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

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.

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

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.

When A Plant Changes Hands

Neil Sheehan
Public Affairs Officer
Region I

FitzPatrickTowerViewIn February, Entergy announced plans to permanently shut down the James A. FitzPatrick nuclear power plant on Jan. 27, 2017. However, there are indications – based on recent negotiations between Entergy and Exelon – that the facility may not cease operations after all.

On Aug. 9, Exelon announced it had reached a deal to purchase the Scriba (Oswego County), N.Y., boiling-water reactor from Entergy for $110 million. This agreement occurred after the New York State Public Service Commission approved Zero Emission Credits, or subsidies, which will help upstate N.Y. nuclear plants stay online amid historically low energy prices.

Challenging market conditions had earlier prompted Entergy to announce the plant’s closure. The NRC in 2008 had approved a renewal of FitzPatrick’s initial 40-year operating license, extending it until October 2034.

Before the sale of the plant can be completed, the transaction will undergo reviews by the NRC, as well as other regulatory agencies. NRC staff will evaluate Exelon’s technical and financial capabilities to ensure the plant’s safe operation and to provide reasonable assurance that adequate funding is available to safely decommission the unit after the final shutdown has occurred.

Exelon currently owns and operates 22 reactors at 13 plant sites in the U.S. The company also runs Fort Calhoun under a contract with the Omaha Public Power District.

We will publish on our website and in the Federal Register a notice of having received the license transfer application, dated August. 18, and the opportunity to request a hearing on the proposal. As for the process itself, such reviews generally take from six months to a year. For example, when the FitzPatrick operating license was transferred from the New York Power Authority to Entergy in 2000, the review was completed in about half a year.

As a footnote, Exelon already owns the Nine Mile Point nuclear power plant, which is located next-door to FitzPatrick.

Part II: How the NRC Uses a Defense-in-Depth Approach Today to Protect the Public

Mary Drouin
Senior Program Manager
Division of Risk Assessment, Performance and Reliability Branch

Defense-in-depth is a central theme in the NRC’s regulatory oversight of the nuclear power industry. As our agency historian, Tom Wellock, discussed in Monday’s post, the concept of defense-in-depth emerged during the trench warfare of World War I. The idea of multiple lines of defense was applied to nuclear safety in the 1950s as the leading concept for protecting the public from the consequences of a nuclear reactor accident.

The NRC’s predecessor agency, the U.S. Atomic Energy Commission, spelled out defense-in-depth in a 1957 report called WASH-740, Possibilities and Consequences of Major Accidents in Large Nuclear Power Plants. “Should some unfortunate sequence of failures lead to destruction of the reactor core … no hazard to the safety of the public would occur unless two additional lines of defense were also breached,” the report said.

These words are at the heart of defense-in-depth as it has been practiced for six decades: multiple layers of defense to protect against accidents and their effects to ensure the risk to the public is acceptably low.

In a recent report issued this spring, Historical Review and Observations of Defense-in-Depth (NUREG/KM-0009), the NRC looks at how the concept has evolved in practice over the years. It also includes views from other government agencies and the international community.

As the report explains, defense-in-depth recognizes that our knowledge is imperfect. Although we plan for all conceivable accidents, the unexpected may still occur. Even if we have anticipated an event, its characteristics and impacts may be unpredictable. Our design and operation of nuclear plants need to be robust enough to compensate for this lack of knowledge. Defense-in-depth offers multiple layers of protection in case one or more layers fail.

So we don’t just rely on preventing an accident; we also need strong defenses to mitigate the effects of any accident that does occur. This applies to nuclear power plants, waste management and security as well.

In practice, defense-in-depth addresses three principles that should be factored into the design and operation of systems and components to provide additional confidence that an accident would not compromise the defensive layers:

  • Redundancy means more than one component performs the same function – for example, having multiple pumps instead of a single one;
  • Independence means these multiple components rely on separate and distinct attributes to function – the multiple pumps have separate piping from the water tank to where they discharge, and are housed in separate compartments; and
  • Diversity means the multiple components performing the same function rely on different design features to operate – motor-driven pumps versus steam-powered pumps.

dindgraphicIn reactor safety, the layers of defense might be:

  • Maintain reactor stability by limiting the ability of events to disrupt operation (with protective measures such as fire-safe or flood-tight doors, seismically designed buildings)
  • Protect the reactor should operation be disrupted (emergency reactor core cooling with redundant pumps)
  • Barrier integrity to guard against a release of radioactivity to the environment (leak-tight containment structures, filtered vents, containment sprays) and
  • Protect the public if a release does occur (emergency preparedness plans)

This versatile framework can apply whether the risk to the public comes from the reactor, spent fuel pool, nuclear waste or security threats.

NRC Finishes Review of Vermont Yankee Decommissioning Planning Report

Neil Sheehan
Public Affairs Officer
Region I

More of a marathon than a sprint, the decommissioning of a nuclear power plant can in some cases take decades. But central to the successful completion of that process is careful planning and vigilant oversight.

vyIn December of 2014, the Vermont Yankee nuclear power plant embarked on that phase of its life after being permanently shut down. As required by the NRC, Entergy, the plant’s owner, submitted a Post-Shutdown Decommissioning Activities Report, or PSDAR, on Dec. 19, 2014.

What exactly is a PSDAR? It is a report designed to provide the NRC and public with a general overview of the company’s proposed decommissioning activities. The report includes estimated costs for decommissioning and an affirmation that the decommissioning can be completed consistent with the site’s environmental statement.

Since the PSDAR only provides information and is not a federal action, it does not require NRC approval. However, the agency does review such submittals to confirm they meet regulatory requirements.

Besides performing an evaluation of the nuts-and-bolts aspects of the decommissioning plans, the NRC staff also reviewed public comments regarding the report. Along those lines, the agency held a public meeting on Feb. 19, 2015, in Brattleboro, Vt., for the purpose of receiving comments. Those remarks and others submitted separately in writing were all considered as the report was being prepared.

The NRC staff has now completed its review of the report and has determined the planned decommissioning activities, schedules and other information described in it are consistent with the agency’s requirements in this area. A copy of the NRC’s letter to Entergy regarding the PSDAR review results will be made available in the agency’s electronic documents system, ADAMS.

Also on the topic of Vermont Yankee’s decommissioning, as of Feb. 1, 2016, the responsibility for Vermont Yankee has been transferred within the NRC from the office responsible for operating reactors to the office responsible for decommissioning nuclear power plants.

Going forward, the Office of Nuclear Material Safety and Safeguards’ Division of Decommissioning, Uranium Recovery and Waste Programs will oversee licensing activities involving Vermont Yankee.

The NRC will continue to perform inspections at Vermont Yankee, with the intention of being on-site anytime a major activity is taking place.

 

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