A Rate Theory Model of Radiation-Induced Swelling in an Austenitic Stainless Steel

Malcolm Griffiths,Juan Ramos-Nervi,Larry Greenwood

doi:10.3390/jne2040034

Abstract

Many rate theory models of cavity (void) swelling have been published over the past 50 years, all having the same, or similar, structures. A rigorous validation of the models has not been possible because of the dearth of information concerning the microstructures that correspond with the swelling data. Whereas the lack of microstructure information is still an issue for historical swelling data, in the past 10–20 years data have been published on the evolution of the microstructure (point defect yields from collision cascades, cavity number densities, and dislocation densities/yield strengths) allowing certain gaps in information to be filled when considering historic swelling data. With reasonable estimates of key microstructure parameters, a standard rate theory model can be applied, and the model parameter space explored, in connection with historical swelling data. By using published data on: (i) yield strength as a function of dose and temperature (to establish an empirical expression for dislocation density evolution); (ii) cavity number densities as a function of temperature; and (iii) freely migrating defect (FMD) production as a function of primary knock-on atom (PKA) spectrum, the necessary parameter and microstructure inputs that were previously unknown can be used in model development. This paper describes a rate-theory model for void swelling of 316 stainless steel irradiated in the EBR-2 reactor as a function of irradiation temperature and neutron dose.

Highlights

Departamento de Materiales, Nucleoelectrica Argentina S.A., Francisco N
The effect of increasingatthe ratio of He atoms to vacancies within cavitiesset as of a a function of temperature high doses can be demonstrated using athe nominal function of temperature at high be demonstrated usingnm, a nominal set of density micromicrostructure parameters, i.e.,doses fixedcan grain diameter of 10,000 dislocation structure i.e.,infixed grain diameter
The dimensional stability of austenitic stainless steels is largely dependent on cavity swelling, which is dependent to some extent on having He present to stabilise cavities against collapse to vacancy dislocation loops

Summary

Introduction

Departamento de Materiales, Nucleoelectrica Argentina S.A., Francisco N. A material issue for stainless steel (SS) components in nuclear reactors operating at temperatures ≥400 ◦ C is radiation-induced swelling [1,2]. Swelling is an issue for existing fast reactors operating at high temperatures and neutron dose rates and is a concern for many new reactor designs [4]. Large volumes of material for accuracy), data obtained at high doses and temperatures offer the best source of accurate swelling data from which to derive a swelling model. Such data are largely derived from fast reactor irradiations

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