Development of measurement technique on the equilibrium vapor pressure of simulated fission products

Takai, Toshihide  ; Nakajima, Kunihisa  ; Furukawa, Tomohiro  ; Osaka, Masahiko  

Improvement of the serve accident analysis code is important to evaluate the distribution of the released fission products (FPs) in the reactor more precisely from the view point of both the removal preparation of the fuel debris in the Fukushima Daiichi Nuclear Power Station and improved source term evaluation. The development of the calculation model, which can evaluate the effect of atmosphere and the chemical reaction between the released FPs and control rod material (BC) at elevated temperature, is important for this purpose. The measurement technique of the equilibrium vapor pressure using a high temperature mass spectrometer was under development to expand the thermodynamic database of the simulated FPs, because the chemical equilibrium analysis plays an important role to clarify the effect of chemical reactions. In this study, the apparatus was developed for the equilibrium vapor pressure measurements, and then the reliability of measurement results was evaluated.