ORNL Special Form Testing of Sealed-Source Encapsulations
In the United States of America all transportation of radioactive material is regulated by the Department of Transportation (DOT), along with input from the Nuclear Regulatory Commission. Beginning in 2008 a new type of sealed-source encapsulation package was developed at Oak Ridge National Laboratory (ORNL); these packages contain radioactive material and are regulated and transported in accordance with the requirements set for DOT Class 7 hazardous material. DOT provides regulations pertaining to specific package contents categorized as special form designs. The special form designation indicates that the encapsulated radioactive contents have a very low probability of dispersion even when subjected to significant structural conditions. All ORNL DOT designs have been certified by DOT as being special form materials. The special form designs have been shown to simplify the delivery, transport, acceptance, and receipt process. Simplification of the transportation process makes the sealed-source encapsulation designs very advantageous for shipment to various facilities throughout the lifetime of the special form material. To this end, DOT Certificates of Competent Authority (CoCAs) have been sought for the design suitable for containing high-alpha-activity actinide materials. This design consists of a core of porous zirconia matrix pre-encapsulated within triangular canister (ZipCan) tiles that are then enclosed by a spherical shell. This new ZipCan design and a similar rectangular ZipCube design were tested for compliance with the regulations found in Title 49, Code of Federal Regulations, Section 173.469, Tests for Special Form Class 7 (Radioactive) (49 CFR 173.469) materials. The spherical enclosure was subjected to 9 m impact, 1 m percussion, and 10-minute thermal tests. Before and after each test the designs were subjected to a helium leak check and a bubble test. The ZipCan tiles and core were subjected to the tests required for ISO 2919:1999(E), including a Class 4 impact test and heat test, and were subsequently subjected to helium leakage rate tests [49 CFR 173.469(a)(4)(i)]. The impact tile test unit contained a nonradioactive surrogate; however, the thermal test unit contained a radioactive source. All three designs are still undergoing regulatory special form testing, and all three sealed-source encapsulation designs are to be submitted to DOT for CoCAs.