Speaker
Description
High-energy proton and neutron radiation change the microstructure and composition of structural materials during operation. These changes typically cause an increase in the strength and decrease in the ductility of the material with increasing dose. Administrative lifetime limits are applied to components in high-radiation environments at the Spallation Neutron Source (SNS) to limit the risk of failure associated with embrittlement. A post irradiation examination (PIE) program is maintained at the SNS to evaluate the change in mechanical properties of target vessels and proton beam windows (PBW). These results are evaluated to ensure the component lifetime limits are appropriate and the components are operating in a safe condition for the longest lifetime possible. However, peculiar deformation behaviors were recently observed in samples from 316L target vessels and Inconel 718 PBW samples at the SNS. Traveling wave deformation bands were observed in 316L target vessel specimens and an increase in elongations with increasing dose was observed during testing of Inconel 718 specimens. These behaviors complicate lifetime limit evaluations and present a new challenge to establishing appropriate component lifetime limits. This presentation will include a description of the dose limit philosophies used at the SNS, and recent findings from PIE of targets and PBWs will be presented and discussed.
| Themes for the contribution | 3 Post-irradiation examination: |
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