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Category Archives: Operating Reactors

Update on Quality Assurance Issues in France

17 Comments Posted by on January 10, 2017

David McIntyre
Public Affairs Officer

Today, the NRC is releasing information about large reactor components supplied to U.S. nuclear plants by AREVA’s Creusot Forge in France. This information includes the names of the plants and the reactor components involved.

This blog post discusses the information as well as the NRC’s actions related to ongoing French investigations into potential defects and problems with quality assurance documents regarding the parts’ manufacture.

We are confident at this time that there are no safety concerns for U.S. nuclear power plants raised by the investigations in France. Our confidence is based on the U.S. material qualification process, preliminary structural evaluations of reactor components under scrutiny in France, U.S. material aging-management programs, our participation in a multinational inspection of Creusot Forge, and information supplied by AREVA about the documentation anomalies. Also, the components supplied to U.S. plants have performed well and inspections during their operating life have revealed no safety issues.

Because there are no immediate safety concerns, there is no justification for the NRC to order plants to shut down and inspect components, as some groups have suggested. Should new information raise a specific safety concern, the agency will take appropriate action.

The information released today ML17009a275 was provided to the NRC on Dec. 15 at our request by AREVA, a multinational manufacturer of nuclear plant components.  We informed AREVA on Dec. 30 of our intent to make the information public (ML16364A034). Attachment A lists components with forgings from Creusot Forge supplied to 17 U.S. reactors at 13 sites, directly by AREVA or through third-party vendors. The components are mostly replacement reactor vessel heads, replacement steam generator components or pressurizers. AREVA clarified the list in letters dated Jan. 9 and Jan. 10, which are included in the information.

We posted a piece last June about the investigation by the French Nuclear Safety Agency, ASN, into AREVA’s Creusot Forge. Here is an update:

There are two separate, but related, issues to the investigation in France. The first is called “carbon segregation,” a condition that in certain circumstances could create local areas of reduced toughness in large forged components of nuclear plants. The second is a series of anomalies discovered in the quality assurance documentation of components manufactured at Creusot Forge.

Carbon segregation occurs naturally during the casting of steel ingots. Carbon molecules concentrate as newly forged ingots cool. Most of this excess carbon is cut away and discarded before the actual plant components are formed, but some processes leave small areas of elevated carbon content near the component’s surface. NRC regulations and code requirements by the American Society of Mechanical Engineers account for this condition. Higher-than-expected carbon segregation has been discovered on some reactor components in France that were manufactured using a particular process, though there are no indications it would exceed U.S. limits. We’ve asked AREVA if any components supplied to U.S. reactors were manufactured using that same process, and we expect the company’s answer soon.

While investigating the carbon segregation issue, ASN discovered anomalies in the documents describing how components were manufactured at Creusot Forge. This probe, launched last May, has since expanded to include a review of documents dating back to 1965. (AREVA acquired Creusot Forge in 2006.)

Two NRC inspectors participated in an inspection of the Creusot Forge facility in late November/early December. The inspection team included inspectors from France, the United Kingdom, Finland, China and Canada, and was conducted under the Multinational Design Evaluation Programme, which facilitates information exchanges among nations. During the inspection, AREVA reported that some files on components supplied to U.S. nuclear plants contained anomalies. The company said the anomalies presented no apparent safety concerns.

The NRC inspectors conducted a preliminary review of records for three U.S. plants and agreed that AREVA had made a reasonable assessment of no safety concerns.

The ASN, which led the inspection, is expected to issue a report on its findings in the next several weeks. Meanwhile, AREVA filed an interim report to the NRC on Dec. 7 (ML16344A120), providing more information about document anomalies affecting some U.S. plants. AREVA said it had notified its U.S. customers (including nuclear power plants and vendors) of the documentation issues and its assessment that there are no related safety concerns. The company said it expects to complete its evaluation of Creusot Forge’s documentation processes for U.S. plants by June 30, 2017.

We are not taking this issue lightly. Complete and accurate documentation provides assurance that components were forged to the proper procedures and specifications. As the investigation continues, we remain alert to any indication that the documentation irregularities at Creusot Forge might call into question the safety of these components and U.S. nuclear plants.

