[en] This paper describes a risk-based screening analysis that was performed on the Surry nuclear power station to evaluate the adequacy of technical specifications (TS) for PWRs during shutdown periods. Of particular concern was the risk sensitivity to allowable TS configurations while at reduced reactor coolant system inventory conditions since incidents have occurred in plants over recent years during this time. A typical refueling outage was analyzed to determine the plant configurations created due to surveillance testing and maintenance activities. The impact from single and multiple component outages were identified so their risk influence on the plant configuration could be assessed. From these results, generic insights into the efficiency of existing TS to control high risk configurations were obtained as well as the applicability and ability of the risk-based methodology employed to make that determination

[en] This paper describes a risk-based screening analysis that was performed on the Surry nuclear power station to evaluate the adequacy of technical specifications (TS) for the PWRs during shutdown periods. Of particular concern was the risk sensitivity to allowable TS configurations while at reduced reactor coolant system inventory conditions since incidents have occurred in plants over recent years during this time. A typical refueling outage was analyzed to determine the plant configurations created due to surveillance testing and maintenance activities. The impact from single and multiple component outages were identified so their risk influence on the plant configuration could be assessed. From these results, generic insights into the efficiency of existing TS to control high risk configurations were obtained as well as the applicability and ability of the risk-based methodology employed to make the determination

[en] An iron-free, low-energy charged-particle magnetic spectrometer is designed using a Helmholtz-coil geometry. Through the fringe fields of the coils, the spectrometer provides focusing in both the dispersive and non-dispersive planes. By choosing the optimal deflecting angle and the positions of the source and the focal distance, we expect to obtain a momentum resolution of the order of 0.3%

[en] Emergency Diesel Generators (EDGs) provide on-site emergency alternating current (ac) electric power for a nuclear plant in the event that all off-site power sources are lost. Existing regulations establish requirements for designing and testing of these on-site power sources to reduce to an acceptable level the probability of losing all ac power sources. Operating experience with EDGs has raised questions about their testing and maintenance to achieve the EDG reliability levels and the total EDG unavailability experienced (fraction of time EDG is out-of-service due to testing, maintenance, and failures). In this report, recent operating experience is used to assess EDG unavailability due to testing, maintenance, and failures during reactor power operation and during plant shutdown. Recent data show an improvement in EDG reliability, but an increase in EDG unavailability due to maintenance, a significant portion of which is due to routinely scheduled maintenances. Probabilistic safety assessments (PSAs) of selected nuclear power plants are used to assess the risk impact of EDG unavailability due to maintenance and failure during power operation, and during different stages of plant shutdown. The results of these risk analyses suggest qualitative insights for scheduling EDG maintenance that will have minimal impact on risk of operating nuclear power plants