Fort Calhoun: A Status Update

Lara Uselding
Public Affairs Officer, Region IV
 

The NRC will hold a public meeting March 27 to discuss the status of the Fort Calhoun nuclear plant, located 19 miles north of Omaha. As many know, the plant has been shut down since April 9, 2011, for a refueling outage. The outage was extended due to historic flooding along the Missouri River followed by an electrical fire that led to an “Alert” declaration and further restart complications.

We’d like to bring readers up to speed on where we are since January’s blog update and share four new updates.

First, the NRC recently revised the Confirmatory Action Letter (CAL) we originally issued in June 2012, outlining actions Omaha Public Power District (OPPD) had agreed to do before restarting the plant. The revisions added three categories to the restart checklist – OPPD will address containment internal structure issues, the use of Teflon seals on electrical cables passing through containment, and several event reports involving recently identified equipment problems.

This was followed by an update to the detailed 450+ action item list known as the basis document to reflect the three new CAL categories. After conducting independent verification of OPPD’s work, the NRC has closed more than 100 items on the basis document list, although none of the 18 restart checklist categories have been closed.

fcsThe third update is that a 15-member NRC inspection team led by a veteran Senior Resident Inspector Greg Warnick, stationed at another plant, has been on site conducting a thorough inspection and independent verification of Fort Calhoun’s current safety status. The team inspection will provide the NRC a real sense on how much progress OPPD has made in preparing plant systems, structures, components, people and processes for restart. The inspectors are using the basis document’s 450+ items as their guide.

Fourth, an inspection report issued yesterday, lists two NRC-identified issues, including a failure by OPPD to get NRC approval before making changes to the plant’s flood protection strategy. Inspectors also identified that OPPD failed to address a 2012 violation involving six sluice gates and motors that control the flow of water from the Missouri River into the plant’s cooling system. By not following the process to classify these sluice gates as safety related, the intake structure may not properly protect the cooling water system and pumps during a flood.

The public is encouraged to join us in Omaha for the meeting where the NRC staff will be available to answer questions about these topics.

Deconstructing the Decommissioning Process

Dave McIntyre
Public Affairs Officer
 

Duke Energy’s decision to shut down the Crystal River 3 reactor in Florida rather than pay for expensive repairs to its containment dome has focused attention once more on the lengthy process for decommissioning nuclear power plants. Since Dominion Nuclear’s announcement last year that it will shutter its Kewaunee plant in Wisconsin, the country now has two reactors entering this process.

crDuke took the first step on Feb. 20, when it gave the NRC its official certification that it had permanently ceased operations at Crystal River 3 and permanently removed the fuel from the reactor. Those certifications effectively changed the plant’s operating license to a “possession only” license – in other words, the company is no longer permitted to load fuel into the reactor vessel and operate the plant.

After these initial certifications, the process can be quite slow. Duke will have up to two years to develop and submit its decommissioning plan – officially called the post-shutdown decommissioning activities report, or PSDAR in NRC-speak. The report will include a description and schedule for decommissioning activities, their estimated cost, and a discussion of why any anticipated environmental impacts have already been reviewed in previous environmental reports on the plant.

Once the NRC receives the PSDAR, we will publish it for public comment and conduct a public meeting near Crystal River to explain the decommissioning process. Duke will not be able to conduct any major decommissioning activities until 90 days after NRC receives the PSDAR.

Under NRC regulations, Duke can take up to 60 years to complete the process, from cessation of operations to final decommissioning and termination of license. Why so long? There are actually two advantages: Radioactivity decays over time, making the final cleanup easier; and the company’s decommissioning trust fund continues to grow. This stage of decommissioning is called SAFSTOR, as the company maintains the shuttered plant in safe storage until final cleanup begins.

Throughout this process, Duke will be able to use some of its decommissioning funds. It can spend up to 3 percent of the fund on decommissioning planning as it develops the PSDAR, and up to 20 percent to maintain and monitor plant safety during the SAFSTOR period. NRC limits use of the funds to ensure that enough money remains to complete cleanup and follow the process through to license termination.

The NRC requires Duke to clean up the site so that residual radiation is quite low – specifically, that no person on the site would receive a dose above 25 millirem per year. (In comparison, the average American receives 310 millirem per year from natural radiation, and the dose from a single chest X-ray is about 10 millirem.) At least two years before Duke reaches that point, it must submit a license termination plan, detailing the final steps. NRC inspectors will verify that the site has been decontaminated to the NRC’s requirements. Duke will then ask the NRC to terminate the license, or modify it to apply only to a spent fuel storage facility, if needed.

