Multi-physics Sub-pin Resolution Analysis of a PWR core with nTRACER/CTF for the OECD/NEA TVA Watts Bar 1 Benchmark

The systematic use of high-fidelity high-resolution codes which allow the prediction of safety parameters on a local scale, can result in more efficient use of the nuclear fuel and of the nuclear reactor.The Laboratory of Reactor Physics and Thermal-Hydraulics of PSI is developing a high-resolution multi-physics tool with the neutronic code nTRACER and the sub-channel code COBRA-TF (CTF) for PWR full core analysis.This work presents the verification of nTRACER with Serpent2 reference solutions within the framework of the OECD/NEA TVA Watts Bar 1 benchmark.The nTRACER results indicate good agreement with the Serpent2 predictions for the initial criticality case of TVA WB1.The maximum axially averaged pin power difference is 1.08%.nTRACER is also verified with the benchmark Exercise 1-Hot Zero Power start-up tests, never exceeding 100 pcm of difference with Serpent2.In addition, the coupled code system nTRACER/CTF is compared with the MC21/CTF reference solution for the Hot Full Power Exercise 2 of the benchmark.nTRACER/CTF presents good agreement in terms of assembly and eigenvalue.The maximum power difference is 1.54%.The assembly outlet temperature is underestimated power by a maximum of 2.66 °C.This can be attributed to different modeling options and material properties used by nTRACER/CTF and the reference solution.