[Federal Register Volume 82, Number 117 (Tuesday, June 20, 2017)]
[Proposed Rules]
[Pages 28017-28020]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-12792]
=======================================================================
-----------------------------------------------------------------------
NUCLEAR REGULATORY COMMISSION
10 CFR Part 50
[NRC-2008-0602, NRC-2002-0020]
RIN 3150-AH43
Decoupling an Assumed Loss of Offsite Power From a Loss-of-
Coolant Accident
AGENCY: Nuclear Regulatory Commission.
ACTION: Discontinuation of rulemaking activity and denial of petition
for rulemaking.
-----------------------------------------------------------------------
SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is discontinuing
the rulemaking activity, ``Decoupling an Assumed Loss of Offsite Power
from a Loss-of-Coolant Accident'' (the LOOP/LOCA rulemaking), and
denying the associated petition for rulemaking (PRM), PRM-50-77. The
purpose of this action is to inform members of the public of the
discontinuation of the rulemaking activity and the denial of the PRM,
and to provide a brief discussion of the NRC's decision regarding the
rulemaking activity and PRM. The rulemaking activity will no longer be
reported in the NRC's portion of the Unified Agenda of Regulatory and
Deregulatory Actions (the Unified Agenda).
DATES: Effective June 20, 2017, the rulemaking activity discussed in
this document is discontinued and PRM-50-77 is denied.
ADDRESSES: Please refer to Docket IDs NRC-2008-0602 (rulemaking
activity) and NRC-2002-0020 (PRM) when contacting the NRC about the
availability of information regarding this document. You may obtain
publicly-available information related to this document using any of
the following methods:
Federal Rulemaking Web site: Go to http://www.regulations.gov and search for Docket IDs NRC-2008-0602 (rulemaking
activity) and NRC-2002-0020 (PRM). Address questions about NRC dockets
to Carol Gallagher; telephone: 301-415-3463; email:
[email protected]. For technical questions, contact the
individual listed in the FOR FURTHER INFORMATION CONTACT section of
this document.
NRC's Agencywide Documents Access and Management System
(ADAMS): You may obtain publicly-available documents online in the
ADAMS Public Documents collection 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
ADAMS accession number for each document referenced in this document
(if that document is available in ADAMS) is provided the first time
that a document is referenced.
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, Maryland 20852.
FOR FURTHER INFORMATION CONTACT: Robert Beall, Office of Nuclear
Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC
20555-0001; telephone: 301-415-3874; email: [email protected].
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Background
[[Page 28018]]
II. Process for Discontinuing Rulemaking Activities
III. Decoupling an Assumed Loss of Offsite Power From a Loss-of-
Coolant Accident
IV. Petition for Rulemaking (PRM-50-77)
V. Conclusion
I. Background
In both SECY-01-0133, ``Status Report on Study of Risk-Informed
Changes to the Technical Requirements of 10 CFR part 50 (Option 3) and
Recommendations on Risk-Informed Changes to 10 CFR 50.46 (ECCS
Acceptance Criteria),'' dated July 23, 2001 (ADAMS Accession No.
ML011800492), and SECY-02-0057, ``Update to SECY-01-0133, 'Fourth
Status Report on Study of Risk-Informed Changes to the Technical
Requirements of 10 CFR part 50 (Option 3) and Recommendations on Risk-
Informed Changes to 10 CFR 50.46 (ECCS Acceptance Criteria)' '' (ADAMS
Accession No. ML020660607), the NRC staff recommended developing a
possible risk-informed alternative to reliability requirements in Sec.
50.46 of title 10 of the Code of Federal Regulations (10 CFR) and
General Design Criterion (GDC) 35, ``Emergency Core Cooling,'' of
appendix A, ``General Design Criteria for Nuclear Power Plants,'' to 10
CFR part 50, ``Domestic Licensing of Production and Utilization
Facilities.'' On March 31, 2003, in the staff requirements memorandum
(SRM) for SECY-02-0057, the Commission directed the NRC staff to
proceed with a rulemaking to risk-inform the emergency core cooling
system (ECCS) functional reliability requirements in GDC 35 (ADAMS
Accession No. ML030910476). This proposed rulemaking would provide
licensees an option to relax the current analysis requirements for
considering a loss of offsite power (LOOP) to occur coincident with a
large-break loss-of-coolant accident (LOCA) (the LOOP/LOCA rulemaking).
