Tag Archives: Nuclear

How seawater could corrode nuclear fuel

Japan used seawater to cool nuclear fuel at the stricken Fukushima-Daiichi nuclear plant after the tsunami in March 2011 — and that was probably the best action to take at the time, says Professor Alexandra Navrotsky of the University of California, Davis.

But Navrotsky and others have since discovered a new way in which seawater can corrode nuclear fuel, forming uranium compounds that could potentially travel long distances, either in solution or as very small particles. The research team published its work Jan. 23 in the journal Proceedings of the National Academy of Sciences.

“This is a phenomenon that has not been considered before,” said Alexandra Navrotsky, distinguished professor of ceramic, earth and environmental materials chemistry. “We don’t know how much this will increase the rate of corrosion, but it is something that will have to be considered in future.”

Japan used seawater to avoid a much more serious accident at the Fukushima-Daiichi plant, and Navrotsky said, to her knowledge, there is no evidence of long-distance uranium contamination from the plant.

Uranium in nuclear fuel rods is in a chemical form that is “pretty insoluble” in water, Navrotsky said, unless the uranium is oxidized to uranium-VI — a process that can be facilitated when radiation converts water into peroxide, a powerful oxidizing agent.

Peter Burns, professor of civil engineering and geological sciences at the University of Notre Dame and a co-author of the new paper, had previously made spherical uranium peroxide clusters, rather like carbon “buckyballs,” that can dissolve or exist as solids.

In the new paper, the researchers show that in the presence of alkali metal ions such as sodium — for example, in seawater — these clusters are stable enough to persist in solution or as small particles even when the oxidizing agent is removed.

In other words, these clusters could form on the surface of a fuel rod exposed to seawater and then be transported away, surviving in the environment for months or years before reverting to more common forms of uranium, without peroxide, and settling to the bottom of the ocean. There is no data yet on how fast these uranium peroxide clusters will break down in the environment, Navrotsky said.

SOURCE:  http://www.physorg.com/news/2012-01-seawater-corrode-nuclear-fuel.html

Investigation findings: Corrosion at Michigan nuclear plant due to stainless steel components

A recent investigation by the Nuclear Regulatory Commission found that the failure of a water pump due to the corrosion of certain kinds of stainless steel components caused an August shutdown of the Palisades nuclear power plant in Covert.

In a news release from his office,Congressman Edward J. Markey, D-Mass., senior member of the House Energy and Commerce Committee, questioned why a substandard steel is still being used for certain plant components.

Here’s what it says:

Despite scientific findings and industry experience reporting its vulnerability to cracks and corrosion, the types of stainless steel –known as 410SS and 416SS – continues to be used in water pumps used to provide cooling water to critical safety-related equipment such as component cooling water, diesel generators, and containment vessel air coolers for nuclear power plants throughout the U.S.

Markey sent a letter querying the NRC about the vulnerability of these metals to corrosion cracking and their continued use despite two decades of failures in nuclear power plants, according to the news release.

Here’s more from the release:

Despite NRC alerting licensees about issues with these pumps, failures continue and licensees have not been required to take any action or even report back to the NRC regarding what they are doing to identify, mitigate or prevent corrosion cracking that could cause component failures.

“They say there was never a good knife made of bad steel. Similarly, you can’t have a safe nuclear reactor made of bad steel,” Markey said. “I am concerned that U.S. nuclear power plants using components made from 410 and 416 steel may be subject to failures of critical safety equipment and at risk of shutdown. NRC must ensure that it requires licensees to take steps to identify and mitigate any corrosion of its components in order to demonstrate that they will perform satisfactorily in service, especially for critical safety-related operations.”

In the letter, Markey asks the NRC to respond to questions that include:

• Which U.S. nuclear power plants currently use 410SS and 416SS components and what are the known uses of 410SS and 416SS?

• Will the NRC undertake a review of 410SS and 416SS steels to determine if additional periodic inspections and mitigation efforts are warranted?

• What regulatory actions will be undertaken in order to assess, require licensee reporting and inspection of, and address problems involved in 410SS and 416SS components?

In March, Congressman Fred Upton pledged support of the nation’s nuclear plants, three of which — Palisades Power Plant in Van Buren County and two at the Cook Nuclear Plant in Berrien County— are in his district, which covers southwestern Michigan.

Upton is chairman of the House Committee on Energy and Commerce.

SOURCE: http://www.mlive.com/news/kalamazoo/index.ssf/2011/12/bum_steel_creates_dangers_at_p.html

U.S Rep. Kucinich seeks NRC hearing about cracks at Davis-Besse

U.S. Rep. Dennis Kucinich (D., Cleveland) asked the Nuclear Regulatory Commission on Monday to hold a public hearing on the cracks in the concrete containment building at the Davis-Besse nuclear power plant 10 miles west of Port Clinton.

