If You're Excited By That $1.5B Michigan Nuke Plant Revival, Bear In Mind It's Definitely A Fixer-upper

Analysis A shuttered Michigan nuclear power plant is going to need a lot of work to get back online, according to atomic watchdogs. But its operators say the project is still on track despite extensive steam tube damage.

After reporting on a $1.5 billion loan from Uncle Sam to Holtec International to revive the Palisades nuclear power plant, The Register learned that an inspection of the steam generators at the facility found damage that "far exceeded estimates based on previous operating history," according to US Nuclear Regulatory Commission (NRC) documents. 

We knew Palisades historically had trouble with its steam generators, but this is another level.

This comes after the NRC reported trouble with the steam generator tubes at Palisades in mid-September [PDF], notifying the public that Holtec's preliminary analysis of the facility "identified a large number of SG [steam generator] tubes with indications that require further analysis." 

That analysis has since been completed. In a recent conference call between Holtec and NRC officials, the extent of the damage was revealed: A whopping 1,163 tubes displayed signs of outside diameter stress corrosion cracking (ODSCC). For reference, each of the two steam generators at Palisades contains 8,219 nickel-chromium-iron (alloy 600) steam pipes, through which flows pressurized, hot (and radioactive) water from the fission-powered reactor that is used to heat non-radioactive water to turn a turbine. 

Given the critical nature of such pipes in keeping radioactive water isolated, they need to be kept intact – so Palisades is going to need to make serious repairs to that system before even thinking about getting NRC certification to restart. The NRC noted that a total of 949 of the tubes are potentially candidates for plugging or repair.

We expected to find areas requiring additional maintenance during our proactive inspections and planned for this contingency

Nick Culp, senior manager of government affairs at Holtec Palisades, told The Register that, even though the initial estimates might have been lower, the firm has planned for just such surprises. 

"We expected to find areas requiring additional maintenance activities during our proactive inspections and planned for this contingency," Culp told us in an email. He noted that the issues in the generator pipes, in particular, "were not entirely unpredicted given the intention at shutdown was to dismantle and decommission the plant, which resulted in a standard system layup process not being followed." 

Per the NRC documents, the layups that weren't properly conducted in this case were "wet layups" – a process where pipes are filled with chemically treated water to prevent corrosion. This protective measure was delayed because the plant was initially slated for decommissioning. However, after Holtec acquired the plant and decided to restart it instead, the system remained untreated for some time, allowing corrosion to develop in the steam generator tubes​.

Palisades remains on track for a return to service by the fourth quarter 2025

Nonetheless, Culp said extra pipe damage won't slow the project down. "Palisades remains on track for a return to service by the fourth quarter 2025." 

The strategy for repairing the damaged tubes will be to unplug approximately 300 tubes per generator, followed by plugging tubes that can't be repaired. After that, the remaining repairable tubes will be fixed by "sleeving" them, which Culp said is a "common and proven repair strategy." 

"We expect these repairs will be completed within the original schedule of the overall outage and that the steam generators will not require replacement but will instead last for the full 30 years desired," Culp explained. 

Inspection of the Palisades reactor containment building dome and tendon system are currently underway, we're told, with preparations being made to inspect the main turbine soon. 

Palisades, a single 805 MWe pressurized water reactor built in 1971, was bought by Holtec from Entergy in June 2022 with the aim of resurrecting it. About a month earlier, it had been shut down by Entergy after it struggled to keep the station operational while competing against cheaper fossil fuels.

Activists go nuclear

Anti-nuclear activists at Beyond Nuclear, Don't Waste Michigan, and Michigan Safe Energy Future pushing to block the Palisades restart on Thursday argued the NRC's latest report is simply further evidence the Holtec initiative is "unneeded, insanely expensive for the public, and extremely high-risk for safety, health, and the environment." 

The campaigners went as far as warning, "If the reactor were allowed to restart, it would put one of the oldest US nuclear power plants at risk of a meltdown."

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Arnie Gundersen, a former nuclear executive and engineer with a 44-year career in the field who has since become a nuclear safety advocate retained by the Michigan groups trying to stop Palisades' restart, laid the blame for the pipe failure largely on Holtec, arguing the tubes deteriorated significantly on its watch due to a delay in performing that preventative layup.

"When Entergy sold Palisades for scrap, it did not place plant systems in 'wet layup,'" Gundersen said. "It is still unclear whether wet layup was delayed by weeks, months, or longer, very likely resulting in accelerated corrosion of SG tubes.

"Because the system was not placed in a proper wet layup, extensive corrosion was discovered on the outside diameter of steam generator tubes."

For what it's worth, NRC documentation [PDF] noted four tubes were found suffering axial ODSCC during a refueling outage that concluded in 2020. By the time of further inspections in 2024 for the restart, that number had ballooned to 1,163.

We've asked Holtec to confirm the timing of when the steam generator pipes entered the wet layup.

Problems go beyond pipes, say opponents

"I've watchdogged Palisades closely for 32 years," Beyond Nuclear radioactive waste specialist Kevin Kamps told The Register. "We clearly knew 18 and a half years ago that Palisades' steam generators needed to be completely replaced … because Palisades' original owner-operator, Consumers Energy, admitted it verbally and in writing." 

In the same 2006 presentation by Consumers on its planned auction of Palisades that mentions necessary steam generator repairs, the operator noted that several other "significant future capital expenditures" would be needed to keep the plant online. 

None of these concerns were addressed by Entergy, and none of these concerns are being addressed by Holtec – not in any adequate way, and in some cases, not at all

Along with replacing steam generator equipment, Consumers noted the reactor vessel head needed replacing, new fire protection equipment was needed, sump strainers had to be swapped out, and there were concerns about the embrittlement of the reactor pressure vessel.

"None of these concerns were addressed by Entergy, and none of these concerns are being addressed by Holtec – not in any adequate way, and in some cases, not at all," Kamps charged. "Holtec hopes to do as little repair and replacement as it can get away with, and then just fire up Palisades as is." 

Entergy bought the plant from Consumers Power (now Consumers Energy) in 2006, which later sold it (in a shutdown state) to Holtec. Plans to restart the plant were announced in September 2022.

In good nick

Holtec responded by telling us that the reactor vessel and head have been regularly inspected over the years, and stressed that Palisades operated in the NRC's highest safety category prior to shutdown – before Holtec owned it, we note.

"The plant completed consecutive record-breaking production runs before scheduled shutdown, a testament to the plant's material condition and continuous investments and preventative maintenance," Culp told us. "Palisades will continue to operate under the independent federal oversight of the US NRC, like all operating US nuclear plants."

Palisades has also been facing opposition from one of its own: Alan Blind, Palisades' engineering director from 2006 to 2013, has filed a petition with the NRC to stop the revival project. Blind expressed concern that the NRC was granting safety exemptions for the plant rather than taking the opportunity to establish a safe re-commissioning procedure, and asked the commission to pause granting Palisades a new license and instead create some actual rules.

The NRC is now seeking public comment [PDF] on the matter. ®