The SRM also stated that the NRC staff should include relevant issues
and uncertainties that can impact plant risk (e.g., delayed LOOP and
``double sequencing'' \1\ of safety functions).
---------------------------------------------------------------------------
\1\ Double sequencing is defined as a situation where
electrically powered safety and accident mitigation equipment
automatically start, shut down, and restart in rapid succession when
called on to operate. Delayed LOOP and double sequencing were
evaluated and dispositioned in GSI-171, ``ESF Failure from LOOP
Subsequent to LOCA,'' for the current regulations (https://www.nrc.gov/sr0933/Section%203.%20New%20Generic%20Issues/171r1.html#). GSI-171 does not need to be reevaluated if the LOOP/
LOCA rulemaking is discontinued.
---------------------------------------------------------------------------
In parallel with the LOOP/LOCA rulemaking, the NRC pursued a
separate rulemaking for a risk-informed definition of large-break LOCA
ECCS analysis requirements (the 50.46a ECCS rulemaking). The proposed
regulations in the 50.46a ECCS rulemaking would have allowed both
pressurized water reactors (PWRs) and boiling water reactors (BWRs) to
decouple a LOOP from a LOCA for certain break sizes.
II. Process for Discontinuing Rulemaking Activities
When the NRC staff identifies a rulemaking activity that can be
discontinued, the staff requests approval from the Commission to
discontinue it in a Commission paper. The Commission provides its
decision in an SRM. If the Commission approves discontinuing a
rulemaking activity, the NRC staff informs the public of the
Commission's decision.
A rulemaking activity may be discontinued at any stage in the
rulemaking process. For a rulemaking activity that has received public
comments, the NRC considers those comments before discontinuing the
rulemaking activity; however, the NRC staff will not provide individual
comment responses.
After Commission approval to discontinue the rulemaking activity,
the NRC staff updates the next edition of the Unified Agenda to
indicate that the rulemaking is discontinued. The rulemaking activity
will appear in the completed section of that edition of the Unified
Agenda but will not appear in future editions.
A rulemaking activity proposed for discontinuation may have been
initiated in response to accepting one or more PRMs, or may include
issues from one or more PRMs that were accepted and added to the
ongoing related rulemaking activity. Therefore, discontinuation of the
rulemaking activity also requires the NRC to take action to resolve the
associated PRM(s) and to inform the petitioner(s) and the public of the
NRC's action. The NRC's action to discontinue a rulemaking would
normally result in NRC denial of the associated PRM for the same
reasons.
III. Decoupling an Assumed Loss of Offsite Power From a Loss-of-Coolant
Accident
The Boiling Water Reactor Owners Group (BWROG) submitted for NRC
review a licensing topical report NEDO-33148, ``Separation of Loss of
Offsite Power from Large Break LOCA,'' dated April 27, 2004 (ADAMS
Accession No. ML041210900). The BWROG stated that the licensing topical
report would support plant-specific exemption requests to implement
plant changes that are currently not possible with the existing
regulatory requirements to consider a LOOP coincident with a large
break LOCA. The NRC intended to derive some of the technical support
for the proposed LOOP/LOCA rulemaking from NEDO-33148. The proposed
rulemaking would allow BWR licensees to make specific design changes
that otherwise could not be made without exemptions from the current 10
CFR 50.46 requirements.
The BWROG initially chose to pursue an approach that relied on a
generic probabilistic risk assessment (PRA) and other published reports
for justification of several important assumptions made in NEDO-33148
(e.g., large-break LOCA probability, consequential/delayed LOOP, and
double sequencing of electrical loads). The BWROG proposed to address
these issues in Revision 2 of NEDO-33148, which was submitted on August
25, 2006 (ADAMS Accession No. ML062480321). Revision 2 presented the
risk analyses as risk assessment methodologies rather than a generic
risk assessment. In a letter to the BWROG dated March 24, 2008 (ADAMS
Accession No. ML080230696), the NRC detailed the conditions and
limitations that were required for approval of NEDO-33148, Revision 2.
