup of the MTR, was constructed in hexagonal crystal structure the late 1940s to perform, initially, of beryllium. hydraulic and mechanical tests for verification of design parameters ‘and, Jack Cunningham investigated two subsequently, to conduct planned approaches to produce the desired critical experiments. beryllium metal: (1) melting and casting followed by extrusion to yield a wrought The fuel loading consisted of 2 1 stan- product and (2) preparation of powder dard elements (each containing 140 g and high-temperature sintering under 235U), 4 partial elements containing vacuum to a dense product. Both various amounts of.enriched fuel, and approaches were pursued with equal 3 shim-safety rods with in-line fuel vigor. sections for operational control. The metallurgical work was performed Attempts to upgrade purity of commer- under the leadership of C. D. Smith cially available, impure pebbles by with technical assistance from George melting under ‘vacuum were partially Adamson and Fred Drosten. The reac- successful, but the resulting castings tor achieved criticality in 1950 and was exhibited a rather coarse, columnar subsequently upgraded for higher grain structure. Extrusion of the best power operation. quality cast ingot yielded material that invariably contained internal cracks beryllium reflector and a coarse grain structure that gave rise to grain pullout during machining. The late selection of beryllium metal for reflector service in the evolution of the

reactor material years Brush Beryllium Corporation, working blocks was solved when Jack under subcontract, scaled up powder- Cunningham developed a modified rifle processing equipment and successfully drilling technique to produce 3/ 16-in.- 45 hot-pressed massive bodies, 14 X 14 X diam coolant charmels with the re- 60 in. The new powder product, desig- quired straightness. nated QMV, was dense and fine- grained. Furthermore, it was isotropic The significance of this development is compared with extruded stock and apparent when one considers that could be reproduced from lot to lot the requirement on length-to-diameter reliably. ratio for the MTR reflector coolant holes was considerably more stringent than At this point in the development of the that in the production of small-bore MTR beryllium reflector, the situation rifle arms. Furthermore, this was the had vastly improved. Yet, two problems first time that holes of this nature had remained to be solved: (1) the poor been drilled in a refractory metal like resistance of the powder product to beryllium. Needless to say, these metal- corrosion in ordinary water and (2) re- lurgical developments paved the way so moval of the sizable quantity of heat ! that the MTR reflector could be manu- generated in large beryllium pieces by factured from the new, nuclear-grade, neutron absorption and gamma ray QMV beryllium powder product. bombardment so as to avoid cracking in service because of excessive thermal The large beryllium pieces for the MTR stress. reflector were produced at Brush Beryl- lium Corporation and machined at the James English and Arnie Olsen found Y-12 plant. Over 100 vertical, horizon- that the hydrolysis of beryllium carbide tal, and diagonal experimental holes (which is present as an impurity) con- were provided in the beryllium reflector tributed significantly to corrosion of for irradiation testing of material sintered beryllium powder. The subse- samples and reactor components. quent tightening of specifications to minimize the presence of carbon (as mtr fuel production, well as neutron-absorbing elements research, and like boron and iron) ultimately resulted development in purer sintered powder with improved corrosion resistance. When the MTR began full-power opera- tion in May 1952, 23 fuel assemblies The switch from ordinary to demineral- and 4 fuel-shim rods, prepared under ized water for cooling the reactor gave the technical guidance of an added margin of safety. The problem Jack Cunningham and Richard Beaver, of heat removal from the large reflector were loaded in a 3 by 9 configuration.

reactor material years Each fuel assembly contained In May 1954, the fissile content of an 140 g 235U, and each fuel section of the individual assembly was revised to 46 shim rods contained 110 g 235U, giving obtain more efficient performance. a total of 3.66 kg 235U in the active core. These changes greatly reduced the number of new fuel assemblies re- This loading operated at 30-MW rated quired and correspondingly reduced thermal power until it automatically the number of new fuel assemblies that shut down because of reactivity losses had to be chemically processed to due to fuel depletion and buildup of recover the remaining 235U. fission-product poisons. In the fall of 1954, an increase in fis- Over the next two years, several modifi- sion product activity was detected in cations were made to gain excess reac- the cooling water, the source of which tivity to compensate for the rising load was traced to blemishes and a few of experiments inserted and to extend minor breaks in the cladding of the fuel life: (1) an increase in the 235U outside fuel-bearing plates. The fault content, (2) thinner fuel and side or was corrected by a small adjustment in spacer plates, (3) use of duplex-clad the dimensions of the end-box castings plate containing 12% silicon-aluminum to prevent minor buckling. Thereafter, braze alloy on one side to place the the MTR operated without difficulty. brazing alloy exactly where needed to minimize entrapment of brazing flux as The initial and subsequent loadings for well as to obtain sound joints, and powering the MTR, as well as the com- (4) switch from sand casting to perma- ponents for operational control, were nent mold casting to reduce final ma- manufactured at ORNL. chining cost. engineering test These alterations were made one at a reactor and related time with in-reactor testing of a full- tank reactors size element embodying each change to verify performance before use in a full The fuel and control components for core loading. the Engineering Test Reactor (ETR), located at the National Reactor Test Increasing the fissile content in the fuel Station (NRTS) in Idaho, are products assembly from 140 to 168 g, with a of materials research in the Metals and corresponding 20% fuel increase in the Ceramics Division. Like its MTR sister, shim rods, increased total energy the ETR is a light-water moderated and output from the core loading to 740 from 376 MWd.

reactor material years cooled reactor with a beryllium reflec- epilogue tor. It provides a large volume of in- reactor test space. There are many reasons why the MTR 47 project was perhaps the most signifi- Numerous fuel loadings for other tank- cant nuclear technological development type reactors have been manufactured of the past 50 years. First, the proto- at ORNL, including the fuel rods for the type reactor with many ingenious CP-3 reactor and the fuel plates and features was conceived, designed, the concentric fuel tubes for the CP-5; constructed, and placed in full opera- at Argonne National Laboratory, the tion in less than seven years. Second, plate-type fuel elements for the 5-MW more than any other test unit, the MTR Omega West Reactor at Los Alamos, contributed mightily to the establish- and the plate-type fuel assemblies for ment of the engineering base that the l-MW Brookhaven Medical Re- under-pined our heavy commitment in search Reactor. the nuclear industry to light water reactors for power generation. Third, it In addition, the Division manufactured served the Army and Navy exception- seven special loadings to investigate ally well in their utilization of nuclear stability in boiling water reactors science and engineering. And finally, it (BORAX 1 and 2) and various loadings contributed greatly to the advancement to study power transients in special of not only nuclear technology but also power excursion reactor tests (SPERT - 1 to the advancement of many branches and -2). Finally, special materials were of science, including the production of encapsulated for production of radioisotopes for research in the vari- transplutonium elements in the MTR ous fields of life science. for basic research.

reactor material years aircraft nuclear propulsion-aircraft reactor test

nuclear propulsion for ORNL felt that a liquid-fueled or liquid- aircraft moderated reactor with a negative tem- 48 perature coefficient of reactivity should Early in the development of nuclear be pursued. Extensive corrosion studies energy, the military recognized that showed that liquid moderators, i.e., nuclear propulsion could enable an NaOH or LiOH or hydrides, could not be aircraft to stay aloft for long missions used and that liquid fuels, uranium without refueling. Therefore the Man- dissolved in Pb or Bi, or slurry fuels also hattan Project contracted with the were ruled out because of corrosion and NEPA division of Fairchild Engine and mass transfer. Therefore, development Aircraft Corporation for a study work was concentrated on fused-salt “Nuclear Energy for the Propulsion of mixtures containing uranium. Aircraft (NEPA)” as a contractor of the Air Force. From 1952 to 1957, there was close cooperation between ORNL, ANP, and In 1949 the Atomic Energy Commis- P&W personnel. A large contingent of sion designated ORNL to represent it in P&W employees were on loan to ORNL a program involving other government and assigned to various activities from agencies and various industrial con- design, physics, shielding, engineering, cerns to develop nuclear aircraft, suc- chemistry, and metallurgy. ceeding NEPA. was selected to develop a direct cycle sys- This combined effort led to the Aircraft tem, and the Pratt and Whitney Air- Reactor Experiment (ARE), which was a craft Corporation (P&W) was selected to circulating fused-salt reactor, contained pursue an indirect cycle system, in in Inconel, moderated with BeO, and which a liquid metal carried the reactor cooled by sodium. The fuel and modera- heat to the propulsion machinery. tor coolant transferred the energy to helium and the helium dumped the ORNL’s major materials contributions energy to water (Fig. 5). were to the latter system. Examples of early work were determining suitable The ARE went critical on November 3, materials for the containment of heat 1954, at 3:45 p.m., and was carefully transfer agents, developing high-tem- shut down at 8:04 p.m. on Novem- perature fuel elements, and conducting ber 12, 1954, by Major General Donald neutron physics and shielding studies. J. Keirn, U.S. Air Force, Chief Aircraft Propulsion Officer, AEC, , aircraft reactor D.C. During the ARE’s run, reactor experiment kinetics were studied at various power levels, and the reactor was cycled 2 1 Because of the high power density that times from low power to full power of an ANP reactor would have to produce, 2.5 MW.

reactor material years 49

Fig. 5. Schematic diagram of the Aircraft Reactor Experiment.

aircraft reactor$est _ circulating fuel reactors was. suspended in September 1957. The ART was never The efforts of the combined P&W and built, but much of the hardware was ORNL team then centered on a more procured, including the largest single realistic reactor for an aircraft. These piece of beryllium fabricated up to that studies led to the Aircraft Reactor Test time, heat exchangers, and a spun- (ART). The ART was designed to be a fabricated Inconel container for,the _ ____ high-power-density, circulating fused- beryllium island. Much of the engineer- salt reactor with a beryllium modera- ing and materials knowledge gained tor and reflector, fabricated from was later used on the Molten Salt Inconel with an intermediate heat Reactor Experiment (MSRE). exchanger transferring energy to NaK and then disposing of the energy metallurgy’s role in the through high-performance radiators anp to air. From September 1957 until the ORNL- This reactor was to.be the culminUation ANP Program was terminated on of years of corrosion testing, both June 30, 196 1, research at ORNL static and dynamic, through capsule centered on shielding, materials, radia- tests, thermal convection loops, and tion damage, and experimental investi- pump loops, with and without neu- gations of systems and components for tron flux, and designing, building, and nuclear propulsion power plants. The testing all types of hardware including ANP at ORNL was the biggest man- pumps, valves, heat exchangers, power research and development effort duplex-metal heat exchangers and in ORNL’s history, employing more radiators, and radiators with high- than 5000 man-years of effort from conductivity fins for increased heat October 1949 to June 1961. transfer. The ANP-supported work on

reactor material years The Metallurgy Division (now Metals determined the effects of various envi- and Ceramics) had an extensive role in ronments; i.e., air, helium, vacuum the ANP under the direction of liquid metals, and fused salts; on the William D. Manly at ORNL, and the creep and rupture strength of materi- following laboratories were built and als; it also looked at complex stress staffed during this period: Welding and field effects on mechanical properties. Brazing, High-Temperature Reactions, Early work started on effects of irradia- Nondestructive Testing, Powder Metal- tion on creep and stress rupture prop- lurgy (later called Fabrication), General erties of alloys, and also design stress Corrosion, Dynamic Corrosion, and loads were developed for the reactor Mechanical Properties. In addition to designers. the laboratories, metallurgists were assigned to the design, experimental The Fabrication Group (Sloan Bomar engineering, and procurement func- and John Coobs) found the proper tions of the program. combination of materials for control rods, pump seals, and valve seats. It The Welding and Brazing Group developed the high-conductivity radia- (Peter Patriarca and Gerald Slaughter) tor fins and coordinated all the activi- developed novel tube-and-header weld- ties that led to new alloys. ing techniques for heat exchangers. It also developed brazing alloys and early metallurgical placement methods to back-braze tube- work to-header joints and braze high-con- ductivity fins to tubes for radiators. The first metallurgical work on the ANP Proper techniques for heavy-section Program at ORNL was basic compatibil- welding of nickel-base alloys and stain- ity studies of construction materials less steels were another achievement. with various high-performance heat transfer agents such as Li, Na, NaK, The Nondestructive Testing Group and Pb followed by NaOH. The Division (Robert Oliver and Robert McClung) developed purification and handling developed ultrasonic, eddy current, x- techniques for the coolants. The early ray, and dye penetrant inspection ANP materials program was directed by methods for materials as varied as 4- Ed Miller. He was followed in 195 1 by in.-thick nickel-base alloy plates to Bill Manly. Early key investigators in thin-walled (0 .O 15-in.), small-diameter the corrosion area were George tubing for heat exchangers and radia- Adamson, Antoin Brasunas, Gene tors. Hoffman, and Pedro Smith.

The Mechanical Properties Laboratory As the program progressed, the corro- (Robert Oliver and Donald Douglas) sion testing evolved from static cap- reactor material years sules, through thermal convection weldability. INOR- development was a loops, to full-scale pump loops with team effort of corrosion, fabrication, heat exchangers and radiators. As a welding, and alloy development person- result of this work, the compatibility of nel at ORNL with assistance from materials for these heat transfer agents ’ metallurgists and alloy developers from was catalogued, and interesting phe- the International Nickel Company. nomena, such as isothermal dissimilar- metal transfer and temperature-gradi- metallurgical ent mass transfer, were experienced engineering and studied. In looking back at the ANP from a corrosion studies metallurgical engineering standpoint, it was a very exciting time with very The corrosion studies (Gene Hoffman interesting challenges in the field of and Jack DeVan) with fused fluoride corrosion - liquid metal, fused salt, salts led to understanding the basic and oxidation; alloy development; mechanism of corrosion, which was the powder metallurgy; unique fabrication selective leaching of chromium from including welding and brazing; and the solid-solution Inconel alloy. The nondestructive testing. All these spe- Inconel specimens showed subsurface cialties provided information that led to voids not connected to the surface, the design, procurement, and final which were formed by the collection of inspection of many uniquely designed, vacancies. This led to the careful re- complex pieces of reactor hardware. moval of impurities from the fused-salt The personnel of the Metallurgy Divi- bath to study the reaction. sion were up to the challenge.

development of inor- flow of knowledge

As a result of these studies, an alloy One of the more interesting aspects of development program, under the ANP was the extent of interplay that Henry Inouye, was undertaken that led developed among the designers; heat to INOR- (composition Ni, bal.; MO, transfer, fluid flow, and structural 17; Cr, 5; C, 0.06), which had chro- engineers; and the various materials mium sufficient to form an adherent specialists. An example of this interac- spine1 oxide film but low enough to tion was the design, construction, and minimize chromium removal in the testing of thin-walled, small-diameter fused salts, and sufficient molybdenum heat exchangers - the tubes failed at to provide good strength. the tube-to-header joint. Careful study determined that the drag coefficient of The residual elements Mn, Si, and Al the liquid on the tube, coupled with were controlled for fabricability and

reactor material years temperature fluctuations, developed a ciated and used by project personnel. cyclic load on the joint. Back-brazing As a result of working with the many 52 this joint produced a much stronger, disciplines on the ANP, metallurgists load-bearing joint that solved the prob- were accepted as full team players. lem. Another example was to develop an efficient liquid-metal-to-air radiator The corrosion studies, alloy develop- incorporating a high-thermal-conduc- ment for containing fused salts, as well tivity fin. This was accomplished by as component development of pumps, cladding OFHC copper with stainless valves, and heat exchangers, were used steel with a diffusion barrier between in the Molten Salt Reactor Program for the copper and stainless steel. This fin the MSRE, which is the subject of was then brazed to the Inconel tubes. another article in this document. The extensive compatibility studies in the impacts of anp ANP and MSR programs from 1952 to program 1972 on a large number of refractory alloy-liquid metal combinations were With the startup of various laborato- the basis of the SNAP-50 Program, ries, each functional laboratory had at which used lithium as the heat transfer least two missions: One was to apply agent contained in Nb-1% Zr alloy, its expertise to the various problems and they are presently being utilized in faced by Laboratory projects, and the the development of advanced nuclear- second was to conceive and conduct powered systems for future U.S. space applied research within its specialty. missions. This mixture led to the growth and excellence of the technical staff. The subassembly, design, construction, and test procedures for complicated As a result of all the interplay with hardware developed on the ANP Project designers and experimental engineering were used in later reactor projects. groups, the materials effort was appre-

reactor material years homogeneous reactor project

Participation in the Homogeneous (HRT), to demonstrate engineering Reactor Project (HRP) by the Metals feasibility and operating perfor- and Ceramics (M&C) Division started mance 53 as a small effort under Ed Miller. He . An intermediate size, power breeder directed the materials program from prototype. 1951 to 1955 and was followed by The program in M&C was a project- George Adamson from 1955 to 1960. type organization incorporating, at The purpose was to furnish materials various times, engineers experienced in support to the reactor designers and metal fabrication, welding, inspection, engineers in developing and fabricating physical metallurgy, alloy development, homogeneous reactor systems. (A and mechanical properties. It varied in homogeneous reactor is one in which size from three to ten technical person- the fuel is in the coolant.) nel functioning originally in a single The HRP was a major ORNL program group and ultimately in two groups, originally directed by John Swartout, research under Marion Pickelsimer and who was followed by Beecher Briggs in engineering assistance under Sloan 1956. The HRP was aimed at develop- Bomar. ing a power reactor fueled by a circulat- The HRE operated successfully for two ing aqueous solution of uranyl sulphate years in the early 1950s as a two- (UO,SO,). With the addition of a tho- region reactor with a light water solu- rium oxide slurry as a blanket, it pos- tion of UO,SO, as the fuel and heavy sessed the potential of becoming a water as the blanket. It consisted of an breeder reactor. 18-in-diam, type 347 stainless steel, As might be expected in such systems, spherical core vessel surrounded by an corrosion and fuel solution stability A- 105 steel pressure vessel. were the major problems. The primary The design pressure was 1000 psi, with responsibility for each was assigned to an operating temperature of 250X!, and established groups in the Reactor it operated for 1950 h while critical and Experimental Engineering Division 720 h at powers of 100 kW or more. located at the Y-12 facility. The cost of constructing the reactor The HRP was divided into three phases: system was only slightly more than $1 million plus fuel and . . A small, low-power reactor, Homog- Metallurgical efforts were limited to enous Reactor Experiment (HRE), providing advice to the designers and to demonstrate overall feasibility fabricators. and solution stability. . A moderate size, two-region reactor, The second phase of the program, the Homogeneous Reactor Test involving the building and operation of

