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Sugawara, Takanori; Kunieda, Satoshi
Proceedings of International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2023) (Internet), 7 Pages, 2023/08
This study investigates the impact of the change from JENDL-4 to JENDL-5 on neutronics analysis of transmutation systems. As the transmutation systems, the following two systems are targeted: JAEA-ADS, a lead-bismuth cooled accelerator-driven system, and MARDS, a molten salt chloride accelerator-driven system. For the JAEA-ADS, the k-eff value increased 189 pcm from JENDL-4 to JENDL-5. It was found that the revisions of various nuclides affected to this difference. For example, the revision of 
N indicated an increase of 200 pcm from the JENDL-4 result. For the MARDS, it was found that the major revision of 
Cl and 
Cl cross sections was the main cause of the k-eff differences. This study confirmed that the difference in the nuclear data libraries still indicated differences in calculation results for the transmutation systems.
Kondo, Ryoichi; Nagaya, Yasunobu
Proceedings of International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2023) (Internet), 10 Pages, 2023/08
A functional expansion tally (FET) method with numerical basis functions generated by singular value decomposition (SVD) is newly proposed. Traditionally, analytical functions were used for the FET calculations, e.g., Legendre polynomials for a one-dimensional distribution. However, the expansion terms could increase to reconstruct steep or complex distributions with these functions. A basis set that can well represent the target distribution with lower order expansion is desired to achieve high accuracy with the small computational resource. In the present study, a numerical basis set is generated from snapshot data by using SVD. This approach is based on the reduced order modeling (ROM). We applied ROM to the FET method in Monte Carlo calculations. The numerical result showed the applicability of the proposed method, on the other hand, some issues were revealed, e.g., discretization of the snapshot data.