One popular question is the cost of decommissioning a nuclear power plant. Estimates vary, and of course it has been several years since a plant has been decommissioned, but the NRC estimates that the costs generally range from $300-400 million. This estimate applies only to NRC-mandated activities – in other words, reaching the radiological criteria. Dismantling other parts of the plant (such as support buildings) would cost extra, so the company’s estimate might be higher.

Throughout the entire decommissioning process, the NRC’s objective is to protect public health and safety while ensuring that the site is cleaned up to our requirements.

For more information, NRC regulations on decommissioning are 10 CFR 50.82 and 10 CFR 20, Subpart E.

Additional Note: There are two other possible methods for decommissioning. DECON involves active decontamination of the site, either immediately after operations cease or after a period of SAFSTOR. The third, ENTOMB, is just what it sounds like – radioactive contaminants are permanently encased on site in structurally sound material such as concrete and appropriately maintained and monitored until the radioactivity decays to a level permitting restricted release of the property. To date, no NRC-licensed facilities have requested the ENTOMB option.

Thermal Hydraulics: Heat, Water, Nuclear Power and Safety

Scott Krepel
Reactor System Engineer
 

One of the most important safety questions in a nuclear power plant is: Can you cool the very hot nuclear fuel in an accident when normal cooling is disrupted? The scientific field best equipped to answer this question is called “thermal hydraulics.”

bwrThe first part of the term, “thermal,” relates to heat transfer, such as the movement of heat from the burner on a stove to the water in a pot via the metal of the pot. The second part, “hydraulic,” relates to the flow of a fluid such as water. The combination, “thermal hydraulics,” can be applied to systems where both the flow of fluid and the transfer of heat are important – such as a nuclear power plant.

I work in the NRC’s Office of Nuclear Regulatory Research as part of a team dedicated to expanding our understanding of thermal hydraulics and applying that understanding in nuclear power plant safety. Over time, we’ve put much effort into incorporating existing knowledge into the NRC’s thermal hydraulics computer simulation program, TRACE. This program allows NRC staff to construct computer models of the cooling systems of a nuclear power plant and then simulate accidents such as pipe breaks (but not wildly improbable events such as the considerable destruction caused near the end of a typical superhero action movie).

TRACE is constantly being pushed to become more accurate, reliable and versatile. Universities and test facilities around the world are conducting experiments and accident simulations to collect real-world data that can be used to determine TRACE’s ability to accurately predict specific phenomena. We use the outcomes to update the program as needed to make it more accurate and to better capture certain phenomena.

Sometimes, new safety issues may result in further investigation of certain scenarios and further evolution of TRACE. Ultimately, the goal of this work within the research arm of the NRC is to continuously expand our understanding of situations which may impact the cooling of the nuclear fuel. This knowledge can then be used to ensure that the public and the environment are protected in the unlikely event of an accident at an U.S. nuclear power plant.

Fort Calhoun Nuclear Plant – A 2013 Update

Lara Uselding
Public Affairs Officer
Region IV
 

fcsAs we turn the page on a new year, the NRC is watching closely as the operators of the Fort Calhoun nuclear plant, located in Omaha, Neb., are working around the clock in hopes of returning the plant to service. It remains to be seen if the NRC is convinced the efforts of the Omaha Public Power District’s (OPPD) are sufficient.

The plant has been powered down since April 9, 2011, for a refueling outage. The outage was extended due to historic flooding along the Missouri River followed by an electrical fire that led to an “Alert” declaration and further restart complications.

On Jan. 8, OPPD officials and the NRC Fort Calhoun Oversight Panel members met before the five-member NRC Commission to discuss the current plant status. Positive change is on the horizon. “They [OPPD] are looking at problems with a different set of eyes today,” said Mike Hay, NRC Branch Chief and panel member. Some NRC Commissioners also noted the efforts by OPPD management to turn things around. It is also clear more work needs to be done.

In November 2012, the NRC issued a detailed inspection plan listing some 450 items that require attention, inspection, and resolution. Many of these items are subsets of the familiar issues that have been reported over the past two years including the breaker fire, flood strategy concerns, containment penetrations, and containment internal structures issues.

In 2013, there will be numerous NRC inspectors carrying out a very rigorous inspection schedule. A five-member team has already been on site for two weeks to independently verify results from a third-party safety culture assessment done last year. As part of the inspection, NRC held focus group interviews with plant works to assess the current climate and help the NRC understand how in tune management is with staff. Later in February, these results will be used to fuel a second, larger team inspection to fully assess human performance and safety culture at Fort Calhoun.

