Study of thorium advanced fuel cycle utilization in light water reactor VVER-440

The first step in investigation of thorium fuel is evaluation of the results obtained from the spectral code for this type of fuel. The benchmark summarized by IAEA in 2003 was used for partial validation of the code HELIOS 1.9. The benchmark was focused on a comparison of the methods and basic nuclear data. Acceptable results of benchmark comparison allowed examining and comparing different advanced nuclear fuel cycles under light water reactor conditions, especially in VVER-440. Cycles, calculations and results for VVER-440 reactors are presented in the paper. Two of the investigated thorium based fuels include one solely plutonium–thorium based fuel, while the other one is a plutonium–thorium based fuel with a content of reprocessed uranium. The third examined fuel cycle is a cycle with an inert-matrix fuel consisting of reprocessed plutonium and minor actinides (MA) fixed in an yttria-stabilized zirconium matrix. All of them are used to carry and burn or transmute plutonium created in the classical UOX cycle. The Pu transmutation rate and cumulating of Pu with MA in the spent fuel were compared mutually and with an UOX open cycle. The fuel cycle with an inert-matrix fuel was proven to be the best cycle for minimizing the production of Pu in the VVER-440 reactors.