reactor material years the HRT, was the heart of this program. plates and forming and welding them to The HRT was a 5000-kW, two-region form the Zircaloy vessel. 54 reactor with a l/4-in.-thick, 32-in.- diam Zircaloy-2 (a Zirconium alloy) core At the time this work was done, the vessel and an SA-2 12 pressure vessel, technology of zirconium was limited to 5 ft in diameter, internally clad with fabrication, largely in dry boxes, of stainless steel. A solution of UO,SO, in plate and tubular fuel elements. Tech- heavy water circulated through the niques were needed for both straight core, and heavy and cross rolling in water circulated in air to obtain plates the blanket or large enough to reflector region. Its form the core tank. design operating The tank was conditions were assembled by 300°C a pressure welding 15 pre- of 2000 psi, and a formed plates and power density of 17 tubes and then kW/L. light machining to finished size. Glen Elder and Ed Miller of the M&C Even with this Division played a active metal, weld- major role in devel- ing techniques were oping and imple- developed for mak- menting fabrication ing all welds in air techniques for both by a consumable vessels. The com- insert root pass mercial fabricator with helium-filled was Newport News trailering shields on Shipbuilding and the torch to protect the Zircaloy from Drydock Company Fig. 6. Bulb-shaped core vessel built of Newport News, for the Homogeneous Reactor Test. oxidation. A spe- Virginia (Fig. 6). cific trailer was made for each joint configuration. Unusual fabrication practice for the Achieving the necessary welding repro- pressure vessel involved forming the ducibility and tolerances required hemispherical heads and welding the developing and qualifying special girth closure, of necessity from the Heliarc welding procedures with con- outside. For the core tank, the unique sumable root inserts for use in assem- accomplishment was fabricating large bling the reactor stainless steel piping

reactor material years system. This was accomplished by a opening under a pool of water. Peri- joint effort of the M&C Division and the scopes built by the P&E and Instru- Plant and Equipment (P&E) Division. ment and Controls Divisions were used 55 to examine the inside of the vessel, As the HRT approached startup, the revealing the hole and the loose M&C program grew and changed to screens. developing new materials aimed at the more demanding large reactors. These Clarence Wodtke and Plant and Equip- material studies were primarily of the ment personnel developed a miniature fabrication and properties of titanium Heliarc cutting torch that entered the and zirconium alloys. A major program core and cut all the diffuser screens under Marion Picklesimer worked on into strips of a size that could be re- the morphology, transformation kinet- moved and also cut samples from ics, mechanical properties, and fabrica- around the tank failure. tion of new zirconium alloys. The result was a family of zirconium alloys with 15 Using his knowledge of the morphology to 30% Nb and minor other additions. of zirconium alloys, Pickelsimer exam- These alloys showed both improved ined samples in a hot cell and estab- mechanical properties and corrosion lished that failure of both the screens resistance over Zircaloy-2. and vessel was the result of melting. He also established, by determining tem- The HRT was operated at low powers perature profiles, that the incidents of for about 500 h early in 1958; the melting were of short duration. The hot power was then raised in lOOO-kW spots had been caused by high heat steps to the design level of 5000 kW. generation. in uranyl sulfate, which had Shortly after design power was reached, separated from the fuel solution onto a 2-in. hole developed in the lower metal surfaces in regions of flow per- diffuser portion of the core tank. Also turbations. some of the diffuser screens had come loose from the vessel. After the cause of the core vessel failure was determined and the damaged The M&C Division played a major role screens were removed, a cover plate in examining and analyzing the condi- was bolted over the hole to retard tion of the core vessel. The high radia- mixing of the core and blanket solu- tion levels restricted access to a 2-in. tions. Operation was resumed with some uranium in the blanket. It contin- ued until the HRP was terminated in 1960.

reactor material years

1950. 9 7 5 the army package power ‘reactor program

In 1954, ORNL was assigned responsi- spaced 0.133 in. apart and metallurgi- bility to assist the Atomic Energy Com- cally joined to thin austenitic stainless 58 mission (AEC) in the Army Package steel side plates. Power Reactor (APPR) Program. The U.S. Army was interested in supplying The refractory compound UO, was nuclear electrical power to remote selected because it is chemically inert locations. A major requirement was to in contact with austenitic stainless keep the power unit small and the steel, exhibits good resistance to 232°C parts sufficiently compact to be readily pressurized water, is relatively insensi- packaged and transported to the re- tive to radiation damage, and retains mote locations (thus, the program title). fission gas well.

This required the use of uranium Boron was selected as the burnable highly enriched in the 235U isotope to poison because its nuclear burnout achieve a high power density. A de- characteristics closely match those of tailed conceptual design by ORNL, for the fuel; B,C was selected because of the first time, considered a dispersion its availability and prior experience of highly enriched UO, and a burnable with it dispersed in stainless steel. poison in stainless steel for a power However, tests of such dispersions reactor. The architect-engineer (ALCO revealed incompatibility when heat Products, Schenectady, New York), treated above 1150°C. Other com- designed the reactor generally following pounds, including boron nitride and the ORNL conceptual design. zirconium diboride, were found unac- ceptable. Restricting fuel element The AEC assigned ORNL as a consult- manufacturing temperatures to below ant to help establish the final design, 1150°C solved the problem. as well as to develop and manufacture the 45 fuel elements and 7 neutron By July 30, 1956, except for the Eu,O, absorbers required for the lo-MW neutron absorbers, manufacture of the training reactor (APPR- 1) at Fort first core loading was completed (38 Belvoir, Virginia. stationary fuel elements, 7 fuel elements, and 7 Be-Fe neutron Al Both was the ORNL Director of the absorbers). Along with the additional APPR Program, Jack Cunningham was Eu,O, neutron absorbers, they were the M&C Division Program Manager, shipped in December 1956, five months and Richard Beaver was the Project ahead of the original intended sched- Leader of fuel element and neutron ule. More than 1200 fuel plates were absorber development and manufactur- manufactured with negligible rejec- ing. The fuel element consisted of tions. No fuel elements or neutron 18 thin austenitic stainless steel plates absorbers were rejected. APPR- 1

reacfor project years achieved full-power operation in April of UO, in stainless steel) and neutron 1957. As a conclusion to the program, absorbers (using a dispersion of Eu,O, detailed specifications were prepared to in stainless steel) can be produced on a enable procurement of the UO,-stain- commercial scale and made useful for less steel fuel elements and the Eu,O, small, compact reactors that need to neutron absorbers. These were used to ,, achieve a high power density. procure the core loading for the pack- The M&C Division received a personal age reactor at Fort Greqley, Alaska. commendation from Alvin Weinberg, The ORNL program and the M&C Divi- Director of ORNL, for its achievements sion project established that the plate- on the APPR Program. type fuel elements (using a dispersion

reactor project years 0 nference aY reactor introduction August 8. President Eisenhower was among the tens of thousands of visitors 60 The U.S. research reactor exhibited in who observed the characteristic blue operation at the first International glow, known as the Cerenkov effect, Conference on Peaceful Uses of Atomic caused by the slowing down of high- Energy won undisputed honors as the energy radiation in water with the Best Display at the conference, which release of some energy as visible light. was held from August 8 to 20, 1955. As Upon seeing this dramatic demonstra- a consequence, this greatly enhanced tion of conversion of mass into energy, the prestige of the Nation and the Mrs. Enrico Fermi called the Laboratory in nuclear science and U.S. display “the prettiest reactor ever engineering. built.”

In early 1955, when the Atomic Energy project completed Commission (AEC) requested ideas for display of recent advances in nuclear Despite the problems encountered in science and technology at Geneva, the the manufacture of partially enriched Laboratory was preoccupied with the 235U fuel components, the project was preparation of a host of technical pa- completed on schedule and thus per- pers for presentation. In response, mitted successful demonstration of an however, many display ideas came forth operating research reactor at the first from Laboratory personnel, including Geneva Conference. the suggestion by Tom Cole that the Laboratory display a full-scale operat- far-reaching benefits ing research reactor. The Division and ORNL saw many In a short span of about four months, a benefits that accrued to mankind, in research reactor of the “swimming pool” general, as well as to the variety was designed, constructed, and U.S. Government. tested by ORNL personnel. Meanwhile, l The display of a partially enriched work had been started on a special 235U pool reactor with associated building in Geneva, Switzerland, to technical panels served as an excel- house the reactor and associated dis- lent vehicle for technology transfer play panels, and by June 7, 1955, it in such diverse fields as education was completed. in nuclear science, reactor design, The disassembled reactor was pack- research in nuclear engineering, aged and shipped by air freight to study of radiation effects, produc- Geneva, where it was reassembled and tion of radioisotopes, activation tested before the official opening on analysis, neutron therapy, biomedi-

reactor project years cal research, radiation detection, reactors by contributing one-half and protection of personnel. the cost and furnishing the partially enriched uranium fuel required. 61 l The display focused on promoting peaceful uses of atomic energy in . Compliance with the nonprolifera- keeping with the spirit of the confer- tion policy of the government to ence as well as in accord with the limit enriched uranium for..“.a. export to U.S. offer to assist other free na- a non-weapons grade containing tions in obtaining similar research less than 20% enrichment in 235U.

reactor project years thorium metallurgy

During the period of optimism regard- thorium alloy fuel and thorium metal ing the development and application of as the fertile material. 62 nuclear reactors, there was much interest in the potential of thermal Because of this potential of using reactors using 233U as the fuel. Many of thorium in the fuel or as the fertile the concepts were based on breeding or component, the Atomic Energy Com- conversion using 232Th as the fertile mission sponsored a large program to material. develop the metallurgy of thorium in the period 1949 to 1956. By 1956, the Two reactor experiments initially using basic physical metallurgy of thorium solid 235U fuel and thorium as the fertile and a limited number of its alloys had material for conversion to 233U and two been established at ORNL. experiments using fluid fuels were planned in the late 1950s. The CETR During this period, the Division of (Consolidated Edison Pressurized Water Physical Research of the Atomic Energy - Thorium Convertor Power Reactor) Commission supported research in the was designed by Consolidated Edison Metallurgy Division of ORNL at a level of New York and scheduled to become of one to five persons per year. The operational by 1960. This reactor work included studies on preferred would have used a uranium-zirconium orientation and anisotropy of mechani- alloy fuel and thorium metal clad in cal properties, mechanical properties of zirconium as the fertile material. The thorium alloys at room and elevated SGR (Sodium-Cooled, Graphite-Moder- temperatures, recrystallization studies, ated Power Reactor) was designed by fabrication and cladding studies, and Atomics International to use uranium- limited alloy development.

reactor project years fusion materials program

In the fusion reaction, nuclei of light serves to remove helium “ash” from the, _ elements, such as isotopes of hydrogen, plasma. combine to form heavier elements. and, 63 in the process, release large amounts of About 20% of the energy of the fusion energy in the form of energetic particles reaction, the energy carried in the whose kinetic enerw can be converted alpha particle, must be removed as a to heat. The fusion reaction that is _ ,, heat flux through the surface of the easiest to attain is that of the two first wall and divertor. The blanket hydrogen isotopes, deuterium and structure has two primary functions: tritium. This reaction produces recovery of the 14.1-MeV energy con- 17.6 MeV carried by a 3.5-MeV alpha tamed in the neutron and containment particle and a 14. I-MeV neutron. of the tritium breeder for producing tritium. For this reaction to occur at sufficiently high rates to produce useful energy, a The blanket and shield together serve mixture of deuterium and tritium gas to reduce neutron and gamma radia- must be heated to temperatures in tion levels at the toroidal field (TF) excess of 150 X 1 060C. At this tempera- magnets and beyond. The TF magnets ture the deuterium and tritium atoms produce the magnetic fields which are ionized, forming a plasma consist- contain the plasma. For reasons of ing of the atomic nuclei and electrons. efficiency, the TF coil will be supercon- ducting. Beyond the fusion core is a The plasma is confined by magnetic system for converting the heat of the fields within a vacuum chamber. Deu- fusion reaction into electricity or for terium is readily available in nature. use as .process heat. Tritium, however, is an unstable iso- tope of hydrogen, having a half-life of beginnings of the only 12 years, and is thus not naturally fusion program occurring. In a fusion reactor tritium will be produced by capturing the The U.S. Fusion Program had its begin- fusion neutrons in lithium. ning in the early 1950s. According to recollections of Bill Manly, the Oak The International Thermonuclear Ridge National Laboratory Metals and Experimental Reactor (ITER) is planned Ceramics (M&C) Division and its prede- for operation shortly after the turn of cessor, the Metallurgy Division, first the century. The basic components of a became involved in fusion in 1956 magnetically confined fusion reactor when a meeting was held at the Atomic core, progressing outward from the Energy Commission in Washington, plasma are the first wall of the vacuum D.C., to consider the development of chamber and the divertor. The divertor reactors. Demonstrating

reactor project years that the fusion reaction could be Today, however, in terms of plasma achieved and controlled in a plasma of parameters and experiment size, we are 64 deuterium and tritium was expected to close to the goal of building a fusion be accomplished in the very near term, reactor, although the time scale re- i.e., a few years. mains decades. Ironically, as we ap- proach the conditions that will exist in The next logical step was to build a a reactor, there is an increasing realiza- reactor that would harness the fusion tion that the materials problems are reaction to produce electricity. Attend- also much more formidable than previ- ees at this meeting from ORNL included ously thought. program managers Ed Shipley, Arthur Ruark, and Bill Manly of the Metallurgy the sherivood project Division. The meeting proved to be a harbinger of the future fusion program; In 1958, Manly introduced Bob most of the meeting was devoted to Clausing to the fusion program. The discussions of plasma physics, and program was classified Secret and had only at the very end, when little time the code name Sherwood Project. When remained, did the group turn to Manly Manly mtroduced Bob Clausing to Ed and ask what materials could be used Shipley, Director of the Sherwood for construction of the blanket. Project, he told him he had brought one of the Divisions’ youngest scientists to At that time, the thought was to use fusion because he figured that the the fused fluoride salts of Na-Li-Be as materials problems would take a very the tritium breeding medium. These long time to solve. salts would have to be contained in a nickel-base alloy. After listening to the Clausing initially worked with the problems of confining the plasma, Sherwood Project to solve problems of building magnets, particles bombarding welding, brazing, and fabrication hav- the surface of the plasma chamber, ing to do with the construction of etc., Manly said: “After listening to you fusion experiments. However, in a for two days, my thoughts are when relatively short time, he became in- you solve those problems, we will,fur volved, along with Dick Strehlow and the fused salt/nickel-base alloy prob- Bob Beacon, in the development of lem on a Sunday afternoon.” With the improved vacuum pumps for pumping intervening nearly 40 years of research, hydrogen. the plasma physics has proved to be This group made very significant im- much more difficult and has required provements in titanium sublimation much more time than originally antici- pumping technology. Clausing contin- pated. ued to work on the fusion program

reactor project years through the early 198Os, focusing on structural materi.als for j techniques for cleaning the first wall fusion reactors 65 and studying hydrogen recycle so as to reduce the amount of impurities in the Research and development (R&D) of plasma. structural materials for fusion reactors had its beginnings in June 1969, with Clausing and coworkers were the first a meeting to discuss technologies to use oxygen glow discharges to re- needed for the development of fusion move hydrocarbons followed by hydro- power reactors. Attendees at the meet- gen glow discharging to remove the ing included Herman Postma, Jim Weir, oxides formed during the oxygen clean- Bill Wiffen, Don Steiner, and Art Fraas. ing process. A surface analysis station Materials, specifically performance of for studying the composition of first materials in the neutron radiation and wall materials was designed and built chemical environment of a reactor, by Robert Clausing, Lee Heatherly, and were identified as the key or critical L. C. (Dot) Emerson. issue.

the surface analysis hfir irradiation station In 1970, the first irradiation experi- This surface analysis station was used ment funded by the fusion program on fusion experiments throughout the was initiated in the High Flux Isotope world, including T- 12, Kurchatov Reactor (HFIR). This experiment, con- Institute of Atomic Energy, Moscow ducted by Bill Wiffen, investigated the (June-July 1978); Doublet III, General effects of irradiation on the properties Atomics, San Diego, California (1978- of niobium alloys, envisioned at the 1979); TEXTOR, KFA, Jiilich, Germany time as the best choice for a structural (1982); and JET Joint Undertaking, material for a lithium- cooled fusion Culham, England (1983). reactor.

A second surface analysis station was 1976 oil embargo designed, built, and attached to the fusion devices located in Oak Ridge From 1974 to 1976, the U.S. Fusion including ISX, ISX-B, and EBT at Y-12. Program experienced a significant This occurred over a period of several expansion as a result of the oil -em- years during the late 1970s and early bargo and energy crisis. At this time, 1980s. materials and technology were elevated to mainstream components of the program.

reactor project years organization of the database required for design of the program reactor would be generated primarily in 66 fission reactors using techniques such In 1976, Dr. Klaus M. Zwilsky, Chief of as spectral tailoring. the Materials and Radiation Effects Branch of the Office of Fusion Energy, Spectral tailoring is a technique used to organized the Fusion Reactor Materials approximate irradiation damage in Program along four major task areas: austenitic stainless steels that will (1) Alloy Development for Irradiation occur in a fusion spectrum by irradiat- Performance (ADIP), (2) Damage Analy- ing in a mixed-spectrum fission reactor sis and Fundamental Studies (DAFS), and stepwise adding a thermal neutron (3) Plasma-Materials Interaction (PMI), absorber around the experiment to and (4) Special Purpose Materials reduce the thermal neutron flux. This (SPM). approach was initially suggested by Jim Horak of the M&C Division. Program plans for each area were prepared by Technical Task Groups development of alloys composed of personnel from the vari- ous Department of Energy (DOE) labo- Since there was no single alloy system ratories and contractors. that would meet the requirements of the various proposals for a commercial Chairmen of the four task groups were: reactor, it was viewed as necessary to (1) ADIP - James Stiegler, ORNL; have a parallel path approach for devel- (2) DAFS - D. G. Doran, Hanford opment of suitable structural materi- Engineering Development Laboratory; als. Initially, four paths were pursued: (3) PM1 - W. Bauer, Sandia National (1) austenitic stainless steels, (2) Laboratories; and (4) SPM - James nickel-base superalloys, (3) refractory Scott, ORNL. Other ORNL staff involved metal alloys, and (4) innovative con- in this early program planning process cepts (e.g., ordered alloys). were Everett Bloom and Bill Wiffen, of the M&C Division. As research results became available, the nickel-base alloys, niobium, molyb- The assumptions used in developing denum alloys, Fe-Ni-V ordered alloys, the program plans were (1) construc- and titanium alloys were dropped from tion of an experimental power-produc- the program. In the planning activity of ing reactor about 1990 and (2) a dem- the 197Os, it was envisioned that a onstration plant by the end of the fusion neutron source would be built century. Interestingly, it was assumed and operational about 1990 for the that the structural material would be development and qualification of alloys austenitic stainless steel, and the for the demonstration and power reac-

reactor project years tors. The fusion neutron. source .re- These designs were intended to feature mains a high priority for materials the potential advantages of fusion in R&D. the areas of maintenance, safety, and 67 radioactive waste as compared to fls- use of ferritic stee.1.s sion reactors.

