l _ United States Patent [191 [11] Patent Number: 4,475,948 Cawley et al. p ' ' [45] Date of Patent: Oct. 9, 1984 [54] LITHIUM ALUMINATE/ZIRCONIUM [56] References Cited MATERIAL USEFUL IN THE PRODUCTION S PAT NT DOCUMENTS OF TRITIUM U. ' E 3,079,317 2/1963 Jenks et al. ........................ .. 376/202 [75] Inventors: William Cawley; Turner J. Trapp, 3,100,184 8/1963 Abraham ........................... .. 376/146 both of Rlchland' wash’ Primary Examiner—Leland A. Sebastian [73] Assignee: The United States of America as Attorney, Agent. or Firm-Robert Southworth, III; represented by the Department of Richard E. Constant; Michael F. Esposito Energy, Washington, DC [57] ABSTRACI [21] APPl- N°-= 488,825 A composition is described useful in the production of [22] Filed_ A r 26 1983 tritium in a nuclear reactor. Lithium aluminate particles ‘ p ' ’ i are dispersed in a matrix of zirconium. Tritium pro [51] Int. C1.3 ............................................ .. F16N 57/04 duced by the reactor of neutrons with the lithium are [52] US. Cl. .................................... .. 75/230; 376/146; absorbed by the zirconium, thereby decreasing gas pres 376/202; 420/422 sure within capsules carrying the material. [58] Field of Search ................ .. 75/230; 376/146, 202; 420/422; 501/105 ' 6 Claims, No Drawings 4,475,948 1 2 A preferred method of preparing the composition of LITHIUM ALUMINATE/ZIRCONIUM MATERIAL the present invention is to ?rst prepare lithium alumi USEFUL IN THE PRODUCTION OF TRITIUM nate powder. This powder may be advantageously pre pared using sol.-gel techniques so that uniformly sized The United States Governmentrhas rightswin this 5 particles with known properties are achieved. Brie?y, I "iinve'ntioriw "to TQorit'rac't’fNoL"DEACOE- _ aluminium oxide is dissolved in nitric acid to form an 7 V V I 7 " 76RL01857 between the US. Department of Energy aluminum nitrate solution. The aluminum nitrate solu and UNC Nuclear Industries and pursuant to Section tion is then reacted with ammonia to return aluminum 152 of the Atomic Energy Act of 1954. oxide, now in the form of an alumina sol. At this point, 10 BACKGROUND OF THE INVENTION a stoichiometric amount of a soluble lithium compound is added to the solution. Depending upon the neutronic ' ' The invention‘ relates generally to the production‘of characteristics of the reactor, it may be desirable to use tritium in anuclear reactor and, more particularly to a lithium fully enriched in the lithium isotope. The alu composition for the production’of tritium. I " ' minasol-lithium mixture is then added dropwise into a As is well known, tritium may be produced by expos bath of solvent which is at least partially immiscible in ing lithium-6 to the neutron flux in a nuclear reactor. In the alumina sol. As part of the moisture present in the the past, tritium has been manufactured by placing a zirconium capsule containing LiAlOz .withinthe nu sol is extracted into the solvent, the sol is converted into clear reactor. Because zirconium is readily hydrided, it perfect spheres of a gel. Through appropriate sizing of the drop-forming means, such as a vibrating nozzle, the is necessary to place a protective layer such as alumi 20 resulting particles will be sized between 100 and 500 num between the LiAlO; and the zirconium in order to prevent the tritium from destroying the integrity of the. micrometers. The microspheres may then be heated to capsule. drive off remaining moisture and then heated to a high As the reactor operates, gas pressure from the gener temperature to form the compound lithium aluminate. ated tritium builds up within the capsule until it be 25 Next, ?nely divided zirconium metal powder may be comes so great that the capsule must be removed to prepared by first reacting a mass of zirconium with retrieve the product before capsule failure occurs. In hydrogen to form zirconium hydride, grinding the zir order to remove the capsule, the reactor must be shut conium hydride to a ?ne powder in a ball mill, and then down. This premature shutdown disrupts the smooth dehydriding by heating in a vacuum. The resulting operation of the reactor, and is particularly uneconomic zirconium metal powder will be quite reactive and in the case of dual-purpose reactors which are also used should be handled either under vacuum or inert condi to generate electicity. tions. In view of the above, it is an object of this invention At this point, the lithium aluminate and zirconium to provide a material useful in the