Potential meltdowns at Japanese nuclear plant stir concerns here

Three nuclear power plants near the Philadelphia region have containment designs similar to the Fukushima Dai-ichi reactors in Japan that are facing potential meltdown.

Independent experts have said the design is vulnerable to explosions and should be reevaluated in light of the earthquake and tsunami that have disabled the Japanese reactors.

However, U.S. regulators and industry officials said that each plant has significant differences.

They said the nation's nuclear plants not only have robust safety measures that would enable them to withstand natural disasters, but also have undergone safety and security upgrades since the 9/11 incidents.

Three plants in this region - Hope Creek in Salem County, Oyster Creek in Ocean County and Peach Bottom in Lancaster County - use the same basic containment design as at the Dai-ichi reactors, a General Electric Mark 1.

But for all, physical structures, safety systems, and processes vary, said spokesman Scott Peterson of the Nuclear Energy Institute, an industry group.

The disaster in Japan, which appeared to worsen Monday with explosions and other setbacks, has focused new attention on U.S. plants, their safety, and whether President Obama's plan to build new ones to wean the country from foreign oil and forestall climate change will progress as he would like.The issues reverberate in Pennsylvania and New Jersey, home to one of the nation's largest concentrations of nuclear power, with eight plants. They incorporate 13 of the nation's 104 reactors. Oyster Creek is the nation's oldest operating plant.

Five of the region's plants are totally or partly owned by Exelon, which operates the nation's largest nuclear fleet.

The Hope Creek/Salem generating facilities in Salem County constitute the second-largest commercial nuclear power site in the United States.

Two companies have announced interest in building additional reactors. PSEG would build one at the Hope Creek/Salem site while PPL would place one near its Susquehanna plant in Berwick.

Edwin Lyman, a physicist with the Union of Concerned Scientists, a nonprofit that has been a nuclear industry watchdog for 40 years but has no formal position on the industry, said that if the core and reactor vessel melt through, the Mark 1 steel and cement containment building has a vulnerability that may allow it, too, to be breached, although he said specifics were "hard to predict."

"Some containments are better than others," he said. "The Mark 1 and certain other types are the worst ones, and I think a fresh look is going to have to be taken at whether they are satisfactory."

Michael Mariotte, executive director of the Nuclear Information and Resource Service, a nonprofit networking center for environmentalists, said that he has been raising alarms about the Mark 1 design for years.

So, he said, have engineers within the Nuclear Regulatory Commission. Now, "everything is going exactly as the early skeptics had unfortunately predicted," he said.

April Schilpp, an Exelon spokeswoman, said that "all of our nuclear facilities are designed to American seismic and flood standards, based on their local geographies. It's not a one-size fits all solution."

She said Three Mile Island, Oyster Creek, and Peach Bottom were recently re-licensed after "robust reviews."

But during Oyster Creek's review, enviromentalists contended that rust had corroded the plant's steel liner.

In 2009, the NRC voted to allow the plant to continue to operate another 20 years. But officials announced in December that they would close the plant by the end of 2019, rather than build cooling towers as required by the state.

Jeff Tittel, director of the New Jersey Sierra Club, said he remained concerned. "It's an old plant. The drywall liner has a very thin piece of steel. Can it corrode? Can even a small earthquake do something that triggers a real problem there? We don't know. We need to have that answered."

PSEG spokesman Joe Delmar confirmed that Hope Creek is a boiling water reactor with a Mark 1 containment and said that experts were still trying to get better information on the Japanese design. "There are differences."

But he said that both Hope Creek and Salem were designed to withstand the effects of natural disaster, including earthquakes, flooding, and tsunamis. It's based on historical occurrences, with a margin of safety added.

The plant is designed to withstand a jolt of 6.5 on the Richter scale - more than 30 times as strong as anything previously recorded anywhere in New Jersey - and would start taking precautionary measures at a Richter reading of 4.

He said the biggest concern would be flooding from a hurricane. The plants sit at about 89 feet above sea level.

Officials would begin shutting water-tight doors if the creek rose to 95 feet above sea level, he said, and shut down the plant if it rose to 124.4 feet above sea level.

Officials with the Union of Concerned Scientists said the accident in Japan also showed that U.S. officials should look at other safety procedures for plants here, including back-up power.

Although they said it was too early to dissect what went wrong in Japan, it seemed clear that the earthquake knocked out the plant's main power. The tsunami did in the back-up generators and on-site batteries had only eight hours of power.

They said that many U.S. plants have only four hours of battery power. "We have hurricanes in New Orleans and ice storms in the Northeast," said David Lochbaum, a nuclear engineer and director of the UCS's Nuclear Safety Program. "That may be an area where we need to shore up."

But industry officials said many more back-up systems are in place, including numerous generators.

U.S. Nuclear Regulatory spokesman Neil Sheehan said that in the last 30 years, all American plants have had to adopt a "station black-out rule" that forced them to confront a series of unlikely scenarios and plan how to respond to them.

Long before the earthquake in Japan, two plants in the region, Limerick and Peach Bottom, were among more than two dozen nationwide identified as needing to take a second look at their plans for seismic activity, based on new data.

Sheehen emphasized this was cautionary.

This region has earthquakes. But "these are the kind of earthquakes that can knock a chimney down," said Jonathan Nyquist, a Temple University geophysicist. "Not the kind that are going to crack reactor vessels."

The largest on record measured 5.2 and 5.3 on the Richter scale. Since the scale has escalating increases, the power of Japan's 9.0 quake was roughly 10,000 times greater.

"Certainly there will be lessons learned coming out of the Japanese events," the NRC's Sheehan said. "Whether or not that leads to revisions at U.S. plants, that remains to be seen."

Source: Philly.com Health News , By Sandy Bauers "Inquirer Staff Writer"