At the outset of the program, it was The fusion reaction does not produce assumed that ferritic steels would radioactive nuclides, and it is not self- probably not be satisfactory as a fusion sustaining as is a fission reaction when reactor structural material because of a of fissionable material is their ferromagnetic properties. In the available: Any radioactivity produced in late 197Os, however, it became the fusion reactor derives from the apparent from experiments conducted capture of neutrons in the materials under the Liquid Metal Fast ,Breeder from which the reactor is constructed. Reactor (LMFBR) Program that this class of alloys exhibited excellent advantages of fusion over fission resistance to irradiation-induced ,_ The characteristics of any radioactivity swelling and high-temperature helium (e.g., type, half-life, biological hazard embrittlement, and this caused the potential, decay heat, and pathways for fusion program to reexamine their. I disposal) are dependent on the materi- possible use. als of construction. This leads to im- Design studies indicated that the field portant potential advantages of fusion perturbations introduced by the pres- in the areas of safety and environmen- ence of ferromagnetic structural mate-. tal impact, for it appears possible to rials would be small and that, although develop materials that are optimized ” they could not be ignored, the addi- from the viewpoint of safety (i.e., re- tional structural loads introduced by duced afterheat, reduced volatility, etc.) the action of the magnetic field on the and environment (i.e., reduced long- ferromagnetic structure could be ac- half-life radionuclides for safer disposal commodated. Thus, in 1978, the pro- and/or possible recycle). ’ gram began an evaluation followed by candidate structural materials an R&D effort on ferritic/martensitic (FM) steels.‘as potential structural Three material systems have the alloys. greatest potential to yield a structural material with attractive safety and fusion reactor design environmental characteristics: marten- In the late 197Os, Hopkins and cowork- sitic (FM) steels containing 9 to 12% Cr, ers at General Atomic began to study vanadium-based (vj“alloys, and silicon “low-activation” fusion reactor designs. carbide-silicon carbide composities

reactor project years (Sic/ Sic). Three structural material tion of carbon-carbon composite options are pursued for two basic plasma facing materials under the PM1 68 reasons. First, none of these three program. Walt Eatherly and Ray options has the physical, mechanical, Kennedy collected candidate carbon- and chemical properties to make it a carbon materials for irradiation in the viable candidate in all design options HFIR. Evaluations of the neutron irra- (i.e., coolant-breeder combination, diated carbon-carbon composites were operating temperature, wall loading, performed by Tim Burchell and etc.) Walt Eatherly.

Martensitic steels are most attractive in international fusion a water-cooled, ceramic-breeder sys- research tem. Vanadium alloys are the most attractive candidates for an Li or Li-Pb Fusion research has always been inter- coolant/breeder, and Sic/ Sic compos- national in nature. The was, ites are proposed for very high tem- of course, discovered in the U.S.S.R. perature, helium-cooled designs. Sec- Even in the early years, during the cold ondly, three options are being pursued war, scientific exchanges between because it is not clear which of the scientists in the United States and options can be developed to have ad- U.S.S.R. took place. equate properties for fusion power reactor applications. The first such exchange involving the materials program was that of an plasma facing Atomic Energy Commission (AEC) materials delegation traveling to Russia in No- vember 1974. Jim Horak of the M&C Early on it was realized that the plasma Division was a member of the delega- facing materials (first wall and tion. This trip laid much of the ground- diverter/limiter armor) would have to work for future exchanges and collabo- have remarkable properties: low atomic rations with the U.S.S.R. and subse- number, good thermal shock resis- quently Russia. tance, high melting temperature, and high thermal conductivity. For ma- In the early 198Os, primarily through chines such as ITER, neutron irradia- the efforts of J. L. (Jim) Scott, a signifi- tion stability would be a further re- cant collaboration was developed be- quirement. tween ORNL and the Japan Atomic Energy Research Institute (JAERI). In Graphite and carbon-carbon compos- this collaboration, irradiation experi- ites have been widely used as plasma ments are carried out in the HFIR. All facing materials. In the late 1980s aspects of the program are collabora- ORNL became involved in the irradia-

reactor project years tive, i.e., funding, planning, analysis, In 1975, the International Conference publication of results, etc. on Radiation Effects and Tritium Tech- nology for Fusion Reactors was held in 69 In 1995, the third phase, 1995 to 1999, Gatlinburg, Tennessee. Don’ Steiner of of this collaboration was initiated. The ORNL was general chairman, Warren Japanese universities, i.e., Monbusho, Grimes of Chemical Tec,hnology Divi- have had a collaborative program on sion and Jim Scott of M&C Division” fusion materials research that began served on the organizing committee, with experiments on the RTNS-II (Ro- and Bill Wiffen of M&C and Jack tating Target Neutron Source) at Watson of Chemical Technology Divi- Lawrence Livermore National Labora- sion served on the program committee. tory in the 1970s. In 1979, the First Topical Meeting on The focus of this collaboration moved to Fusion Reactor Materials, cosponsored the FFTF (Fast Flux Test Facility) and by the American Nuclear Society, DOE, the EBR-II (Experimental Breeder Electric Power Research Institute, and Reactor), and for Phase III (1995 to the Nuclear Metallurgy Committees of 2002) will involve experiments in the the American Institute of Mining, Met- HFIR at ORNL. allurgical, and Petroleum Engineers and the American Society for Metals, contribution of metals was held in Miami Beach, Florida. This and ceramics meeting was the predecessor of the personnel International Conference on Fusion Reactor Materials (ICFRM). Members of the Division have made valuable contributions to the eventual ICFRM-1 was held in Tokyo, Japan, in development of fusion not only through 1984; ICFRM-2 in Chicago, ; their contributions to fusion science ICFRM-3 in Karlsruhe, Germany; and technology and publication of this ICFRM-4 in Kyoto, Japan; ICFRM-5 in work in the open literature, but also Clearwater, Florida; ICFRM-6 in Strasa, through their participation in interna- Italy; ICFRM-7 in Obninsk, Russia, in tional workshops and the organization 1995; and ICFRM-8 will be held in of technical meetings and symposia. Japan. The first International Working Session on Fusion Reactor Technology was held Members of the Division have played in Oak Ridge in 1971. Don Steiner of key roles in the organization of each of ORNL was the organizing chairman, these conferences. ICFRM-5 was hosted and Bill Wiffen of the Division was on by ORNL with Everett Bloom serving as the organizing committee and a session general chairman. Others from the chairman. Division who contributed to the confer-

reactor project years ence organization included: Arthur required to make fusion a safe and Rowcliffe, chairman of the organizing environmentally attractive energy 70 committee; Louis Mansur, organizing source. committee; Tim Burchell, Ted Reuther, Pete Tortorelli, and Steve Zinkle, pro- Now, our challenge is to develop these gram committee; Ron Klueh, chairman materials so that they have the me- of the publication committee; Francis chanical properties, corrosion resis- Scarboro, secretary to the publication tance, and radiation damage resistance committee; Roger Stoller, publication to make fusion an economic energy committee; Phil Maziasz, publicity source. committee; and Judy McKinney, con- Today’s ORNL team has the mix of ference secretary and treasurer. youth and experience to do the job. looking ahead That team consists of the Structural Materials Group, the Irradiated Materi- ORNL has completed almost four de- als and Examination Testing Facility, cades of research toward the goal of the Carbon and Insulating Materials harnessing the energy that powers our Technology Group, the Corrosion Sci- sun-. Since the 197Os, ence and Technology Group, the Frac- materials and other technologies have ture Mechanics Group, and the Materi- been recognized as essential if this goal als Joining and Nondestructive Testing is to be achieved. Group. All are making major contribu- tions. We have made much progress in un- derstanding the effects of the fusion Other divisions who are collaborating operating environment on the proper- in these efforts include the Engineering ties of materials, and we have identified Technology Division, Research Reactors material systems that have many of the Division, and Fusion Energy Division., fundamental characteristics that will be

reactor project years gas-cooled reactors at ornl: thirty-plus years of history and progress.

characteristics of gas- since 1985. More recently, DOE has cooled reactors also supported studies of a modified version of an MHTGR for application to 71 Today’s High Temperature Gas-Cooled a New Production Reactor (NPR) for the Reactor (HTGR) design is a versatile production of tritium, termed the power reactor with a variety of attrac- MHTGR-NPR; the latter was selected as tive features that make it efficient and one of two NPR candidates in August safe. It is a thermal reactor that uses a 1988. Much of the base technology for graphite moderator, ceramic-coated the MHTGR and the MHTGR-NPR is fuel particles, and helium gas coolant. common to both reactors, including fuels, metals, and graphite materials Because it can attain high tempera- development. ORNL has been and tures, the HTGR can achieve high remains an important participant in thermal efficiencies using the steam- base-technology development, and the turbine (ST) cycle, the gas-turbine (GT) M&C Division has had and continues cycle, or combined cycles. It can also to have a key role in fuel and materials be applied to the cogeneration of pro- development essential to the success of cess steam and electricity or to fossil-’ the HTGR. fuel conversion processes for produc- ing hydrogen, ammonia, and metha- early days - the nol, and for converting coal to liquid experimental gas- and gaseous fuels. cooled reactor (egcr)

Because of the special properties of The first work on HTGRs in the U.S. graphite, helium, the fuel used, and was initiated by General Atomics (GA) the low power density of the core, the in about 1955. In 1957 Congress di- HTGR is inherently a very safe reactor. rected the Atomic Energy Commission By decreasing the power level of a unit (AEC) to initiate development work on a to 450 MW(t) or less, the peak fuel power reactor system that would com- temperatures during very severe acci- pete with the Magnox gas-cooled reac- dents can be limited to values where , tors being developed and built in the fission products are essentially re- U.K. A system using the inert gas tained within the core, an inherently helium as coolant was chosen as the safe configuration. best candidate for a high-temperature, high-efficiency system. The project was These latter units are termed,,Modular to culminate with the design, constmc- HTGRs (MHTGRs), and have been the tion, and operation of a 40-MW(e) focus of the USDOE HTGR program demonstration reactor at Oak Ridge called the Experimental Gas Cooled Reactor (EGCR). The project was thus

reactor project years identified as the mission for the sub- led to several test programs in which stantial reservoir of technology and the Division played a leading role: 72 talent on high-temperature materials at ORNL. 1. compatibility of structural compo- nents with graphite in a helium reactor design environment of controlled purity 2. mechanical properties testing of Furtherwork and study led to impor- materials under appropriate envi- tant decisions on materials and system ronmental conditions design. The reactor design selected was a graphite-moderated steam-generating 3. development of fabrication tech- system using stainless-steel-clad fuel niques for cored UO, fuel pellets, elements. The fuel rods would contain fuel rods, and other components, UO, fuel pellets similar to those used including the steam generators successfully in pressurized-water 4. irradiation testing of prototype fuel reactor systems. However, the fuel rods rods under controlled conditions were larger in diameter because of the lower specific power of a graphite- 5. development of nondestructive moderated system, and the UO, pellets testing techniques for the compo- were designed with a hollow core to nent materials. allow void volume for accumulation of materials compatibility fission gases. The work on materials compatibility role of the division was led by Jack DeVan, using facilities operated by the Reactor Division at Y- The Metals and Ceramics Division 12. Stainless steels and other alloys under the leadership of Bill Manly were exposed in contact with graphite assumed a major role in the project. in high-pressure helium at tempera- One of the Division’s important func- tures up to the maximum operating tions was to select and specify the temperature. The concern was that, in materials for components of the reactor the absence of oxidizing conditions, core and steam generators and to stainless steels might not develop a participate in the design of those com- protective oxide layer and, therefore, ponents. might corrode severely. This could lead to spalling of surface layers, contami- Materials and operating conditions nation of the system, and even struc- were selected by extrapolating from tural failure of the components. The well-documented technology. The major ‘tests were conducted at conditions task, then, was to demonstrate that the such that the impurities inherent in chosen materials would perform ad- the graphite would contaminate the equately at the design conditions. This helium in the system. Tests for up to reactor project years 5000 h demonstrated, however, that the specification of structural materials. protective layers did develop on the was the development of methods for 73 metal surfaces, preventing spalling and testing welded closures and for ensur- sample degradation. ing the integrity of the structural mate- rials themselves. This vital function . . Mechanical properties of the, type 304 was performed by the Nondestructive stainless steel cladding material were Testing Laboratory under the leader- tested in facilities set up and commis- ship of Robert Oliver and Robert sioned at ORNL by Don Douglas and McClung. The group perfected and Jim Weir. An important part of this demonstrated procedures that were testing program involved creep-rupture incorporated into specifications for the tests of prototype fuel rods. reactor components. design of fuel irradiating prototypical elements fuel elements

The design of the fuel rod, with a cored A vital element in testing and demon- UO, fuel pellet presented special fabri- strating the performance of the fuel cation problems that were. addressed element was the successful irradiation and solved by Al Taylor and Robbie testing of prototypic fuel elements. An Robbins of the Ceramics Laboratory. extensive testing program was con- The initial effort to produce pellets ducted by the Irradiation Testing Group within the tolerances of density and of the Reactor Division under the lead- dimensions without supplemental ership of Don Trauger. sizing operations was only partially successful. Facilities at the Engineering Test Reac- tor (ETR) and the Oak Ridge Research Other fabrication problems that were Reactor (ORR) were used to test addressed and solved included the prototypic fuel rods at design tempera- methods for sealing the fuel rods and tures and to maximum fuel burnup. for fabricating the steam generators. These problems were addressed by the The Division prepared the test speci- Welding Laboratory under the leader- mens, conducted postirradiation ex- ship of Pete Patriarca and aminations, and interpreted the re- Gerry Slaughter. sults. The tests employed partially enriched UO, pellets that had been development of weld fabricated by the Ceramics Laboratory. testing methods These pellets were loaded into carefully inspected capsules that were short- An important supporting function for length versions of a typical fuel rod. the work on component fabrication and

reactor project years The irradiation testing program demon- The result was a lack of interest and strated that, although the pellets devel- participation by industry and this was 74 oped radial cracks during irradiation, a major factor in the cancellation of the the resulting structure was stable. project in 1964. Construction was Therefore, the fuel rods were expected completed and the fuel was delivered to perform adequately as designed. and on site when the decision was made to stop work. Thus, no operating development of fuel experience was gained on the system in element specifications spite of the vast efforts expended in the development and testing programs. The results from all the fabrication and testing programs were used to develop then and now - the htgr specifications for the fuel elements and other components. The fuel element Aside from the EGCR concept, early specifications were prepared under the work at ORNL involved the evaluation leadership of John Coobs, and data of coated p&-ticle fuels for pebble-bed from the Welding Laboratory were used gas-cooled reactors (PBRs). During in preparing specifications for the 1960 several PBR design studies were steam generators. carried out, and experimental work began on coated-particle fuel develop- Completion of the fuel element specifi- ment and performance. cations was followed by awarding a contract for fabrication and delivery of Although work on a proposed PBR the fuel elements. The vital function of experiment was terminated in 1963, monitoring the performance of this the coated fuel development and fission contract was completed by Gerry product behavior efforts started under Tolson, and the fuel elements were that program were continued as part of delivered on schedule. the Gas-Cooled Reactor Program (GCRP). That effort was for HTGRs constructing the using prismatic block fuel elements reactor (i.e., prismatic graphite blocks contain- ing coolant holes and fuel holes, with The Title II design and construction of fuel rods located in the fuel holes, the reactor and auxiliary systems Fig 7). proceeded about as scheduled. However, the reactor concept was Work on fueled-graphite development perceived by the nuclear industry as and associated fission-product behav- competing directly with its PWR and ior has continued since that time, with .- 1_ BWR systems, which had evolved from the M&C Division playing a vital role in a base of technology developed for the the development of high-quality coated- nuclear submarine reactors. fuel particles. Since 1986, ORNL has

reactor project years 75

Fig. 7. Discussing product of device for automated fabrication of green HTGR fuel rods. Left to right: T. N. Washburn, Manager Fuels and Processes Section, Metals and Ceramics Division, ORNL; T. A. Nemsek, DOE; R. A. Bradley, Fuel Cycle Engineering Group, Metals and Ceramics Division, ORNL; W. 0. Harms, Director, LMFBR Programs, ORNL; E. A. Womack, DOE. been the “lead laboratory” for HTGR the latter case, the coatings failed from base-technology development; previ- “bridging” and associated stresses ously, base-technology development ’ during fuel irradiation. was shared between General Atomics Jim Scott of the M&C Division was and ORNL. heavily involved in this work. In the contributions of t,he, 1970s and 1980s key facilities were division to the project developed for determining the perfor- mance of high quality fuel. ORNL, One of the many important contribu- particularly the M&C Division, pio- tions made by the M&C Division in the neered the development of equipment 1960s was the demonstration that. ~ ,. ,x, .._ and procedures for examination of coated fuel particles needed to be individual irradiated coated particles. distributed within a carbonaceous matrix to form a fuel rod, rather than These included use of electron micro- loaded directly as coated particles. In probes, scanning electron microscopes,

