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

Nuclear power plant operators want to run for eight decades, but a federal lab in Washington state found 'critical gaps' in knowledge about how reactors age, Nov. 1, 2021  By Hal Bernton , Seattle Times, Seattle Times staff reporter

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. [ED. Nobody counts the carbon emissions in the full nuclear fuel cycle]]

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, ....................

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................

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.......

By the time the revised document was released, the NRC already had begun the relicensing process. https://www.seattletimes.com/seattle-news/nuclear-power-plant-operators-want-to-run-for-eight-decades-but-a-federal-lab-in-washington-state-found-critical-gaps-in-knowledge/

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