Coupling of ASTEC 2.1.1.6 and RASCAL 4.3 Codes to Evaluate the Source Term and the Radiological Consequences of a Loss-of-Cooling Accident at a Spent Fuel Pool

This paper deals with a general methodology to evaluate the Source Term (ST) and the Radiological Consequences (RC) of a Severe Accident (SA) at a Fukushima-like Spent Fuel Pool (SFP) by coupling ASTEC 2.1 and RASCAL 4.3 codes. Essentially, the ST provided by ASTEC is used as input to RASCAL to perform a RC analysis. This methodology was developed as a preparatory study for the Management and Uncertainties in Severe Accident (MUSA) H2020 European Project, coordinated by CIEMAT. Within MUSA project, the laboratory for the Safety of Nuclear Installation of ENEA is involved in the Innovative Management of SFP Accidents Work Package (WP6), coordinates by IRSN. Within WP6, ENEA is committed to perform an analysis on a Fukushima-like SFP with the aim to apply innovative measures on the SFP Severe Accident Management to mitigate the RC of the accident itself. In order to perform the RC studies, the Fukushima-like SFP has been assumed located in one of the Italian cross-border NPP sites. The weather data connected with the radionuclides transport in atmosphere phase are both standard and real hourly meteorological data. The results of the RC for 96 hours of ST release from the SFP in a range of 160 km from the emission point are reported in terms of Total Effective Dose Equivalent (TEDE), I-131 thyroid dose and Cs-137 total ground deposition. The mitigating effect on ST and on RC of the cooling spray system (CSS) actuated with several pH values (i.e., 4,7,10) was also investigated.