reacfor project years gamma spectroscopy, and postirradia- Reactor Vessels (PCRVs). The applica- tion gas analyzers. Mike Kania, Ken tion of low-power MHTGRs has subse- 76 Valentine, Ernie Long, and Terry quently resulted in use of steel reactor Lindemer made key contributions to the pressure vessels rather than PCRVs. above. metals studies ORNL analysts, with major contribu- tions from the M&C Division and in Key metals studies, led by Herb McCoy collaboration with scientists from Gen- and Joe Strizak, have included obtain- eral Atomics and the Research Center ing mechanical,. propertyL1. information_ ., on in J-iilich, Germany, quantified major metals of interest as a function of failure mechanisms for coated-particle temperature and environment. The fuels. ORNL scientists from the Chemi- development of a large number of cal Technblogy Division materials test rigs in cooperation with (Terry Lindemer) and M&C Division other materials programs in the M&C (Bob Lauf) predicted the phases present Division contributed significantly. in oxide, carbide, and oxycarbide fuel A subsequent key development was the kernels as a function of initial composi- ability to control impurity levels in the tion and burnup. 0 simulated coolant environment seen by These predictions have been matched the metal specimens by adding impuri- with qualitative metallographic results ties from a “tank farm” without the to develop fuel models explaining how need for a large volume of hot graphite these phases influence kernel and or a recirculating loop to maintain a coating performance during irradiation. proper environment. Recent materials development within the M&C Division other htgr work is providing data on the performance of reactor vessel steels at the tempera- In other HTGR work in the early 196Os, tures, neutron exposures, and neutron ORNL performed reactor physics analy- spectra representative of the MHTGR. ses and fuel-cycle evaluations and ’ Mechanical property data also continue participated with General Atomics in to be obtained for alloys to be used in reactor physics arid fission product the heat transport system, steam gen- behavior measurements in the Peach erator, control-rod cladding, and other Bottom HTGR (the first HTGR built in metal internals of the reactor. the United States). expansion of the htgr Also, ORNL performed design and fuel- program cycle evaluations of large HTGRs, evalu- ated graphite behavior, and in 1966 The HTGR program expanded in 1970 initiated work on Prestressed Concrete when the Thorium Utilization Program

reactor project years i ,r , j..__:

was incorporated and dedicated to kernels and coatings, and a reference HTGR fuel-recycle development; head- fuel-recycle particle was recommended end reprocessing and fuel refabrication and adopted by GA. Overall, M&C development were emphasized. A. L. personnel helped develop fuel-recycle (Pete) Lotts headed that effort from the equipment and processes, evaluated start. Nearly all the fuel refabrication fuel cycle performance, irradiated efforts were carried out by the M&C candidate fuels for recycle application, Division. and evaluated fuels for recycle application. Remotely maintained “coaters”, were developed for coating fuel kernels, and experimental graphite .” the “slug-injection” process was devel- development oped for remote refabrication of HTGR .I fuel rods. John Sease led these impor- The continuing ORNL experimental tant developments. In the slug-injection graphite development program for the process, a mixture of coated fuel par- HTGR began in 1974. Important M&C ticles and graphite particles was Division studies performed under Walt poured into a mold, and a solid “slug” Eatherly and Ray Kennedy were the of cold matrix material (pitch and irradiation behavior of graphite, irra- graphite powder) was placed above the diation creep measurements, oxidation particles. After heating, the “molten studies, and measurement of physical slug” was injected into the particle bed; properties using eddy-current and cooling resulted in a removable fuel sonic-velocity measurements. rod. Numerous grades of graphite were irradiation testing tested, and their mechanical and physi- program cal properties were measured before and after irradiation. The statistical Various HTGR particle-fuel types were variation in physical and mechanical irradiation tested by the M&C Division properties within and between graphite with assistance from the Engineering billets has been quantified. Tim Technology Division; key M&C scien- Burchell has led the more recent tists and engineers involved were Frank graphite studies. Homan, Ernie Long, Terry Tiegs, and Mike Kania. project termination

The irradiation testing program in the Technology development activities were 1970s supported both HTGR base- terminated at the end of FY 1995. technology and the HTGR fuel-recycle Closeout and cleanup efforts were programs. Various fuel particles were supported in FY 1996 and 1997. tested involving various types of

reactor project years space nuclear programs

The programs on developing nuclear by the resolution of fuels and materials power systems for space constitute the limitations. Because the coolants and 78 longest continuing activity utilizing the working fluids in these systems used Division’s expertise in mechanical mercury, sodium, potassium, or properties, materials joining, corrosion lithium., the expertise in the Division in and other disciplines developed during liquid-metal corrosion developed during the Aircraft Nuclear Propulsion Pro- the ANP Program placed us in a strong gram from 1950 through 1960. position to address these issues. Dur- ing this period, the Division was a Starting in the early 196Os, a number leader in the design, fabrication, and of space nuclear reactor programs operation of static, refluxing, thermal evolved under Bill Harms and William convection, and pumped-loop systems Thurber until their abrupt termination for the characterization of the compat- in 1973. These included a series of ibility of alkali metals with stainless Space Nuclear Auxiliary Power (SNAP) steels and refractory alloys. Programs - SNAP 8, SNAP 50, SNAP 10; ORNL’s Medium Power Reactor By 1968, ORNL had accumulated over Experiment (MPRE); and NASA’s Ad- 100,000 h experience with stainless vanced Lithium Reactor Program. steel systems containing boiling potas- Approximately ten years after their sium or circulating sodium or lithium. termination, activities on space reactor This experience evolved into the design materials technology began again and operation of alkali-metal corrosion under R. H. Cooper with the SP- 100 tests of refractory alloys of niobium, Project and the Multimegawatt (MMW) tantalum, and molybdenum and bime- Space Power Program. tallic systems made up of both stain- less steels and niobium or tantalum- early snap reactor based alloys. From these activities, the programs M&C staff identified the role of impuri- ties in potassium and sodium that Starting in the early 196Os, the country control the life-limiting compatibilities had a growing commitment to creating involving stainless steels and refractory a human presence in space. This com- alloys. This experience led to identify- mitment established the need for a ing the performance-limiting role of reliable source of electric power in oxygen in the compatibility of niobium space and created a number of space and tantalum alloys with lithium. reactor programs. ORNL’s major inter- est was in liquid-metal-cooled fast In support of these alkali-metal testing reactors tied to the Rankine power activities, the predecessor to the Mate- conversion cycle. Achieving the design rials Processing Group led in develop- objectives of these programs was paced ment of methods for melting and fabri-

reactor project years cation of complex components from facture thin-wall, small-diameter tub- such tantalum-based alloys as T-l 11 ing from tungsten, tungsten-rhenium 79 and ASTAR 8 11C and niobium-based alloys, and tungsten-thoria alloys. alloys as Nb-1% Zr, FS-85, and D-48. Paralleling this effort was development The Welding and Brazing Group devel- of chemical vapor deposition methods oped specialized laboratory and field to produce small-diameter tubing and methods for joining refractory alloys to sheet from tungsten and tungsten avoid alkali-metal compatibility and alloys. The high-temperature mechani- mechanical property problems. cal properties of products produced by both methods were evaluated exten- Another major role of the division was sively during this period. These activi- in characterizing the mechanical prop- ties were initiated in support of the erties of the high-temperature struc- SNAP reactor concepts but later were tural materials used in these systems. applied to the fabrication of high- performance emitters for thermionic The designs of the SNAP 50 and, the converters considered for space appli- advanced lithium-cooled reactors were cations coupled to either reactor or based on the use of uranium nitride isotope heat sources. fuel due to its high thermal conductiv- ity and uranium metal content. How- sp-100 project ever, in the early phases of these pro- grams, other organizations encountered The creation of the Strategic Defense unpredictable swelling and fission gas Initiative (SDI) in the early 1980s es- release in the manufacture off reliable, tablished needs for space-based sur- uranium nitride fuel. ORNL developed veillance and weapons systems requir- and demonstrated a hydride-dehydride- ing long-lived, reliable sources of elec- nitride process for the manufacture of, trical power. The need for systems high-quality fuel. This process provided requiring power ranging from tens of the control of trace elements and nitro- kilowatts to hundreds of megawatts gen purity necessary to achieve consis- rekindled the space nuclear reactor tent irradiation performance. power program in 1983. The first of these programs was the SP- 100 Project, Another major activity during 1966 to which was oriented toward the develop- 1973 was the optimization of tungsten ment of a system providing approxi- and tungsten-alloy fabrication meth- mately 100 kW of electric power. The ods. During this period, we developed a project, which began in 1983, focused unique duplex extrusion. process for on niobium-based alloys, in particular fabricating high-quality tungsten and on the characterization of the high- tungsten-alloy tubing. The efforts temperature mechanical properties, demonstrated the capability to manu- fabrication optimization, and charac-

reactor project years terization of oxidation and alkali-metal stainless steel. Later, we were called compatibility. upon to develop an eddy current 80 method for inspecting the coolant multimegawatt space passages in the NERVA reactor’s beryl- power program lium reflector and to characterize the outgassing properties of reactor fuel. As The need for space-based systems with the nuclear electric reactor pro- capable of providing hundreds of mega- grams, the NERVA program was termi- watts of power resulted in the initiation nated in 1973. of the Multimegawatt Space Power Program in 1985. Although the pro- isotope power program gram was in existence for only four years, it provided opportunities to This portion of the space power pro- initiate broader activities in the area of gram began around 1967 under Ralph refractory alloy mechanical property Donnelly and Tony Schaffhauser and testing, fabrication, and compatibility continues today. In the 1960s the testing. During this period, we devel- materials program was diverse, sup- oped a materials properties handbook porting characterization of molybde- focused primarily on tantalum-, molyb- num, tantalum, and superalloys for a denum-, and tungsten-based alloys broad range of mission applications. In and fabricated the first thin-wall, practically all cases, these alloys were small-diameter tubing of the tantalum evaluated as candidate claddings for alloy ASTAR 8 11 C. isotope power system using plutonia or curium oxide fuels. As a result of these space nuclear early activities, the Division manufac- propulsion programs tured fuel cladding materials used in two Lincoln Experimental Satellites and A major emphasis of the country in the one Pioneer Satellite. mid- to late 1960s was the development of nuclear rockets for space. The major In the early 197Os, the Isotope Space focus of these efforts was the NERVA Power Program desired fuel cladding and Rover Programs. Although the materials with better high-temperature NERVA Program never represented a strength, ductility, and oxidizing major piece of work for the Division, tolerance than could be provided by our alloys, high-temperature testing, molybdenum and tantalum alloys. nondestructive examination, and fuel From these objectives, development expertise were utilized. Initially, we focused on platinum, tungsten, and characterized the mechanical proper- iridium-based alloys began In 1973, an ties of candidate nozzle materials, iridium alloy containing about 0.3% which included Inconel and type 347 tungsten appeared to show the best

reactor project years potential. The Division used this alloy the metallurgical quality of the to fabricate the fuel cl*adding for the materials while reducing the unit cost. isotope power systems used on the 81 Voyagers 7 and 8 missions during the Efforts began again in 1990 to mid- 1970s. Continued alloy manufacture fuel cladding for NASA’s development activities under C. T. Liu Cassini Mission now scheduled to led to the iridium DOP-26, alloy, which launch in 1997. contained 0.3% tungsten and parts per In the late 1970s we optimized the use million quantities of thorium and of a low-density carbon-carbon com- aluminum to improve ductility at high posite invented by the Y-12 Plant for strain rates. Manufacture of iridium use as a thermal insulator in isotope alloys was resumed with some power systems. The material, carbon- improvements in the 1980 to 1983 bonded carbon fiber (CBCF) is made by period to fabricate the fuel cladding bonding short carbon fibers with a used for the isotope power system on phenolic resin and then carbonizing the NASA’s Galileo Mission, launched in composite. This optimization has pro- 1989, and on the European Space vided hardware flown on the Galileo Agency’s Ulysses Mission, launched in and Ulysses missions and to be flown 1990. From 1983 to 1990, the process on the Cassini mission in 1997. for fabricating the iridium DOP-26 alloy fuel cladding was enhanced to improve

reactor project years advanced test reactor

The Advanced Test Reactor (ATR) is a Oak Ridge National Laboratory suc- 250-MW reactor located at Idaho Engi- cessfully developed a fabrication pro- 82 neering Laboratories, Idaho Falls, cess using a U,O, dispersion in 6061 Idaho. The core is in the shape of a aluminum. Using only three powder four-leaf clover to provide a maximum metallurgy dies with various ratios of number of irradiation facilities. The fuel longitudinal and cross rolling yielded elements are pie shaped at a 45” angle. the 19 acceptable plates. This requires 19 fuel plates, each a different width. The fuel plates are The plates were attached to the side 49.5 in. long but vary in width from plates using, for the first time, a con- 2.136 to 3.974 in. stant pressure, dual-head, roll-swaging operation. To help equalize pressures, Because of our experience in develop- staggered holes 2 in. long and three ing the High-Flux Isotope Reactor fuel plates wide were machined across the element, the Department of Energy side plates. gave responsibility for developing fabri- cation techniques for these ATR ele- The first 19 fuel elements were made at ments to the Metals and Ceramics ORNL with depleted U,O, and were Division. The project was directed by used for hydraulic tests. At that time R. J. Beaver. the fuel was changed to U Al, and the process transferred successfully to a commercial fabricator.

reactor project years molten-salt power reactors

The molten salt reactor technology the fluoride salts are reasonably ag- drew heavily from the work done in gressive toward chromium. support of the Aircraft Nuclear Propul- 83 Further, an alloy to operate in fluoride sion (ANP) Project.’ The earlier ANP salts did not need high chromium for work demonstrated the basic chemical ^ ‘good odd&ion resistance, but.the air compatibility of the graphite, lithium side of a reactor vessel would require fluoride-beryllium fluoride salts, moderate resistance to oxidation. Thus, and high-nickel structural materials. ^ the concentration of chromium. was .a .-, The uranium fuel,was present in the compromise of 7%, which gave accept- form of uranium tetrafluoride, which able corrosion resistance in air and in was soluble in the salts just mentioned. fluoride salts. The physics of the system was gov- erned largely by the geometry of the Corrosion considerations also dictated graphite and the composition of the that the alloy be based on nickel rather salt. The heat generated in the fuel salt than iron. Phase diagram studies had by fissioning was removed by contact -’ . shown that several percent of molybde- with a non-uranium-bearing coolant num was soluble in nickel, so this salt. The heat in the coolant lsa.hcoul”d.. highly refractory element was added to be used to make steam for the genera- give the alloy good strength. The alloy tion of electricity, for waste heat appli- selected on the basis of detailed re- cations, or for other processes. search and applied experience had the nominal composition of Ni-7% Cr4% A demonstration reactor was pesigned, Fe-16% MO. built, and operated at ORNL. This ” reactor was named the M~oltenSah This was a new alloy, and its produc- Reactor Experiment (MSRE) and began tion in large heats and complex shapes operation in 1965. The reactor pro- required considerable work on.. the part duced about 8 MW of thermal energy, of several commercial alloy vendors and which was dissipated through an air- of M&C metallurgists. Commercial cooled radiator. Numerous sk,iIl,s,.were names of INOR-8, Hastelloy N, and needed, so personnel from several Allvac N were applied to the alloy. divisions were involved, but materials- related problems were numerous, and The sizes and, low permeability require- the Metals and Ceramics (M&C) Divi- ments of the core graphite required sion personnel under the direction of , that it be produced by special methods, Jim Weir and Herb McCoy were heavily and these were monitored by M&C involved. personnel. A surveillance program allowed samples of metal and graphite Most nickel-base alloys contain fairly- to be removed periodically from the large concentrations of chromium to reactor for examination (Fig. 8). impart good oxidation resistance, but reactor project years Fig. 8. In-reactor surveillance irradiation experiment to be placed in the Molten Salt Reactor Ex- periment. The purpose was to determine the compatability of Hastetloy N and graphite under irradia- tion and molten salt corrosion conditions. (left to right, Arnold P. Litman, Charles E. Sessions, W. Howard Cook, C. Ray Kennedy, John W. Roger, and Ron L. Beatty). The MSRE operated for more than period of 1970 to 1976, some develop- 20,000 h from 1965 to 1969. The ment.was carried out relative, to mol-..,. I, reactor was run as an experiment, and ten-salt breeder reactors. The primary 85 members of the M&C Division were salt contained uraniu,m and,. thorium, _I part of the research team that was so it servec! 3s t@ .fe~i,le,,~~.~,~~~~l,~ . ,-$, ~~, concerned with the day-to-day opera- material. The.fission products were to tion. During the operation of the MSRE be kept at an acceptable level by gas and other associated research, several purging and by bismuth metal extrac- important observations were made. tion. A secondary coolant salt was to transport the heat from the core to l The reactor operated well and dem- produce steam for electricity genera- onstrated the basic compatibility of tion. the new metal alloy-graphite-fluo- ride salt system. The breeder concept presented several new materials problems, including . The reactor could operate on nu- (1) development of a graphite with merous fuels including several improved resistance to irradiation, isotopes of uranium and plutonium. (2) development of a nickel alloy with

l The new nickel-base-alloy was improved resistance to neutron irradia- embrittled by neutron irradiation. tion and penetration by fission product tellurium, and (3) development of mate- l The new nickel-base alloy was rials for containing the liquid bismuth penetrated and embrittled t.o a very used for fission product removal. Rea- short depth by the fission product sonable progress was made in each of tellurium. these areas by M&C personnel, but Since chemical methods had,been ., resources were not considered ad- developed for extracting the fission equate to continue work on this reactor products from the fuel.salt, the poten- concept. In 1976, work ceased on tial of molten-salt r.eactors as breeder molten-salt development at ORNL. reactors was recognized. Over the

reactor project years high flux isotope reactor program

The High Flux Isotope Reactor (HFIR) is 100 MW. This power is generated an ORNL reactor providing an intense within a volume the size of a small 86 neutron source. Its main objective is to garbage can. Aluminum is the produce research quantities of transu- structural material for all core ranium elements, permitting scientists components. The reactor was designed to explore the properties of these ex- and developed and is still being ceedingly rare elements. The reactor operated by ORNL after going critical in also provides highly active elements for 1965. During the initial design, medical use and reasonably sized, very development, and procurement phases, high neutron flux research facilities. At the project was directed by the time the reactor went critical, it Charles Winters. He was followed by provided the highest flux then available Al Both for procurement, construction, to engineering researchers.

The reactor design is based upon a flux-trap principle with a central cylindrical island containing tubes of the transu- ranium isotopes being irradi- ated. The tubes are surrounded by a light-water-moderated- and-cooled fuel region consist- ing of two annular fuel elements (Fig. 9).

The fuel core is surrounded by a thin, two-cylinder control region and a beryllium reflector. The desire to minimize development, capital, and operating costs led to the selection of aluminum- clad fuel plates, normal water coolant and moderator, and a beryllium reflector arranged in a cylindrical core.

