Publications

Sep, 2025

ORNL Report

Analysis of Helium-Induced Cracking in Laser Beam Weldments Performed on Irradiated 304L Austenitic Stainless Steel

This document presents the results obtained under an extension (Tasks 6–10) of the research contract with the Electric Power Research Institute (EPRI), under US Department of Energy proposal no. NFE-18-07249. The document finalizes the research activity performed earlier under two Rapid Turnaround Experiment proposals and the original research contract with EPRI (research…

Sep, 2025

ORNL Report

Analysis of Deformation and Fracture Mechanisms in the Harvested Low-Dose Baffle Former Bolt via Advanced Mechanical Tests

This report details the production of tensile specimens from in-service irradiated baffle former bolts (BFBs) and presents the results of a pilot in-situ SEM/EBSD test conducted at Oak Ridge National Laboratory’s Low Activation Materials Development and Analysis (LAMDA) facility. The SEM/EDS results confirmed that the material is AISI 316L steel, not AISI 347, and that no…

Sep, 2025

ORNL Report

Analysis of deformation mechanisms, strain localization, and fracture in highly irradiated austenitic steels – light water reactor core materials – via advanced in-SEM techniques

The present report describes the establishing of an advanced experimental approach – high-resolution digital image correlation or µDIC – for testing miniature irradiated specimens in the ORNL’s Low Activation Materials Development and Analysis (LAMDA) facility. As expected, the µDIC approach will allow for studying strain localization inside grains, for instance, during di…

Sep, 2025

ORNL Report

In-depth assessment of in situ SEM/EBSD experiments and fractography data

The present report provides a detailed, in-depth analysis of the in-situ SEM/EBSD tensile tests performed with non-irradiated and irradiated Zr-alloy specimens. Deformation mechanisms studied via in-situ mechanical tests (slip line/defect-free channel formation, twinning, etc.) are assessed with respect to their contribution to deformation band formation and material failu…

Sep, 2025

ORNL Report

Survey of baffle plate samples, specimen machining, and hydrogen measurements

This report outlines preliminary results on the survey and characterization of irradiated baffle plate, baffle former, and flux thimble tube specimens as part of the ongoing investigation into irradiation-induced embrittlement in austenitic stainless steels at ambient (room temperature) conditions. The specimens originated from commercial pressurized water reactor (PWR) co…

Sep, 2025

ORNL Report

Analysis of deformation and fracture mechanisms in the harvested high-dose baffle-former bolt with stress-corrosion cracks formed while in service

Jun, 2025

Journal

In-service corrosion and grain boundary oxidation in neutron-irradiated 316 stainless steel baffle-former bolts

Reactor core internal components such as baffle-former bolts (BFBs) are subjected to significant mechanical stress, corrosive environment, and neutron irradiation from the reactor core during the plant operation. Over the long operation period, these conditions lead to potential degradation and of the bolts. In this work, characterization was performed on the oxidized surf…

May, 2025

Journal

Impact of post-irradiation annealing on mechanical performance of irradiated 718 alloy

The effect of post-irradiation annealing on solution-annealed 718 alloy was investigated using advanced mechanical testing, fractography, scanning electron microscopy, and transmission electron microscopy. Specimens were extracted from a proton beam window operated at the Spallation Neutron Source, irradiated with 940 MeV protons to a maximum dose of approximately 9.7 disp…

Apr, 2025

Journal

Assessing the viability of a new subsize tensile specimen geometry for evaluation of structural nuclear and additively manufactured materials

The use of subsize specimens in nuclear materials testing has been a subject of ongoing interest due to radiation safety concerns and resource conservation needs. It is also of interest in additive manufacturing (AM), also known as 3D-printing, as subsize specimens can more accurately represent the behavior of the small, intricate geometries often produced using AM. A nove…

Apr, 2025

Journal

Beam current effect as a potential challenge in SEM-EBSD in situ tensile testing

In situ mechanical tensile tests coupled with electron backscatter diffraction (EBSD) analysis were conducted using specimens of two 304L steels with ~8 and 10.4% Ni content, respectively. Twinning was observed in steel with 10.4% Ni content, whereas steel with 8% Ni content demonstrated martensitic transformation. Testing showed that the kinetics of martensitic transforma…

Apr, 2025

Journal

How irradiation promotes intergranular stress corrosion crack initiation

Irradiation assisted stress corrosion cracking (IASCC) is a form of intergranular stress corrosion cracking that occurs in irradiated austenitic alloys. It requires an irradiated microstructure along with high temperature water and stress. The process is ubiquitous in that it occurs in a wide range of austenitic alloys and water chemistries, but only when the alloy is irra…

Apr, 2025

Journal

A potential emerging issue concerning repair welding of out-of-core PWR components involving tritium exposure and 3He retention

The present communication identifies a previously unrecognized risk of helium-induced embrittlement in out-of-core PWR components exposed to tritium-contaminated coolant. While previous weldability concerns centered on 4He accumulation in neutron-irradiated alloys located at in-core or near-core regions, new measurements show that 3He generated by tritium decay can accumul…