Initial Thermal Testing of the Pipe Over-Pack Container With a Combustible Waste Matrix for 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 Pipe Over-pack Container (POC) is a vented carbon steel container with a removable lid designed for storing or transferring nuclear waste. Additionally, 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. Conducting thermal testing with a combustible waste matrix in the POC can benefit stakeholders on increasing the material limits of the container. The results of these measurements will establish new wattage limits to meet LANL’s 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. Combustible loading consisted of an arrangement of cellulosics, plastics, rubber and other contents such as tape. An initial arbitrary limit was set at 60 °C reflecting previous research on nitrate contaminated cheesecloth within a combustible loaded matrix. The limit will ensure the sensitivity of nitrate contaminated contents is undisturbed. Two tests were conducted on the waste matrix at 9.3 watts and 15 watts payloads. Each test was conducted within an 8 hour work day while observing the transient response to ensure the testing does not exceed the temperature limit. Results show that with a 15 watt payload the temperature at the source reaches the 60 °C limit within 5 hours of testing. Other areas such as the cheesecloth and plywood are under the arbitrary limit. Observations and pictures showed no signs of material degradation from heat loading which allow us to move past the limit and investigate higher payloads. ANSYS numerical modeling has complemented the efforts by producing predictions within 5% error of experimental results. These results along with previous POC thermal testing will be presented to the Packaging and Transportation (OS-PT) group at LANL to assist in raising the heat source plutonium loading limit.