[Federal Register Volume 81, Number 44 (Monday, March 7, 2016)]
[Proposed Rules]
[Pages 11681-11686]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-05028]
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NUCLEAR REGULATORY COMMISSION
10 CFR Parts 50, 52, 54, and 100
[Docket Nos. PRM-50-106; NRC-2012-0177]
Environmental Qualification of Electrical Equipment
AGENCY: Nuclear Regulatory Commission.
ACTION: Petition for rulemaking; denial.
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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is denying a
petition for rulemaking (PRM) submitted by the Natural Resources
Defense Council, Inc. (NRDC), and Mr. Paul M. Blanch (collectively, the
petitioners) on June 18, 2012. The petitioners requested that the NRC
amend its regulations to clearly and unequivocally require the
environmental qualification of all safety-related cables, wires,
splices, connections and other ancillary electrical equipment that may
be subjected to submergence and/or moisture intrusion during normal
operating conditions, severe weather, seasonal flooding, and seismic
events, and post-accident conditions, both inside and outside of a
reactor's containment building. The NRC is denying this petition
because the current regulations already address environmental
qualification in both mild and design basis event conditions of
electrical equipment located both inside and outside of the containment
building that is important to safety, and the petition does not provide
significant new or previously unconsidered information sufficient to
justify rulemaking.
DATES: The docket for the petition for rulemaking, PRM-50-106, is
closed on March 7, 2016.
[[Page 11682]]
ADDRESSES: Please refer to Docket ID NRC-2012-0177 when contacting the
NRC about the availability of information regarding this petition. You
may obtain publicly-available information related to the petition by
using any of the following methods:
Federal Rulemaking Web site: Go to http://www.regulations.gov and search for Docket ID NRC-2012-0177. 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 (if it is available
in ADAMS) is provided the first time that it is mentioned in the
SUPPLEMENTARY INFORMATION section.
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: Margaret Ellenson, Office of Nuclear
Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC
20555-0001, telephone: 301-415-0894; email: [email protected].
SUPPLEMENTARY INFORMATION:
Table of Contents
I. The Petition
II. NRC Analysis
III. Determination of Petition
I. The Petition
On June 18, 2012, the NRC received a petition for rulemaking filed
jointly by the NRDC and Mr. Paul Blanch (ADAMS Accession No.
ML12177A377). The petitioners requested that the NRC amend its
regulations in parts 50, 52, 54, and 100 of title 10 of the Code of
Federal Regulations (10 CFR) to clearly and unequivocally require the
environmental qualification of all safety-related cables, wires,
splices, connections and other ancillary electrical equipment that may
be subjected to submergence and/or moisture intrusion during normal
operating conditions, severe weather, seasonal flooding, and seismic
events, and post-accident conditions, both inside and outside of a
reactor's containment building.
The petition was docketed by the NRC on June 22, 2012, and was
assigned Docket No. PRM-50-106. On September 27, 2012 (77 FR 59345),
the NRC published a notice of receipt in the Federal Register. The NRC
did not request public comment on PRM-50-106.
II. NRC Analysis
The petitioners raised three issues in support of their request
that the NRC amend the regulations related to environmental
qualification of electrical equipment at nuclear power plants. The
three issues and the NRC's responses to each issue are presented in
this section.
Issue 1: Through the issuance of Generic Letter (GL) 82-09,
``Environmental Qualification of Safety-Related Electrical Equipment,''
dated April 20, 1982 (ADAMS Accession No. ML031080281), the NRC staff
limited the scope of Sec. 50.49 based on the location of the
electrical equipment.
The petitioners stated that as a result of the accident at Three
Mile Island, the NRC strengthened the regulatory requirements for
electrical equipment by, among other things, revising Sec. 50.49(e) to
add paragraph (6) to address the possibility of electrical equipment
submergence. The petitioners asserted that Sec. 50.49(e)(6), as
written, did not limit or restrict its applicability based upon the
location of the equipment, but that the NRC staff limited this
applicability through a question and answer (Q&A) set in GL 82-09:
Q. For equipment qualification purposes, what are the staff
requirements concerning submergence of equipment outside containment?
A. The staff requires that the licensee submit documentation on the
qualification of safety-related equipment that could be submerged due
to a high energy line break outside containment.
