It’s been more than a month since the Palisades Nuclear Plant near South Haven shut down after an unexpected release of slightly radioactive water into Lake Michigan.
Nuclear watchdog groups are upset there was yet another leak into the plant’s control room last week.
Entergy spokesman Terry Young says the leak was caused when sparks from welding work damaged a tarp separating the leaky tank that’s under repair from the control room below.
“Total leakage into the control room was less than four tablespoons of water,” Young said. “Now with that said, no water intrusion is acceptable to us. But I just want to emphasize that this posed absolutely no threat to safety of personnel or equipment.”
Federal regulators could not confirm the amount of the leakage, beyond “three drops per minute, for less than 24 hours.” Young says the water came from nozzles that are attached to the tank. The tank was drained, and the nozzles capped, but he says the water likely came from one of those nozzles.
“After last year’s leak into the control room the company put a tarp and catch trays in the catacombs,” Nuclear Regulatory Commission spokeswoman Viktoria Mitlyng said.
The tank sits on the roof, below the roof are catacombs and below those is the control room’s ceiling.
“They cannot start up without finding and fixing whatever caused the leak into the control room,” Mitlyng said. She says the NRC has six specialists on site, in addition to the two resident inspectors.
Kevin Kamps of Beyond Nuclear says he asked about the former leaks into the control room as recently as last month. “I was told by company and agency spokespeople that that issue was a thing of the past, that an installed moisture barrier had taken care of the problem,” Kamps said in a written statement.
“If Palisades can’t even prevent basic leakage through the ceiling of the control room, which has now been going on for over two years, what does that say about its reactor and radioactive waste safeguards?”
Young says a new “spill barrier” is on site. He couldn’t say immediately if the company considered it a permanent fix.
During repairs, the company realized the flooring beneath the tank was not built as drawings indicated. Specifically, a sand bed the tank was supposedly resting on did not exist. The company had assumed that low level leakage after the tank was repaired last summer was due in part to the sand bed being wet.
“It was impossible to say where those very low levels of leaks were coming from because there were no detectable flaws (in the tank) through any of the examinations,” Mitlyng said. She says the leak had not stopped after the repairs last year, but that the rate was low enough it wasn’t against regulations.
The tank is original construction, so Young points out the lack of a sand bed was done decades ago by a different company. Entergy bought Palisades in 2007 from Consumers Energy.
“At the time the decision was made not to put sand under there, they also did not update the drawings,” Young said. “So we assumed it was there. It turns out that is wasn’t. But what we put in place now is even vastly superior to what that sand would have done.”
The new sub-flooring will consist of a fiber board with reinforced concrete.
Repairs of the leaky tank continue. Young says workers are expected to finish the partial replacement of the tank bottom this week and begin a series of tests to confirm the tank is fixed. Young expects the plant will likely restart in early summer.