Abstract
At the fast critical assembly (FCA) of JAEA, central fission rate ratios for TRU such as 237 Np, 238 Pu, 239 Pu, 242 Pu, 241 Am, 243 Am, and 244 Cm were measured in the seven uraniumfueled assemblies (FCA-IX assemblies) with systematically changed neutron spectra. The FCA-IX assemblies were constructed with simplicity both in geometry and composition. By virtue of these FCA-IX assemblies where the simple combinations of uranium fuel and diluent (graphite and stainless steel) in their core regions were systematically varied, the neutron spectra of them cover from the intermediate to fast one. Taking their advantages, benchmark models with respect to the central fission rate ratios had been recently developed for the evaluation of the TRU’s fission cross sections. As an application of these benchmark models, the Japanese Evaluated Nuclear Data Library JENDL-4.0 was utilized by a Monte Carlo calculation code. Several results show large discrepancies between the calculation and experimental values. The benchmark models would be well suited for the evaluation and modification of the nuclear data for the TRU’s fission cross sections.
Highlights
In studies on the evaluation and modification of nuclear data, integral and differential experiments have complementarity relations
Seven uranium-fueled assemblies (FCA-IX assemblies) with systematically changed neutron spectra were constructed at the fast critical assembly (FCA) in the 1980s, and the central fission rate ratios (CFRRs) were measured for seven TRU nuclides containing minor actinides, 237Np, 238Pu, 239Pu, 242Pu, 241Am, 243Am, and 244Cm [1,2]
We reviewed the three-dimensional benchmark models for the CFRRs of the FCA-IX assemblies with systematically changed neutron spectra and discussed benchmark results by JENDL4.0
Summary
In studies on the evaluation and modification of nuclear data, integral and differential experiments have complementarity relations. Each was a coupled system comprising a central core region and a surrounding blanket region with depleted uranium metal blocks. They were simple, both in geometry and composition. Each core region was composed of a simple combination of high enriched uranium (HEU) and graphite in the assemblies IX-1 to IX-3 and that of HEU and stainless steel in the assemblies IX-4 to IX-6. Their neutron spectra cover from the intermediate to fast ones by varying the combinations of fuel and loaded diluent. The assembly IX-7 was constructed as a low enriched uranium (LEU)
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