Transport of radioactive corrosion products in primary system of sodium-cooled fast breeder reactor "MONJU"

Matsuo, Yoichiro; Hasegawa, Masanori; Maegawa, Yoshiharu; Miyahara, Shinya  

Radioactive corrosion products (CP) are primary cause of personal radiation exposure during maintenance work at FBR plants with no breached fuel. The PSYCHE code has been developed based on the solution-precipitation model for analysis of CP transfer behavior. We predicted and analyzed the CP solution and precipitation behavior of MONJU to evaluate the applicability of the PSYCHE code to MONJU, using the parameters verified in the calculations for JOYO. From the calculation result pertaining to the MONJU system, distribution of Mn deposited in the primary cooling system over 20 years of operation is predicted to be approximately 7 times larger than that of Co. In particular, predictions show a notable tendency for Mn precipitation to be distributed in the primary pump and cold-leg. The calculated distribution of Mn and Co in the primary cooling system of MONJU agreed with tendencies of measured distribution of JOYO.