VERIFICATION OF DESIGN LEAKAGE RATES FOR ACTIVITY RELEASE CALCULATION

The mechanical and thermal loadings associated with the routine, normal and accident conditions of transport can have a significant effect on the leak tightness of the sealing system of transport casks for spent fuel and high radioactive waste. Applicants are requested by BAM to provide test programmes for verification of design leakage rates of the sealing system under the possible loads. Two test series initiated to clarify the dependency of the standard leakage rate on dynamic lid displacement as well as the dependency of the useful elastic recovery ru of a metallic seal on temperature and time, are outlined in this paper as examples of present investigations: Sliding tests simulating a lid displacement possible by a horizontal drop of the cask are carried out at the controlled drop test facility of BAM with test flange pairs equipped with metallic Helicoflex seals. For specification of covering values for the useful elastic recovery ru GNS has started a very comprehensive test programme with overall 70 metallic seals installed in test flanges which are stored for a period of one year at three different temperatures up to 150°C. This paper gives an overview about the current approach of BAM in the assessment of cask tightness and informs about the status of the running test series.