Entergy faces another special investigation over malfunction at Palisades

The Nuclear Regulatory Commission has sent a special investigation team to Entergy’s Palisades nuclear power plant to examine the circumstances around the plant’s latest unplanned shutdown.

Palisades 798 MW pressurized water reactor, located about 70 miles southwest of Grand Rapids on Lake Michigan, abruptly powered down on Sunday night when an electrical malfunction took out the power supply to several safety-related valves and switches.

“The issue involved plant workers who were performing maintenance activities on an electrical panel when a small metal piece located inside the breaker panel came into contact with another metal piece and caused an arc,” the NRC said Wednesday. “This resulted in a series of electrical issues that caused the plant to shut down and sent signals to multiple plant systems causing certain safety pumps to start and some safety valves to reposition.”

Officials say the plant has been controlling temperature by venting steam, that contains low levels of tritium, into in the environment.

Tritium is a radioactive isotope of hydrogen that has a 12-year half life.

“The plant is in a safe shutdown condition but we have a number of questions about the complexity of the series of events that led to the reactor trip and want to better understand the actions taken by the plant staff before the reactor shutdown and in response to the event,” said NRC Region III Administrator Mark Satorius.

The agency said it will release a report from the special investigation within 45 days.

The shutdown at Palisades is the second this month and occurred just five days after the plant restarted from a shutdown triggered by a leak in the plant’s cooling system. The NRC has not yet released the report from the special investigation into that event. The agency also inspected the plant in August after a water pump failed.

With three problematic incidents this quarter, Palisades may be flagged for ongoing additional oversight by the NRC.

“This would be appropriate,” said David Lochbaum, a nuclear power expert with the Union of Concerned Scientists, “but NRC should go a step further and look to see if there is a corporate hand in the problems.

“Anytime there is a series of problems, it’s worth checking,” he said, “Are the plants being given enough money for operations? Are appropriate standards in place?”

In Vermont, where Entergy is fighting to continue operating its highly-controversial Vermont Yankee power plant, citizens groups and public officials have criticized the company for inadequate maintenance and lying about safety matters.

In 2007, corroded bolts and rotten wood caused one of Vermont Yankee’s cooling towers to collapse.

In 2009, plant officials testified that Vermont Yankee had no underground pipes that carry radioactive materials, but in 2010, it was discovered such pipes did exist and had been leaking tritium contaminated water into the ground for years.

This revelation prompted an investigation by Vermont’s Public Oversight Panel, which determined the company’s misstatements about the underground pipes where part of corporate culture that neglects preventative maintenance and, “a systemic history within the organization of not telling the truth when the truth must be told.”

Entergy’s lies about the pipes led Vermont Attorney General Bill Sorrel to launch a criminal investigation.

“Entergy and certain of its personnel have acted in at best an untrustworthy manner,“ Sorrell said in July after a months long probe, “however we lack the smoking gun evidence to prove to our satisfaction that this untrustworthy behavior is criminal.”