Large number of SG tube flaws at Palisades

Steam Generator Degradation Has Been Known at Palisades Nuclear Plant for Two Decades

Question Remains: Will NRC Require Safety-Significant System’s Replacement, or Not?

See a photo of SG tubes, above.

Beyond Nuclear’s radioactive waste specialist, Kevin Kamps, responded: “Consumers Energy notified the Michigan Public Service Commission in spring 2006 that Palisades’ steam generators needed replacement, for the second time in the plant’s history. However, Palisades’ next owner, Entergy, never did so, from 2007 to 2022, as NRC did not require it. We’ve been warning about this pathway to reactor core meltdown, one of many at Palisades, for two decades.”

One of Palisades’ two steam generators, Steam Generator A, already has 666 of 8,219 tubes effectively plugged, or 8.1%, this according to a 2020 inspection report (see Table 4-16, Number and Percent of Tubes Plugged, on Page 24, or Page 27 of 73 on the PDF counter). This does not account for further tube degradation in the 2021-2022 operational time frame, nor the 2022 to present shutdown status of accelerating corrosion due to lack of active safety maintenance, namely wet layup on the steam generators. One or a few tubes rupturing during full power operations might not progress to a catastrophic failure, although radioactively contaminated steam could be released to the environment. But a “cascading” failure of a large enough number of steam generator tubes can result in a Loss of Coolant Accident (LOCA), and consequent, catastrophic reactor core meltdown.

In a 1982 NRC-commissioned report — CRAC-II — carried out by Sandia National Lab, the following consequences were estimated for a Palisades reactor core meltdown: 1,000 peak early fatalities (acute radiation poisoning deaths); 7,000 peak early [radiation] injuries; 10,000 peak cancer deaths (latent cancer fatalities); and $52.6 billion in property damage. Adjusted for inflation alone, property damage would surmount $168 billion, expressed as Year 2023 dollar figures. And as Associated Press investigative journalist Jeff Donn reported in his four-part 2012 series “Aging Nukes,” populations have grown significantly since 1982 near atomic reactors like Palisades, so casualty figures would now be worse. (CRAC is short for Calculation of Reactor Accident Consequences; the report is also referred to as the 1982 Sandia Siting Study or as NUREG/CR-2239.)

In June 2013, two reactors at San Onofre, California were permanently shut down, due to extensive, worsening degradation of steam generator tubes. The owner/operator, Southern California Edison, proposed, and NRC was open to, operating the reactors at 70% power levels, in an attempt to mitigate the risks. But the response from area residents and environmental watch-dogs was overwhelming, forcing the company to pull the plug on any future operations. Arnie Gundersen, chief engineer at Fairewinds, served as an expert witness for Friends of the Earth at San Onofre. Gundersen now serves as an expert witness for an environmental coalition (Beyond Nuclear, Don’t Waste Michigan, and Michigan Safe Energy Future) intervening to block Palisades’ restart, including due to safety concerns about the severely degraded steam generators.

Gundersen has long warned about the lack of active safety maintenance at Palisades since Entergy shut the reactor for good on May 20, 2022. For example, the steam generators should have been placed into a chemically preservative “wet layup,” if they were ever meant to operate again, or else degradation would accelerate. This appears to be the case. At an August 1, 2024 public meeting about the Palisades restart scheme held at Lake Michigan College in Benton Harbor, MI, Beyond Nuclear’s Kamps asked NRC resident inspector April Nguyen if active safety maintenance has taken place at the reactor since Holtec took over on June 28, 2022. Nguyen responded that inspections would be conducted.

“That’s not what I asked,” said Kamps. “I’ll take that as a ‘no,’ active safety maintenance has not taken place at Palisades for the past two and a half years, so steam generator degradation has very likely accelerated on Holtec’s watch,” he added.

NRC’s Preliminary Notification of Occurrence begins:

“On August 24, 2024, with the plant defueled, Holtec, the owner of the Palisades Nuclear Plant, commenced steam generator (SG) tube inspections in their two SGs. The steam generators are large heat exchangers that transfer heat from the primary coolant system (reactor vessel) to the secondary plant systems (main steam system). The inspections were planned as part of Palisades’ restart activities. Experienced NRC inspectors were on-site and observed the SG inspections.

During Holtec’s analysis of the inspection data, preliminary results identified a large number of SG tubes with indications that require further analysis and/or repair. Further data analysis is in progress with additional tube inspections, testing, and repairs to be completed over the next few months.

There is no impact on public health. The unit remains defueled.”

Michigan Public/NPR quoted a spokeswoman for NRC’s Region 3 in the Midwest: “The plant’s not operating. The unit remains defueled,” said NRC spokesperson Prema Chandrathil. “And there’s no immediate safety concern or impact to public health.”

“Well, that’s our hope, in fact, to keep Palisades defueled, and prevent it from ever operating again, to threaten public health, safety, and the environment,” said Michael Keegan, co-chair of Don’t Waste Michigan in Monroe. “Restarting the reactor without entirely replacing the steam generators is playing with fire. But there are numerous other critical safety systems that could also be at the breaking point as well, some of which have not been inspected for a decade,” he added.

In addition to “Steam generator replacement,” Consumers Energy’s admissions to the Michigan Public Service Commission in spring 2006, regarding needed work on critical safety-significant systems, structures, and components at Palisades included: “Reactor vessel head replacement”; “Reactor vessel embrittlement concerns”; “Increasing NRC fees and fire protection requirements”; and “Containment coatings and sump strainers”. [See the full 2006 Consumers Energy slideshow presentation to MPSC, here.]

In a July 5, 2022 application for billions of dollars in taxpayer bailouts, secretly submitted to the U.S. Department of Energy, Holtec indicated it was considering entirely replacing the degraded steam generators, as part of its restart scheme. Holtec stated it could manufacture the new, replacement steam generators at its facility in Camden, New Jersey, at a cost of $510 million. This was the single largest line item expense listed in Holtec’s restart strategy document, obtained by Beyond Nuclear via a Freedom of Information Act request to the State of Michigan.

However, in a Nuclear Intelligence Weekly interview published April 5, 2024, Holtec/Palisades spokesman Nick Culp indicated that there was no longer any plan to replace the steam generators.

The article reported:

But skeptics are not convinced. “The list of construction problems that Holtec identifies is extraordinary and shows that the physical condition of the Palisades Plant deteriorated terribly while Entergy was the owner,” Arnie Gundersen, chief engineer for Fairewinds Associates and a former industry executive, said in a December petition to intervene and request for a hearing filed in the Palisades restart docket at the NRC. Gundersen references an itemized list of expenses to support the Palisades restart included in Holtec’s July 2022 application to the Civil Nuclear Credit program. In the application, Holtec also estimates a cost of $510 million for steam generator “design, fabrication, replacement (includes reactor coolant system redesign, cold-hot-fuel testing),” but Culp said this week that recent “expert testing and analysis has validated the integrity of our steam generators to support continued safe and reliable operation,” and the machines will not be replaced.

“It is not yet clear, given the inspection findings flagged in the September 18, 2024 NRC Preliminary Notification of Occurrence, whether or not Holtec will stick with its earlier, false assurance that the steam generators do not need to be entirely replaced prior to restart,” Kamps said.

“Holtec believes that a little putty and a little paint will make things look like what they ain’t!”, Gundersen added.

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