Analytical Study of Sodium Fire Characteristics under Sodium Leak Accidents

The use of sodium as a coolant in a liquid metal reactor(LMR) has many advantages due to its thermal properties while a disadvantage that a major sodium spill and a pipe rupture of sodium coolant systems will usually result in a sodium fire. The rise of temperature and pressure, the release of aerosol in the buildings as a result of a sodium fire must be considered for the safety measures of a LMR. Subsequent effect of a sodium fire depends upon whether the sodium continues to leak from the pipe or not, whether the ventilation system is running, whether the inert gas injection system is provided, whether the sodium on the floor is drained into the smothering tank or not, whether the building is sealed or not, etc. Therefore, for the safety of a LMR, it is necessary to understand the characteristics of a sodium fire, resulting from various types of leakage. ASSCOPS(Analysis of Simultaneous Sodium Combustion in Pool and Spray) is the computer code for the analysis of the thermal consequences of a sodium leak and fire in a LMFR that has been developed by JAEA in Japan. Computer code includes two sodium combustion codes called SOFIRE II and SPRAY. SOFIRE II code has been developed to compute 1-cell and 2-cell pool fire cases by Atomics International(AI), and the SPRAY code has been developed to evaluate the consequences of a postulated sodium spray release from LMFR piping leak by Hanford Engineering Development Laboratory(HEDL) in USA. This study describes a preliminary analysis of sodium leak and fire accidents in the S/G building of KALIMER. Various phenomena of interest are the spray and pool burning, peak pressure, temperature change, the drain system into the smothering tank, ventilation characteristics at each cell with the safety venting system and nitrogen injection system