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Peach Bottom Atomic Power Station, Unit 3 - Request for Additional Information Regarding License Amendment Request for Safety Limit Minimum Critical Power Ratio Change (TAC No. ME6931)
 

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HARRISBURG, Pa. (AP) - Pennsylvania's Susquehanna nuclear
power plant faces tougher scrutiny from federal regulators following
 a national review of plant safety.

The Nuclear Regulatory Commission said Tuesday all of the nation's
 104 plants are operating safely, but that problems at Unit 1 of the
Susquehanna plant in Luzerne County made it 1 of 5 with the worst
recent safety performance. No serious problems were detected at
Pennsylvania's four other nuclear plants in the latest assessment.

The low grades reflect four unplanned shutdowns at Susquehanna
Unit 1 between April 2010 and January 2011, including one
necessitated by a faulty gasket that caused 1 million gallons of
river water to leak into the turbine building.

NRC spokesman Neil Sheehan says the agency will conduct at least
one special inspection of the plant later this year.
 

Susquehanna Steam Electric Station Units 1 and 2 - Mid-Cycle Letter for Susquehanna Steam Electric Station Units 1 and 2 (Report 05000387/2011006 and 05000388/2011006)
 
ADAMS Accession No. ML112430469

Three Mile Island Nuclear Station, Unit 1 - Mid-Cycle Letter for Three Mile Island Nuclear Station, Unit 1 (Report 05000289/2011006)

ADAMS Accession No. ML112420674

Peach Bottom Atomic Power Station - Mid-Cycle Letter for Peach Bottom Atomic Power Station (05000277/2011006 AND 05000278/2011006)

ADAMS Accession No. ML112411345

From the U.S. Nuclear Regulatory Commission:

This year has seen a dramatic increase in a question people regularly ask the Nuclear Regulatory Commission: “What magnitude earthquakes are U.S. nuclear power plants designed to withstand?” The answer, however, does not include a specific “magnitude.”

The NRC requires U.S. reactors to withstand a predicted level of ground motion, or acceleration, specific to a given site. Ground acceleration is measured in relation to “g,” the acceleration caused by Earth’s gravity.

An earthquake’s magnitude, often described on the Richter scale, is an expression of how much energy the quake released. It’s not possible to transform a given magnitude alone to ground acceleration at a site. Several important factors affect the relationship between an earthquake’s magnitude and associated ground acceleration, including the distance from the earthquake, the depth of the quake and the site’s local geology (i.e., hard rock or soil). A small earthquake close to a site could therefore generate the same peak ground acceleration as a large earthquake farther away.

The NRC’s requirements call for a nuclear power plant’s design to account for ground acceleration that is appropriate for its location, given the possible earthquake sources that may affect the site and the makeup of nearby faults, etc. Existing U.S. plants were designed on a “deterministic” or “scenario earthquake” basis. In other words, examination of an area’s seismological history provides an understanding of the largest earthquake and associated ground acceleration expected at a plant site.

Later this year, the agency expects to provide existing plants a seismic analysis tool based on work related to applications for new plants, along with the latest information on earthquake sources, so that the plants can perform an updated review. Applications for new nuclear power plants have taken a “probabilistic” approach to determining seismic hazards, looking at a wide range of possible quakes from sources that could affect a given site. The NRC has spent several years examining how these newer techniques can be used to re-evaluate existing nuclear power plant sites.

From NRC News:

The Nuclear Regulatory Commission will present information during the National Academy of Sciences’ (NAS) fifth committee meeting on the NRC-sponsored study, “Analysis of Cancer Risks in Populations Near Nuclear Facilities: Phase 1.” The meeting’s public session will run from 1:20 p.m. – 5 p.m. on Monday, Aug. 29, at the Pew Charitable Trusts Conference Center, 901 E St., NW in Washington, D.C.

The NRC will outline potential next steps for the study and describe the agency’s public outreach and communications efforts. NRC staff will also be available to answer committee member questions. The Environmental Protection Agency will also present information to the committee. The public is welcome to attend and will have the opportunity to comment prior to the end of the meeting. The NAS asks members of the public to register for the meeting, and the NAS website has additional details, although they are subject to change. General questions on the study can be sent via e-mail to: crs@nas.edu.

The NAS project will update the 1990 U.S. National Institutes of Health – National Cancer Institute (NCI) report, “Cancer in Populations Living Near Nuclear Facilities.” The NRC uses the 1990 NCI report as a primary resource when communicating with the public about cancer mortality risk in counties that contain or are adjacent to nuclear power facilities. In the new study, the NRC is asking the NAS to evaluate cancer diagnosis rates, in addition to mortality risk, for populations living near decommissioned, operating and proposed NRC-licensed nuclear facilities. Phase 1 of the NAS study will determine whether a technically defensible approach to meet the goals of the study request is feasible – and if so, the approach will be developed using scientifically sound processes for evaluating cancer risk that could be associated with nuclear facilities.

Exelon Nuclear

FOR IMMEDIATE RELEASE

KENNETT SQUARE, PA. (August 23, 2011) - None of Exelon Nuclear's four Mid-Atlantic nuclear energy stations was affected by this afternoon’s seismic activity in Virginia, and all continue to operate safely at this time. An “Unusual Event” was declared at each of the stations following the seismic activity, in accordance with plant procedures: Peach Bottom Atomic Power Station, Three Mile Island Generating Station and Limerick Generating Station in Pennsylvania, and Oyster Creek Generating Station in New Jersey.