Some of the outstanding technical issues included LOOP/LOCA frequency
determinations, seismic contributions to break frequency, the
maintenance of defense-in-depth, and the treatment of delayed LOOP and
double sequencing issues. The NRC staff determined that these issues
needed to be adequately addressed in order to complete a regulatory
basis that could support a proposed LOOP/LOCA rulemaking.
On June 12, 2008, the BWROG formally withdrew its licensing topical
report, NEDO-33148, from further NRC review and discontinued its
supporting effort. The BWROG's withdrawal letter (ADAMS Accession No.
ML081680048) stated that further development of NEDO-33148 ``is no
longer cost effective and, if ultimately approved in the form presently
desired by NRC staff, adoption by licensees would most likely be
prohibitively expensive.'' The withdrawal of NEDO-33148 and the
discontinued effort by the BWROG demonstrated a potential loss of
industry interest in this initiative.
In SECY-09-0140, ``Rulemaking Related to Decoupling an Assumed Loss
of Offsite Power From a Loss-of-Coolant Accident, 10 CFR part 50,
Appendix A, General Design Criterion 35 (RIN 3150-AH43),'' dated
September 28, 2009 (ADAMS Accession No. ML092151078), the NRC staff
proposed three options for the Commission to consider as a path
[[Page 28019]]
forward on the LOOP/LOCA rulemaking: (1) Discontinue the LOOP/LOCA
rulemaking, (2) proceed with the LOOP/LOCA rulemaking without the BWROG
topical report, or (3) continue to defer the LOOP/LOCA rulemaking until
implementation of the 50.46a ECCS rulemaking. The Commission approved
the third option, to defer the LOOP/LOCA rulemaking, in the SRM for
SECY-09-0140, dated July 2, 2010 (ADAMS Accession No. ML101830056).
In SECY-16-0009, ``Recommendations Resulting from the Integrated
Prioritization and Re-Baselining of Agency Activities,'' dated January
31, 2016 (ADAMS Accession No. ML16028A189), the NRC staff recommended
that the 50.46a ECCS rulemaking be discontinued. In the SRM for SECY-
16-0009, dated April 13, 2016 (ADAMS Accession No. ML16104A158), the
Commission approved discontinuing the 50.46a ECCS rulemaking. A Federal
Register notice, published on October 6, 2016 (81 FR 69446), informed
the public of the NRC's decision to discontinue the 50.46a ECCS
rulemaking.
In support of the potential risk-informed alternative to
reliability requirements in 10 CFR 50.46 and GDC 35, the NRC performed
substantial work in a number of technical areas, including estimating
LOCA frequencies and the conditional probability of a LOOP, given a
LOCA (see memorandum from A. Thadani to S. Collins, ``Transmittal of
Technical Work to Support Possible Rulemaking on a Risk-Informed
Alternative to 10 CFR 50.46/GDC 35,'' dated July 31, 2002 (ADAMS
Accession No. ML022120661)). As part of this work, the NRC identified a
number of areas of uncertainty associated with estimating the
conditional probability of a LOOP, given occurrence of a LOCA,
including very limited data on major ECCS actuations and LOOPs after
such actuations, incomplete knowledge about all of the factors that can
impact the probability of consequential LOOP because of electrical
transient factors,\2\ and the impact on offsite system voltage due to
deregulation of the electric utility industry. To complete a fully
developed regulatory basis for the LOOP/LOCA rulemaking, the NRC staff
would need to ensure that these areas of uncertainty are adequately
addressed as part of the rulemaking activity.
---------------------------------------------------------------------------
\2\ As used here, transient factors include the electrical
disturbance triggered by starting electrically powered safety and
accident mitigation equipment as a result of the LOCA and the
conditions of the offsite transmission system grid.
---------------------------------------------------------------------------
On June 28, 2016, and October 26, 2016, the NRC held public
meetings (ADAMS Accession Nos. ML16203A003 and ML16319A153,
respectively) to receive external stakeholder feedback on the need for
a LOOP/LOCA rulemaking. The NRC presented information on what would be
required by the NRC and the industry to continue the proposed
rulemaking activity. The NRC's position was similar to the March 24,
2008, letter to the BWROG detailing the information that would be
needed to complete review of licensing topical report NEDO-33148.
