Abstract

Nonpower reactors licensed by the U.S. Nuclear Regulatory Commission require a startup test plan as part of any facility modification to verify operability prior to resumption of operations. In order to support conversion of the University of Missouri Research Reactor from the use of highly enriched uranium to low-enriched uranium (LEU) fuel, a startup test plan has been devised to measure certain reactor physics parameters for the initial all-fresh LEU core licensing documentation that will be submitted. These parameters include the approach to critical, primary coolant void coefficient of reactivity, flux trap void coefficient of reactivity, determination of flux trap sample reactivity worth, radial and axial thermal neutron flux mapping, control blade worth calibration, primary and pool coolant temperature coefficient of reactivity, and flux mapping of experimental positions. In this paper, predictions for these parameters made using the Monte Carlo N-Particle Version 5 (MCNP5) radiation transport code are reported. These predictions will support the startup tests by providing a baseline set of expectations and additional insight into the performance of the LEU core.

摘要

美国核监管委员会许可的非动力反应堆需要启动测试计划，作为任何设施修改的一部分，以在恢复运行之前验证可操作性。为了支持密苏里大学研究堆从使用高浓铀到低浓铀（LEU）燃料的转化，已经制定了启动测试计划，以测量最初的全新鲜LEU堆芯的某些反应堆物理参数。将要提交的许可文件。这些参数包括关键，主要冷却剂无效反应系数，通量陷阱无效反应系数，通量陷阱样品反应系数确定，径向和轴向热中子通量图确定，控制叶片标定，主要和池冷却液温度系数的确定方法。反应性 和实验位置的流量映射。在本文中，报告了使用蒙特卡洛N粒子第5版（MCNP5）辐射传输代码对这些参数进行的预测。这些预测将通过提供一组基准期望值以及对LEU核心性能的更多见解来支持启动测试。