Design study of key technology for large LMFBR (II); Sodium fire analysis

Morii, Tadashi*; Himeno, Yoshiaki

Sodium fire analysis has been performed for a large FBR to evaluate pressure and temperature transients and mass of burned sodium in case of a primary sodium leak accident. The major analytical conditions are as follows: [Position of sodium leak : Hot leg of primary coolant system] [Cross-sectional area of a leak hole : 1 cm] [Concrete cooling system : operated (just before failure), shut down (after sodium leak)] The most representative results gained through the present study are as follows: [Maximum Gas Pressure : 0.029 kg/cm2 -g (0.5 hr after a leak)] [Total Mass of Burned Sodium : 1.5 ton (3% of total leak sodium)] [Maximum Concrete Temperature (beneath sodium pool) : 140C (100 hr after a leak) These results indicate that a concrete cooling system to present abnormal temperature rise that may occure due to heat transfer from the hot primary coolant system was shown to be effective even in the accident conditions. However, further study will be needed to evaluate water release rate from the heated concrete.