In a letter to the chairman of the agency, Mr. Kucinich disputed FirstEnergy’s description of the cracks as “hairline” and as limited to decorative concrete. He said the cracks appear to follow the line of the reinforcing bar, are clearly visible, and run for 30 feet.

He said the cracks could be laid to “concrete carbonation,” the seepage of carbon dioxide through concrete allowing for the corrosion of steel reinforcing bars.

The cracking “seems to indicate a widespread problem that will undermine the structural integrity of the shield building,” Mr. Kucinich wrote to Gregory Jaczko, chairman of the agency.

Mr. Kucinich asked the agency to conduct a public hearing on the cracks before FirstEnergy is allowed to power up the reactor.

A FirstEnergy spokesman said the company has a “root cause team” looking at the problem but that carbonation appears not to be an issue.

“Our testing on a number of concrete samples showed no carbonation on any of the crack surfaces of those that we tested, and [from] our inspections of the rebar, the rebar looks very good and healthy. There was no corrosion of the re-bar,” said spokesman Jennifer Young.

“[Mr. Kucinich’s] letter suggested we weren’t telling the full story. I don’t believe that to be the case. The NRC understands everything we’ve looked at,” Ms. Young said.

She said there are no plans for a hearing and that FirstEnergy continues to work on the crack issue as part of its regular outage. FirstEnergy is shooting for restarting the plant around the end of the month.

The cracks were discovered after a hole was cut in the outer shield building to install a new reactor head. FirstEnergy has submitted to the NRC its finding that the cracks are not a safety hazard and is following up by submitting technical reports to the commission in response to its questions about the matter.

SOURCE: http://www.toledoblade.com/local/2011/11/22/Kucinich-seeks-NRC-hearing-about-cracks-at-Davis-Besse-2.html

Indian nuclear reactor exposed to risk of corrosion

The stagnant coolant water in the reactor vessel and pipes in the first unit of the Kudankulam Nuclear Power Project (KNPP) is giving sleepless nights to scientists and engineers who say the risk of damage to the equipment is increasing each day.

“Water has to be circulating so that the components are not exposed to the risk of corrosion. However, the quality of stagnant water will deteriorate over a period of time, which in turn poses a risk to the reactor components like the primary pipes and the reactor vessel,” said a KNPP official preferring anonymity.

Project work since October has come to a standstill with intensifying protests by villagers on grounds of safety. Roads have been blocked and the local administration has advised the KNPP staff to sit tight inside their homes, fearing violence.

“It is the demineralised water – water in pure form – which is fed into the systems. However, to maintain its purity the water should be circulated as stagnant water will interact with the metal surface and quality will change,” said K S Parthasarathy, former chairman of Atomic Energy Regulatory Board (AERB).

Parthasarathy said there would be a water chemistry group to look at the quality of water used in reactors.

“Water is a hostile fluid. It is not desirable to have stagnant water inside a reactor. However, it is not a serious issue as the number of days that the water remains stagnant is comparatively low,” Parthasarathy added.

“Maintaining the purity of stagnant water is an issue that is facing us. We are not able to check the chemistry of the water that is inside the power plant,” said an NPCIL official.

The helpless officials confined to their homes for nearly a month are hoping that there is no major damage to the reactor components resulting in further delays to the project.

“The systems cannot be stopped and restarted. Decommissioning a reactor is different as one need not bother about the damages the systems would undergo after the plant is stopped,” said the official, who spoke demanding anonymity.

On September 22, the Tamil Nadu government passed a resolution urging Prime Minister Manmohan Singh and the Central government to halt work at Kudankulam till the fear of the people were allayed.

SOURCE: http://ibnlive.in.com/news/kudankulam-reactor-exposed-to-risk-of-corrosion/200806-3.html

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

University of Illinois gets half-million-dollar grant for nuclear research

The U.S. Department of Energy research grant is focused on developing cutting-edge nuclear energy technologies and training and educating the next generation of leaders in the U.S. nuclear industry.

Principal investigator James F. Stubbins, professor and head of nuclear, plasma, and radiological engineering at Illinois, said the UI researchers will look at new materials that can withstand extraordinarily high temperatures and resist corrosion.

This would allow for more efficient use of nuclear energy at the same time it makes the equipment safer from any sort of leak, Stubbins said.

“The idea that we propose is to develop material that could go to very high temperatures for energy in general, but nuclear energy in particular, without corrosion,” he said.

