IER 203 CED-2 Report: LLNL Final Design for BERP Ball With a Composite Reflector of Thin Polyethylene Backed by Nickel

Percher, C. M.¹  Heinrichs, D. P.¹  Kim, S. K.¹ 

[1] Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

关键词: NICKEL;    LAWRENCE LIVERMORE NATIONAL LABORATORY;    PLUTONIUM-ALPHA;    POLYETHYLENES;    SPHERICAL CONFIGURATION;    DESIGN;    CRITICALITY;    NEUTRON REFLECTORS;    SPHERES;   

DOI  :  10.2172/1289363
RP-ID  :  LLNL--TR-698019
PID  :  OSTI ID: 1289363

学科分类：工程和技术（综合）

美国|英语

来源: SciTech Connect

【 摘 要 】

This report documents the results of final design (CED-2) for IER 203, BERP Ball Composite Reflection, and focuses on critical configurations with a 4.5 kg ??-phase plutonium sphere reflected by a combination of thin high-density polyethylene (HDPE) backed by a thick nickel reflector. The Lawrence Livermore National Laboratory???s (LLNL???s) Nuclear Criticality Safety Division, in support of fissile material operations, calculated surprisingly reactive configurations when a fissile core was surrounded by a thin, moderating reflector backed by a thick metal reflector. These composite reflector configurations were much more reactive than either of the single reflector materials separately. The calculated findings have resulted in a stricter-than-anticipated criticality control set, impacting programmatic work. IER 203 was requested in response to these seemingly anomalous calculations to see if the composite reflection effect could be shown experimentally. This report focuses on the Beryllium Reflected Plutonium (BERP) ball as a fissile material core reflected by polyethylene and nickel. A total of four critical configurations were designed as part of CED-2. Fabrication costs are estimated to be $98,500, largely due to the cost of the large nickel reflectors. The IER 203 experiments could reasonably be expected to begin in early FY2017,