1st quarter 2000 TheLos Actinide Alamos National Research Laboratory N u c l e a r M aQuarterly t e r i a l s R e s e a r c h a n d T e c h n o l o g y a U.S. Department of Energy Laboratory Organizers Issue an Invitation to In This Issue Plutonium Futures 1 —The Science Organizers Issue an Invitation to Plutonium Futures —The Science The second of a series of international con- have an exciting collection of some 180 invited ferences on plutonium will be held in Santa Fe, and contributed papers with topics ranging 2 NM, this summer, July 10–13. It follows the very broadly in materials science, transuranic 238Pu Aqueous highly successful 1997 conference, “Plutonium waste forms, nuclear fuels and isotopes, separa- Processing Line Will Futures - The Science,” which attracted over 300 tions, actinides in the environment, detection Provide New NMT participants representing 14 countries. The U.S. and analysis, actinide compounds and com- Capability participants, who made up about 70 percent of plexes, and condensed matter physics of ac- the total participants, came from Department of tinides. These papers, presented in separate 4 Energy national laboratories and a score of uni- oral and poster sessions, will give attendees a Editorial: versities and industries. As in 1997, the confer- chance to learn about current research outside Transactinium ence is sponsored by the Los Alamos National of their particular specialties and provide an Science Needs Laboratory in cooperation with the American opportunity for interdisciplinary discussions Educational Nuclear Society. among the participants. Rearmament—A From the beginning, the conference orga- For this year’s conference program, two Strategic Reinvest- nizers recognized that there are a multitude of striking features to be noted are a dramatic ment for the Nation issues surrounding plutonium and other ac- increase in international papers and a signifi- tinides and that both short- and long-term solu- cantly increased number of students who have 6 tions to managing the global nuclear materials contributed papers. Both aspects of this confer- “Plutonium Futures threat rest ultimately on the scientific and tech- ence are welcome developments after extensive —The Science” nological knowledge base. Thus, one of the efforts by the organizers and a few support Preliminary main objectives of the conference is to provide staff at Los Alamos who have communicated Conference Program an opportunity to present and assess our cur- with colleagues worldwide. rent understanding of plutonium and actinide With the presentation of the conference 24 sciences and to focus on the science needed for preliminary program in Actinide Research Quar- NewsMakers solving important national and international terly, the organizers also wish to acknowledge issues associated with plutonium. Another the Basic Energy Science Office of Department equally important objective is to inform the of Energy for providing funds for the students’ public, our stakeholders as well as the scientists, participation and the Associate Laboratory and to attract today’s students who will carry Directorates for Nuclear Weapons and Threat on the task of solving the nuclear issues Reduction at Los Alamos for their into the next century. generous support of the conference. We are pleased to present the Hope to see you all at the preliminary conference program in conference in July. this issue of Actinide Research Quar- terly. As in the first conference, we Conference Program Co-Chairs K. C. Kim and Sam Pillay Nuclear Materials Research and Technology/Los Alamos National Laboratory 1 Actinide Research Quarterly 238Pu Aqueous Processing Line Will Provide New NMT Capability A 238Pu aqueous scrap recovery glove box increased safety and high-loading-capacity line is being built at the TA-55 Plutonium Fa- characteristics. This work led to the formula- This article was cility with an annual throughput capacity of tion of the polyvinylpyridine-based Reillex- contributed by several kilograms 238Pu. This new capability HPQ resin. The studies showed the resin to be M. E. Pansoy- within NMT Division is anticipated to be in resistant to radiolytic and thermal degradation Hjelvik (NMT-9). operation by fiscal year 2001 and further sup- and to display comparable or superior sorp- Others involved ports NMT’s role as a lead DOE facility for tion kinetics in comparison to several other in this work are plutonium processing. polystyrene-based resins used for actinide pu- J. Laurinat The aqueous line is designed to purify rification. Based on these studies, the Reillex- (WSRTC) and 238Pu-oxide (238PuO ) fuel, used in the fabrica- HPQ anion exchange resin was chosen for J. Nixon, 2 tion of general-purpose heat sources (GPHS) 238Pu aqueous processing. J. Brock, or light-weight radioisotope heater units Bench-scale experiments are being con- G. Silver, (LWRHUs). The heat sources supply the ther- ducted to demonstrate that high levels of im- M. A. Reimus mal energy