A neutronics investigation simulating fast reactor environments in the thermal-spectrum advanced test reactor

Developing advanced fuel and materials for fast-spectrum nuclear reactors is an immense challenge with tremendous potential in maximizing the value of advanced nuclear reactors. Historical developments and modern materials show promise for overcoming these challenges, but the lack of fast neutron test capabilities in the United States is a significant obstacle for meaningful progress. Modern modeling techniques were utilized to investigate a proposed method for fast neutron irradiations in an existing thermal-spectrum reactor, the Advanced Test Reactor (ATR). This method builds upon past ideas, where fast flux is increased by surrounding the specimens with fissionable “booster fuel” but diverges from historical approaches by using an already developed fuel element design used in the Belgian Reactor 2 (BR2) as the booster fuel while leveraging modern 3-D modeling and simulation techniques. Design evaluations and neutronics predictions were performed to evaluate the performance of a BR2 fuel element irradiated in an ATR flux trap with test pins in the central channel of the BR2 fuel element. These efforts have yielded promising results.