Multiphysics Modeling and Validation of Spent Fuel Isotopics Using Coupled Neutronics/Thermal-Hydraulics Simulations

Dean Price,Majdi I Radaideh,Travis Mui,Tomasz Kozlowski,Mihir Katare

doi:10.1155/2020/2764634

Dean Price, Majdi I Radaideh + Show 3 more

Open Access

https://doi.org/10.1155/2020/2764634

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Abstract

Multiphysics coupling of neutronics/thermal-hydraulics models is essential for accurate modeling of nuclear reactor systems with physics feedback. In this work, SCALE/TRACE coupling is used for neutronic analysis and spent fuel validation of BWR assemblies, which have strong coolant feedback. 3D axial power profiles with coolant feedback are captured in these advanced simulations. The methodology is applied to two BWR assemblies (2F2DN23/SF98 and 2F2D1/F6), discharged from the Fukushima Daini-2 unit. Coupling is performed externally, where the SCALE/T5-DEPL module transfers axial power data in all axial nodes to TRACE, which in turn calculates the coolant density and temperature for each of these nodes. Within a burnup step, the data exchange process is repeated until convergence of all coupling parameters (axial power, coolant density, and coolant temperature) is observed. Analysis of axial power, criticality, and coolant properties at the assembly level is used to verify the coupling process. The 2F2D1/F6 benchmark seems to have insignificant void feedback compared to 2F2DN23/SF98 case, which experiences large power changes during operation. Spent fuel isotopic data are used to validate the coupling methodology, which demonstrated good results for uranium isotopes and satisfactory results for other actinides. This work has a major challenge of lack of documented data to build the coupled models (boundary conditions, control rod history, spatial location in the core, etc.), which encourages more advanced methods to approximate such missing data to achieve better modeling and simulation results.

Highlights

Neutronics and thermal-hydraulics coupling involves exchanging data on axial power distribution and coolant characteristics across physics codes [12]. is process can be done with external coupling [13], which is the method used in this study for validation of spent fuel isotopic composition
Verification of the coupling process is performed by analyzing the convergence and axial power behavior at the assembly level
Multiphysics coupling of SCALE/TRACE is used in this work for neutronic analysis and spent fuel validation of boiling water reactors (BWRs) spent fuel isotopics. e coupling is performed externally where SCALE/T5-DEPL module sends axial power profile to TRACE, which returns coolant density and temperature. is process is repeated until convergence of all quantities at each time step

Summary

Introduction

For BWRs, even with reported experimental data, major assumptions were needed to be made about the behavior of axial coolant density distributions in order to create verification models in [4]. Such assumptions can introduce uncertainties in the calculations because void fraction feedback is not captured [5, 6]. E current study seeks to avoid this difficulty by coupling the thermal-hydraulics code TRACE to the T5DEPL depletion sequence in SCALE for validation of spent fuel composition, thereby avoiding the need for detailed history of void distribution data.

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