ZIRLO® Irradiation Creep Stress Dependence in Compression and Tension

Abstract

Abstract Fuel operating margins in recent years have decreased due to increases in fuel duty. In response, Westinghouse has developed an improved version of Standard ZIRLO®, denoted as Optimized ZIRLO™. This paper is a continuation of a previous paper reported by Foster et al. in 2009, which presented methods used to develop Optimized ZIRLO from Standard ZIRLO. The previous paper only outlined the experimental methods used to determine irradiation creep. This paper presents the detailed methods used to determine in-reactor creep and growth. In addition, in-reactor creep stress dependence in tension and compression will be evaluated. The results show that the: (1) In-reactor creep compliance is the same in tension and compression and (2) if total in-reactor strain is split into irradiation growth and creep components: (a) Deviatoric hoop stress component and/or the stress difference of hoop minis radial is the driving force for irradiation creep and (b) irradiation creep in tension is the same as compression. These are the first experimental results that explicitly demonstrate the relationship between irradiation creep (or alternately plastic deformation under a neutron flux) with the deviatoric hoop stress component and/or the stress difference of hoop minis radial.