The AP1000® advanced Pressurized Water Reactor (PWR) is designed and developed by Westinghouse Electric Company. The AP1000® safety approach and design are such that the plant is capable to mitigate all the Design Basis Accidents (DBAs) relying only on passive safety systems with no AC power and no or very limited operator action. In addition to the passive features, the active systems within the AP1000 design are classified as non-safety related systems, coherently with the fact that they are not needed in an accident scenario and that the plant is surely safe also postulating their failure following a DBA. The high standard against which these active systems are designed and the margin in the design, make the systems realistically available following a DBA and, hence, they could be used to mitigate the accident and improve plant recovery after the accident. A demonstration on how the Normal Residual Heat Removal System (RNS), an active non-safety related system, could be used to mitigate a DBA is given in this paper. The selected accident is the inadvertent actuation of the Automatic Depressurization System (ADS) initially occurring with the plant operating at full power. Relap5 is a computer code well adapted to analyzing this event. Relap5 simulations of the accident, performed on a suitable detailed model of the AP1000® developed in Ansaldo Nucleare S.p.A., demonstrate that RNS can actually be used to reduce the impact of this accident on the containment, hence improving plant recovery after the accident.
AP1000 Recovery Improvement After ADS Inadvertent Actuation
AMBROSINI, WALTER
2012-01-01
Abstract
The AP1000® advanced Pressurized Water Reactor (PWR) is designed and developed by Westinghouse Electric Company. The AP1000® safety approach and design are such that the plant is capable to mitigate all the Design Basis Accidents (DBAs) relying only on passive safety systems with no AC power and no or very limited operator action. In addition to the passive features, the active systems within the AP1000 design are classified as non-safety related systems, coherently with the fact that they are not needed in an accident scenario and that the plant is surely safe also postulating their failure following a DBA. The high standard against which these active systems are designed and the margin in the design, make the systems realistically available following a DBA and, hence, they could be used to mitigate the accident and improve plant recovery after the accident. A demonstration on how the Normal Residual Heat Removal System (RNS), an active non-safety related system, could be used to mitigate a DBA is given in this paper. The selected accident is the inadvertent actuation of the Automatic Depressurization System (ADS) initially occurring with the plant operating at full power. Relap5 is a computer code well adapted to analyzing this event. Relap5 simulations of the accident, performed on a suitable detailed model of the AP1000® developed in Ansaldo Nucleare S.p.A., demonstrate that RNS can actually be used to reduce the impact of this accident on the containment, hence improving plant recovery after the accident.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
