Utilization of rock-like oxide fuel in the phase-out scenario

Abstract

Utilization of rock-like oxide (ROX) fuel in light water reactors for plutonium (Pu) burning was studied by nuclear material balance (NMB) analysis for a case of Japanese phase-out scenario under investigation after the Fukushima accident. For the analysis, the NMB code was developed with features of accurate burn-up calculation, flexible combination of reactors and fuels, and an ability to estimate waste and repository. Three scenario groups of once-through Pu burning in mixed oxide (MOX) fuel and in ROX fuel were analyzed. Using two full-MOX or full-ROX reactors the Pu amount is reduced to about one-half and the isotopic vector of Pu deteriorated for being used as a nuclear weapon, especially in terms of spontaneous fission neutron generation. Effects of ROX reactors are more significant than MOX reactors in terms of both reduction in the Pu amount and deterioration of the isotopic vector. Repository footprint and potential radiotoxicity are not reduced by the MOX and ROX reactors because the heat and toxicity of MOX and ROX spent fuels are considerably high.

NMB4.0: development of integrated nuclear fuel cycle simulator from the front to back-end

“…The corrected time step D ti is given so that it has the same number density as the analytical solution for each nuclide. With the definition of a vector D t which consists of D ti , the normal and transposed OEM are defined as equations ( 7) and (8), respectively:…”

“…However, the conditions of back-end simulation are considered to be limited using these codes because they do not track the necessary nuclides to analyze the diverse and variable scenarios. Although FAMILY-21 [7] and NMB3.0 [8] were developed to simulate the Japanese nuclear fuel cycle, they are specialized for mass balance analysis of actinide nuclides for mainly using fast breeder reactors (FBR) and accelerator driven nuclear transmutation system (ADS). Therefore, nuclear fuel cycle codes that flexibly simulates not only the front-end but also the back-end has not been developed.…”

Transmutation Scenarios after Closing Nuclear Power Plants

“…In comparison between LWR-OT and LWR-PuT, reductions are observed in Pu amount, repository footprint, and decay time of toxicity, although they are not drastic. Important benefits of MOX utilization are Pu isotopic deterioration as a nuclear weapon and improved confinement of radionuclides by calcinations, as discussed by Nishihara et al [7]. However, there remains 110 t of separated Pu that can raise concerns about proliferation.…”

“…The NMB code [7] was employed for the scenario analysis. The code calculates material balance of 26 actinides (through Th to Cm, T 1/2 > several days) in spent fuels with an accuracy comparable to the ORIGEN2 code.…”