As designed, the reactor produced a flux of 5 X 1015 neutrons cm-2 s-l with an average power density of Ffg. 9. Fuel element for the High Flux Isotope Reactor. 2000 kW/L and a total power of

reactor project years and the initial phases of reactor eluded Metal Forming under Richard operation. Beaver, Carl Leitten, and Bill Martin; Metallography, Robert Gray; Nonde- 87 The Metals and Ceramics (M&C) Divi- structive Testing, Robert McClung; sion played a major role in the develop- Powder Metallurgy, Joseph Hammond; ment and fabrication of all reactor core Remote Fabrication, A. L. (Pete) Lotts components. A large program within and John Sease; and Welding and the Division during the 1960s con- Brazing, Gerald Slaughter. The M&C sisted of three separate efforts, all Program Manager for the conceptional including both conceptual and produc- stages was Al Taboada, followed by tion development. George Adamson, assisted by Richard Beaver (Fig. 10). These included (1) fuel elements, (2) control rods, and (3) target rods. The HFIR was a challenging, interest- The M&C laboratories involved in- ing, and logical program for the M&C

Fig. 10. Some people involved in the development of the HFIR. (Left to right foreground) George Ada-on, Dick Beaver, and Al Both.

reactor project years Division. It was based on work previ- 3. fabricating and forming the plates ously accomplished during the develop- to tight dimensional tolerances and ment of smaller research reactors, with a low blister and nonbond reported in other articles in this series, rejection, but required a considerable extrapola- tion of the technology. 4. joining fuel plates into an element with reliable bonds and uniform The M&C contributions on fuel and water channel spacing, and control elements are presented below. Target fabrication is the subject of a 5. design, development, and fabrica- separate article. tion of dies and fuctures suitable for . industrial production. fuel elements With the use of aluminum as the struc- The aluminum fuel core for this reactor tural material and the high average consists of two concentric, aluminum- power density, 2000 kW/L, one of the base fuel elements, the inner contain- prime design and material problems ing 171 curved plates and the outer was temperature control, especially 369 plates (Fig. 9). Uniform cooling is control of hot spots. The development assisted by the plates being formed into of fuel cores, consisting of powdered an involute configuration providing the U,O, in powdered aluminum in a con- maximum exposed plate surface with figuration with a nonuniform fuel water channels of uniform width. The thickness across the width, went a long fuel plates are welded to tubular side way in reducing flux peaking and plates from the reverse side. The major thereby the maximum plate tempera- materials problems with the HFIR fuel ture (Fig. 11). Bill Foster of M&C and core faced and solved by the M&C b Reynolds -of the Instrumentation and Division fell into the following catego- Controls Division (I&C) jointly devel- ries: oped a through-transmission, x-ray attenuation instrument that could 1. meeting very tight uranium content measure and plot such uranium con- specifications for spots as small as centrations across an entire fuel plate. 0.080 in. in diameter with a fuel core having a nonlinear profile To yield the desired stronger fuel across the plate, plates, 6061 aluminum is used .as both the frame and cover plate material. Use 2. fabricating stronger fuel plates than of such an alloy, however, caused are normally obtained with conven- increased nonbond and forming prob- tional 1100 aluminum base plates, lems. Obtaining acceptable nonbond

reactor project years ORNL- DWG 64-4971 89

-- “““l “. -- 4C +Al .= . .. . -

.- -. ------. - M- --.Q Lko. + Al- -.--y ------u-n ICI AhIn- L

Fig. 11. Cross section through fuel plates, showing curvature to help cooling and fuel loading to reduce flux peaking.

yields required the development of a plates necessary to meet the tight new 6061 aluminum cleaning tech- plate-spacing requirements. Forming nique . utilizes a low-pressure marforming operation in which a formed steel die, The powder-dispersion fabrication presses the plates into a polyurethane practices, the aluminum cleaning pad. techniques, and the homogeneity scan- ner have all become the basis of tech- Variations in curvature across and, niques now used worldwide for the especially, along a plate, were the usual fabrication of aluminum-base fuel problem, which was ultimately solved plates. by incorporating a 20% cold-working sequence and a dead, soft anneal as a A problem that caused many head- final step. aches and one of the last to be solved was that of obtaining uniform and The most difficult operations in the reproducible curvature in the formed HFIP fabrication, are assembly and

reactor project years welding. The major problem is to as- was a costly operation, but after fabri- sure a reliable plate tie-in while con- cation of 200,000 fuel plates, except for 90 trolling weld shrinkage. The weld sharpening, the majority of the original shrinkage affects both the overall tooling is still being used. dimensions of the annular element and water channel spacing. Fuel plates are control plates slid into grooves machined in tubular The HFIR reactor control system is side plates and are partially held in unique since it consists of two cylindri- position by strips of Teflon filling each cal arrangements of plates located channel. between the fuel core and the beryllium The plates are attached by welds made reflector. The cylinders are 66 in. long, in grooves cut into the opposite side of l/4 in. thick, and approximately 18 in. each tube. The edges of the plates, in diameter. which do not contain fuel, protrude into these grooves and are fused into The inner cylinder is formed from four the side plates. Completely automatic plates welded together, while the outer tungsten inert gas welding procedures has four plates that are mechanically with specially designed heads are used. attached to each other. Each plate consists of four regions of differing Each element contains 96 circumferen- neutron absorber characteristics. Both tial welds yielding 25,920 joints. After ends are all aluminum and therefore welding, to show that the water chan- transparent to neutrons or “white.” nels have not been deformed, every channel spacing is measured and The center contains two regions of recorded. This is accomplished by a differing absorption: a short “grey” five-coil, eddy-current thickness gage section from a dispersion of tantalum inserted into five specified tracks down powder in aluminum and a longer the length of every channel. “black” section from a dispersion of europium oxide in aluminum. All parts Under the direction of Rodney Knight are clad with 6061 aluminum, and all the fabrication techniques developed at except the “black” section contain 1/4- ORNL were successfully transferred to in. holes on l-in. centers for pressure two commercial fabricators, first to equalization. The primary materials Texas Instruments in Attleboro, Massa- problems involved fabricating these chusetts, and then to Babcock and large composite plates to close toler- Wilcox of Lynchburg, Virginia. An ance (and free of nonbonds) and then important portion of the original work forming them into cylinders. at ORNL and Texas Instruments was the development and testing of the The forming was complicated by the many dies and furtures required. This brittleness of the europium oxide-

reactor project years aluminum matrix core. The materials achieved by stacking smaller ones in efforts were managed by Richard Bea- three layers. With the many joints, it 91 ver with the fabrication by M&C Divi- was necessary to condition the eu- sion and the explosive forming jointly ropium oxide and to weld and evacuate _ with the Y-12 Plant. the cores before both hot straight and cross rolling were used to obtain the The large plates were fabricated in ,a* large dimensions. single operation, with the large cores

reactor project years fabricating targets for the high flux isotope reactor . ._ . The fiFIR target elements provide can that has a short hexagonal section targets of various transuranium ele- for positioning the target element in the 92 ments for irradiation in the flux trap target assembly. Development activities region of the HFIR to produce research for fabricating the target elements quantities of transplutonium elements, centered around the blending and such as , curium, and cali- dispensing techniques of the aluminum fornium. The target assembly for the and transuranium oxide powders used HFIR consists of 3 1 target elements 35 in cold pressing the target pellets and in. long with an active length of 20 in. welding the end closures.

In the reactor the target assembly is Other developments included a nonde- centered in the fuel assembly, and structive eddy current inspection tech- individual target elements are irradi- nique for determining the sheath-to- ated for about 18 months. Initially the can spacing and forming and machin- transuranium target material was ing techniques for preparing the finned 242Pu. Subsequent targets were fabri- target tubes and target cans with the cated from transuranium materials hexagonal positioning area. Because of with higher atomic number reprocessed the extremely high background irradia- from the initial targets. M&C involve- tion levels (> lo4 rad/ h) that would be ment was the development of the pro- encountered in fabricating target ele- cesses for making the initial plutonium ments with reprocessed targets in a glove box fabrication line transplutonium materials, specialized and the development of the processes processes and equipment were devel- and equipment for fabricating the oped for remotely fabricating the tar- 1 transplutonium targets elements in a gets. remotely operated and maintained hot cell facility. Because of concern for contaminating the outside surfaces of the target ele- In the target elements the transura- ments during fabrication, all HFIR nium materials are present as l/4-in.- targets have been fabricated by the diam pellets of metal oxides in an 1100 technique proposed by Sloan Bomar aluminum matrix . The 20-in. active and A. L. (Pete) Lotts for pressing the target length requires 35 individual tranuranium-aluminum powder mix- pellets. The target pellets are sheathed ture in a section of an aluminum tube in an extruded 3/8-in.-diam partially with pure aluminum powder ends. finned 8001 aluminum tube with welded end fittings. The blending and dispensing of the very dense and relative coarse The fins position the target tube within transuranium oxide powders with a 5/8-in.-diam 8001 aluminum cover aluminum powder was a significant ~

reactor project years problem in the fabrication of targets for below atmospheric and, welding at irradiation testing and early targets. atmospheric pressure. The weld joint 93 The transuranium oxide must be design allows the establishment of a dispersed uniformly within the 35 mechanical seal before welding. Be- pellets of the active target zone because cause of the success of the final closure _, of the high heat generation and burnup weld, both end fitting welds have been the targets must withstand during their made with decreased internal pressure. 18-month residence in HFIR. After some 25 years HFIR targets are The blending and dispensing technique still being made by essentially the same developed by John Sease uses a minia- equipment and processes developed in ture double cone blending vessel with the mid sixties. The development of the a vibratory feeder for dispensing. It has remotely operated equipment was a been very effective making very uniform major effort by Central Engineering and HFIR targets pellets. The dispensing M&C, and the fact that much of this hopper must be isolated from the equipment is still functioning in an vibratory feeding mechanism. extremely hostile environment is a testament to the design effort headed The end-closure fusion weld developed by Ken Preston with support of the by Joe Eve and John Sease for the K-25 engineering group. Over the last HFIR targets uses a unique integral 25 years several hundred targets have tiller metal joint design. The major been fabricated remotely in Building problem in welding development was 7920 hot cells at ORNL. Many M&C porosity in the final closure caused by personnel have been responsible for the expansion of the helium gas contained successful fabrication of the HFIR in the closed aluminum target tube. targets, including John Van Cleve, L. C. Williams, and Edward Cagle. This problem was solved by reducing the pressure inside the target tube

reactor project years heavy-section steel technology and irradiation

The reactor pressure vessel in pressur- to the improvement of means for evalu- ized-water and boiling-water reactors ation and factors that may affect the nil 94 provides the primary line of defense in ductility transition temperature and the event of an accident. In the 1950s the propagation of flaws during vessel and 196Os, increased recognition of the life. . . . incorporating in many reactors importance of small flaws, which exist the design approaches whose develop- in all engineering structures, to frac- ment is recommended above.. . n ture resistance led to major interest and advances in the new field of frac- The Pressure Vessel Research Commit- ture mechanics. Because the reactor tee (PVRC) of the Welding Research vessel is subjected to degradation by Council prepared a research program neutron irradiation and potential rapid that responded to the recommendation cooling in certain kinds of accidents, of the ACRS letter. In June 1966, the and because it serves such a critical PVRC presented its program to the AEC function, the application of fracture staff and suggested that ORNL might mechanics to those vessels assumed be a satisfactory organization to admin- paramount importance. ister the program. Testimony to the AEC interest in the concept of a HSST The Heavy-Section Steel Technology program was provided in May 1966 (HSST) Program is probably the longest when it authorized ORNL to procure running research and development test material for groups participating in program at ORNL and is certainly the planned fracture-mechanics programs. oldest program funded by what is now The PVRC Program Plan was modified the Nuclear Regulatory Commission. by AEC to include irradiation effects The HSST Program was formally con- and elastic-plastic analysis, and, on ceived in a November 24, 1965, letter March 17, 1967, the HSST Program from the Advisory Committee on Reac- was officially authorized for $8.3 mil- tor Safeguards (ACRS) to the U.S. lion and for a term of 6 years. Atomic Energy Commission (AEC). The pertinent passage in that letter, which Management of the HSST Program, was signed by William Manly, a former with Joel Witt as Program Director, was Metals and Ceramics Division member, established in the Reactor Division was as follows: ((. . .To reduce further the (now Engineering Technology Division) already small probability of, pressure with the Metals and Ceramics Division vessel failure, the committee suggests responsible for metallurgical studies, that the industry and the USAEC give laboratory mechanical property experi- still further attention to methods and ments, and irradiation effects. The details of stress analysis, to the devel- program was to be carried out in opment and implementation of im- close cooperation with the material proved methods of inspection during suppliers, pressure vessel fabricators, fabrication and vessel service life, and and design segments of the nuclear

reactor project years power industry. The HSST Program tory weighed as much as 2080 kg Staff at inception included Domenic (4580 lb). Canonico, and Ray Berggren, in the 95 materials characterization task. Results from these studies showed that, even in such thick sections, these The first project of the program was the steels exhibit a ductile-brittle transition preparation of a white paper, well below the operating temperature of ORNL-NSIC-2 1, on Technology of Steel reactor pressure vessels, so that vessel Pressure Vessels For Water-Cooled safety was assured through ductile Nuclear Reactors, A Review of Current material behav&r, They also provided Practice in Design, Analysis, Materials, the basis for the development of Appen- Fabrication, Inspection, and Test, dix G, Section III of the ASME Boiler which was published in December and Pressure Vessel Code. __ 1967 and served as a state-of-the-art report on the technology of steel reactor By 1974, it became apparent that the pressure vessels. HSST Program was going to be exl tended beyond its planned 6-year life. . From inception of the program until To provide for a more efficient and 1974 the M&C activities concentrated , focused., response to program needs, the on procurement and characterizati,o.n.,of Steel Tech~nology Group (now the Frac- large plates prototypic of nuclear reac- ture Mechanics Group) was organized tor vessels under design [a press re- within the Engineering Materials Sec- lease of October 10, 1966, announced tion on March 8, 1974, led by production of THE WORLD’S HEAVI- Canonico. Until that tim,e, all the frac- EST PLATE, more than 45,000 kg ture toughness testing for the HSST (100,000 lb) by Lukens Steel Co. for Program was subcontracted to outside ORNL], fabrication and characterization companies. With added personnel the of prototypic submerged-arc group procured equipment and devel- weldments, development of fracture oped in-house capabilities for fracture mechanics experimental techniques toughness testing and in December * and data, irradiation effects, and inter- 1979 began to develop capabilities in mediate vessel tests. crack-arrest toughness testing.

From 1967 to 1974, the plates and One of the hallmarks of the H,SST fabricated weldments were used to Progam was the experimental and extensively characterize mechanical analytical studies using intermediate- properties and fracture mechanics sized. pressure vessels designed and behavior, including variability through fabricated according to ASME Code the thickness and throughout the rules from prototypic nuclear vessel plates. Some of the HSST specimens materials. These vessels were fabri- tested by the Naval Research Labora- cated with 1 m (39 in.) outer diameter,

reactor project years 0.15 m (6 in.) thick, by 1.37 m (54 in.) the elevated tensile strength and de- long cylindrical test sections. From graded fracture toughness of irradia- 96 1972 to 1982, twelve tests were per- tion-embrittled steels. Extensive frac- formed on nine intermediate vessels lure toughness experiments character- with varying flaw sizes. ized the fracture behavior of the vessel materials and provided the basis for This series of experiments provided experiment design. definitive confirmation of the large margin of safety inherent in Code These experiments revealed that frac- designed and fabricated nuclear vessels ture toughness tests with small speci- in the as-fabricated condition. The mens in the transition temperature group provided considerable input to region exhibit substantially larger both the material property data base scatter than had been realized, and the

required for experimental design and use of statistical analyses was subse- l the posttest evaluations, while Robert quently investigated. Iskander (C&TD) McClung and his group developed developed a suite of codes that became nondestructive evaluation techniques. known as the OCA (overcooling acci- dent) Code used for analyses of vessels Shafik Iskander of the Computing and subjected to thermal shock and, later, Telecommunications Division (now of pressurized thermal shock. the Metals and Ceramics Division) developed the first major fracture Extensive posttest fractographic exami- mechanics computer code for analyses nations correlated the observations of the vessel tests. Another major from the instrumented experiment with aspect of importance for all the large various fracture events; Randy Nanstad structural experiments was the devel- showed that the arrest of a cleavage opment of an electron-beam hydrogen- crack is not preceded by a mode con- induced cracking technique for produc- version to ductile tearing. ing sharp flaws in specimens. Important results from these experi- From 1975 to 1983, a number of land- ments included the observations that mark vessel experiments were con- short, shallow surface flaws could be ducted to investigate the behavior of made to grow long and deep by a series vessels, with varying flaw sizes, when of multiple initiation-arrest events, subjected to a “thermal shock” result- which could be predicted from the ing from injection of cold water by the fracture toughness and crack-arrest emergency core cooling system during a data obtained with small laboratory loss-of-coolant accident. specimens.

Canonico and coworkers developed a From 1984 to 1987, two technically heat treatment schedule to simulate challenging and significant pressurized

reactor project years thermal-shock (PTS) experiments were with weld overlay stainless steel clad- conducted with flawed intermediate ding were tested in two experimental sized vessels to investigate the com- phases from 1984 to 1989. The series, 97 bined effects of thermal and pressure of experiments showed that, with the loadings, and wide plate crack-arrest materials used, the cladding had a experiments were conducted by the limited capacity to arrest a running HSST Program at the National Bureau flaw on the surface. Another important of Standards. Nanstad and coworkers aspect was the demonstration of a conducted fracture toughness and ductile-brittle transition that results in crack-arrest toughness characterization the cladding from brittle fracture of the and heat treatment studies similarly to small volume fraction of delta-ferrite as the thermal shock experiments. the temperature decreases.

