Material cross-sections real-time inversion from neutron detector data for nuclear reactor digital twin

Abstract

The Nuclear Reactor Digital Twin (NRDT) has garnered significant attention in recent years. One of the crucial aspects in NRDT is the real-time inversion of nuclear reactor core material cross-sections during reactor operation. In general, an inverse problem is solved by combining multiple iterations of the forward problem with an optimization algorithm. Even though the development of a surrogate model has significantly enhanced the computational efficiency of forward problems, the iteration process still poses a challenge to real-time inversion. To address this problem, this paper presents a real-time inverse problem solver (RIPS). During the offline stage, RIPS establishes a mapping between the sparse neutron detector data and the cross-sections through the reduced-order model and radial basis function. During the online stage, the corresponding cross-section can be calculated directly using the mapping and neutron detector data. Since the RIPS eliminates the multiple iterations of traditional methods, the efficiency of RIPS can be improved by orders of magnitude, and enables real-time online calculation. Three typical numerical benchmarks are tested for verification in this paper, which proves that the maximum relative error of RIPS does not exceed 0.54 % and the average relative error does not exceed 0.1986 %. Furthermore, for each test case, the calculation time of RIPS is within 0.01 s. This work can provide useful suggestions and applications, and further development in cross-section inversion.