Calculation of Nuclear Characteristic Parameters and Drawing Subcriticality Judgment Graphs of Infinite Fuel Systems for Typical Nuclear Fuels

摘要

Nuclear characteristic parameters were calculated and subcriticality judgment graphs were drawn for revision of the Data Collection for the Nuclear Criticality Safety Handbook. The calculated nuclear characteristic parameters were the neutron multiplication factor in infinite media, migration area and diffusion constant for 11 kinds of typical fuels encountered in criticality safety evaluation of nuclear fuel cycle facilities. These fuels included ADU-H_2O, UF_6-HF and Pu(NO_3)_4-UO_2(NO_3)_2 solution, of which data were not cited in the Data Collection. The calculation was made with the Japanese Evaluated Nuclear Data Library JENDL-3.2 and a sequence of criticality calculation codes, SRAC, POST and SIMCRI. The subcriticality judgment graphs that depict the region of the two variables (a) uranium enrichment, ~(239)Pu/Pu ratio or plutonium enrichment and (b) H/(Pu+U) ratio where the neutron multiplication factor in infinite media k_∞ ≤ 0.98 were drawn for the same kinds of fuels except UF_6-HF. The limitations of the subcriticality judgment graphs were also discussed.