GNEP-Sponsored Feasibility Studies of MOX Fuel Cycles in American BWRs and PWRs

摘要

The BWR results of this work have shown thefeasibility of a 24-month cycle with a reload batchfraction of 50% MOX in a BWR-5 764 assemblycore. The core MTC and SBLCS shutdowncapability are acceptable with a slight increase inthe SBLCS boron concentration.The PWR results of this work have shown thefeasibility of an 18-month cycle with reload batchfraction of 10% to 30% MOX in a four-loop 193assembly PWR. Soluble boron enriched in the B10isotope will be needed for the MOX cycles tominimize the hot full power, hot zero power andcold shutdown boron concentrations. Shutdownmargins are acceptable in these cycles. The effect ofthe MOX assemblies on pressure vessel fast (> 1.0Mev) neutron fluence remains to be assessed. Thepin pressure in the MOX assemblies has not beenassessed, and the neutronic and economic effects ofhaving a slightly shorter fuel stack length in theMOX assemblies to relieve pin pressure have notbeen assessed. The PWR MOX cycles show gainsin equilibrium cycle length versus the referenceLEU (non-MOX) cycle for the same LEUenrichments.