 

Operating Reactors , ,

Getting Ready for Winter Looks Much Like Preparing for Hurricanes

5 Comments Posted by on January 3, 2017

Neil Sheehan
Public Affairs Officer
Region I

coldweatherAt first glance the blizzard that pounded the upper Midwest on Christmas weekend – or the winter storm that hit New England over New Year’s — doesn’t seem to have much in common with the hurricanes that hit the Gulf Coast or Eastern Seaboard during the hot summer months.

But from our perspective, they do.

NRC regulations requires that U.S. nuclear power plants be ready for all kinds of weather conditions, and that extends to winter storms.

The preparations take many forms. Here are some of the key activities:

  • Plant operators keep close tabs on approaching storms via weather forecasting services. Storm watches or warnings would clearly attract attention.
  • As a storm draws closer, information gathered from the facility’s meteorological towers is assessed. These data points would include wind speed/direction and snowfall rates. Specific conditions, such as wind speeds exceeding a pre-designated threshold, can result in operators starting to shut down the reactor, or reactors, at a plant site.
  • Prior to a storm arriving in the area, plant personnel would conduct visual inspections of plant grounds. They would check that there were no loose items that could be propelled by strong winds and potentially damage equipment.
  • Workers would also ensure that fuel tanks for emergency diesel generators were filled. These generators can provide back-up power for plant safety systems should the local electrical grid go down.
  • Plans would also be developed to keep the plant appropriately staffed until the storm had passed. This might mean providing cots and food for employees unable to get home due to the weather conditions.

Amid all of these preparations, the NRC Resident Inspectors assigned to each plant would follow the progress of these activities while also tracking expected conditions at the plant. They, too, could be asked to stay at the facility until the storm had passed.

The old adage that success is “90 percent preparation and 10 percent perspiration” is one taken seriously when wicked weather is bearing down.

 

Emergency Preparedness and Response, Operating Reactors , , , ,

Five Questions with Rick Hasselberg

14 Comments Posted by on December 20, 2016

Rick Hasselberg is a Senior Emergency Response Coordinator with the NRC’s Office of Nuclear Security and Incident Response.

  1. How would you briefly describe your role at the NRC?

5 questions_9with boxI manage the NRC’s Reactor Safety Team. If an emergency occurs at a nuclear power plant, my team is responsible for assessing nuclear facility conditions, predicting future conditions, and recommending actions the NRC might take to help protect public health and safety. I am responsible for recruiting, training, and continuously challenging the expertise and response readiness of one of the most respected emergency response organizations in the world.  What could be better than that?

  1. What is your foremost responsibility at work?

I think about emergencies. While 99 percent of the people working at the NRC are working hard to ensure that appropriate safety measures are in place, I work under the assumption that any of those safety measures could possible fail and that it’s time to get busy.  (The more I think about the things that might happen, the less surprised I will be if they do.

  1. What is your most significant challenge in the workplace?

rickh_fixedI struggle with competing demand for the agency’s best and brightest employees.  I must ensure that NRC will able to maintain a pool of experienced, qualified response team members who can be pulled away from their regular duties to train, exercise and, if ever needed, to respond to an actual emergency event.

  1. What do you consider one of your most notable accomplishments at the NRC?

I joined the NRC in late 1979, in the months following the Three Mile Island Accident. During that period, the NRC was under considerable pressure to improve both its internal training programs and its external public information (outreach) programs. I contributed significantly to both programs, introducing multimedia production techniques (film, video, and 35mm slides) for improving internal technical training, and I created and presented a highly acclaimed, day-long Nuclear Power and Radiation seminar that NRC presented to news media representatives throughout the United States. I was credited with helping to re-establish NRC credibility with the news media.

  1. What is one quality of the NRC that more people should know?

This agency has a lot of very smart, very talented people who really care about their role in serving the nation. I’m very proud to serve with them.

Five Questions is an occasional series in which we pose the same questions to different NRC staff members.