In this case, however, Nanstad and The task involving the largest contribu- others incorporated the single-specimen tion from the Metals and Ceramics compliance and dc-potential drop tech- Division is that of irradiation effects; niques for computer control to produce the program has irradiated a larger J-integral resistance (J-R) curves. Bill volume of material than any known Corwin and coworkers incorporated the program in the world. Because of the use of duplex specimens to increase the degrading effects of neutron irradiation, temperature range over which small the overcooling accidents are signifi- specimens could provide crack-arrest cant to vessel integrity. data and developed techniques for conducting crack-arrest tests with From 1968 to 1972, a series of experi- precracked and warm-prestressed ments was conducted under subcon- specimens to control initiation condi- tract. They emphasized the need for tions at low temperatures. irradiation of large fracture mechanics specimens. Berggren and Walt The PTS and wide-plate experiments Stelzman found that the largest practi- demonstrated that reactor pressure cal specimen for such experiments was vessel steels, even those with very low a compact specimen of 10 1.6 mm tearing resistance, can exhibit arrest (4 in.) thickness, which weighs about toughness values higher than the limit 45 kg (100 lb). suggested in the ASME Code, and the arrest values obtained from the small From 1972 to the present, seven series laboratory specimens compared very of experiments have been completed well with those from the large tests. and three are currently under way. In the course of those irradiations, 34 of To examine the role of stainless steel the largest specimens have been cladding, if any, in the behavior of irradiated and remotely tested. These surface flaws in reactor vessels, plates experiments have produced valuable

reactor project years information regarding the effects of Series. In 1990, the irradiation task irradiation on the fracture toughness was split from the HSST Program and 98 and crack-arrest toughness of plates, organized as the Heavy-Section Steel welds, and stainless steel cladding, Irradiation (HSSI) Program, with with significance to the integrity Corwin as program manager. analyses of reactor vessels. Other examples of research not directly The early experiments and Series 1 connected with the large structural test demonstrated that crack initiation projects are (1) investigations of size fracture toughness can attain high effects in linear-elastic and elastic- values under dynamic loading, even plastic fracture mechanics with accom- after irradiation. The Second and Third panying statistical analyses for even- Series showed that irradiation can tual development of an ASTM standard markedly reduce resistance to ductile on fracture toughness testing in the tearing, even for welds with transition temperature region; (2) the unirradiated low tearing resistance. effects of thermal aging on the base metals and stainless steel cladding A plate and four current-practice welds used for reactor vessels; (3) irradiation tested in the Fourth Series validated effects on vessel support materials; and the use of current welding practices as (4) evaluation of the Yankee Reactor well as low copper and nickel contents vessel embrittlement. to significantly reduce the irradiated fracture toughness degradation. The In summary, the HSST and HSSI pro- Fifth Series irradiated and tested 110 grams comprise three broad areas of specimens (including 16 of the largest investigation involving materials, analy- specimens) of two high-copper welds sis, and experimental validation, with and showed that the irradiation-in- efforts closely coordinated to result in a duced fracture toughness shift can be unique program in solid mechanics greater than that from Charpy impact research and development concerned specimens and that the fracture tough- with reactor pressure vessel safety. The ness curve may change shape. programs have earned broad support from industry and government and Crack-arrest tests of the same welds in have been given the opportunity to the Sixth Series more than doubled the produce results vital to the safe opera- world’s database for irradiated crack- tion of nuclear power systems. The arrest tests. The Seventh Series demon- people of the Metals and Ceramics strated that the fracture toughness of Division have played a significant role stainless steel weld overlay cladding is in that effort over its more than 30-year degraded by irradiation; and currently history. a high-copper, low-upper-shelf weld is being tested and irradiated in the Tenth

reactor project years Iiquid-:mGtaI fast breeder reactor

In the late 1960s and early 197Os, the most importantly for the Metals and U.S. Atomic Energy Commission (AEC) Ceramics (M&C) Division, fuels and and Energy Research and Development materials. 99 Administration (ERDA) made the devel- opment of a Liquid Metal Fast Breeder When Oak Ridge, Tennessee, was Reactor (LMFBR) a focal point for reso- selected as the site for the CRBR, it lution of the emerging energy crisis became apparent that significant inter- associated with continuing U.S. indus- actions among the staff of the indus- trial growth. trial contractors and M&C Division principal investigators would be needed Light water reactors (LWRs) of the to optimize technology transfer. At pressurized and boiling water varieties times, as many as 30 person-years per were being ordered by U.S. utilities in year of Division effort were involved. preference to fossil-fired plants, and it However, by the late 1970s earlier was projected that as many as seven- government predictions of a “uranium teen lOO-MW(e) nuclear plants would gap” evaporated, and the urgency of be brought on line each year, totaling breeding plutonium also vanished, about 300 by the year 2000. At this resulting in the cancellation of the rate, rapid depletion of the U.S. (and CRBR project in 1983. the world’s) 235U supply was inevitable, even with recycling of 23gPu from the Since LMFBRs would operate under LWR plants. conditions where creep and thermal transient loading effects could be sig- Although the United States had pio- nificant, the Mechanical Properties neered sodium-cooled reactor technol- Group, directed by Chuck Brinkman, ogy, i.e., the 20-MW(e) EBR-II in 1963, was responsible for satisfying the data the rest of the industrial world had requirements for implementing ad- moved ahead to the demonstration vances in high-temperature inelastic plant stage. In 1976, the Clinch River design methods. Thus, servo-controlled Breeder Reactor Project (CRBRP) was testing machines and high-resolution finally authorized with Westinghouse, extensometry were developed to gain General Electric, and Rockwell Interna- more information on the essential tional corporations playing key roles. behavior of high-temperature alloys.

Oak Ridge National Laboratory was High-temperature pressure vessel and selected as a very important partner on structural materials, that received the the LMFBR team because of special most attention incllded~ types 304 and talents in nuclear safety, physics, 3 16 stainless steel, 2- l/4 Cr- 1 MO instrumentation and controls, high- steel, alloy SOOH, alloy 718, and modi- temperature structural design, and, fied 9 Cr-1 MO (T-9 I) steel. As a result

reactor project years of data developed on cyclic hardening, as available from Babcock & Wilcox primary creep, complex creep-plasticity (B&W) Tubular Products Group, 100 interactions, creep-rupture, high- and Nippon Kokan K.K., Sumitomo Metals low-cycle fatigue, creep-fatigue, and Industries in Japan, and Valourec in crack growth, the American Society of France. Mechanical Engineers (ASME) Boiler ASME Code cases have been approved, and Pressure Vessel Code cases were approved allowing use of types 304 and and Rockwell International Corporation 3 16 stainless steels, 2- l/4, Cr- 1Mo has requested an inquiry for revisions steel, and alloy 800H in highitempera- to other cases Sect. III to permit ture nuclear applications for the first nuclear applications of modified 9 Cr - 1 time. MO steel. After ten years of develop- ment, modified 9 Cr-1 MO steel is a One of the major accomplishments of commercially available material that the LMFBR Program was the develop- may be specified for use in an ad- ment of an improved steel for steam vanced LMR and is being used world- generator and other applications. In wide in fossil plants and other applica- 1974, the Department of Energy (DOE) tions, an outstanding example of tech- authorized a task force to evaluate the nology transfer to the credit of DOE deficiencies in types 304 and 3 16 stain- and M&C Division staff. less steels for liquid metal reactor (LMR) applications. Nondestructive testing (NDT) was es- sential to ensure the integrity of the This group selected candidate alloys separation boundaries between water with the potential for improved perfor- and sodium in the steam generator for mance and developed a plan to acquire the LMFBR, and radiography was one the data base needed for use of each of the NDT techniques required for alloy in a future LMR economy in the evaluation of the tube-to-tubesheet late 1980s. The task force recom- weld joints. The basic approach devel- mended that an improved ferritic steel oped by Bill Foster of the NDT Group be developed by modification of a 9 Cr- involved placement of a very small 1 MO steel composition. gamma-ray source on the central axis of the tube in the plane of the weld Vinod Sikka was designated task joint, surrounding the joint with radio- leader, and criteria that the alloy would graphic film, and making a 360’ pan- have to meet were established. Subse- oramic exposure of the joint on a single quently, American Society for Testing radiograph. and Materials (ASTM) specifications were established for most product Miniaturized wire- and hole-type forms, and the alloy is now advertised penetrameters were fabricated and

reactor project years used to assess image quality of the plant. Both the thickness and radiographs. Through cooperation with ferromagnetism made this inspection the Isotopes Division at ORNL, these very difficult with eddy currents. Caius IO/ initial studies led to the development of Dodd of the NDT Group determined techniques for fabrication. of-nearly that magnetic saturation was needed to spherical sources of iridium, ytterbium, overcome these factors. He found that a and thulium with diameters as small as power of about 0.5 MW furnished 0.01 in. (0.25 mm). enough field to saturate the tube.

These fabrication techniques were However, that much power caused subsequently transferred to private overheating, and the probe could not be industry, and the studies led to the pulled through the tube with the mag- development of a microfocus rod-anode netic field energized. The solution was x-ray unit at Technisch Physische to use a pulsed field that saturated the Dienst in Delft, The Netherlands. tube for microseconds before being turned back off. This technique gave Ultimately, the high-sensitivity, high- about the same inspection sensitivity resolution radiographic technique using for ferromagnetic tubing as the mul- the rod-anode x-ray unit was selected tiple frequency test for the austenitic and successfully used to test the tube- steam generator tubing. to-tubesheet welds for porosity, cracks, and other minute flaws. To date, no Later designs of the pulsed system leaks have been found in the tube-to- reduced the saturation power to about tubesheet welds evaluated with this 200 kW and allowed faster inspection. boreside technique, even after many The technique has since been used to thousands of hours of operational inspect the steam generators of the testing. Yankee Rowe plant, where magnetite deposits on the inside of the tubing had The potential danger of a tube leak from previously hindered inspection at- steam to sodium was also recognized as tempts. an important reliability and safety factor in the LMFBR steam generator. A Other research and development ac- method of eddy-current inspection was complishments in support of the used for the pressurized-water reactor CRBRP and follow-on commercial (PWR) plants mainly for its high speed. plants included:

However, the tubes in the breeder 1. development of cladding and duct steam generators were made of a thick, alloys to achieve 150 MWd/kg ferromagnetic material rather than the burnup and a 15-year doubling austenitic material used in a PWR time.

reactor project years 2. evaluation of europium sesquioxide 6. determination of the weldability of (Eu203) as an advanced absorber and development of optimized 102 material, including fast-neutron welding procedures for structural irradiations in the EBR-I. materials for primary, secondary, and steam generator circuits, 3. novel fabrication techniques for including transition joints. high-temperature boron nitride (BN) electrical insulators for simulated 7. working with the Japanese to fur- fuel element behavior studies. ther develop mechanical properties and constitutive equations for equipment development for convey- 4. modified 9 Cr- 1 MO steel (1989- ing, dispensing, and blending to 1992). achieve high-density “sphere-pat” loading. 8. working with the Japanese to de- velop mechanical properties data on 5. evaluation of the compatibility of an improved grade of stainless steel candidate steam generator materials (316 FR) in support of fast breeder with contaminated superheated reactor development in Japan steam under a high heat flux. (1993-2000).

reactor project years 1975-l 996 structure and properties of surfaces

Bob Clausing began the study of the Auger electron spectroscopy and other 104 structure and composition of surfaces surface analytical techniques have and grain boundaries in 1969 to find remained the key technologies in this the cause of embrittlement of the laboratory ever since. Dewey Easton, nickel-based Hastelloy N (previously Lee Heatherly, Scott Halstead, and Dot described as INOR- in the ANP sec- Emerson soon joined the surface analy- tion) used as the container for the sis laboratory to build customized Molten Salt Reactor. A home-built equipment for work in the Molten Salt Auger electron spectrometer system Reactor and other projects, including showed unambiguously that tellurium the studies of the friction and outgas- in the grain boundaries caused the sing of fuel elements for the nuclear embrittlement. rocket (for NASA), the embrittlement of grain boundaries in metals by neutron irradiation, and the plasma-material

Fig. 12. Ray Padgett at the console of the Physical Electronics ModeZ 590 scanning Auger microprobe, which has been modified to permit tensile, bending, or impact f+arcture of irradiated materials at cryogenic or elevated temperatures. The grain boundaries exposed by the fracture can be analyzed to study radiation-induced or other segregation.

diversification and the high-technology years Fig. 13. Lee Heatherly and Diamonds Are Forever. He is checking on the growth of a IO5 diamond film by hot-filament- assisted chemical vapor deposition. The insert shows individual diamond crystals and a polycrystalline film formed by their coalescence.

interaction studies which continued for ductility. This work continues under many years in support of fusion energy. Easo George and graduate students.

The plasma-material interaction” stu,d-, In 1988, a seed,.; money proposal, and ies included “field” work ,and, Auger some support from the U.S. Army. electron spectroscopy (Fig. 12) using provided the beginning for a series of ORNL designed and built equipment on studies to link the growth and struc- fusion energy experiments not only in ture to the properties of diamond. This Oak Ridge but also in San Diego, Rus- was an outgrowth of the plasma-mate- sia, Germany, and England. Cal White rials interaction studies. Several hot- and Ray Padgett joined the group to filament-assisted chemical deposition study segregation to metal and inter- chambers are now in use to grow dia- metallic grain boundaries. Auger elec- mond films (Fig. 13) and freestanding tron spectroscopy established that sheet, while optical and electron mi- thorium in grain boundaries of iridium croscopy as well as surface techniques improves its high-temperature impact are used to study the structure and ductility. Auger electron spectroscopy composition of diamond surfaces and also showed how boron segregation to diamond-substrate interfaces. Current grain boundaries in Ni,Al improved its studies include exploring the growth of diamond single-crystal films on nondiamond substrates,

diversification and the high-technology years fossil energy program

The Atomic Energy Commission (AEC) On his initial visits to fluidized-bed 106 was replaced by the Energy Research combustion (FBC) plants (e.g., the and Development Administration Rivesville FBC plant) and coal liquefac- (ERDA) in 1975, and the Office of Coal tion pilot plants (e.g., those at Fort Research (OCR) was moved from the Lewis, Washington, and Wilsonville, Bureau of Mines to ERDA. Recognizing Alabama), Roy King encountered a the opportunity for coal-related re- great deal of skepticism. How could search for OCR, ORNL initiated “The this metallurgist from a nuclear re- Coal Program ,= under the guidance of search center possibly help them with Jere Nichols of the Chemical Technol- their problems in running their coal ogy Division. Since many of the tech- combustion or coal liquefaction plant? nologies for burning coal or for convert- Roy recounts some of his early experi- ing it to liquid or gaseous fuels required ences: materials that could be used at high temperature and/or high pressure in “During the plant tour I would often see very erosive or corrosive environments, a scrap heap with several failed compo- materials research and development nents on it. When I asked about these (R&D) was needed to support OCR’s components, I would be told, ‘Oh, that’s coal technology programs. just a pipe (or pump, or valve, or ves- sel) that failed last week. We replaced it Bill Martin, then Head of the Engineer- and started up the plant again.’ I would ing Materials Section, along with ask if I could take the failed component Gerald Slaughter and Roy King, were back to the Laboratory to see if we soon on the road, getting to know the could determine the cause of failure. people at OCR Headquarters and at the After we had successfully identified the Energy Research Centers at Pittsburgh cause of failure and had made recom- (PERC) and Morgantown (MERC): mendations to prevent recurrence on a Roy King began a project to provide few occasions, the people at the pilot failure analyses for components from plants began calling us when they had coal combustion and coal conversion a failure.” pilot plants. These early efforts by King, .Godfrey, Domenic Canonico and coworkers of and Canonico were the genesis of the the Steel Technology Group (now Frac- Fossil Energy Materials Program in the ture Mechanics) assessed R&D needs Metals and Ceramics Division. for coal conversion pressure vessels. Gordon Godfrey went on assignment to By 1978 ERDA had become the Depart- PERC to learn about OCR activities and ment of Energy (DOE), and OCR had to provide an interface between PERC become DOE’s Office of Fossil Energy. and ORNL. Following the runup in energy prices

diversifkation.and the high-technology years resulting from disruptions in the Mid- the meantime, the failure analyses task east oil supply in 1973 and 1976, had expanded to include in situ materi- 107 President Jimmy Carter declared “the als testing at several liquefaction moral equivalent of war.” He set a plants, and James Keiser and .Vivian national goal to double the use of coal Baylor were making regular trips to and to provide a significant portion of Fort Lewis, Washington, and the nation’s liquid fuel needs by con- Wilsonville, Alabama. They brought verting coal to gasoline and fuel oil. considerable credit to the Laboratory when they recognized that fractionation Federal funding for coal R&D was column corrosion was common to all expanding, and DOE Fossil Energy was the pilot plants and that it was related initiating several demonstration to the chlorine content of the coal. projects with industry on coal liquefac- tion, coal gasification, and fluidized-bed With the insight derived from the re- combustion. In that climate in 1978 sults of in situ testing at the pilot DOE asked ORNL to devote significant plants, careful laboratory experiments, resources to fossil energy research; in and some help from Rod Judkins’ essence, to become a “lead lab” for chemical engineering background, a fossil energy. good understanding of this corrosion process was developed and methods of The task of building a significant fossil preventing it identified. energy research program at ORNL was given to L. E. (Gene) McNeese, who by About 1980 DOE-OR was given respon- then was Director of the Laboratory’s sibility for the H-COAL coal liquefaction Fossil Energy Program. pilot plant being built at Ashland Oil Co.% refinery in Catlettsburg, Ken- One of the first national programs for tucky. A team of Metals and Ceramics which ORNL was asked to take the-lead Division staff members including role was the Fossil Energy Materials James Keiser, Rod Judkins, Arnold Program, managed by Ron Bradley. The Olsen, Jack DeVan, and Ron Bradley task during the first year was to trans- reviewed the materials of construction fer research projects from Headquar- and worked with the industrial partici- ters to DOE-OR/ORNL and to begin pants in the project (Ashland Oil and research to address the materials ,. j Amoco) to develop a materials test plan. needs of the coal liquefaction, coal gasification, and fluidized-,bed. combus-. Bob Swindeman.” I. ^ >-, a. zc ~*I-“.+ \ led_,,__._ a ‘project to per- tion pilot plants. form a cyclic stress analysis on the H- COAL reactor pressure vessel, and Rod Judkins and Paul Carlson and through this effort became the Fossil,. later Nancy Cole assisted in the man- Energy Materials Program’s resident agement of this National program. In expert on the requirements for coal

diversification an@ the high-technology years conversion pressure vessel materials. Fossil Energy Materials Program shifted 108 By the time the H-COAL plant was to long range research to provide new started up, ORNL had established an materials and processes for future coal excellent working relationship with the conversion or coal combustion pro- engineering and operations staff at the cesses. plant. On one occasion, an H*-COAL executive attending a meeting at DOE- Phil Maziasz and Bob Swindeman used OR received word that a component the insight gained during several years failure had shut down the plant. He of microstructural analysis of alloys on requested assistance from ORNL in the Fusion Materials Program and identifying the cause of the failure, and knowledge of the requirements of alloys within hours Bob Gray was on Ashland for fossil energy applications to develop Oil Company’s corporate jet, headed for advanced austenitics for use in coal- Catlettsburg, Kentucky. fired steam generators.

