[Federal Register Volume 78, Number 38 (Tuesday, February 26, 2013)]
[Pages 13097-13099]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-04396]




Electric Power Research Institute; Seismic Evaluation Guidance

AGENCY: U.S. Nuclear Regulatory Commission.

ACTION: Endorsement letter; issuance.


SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is issuing an 
endorsement letter with clarifications of Electric Power Research 
Institute (EPRI)-1025287, ``Seismic Evaluation Guidance: Screening, 
Prioritization and Implementation Details (SPID) for the Resolution of 
Fukushima Near-Term Task Force Recommendation 2.1: Seismic,'' Revision 
0, hereafter referred to as the SPID report. This SPID report provides 
guidance and clarification of an acceptable approach to assist nuclear 
power reactor licensees when responding to the NRC staff's request for 
information dated March 12, 2012, Enclosure 1, ``Recommendation 2.1: 
Seismic.'' The NRC staff's endorsement

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letter includes additional clarifications on the: (1) Use of the 
Individual Plant Examination of External Events (IPEEE) submittals for 
screening purposes; (2) development of foundation input response 
spectra (FIRS) consistent with the site response used in the 
development of the site-specific ground motion response spectrum 
(GMRS); (3) updating the seismic source models; and (4) development of 
the site response.

ADDRESSES: You may access information related to this document, which 
the NRC possesses and is publicly available, by searching on http://www.regulations.gov under Docket ID NRC-2013-0038.
     Federal Rulemaking Web site: Go to http://www.regulations.gov and search for Docket ID NRC-2013-0038. Address 
questions about NRC dockets to Carol Gallagher; telephone: 301-492-
3668; email: [email protected].
     NRC's Agencywide Documents Access and Management System 
(ADAMS): You may access publicly-available documents online in the NRC 
Library at http://www.nrc.gov/reading-rm/adams.html. To begin the 
search, select ``ADAMS Public Documents'' and then select ``Begin Web-
based ADAMS Search.'' For problems with ADAMS, please contact the NRC's 
Public Document Room (PDR) reference staff at 1-800-397-4209, 301-415-
4737, or by email to [email protected]. The NRC staff's endorsement 
letter is available under ADAMS Accession No. ML12319A074. The NRC 
staff's request for information dated March 12, 2012, Enclosure 1, 
``Recommendation 2.1: Seismic'' is available under ADAMS Accession No. 
     NRC's PDR: You may examine and purchase copies of public 
documents at the NRC's PDR, Room O1-F21, One White Flint North, 11555 
Rockville Pike, Rockville, MD 20852.

FOR FURTHER INFORMATION CONTACT: Mrs. Lisa M. Regner, Japan Lessons-
Learned Project Directorate, Office of Nuclear Reactor Regulation, U.S. 
Nuclear Regulatory Commission, Washington, DC 20555-0001; telephone: 
301-415-1906; email: [email protected].


Background Information

    The endorsement letter for the SPID report is being issued to the 
public to describe guidance that is acceptable for responding to the 
request to reevaluate seismic hazards at operating reactor sites, as 
discussed in Enclosure 1 ``Recommendation 2.1: Seismic,'' of the NRC 
staff's request for information (RFI), ``Request for Information 
Pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Part 
50.54(f) Regarding Recommendations 2.1, 2.3, and 9.3, of the Near-Term 
Task Force Review of Insights from the Fukushima Dai-ichi Accident,'' 
dated March 12, 2012.
    The NRC issued the RFI following the NRC staff's evaluation of the 
earthquake and tsunami, and resulting nuclear accident, at the 
Fukushima Dai-ichi nuclear power plant in March 2011. Enclosure 1 to 
the RFI requests licensees and holders of construction permits under 10 
CFR Part 50, to reevaluate the seismic hazards at their sites using 
present-day NRC requirements and guidance, and identify actions taken 
or planned to address plant-specific vulnerabilities associated with 
the updated seismic hazards. Based on this information, the NRC staff 
will determine whether additional regulatory actions are necessary to 
protect against the updated hazards. The principal purpose of the SPID 
report is to provide guidance for responding to the RFI by describing 
strategies for screening, prioritization, and potential interim 
actions, as well as implementation guidance for the risk evaluation 
that are acceptable to the NRC staff.

