Preliminary Accident Analyses for Conversion of the University of Missouri Research Reactor (MURR) from Highly- Enriched to Low-Enriched Uranium.

摘要

This report contains the results of reactor accident analyses for the University of Missouri Research Reactor (MURR). The calculations were performed as part of the conversion from the use of highly-enriched uranium (HEU) fuel to the use of low-enriched uranium (LEU) fuel. The analyses were performed by staff members of the Global Threat Reduction Initiative (GTRI) Reactor Conversion Program at the Argonne National Laboratory (ANL) and the MURR Facility. The core conversion to LEU is being performed with financial support from the U. S. government. In the framework of its non-proliferation policies, the international community presently aims to minimize the amount of nuclear material available that could be used for nuclear weapons. In this geopolitical context most research and test reactors, both domestic and international, have started a program of conversion to the use of LEU fuel. A new type of LEU fuel based on an alloy of uranium and molybdenum (U-Mo) is expected to allow the conversion of U.S. domestic high performance reactors like MURR. This report presents the results under a set of accident conditions for MURR cores fueled with HEU U-Alx dispersion fuel or LEU monolithic U-Mo alloy fuel with 10 wt% Mo. For the proposed LEU-fueled core, previous studies have shown that in order to maintain the neutron flux and current levels at various crucial experimental locations within the reactor at the same level after the fuel conversion from the HEU to LEU, the steady-state operating power level must be increased from 10 MW to 12 MW. Hence the accidental positive reactivity insertions, and the loss of coolant and loss of flow accidents for the LEU core were initiated from an initial steady-state power level of 12 MW. It is noted that all references to the core power level for MURR are the thermal power output of the reactor (i.e., MWt).