Steady-State Thermal Analysis of the Pipe Overpack Container for Transuranic Waste at Los Alamos National Laboratory

Los Alamos National Laboratory (LANL) Technical Area 55 (TA 55) utilizes several different container types to store and transfer special nuclear material and waste for numerous programs. The Nuclear Process Infrastructure Infrastructure Operations Group (NPI-2) analyzes and certifies containers to meet the specifications for distinct processes and storage. Engineering analyses performed on these containers include but are not limited to: leak testing, filter efficiency testing, pressure drop test, drop testing, water penetration testing, polymer (Oring) hardness testing, and thermal steady-state testing. Of all of these tests, thermal steady-state testing is most crucial to ensure critical components for specific containers do not fail under an internal heat payload. This testing provides data for setting heat payload limits for different containers. TA 55 has been tasked to manage and store all of its Transuranic (TRU) waste for the foreseeable future. Being able to place more material into a single container conserves the physical storage space available at TA 55. The Pipe Overpack Container (POC) is a vented carbon steel container with a removable lid designed for storing or transferring nuclear waste. The POC Handling and Operations Manual requires each user to ensure that the maximum temperature of each component is not exceeded. Conducting a thermal steady-state test on the POC can benefit stakeholders in increasing the material limits of the container. The POC was loaded with sealed Plutonium (Pu-238) heat sources in a controlled laboratory environment. Thermistors attached were used to measure temperature behavior. The results of these measurements will establish new wattage limits to meet LANLs transportation requirements. The current LANL Transportation Safety Document (TSD) limits the amount of heat source plutonium to 10 grams per POC, corresponding to approximately 5 watts of heat. The result of this test was provided to the Packaging and Transportation (OS?PT) group to evaluate new wattage limits that can satisfy the needs of TA 55, while maintaining a safe packaging configuration.