MATHEMATICAL MODEL OF THE NPP KRŠKO PCFV SYSTEM FOR THE RELAP5 COMPUTER CODE

Containment building is the final barrier for radioactive releases from a nuclear power plant (NPP). Preserving its integrity will minimize these releases even in a case of a severe accident with core degradation and melt discharge in the containment accompanied with the pressure and temperature increase. Installation of a venting system with ability to filter radioactive fission products is a preferred way to deal with the issue in present and future NPPs, especially after the Fukushima accident. Such system, called passive containment filtered venting system (PCFV), was installed in 2013 in the NPP Krško. Thermal hydraulic model of the PCFV system which included aerosol and iodine filters, associated pipings and valves was developed for the best-estimate computer code RELAP5. Main results and discussion are presented and compared with relevant plant documentation