The petitioners asserted that the problem with this excerpt from GL
82-09 is that safety-related cables and wires outside containment are
routinely submerged in water not only during high energy line breaks
(HELBs), but also during a reactor's normal operation. The petitioners
argued that the 1979 Three Mile Island accident and laboratory testing
have shown that moisture intrusion and submergence of electrical cables
and wires significantly increase the probability of failure, which also
causes the failure of connected components such as emergency core
cooling system motors and pumps, valves, controls, and instrumentation.
The petitioners asserted that the safety implications from the failure
of a safety-related cable inside containment submerged by an accident,
outside containment submerged by a high energy line break, or outside
containment submerged by nature, are identical--the safety function is
lost.
NRC Response to Issue 1: The regulations at Sec. 50.49,
``Environmental qualification of electric equipment important to safety
for nuclear power plants,'' are applicable to electrical equipment
located outside containment as well as inside. The January 21, 1983,
Federal Register notice of the final Sec. 50.49 rule (48 FR 2730) made
this clear by noting that nuclear power plant equipment important to
safety must be able to perform its safety functions throughout its
installed life, and that this requirement applies to equipment inside
as well as outside containment. (See 48 FR 2731.) The Q&A referenced by
the petitioners is itself premised on the applicability of Sec. 50.49
to important to safety electrical equipment outside of containment.
Regardless of its location inside or outside containment, if any
important to safety electrical equipment is near enough to a high
energy line (e.g., steam line, feedwater, blow-down, charging, or
letdown lines) that the equipment's performance could be adversely
affected by a rupture of that line, Sec. 50.49 requires that the
equipment be qualified to withstand any environmental conditions that
may result from such an event. Section 50.49 was established to impose
additional requirements beyond those established by Sec. 50.65,
``Requirements for monitoring the effectiveness of maintenance at
nuclear power plants;'' 10 CFR part 50, appendix A, ``General Design
Criteria [GDC] For Nuclear Power Plants;'' \1\ and 10 CFR part 50,
appendix B, ``Quality Assurance Criteria for Nuclear Power Plants and
Fuel Processing Plants.'' The additional requirements in Sec. 50.49
apply to important to safety electrical equipment that could be subject
to postulated design basis events (DBEs) that could affect: (1) The
integrity of the reactor coolant pressure boundary; (2) the capability
to shut the reactor down safely and keep it safe; or (3) the capability
to prevent or mitigate accidents that could result in potential
[[Page 11683]]
offsite exposures comparable to NRC emergency planning guidelines. As
the cited GL 82-09 Q&A indicates, a HELB was the most probable such DBE
involving submergence outside of containment for which the NRC staff
believed that a power reactor's important to safety electrical
equipment must be environmentally qualified.
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\1\ The GDC pertains to water cooled nuclear plants and
establishes the minimum requirements for their principal design
criteria (36 FR 3256; February 20, 1971, as amended).
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The NRC agrees with the petitioners that safety-related cables and
other electrical equipment must be fully able to function, not only
within an operating environment affected by a HELB under Sec. 50.49,
but also over the entire length of its system, even those portions not
exposed to a HELB. Criterion 18 of 10 CFR part 50, appendix A, requires
that electric power systems important to safety be designed so that
important areas and features permit appropriate periodic inspection and
testing. Example areas and features specified are the following:
wiring, insulation, connections, and switchboards. Criterion 18 also
requires the systems to be designed with a capability to test
periodically the operability and functional performance of the
components of the systems and the operability of the system as a whole.
As the petitioners rightly point out, designing the entirety of an
electrical safety system for inspectability and testability is
essential because ``[i]t matters little if the portion of a safety-
related cable inside [or] outside containment in a high energy line
break area survive[s] if another portion of that same cable routed
underground fails due to submergence.'' It is also important to note
that the NRC's design and qualification requirements for underground or
inaccessible wires, cables, and ancillary equipment are inspected and
enforced. The NRC's inspection procedures direct that inspections of
electrical equipment at risk of flooding or exposure to moisture be
conducted annually.
