The Palisades Nuclear Power Plant near South Haven has shut down again.
This is the second time this summer Entergy Corporation has had to shut down the plant for repairs.
The plant shut down to refuel in April; that was normal. It restarted in early May.
But then a water leak in a tank above the control room caused the plant to shut back down just a few weeks later. Those repairs took a month and on July 11th the plant started up again. Though that leak appears to be fixed, it is still under investigation by special federal agents with the Nuclear Regulatory Commission.
But as it returned to service in July, Palisades spokesman Mark Savage says operators discovered a different water leak – this time in the building that holds the nuclear reactor. In a written statement, Savage called the leak “minor.”
The company noticed this leak when they restarted the plant after fixing that first leak in a tank above the control room. This leak is in a different area of the plant – the containment building. This building holds the nuclear reactor itself.
Prema Chandrathil is a spokeswoman for the Nuclear Regulatory Commission. She says the leak is not a threat to public health.
“It’s contained and it goes into the plant’s waste storage tank," Chandrathil said.
Chandrathil says the situation at Palisades is “serious” though. The NRC now has a specialized inspector to assist regular inspectors at the plant while the company makes repairs.
Savage says they’ve determined that a “control rod drive package” is the source of the leak. There are 45 of these control rods. Plant operators can raise or lower control rods to control the rate of the nuclear reaction.
“And occasionally these control rod drives will have a problem. In this case we couldn’t identify it until we actually shut the plant down. So we take aggressive action to shut the plant down, do the right thing, make the repairs and return the plant to service," Savage said. (He's characterized this move as aggressive because Entergy Corporation could've waited until the leak got worse before the NRC would've required a shut down.)
But there are a lot of people, nuclear watchdogs in particular, who are quick to point out that Palisades has had a number of problems with these control rod drives.
This is the second time this year Palisades shut down to fix a leak related to these control rod drives. Back in January, they replaced some seals on the rods that were worn out.
But the Union of Concerned Scientists notes control rod problems at Palisades that go back decades.
“Other plants have similar designs and have at times in their past experienced problems but they were able to find the problem and fixed it the first or at worse, second time. Whereas Palisades is at more than a dozen times. Something’s wrong there and the company has yet to figure out what it is and fix it," Lochbaum said.
Indeed, Palisades’ spokesman Mark Savage says they have yet to determine the cause of the leak. Savage says they’ll completely replace at least one of those 45 control rod drive packages.
David Lochbaum with the Nuclear Safety Project says that’ll only work if it resolves the underlying problems. He says the NRC needs to do more to make sure the root cause is identified and fixed this time.
"At plants that we monitor that are doing a good job on nuclear safety; they don’t tolerate problems. They don’t allow problems to reoccur. They do their best efforts to go in and find out what’s causing a problem and fix it right the first time," Lochbaum said. "At some point the regulator, the Nuclear Regulatory Commission, needs to step in and compel (Palisades) to get to that successful destination."
Chandrathil says the NRC is doing everything it can. "We have a questioning attitude. We look at very specific areas and we have gone ahead and identified deficiencies at the plant. It’s up to the plant to improve their performance," she said.