production of tritium. powder are mixed and blended thoroughly. In order It is another object of this invention to increase the 35 that the resulting material or cermet retain the metalur time between shut down of a tritium production reac gical properties of the zirconium, it is desireable that the tor. lithium aluminate be less than ten volume percent of the It is a further object of this invention to provide a composition. The mixture is then compressed into pel more economical method for obtaining tritium. lets and is ready for loading into capsules and use in a Other objects, advantages, and novel features of the 40 reactor. The pressing may be done by a number of well invention will be apparent to those of ordinary skill in know techniques such as cold-pressing, hot-pessing, or the art upon examination of the following detailed de sintering. The mixture may either be done to near 100% scription of a preferred embodiment of the invention. theoretical density, or some residual porosity may be left to allow room for the helium which will be gener SUMMARY OF THE INVENTION 45 ated as a co-product. A composition is provided for the production of trit The foregoing description of a preferred embodiment ium in a nuclear reactor comprising lithium aluminate of the invention has been presented for purposes of particles imbedded in a zirconium matrix. Tritium pro illustration and description and is not intended to be duced by the reaction of neutrons with the lithium is exhaustive or to limit the invention to the precise form absorbed by the zirconium, thereby decreasing gas pres— disclosed. It was chosen and described in order to best sure within capsules carrying the material. explain the principles of the invention and their practi cal application to thereby enable others skilled in the art DESCRIPTION OF A PREFERRED to best utilize the invention in various embodiments and EMBODIMENT with various modi?cations as are suited to the particular According to the invention, a composition suitable 55 use contemplated. It is intended that the scope of the for the production of tritium is lithium aluminate parti invention be de?ned by the claims appended hereto. cles imbedded in a matrix of zirconium. This composi We claim: tion is to be placed within a metallic capsule and placed 1. A composition for the generation of tritium upon within the neutron ?ux of a nuclear reactor. Lithium-6 neutron irradiation comprising lithium aluminate parti upon reaction with a neutron will be transmuted to 60 cles imbedded in a zirconium matrix. tritium and helium. These gases will tend to pressurize 2. The composition of claim 1 wherein the lithium the metallic capsule to the point that the reactor must be aluminate comprises up to ID volume percent of the shut down to remove the capsule. composition. However, with the present invention, the tritium will 3. The composition of claim 1 wherein the lithium react with the zirconium matrix forming zirconium 65 aluminate particles are between 100 and 500 microme hydride. This will tend to result in lower gas pressure in ters in diameter. the capsule and thereby increase the time between reac 4. The composition of claim 1 wherein the lithium is tor shutdowns and improve the reactor economics. enriched in lithium-6. 4,475,948 3 4 t 5.1The composition of claimv lwherein said composi (c) adding a lithium containing solution to the alu= mina sol; tion prepared by; _ Y' r (d) forming microspheres of a gel by exposing drop~ _ (3) Preparing particles of lithium ,aluminate with a 5 . li.i_iQ--..i(c)rmixingr thempowdered lawman-metal "and the" (t) converting the dried microspheres into lithium '7 ’ aluminate particles by sintering; lithium aluminate particles; and (g) reacting zirconium metal with hydrogen to form (d) subjecting the mixture to pressure to form pellets 10 zirconium hydride; of zirconium/lithium aluminate cermet. (h) reducing the zirconium hydride to a ?ne powder; ' " '6? The composition of claim 1 wherein said 'éomp‘osié (i) converting the powdered zirconium hydride to " AMA-MW -- ?ends-prepared»byPM» -~- -~ ~ powdered zirconiummsml by heating in =2 vacuum; "0) mixing the powdered 'zirconiurn‘and the lithium‘ \ ~(a) dissolving alumina in nitric acid to form an alumni? 15' aluminate particles; and num nitrate solution; (k) subjecting the mixture to pressure to form pellets (b) reacting the aluminum nitrate solution with am of zirconium/lithium aluminate cermet. c c t t t v ' ' ' monia to form an alumina sol; ~ -» 1 20 25 30 35 50 55 65 .