Safety assessment and fire test on Type B packages of combustible thermal insulator for radioactive materials

From the test results about two Type-B packagings, it was found that the maximum temperatures sometimes appeared after more than three hours. These temperature rises may be caused by the combustion of thermal insulators. Inspite of these results, both Packaging 1 and 2 were proved to have enough ability to keep their integrity. It is desirable, however, to determine the fire safety according to the maximum temperatures of each internal containers. So, about packagings using combustible thermal insulators, we think it conservative and necessary to eliminate the provision which allows the artificial cooling after three hours. 2 references, 9 figures, 2 tables