Tag Archives: Associated Press

Nuclear Regulatory Commission responds to rare East Coast earthquake

When an earthquake hit Virginia Tuesday afternoon, nuclear power plants up and down the East Coast — including Exelon Nuclear’s Limerick Generating Station — began assessing if damage had occurred.

Part of the problem, however, may be that the place an earthquake is most likely to cause damage is also the place the hardest to inspect — underground.

Making that scenario more worrisome is a June investigative report by the Associated Press which found that as the nation’s nuclear fleet ages, much of its underground infrastructure, exposed to corrosion – and is constantly exposed to moist conditions, may be deteriorating even faster.

Assessing earthquake damage is not a simple operation given that “each plant has unique design specifications for seismic resistance,” according to Nuclear Regulatory Commission spokesman Neil Sheehan.

Called its “design basis,” each plant is “built to withstand the largest historical earthquake in the area, with additional margin on top of that,” Sheehan wrote in an email answering questions from Journal Register News Service.

Sheehan noted that in the wake of the Mineral, Va. tremblor, “walk down” or visual inspections “of key infrastructure at each facility” at all nuclear plants were conducted both by plant personnel and independently by the resident NRC inspectors at each plant.

“No structural damage has been identified at any of the affected plants,” he wrote.

But while visual inspections may have found no damage, any underground damage not evident to the naked eye could only be identified by a change in readings for pipes, gauges or underground valves, according to Sheehan.

“Any significant impacts on buried piping would be readily noticeable via changes in flows. Also, plant owners are required to perform flow tests on safety- and non-safety-related piping at regular intervals,” Sheehan wrote in his email.

“Whether those checks would need to be accelerated in light of yesterday’s earthquake will have to be determined,” he added.

Perhaps that determination will be influenced by the AP report which found underground leaks “sometimes go undiscovered for years, the AP found.”

The AP found that leaks of water laced with traces of tritium, a radioactive form of hydrogen, have been found at 48 of 65 nuclear sites “repeatedly at many of them.”

Although some of those leaks occurred at plants owned by Exelon, no such leak has ever been reported at the Limerick Generating Station.

However, “slightly elevated levels of tritium” were found in six water samples taken from on-site wells at Limerick as well as in one surface water sample according to a study released in 2006. However, the company statement issued at the time said those higher levels are the result of “historic releases.”

In other words: surface spills, not underground leaks.

The “historic releases” were described by a company spokesperson as four “unplanned liquid releases” of tritium that took place “over the past 20 years.”

The tritium was the result of spills, not underground leaks, that had all occurred “in isolated areas on the plant property where you don’t normally find tritium” and had all been reported to the NRC and to the Pennsylvania Department of Environmental Protection.

All the spills were “within our permitted discharge levels” and there were no fines or violations associated with them and the spokesperson said the tests showed none of Limerick’s underground systems were leaking in 2006.

But there were leaks at three Illinois nuclear plants owned by Exelon, one of them from an underground source that went on for four years.

The AP reported that “nuclear operators have failed to stop an epidemic of leaks in pipes and other underground equipment in damp settings. The country’s nuclear sites have suffered more than 400 accidental radioactive leaks during their history, the activist Union of Concerned Scientists reported in September.

“Plant operators have been drilling monitoring wells and patching hidden or buried piping and other equipment for several years to control an escalating outbreak.

“Here, too, they have failed. Between 2000 and 2009, the annual number of leaks from underground piping shot up fivefold, according to an internal industry document obtained and analyzed by the AP.”

The AP investigation also reported “many of the pipes or tanks have been patched, and contaminated soil and water have been removed in some places. But leaks are often discovered later from other nearby piping, tanks or vaults. Mistakes and defective material have contributed to some leaks. However, corrosion — from decades of use and deterioration — is the main cause. And, safety engineers say, the rash of leaks suggest nuclear operators are hard put to maintain the decades-old systems.”

All of which occurred, presumably, without the added stress of an earthquake on aging materials exposed to corrosion.

In addition to publishing an assessment of NRC investigation and enforcement following incidents at plants in 2010, The Union of Concerned Scientists recently issued a set of recommendations for ways NRC could improve safety at the nations 104 nuclear reactors.

Among those recommendations:

• “The NRC should require plant owners to use multiple inspection techniques to ensure detection of any degradation in aging, high-risk equipment.

• “The NRC should require plant owners to periodically inspect equipment outside the scope of normal inspections, both to determine whether that scope is appropriate and to detect problems before safety margins are compromised.”

