103.1
Nuclear Safety Research: a GRS Perspective
Uwe Stoll
Gesellschaft für Anlagen- und Reaktorsicherheit gGmbH Boltzmannstr. 14
85748 Garching bei München , Germany uwe.stoll@grs.de
ABSTRACT
Major reactor accidents such in Japan 2011 tend to shift reactor safety programmes toward low-probability, high-consequence scenarios and rare phenomena associated with core melt. One reason for this is that closing knowledge gaps in severe accident behaviour and adding (mitigative) safety features is widely perceived as an effective approach to increase safety. Although important, this approach has somehow put back the fact that there are also operational effects not sufficiently understood or analysed such as increased corrosion of fuel rod cladding, neutron flux fluctuations in PWRs and fuel assembly bowing. Germany’s central Technical Support Organisation GRS has made sure that in its reactor safety research programme both is addressed appropriately: (severe) accident related topics and operational issues. The presentation addresses the current research status of the aforementioned operational issues and points out further work to be done in these fields. In addition, two examples of research activities concerning accidents are discussed. One is the estimation of radioactive materials releases during severe accidents in the spent fuel pool. The results gained from this analysis can be used e.g. for the Fast Source Term Prognosis tool FaSTPro developed by GRS for decision-making during emergency situations. Another topic described in the presentation is a new method of statistical assessment of loss-of-coolant accidents, answering a recommendation of the German Reactor Safety Commission.