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India’s PFBR attains criticality at last
Prime Minister Narendra Modi proclaimed it “a proud moment for India” when on April 6 the 500-MWe, sodium-cooled Prototype Fast Breeder Reactor (PFBR) achieved initial criticality. This milestone, which comes some 22 years after the continually delayed PFBR project began, marks India’s entrance into the second stage of its three-stage nuclear program, which has the ultimate goal of supporting the country’s nuclear power program with its significant thorium reserves.
Marco Tiberga, Simone Santandrea
Nuclear Science and Engineering | Volume 198 | Number 4 | April 2024 | Pages 853-897
Research Article | doi.org/10.1080/00295639.2023.2214488
Articles are hosted by Taylor and Francis Online.
The development of higher-order method of characteristics (MOC) discretizations has become of great interest to improve the performance of solvers based on the standard Stepwise Constant (SC) MOC approximation. Many codes nowadays implement a Stepwise Linear (SL) volume flux approximation or diamond differencing schemes. In the multigroup lattice solver TDT of the industrial code APOLLO3®, developed at CEA, a Linear Surface (LS) scheme was implemented. In this method, the flux is reconstructed from a linear interpolation made from surface values, therefore ensuring a similar spatial linear development but with a lower computational cost than the volume-based approximations. However, the LS-MOC scheme can conserve only the constant spatial moment of the flux. To overcome this limitation, in this paper we propose an improved version of the LS scheme called LS- able to preserve the linear spatial moments of the flux. Compared to the other high-order volume-based approximations, the LS- scheme also preserves flux surface moments, which guarantees higher accuracy. Moreover, our scheme has a lower memory footprint because it does not require the storage of response matrices that are dependent on region, group, and anisotropy order. Tests carried out on severe rodded assembly cases show the superior performance of the proposed method with respect to not only the classic SC or LS MOC scheme but also the SL scheme.