Holtec, the company that wants to re-open the Palisades nuclear reactor in Michigan, found corrosion cracking in steam generators that ‘far exceeded’ estimates, the USA’s Nuclear Regulatory Commission said in a report published on 2 October, reports news agency Reuters.
President Joe Biden’s administration this week finalised a $1.52 billion conditional loan guarantee to the Palisades plant. It is part of an effort to support nuclear energy, to curb climate change and to help satisfy rising electricity demand from artificial intelligence, electric vehicles and digital currency.
Palisades, which was closed down under a different owner in 2022, is seeking to be the first modern US nuclear power plant to reopen after being fully shut down. A summary of the early September call between the NRC and Holtec said that indications of stress corrosion cracking in tubes in both of Palisade’s steam generators ‘far exceeded estimates based on previous operating history.’ It found 1163 steam generator tubes had indications of the stress cracking. There are more than 16 000 tubes in the units.
Holtec wants to return the plant to operation late next year. Patrick O’Brien, a company spokesman, said the results of the inspections “were not entirely unpredicted” as the standard system procedure for maintaining the units was not followed when the plant went into shutdown. But he said the return of Palisades is still on schedule and that Holtec wants to repair, and not replace, the steam generators, which he said would then last for 30 years.
“We expect the repair strategy will be to ‘unplug’ approximately 300 tubes per steam generator that were plugged at original installation, and then address the tubes found during the inspections by plugging approximately 20% of the tubes that cannot be repaired easily and repairing the remaining 80% with sleeving, which is a common and proven repair strategy,” O’Brien said.
Holtec still needs permits from the NRC. It will require Holtec to ensure that the generators will meet NRC requirements if the agency authorises returning the plant to operational status.
The NRC said in September that preliminary results from inspections identified a large number of steam generator tubes, with indications that require further analysis and/or repair.
Steam generator issues are not new. Parts of the San Onofre Nuclear Generating Station in California were shut in 2012 after leakage from steam generators that had a design flaw. Problems with new generators led to the closure of the plant in 2013.
