Feasibility Study On Burnable Absorber For Forseti To Reduce Productions Of Pu238 And Pu241

To reduce the radiotoxicity of transuranium nuclides, Fuel cycle Of light water Reactor with Surplus Enriched Uranium for Transuranium-production Inhibition (FORSETI) has been studied. Since the potential radiotoxicity in spent fuel of FORSETI is mainly due to Pu238 and Pu241, the present study discusses the inclusion in FORSETI of a burnable absorber to reduce productions of these nuclides. Impacts of burnable absorbers on reaction rates related to productions of Pu238 and Pu241 are investigated by Monte Carlo calculations. The results show that Dy162, Er162, and Hf179 can reduce the production of Pu238 by suppressing the capture reaction of U236, and Hf177 can reduce the production of Pu241 by suppressing the capture reaction of Pu240. By comparing cross sections and capture reaction rates, it is confirmed that the suppression is mainly caused by the overlap of the resonances. Results of depletion calculations show that Dy162 and natural dysprosium suppress the production of Pu238, and Hf177 and natural hafnium suppress the production of Pu241. The present study concluded that Dy162 and natural dysprosium are candidates of the burnable absorber for FORSETI since they are suitable for further reduction of the potential radiotoxicity of transuranium nuclides through 50 years after discharge.