Basis for Endorsement

    The NRC staff interacted with the stakeholders on development of 
the SPID report with a focus on screening, prioritization, and 
implementation details as they relate to performing a seismic 
reevaluation. The SPID report is the product of significant interaction 
between the NRC, Nuclear Energy Institute, EPRI, and other stakeholders 
at over fifteen public meetings \1\ over a 9-month period. These 
interactions and the insights gained from the meetings allowed for the 
development of this document in a very short time frame. The meetings 
helped develop the expectations for how licensees would perform plant 
evaluations after having updated their seismic hazard information. At 
each meeting, the NRC staff provided its comments on the current 
version of the SPID report and discussed with stakeholders subsequent 
proposed revisions to the document. This iterative process, over 
several months, resulted in the final version of the document. The NRC 
staff's endorsement of the SPID report, subject to the additional 
guidance noted below, is based on this cumulative development process 
resulting from the extensive interactions between stakeholders and the 
NRC staff.

    \1\ Public meetings were held on March 1-2, April 2-3, May 15-
16, June 14, July 24-25, August 16 and 30, September 11 and 21, 
October 9 and 18, November 5, 9, 14, 20, and 26, 2012.

    The NRC staff has reviewed the SPID report and confirmed that it 
would provide licensees with the guidance necessary to perform seismic 
reevaluations and report the results to the NRC in a manner that will 
address the Requested Information items (1) through (9) in Enclosure 1 
of the 50.54(f) letter. The SPID report is intended to provide 
sufficient guidance for all sites, however, each site is unique and 
requirements for analysis can vary. In cases where the SPID report may 
not account for the unique characteristics of a site, prudent and sound 
engineering judgment should be employed to assure all issues bearing on 
the hazard and risk evaluations are adequately addressed. Instances 
when unique site characteristics require such engineering judgment, or 
require analysis that is not included in the SPID report, should be 
clearly identified, along with the measures taken to assure the unique 
site characteristics are appropriately addressed. Although the NRC 
staff finds that the performance and reporting of the seismic 
reevaluation in accordance with this document would be responsive to 
the 50.54(f) letter, there are four further issues described below for 
which the staff provides additional guidance. These issues are: (1) The 
use of the IPEEE submittals for screening purposes; (2) development of 
FIRS consistent with the site response used in the development of the 
site-specific GMRS; (3) updating the seismic source models; and (4) 
development of the site response.

Use of IPEEE for Screening

    Section 3.3 of the EPRI guidance document provides the criteria 
used to determine if the licensee's previous IPEEE submittal is 
adequate to use for screening purposes. A seismic assessment performed 
as part of the IPEEE program that demonstrates a plant capacity that is 
higher than the new GMRS can be used to screen out plants, provided 
they meet certain adequacy criteria.
    Each licensee has the option of demonstrating the adequacy of its 
previous IPEEE submittal for screening purposes as part of its response 
to the 50.54(f) letter. The NRC staff will review each submittal and 
determine whether the provided information demonstrates the adequacy of 
the IPEEE analysis and risk insights. The licensee's description of 
each of the adequacy criteria, described in Section 3.3 of the SPID 
report, will be reviewed by the NRC staff in its integrated totality, 
rather than using a pass/fail approach. As such,

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even if one or more of the criteria are not deemed to be adequate, the 
NRC staff may still decide that the overall IPEEE analysis is adequate 
to support its use for screening purposes. The NRC staff may conduct 
site visits to view IPEEE documentation referenced in support of the 
IPEEE adequacy submittal.

Development of FIRS

    The SPID report does not discuss the development of FIRS used for 
performing soil-structure interaction analyses. Consistent with 
guidance described in DC/COL-ISG-017, ``Ensuring Hazard-Consistent 
Seismic Input for Site Response and Soil Structure Interaction 
Analyses,'' the FIRS should be derived in a manner consistent with the 
site response used in the development of the site-specific GMRS. As 
such, the FIRS should be derived as performance-based site-specific 
response spectra at the foundation level in the free field. The 
starting point for development of the FIRS should be the same hard rock 
elevation used as the starting point for developing the GMRS. As the 
engineering properties of soil are strain-dependent and can be highly 
non-linear, the characterization of soil layers and their associated 
properties used in the GMRS analysis should also be used for the 
derivation of the site-specific FIRS at the foundation elevation. The 
performance-based FIRS can be developed using either a full-column 
outcrop motion that includes the effect of the soil above, or as a 
geologic outcrop motion for which the soil layers above the foundation 
elevation have been removed.