There is more to come. There will be an announcement soon with details for the next public meeting in Nebraska. The staff will continue to post updates and helpful information to the Fort Calhoun specific Web site.

NRC Hosts Webinar on Palisades Leaks

palisades_small

Viktoria Mitlyng
Senior Public Affairs Officer
Region III
 

We gathered at the NRC’s Region III office near Chicago on a recent Saturday morning to continue our dialogue with the public about the Palisades nuclear plant. We decided to host our second webinar on this plant on a Saturday in response to a request from members of the public to hold it at a time when people aren’t at work.

Close to 100 people listened to the NRC’s presentation by four representatives of the Region III staff and asked questions on a wide range of questions on recent problems at Palisades.

The purpose of the webinar was to talk about the NRC’s regulations on a specific category of leaks – including the leaks that occurred at Palisades in 2012 – and the NRC’s response to these leaks. They are called “through-wall” leaks because they come through the wall of pipes and other plant components important to safety.

Resident inspectors stationed at every nuclear plant in the country continuously monitor any such leaks making sure they are properly understood and handled. Leaks that have no safety impact are not regulated by the NRC.

NRC’s regulations on through-wall leaks are based on the safety significance of the affected equipment. Leaks from the pressure retaining boundary of the reactor coolant system are not allowed and must be fixed right away. Other types of leaks may not require immediate repair but must be fixed before they have a negative impact on plant safety.

We talked about four through-wall leaks identified at Palisades last year; one of these was discovered by an NRC Resident Inspector during a routine daily inspection. Even though these leaks did not compromise plant safety, they concerned us because of their frequency. The agency decided to commit additional resources this year to evaluate these leaks and determine whether they represent a weakness in the plant’s maintenance program.

Three of the four leaks at Palisades have been fixed. The remaining leak from a refueling water tank is closely monitored and will be repaired according to NRC regulations.

We informed the public when the leaks at Palisades were discovered even though the NRC doesn’t normally make public notifications on leaks of very small safety significance. This was done in response to requests from many people to be informed about such issues at the plant.

We will continue the high level of engagement with the public near the Palisades plant to meet the agency’s goal of openness and transparency. Additional webinars on reactor vessel head embrittlement and environmental monitoring are already in the works. In addition, the NRC staff will have a booth at the Garden and Leisure Show in Benton Harbor, Mich., March 15-17.

A Fire at South Texas Project – How the NRC Responded

Victor Dricks
Senior Public Affairs Officer
Region IV
 
The Region IV Incident Response Center during an emergency exercise last month.
The Region IV Incident Response Center during an emergency exercise last month.

At 4:40 p.m. Central Time Tuesday, officials at the South Texas Project nuclear power plant near Bay City, Texas, notified the NRC’s Operations Center that a fire had broken out in the main transformer of Unit 2, causing an automatic shutdown. Unit 1 was unaffected and continued to operate at full power.

As designed, the plant’s emergency diesel generators energized to power safety-related equipment. All four auxiliary feedwater pumps started as required to supply power to the plant’s steam generators for cooling. However, power to non-safety related electrical buses was lost, cutting off power to the plant’s reactor coolant pumps. As part of the plant’s design, natural draft circulation continued to cool the plant’s shutdown reactor to remove decay heat.

The plant declared an Unusual Event – the lowest of four categories of nuclear emergency — due to the transformer fire at 4:55 p.m. The plant’s on-site fire brigade responded and quickly extinguished the blaze, so no off-site assistance was required.

The NRC’s resident inspector, who was on-site at the time, responded to the event by going to the plant’s control room to observe the licensee’s response to the event. The NRC’s Region IV Office in Arlington, Texas, activated its Incident Response Center to monitor the event.

There were no personnel injuries and no radiological releases were reported. The Unusual event was terminated at 7:47 p.m., although the NRC’s resident inspector remained onsite until about midnight.

As part of its ongoing oversight, the NRC will monitor the licensee’s follow-up actions. These include identification of the cause of the transformer fire; a review of the behavior of the plant’s electrical protection systems; and various repair activities.

“Overall, from what we now know, plant operators responded well to the event,” said Acting Deputy Regional Administrator Steve Reynolds. “The NRC will conduct an independent and comprehensive assessment of this incident as part of its oversight process.”