 

 

Emergency Preparedness and Response, Operating Reactors , , , ,

NRC’s Requirements Following Entergy’s Announcement Palisades Will Cease Operation

9 Comments Posted by on December 12, 2016

Viktoria Mitlyng
Senior Public Affairs Officer
Region III

Entergy announced last week it would permanently shut down its Palisades Nuclear Plant on October 1, 2018. The facility, located in Covert, Mich., has been in operation since 1971 and is licensed to operate until 2031.

palisades_smallThe NRC was not involved in the decision, which the company said was based on business and financial factors. Our single focus as an independent regulator is on the safety of nuclear plants, the public and the environment.

However, once any announcement about closure is made, the NRC becomes engaged and the company has to meet our requirements for permanently shutting down an operating reactor.

The first step in this process requires Entergy to make a written Certification of Permanent Cessation of Operations to the NRC within 30 days from announcing its decision to permanently take the plant off line.

Should Entergy decide to continue operating the plant beyond the date stated in the certification, it would have to notify the NRC in writing.

As long as the plant is operating, we will continue to independently verify Palisades is meeting NRC’s stringent requirements. These requirements will remain in place until all fuel is removed from the reactor and the NRC has the company’s certifications of permanent cessation of operation and permanent fuel removal. At that point in the process, Entergy is no longer authorized to put new fuel into the reactor or resume plant operation.

The plant then enters the NRC’s well-established decommissioning process  geared towards ensuring the continued safe use of nuclear material, and the safety of nuclear workers and the public. Decommissioning must be completed within 60 years of the plant ceasing operations.

Nuclear plant operators are required to plan for the ultimate decommissioning of the plant before it begins operations by establishing and maintaining a dedicated decommissioning fund. These funds – created to ensure there will be sufficient money to pay for a plant’s radiological decommissioning — cannot be used for any other purpose unless the NRC grants an exemption.

Operating plants must maintain the required levels established by the NRC  and certify that there is reasonable assurance there will be adequate decommissioning funds, at least every two years while the plant is operating and more frequently after it ceases operations. The NRC reviewed the decommissioning funding status report  for Palisades in 2015 and found that it met our requirements.

Decommissioning, Operating Reactors , , , ,

REFRESH — Where There’s Steam, There’s … a Steam Generator

3 Comments Posted by on December 1, 2016

Kenneth Karwoski
Senior Advisor for Steam Generators

refresh leafWhen the NRC talks about “steam generators,” we’re not talking about teakettles. Steam generators provide vital technical and safety functions at many U.S. nuclear power plants.

In the United States, steam generators are only found in pressurized-water reactors, one of the two types of U.S. reactors. There can be two to four steam generators for each reactor unit. The generators mark the spot where two closed loops of piping meet. The first loop sends water past the reactor core to carry away heat, and this loop is at such high pressure that the water never boils. The second loop is at a lower pressure, so the water in this loop turns to steam and runs the plant’s turbine to generate electricity.

The steam generator’s main technical job is to let the first loop pass its heat to the second loop as easily as possible. To do this, a steam generator packs thousands of small tubes closely together, allowing the maximum area for heat to pass through the tubes and into the second loop’s water.

At the same time, the steam generators provide an important safety barrier – the first loop can contain radioactive material, so the tubes must keep the two loops of water separate. NRC rules require plants to closely monitor the second loop and immediately shut the reactor down if a tube leak exceeds very strict limits.

pwr[1]The NRC’s rules for inspections, maintenance and repair of steam generator tubes help ensure the tubes continue providing the safety barrier. If an inspection shows a tube is starting to get too thin, the plant will repair or even plug a tube to maintain safety.

Steam generator tube material has improved over time. The first steam generators had tubes made from a type of stainless steel that experience showed could be corroded by the chemicals, temperatures and pressures in the first and second loop. Over time, plants have replaced those steam generators with ones using more advanced alloys that are less likely to corrode.

Steam generator replacement only happens when the reactor is shut down for refueling, and plant owners bring in hundreds of specialized workers to safely remove the old generators and install the new ones. The old generators have to be safely disposed of as low-level radioactive waste.

REFRESH is an occasional series where we revisit previous posts. This first ran in July 2013.

Operating Reactors , , , ,

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