Updating the Central and Eastern United States (CEUS)-Seismic Source 
Characterization (SSC) Model

    Section 2.2 of the SPID report provides an overview of the CEUS-SSC 
model and explains why it is appropriate to use without update for the 
seismic reevaluations. Specifically, Section 2.2 states ``for site-
specific licensing applications or site-specific safety decisions, 
these seismic sources would be reviewed on a site-specific basis to 
determine if they need to be updated. Such evaluations would be 
appropriate in a licensing application, where focus could be made on 
site-specific applications. However, for a screening-level study of 
multiple plants for the purpose of setting priorities, the use of these 
seismic sources as published is appropriate.''
    The NRC staff agrees that the CEUS-SSC model does not need to be 
updated for the seismic reevaluations, but the staff's rationale is 
different than that presented in the SPID report. Specifically, the 
staff has determined that the CEUS-SSC model does not need to be 
updated because the model is up-to-date and is sufficiently refined to 
allow a site-specific source model to be developed. To adequately 
respond to the 50.54(f) letter, a site-specific GMRS should be 
calculated for each plant so that an informed decision can be made 
regarding which plants will be required to complete a risk evaluation. 
Further, the site-specific GMRS will also be used in the risk 
    Prior to issuing the CEUS-SSC model, the Technical Integration Team 
considered potentially significant events (such as the 2011 Mineral, VA 
earthquake) that had occurred after the model was developed, and 
determined that those events did not change their interpretations of 
seismic sources or earthquake recurrence rates. If a significant 
earthquake in the CEUS were to occur or new information were to emerge 
during the reevaluation period that could require an update of the 
CEUS-SSC model, the staff expects licensees to evaluate the 
significance of the new information to determine if the CEUS-SSC model 
needs to be updated in order to appropriately respond to the 50.54(f) 

Site Response

    Section 2.4.1 and Appendix B of the SPID report provides guidance 
on how to develop the site response in cases where limited site 
response data exists. As stated in Appendix B, the NRC staff expects 
licensees to use available geologic, geotechnical, and geophysical data 
collected during the initial licensing or subsequent activities at the 
site to the extent practicable. Where limited site response data 
exists, information from core borings and data collected from site and 
regional evaluations should be used to develop the site response 
amplification. Section 4 of the SPID report states that licensees 
should provide the basis for the site responses used in the 
reevaluations. The NRC staff expects site-specific geology, 
geotechnical, and geophysical information to be a significant part of 
the basis.


    An NRC staff member did not agree with some content of the SPID 
report and submitted a non-concurrence on the SPID endorsement letter. 
In accordance with the NRC's non-concurrence process, NRC management 
and staff worked to address the staff member's concerns, and 
documentation of the non-concurrence can be found in ADAMS at Accession 
No. ML12324A195.

60-Day Response

    In accordance with the 50.54(f) letter, each licensee is to submit 
to the NRC its intention to follow the NRC-endorsed seismic 
reevaluation guidance, or an alternative approach, 60 days after the 
issuance of the NRC-endorsed guidance. For the purpose of meeting this 
deadline, the 60-day response period commences on the date the 
endorsement letter is published in the Federal Register.

Backfitting and Issue Finality

    This endorsement letter does not constitute backfitting as defined 
in 10 CFR 50.109 (the Backfit Rule) and is not otherwise inconsistent 
with the issue finality provisions in Part 52, ``Licenses, 
Certifications, and Approvals for Nuclear Power Plants,'' of 10 CFR. 
This endorsement letter provides guidance on an acceptable method for 
implementing the March 12, 2012, RFI. Applicants and licensees may 
voluntarily use the guidance in the SPID report, as clarified by the 
NRC staff in the endorsement letter, to comply with the RFI. Methods, 
analyses, or solutions that differ from those described in the SPID 
report may be deemed acceptable if they provide sufficient basis and 
information for the NRC staff to verify that the proposed alternative 
is acceptable.

Congressional Review Act

    This endorsement letter is a rule as designated in the 
Congressional Review Act (5 U.S.C. 801-808). The Office of Management 
and Budget has found that this is a major rule in accordance with the 
Congressional Review Act.

    Dated at Rockville, Maryland, this 15th day of February 2013.

    For the Nuclear Regulatory Commission.
David L. Skeen,
Director, Japan Lessons-Learned Project Directorate, Office of Nuclear 
Reactor Regulation.
[FR Doc. 2013-04396 Filed 2-25-13; 8:45 am]