Fatigue life predictions for irradiated stainless steels considering void swellings effects Robert W. Fuller a , Nima Shamsaei b,c, ⁎, Jutima Simsiriwong c a Entergy Operations, Grand Gulf Nuclear Station, 7003 Bald Hill Rd., Port Gibson, MS 39150, USA b Department of Mechanical Engineering, Mississippi State University, Box 9552, Mississippi State, MS 39762, USA c Center for Advanced Vehicular Systems (CAVS), Mississippi State University, Box 5405, Mississippi State, MS 39762, USA article info abstract Article history: Received 25 July 2015 Received in revised form 25 September 2015 Accepted 6 November 2015 Available online 7 November 2015 The objective of this study is to estimate fatigue life of irradiated austenitic stainless steels types 304, 304L, and 316, which are extensively used as structural alloys in the internal ele- ments of nuclear reactors. These reactor components are typically subjected to a long-term ex- posure to irradiation at elevated temperature along with repeated loadings during operation. Additionally, it is known that neutron irradiation can cause the formation and growth of micro- scopic defects or swellings in the materials, which may have a potential to deteriorate the mechanical properties of the materials. In this study, uniaxial fatigue models were used to pre- dict fatigue properties based only on simple monotonic properties including ultimate tensile strength and Brinell hardness. Two existing models, the Bäumel–Seeger uniform material law and the Roessle–Fatemi hardness method, were employed and extended to include the effects of test temperature, neutron irradiation fluence, irradiation-induced helium and irradiation- induced swellings on fatigue life of austenitic stainless steels. The proposed models provided reasonable fatigue life predictions compared with the experimental data for all selected materials. © 2015 Elsevier Ltd. All rights reserved. Keywords: Fatigue Life prediction Stainless steel Neutron irradiation Elevated temperature Void swelling Irradiation-induced helium 1. Introduction With a growing demand to reduce greenhouse gas emissions, the focus of energy generation sources has shifted from fossil fuel- based electrical production to those that provide low emission, inexpensive, and reliable electricity such as nuclear power reactors. It was reported that approximately 19% of the total electrical supply in the United States in 2014 was generated from 104 commercial nuclear reactors at 62 nuclear power plant sites in operation nationwide [1]. While nuclear reactors are typically designed with an operational life of 40 years, their lives can be extended to 20 additional years or more with provisions for Licensing Renewal [2]. To ensure the safe operation of existing reactors beyond their initial design lives, understanding the long-term structural integrity of reactors is a major concern. One of the prominent issues related to failures in nu- clear power components is attributed to material degradation due to aggressive environment conditions, and mechanical stresses. For instance, reactor core support components, such as fuel claddings, are under prolonged exposure to an intense neutron field from the fission of fuel and operate at elevated temperature under cyclic (i.e., fatigue) loadings caused by start-up, shut-down, and unsched- uled SCRAM (emergency shut-down) [3]. The fluctuations in loadings typically occur a few hundred to a thousand times during the life of the vessels [4]. Pressurizer, steam separators, pumps, steam generator shells, piping, etc., are among the nuclear reactor components subjected to fatigue damage during operation [3]. Engineering Failure Analysis 59 (2016) 79–98 ⁎ Corresponding author at: Department of Mechanical Engineering, Mississippi State University, Box 9552, Mississippi State, MS 39762, USA. E-mail address: shamsaei@me.msstate.edu (N. Shamsaei). http://dx.doi.org/10.1016/j.engfailanal.2015.11.022 1350-6307/© 2015 Elsevier Ltd. All rights reserved. Contents lists available at ScienceDirect Engineering Failure Analysis journal homepage: www.elsevier.com/locate/engfailanal