震災危險性再評估 美東2核電廠超出安全停機值

Massachusetts Senators Edward Markey and Elizabeth Warren today called on the Nuclear Regulatory Commission to direct the licensees of Pilgrim Nuclear Power Station in Massachusetts and Seabrook Station in New Hampshire to immediately implement mitigation measures against seismic risks that were previously unknown.

Reports released Thursday by the NRC reveal that dozens of reactors that reassessed their vulnerability to earthquakes in the wake of the March 2011 meltdowns at Japan’s Fukushima Daiichi nuclear plant are at greater risk than they were originally licensed to withstand.

On March 31, 2014, licensees of all reactors in the continental and eastern U.S. submitted these seismic hazard re-evaluations to the NRC.

These submittals indicate that for both Pilgrim’s and Seabrook’s reactors and spent fuel pools, the new earthquake hazard is greater than the so-called “safe shutdown earthquake”, which is defined to be “the maximum earthquake potential for which certain structures, systems, and components, important to safety, are designed to sustain and remain functional.”

The two million watt Pilgrim nuclear power plant, operated by Entergy, is located 38 miles southeast of Boston, Massachusetts. The updated seismic data shows that Pilgrim could feel the effects of earthquakes as far away as 400 miles, double the previously estimated distance.

Seabrook is located 13 miles south of Portsmouth, New Hampshire, 56 miles north of Boston. It generates 1.2 million watts of electricity, enough to supply the annual needs of 1.2 million families. The licensee is NextEra Energy Seabrook, LLC.

“We urge you in the strongest possible terms to direct the licensees of the Pilgrim Nuclear Power Station and the Seabrook Station to immediately take all necessary measures to assure the safety of the reactors and those that live and work near them,” write Senators Markey and Warren to the NRC chair.

One of the recommendations of the NRC’s Near Term Task Force report following Fukushima was that licensees re-evaluate seismic hazards at each reactor using current research and models in order to develop a better understanding of possible earthquake hazards at the site and determine whether additional safety measures are needed.

Licensees of all reactors in the continental and eastern U.S. submitted these seismic hazard re-evaluations to the NRC in March. Now the licensees of several dozen reactors must analyze their structures and components for earthquake risk at an estimated cost of roughly $5 million for each analysis.

Two industry experts told the “New York Times” earlier this month that across the central and eastern United States, plants at 24 sites reported that the new earthquake threat was larger than what they were designed to face. The commission has not released a total yet.

Licensees are given until 2017 to complete their analyses, but the Massachusetts senators are asking the Nuclear Regulatory Commission to direct Entergy not to wait that long but to require the company to “more quickly implement mitigating measures for the reactor equipment that would be needed to safely shut down the reactors in the event of an earthquake.”