Critical Configuration and Physics Measurements for Assemblies of U(93.15)O2 Fuel Rods

Margaret A. Marshall

关键词: NESDPS Office of Nuclear Energy Space and Defense Power Systems;    acceptable benchmark;    cadmium ratios;    close packed;    critical experiments;    dioxide;    fission rates;    graphite reflected;    highly enriched;    reactivity worth measurements;    unmoderated;    uranium;   

DOI  :  10.2172/1129114
RP-ID  :  INL/EXT-11-23295
PID  :  OSTI ID: 1129114

美国|英语

来源: SciTech Connect

【 摘 要 】

A series of critical experiments were completed in 1962-1965 at Oak Ridge National Laboratory???s (ORNL???s) Critical Experiments Facility (CEF) in support of the Medium-Power Reactor Experiments (MPRE) program. In the late 1950s, efforts were made to study ???power plants for the production of electrical power in space vehicles.???(a) The MPRE program was a part of those efforts and studied the feasibility of a stainless-steel system, boiling potassium 1 MW(t), or about 140 kW(e), reactor. The program was carried out in [fiscal years] 1964, 1965, and 1966. A summary of the program???s effort was compiled in 1967. The delayed critical experiments were a mockup of a small, potassium-cooled space power reactor for validation of reactor calculations and reactor physics methods. Initial experiments, performed in November and December of 1962, consisted of a core of unmoderated stainless-steel tubes, each containing 26 UO2 fuel pellets, surrounded by a graphite reflector. Measurements were made to determine critical reflector arrangements, fission-rate distributions, and cadmium ratio distributions. Subsequent experiments used beryllium reflectors and also measured the reactivity for various materials placed in the core. ???The [assemblies were built] on [a] vertical assembly machine so that the movable part was the core and bottom reflector.???(Reference 1) The experiment studied in this evaluation was the first of the series and had the fuel tubes packed tightly into a 22.87 cm outside diameter (OD) core tank. Two critical configurations were found by varying the amount of graphite reflector (References 1 and 2). Once the critical configurations had been achieved, various measurements of reactivity, relative axial and radial activation rates of 235U, , and cadmium ratios were performed. The cadmium ratio, reactivity, and activation rate measurements performed on the critical configurations are described in Sections 1.3, 1.4 and 1.7, respectively. Information for this evaluation was compiled from References 1 and 2, reports on subsequent experiments in the series , and the experimental logbook, and from communication with the experimenter, John T. Mihalczo.