NEUTRONIC MODELLING OF THE FFTF CONTROL ROD WORTH MEASUREMENTS WITH DIFFUSION CODES

E Nikitin,K Mikityuk,E Fridman,C Fiorina,S Radman

doi:10.1051/epjconf/202124710017

Abstract

This paper presents an assessment of three deterministic core simulators with the focus on the neutronic performance in steady-state calculations of small Sodium cooled Fast Reactor cores. The selected codes are DYN3D, PARCS and the novel multi-physics solver GeN-Foam. By using these codes, the multi-group diffusion solutions are obtained for the selected twenty control rod worth measurements performed during the isothermal physics tests of the Fast Flux Test Facility (FFTF). The identical set of homogenized few-group cross sections applied in the calculations is generated with the Serpent Monte Carlo code. The numerical results are compared with each other as well as with the measured values. The obtained numerical results, such as the multiplication factors and control rod worth values, are in good agreement as compared to the experimental data. Furthermore, a comparison of the radial power distributions is presented between DYN3D, PARCS and GeN-Foam. Ultimately, the power distributions are compared to the full core Serpent solution, demonstrating an adequate performance of the selected deterministic tools. In overall, this study presents a verification and validation of the neutronic solvers applied by DYN3D, PARCS and GeN-Foam to steady-state calculations of SFR cores.

Highlights

This paper presents a study to verify and validate three neutron diffusion solvers for steady-state calculations of small Sodium cooled Fast Reactor (SFR) cores
The diffusion solvers of DYN3D are based on the nodal expansion methods (NEM)
The ones that are suitable for SFR calculations, as they are derived for hexagonal-z geometry, form the family of HEXNEM solvers

Summary

INTRODUCTION

This paper presents a study to verify and validate three neutron diffusion solvers for steady-state calculations of small Sodium cooled Fast Reactor (SFR) cores. These solvers are part of the foundation of three reactor core simulators: DYN3D [1], PARCS [2] and GeN-Foam [3]. The hexagonal solver of PARCS is based on NEM, in contrast to HEXNEM, it divides the hexagons into six triangles and employs polynomial expansion of the fluxes for each triangular node This solver is called the Trianglebased Polynomial Expansion Nodal (TPEN) method.

DESCRIPTION OF THE BENCHMARK

Homogenized Multi-Group Cross Sections

Selected Tests

Control Rod Worth Calculations

Code-to-Code Comparison in Reference Critical State