Representatives from the Nuclear Energy Institute and the PWR and BWR
Owners Groups also presented their perspectives on continuing the
proposed LOOP/LOCA rulemaking effort. The industry re-stated its view
from the 2008 withdrawal of the licensing topical report that the
estimated implementation costs would be prohibitively expensive for the
benefit received. In addition, industry representatives recommended
that the NRC staff devote its resources to other risk-informed
licensing activities that have significantly higher industry interest,
such as applications to implement 10 CFR 50.69, ``Risk-informed
categorization and treatment of structures, systems and components for
nuclear power reactors,'' and risk-informed technical specifications.
The NRC is discontinuing the LOOP/LOCA rulemaking activity. The
current regulations provide adequate protection of public health and
safety. This rulemaking would have provided licensees an option to
relax the current analysis requirements for considering a LOOP to occur
coincident with a LOCA. Based on the feedback from the industry, it is
unlikely that any licensee would seek licensing basis changes that
would rely on the proposed rulemaking. The issues that caused the
industry to withdraw the BWROG topical report in 2008 are still
applicable today and the industry has greater interest in the progress
of other risk-informed initiatives. Therefore, pursuit of this effort
would likely have minimal practical impact on safety. Based upon (1)
the assessment that there is no current adequate protection issue with
respect to compliance with the current ECCS rule, (2) the lack of
significant safety benefits from the rulemaking, (3) the industry's
representation that it would be unlikely for any licensee to
voluntarily use the LOOP/LOCA rule because the estimated implementation
costs would be prohibitively expensive for the benefit received, and
(4) the industry's stated interest in pursuing other risk-informed
licensing activities, the NRC is discontinuing the LOOP/LOCA
rulemaking.
IV. Petition for Rulemaking (PRM-50-77)
On May 2, 2002, the NRC received a PRM from Bob Christie,
Performance Technology (ADAMS Accession No. ML082530041), related to
the topics in the proposed LOOP/LOCA rulemaking. The PRM requested that
the NRC amend its regulations in appendix A to 10 CFR part 50 to
eliminate the requirement to assume a LOOP coincident with postulated
accidents. The NRC docketed the petition and assigned it Docket No.
PRM-50-77. The NRC published a notice of receipt and request for
comment on the PRM on June 13, 2002 (67 FR 40622), and received one
comment supporting the PRM from the Strategic Teaming and Resource
Sharing organization (ADAMS Accession No. ML022490192). The petition
was resolved by a decision to consider its issues within the LOOP/LOCA
rulemaking, but the petition remained open because of the ongoing
developments related to this rulemaking. However, in late 2007, the NRC
Executive Director for Operations approved changes to the PRM process
to enhance the efficiency and effectiveness of dispositioning a PRM. As
a result of those enhancements, the NRC closed this petition on April
13, 2009 (74 FR 16802), with a commitment to follow through with the
original resolution to consider it within the LOOP/LOCA rulemaking.
Because of the agency's decision to discontinue the LOOP/LOCA
rulemaking, the associated petition, PRM-50-77, is denied for the
reasons discussed above. As provided at Sec. 2.803(i)(2), the NRC has
decided not to complete the rulemaking action and is documenting this
denial of the PRM in the docket for the closed PRM.
V. Conclusion
The NRC is no longer pursuing the LOOP/LOCA rulemaking and is
denying PRM-50-77 for the reasons discussed in this document. In the
next edition of the Unified Agenda, the NRC will update the entry for
the rulemaking activity and reference this document to indicate that
the rulemaking is no longer being pursued. The rulemaking activity will
appear in the completed actions section of that edition of the Unified
Agenda but will not appear in future editions. If the NRC decides to
pursue a similar or related rulemaking activity in the future, it will
inform the public through a new rulemaking entry in the Unified Agenda.
Dated at Rockville, Maryland, this 14th day of June 2017.
[[Page 28020]]
For the Nuclear Regulatory Commission.
Annette L. Vietti-Cook,
Secretary of the Commission.
[FR Doc. 2017-12792 Filed 6-19-17; 8:45 am]
BILLING CODE 7590-01-P