Problem - Dependent ORIGEN Library Compression to Increase Computational Efficiency

ORIGEN is a highly accurate code to model used fuel isotopic inventory evolution and associated radiation sources. The Oak Ridge Isotope Generation (ORIGEN) code is a depletion model to calculate neutron activation, actinide transmutation, fission product generation, and radiation source terms. This is done through analysis of the full isotopic transition matrix to solve the rate equations that describe the nuclide generation, depletion, and decay processes. This system tracks 2237 isotopes and 54331 transitions, making it the preeminent code for evaluating used nuclear fuel isotopic evolution and production in the world. A next-generation approach to using ORIGEN for accurate source term and depletion models is the direct incorporation of ORIGEN into larger frameworks that rely upon activation and depletion source terms via the modern ORIGEN Application Program Interface (API). However, many problems would benefit most from a reduction in the computational cost of directly performing depletion calculations via ORIGEN. The method to reduce computational cost presented in this paper relies on a lossy compression algorithm to reduce the ORIGEN reactor data library size. This is achieved by a reduction of the nuclides and transitions being tracked by elimination of nuclides and transitions unimportant for the specified problem, whether that is tracking decay heat, dose, or specific isotopic contents for depletion, resulting in a final library size of approximately 300-500 isotopes. These generated problem-specific libraries do not result in a significant sacrifice in accuracy by focusing on the determination of important contributing nuclides in a generalized manner such to enable reliable calculation of source terms without carrying the full transition matrix through the calculation. This method has been shown to potentially reduce run times and memory requirements by an order of magnitude.