The Nuclear Regulatory Commission says they found no problems with the response to cracks in concrete at Seabrook Nuclear Power Plant during a recent inspection.
Their new report is another step forward in the power plant's bid to get its license renewed.
Seabrook is the only commercial nuclear plant in the country known to be experiencing a chemical reaction that causes its concrete to expand and crack.
The reaction, known as ASR, was discovered in 2010 – just as the plant’s owner, Florida-based NextEra, applied to extend its operating license through 2050.
The concrete issue has been spreading since then, but regulators have said repeatedly that it isn’t a public safety threat.
As part of the license renewal process, they’ve asked NextEra to show a solid long-term plan for addressing the problem. In May, inspectors went to the plant to see how that was going.
NRC spokesman Neil Sheehan says this inspection found “reasonable assurance” that the plant is monitoring and addressing the issue in a way that protects public safety.
"You can't ever say anything with one hundred percent certainty,” he says. “But certainly there's adequate safety margin there that the components of the plant would still be able to perform their function, and the plant would remain in a safe condition” if the cracks worsened.
Seabrook's next hearings on the cracks and its license application take place this fall.
The local nuclear watchdog group C-10 will also get to raise concerns about the concrete cracks and other issues at its own public hearing with the NRC next spring.
Seabrook will be the one of two nuclear plants still operating in New England once Pilgrim Station, south of Boston, shuts down next year. The other is Millstone in Connecticut. Right now, the plants often supply around a third of the electricity used by the New England grid.
CORRECTION: An earlier version of this article incorrectly stated that Seabrook would be the only nuclear plant left operating in New England after Pilgrim Station in Massachusetts closes next year. In fact, it will be the only plant still operating in Northern New England; Connecticut's Millstone plant is also still open.