| Abstract Scope |
In-core neutron testing is the primary method for evaluating next-generation nuclear materials; however, it is expensive, time-consuming, and produces radioactive byproducts. Dual-beam ion irradiations present an attractive, lower-cost alternative combining displacement damage and simultaneous gas injection to mimic transmutation. A critical aspect in matching neutron irradiation effects with ions is the helium-to-displacements-per-atom (He/dpa) ratio. Defining a functional range of He/dpa values is essential for establishing experimental test conditions but proves difficult due to currently existing computational discrepancies. Although neutronics and inventory programs, like FISPACT-II, can calculate these ratios, the results are susceptible to variables such as nuclear data library selection, flux spectrum accuracy, computational methods, and alloy composition, making it challenging to define a reliable He/dpa range for experimental reporting and design. To overcome this, we developed F-SCATTER, a Python program wrapped around FISPACT-II. F-SCATTER simulates compositional and spectral uncertainty over thousands of iterations of experimental conditions, providing a comprehensive table of potential He/dpa values in relevant alloys and spectra. When applied to HT9 steel irradiated in the FFTF fast neutron spectrum, F-SCATTER identified major sources of variation: 107% deviation in He/dpa from alloy composition, 75% from computational method, and 260% from nuclear data library choice, with spectral uncertainty accounting for a minor 3% deviation. We also found, through alloy sensitivity analysis, that a linear relationship exists between nitrogen content and He/dpa, providing insights into future HT9 composition optimization. Additional reference cases for common structural materials in thermal and fusion spectra will be reported as part of this presentation. |