Sump clogging has been identified as a relevant issue after an accident occurred in the Barsebäck 2 nuclear power plant in Sweden (1992). Following a steam line Loss of Coolant Accident (LOCA), due to an inadvertent opening of a safety relief valve, the je t stripped some insulation material from nearby pipes. The insulation debris were transported to the inlet of the strainers for the drywell spray system, clogging the intake. The accident was not serious, but it showed that the Emergency Core Cooling Syste m (ECCS) could have failed. As a consequence several actions have been undertaken by international organizations, regulatory bodies and nuclear power plant owners to characterize this issue and propose solutions and improvements to the plants. In the pre sent paper, the Reliability Evaluation of Passive Safety System (REPAS) methodology is applied for characterizing the sump clogging issue in case of long term core cooling. O riginally developed to evaluate the reliability of passive systems REPAS is here applied to an active system. The application is performed using the TRAC/RELAP Advanced Computational Engine (TRACE) code, developed by USNRC, to simulate a generic three loops PWR, considering an active Decay Heat Removal System (DHR).
Methodology and Application to Characterize the Sump Clogging Issue in case of Long Term Core Cooling
D’Auria Francesco
Methodology
;
2021-01-01
Abstract
Sump clogging has been identified as a relevant issue after an accident occurred in the Barsebäck 2 nuclear power plant in Sweden (1992). Following a steam line Loss of Coolant Accident (LOCA), due to an inadvertent opening of a safety relief valve, the je t stripped some insulation material from nearby pipes. The insulation debris were transported to the inlet of the strainers for the drywell spray system, clogging the intake. The accident was not serious, but it showed that the Emergency Core Cooling Syste m (ECCS) could have failed. As a consequence several actions have been undertaken by international organizations, regulatory bodies and nuclear power plant owners to characterize this issue and propose solutions and improvements to the plants. In the pre sent paper, the Reliability Evaluation of Passive Safety System (REPAS) methodology is applied for characterizing the sump clogging issue in case of long term core cooling. O riginally developed to evaluate the reliability of passive systems REPAS is here applied to an active system. The application is performed using the TRAC/RELAP Advanced Computational Engine (TRACE) code, developed by USNRC, to simulate a generic three loops PWR, considering an active Decay Heat Removal System (DHR).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
