Features of modelling of processes in spent fuel pools using various system codes

• We have modelled cooling water volume decrease events in the spent fuel pools.
• Identified possible unrealistic parameter values, trends and modelling errors.
• Recommendations for modelling of processes in spent fuel pools are presented.

Severe accidents have not yet occurred in spent fuel pools, however, the consequences can be very severe and a big amount of radioactive material can be released to the environment. Thus, the modelling of possible accidents using computer codes and analysis of consequences is very important. This paper presents results of modelling of cooling water volume decrease events in the spent fuel pools using four different system codes RELAP5, RELAP/SCDAPSIM, ATHLET-CD and ASTEC. The work is aimed to identify possible unrealistic fuel storage pool parameter states, trends and values and to assess the possible errors caused as a result. The influence of the selected modelling assumptions, approximations and impact of the structure of the models on the substantial nuclear fuel storage pools parameters during the beyond design basis accident were investigated.