Studying the Correlation Between Swelling, Radiation Damage Rate, and Temperature in Nuclear Reactor Materials Using Ion Irradiations
Abstract
The radiation damage community has increasingly turned toward ion irradiations to fill a gap arising from the absence of high flux reactors in the testing of alloys for Generation IV reactors and current reactor fleet applications. While ion irradiation has numerous advantages in this testing realm, there are also a number of neutron-atypical variables that distinguish ion damage from neutron damage, including damage rate effects, microchemical phase changes, the injected interstitial effect, and the surface effect. Focusing on the radiation-induced swelling in particular, these atypical variables can significantly alter the observed results of ion experiments from that which would be seen in a reactor environment. This thesis addresses the credibility of ion simulation of swelling applied to neutron environments by presenting a series of ion irradiations on the simple chemical system of relatively pure iron across a range of irradiation conditions. The objective is to clarify the physics of void swelling under ion irradiation and demonstrate a microstructurally-based experimental method for determining, in self-ion-irradiated metals, the regions that are relatively free from injected interstitial and surface effects. A method for determining the optimum combination of dpa damage rate and temperature to avoid these phenomena and more accurately predict neutron-induced swelling trends is also presented. Finally, the results of the developed methodology resulting from the pure iron work is applied to simulate neutron induced swelling using “neutron-preconditioned” samples with experiments performed on AISI 304 SS samples previously irradiated in the EBR-II fast reactor. These specimens were irradiated to higher damage levels over a range of temperatures using 5MeV iron ions. The results show that preconditioning followed by the right range of ion irradiation parameters can yield incredibly valuable predictions of higher neutron-induced swelling levels without the difficulties arising from trying to achieve such high dose levels in a reactor environment.
Citation
French, Aaron James (2022). Studying the Correlation Between Swelling, Radiation Damage Rate, and Temperature in Nuclear Reactor Materials Using Ion Irradiations. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /198785.