Published: 2013
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There is currently no large-scale production of 238Pu in the United States. Feasibility studies were performed at the Idaho National Laboratory to assess the capability of developing alternative 238Pu production strategies. Initial investigations indicate potential capability to provision radioisotope-powered systems for future space exploration endeavors. For the short term production of 238Pu, sealed canisters of dilute 237Np solution in nitric acid could be irradiated in the Advanced Test Reactor (ATR). Targets in the large and medium "I" positions of the ATR were irradiated over a simulated period of 306 days and analyzed using MCNP5 and ORIGEN2.2. Approximately 0.5 kg of 238Pu could be produced annually in the ATR with purity greater than 92%. Optimization of the irradiation cycles could further increase the purity to greater than 98%. Whereas the typical purity of space batteries is between 80 to 85%, the higher purity 238Pu produced in the ATR could be blended with existing lower-purity inventory to produce useable material. Development of irradiation methods in the ATR provides the fastest alterative to restart United States 238Pu production. The analysis of 238Pu production in the ATR provides the technical basis for production using TRIGA® (Training, Research, Isotopes, General Atomics) nuclear reactors. Preliminary analyses envisage a production rate of approximately 0.7 kg annually using a single dedicated 5-MW TRIGA reactor with continuous flow loops to achieve high purity product. Two TRIGA reactors represent a robust means of providing at over 1 kg/yr of 238Pu annually using dilute solution targets of 237Np in nitric acid. Further collaboration and optimization of reactor design, radiochemical methods, and systems analyses would further increase annual 238Pu throughput, while reducing the currently evaluated reactor requirements.