Investigation of the safety features of advanced PWR assembly using SiC, Zr, FeCrAl and SS-310 as cladding materials

Sayed Saeed Mustafa

doi:10.1038/s41598-021-96954-9

Abstract

In this work, SiC (Silicon carbide), FeCrAl (ferritic), SS-310 (stainless steel 310) and Zirconium are simulated by MCNPX (Monte Carlo N‐Particle eXtended) code as cladding materials in advanced PWR (Pressurized Water Reactor) assembly. A number of reactor safety parameters are evaluated for the candidate cladding materials as reactivity, cycle length, radial power distribution of fuel pellet, reactivity coefficients, spectral hardening, peaking factor, thermal neutron fraction and delayed neutron fraction. The neutron economy presented by Zr and SiC models is analyzed through the burnup calculations on the unit cell and assembly levels. The study also provided the geometric conditions of all cladding materials under consideration in terms of the relation between fuel enrichment and cladding thickness from the viewpoint to achieve the same discharge burnup as the Zircaloy cladding. It was found that the SiC model participated in extending the life cycle by 2.23% compared to Zr. The materials other than SiC largely decreased discharge burnup in comparison with Zircaloy. Furthermore, the claddings with lower capture cross-sections (SiC and Zr) exhibit higher relative fission power at the pellet periphery. The simulation also showed that using SiC with a thickness of 571.15 μm and 4.83% U-235 can satisfy the EOL irradiation value as Zr. For reactivity coefficient, the higher absorbing materials (SS-310 and FeCrAl) exhibit more negative FTCs, MTCs and VRCs at the BOL But, at the intermediate stages of burnup Zr and SiC have a strong trend of negative reactivity coefficients. Finally, the delayed neutron fraction of SiC and Zr models is the highest among all the four models.

Highlights

In this work, silicon carbide (SiC) (Silicon carbide), ferritic iron chromium aluminum alloy (FeCrAl), SS-310 and Zirconium are simulated by MCNPX (Monte Carlo N‐Particle eXtended) code as cladding materials in advanced PWR (Pressurized Water Reactor) assembly
Because of the inherent resistance of Zirconium alloys to a variety of environmental conditions, they have been used effectively as cladding materials in light water reactors[1]. These alloys have many advantages as the excellent neutron economy and the small capture cross sections, their resistance to oxidation is reduced when subjected to high temperatures during the reactor operation
Silicon carbide compounds have many advantages, such as excellent high-temperature properties, good corrosion resistance, low neutron absorption cross-section and no absorption peak of hydrogen during normal operation, and a considerable life increase when the fuel is irradiated at high-burnup v alues[7]

Summary

Introduction

SiC (Silicon carbide), FeCrAl (ferritic), SS-310 (stainless steel 310) and Zirconium are simulated by MCNPX (Monte Carlo N‐Particle eXtended) code as cladding materials in advanced PWR (Pressurized Water Reactor) assembly. Because of the inherent resistance of Zirconium alloys to a variety of environmental conditions, they have been used effectively as cladding materials in light water reactors[1] These alloys have many advantages as the excellent neutron economy and the small capture cross sections, their resistance to oxidation is reduced when subjected to high temperatures during the reactor operation. This will result in an increase of hydrogen absorption that affects the microstructure of the material beside it loses ductility as the time proceeds[2]. The high oxidation resistance[11] and strength of SiC-based materials in high-temperature steam environments make these materials favorable in the study of ATF (accident tolerant Fuel) concepts

Methods

Results

Conclusion