Tag: nuclear industry

Guiding Our Reviews of Subsequent License Renewal

Albert Wong
Division of License Renewal
Office of Nuclear Reactor Regulation

The NRC has recently published two draft documents intended to guide the staff’s review of “subsequent license renewal” applications – renewals that would allow commercial nuclear power plants to operate beyond 60 years. We’ll use public comments we receive on these to develop final guidance as we prepare to receive the first “SLR” application sometime in 2019.

NUREG-2192As we discussed in an earlier blog post, the NRC licenses plants to operate for 40 years, and the licenses can be renewed for up to 20 years at a time. To date, the agency has renewed the licenses of 81 reactors (two of which have since permanently shut down).

As industry looks to operate some plants beyond 60 years, we’re getting ready to assess the particular challenges to keeping the plants safe. That’s where these draft guidance documents come in.

The documents address material aging and degradation a plant’s structures, systems and components may experience when operating more than 60 years. They also detail aging management programs acceptable to the NRC for licensees to use during the subsequent license renewal period. They incorporate lessons learned and knowledge gained by the staff from recent plant operating experience and previous license renewal reviews.

Long-term operation research sponsored by the NRC, the Electric Power Research Institute, the Department of Energy’s national laboratories and international organizations also informs the guidance.

Public comments on the draft guidance documents will be accepted through February 29. The staff will hold public meetings at NRC headquarters in Rockville, Md., on January 21, January 22 and February 23 to present the reports and receive comments. The final documents should be published by mid-2017.

The draft reports are available on the NRC’s License Renewal Guidance webpage.

NOTE: Comments posted here will NOT be considered public comments on the draft guidance documents. To have your comments considered by the staff as it develops the final guidance documents, please use the federal government’s rulemaking website www.regulations.gov, using Docket ID NRC-2015-0251. Comments may also be mailed to Cindy Bladey, Office of Administration, Mail Stop:  OWFN-12-H08, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001. Comments are accepted through February 29, 2016.

Addressing the Unpredictable Through Mitigation Strategies

Lauren Gibson
Project Manager
Japan Lessons-Learned Directorate
 

The Fukushima accident reminded us how important prior planning is when it comes to safely handling extreme events at a nuclear reactor. We continue to conclude U.S. plants can survive many scenarios, such as loss of offsite power or flooding. After Fukushima, however, we’re requiring plants to have strategies for dealing with the long-term loss of normal safety systems.  Instead of figuring out which events might happen, we’re focusing on significantly improving the plants’ flexibility and diversity in responding to extreme natural phenomena (such as severe flooding, earthquakes, extreme temperatures, etc.).

mitigation_strategies_infographic_r4The plants’ strategies must protect or restore key safety functions indefinitely in the case of an accident. The strategies focus on keeping the core cool, preserving the containment’s barrier that prevents or controls radiation releases, and cooling the spent fuel pool. Plants with more than one reactor must be able to do this for every reactor on site at the same time.

Ideally, plants would have everything for their strategies on site. The strategies must protect the plant indefinitely, however, so plants may need to bring in additional equipment or resources.  The order reflects this by having three phases with different requirements.

The first phase begins with the accident or event.  At this point, the plants will use installed equipment, such as steam-driven pumps or battery-powered systems, to protect or restore safety functions. The plants must be able to shift to the second phase before the installed equipment is exhausted.

The strategies’ second phase uses portable equipment that’s stored onsite, such as additional pumps or generators. This equipment is stored near the reactors and reasonably protected from severe weather or earthquakes. The phase two resources are brought to the reactors and connected to maintain the safety functions. During this phase, plants would also be able to transfer fuel from onsite tanks to the places were it’s needed to run generators and other equipment. Plants have to ensure the third phase can take over before the portable equipment runs out of supplies.

The final phase starts when outside help arrives. The nuclear energy industry is setting up two response centers to provide additional equipment and other resources to any U.S. reactor within 24 hours. One center is in Memphis, Tenn., and the other is in Phoenix, Ariz.

The plants have all submitted a plan for what they intend to do and use in each of these phases. The plans must also explain how the plants will have everything in place by the end of 2016.  We’ve been reviewing those plans and we’re at the point of issuing interim staff evaluations, which let the licensee know whether we think they are on the right track. The NRC will inspect the plants throughout this process to ensure the strategies will get the job done. Our website’s Japan Lessons Learned section has more information about the mitigation strategy requirements and related guidance.

Note: The graphic is now available on our Flickr site.

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