Also in the early ‘8Os, ORNL and TVA C. T. Liu began research on nickel-iron began a cooperative effort on fluidized- aluminide to determine how much iron bed combustion technology, and Roy could be substituted for nickel in duc- Cooper became the M&C Division’s tile Ni3Al. This work contributed sig- personal envoy to Chattanooga. nificantly to the development of the nickel aluminide alloys later licensed This led to considerable research in the by ORNL to industry and led to the Division by Pete Ficalora on the effect later development of iron aluminides by of a pulsating oxidizing-reducing atmo- Claudette McKamey, C. T. Liu, and sphere on corrosion processes, by Jim Vinod Sikka. Keiser on erosion mechanisms of solid particles impacting the surface of an Jack Lackey and later Ted Besmann alloy, and by Jack DeVan on the effect and David Stinton conducted work on of calcium sulfate scales on the corro- the fabrication of continuous fiber sion of fluidized-bed combustor in-bed reinforced ceramic composites by heat exchanger tubes. chemical vapor infiltration (CVI) , which eventually established ORNL as a world As time passed and the “energy crisis,” leader in forced-flow CVI. This led to eased, the long gasoline lines of the considerable other research on CVI mid-seventies were forgotten and the funded by the Air Force and by the need to develop coal liquefaction and Conservation Advanced Industrial coal gasification technologies dimin- Concepts Materials (nee ECUT, Energy ished on the national agenda. President Conversion and Utilization Technolo- Reagan closed down the large pilot gies) and Continuous Fiber Ceramic plants and canceled plans for the large Composites Programs. demonstration plants. Activities on the . diversification and the high-technology years svrichhotron radiatiob b,eamline

The Metals and Ceramics Division is a tense synchrotron sources with lo3 to key player in the development of syn- lo6 times the brightness of conven- chrotron radiation as a probe for mate- tional x-ray sources have brought new I09 rials science. In the middle 1970s opportunities to study defects in bulk members of the Metals and Ceramics materials. Division’s X-Ray Group began using an early synchrotron x-ray source at The Department of Energy funded the Stanford University. Based on their construction of a synchrotron radiation experience, they developed an x-ray facility (National Synchrotron Light fluorescence microprobe in 1976 with Source, NSLS) at Brookhaven National unprecedented sensitivity to test the Laboratory on Long Island, New York, reported existence of superheavy ele- for completion in 1984. The X-Ray ments. The microprobe was the first Diffraction Group of the Metals and application of crystal focusing optics to Ceramics Division took the-lead vyit.h .__X- __ hard x rays at a synchrotron. It conclu- Ray Groups of the Solid State and sively demonstrated that the proposed Chemistry Divisions to fund (-$900X) superheavy elements did not exist in and to construct an x-ray diffraction the samples at the concentra- tions reported.

Though x-ray diffraction has been the major tool for solv- ing the long-range and peri- odic arrangements of atoms in matter, intense electron microprobes and microscopes partly replaced the weak x- ray sources for general pur- pose sample characterization beginning in the late 1960s. Both the crystal structure and the disruptions from this Fig. 14. Members of the construction team tha# long-range periodic@ are built aA x-ray diffraction facility.at the newly useful to the understanding proposed National Synchrotron Li&ht S&ce are of changes in materials prop- shown in 1981 with th&-pecent purchase of a 4- erties. circle goniometer to orient samples in the x-ray beam. Softwclre for computer control of motor Since the diffraction effects drives was an in$erdivisio?@ effort. From left are Cullie Sparks (M&C), David McMillan (I&C], Tony from these disruptions of the Habenschuss (ORAU Rese(zrch Associate), Gene Ice, perfect order are weak, in- and Harry Yakel (M&C).

diversification and the high-technology years _h beamline at this new synchrotron amazed when the beamline suddenly facility. Construction began in earnest appeared intact on the NSLS floor. in 198 1 with the team shown in Fig. 14 gathered around our first large pur- This synchrotron beamline has resulted chase (a crystal diffractometer used to in many collaborative research projects orient the sample in the synchrotron x- within the Metals and Ceramics Divi- ray beam). New x-ray optics were in- sion, with other ORNL scientists, and vented and patented to focus synchro- with hundreds of scientists from doz- tron radiation. This invention in x-ray ens of universities, industries, and optics won an IR 100 award and has other government laboratories. Collabo- become the standard for focusing hard ration is open to scientists in research x rays from synchrotron sources. The areas of importance to DOE programs. facility was assembled on the ground This high intensity x-ray facility has floor of Building 4508 of the Metals and helped uncover new information about Ceramics Division. In 1984, the equip- the structure of metal alloys, interme- ment was loaded on a large van, as tallies, interfaces, thin films, ceramic shown in Fig. 15, and moved to the surfaces, quasicrystals, heavy fermion NSLS. Workers at Brookhaven were systems, and superconductors, among others. This new information is leading to a better under- x standing of the pw&:. ,-” relationship be- .** tween the structure and properties of materials. A newer facility is under construction for the Advanced Photon Source at Argonne National Labora- tory, which will provide a thou- sandfold gain in brightness when completed in 1996.

Ng. 15. After completion of the x-ray beamline con- struction at ORNL, riggers operate a forklifl to load the equipment onto a van for transportation to the National Synchrotron Light Source on Long Island. diversification and the high-technology years shared+,,research equipment program: collaborative research at orn,l

Since its inception in 1979, the Shared efits derived from, SHI-IRE providing Research Equipment (SHaRE) Program access for outside investigators to the Ill at Oak Ridge National Laboratory has world class. AEM/APFIM/MPM facilities permitted collaborative research., at ORNL” are“, _a/*, manyfold. .^_lA Few universities projects by the staff of the Metals and, I.. or industriesj I.ip^,. ,e-‘..t:i. &>m.A>&w.VYcan afford.e”-,- .: b ~~,ri_., state-of-the-art_i, ,.a>. \*a\f~$,” .r>. d. Ceramics (M&C) Division and s,cientists . facilities in,“all ,relevant ..,~Vd .S” , >U.,**,, areas.‘, i, _ :i?rr..-4,. The __ from universities, industries, and other national laboratories.“_‘,_I ~. . provide an im- national laboratories. These projects mens.e resource of such facilities. take advantage of the facilities within The-current facilities covered under the M&C Division that often.” /~-A, I . define..*/ ..,^, _,. ,1 “_ ., ” SHaRGi _.> I _.a;. incitiae fif6;;c~~~~wg;~,*zti *ApFIM state-of-the-art and are, a major na- tional resource. Thus, SHaRE enables (Fig. 16), and two MPMs. Currently research projects that are valuable to under development are a high-tempera- both outside investigators and ORNL ture MPM and two APFIMs, including scientists. the mapping atom probe (MAP), all of which will be available under SHaR,E The SHaRE program is designated a wh.en fully functional and user ready. User Facility by the U.S. Department of Both an advanced_2.Oe:.kV field) emis-T.. .- .**a- Energy (DOE). However, unlike many sion gun AEM and an analytical scan- other User Facilities, the SHaRE pro- ning electron microscope was added gram requires that projects are collabo- during CY 1994. The M&C Division’s rative. The program has been funded Microscopy and Microanalytical Sci- by the DOE, Office of Basic Energy ences (M&MS) Group is responsible for Sciences (BES), Division of Materials maintaining and developing the AEM, Sciences. In the past 18 years, SHaRE- APFIM, and MPM facilities and provides related research has resulted in over a core of expertise and talents upon 280 publications, a similar number of which the SHaRE projects draw. In presentations at national and interna- addition, other M&C Division staff tional meetings, and 53 completed M.S. collaborate on such projects. These and Ph.D. theses. scientists have demonstrated expertise in the application of AEM, APFIM, and Whereas access to many of the re- MPM and are nationally and interna- search facilities within the M&C Divi- tionally recognized in their fields. The sion is possible to SHaRE participants, primary thrust area for the M&C Divi- the strongest interest has been in the sion (and therefore most SHaRE transmission electron microscopy projects) is structural materials and the (TEM), analytical electron microscopy correlation of processing, structure, (AEM), atom probe field ion microscopy and properties for a wide range of (APFIM), and mechanical properties metallic, ceramic, and composite mate- microprobe (MPM) facilities. The ben- rials. Additional SHaRE projects have

diversification and the high-technology years 112

Fig. 16. A number of SHaRE projects have utilised the atom probe field ion microscope (XPFZM) for high spatial resolution imaging and microanaLysis that can approach near atomic level. The APFI.M pro- vides the combined capcrbilities of a field ion microscope, a time-of- fright atom probe, and an imaging atom probe.

dealt with the application of micro- structured materials, and embrittle- scopic techniques to magnetic materi- ment of metals. A conscious decision als , catalysts, and semiconducting has focussed the efforts of the M&MS device materials. Recent areas of re- Group staff in its strength areas and search include high-Tc superconduc- has defined and obtained state-of-the- tors, surface-modified polymers, nano- art facilities for its studies.

diversification and the high-technology years The electron beam welder (Fig. 17) was gram, and weldability evaluations for obtained in 1984 by the Materials new alloys. II3 Joining Group to support both the New applications are continually being welding research activities and special- found for this machine, which moves ized joining needs of several programs at ORNL and other laboratpries. Appli- the components by computerized nu- merical control under a high-intensity cations for this equipment have in- beam of focused electrons. By utilizing eluded fabrication of electrodes for the ,. _ _, .. ,, I/ ^ - ,, _. production of the wide range of electron beam power available iridium alloy, (15kWmaxi- specimen mum) and beam joining for manipulation large heavy- features, one section steel can weld mate- fracture me- rials ranging chanics test- from thin metal- ing, refractory lic foils to 80- alloy test mm-thick plate. coupons and Defocused and component magnetically joining for deflected beams space nuclear can also be power project, used for mate- joining of rial heat treat- precision ment, surface components treatments, and for the fusion brazing. energy pro-

Fig. 17. Leybold-Heraeus Electron Beam Welder, shown here with J. D. Hudson, can make precision microweLds and high depth-to- width ratio deep penetration weLds in a range of materials.

diversification and the high-technology years the high temperature materials laboratory

On April 18, 1989, the Coors Corpora- HTML, was presented to the Basic I14 tion announced its plan to build a new, Energy Sciences (BES) staff of the advanced high-temperature ceramics Department of Energy who authorized production and research facility in Oak a formal conceptual design study. John Ridge, Tennessee. This corporate deci- Cathcart of the M&C Division became sion to bring a new, high-technology involved in moving the project forward industry to Oak Ridge is but one ex- and remained so until construction was ample, among many, of the very favor- completed. able response of the industrial and academic research communities to the Almost everyone seemed to think that Metals and Ceramics (M&C) Division’s the concept of an HTML was a wonder- new High Temperature Materials Labo- ful idea, hopes were high for quick ratory (HTML). congressional approval and an actual start on construction. No such luck! As The HTML is a research facility that not Zucker likes to say, “the gestation time only contains an integrated staff de- for a major construction project is 10 voted to research in the critically im- years,” and in 1979, the project was portant new field of high-temperature ahead of that schedule. Not until the materials but also offers to the staff third Schedule 44, in September of and outside users access to the collec- 1982, at the very end of the fiscal year, tion of advanced, modern research appropriation of $1 million was accom- equipment needed to characterize, on plished. Success was triggered by two an atomic scale, the structure of new events: a director of the HTML, Victor materials. In addition, testing facilities Tennery, was appointed, and in Wash- are available to measure the physical ington, sponsorship of the project was and mechanical properties of newly switched from BES to the Conservation developed materials. and Renewable Energy area of DOE. A. Chesnes, the director of the Heat En- The idea of a special laboratory devoted gine Propulsion Division, assumed the to the study and development of high- responsibility for presenting the case to temperature materials originated in Congress. He arranged the million discussions among and between the dollars and enough additional in subse- research staffs of the M&C and the quent years to make a total of $19.1 Solid State Divisions in the early seven- million for the entire project. ties. The initial draft of a proposal to construct the HTML was prepared in That first million dollars set in motion August 1977 by Timothy Reiley of M&C the process the government uses in at the direction of Alex Zucker, ORNL selecting an architect for a construction Associate .Laboratory Director in charge project. The Pittsburgh architectural of the project. This version of the firm Deeter Richey Sipple (DRS) won

diversification and the high-technology years the design competition, and it along veiled in the HTML lobby acknowledg- with A M. Kinney, Inc., to whom DRS ing Al Chesnes’ contributions to the subcontracted the engineering design success of the project. work, began the actual design of the The HTML is a two-story glass-and- HTML. Within a year after architectural concrete structure containing 64,500 work started, we were able to obtain sq. ft of floor space consisting of 49 bids for the construction work. The low laboratories with office space for a staff bidder was Blame-Hays Construction of about 75. The final cost of the build- Corp., of Knoxville, Tennessee, whose ing itself was $9.8 million. Another bid was just over $9 million. $6.3 million was spent on the special Construction began in the snow on research equipment for the User Cen- January 20, 1985. It was too cold then ters, and $2.8 million represented the for a proper ground-breaking cer- cost of design and supervision. The emony, so an HTML Inauguration building accommodates two groups Celebration was held on May 27, 1985 involved in various aspects of research in front of the just completed architec- and development of high-temperature tural bent. Department of Energy ceramic materials. It also provides (DOE) Assistant Secretary for Conser- space for six User Centers, which vation, Donna Fitzpatrick, was the contain the sophisticated instntmenta- featured speaker. tion needed for the characterization of advanced high-temperature materials, Another two years was required to especially the new high-temperature complete construction. That was two ceramics that promise to be so impor- years full of problem solving - han- tant in the transportation industry. A dling the inevitable design changes, new ceramic manufacturability center coping with late deliveries by vendors, has been created recently and is also dealing with special requests from housed in the building. future occupants of the laboratory. The concept of the HTML as a user The leadership of John Murray, the center existed early in its evolution. architect, and our building contractor, When the HTML national user program caused the HTML to be finished within started, there were four user centers: budget and on schedule in time for the materials analysis, physical properties, formal dedication ceremony on April X-ray diffraction, and mechanical 17, 1987, almost exactly 10 years after properties. In 1992, due to industrial Tim Reiley’s draft proposal! Donna requests, two new centers were re- Fitzpatrick again led the speakers in quested and approved by the DOE. In predicting a useful future for the 1993, a new Ceramic Manufacturing HTML, and a special plaque was un- Center was started as a partnership

diversification and the high-technology years between Energy Conservation, Defense and ready for operation in Programs, and Energy Research that July 1987 - this facility resulted in focuses on new manufacturing pro- the U.S. ASTM standard method for cesses for advanced structural ceram- performing ceramic tensile strength ics. In 1994, a new Neutron Residual measurements. Stress Facility was approved for opera- 2. Development of specimen shape and tion; this facility provides industry the geometry requirements plus grip- capability, as users, to measure the ping systems for ceramic tensile stress field within complex components specimens which are now ASTM such as gears and turbine rotors. standards.

Over the years, the educational poten- 3. Development of the specimen sys- tial of the HTML became more and tem gripping systems for ceramic- more obvious, but there was no pro- ceramic (CFCC) composite tensile gram which could directly fund gradu- specimens which are in the process ate students or industrial researchers now of becoming ASTM standards. to come to the HTML for prolonged Development and implementation of periods to conduct their dissertation or 4. the statistical method for Weibull special research. Typical HTML user projects had lengths of about two or analysis of fracture strengths in ceramic materials in the United three weeks. There was a clear need for funds to support a researcher of a States. different type for a year of more. Solici- 5. Development of software for com- tations for both industrial and univer- puter control of diffraction spec- sity candidates in 199 1 resulted in two trometers which was particularly university candidates and three indus- user friendly. trial candidates being selected. This is 6. Creation of the first residual stress called the HTML Fellowship Program spectrometer in the U.S. based and has continued to grow. upon neutron diffraction. Several major research instrumentation 7. Implementation of ORNL’s first and research achievements have been laboratory complex using fully made during HTML operation largely digital imaging from electron optical due to needs identified with either instruments - this has resulted in users or prospective users. easier dissemination of data any- Some of these include: where in the world on the World Wide Web and has greatly reduced 1. Creation of the world’s largest ce- chemical effluent production com- ramic tensile testing facility with 12 mon to film developing. machines of a new class in place diversification and the high-technology years Y

8. Creation and demonstration of the Carlsmith, who was the Conservation mathematics and instrumental Program Manager at ORNL during this II7 requirements for successful electron entire time. ,In the latter years, Bill holography. Appleton, Associate Director for Physi- cal Sciences, was most supportive for 9. The elucidation of the microchemis- the program. try and microstructure of a @de variety of silicon nitride, silicon Vie Tennery retired on December 3 1, carbide, and fiber reinforced ce- 1994, and Arvid Pasto became the ramic matrix composites as a func- second Director of the HTML. tion of stress, temperature, and environmental exposure using the Since its completion, the HTML has ultrahigh resolution transmission gone a long way toward its initial prom- microscopes. This resulted in the ise. In 1988, it won High Honors in a first detailed understanding of nationwide laboratory design competi- cavitation processes in these struc- tion sponsored by Research and Devel- tural ceramics at high tempera- opment Magazine, and it is recognized tures as the architectural showpiece of the Oak Ridge National Laboratory. It lO.Elucidating for the first time the provides a staff of 75 with comfortable ultimate microstructure of a variety and attractive working areas and sur- of heterogeneous catalysts as a roundings. The research being done in function of their exposure in engine the high-temperature ceramics area combustion environments. attracts international attention, and In closing, five people must be men- the access by industrial and university tioned a last time, who were crucial to researchers to the research equipment the creation of the HTML. First, was in the User Centers is highly prized. Albert A. Chesnes, the DOE sponsor of Five and a half years after its comple- this laboratory. The remaining four tion, 175 user agreements have been include, Alex Zucker who provided signed, 79 with universities across the resources and encouragement. Felicia country and 96 with a variety of indus- Foust who was always ready to prepare trial concerns; in addition, there has documents, viewgraphs, or whatever been interaction with five other govern- was needed to stem the crisis of the ment laboratories. More than 26,000 moment; John Cathcart who based user days have been logged. The HTML upon his long experiences was helpful has, indeed, become a national re- in hundreds of ways during the cre- source for high-temperature materials ation and construction days; and Roger research.

diversification and the high-technology years multiple ion irradiation: metals, ceramics, and polymers

In the 1970s the Metals and Ceramics ences the radiation response of materi- 118 Division acquired a 5.5-MV “CN” als. Van de Graaffaccelerator (located in the 5500 building) for materials sci- In the 198Os, a third accelerator, a 2.5- ence, in particular, studies of radiation MV Van de Graaff was installed to effects. The accelerator, designed and permit simultaneous triple-ion irradia- built by High Voltage Engineering tions (Fig. 18). The third machine also Company, was first bought by ORNL in fulfilled needs for an intermediate size the 1950s for nuclear physics research. accelerator to be used for nuclear Later in the decade, a second accelera- reaction and Rutherford backscattering tor, a 0.4-MV Van de Graaff, was added analyses. The triple configuration to permit simultaneous dual-ion irra- allows a considerable generalization to diations. The smaller machine was be achieved in both radiation effects used primarily for helium injection and the larger ORNLJDWG 9OM-8574C machine for me- tallic self-ions of the specimen material.

