ZEUS: Fast-spectrum critical assembly with a mixed core of highly enriched and natural uranium containing lead surrounded by a copper reflector

Oizumi, Akito; Fukushima, Masahiro; Gunji, Satoshi; McKenzie, G.*; Amundson, K.*

International Criticality Safety Benchmark Evaluation Project (ICSBEP) Handbook (2022/23 edition) (Internet) , 313 Pages, 2024/11

This benchmark report was compiled to register a critical experiment using the lower-enriched uranium (LEU) system core to the International Criticality Safety Evaluation Project (ICSBEP). The LEU experiment was one of a series of joint experimental project with the Los Alamos Laboratory in the United States from 2015 to 2019 aimed at improving the design accuracy of the accelerator driven system (ADS). This core was loaded alternating highly-enriched uranium (HEU) and natural uranium (NU) to simulate LEU. In addition, a fast neutron spectrum system was constructed with not only HEU and NU but also lead which is part of coolant in the ADS. In this evaluation, it was clarified that the experimental uncertainty for the effective multiplication factor was almost 100 pcm. Moreover, the C/E-1 values of almost -70 pcm and -145 pcm were obtained by the calculation with the continuous energy Monte Carlo code MCNP and the nuclear data ENDF/B-VIII.0 and JENDL-4.0, respectively.