Solution of the BEAVRS benchmark using the nTRACER direct whole core calculation code

TLDR

The study solves the BEAVRS benchmark with the nTRACER whole‑core code to evaluate its accuracy and sensitivity to modeling parameters. A detailed nTRACER core model, refined through sensitivity studies, is used to compute hot‑zero‑power states and depletion for two cycles, with results compared to Monte Carlo solutions (McCARD and OpenMC) and experimental data such as control‑rod worths, in‑core detector signals, and boron concentrations. The computed criticality, control‑rod bank worths, and boron‑let‑down curves agree with measurements within 180 pcm and 25 ppm, confirming the model’s accuracy.

Abstract

The BEAVRS (Benchmark for Evaluation and Validation of Reactor Simulation) benchmark is solved by the nTRACER direct whole core calculation code to assess its accuracy and to examine the solution dependence on modeling parameters. A sophisticated nTRACER core model representing the BEAVRS core is prepared after a series of sensitivity study to ensure solution accuracy. The resulting solutions for several hot-zero-power (HZP) states are compared first with the corresponding Monte Carlo solutions, which consist of the McCARD solutions for the assembly problems and the OpenMC solutions for the core problems, and then with the measured data which include the control rod worths (CRWs) and incore detector signals as well as the critical boron concentrations (CBC). The core depletion calculation is performed for the initial and second cycles with a set of approximated power histories and the calculated CBCs are compared with the measured data. The comparison results show that the criticality, control rod bank worths at HZP and the boron let-down curves of two cycles agree well with the measurements within 180 pcm and 25 ppm, respectively.