NSUF 18-1387: Advanced microstructural and nano-hardness characterization of low penetration pulsed-laser weldments performed on highly activated neutron irradiated stainless steel
As the existing light water reactor (LWR) fleet ages, the weldability of structural austenitic materials used to construct reactor internals is diminished. This decrease in weldability is primarily attributed to the formation of helium from neutron transmutation reactions of boron and nickel. A collaborative research program supported by the EPRI Long Term Operations (LTO) and DOE Light Water Reactor Sustainability Programs (LWRSP) is currently underway to perform extensive weldability investigations on highly irradiated materials. The materials being used for this research are 304L and 316L austenitic stainless steels irradiated at the ORNL High Flux Isotope Reactor (HFIR) facility. Boron levels of these stainless steel materials were precisely controlled to produce a range of post-irradiation helium levels representative of LWR internals. However, the nature in which the irradiations were conducted on these materials are not expected to produce void swelling typically found in highly irradiated PWR reactor components. The post-weld characterization proposed herein will address this research gap by investigating the effects of welding on the mechanical and microstructural properties of highly activated 304L stainless steel irradiated in the INL Experimental Breeder Reactor-II (EBR-II). A series of welds were recently performed on this material at Westinghouse, which contains both considerable void swelling and helium levels in the microstructure. SEM-EBSD analysis will be performed at ORNL on these welds to characterize grain structure, texture, and the helium-void interaction on cracking, if any, in the HAZ. EBSD and back-scatter electron imaging will also allow for identifying areas of interest for further FIB lift-outs (high- or low-angle or special grain boundaries, cracks, if they appear, and presence of second phases such as delta-ferrite or martensite). TEM foils will be extracted from several locations of interest in the weldment, HAZ, and base material to investigate helium distribution within the microstructure. Furthermore, nano-hardness measurements will be taken in these same areas of interest to measure the effects of irradiation on hardness. The period of performance for this study is expected to be four to six months.
Información Adicional
| Campo | Valor |
|---|---|
| Awarded Institution | Electric Power Research Institute |
| Embargo End Date | 2024-05-09 |
| Facility Tech Lead | Alina Montrose, Kory Linton, Mukesh Bachhav |
| NSUF Call | FY 2018 RTE 2nd Call |
| PI | Jonathan Tatman |
| Project Member | Brian Gorman - Colorado School of Mines |
| Project Member | Dr. Frank Garner, President - Radiation Effects Consulting (https://orcid.org/0000-0003-4690-2205) |
| Project Member | Jonathan Tatman, Technical Leader - Electric Power Research Institute |
| Project Notes | Awarded on 05/17/2018 |
| Project Type | RTE |
| Publication | Radiation resistant fiber Bragg grating in random air-line fibers for sensing applications in nuclear reactor cores David Carpenter, Lin-wen Hu, Joshua Daw, Kevin Chen OSA Publishing, Optics Express 26 2018-10-01 https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-26-9-11775&id=385858 |
| Publication | Microstructure analysis of laser beam weldments performed on neutron-irradiated 304L steel containing 3 and 8 appm helium Maxim Gussev, Weicheng Zhong, Frank Garner, Paula Freyer, Jonathan Tatman, Jesse Werden Journal of Nuclear Materials 563 2022-05-18 https://www.sciencedirect.com/science/article/abs/pii/S0022311522001349 |
| RTE Number | 1387 |