Researchers have conducted years of experiments to learn more about how different parts of the power plants age when exposed to a harsh mix of pressures, water chemistry and radiation.
Despite all this testing, questions remain about the long-term wear, beyond the 60 years for which plants are licensed. So the Nuclear Regulatory Commission that conducts relicensing contracted with the Pacific Northwest National Laboratory in Richland to develop a kind of road map for future study.
That report was published online in 2017 by the federal laboratory. It detailed a series of "critical gaps" in knowledge, and proposed an ambitious research plan to help fill them in by studying parts pulled from shuttered nuclear power plants.
This report got a chill reception at the NRC.
Some commission staff thought some of the report's wording was inaccurate or misleading and could lead readers to believe "we should not be issuing renewed licenses" to run for up to eight decades, according to emails and other documents obtained under the federal Freedom of Information Act.
"I think the entire report needs to be scrubbed for text that points to gaps and, if issued, we need a stronger basis for why we will grant renewed licensing ... before harvesting [of parts from shutdown reactors] and testing is completed," wrote one NRC staffer.
The report was substantially revised by the NRC, which in 2019 released a toned-down version of the report that deleted all seven references to critical gaps in knowledge.
The rocky path of this study through the federal regulatory commission offers an unusual window into the launch of a licensing renewal that is expected to determine the fate of most of the current generation of U.S. nuclear power plants.
This fleet of more than 90 reactors produces about one-fifth of the nation's electricity — and does so without the direct release of carbon emissions while operating.
Most of these reactors, including the Columbia Generating Station, are licensed to operate for up to 60 years past their initial startup date.
Without license extension to operate for an additional 20 years, almost all of them would have to shut down during the first half of the 21st century, a pivotal period in the struggle to reduce carbon dioxide and other greenhouse gases driving climate change.
Robert Schuetz, CEO of Energy Northwest, which operates the Columbia Generating Station, said that the Washington reactor, which started generating power in 1984, has an extensive maintenance program. And he is convinced the plant could run until 2063 rather than shut down in 2043 when the current license expires.
"We think the technology supports an extended operation," Schuetz said.
Scott Burnell, a spokesperson for the NRC, said that relicensing involves a thorough safety review, and that NRC officials are convinced there already "is sufficient information to appropriately manage the aging of the plants."
Burnell said the 2017 PNNL report was a draft document, although there were no markings to indicate that, and that the report underwent the "normal editing process."
Mark Nutt, nuclear energy sector manager at PNNL, said the initial version of the report was "inadvertently posted" and that all changes made in the final document "were intended to improve the accuracy of the report."
2017 report posted online, then removed
Paul Gunter obtained the NRC documents detailing the internal criticisms of the PNNL report. He is an activist with Beyond Nuclear, a group working for a world "free of nuclear power and nuclear weapons."
Gunter for years has watchdogged the relicensing of nuclear power plants, and more recently has been a vocal critic of the NRC's proposal to consider up to 80 years of operation for U.S. nuclear power plants.
"This is pushing to the extreme," said Gunter.
Gunter during an online search went to the PNNL website, and found a copy of the 2017 report.
He was encouraged by the authors' recommendations, and cited the study at a Sept. 26, 2018, meeting about relicensing convened by the NRC.
"I started asking questions and their jaws dropped, and they said, 'We can't be talking about this,' " Gunter recalls.
Soon after Gunter cited the report at the meeting, he said the report was pulled down from the PNNL as well as Department of Energy and International Atomic Energy Agency websites that had also posted the document.
Troubled by the effort to keep the 2017 report from public view, Gunter's organization then filed a federal Freedom of Information Act request to gain access to NRC documents related to the study.
These documents show how NRC's own research staff had questions about how important structures would hold up over 80 years of operations. A 2013 project description stated that "understanding and managing" how things degrade is "unquestionably a key need for continued safe and reliable" reactor operations, and "also an area with very significant uncertainties."
One of the most challenging areas involves embrittlement of metal in reactor pressure vessels that are bombarded by neutrons during the fission process. Extreme embrittlement could result in reactors having to reduce power production or shut down all together.
The aging of reactor internals and concrete, and deterioration of cables, also are concerns, according to NRC documents Gunter obtained.
Experiments underway
The PNNL is located north of Richland and is operated by the U.S. Department of Energy. It employs more than 5,300 staff involved in a wide range of science studies.
This work includes extensive experiments to learn more about how different parts of the power plant — including welds — age. In one laboratory, for example, metals are bathed in corrosive liquids for months and examined for fatigue cracks and other signs of wear.
"We are doing tests that simulate ... worse than the worst-case scenarios," said Ziqing Zhai, a scientist who conducts some of these experiments.
Even with such laboratory studies, the NRC research staff still had questions about the real-word aging of nuclear power plants that might differ from experiments.
So the NRC asked the PNNL researchers to come with a long-term plan to guide harvesting of high-priority parts from shutdown reactors that could then be analyzed and compared with the results from laboratory tests.
The study by PNNL's Pradeep Ramuhalli and four other scientists concluded such harvesting would be "essential to provide reasonable assurance that the materials/components will continue to perform their safety function throughout the plant licensing period."
That line was removed from the final report, which portrayed this research more as a useful option — rather than a necessity — and cautioned that it may not always be practical to salvage these parts.
Ramuhalli approved of changes made to the report, according to an email he sent to the NRC. Ramuhalli declined a request to be interviewed for this story, according to a spokesperson for PNNL.
Burnell, the NRC's spokesperson, noted that operators can use alternative ways to check for aging. Metal pieces known as "coupons" for example, are put in reactors and can be pulled out years later for study.
By the time the revised document was released, the NRC already had begun the relicensing process.
As of October, the NRC has approved operations of up to 80 years for six reactors. Applications for nine others are under review.
The NRC earlier this year also considered, then put on hold, a public discussion about possibly licensing reactors for as long as 100 years.
NRC will continue to study aging issues, and respond to new information that becomes available, according to Burnell.
Columbia Generating Station won't be eligible to apply for an extended license until 2023, but Energy Northwest is likely to request NRC approval for up to 80 years of operations.
"It's really a question of ... does the region want and need our power," said Schuetz of Energy Northwest. "It's carbon-free power. We think we are a good mix ... but we need to convince our stakeholders that it's the right thing."
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