UI professors on the grant are Petros Sofronis and Huseyin Sehitoglu in the Department of Mechanical Science and Engineering; Brent Heuser in the Department of Nuclear, Plasma and Radiological Engineering; Ian Robertson in the Department of Materials Science and Engineering; and Andy Gewirth in chemistry. Stubbins said higher temperatures result in more energy efficiency.

“They’ll last much longer and run at higher temperatures to efficiently convert steam to electricity. In most cases, two-thirds of the energy is lost in the conversion process,” he said.

The end result, Stubbins said, is power that would not increase global warming, because it produces no carbon pollution.

He said the more-efficient processes would create clean energy jobs, while bolstering the U.S. nuclear energy industry — at a time some countries are cutting back on the plants.

In the wake of the earthquake and tsunami in Japan on March 10, Germany announced it will close all its nuclear energy programs by the end of 2022. Italy has followed suit. The UI project could start by Oct. 1.

SOURCE: http://www.news-gazette.com/news/environment/2011-08-12/ui-gets-half-million-dollar-grant-nuclear-research.html

Ancient Roman glass may yield clues to containing nuclear waste

A shipwreck 1,800 years ago in the Adriatic Sea might give scientists at Pacific Northwest National Laboratory better information about how well modern glass might work to contain radioactive waste.

The Department of Energy is building a $12.2 billion vitrification plant at the Hanford nuclear reservation to glassify radioactive waste before it is buried deep in the ground.

The glass, formed from the waste and glass-forming materials, is planned to keep the radioactive waste secure for thousands of years. But until recently, the longest test on a piece of man-made glass holding simulated radioactive waste has been about 25 years.

Thanks to the shipwreck “we can use data points Romans thoughtfully started for us hundreds of years ago,” said Joseph Ryan, a senior scientist at the Department of Energy national laboratory in Richland.

He and scientist Denis Strachan, a laboratory fellow, are taking an atom-by-atom look at ancient glass to see how the glass has held up to corrosion.

Thursday, the two held up a chunk of green glass, marbled with iridescent streaks, that once was the handle of a jar.

It was among the glass that archaeologists believe was carried on the merchant ship Iulia Felix 1,800 years ago. The ship, which measured about 50 feet long, sank six miles off the coast of Grado, scattering glass at the bottom of the Adriatic Sea.

The Iulia Felix is believed to have carried containers of oils and spices, but also a barrel of glass pieces that may have been bound for the port of Aquileia, a center of Roman glass making. The glass pieces would have been recycled there.

Strachan and Ryan also have obtained glass from an archaeological dig at the ancient ruins of Aquileia. The glass is not as well dated, but also could be about 1,800 years old.

The most likely way for modern glass incorporating radioactive waste to corrode and dissolve after it is buried, contaminating the environment, is by exposure to water.

In the Iulia Felix sample, the scientists have pieces of glass that have been sitting in water for 1,800 years. The glass also has some chemical similarities to the glass that will be produced using Hanford’s radioactive waste. Both should contain about 20 percent to 25 percent sodium.

Strachan traveled to Italy to get the glass from the Aquileia archaeological excavation. He didn’t want just another piece of ancient glass, but glass still buried in the soil so researchers could look at how the glass dissolved and material from the glass moved into and through the soil.

The PNNL researchers have used a focused ion beam to machine minute cones out of the iridescent streaks in the glass from the Iulia Felix to look at samples measuring about 20 nanometers, or a ten-thousandth the diameter of a human hair. The iridescent streaks are caused by the reflection of light off the areas where the glass has corroded at the points the handle was attached to the jar.

The samples are being studied with an atom probe at the Environmental Molecular Sciences Laboratory on the PNNL campus, which can show an atom-by-atom picture of the structure of the iridescent glass. Images show individual atoms arranged in layers of magnesium and oxygen.

The ancient glass wasn’t designed to be durable over 1,800 years, but it has held up well, Strachan said. And the glass planned to incorporate nuclear waste can be designed to be even more durable, he said.

But the study will put data to that assertion. It will provide a mathematical look at how glass dissolves that can be used to confirm and refine computer models now used to predict the performance of glass.

“We want to show if we put (waste) glass underground and let it sit for millions of years, the public will be safe,” Strachan said.

The study, which is part of international research on glass corrosion, is being paid for by the Department of Energy.

In addition to information about glassified waste from national defense projects, such as plutonium production at Hanford, DOE also is interested in information that could be useful if the nation decides to reprocess commercial nuclear fuel and then glassify the waste from reprocessing.

The project also could help archaeologists. By learning more about the rate of glass corrosion, archaeologists may be better able to date ancient glass.

SOURCE: http://www.thenewstribune.com/2011/08/12/1779898/ancient-roman-glass-may-yield.html#ixzz1UoYBBnji

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.”


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