used in thermoelectric generators purities are separated from 238Pu solutions us- and to power spacecraft for deep space missions ing Reillex-HPQ resin, and to determine if K. B. Ramsey and to heat critical components in the cold chemical pretreatment is necessary to maintain (NMT-9). environs of space. The Power Source Tech- the 238Pu in the (IV) oxidation state. The results nologies Group, NMT-9, has manufactured of the bench-scale experiments also determine LWRHUs for use in the NASA space program the baseline operation method to be used for for approximately 20 years (see Fig. 1). More the full-scale process. Other work in collabora- recently, Los Alamos manufactured the tion with Westinghouse Savannah River Tech- GPHSs to power the spacecraft in the Cassini nology Center (WSRTC) involves heat transfer mission to Saturn (See Actinide Research Quar- calculations to determine the thermal gradi- terly, Fall 1996 and Summer 1997). ents expected during ion exchange processing. 238 The purification of PuO2 is necessary It is the Pu(IV)-hexanitrato complex in 7 because of unacceptable levels of 234U and molar (M) nitric acid that sorbs onto the other impurities in scrap fuel. Impurities at Reillex-HPQ resin during ion exchange. Main- levels above GPHS and LWRHU specifica- taining all of the Pu in the (IV) tetravalent state tions may impair the performance of the heat is difficult because of the high oxidizing envi- sources. The purification involves a nitric ronment that develops in 7 M nitric acid con- acid/hydrofluoric acid reflux of the oxide taining 238Pu. Most of the plutonium in 7 M powder, followed by oxalate precipitation and nitric acid is expected to exist in the Pu(IV) filtration. In cases where the 238Pu material tetravalent state. However, the high alpha ac- contains gross levels of impurities, it is neces- tivity of 17 Ci/gm 238Pu results in an increased sary to treat it through the nitrate anion ex- oxidizing environment (more oxidizing radi- change process before the oxalate precipita- olysis products), which results in the forma- tion step. Plutonium-238 recovered from other tion of Pu(VI). The hexavalent state weakly material and various waste forms will eventu- sorbs to the resin leading to Pu breakthrough ally be processed through the aqueous line. in the effluent waste solutions and low ion With the expected high levels of impurities in exchange efficiencies. this material, nitrate anion exchange becomes Our bench-scale studies show that chemi- an important unit operation in the 238Pu aque- cal pretreatment is important for maintaining ous scrap recovery line. The bench-scale ex- 238Pu in the (IV) valence state. Greater than 99% perimental efforts in performing nitrate anion efficiencies using 3 to 5 grams of 238Pu in nitric exchange for 238Pu purification are summa- acid solutions have been achieved with chemi- rized in this article. cal pretreatment. Chemical pretreatment was Previous research at Los Alamos in col- accomplished using urea, ferrous ammonium laboration with Reilley Industries focused sulfate, and sodium nitrite. Similar results on producing an anion exchange resin with were obtained using ferrous sulfamate instead 2 Nuclear Materials Research and Technology/Los Alamos National Laboratory 1st quarter 2000 of ferrous ammonium sulfate. Without chemi- cal pretreatment a large percentage of 238Pu is lost to the effluent and wash streams, most likely as the Pu(VI) species. The results of experiments in which the 238Pu solution had been spiked with high levels of GPHS impurities showed that decontamination factors as high as 103 are achievable. The heat transfer calculations determined the maximum bed temperature during load- ing, washing, or elution for normal column (continual flow) operation and the equilibrium temperature for no flow through the column. The constants in the calculations were 75 grams of 238Pu loaded onto 1.6 liters of resin in a 3-inch-diameter Pyrex column. The param- eters varied were 238Pu concentration, flow rate, and temperature of the Pyrex column outside wall. The results of the heat transfer calculations indicate that under full-scale op- erating conditions, the maximum resin bed temperature does not exceed 60°C. The opera- tion of ion exchange columns below this tem- perature is deemed safe in safety review stud- ies of ion exchange columns in nuclear processing. The results of the heat transfer calculations are available, as necessary, for process hazards analysis of the full-scale ion exchange operation. The heat transfer calculations were based expected to have high levels of thorium, which Figure 1. The 238Pu on a previous study at WSRTC in support of must be decreased to below the GPHS specifi- aqueous recovery glove the 238Pu production campaign to provide ma- cation of 0.5% during the purification process. box line is being built at terial to Los Alamos National Laboratory for In the past this has proven to be difficult be- the TA-55 Plutonium heat source fabrication.