Nuclear reactor and advanced power system components are designed to perform for decades in extreme environments, including at high heat and pressure, without cracking or failing. To meet this challenge, the Department of Energy's (DOE's) Oak Ridge National Laboratory (ORNL) and KVA Stainless (KVA) have completed a major validation study on welded Grade 91 steel, an advanced alloy used in high-temperature energy systems.
Because it requires highly specialized equipment, lengthy testing and deep expertise in advanced materials science, research of this kind is often difficult for private companies to handle alone. ORNL's Materials Science and Technology Division (MSTD) has a long history of cutting-edge materials science research. In this case, ORNL researchers helped KVA to validate its technology using the MSTD's world-class, specialized facilities and lab expertise, both of which would otherwise be difficult and expensive to obtain. Backed by DOE's Technology Commercialization Fund (TCF), ORNL and KVA collaborated on the resulting report, Advanced Structural Material Welded Joints Characterization and Properties Testing.
Bridging the gap between research and industry
Intended to deliver energy solutions for the benefit of communities nationwide, the TCF Voucher Program - which debuted in 2023 - was designed to bridge the gap between development and commercialization of new technologies. By granting small businesses, local governments and other non-traditional partners access to the vetted resources and expertise they need, TCF helps advance energy technologies toward market readiness.
This research team's final report exemplifies ORNL's successful stewardship of the TCF program (and others like it) - programs that nurture productive, game-changing connections between laboratory research and industrial marketplaces. The results may also inform current (fission) and anticipated (advanced fission and fusion) approaches to nuclear energy, helping to determine whether critical welds can hold safely for decades. Both power-production techniques are certain to incorporate incredibly tolerant components, including those comprised of alloyed metals.
Putting advanced materials to the test
"The ORNL team spearheaded this effort with mechanical testing in support of our industrial collaborators to verify joining performance, which will further develop KVA's advanced manufacturing technology," said Xiao-Ying Yu, group leader in ORNL's Advanced Nuclear Materials Group and principal investigator on the KVA project. "The results are important for KVA and will help them revise and improve their technology. The data are useful as a technical basis to support code development for material testing and validation."
"The voucher program was invaluable for strengthening our ties with ORNL," said Danny Codd, principal engineer at KVA Stainless. "We had previously worked with ORNL nuclear materials experts through DOE-funded small business innovation research grants. There's no substitute for collaborating with the brightest minds while leveraging best-in-class nuclear materials testing capabilities. Xiao-Ying and her knowledgeable team members Wei Tang, Yan-Ru Lin and Mikhail Sokolov performed the critical path testing and characterization we needed to vet our technology."
The ORNL team tested how the welded steel performed under harsh conditions, including high heat and long-term stress. Advanced tools helped the researchers examine the material at the microscopic level to confirm that the welds met performance expectations.
Although the team found encouraging results, they also concluded that additional research is necessary to improve understanding of the relationship between the welding process, heat treatment and the steel's internal structure. Forging a better understanding of these mechanical properties will help researchers arrive at more thorough conclusions (and more accurate predictions) of how the steel will behave after years of stress under extreme heat.
While actively working with the American Society of Mechanical Engineers' Boiler and Pressure Vessel code committees, KVA is helping to develop regulatory approvals for their new post-bead induction heat treatment process, which heats welded zones using electromagnetic energy for reduced stress, improved toughness and structural integrity.
Highlighting these ORNL material testing and validation results, KVA's current plan for next steps involves building on the data ORNL provided. The lab's findings will help to make an already high-functioning technology perform even better, under even more demanding conditions, including those found inside advanced nuclear reactors.
"ORNL offers our industrial partners well-established capabilities in materials R&D, particularly in developing new devices and joining for nuclear power plants," said Yu. "Our staff's deep knowledge and MSTD's full suite of testing capabilities are essential to acquire critical testing results and to evaluate the new technology's readiness for market entry."
Alongside optimized designs, significant gains in efficiency, safety, flexibility, cost and longevity are expected. Amid a resurgence of interest in nuclear energy - one with its nucleus in Oak Ridge - the timing couldn't be better.
"This is all possible due to the deep knowledge of and broad experience with materials R&D within the lab's MSTD, specifically in support of nuclear materials intended for use with fission and fusion," said Yu.
By enabling scientific discoveries that accelerate energy deployment and create economic opportunity for the nation, this important research exemplifies ORNL's mission to advance domestic manufacturing.
Supported by DOE's 2023 Voucher Program and developed by its Office of Technology Commercialization, Office of Clean Energy Demonstrations, and Office of Critical Minerals and Energy Innovation, both partners applied for Voucher Opportunity 2: Performance Validation, Modeling, and Certification Support. Among the first awardees of the Technology Commercialization Fund voucher program, teams were aligned according to industrial technical needs and ORNL's capabilities.
UT-Battelle manages ORNL for DOE's Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit https://energy.gov/science . - Chris Driver
