PLUTONIUM ROCK-LIKE OXIDE FUEL (ROXF) SYSTEM, THEIR ONCE-THROUGH BURNING AND USAGE

摘要

The ROXf is a kind of inert matrix fuel U-238-freematrices,it has a high plutonium transmutation capability.The ROXf consists of chemically stable phases offluorite ‘stabilized ZrO_2 or ThO_2, and spinel MgAl_2O_4. Inthis fuel, PuO_2 is solidified in a fluorite phase. With U-238-Free matrices, a large part of the plutonium can beburned after irradiation in conventional LWRs. The spentROXf consists of natural analogous geologically stablephases , and is disposed directly as high level wastes‘HLWs’ after about 50 years cooling. From the highplutonium burn up rate and the high stability of the fuel, theROXf-LWRs system has proliferation resistance andenvironmental safety. Characteristics of two types of ROXf, Zr-ROX and Th –ROX with weapons-Pu ,in an LWR corearrangement are evaluated by cell burn up calculations and2-D core calculations using the SRAC code system andJENDL-3 nuclear library. In an LWR of moderator to fuelvolume ratio = 1.9 , which corresponds to current PWRs ,Pu transmutation rates with the two types of ROXf are largeenough and more than 80% and 99% of Pu and Pu-239 ,respectively, can be burned. The calculated kineticparameters indicate less moderate characteristics of ROXcores, especially with Zr-ROX .The fertile Th-232 in Th-ROX works like U-238 in the UO_2 fuel ,making kineticparameters more moderate and reactivity drop due to burnup smaller than that Zr-ROX. The neutron capture of Th-232 to generate U-233 , causes the safeguards problem.Thus , the characteristics of Zr-ROX as a typical example ,were investigated in this study