The dual ion irradiation capa- bility turned out to be crucial in understanding neutron radiation effects in fission and fusion reactor materials. In a fission or fusion reactor environ- ment, displace- ment damage occurs while helium builds up

through (n,a) Fig. 18. Schematic of Triple Ion Irradiation Facility. reactions. Helium profoundly influ-

diversification and the high-technology years and ion beam treatment research. It of the three accelerator beam lines. The permits, for example, simultaneous target assembly has five individual I. 19 anion-cation-helium bombardments for target stations. The specimen tempera- studies on the fundamentals of dis- tures can be regulated between -196 placement damage and helium re- and 1000°C. The three ion beams enter sponse in ceramics, while it allows the chamber by separate ports approxi- independent control of defect behavior mately 15” apart. In addition to the induced by departures from stoichiom- main implantation chamber, the facility etry. This is particularly relevant for includes a film deposition chamber and studies of fusion reactor insulator an ion-scattering chamber (D). Auxil- materials, for example. Simultaneous iary equipment includes a computer- triple-beam capability is also a key to controlled goniometer, a residual gas powerful ion beam treatment research. analyzer, a 5-kV sputter-gun, and a 20- kV electron gun. Today the facility is The Triple Ion Irradiation Facility is used extensively for both basic radia- shown schematically in Fig. 18. The tion effects research and surface modi- primary implantation chamber (E in fication and analysis of metals, ceram- the figure) is located at the intersection ics, and polymers.

diversification and the high-technology years cdnservation materials program

Several separate entrepreneurial efforts istration under the White House.) The I20 that later evolved into conservation- FE0 began to look at some more long- related research and development range projects and authorized some of (R&D) were under way at ORNL. Roger the first experimental work on building Carlsmith’s involvement in conserva- insulation. The Laboratory got some tion began with the start of the Na- funding from Maxine Savitz who was tional Science Foundation (NSF) Envi- then head of the residential segment of ronmental Program in June 1970. the FEO.

Carlsmith’s effort on the NSF Program When the Energy Research and Devel- was associated with “Environmental opment Administration (ERDA) was Impacts of Electrical Energy Produc- created in 1975, the Laboratory lost its tion,” co-chaired with John H. Gibbons, NSF funding. However, with the advent who 20 years later became President of ERDA, energy conservation was Clinton’s science advisor and director given prominence in the federal govern- of the White House Office of Science ment, and the Laboratory started re- and Technology Policy. The charter was ceiving funding from ERDA for research to do a study of environmental impacts in this area. having to do with electricity. The first study identified energy conservation as The Metals and Ceramics Division’s the one strategy that would deal simul- involvement in the Energy Conserva- taneously with all of the environmental tion Program began with a phone call, impacts of energy production. For in early August 1975, from Bob Ander- about the first 2 years, funding came son of ERDA to Vie Tennery inquiring entirely from NSF, and the first 18 ’ about our capablilties for conducting months were devoted to analysis and research on high-temperature ceramic study with no experimental work. The and metallic materials, such as refrac- group did a number of technical as- tories and high-nickel alloys. Bob had sessments and some economic analy- just joined ERDA and was reporting to ses having to do with price elasticity of Doug Harvey, who was in the process of energy demand. defining and setting up a national energy conservation program including The whole energy situation changed in what are now the buildings and indus- the fall of 1973 with the Arab oil em- trial energy conservation programs. bargo. President Nixon established the Doug and Bob were then in the process Federal Energy Office (FEO) to deal of performing studies to identify indus- primarily with the impacts of the oil trial manufacturing sectors in which embargo, and the Laboratory began to the most energy-saving impacts might get some funding from this office (later be realized via improvements in indus- changed to the Federal Energy Admin- trial practices and/or the development

diversification and the high-technology years of new materials. At the end of August ture process flow streams, such as the Division was asked by Headquar- those in the primary metal (steel and ters to prepare our first energy conser- aluminum) industries and the ceramic vation research proposal involving an industries. This proposal resulted in a assessment of the technical status of second piece of work in which a materi- industrial thermal insulations. This als and equipment assessment was funded project was the beginning of the done for waste heat recovery devices, Energy Conservation Program in the where heat exchangers (typically called M&C Division. recuperators in industrial parlance) could be used. This work was funded in The industrial thermal insulation late spring of 1976 and was conducted project was completed in about six both in the Ceramic Technology and months, including a national workshop Thermophysical Properties Groups. held in Oak Ridge, and the results were This work helped M&C make many reported in ORNL/TM-5283 for which contacts in the industrial sector in the many hundreds of copies were printed areas of thermal insulations and waste and distributed to over 300 companies heat recovery systems, and at the time, that had provided information for the allowed the Division and ORNL to gain assessment project. The result of this the acceptance of industrial managers work was a new national awareness of and researchers as an organization the important energy conservation truly interested in their problems and potential for upgrading steam distribu- in helping them resolve important tion systems in all types of industrial energy conservation issues. plants, and the many unknowns asso- ciated with high-temperature ceramic The next opportunity that really offered insulation systems and waste heat the potential for substantial R&D came recovery systems. This was the first in late 1976 when many companies multi-divisional energy conservation were being denied access to their re- project involving the M&C and Energy quired natural gas supplies due to Divisions, and the work resulted in shortages from producers in the south- many new industrial contacts for the western United States. These firms Division in later years, as this assess- were then switching to residual fuel oil. ment was considered to be of high since highly refined fuel oil was too quality’by industrial people of the time. expensive--the impurities in these residual oils were quickly found to After completing the assessment on cause major corrosion problems in industrial thermal insulation, Tennery ceramic and metal processing furnaces. was asked to organize a proposal di- rected at questions associated with We were asked to organize and rapidly waste heat recovery from high-tempera- initiate an effort to determine the origin

diversification and the high-technology years of the corrosion and to recommend asked to manage various programs, one 122 possible solutions. This work included of which was Building Thermal Enve- George Wei and Gary Weber, plus a lope Systems and Materials (BTESM), large number of technical support staff, which Tom Kollie later took over and and resulted in a set of technical re- then Ken Wilkes. M&C eventually ports that were widely distributed to turned the BTESM work over to the industrial companies. The ERDA spon- Energy Division on the recommenda- sors required that the results be pub- tion of the Advisory Committee. lished as quickly as possible in official ORNL technical reports. The first two Around 1978, shortly after Tony reports, ORNL-5592 in 1976 and Schaffhauser took over as Energy ORNL-5909 in 1977, established that Conservation Program Manager, the the corrosive effects of these oil impuri- Division was directed to develop an ties were extensive and that analyzing energy audit program for houses and specimens from industrial furnaces apartments that the utilities companies was very difficult due to highly variable could offer to their residential custom- industrial operating practices, making ers. There needed to be a good techni- it extremely difficult to correlate spe- cal basis for doing this. cific oil impurities with refractory or A lot of this effort involved recommen- insulation failures. dations on insulating materials. M&C As the Energy Conservation and Utili- was asked to help primarily because of zation Technology Program was being Dave McElroy’s prior work on insula- initiated, the program in the Division tion standards. At that time, Dave had expanded to include building insulation been working with the American Soci- and other energy conservation systems ety for Testing and Materials (ASTM) such as walls and windows. The result and others on standard test methods. was that the predecessor of the Build- Dave had become involved in the stan- ings Conservation Program (a national dards work as an outgrowth of the effort) was started within the M&C industrial insulation program. Division. Dave McElroy and his group, It was next proposed that a major including Bob Williams and Peyton experimental combustion exposure Moore, became major participants in facility be constructed at ORNL in the program characterizing a large which thermal insulator and other number of building thermal insula- types of refractories could be exposed tions. This work has continued in some to residual oil combustion products in form to the present day. a controlled manner. The first results During this time also, Ted Lundy, a from this work showed that residual oil group leader in the M&C Division, was impurities, such as nickel and iron,

diversification and the high-technology years were very detrimental to the then newly ery. The first experiment was con- developed refractory fibrous ,insulations ducted during that summer and the being adopted rapidly by U.S. industry. first results showed the role of heavy 123 During 1978, five additional sets of metal fuel impurities in accelerating the experiments were performed. Material high-temperature corrosion of silicon exposures were conducted using multi- carbide and aluminum oxide ceramics hundred-hour combustion exposures in at temperature to 1300°C for exposures the Refractory Test Facility (RTF) in of hundreds of hours. This work be- addition to continued analyses of in- came the central focus of the Industrial dustrial refractory and insulation speci- Energy Conservation Program in the mens. Finally, a special assessment of M&C Division for the next several ceramic recuperator materials was years. conducted. This work resulted in con- siderable future work in the Solar The RTF was later modified and used Energy Program and later the Industrial for a four-year project sponsored by the Conservation Program. Fossil Energy Materials Program in which coals of various chemistries were In 1980, most of the R&D was focused fired in a special burner for exposing on experimental exposures in the RTF. structural ceramics to direct molten The results showed the modes of corro- slag impingement. sion and failure of a wide variety of ceramic refractories and alloys due to Improving the thermal efficiency, and high-temperature exposure to a variety thereby conserving energy, may be of combustion species. During this year accomplished by increasing the operat- IN Federer and Vie Tennery also pub- ing temperature of energy conversion lished a report on the degradation of devices or processes. The upper tem- refractory fibrous insulations due to perature limit for operation with con- corrosion from fuel impurities. These ventional heat resisting alloys had been were the first such experiments done in reached. An avenue for improving this the United States and resulted in wide- situation was recognized by C. T. Liu in spread recognition of ORNL. the potential of intermetallic com- pounds to allow higher operating tem- In 198 1, the industrial conservation peratures . staff started a new national DOE effort to modify the RTF in order to conduct Emphasis on the intermetallic alloys in experiments on tubular ceramic speci- the 1980s. was on Fe@, FeAl, Andy mens which could simulate components N$Al. The problem with the intermetal- of tubular ceramic heat exchangers. lit compounds is that the ductility These devices had become of major approaches zero at ambient tempera- interest for industrial waste heat recov- ture. C. T. Liu discovered that the iron

diversification and the high-technology years aluminide (Fe& could be made ductile ceramic technology. This effort was a with small chromium additions of total failure and was abandoned. The 124 about 2%, and the nickel aluminide problem was that the silicon carbide with the addition of about 200 ppm of ceramic fracture toughness was boron. inadequate and inconsistent.

These inventions provided the basis for A joint program between the ceramics potential commercial uses, and incen- group at Wright Patterson Air Force tive for development of alloys for spe- Base funded by NASA and the DOD, cific applications. The inventions them- and the M&C Division funded by the selves were funded by ORNL seed DOE Division of Research and Conser- money and the Basic Energy Sciences vation Programs, was begun in the mid programs and the BES program contin- seventies. This program was aimed at ued funding basic aspects of the work. improving the properties of a broad Development and commercialization range of ceramics for potential uses in efforts were funded mainly by the gas turbine and reciprocating engines. conservation and fossil energy pro- The basic work on toughening mecha- grams, and this work was conducted by nisms was done by Paul Becher. Vinod Sikka in the fabrication aspects and by Gene Goodwin and Mike A number of people made important Santella for welding. The total govern- contributions during the twenty years ment investment in the development since the start of the program including and commercialization of these alloys George Wei, Gary Weber, Mark Janney, has been fifteen years and about Terry Tiegs, David Stinton, and others $35 million; the industrial investment in the Ceramic Processing and Ceramic is difficult to determine but is probably Surface Systems Groups. The entire of the same magnitude. All three alloys processing sequence from powder to are currently being produced commer- consolidation to heat treatment to cially for various uses in the metals machining was improved. The proper- processing industry. ties and their consistance was im- proved in zirconia, alumina and silicon The efficiency of gas turbines had nitride. The fracture toughness of reached its upper limit in the sixties. A silicon nitride was improved by a factor large effort was funded by the of six, and is the ceramic of choice for Department of Defense to develop a gas turbine and other engine applica- ceramic gas turbine using the existing tions.

diversification and the high-technology years

introduction

The chronology of Metals and Ceramics Division Directors and Organization 126 Charts at the beginning of their tenure.

appendix 1 ORNL 99-03449/ash

A. Johnson idDirector 946-1949)

METALLURGY DIVISION w. A. .lOHNsON DIRECTOR 1

H Frye, Jr. Director 949-1973)

METALLURGY DIVISION J. H FRYE. JR. DIRECTOR

,.. E. BANKER I I ADHINISTRATIVE ASSISTANT

THORIUM ALLOY FUNDAMENTAL RESEARCH EXTRUSION DEVELOPMENT AND REACTOR METALLOGRAPHY ON OF CLlMON AND HANFORD DEVELOPMENT R. .I. GRAY BERYLLIUM A THORIUM F. KERZE. JR. BERYLLIUM SLUG PROBLEMS E. c. MILLER A. G. H. ANDERSON E. .I. BOYLE ORNL 99.03450/ash

MARTIN MARIETTA ENERGY SYSTEMS, INC.

J. R. Weir, Jr. Director (1973-1984) . ORNL 99-034Wasb D. F. Craig Director (1992-present)

LwEcmR D.F. CRUG P.H. YUER As-lE DIRE”oRS J.R. wait JR EC DUOH WA-

-4

J

n LOCKHEED MARTIW// Lackhwd Martin Energy Systems. Inc.

LOCKHEED MARTI Lockheed Martin Energy R-tsh Corp. /I

introduction

Photographs were selected for presen- was made to present photographs of as 132 tation in this appendix that represent many of the staff over as wide a time samples of the administrative staff, the frame as possible. Omissions were technical staff at some information inevitable for which the compilers meetings, and social events. An attempt apologize.

appendix 2 Standing left to right: Marge White, Melba Botfnger, Lou Pyatt, Wilma Mason, Meredith Hill, Freda Co%. Seated left to rfght: Mary Montgomery, Betty McHargue, Delores Poe, Bertfe Byrum, Jane Morrison.

- -0 0 John Frye, Bertfe Byrum, Marry Yaggf, Jack Cunningham, and Gene Banker. 3Y !,, .:.‘: ‘d i vi s i 0 n ‘s information -meetings_‘* ^r P i:: (1962) 135

Charlfe Past, Chester IWorgan, and Sfg Peterson.

Al Taboada, Al Goldman, and Cabel Finch.

appendix 2 division’s information meetings (1963) I36

Jfm Weft, Bob Swfndeman, and Bill Harms.

Charles Fox, Jim Murdock, Jack Cook, and Joe Tackett.

appendix 2 137

Unknown, Chuck Boston, John Cathcart, Dick Pawel, Ted Lundy, and Fitz Winslow.

appendix 2 division’s information meetings (1971) 138

Gene Goodwin, Clarence Wodtke, Gerry Slaughter, Al Goldman, and Artie Moorhead.

Marge White, Bob Adams, Gene Banker, and Gerry Slaughter.

appendix 2 139

Jim DiStefano and Bob mcDona,ld. ,_ _ ,,,

\

.“.,,.,

appendix 2 division’s alumni reunion (1981) 140

Jim King, Randy Nan&ad, DaveZdmonds, Stan David, and Artie Moorhead.

Bill Harms, Grace Harms, and Jfm Weir.

appendix 2 Bill Martin, Meredith Hill, Pat Row, Ted Reedy, Frances Scarbroro, Don Douglas, and Sharon Buhl. appendix 2 142

Pete Houck, Bill Leslfe,’ Leonard Williams, and Bob Crouse.

Roger Waugh, Al Goldman, and Dick Heestand

appendix 2 ‘. !,) .“C ‘: :;‘ (,

143

Dick Beaver, Jack Cunningham, and Durwood Hamby

Gerry Slaughter, Bob Gray, Ed Boyle, Sloan Bomar, and Bud Dubose appendix 2 division’s picnic (1988) 144

Greg Kern, Tony Schaffhhuser, Everett Bloom, and Jfm Stfegler

Greg Kern and Bill Miller

appendix 2 I45

Gerrg and Doris Slaughter

Standing: Orville Kimball, Charlie Devote, Terry Tiegs Seated: Peter Blau, Pete Angelfni, and Laura Riester

appendix 2 I46

Vie and Joyce Tennery

Malcolm Stocks, Everette Bloom, Claudette McKamey, and Cullfe Sparks

appendix 2 christma ..,. s,., party skit (1990)

. . - ...... -:,.: . . . For two yearsyears thethe DivisionDivision staffstaff membersmembers wrotewrote andand producedproduced a skit presented durfng the atytuala?pual Chrfstmas ce,lebratfon. This skft “The Prfncedom and the Chrfst- mas Fairy” was presented in 1990 and was wrftten’by Davfd 0. Ho&son. The cast left to right: Shirley Frykman (program manager), Holly Parkinson (page), David 0. Ho&son (the Grinch), Aprfl McMillan (program manager), Mary Ann Collins (princess), Phil Rfttenhouse (narrator), Cathy Cheverton Ifairy), Jim Weir (Merlin), Bob Swindeman (section head), Ron Swain (section head), and Jim Stiegler (the prince).

appendix 2 Christmas party skit (1991) 148

The second skit, as10 written by Dqve Hcbson, was presented in 1991. The cast left to right, Jim Weir (Merlin), Tim Burchell (loyal subject l), Cheryl Lee (Xmas spirit past), Lou Pgatt (logal subject 3), Holly Parkinson (loyal subject 2), April l&Millan (Xmas spirit present), Cathy Cheverton (Xmas spirit future), Doug Craig (assistant king 2), Harry Liveseg (king), and Ron Swain (assistant king 1).

appendix 2