SOURCE: http://timesherald.com/articles/2011/08/24/news/doc4e55b13c42b0c638332971.txt?viewmode=fullstory

75 percent of US nuclear sites have corrosion issues — leaking tritium

BRACEVILLE, Ill. (AP) – Radioactive tritium has leaked from three-quarters of U.S. commercial nuclear power sites, often into groundwater from corroded, buried piping, an Associated Press investigation shows.

The number and severity of the leaks has been escalating, even as federal regulators extend the licenses of more and more reactors across the nation.

Tritium, which is a radioactive form of hydrogen, has leaked from at least 48 of 65 sites, according to U.S. Nuclear Regulatory Commission records reviewed as part of the AP’s yearlong examination of safety issues at aging nuclear power plants. Leaks from at least 37 of those facilities contained concentrations exceeding the federal drinking water standard – sometimes at hundreds of times the limit.

While most leaks have been found within plant boundaries, some have migrated offsite. But none is known to have reached public water supplies.

At three sites – two in Illinois and one in Minnesota – leaks have contaminated drinking wells of nearby homes, the records show, but not at levels violating the drinking water standard. At a fourth site, in New Jersey, tritium has leaked into an aquifer and a discharge canal feeding picturesque Barnegat Bay off the Atlantic Ocean.

Any exposure to radioactivity, no matter how slight, boosts cancer risk, according to the National Academy of Sciences. Federal regulators set a limit for how much tritium is allowed in drinking water, where this contaminant poses its main health risk. The U.S. Environmental Protection Agency says tritium should measure no more than 20,000 picocuries per liter in drinking water. The agency estimates seven of 200,000 people who drink such water for decades would develop cancer.

The tritium leaks also have spurred doubts among independent engineers about the reliability of emergency safety systems at the 104 nuclear reactors situated on the 65 sites. That’s partly because some of the leaky underground pipes carry water meant to cool a reactor in an emergency shutdown and to prevent a meltdown. Fast moving, tritium can indicate the presence of more powerful radioactive isotopes, like cesium-137 and strontium-90.

So far, federal and industry officials say, the tritium leaks pose no health or safety threat. Tony Pietrangelo, chief nuclear officer of the industry’s Nuclear Energy Institute, said impacts are “next to zero.”

EAST COAST ISSUES

One of the highest known tritium readings was discovered in 2002 at the Salem nuclear plant in Lower Alloways Creek Township, N.J. Tritium leaks from the spent fuel pool contaminated groundwater under the facility – located on an island in Delaware Bay – at a concentration of 15 million picocuries per liter. That’s 750 times the EPA drinking water limit. According to NRC records, the tritium readings last year still exceeded EPA drinking water standards.

And tritium found separately in an onsite storm drain system measured 1 million picocuries per liter in April 2010.

Also last year, the operator, PSEG Nuclear, discovered 680 feet of corroded, buried pipe that is supposed to carry cooling water to Salem Unit 1 in an accident, according to an NRC report. Some had worn down to a quarter of its minimum required thickness, though no leaks were found. The piping was dug up and replaced.

The operator had not visually inspected the piping – the surest way to find corrosion- since the reactor went on line in 1977, according to the NRC. PSEG Nuclear was found to be in violation of NRC rules because it hadn’t even tested the piping since 1988.

Last year, the Vermont Senate was so troubled by tritium leaks as high as 2.5 million picocuries per liter at the Vermont Yankee reactor in southern Vermont (125 times the EPA drinking-water standard) that it voted to block relicensing – a power that the Legislature holds in that state.

In March, the NRC granted the plant a 20-year license extension, despite the state opposition. Weeks ago, operator Entergy sued Vermont in federal court, challenging its authority to force the plant to close.

At 41-year-old Oyster Creek in southern New Jersey, the country’s oldest operating reactor, the latest tritium troubles started in April 2009, a week after it was relicensed for 20 more years. That’s when plant workers discovered tritium by chance in about 3,000 gallons of water that had leaked into a concrete vault housing electrical lines.

Since then, workers have found leaking tritium three more times at concentrations up to 10.8 million picocuries per liter – 540 times the EPA’s drinking water limit – according to the New Jersey Department of Environmental Protection. None has been directly measured in drinking water, but it has been found in an aquifer and in a canal discharging into nearby Barnegat Bay, a popular spot for swimming, boating and fishing.

SOURCE: http://gazettenet.com/2011/06/17/75-percent-of-nuke-sites-have-leaked-tritium