NUMERICAL STUDY OF THE THERMAL BEHAVIOUR OF PACKAGES SUBJECTED TO FIRES OF LONG DURATION

The purpose of this study is to improve the knowledge of the behaviour of type B packages used for the transportation of radioactive materials, when subjected to fires of long duration and at different flame temperatures, and to evaluate the safety margins when performances are compared to regulatory requirements. This paper outlines the approach and the results obtained in the specific case of the FS 47 package. Firstly, a long duration fire test has been performed in 1993 upon request of IPSN and competent authorities. The fire lasted 3 h 25 min without loss of the leak tightness of the full- , scale tested package. Secondly, an experimental simulation bas been performed in a laboratory to simulate with a sample the thermal behaviour of confined plaster. Thirdly, specific behaviour simulation laws were incorporated in the selected Finite Element (FE) code TIIER.MX and their validation was performed by comparison with the results of the long duration FS 4 7 fire test. Fourthly, the proper sensitivity study with respect to the duration and temperature of fire is being carried out. Hence, it was possible to evaluate the performance of the package and to determine its limit of resistance for different fire conditions.