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A two-step approach is proposed to accomplish high-fidelity whole-core resonance self-shielding calculation. Direct slowing-down equation solving based on the pin-cell scale is performed as the first step to simulate different operating conditions of the reactor. Resonance database is fitted using the results from the pin-cell calculation. Several techniques are used in the generation of the resonance database to estimate multiple types of resonance effects. The second step is the calculation of practical whole-core problem using the resonance database obtained from the first step. The transport solver is embedded both at the first step and the second step to establish the equivalence relationship between the fuel rod in the practical problem and the pin-cell at the first step. The numerical results show that the new approach have capability to perform high-fidelity resonance calculations for practical problem.

The high-fidelity reactor physics calculation attracts a lot of attention because of the development of high performance computing technology and increasing requirement of reducing the approximation of traditional methods. Here introduces a new high-fidelity deterministic neutronics code NECP-X being developed at Nuclear Engineering Computational Physics (NECP) lab at Xi’an Jiaotong University. Compared to previous developed codes like DeCART, MPACT and nTRACER, it has its own separate features such as a pseudo-resonant-nuclide subgroup method, a new free-matrix CMFD acceleration method and an axial S N solver for improving accuracy, etc. The VERA progression problems 1 through 5-2D are tested to verify NECP-X, and the numerical results show that NECP-X can obtain accurate results for all of this verification problems. [ABSTRACT FROM AUTHOR]

The development and verification of a coupling code system named NECP-X/SUBSC which integrates a high-fidelity neutronics code NECP-X and a thermal-hydraulics (T/H) subchannel code SUBSC are presented. In order to accomplish high-fidelity, improved and realistic geometry modeling such as semi-explicit representation of grid spacer, resonance self-shielding treatment with pseudo-resonant-nuclide subgroup method, anisotropic scattering treatments and 2D/1D fusion method are implemented in the NECP-X code. A group of benchmark problems, including VERA core physics benchmark progression problems 2–3, are utilized to verify NECP-X. A sub-channel code SUBSC is developed for the pin-by-pin thermal-hydraulics calculation. The high-quality experimental data provided by the OECD/NRC PWR Subchannel and Bundle Tests (PSBT) benchmark is used to validate SUBSC. After assessing the two separate codes, an internal coupling method is used to integrate SUSBC with NECP-X. Finally, the coupling code system NECP-X/SUBSC is applied to the VERA core physics benchmark problem #6, 3D Hot Full Power (HFP) assembly. Axial normalized pin power shapes for the pin with the highest power and the pin at the assembly corner, subchannel exit coolant temperature and volume averaged fuel pin temperatures at the axial level of maximum temperature are compared to results from the Consortium for Advanced Simulation of Light Water Reactor (CASL)’s MPACT/CTF code. [ABSTRACT FROM AUTHOR]

• The depletion capability of NECP-X is developed and validated in this work. The depletion capability of NECP-X is developed. Two depletion libraries are developed for depletion calculations. One full-fidelity depletion library contains 1547 isotopes, and a new compressed depletion library is generated. Cross sections from the EAF-2010 library are integrated into depletion libraries, which give cross sections for reaction channels not included in the ENDF library. For the traditional predictor-corrector method, two transport calculations are conducted during every depletion step, where transport calculation is very time consuming, so a new transport-depletion coupling strategy is developed to reduce calculation time. The VERA depletion benchmark problems are utilized to assess the accuracy of compressed depletion library and new coupling method. The equivalent pin-cell model and assembly model, which are often used for validation, are asserted by comparing to the full-core model. Finally, measurement data for 22 fuel samples are used to validate the depletion capability of NECP-X. The results demonstrate good accuracy of NECP-X. [ABSTRACT FROM AUTHOR]