Development of LEAP-JET Code for Sodium-Water Reaction Analysis - Validation by Sodium-Water Reaction Tests (SWAT-1R) -

Seino, Hiroshi ; Ono, Isao*; Hamada, Hirotsugu  

The sodium-water reaction event of FBR steam generator (SG) has an influence on the safety, economical efficiency, etc. of the plant, so that the selection of design base leak (DBL) of the SG is considered one of the important matters. The development of an analysis model is necessary to estimate the sodium-water reaction phenomenon with high accuracy and rationality in selecting the DBL of large SGs. The reaction jet model is pointed out as a part of the necessary improvements to evaluate the overheating tube rupture, since the behavior of overheating tube rupture is largely affected by the reaction jet conditions outside the tube. Therefore, the LEAP-JET code has been developed as an analysis code for the simulation of sodium-water reactions. This document shows the validation of the LEAP-JET code by the Sodium-Water Reaction Test (SWAT-1R). The following results have been obtained. (1) The reaction rate constant: K is estimated at between 0.001K0.1 from the LEAP-JET analysis of the SWAT-1R data. (2) The analytical results on the high-temperature region and the behaviors of reaction consumptions (Na, H2O) and products (H2, NaOH, Na2O) are considered to be physically reasonable. (3) The LEAP-JET analysis shows the tendency of overestimation in the maximum temperature and temperature distribution of the reaction jet. (4) In the LEAP-JET analysis, the numerical calculation becomes unstably, especially in the mesh containing quite small sodium mass. Therefore, it is necessary to modify the computational algorism to be stable and obtain the optimum value of K in sodium-water reactions.