Extending Periodic Leakage Rate Testing of 9977 Packages With Elastomeric O-Rings

According to ANSI N14.5, the periodic leakage rate testing of Type B radioactive material transportation packages is performed within 12 months prior to each shipment. The purpose of performing periodic leakage rate testing is to confirm that packages built to an approved design can perform their containment function as required after a period of use. However, certain transportation packages, e.g., Model 9975 and 9977 Type B packages, have been used for interim storage for a period > 12 months, and it is desirable to extend the periodic leakage rate testing interval to reduce personnel radiation exposure and cost. Long-term leak performance tests on O-ring test fixtures have been conducted at 200°F (366K) and higher temperatures since 2004 for the purpose of interim storage of 9975 packages. The test data are adopted and evaluated in this paper by using the Arrhenius function and the Weibull statistics to establish the basis for extending the periodic leakage rate testing interval. The results show that the testing interval can be extended to 5 and 2 years for Model 9977 packages with Viton^® GLT and GLT-S elastomeric O-rings (Parker Seals V0835-75 and VM835-75), respectively, if the O-ring service temperature is kept below 200°F (366K) and verified with continuous temperature monitoring.