Fission-Product Effects in Molten Chloride Fast-Reactor Fuels
Thanks are due to Arthur Tevebaugh for many helpful discussions and for suggesting this approach. This work was carried out under the auspices of the USAEC.
M. G. Chasanov
Argonne National Laboratory Argonne, Illinois
Received March 2, 1965 Revised May 28, 1965
The use of the molten chlorides as fast-reactor fuels has been given consideration in the past1-3; recently, a mobile-fuel fast reactor has been proposed4 consisting of 30 to 50 mole% (Pu, 238U)Cl3 dissolved in a molten mixture of NaCl and KCl, which is to be contained in Hastelloy-N (INOR-8, an alloy of nickel, molybdenum, iron, and chromium). Such molten chloride systems have numerous attributes, which make them attractive to the reactor physicist and engineer; however, since high fuel burnup is an ultimate goal, these systems must also be examined in the light of the chemical effects of large quantities of fission products on fuel performance and stability. Such analyses have been carried out for UO2 (Ref. 5), UF4 (Ref. 6), and UCl4 (Ref. 7). The purpose of this technical note is to estimate these effects for fast- neutron irradiation of PuCl3 in a molten chloride fuel.
The fission-product yield distributions used in the following calculations are those estimated by Burris and Dillon8 for 239Pu irradiation with fast neutrons. The yield distributions presented by them are for about 2- MeV neutron irradiation of 239Pu. In large ceramic- fueled fast reactors most fission events occur at energies between 1 and 100 keV; in small high-metal–density fast reactors the average fission energy is several hundred keV (Ref. 9). Comparison of mass-distribution fission- product curves10 with the estimates of Burris and Dillon indicate that what error occurs from the use of higher- energy neutrons instead of those of average fission energy is undoubtedly negligible except in the mass number region between 115 and 125; even there the deviation should have little effect on the final conclusions because of the low fission yields in that region.