The NRC disagrees with the petitioners' assertion that GL 82-09 has
restricted the applicability of Sec. 50.49 regulatory requirements for
safety-related equipment according to its location. Generic letters do
not have the legal authority of a final rule promulgated after due
public notice and comment, as was Sec. 50.49. The Q&A in GL 82-09 does
not exempt any safety-related equipment that could be submerged, inside
or outside containment, from the environmental qualifications (EQ)
requirements of Sec. 50.49. The purpose of the GL 82-09 Q&A cited by
the petitioners was simply to clarify that under Sec. 50.49, licensees
must submit information on the EQ of important to safety equipment that
could be submerged due to a high energy line break outside containment.
The applicability of Sec. 50.49 is not limited to a HELB, although
after more than 30 years of operating experience and risk analysis, a
HELB remains the most probable DBE involving submergence outside
containment that meets the Sec. 50.49 criteria for the subset of DBEs
that could result in a severe accident. The clarifying Q&A was
important because the GL was providing information in the event of a
HELB, not describing the entire universe of postulated DBEs to which
Sec. 50.49 could apply.
Issue 2: Safety-related cable subject to submergence, condensation,
or moisture located in a ``mild environment'' should not be exempted
from the environmental qualification requirements of Sec. 50.49.
The petitioners argued that rulemaking is necessary to ensure that
electrical cables and wires will be properly qualified for
environmental conditions they may experience during normal operation
(i.e., a mild environment) as well as in an accident. The petitioners
claimed the need for rulemaking and clarification of Sec. 50.49 to
address cables that may be exposed to non-mild environments during
normal, abnormal, and accident conditions. The petitioners noted that
electrical cables and wires ``are prone to accelerated failure rates
when submerged in water or exposed to high humidity unless designed and
qualified for these environmental conditions.'' The petitioners stated
that the NRC prioritized the inspection of cable penetrations after the
1979 Three Mile Island accident based on the probability of their
impairment, mostly due to submergence and moisture. The petitioners
argued that ``[i]f these conditions cause a high probability of
impairment following an accident, then it is logical to assume that
these conditions produce a similar outcome in the absence of or prior
to an accident as well.'' In support of their case for a rulemaking to
address this impairment, the petitioners also referenced a 1996 study
by the U.S. Department of Energy (DOE) (ADAMS Accession No.
ML031140264) and three studies by the Electric Power Research Institute
(EPRI), ``Plant Support Engineering: Life Cycle Management Planning
Sourcebooks: Medium-Voltage (MV) Cables and Accessories (Terminations
and Splices),'' EPRI Product ID: 1013187; ``Plant Support Engineering:
Aging Management Program Development Guidance for AC and DC Low-Voltage
Power Cable Systems for Nuclear Power Plants,'' EPRI Product ID:
1020804; and ``Plant Support Engineering: Aging Management Program
Guidance for Medium-Voltage Cable Systems for Nuclear Power Plants,''
EPRI Product ID: 1020805. The EPRI documents are available for download
from www.EPRI.com.
Also in support of their request for rulemaking to extend Sec.
50.49 requirements to electrical equipment in mild environments, the
petitioners contended that the NRC's requirements state only that
safety systems should remain functional and do not provide conditions
or acceptance criteria for degraded cables.
NRC Response to Issue 2: The NRC agrees that Sec. 50.49 does not
apply to reactor cables and electrical equipment exposed to mild
environments. This section of the rule applies EQ requirements only to
important to safety cables and electrical equipment that may be exposed
to non-mild environments during accident conditions. The purpose of the
final Sec. 50.49 rule (48 FR 2730; January 21, 1983) was to codify
accepted industry standards and NRC guidance for the EQ of safety-
related electrical equipment, and non-safety-related equipment relied
on by safety-related equipment, that must perform a safety function
under DBE conditions.
The NRC disagrees with the petitioners' assertion that Sec. 50.49
should be amended to extend EQ requirements to important to safety
cables and electrical equipment exposed to submergence or moisture
intrusion in mild environments. The existing rule specifically exempts
from these requirements equipment exposed only to a ``mild
environment,'' which is defined in Sec. 50.49(c) as an environment
that would at no time be significantly more severe than the environment
that would occur during normal plant operation, including anticipated
operational occurrences.
All important to safety equipment whether in mild or non-mild
environments is subject to the requirements for monitoring the
effectiveness of maintanence under the maintenance rule (Sec. 50.65).
Furthermore, all important to safety equipment at plants with
construction permits issued after May 21, 1971, is also subject to the
design and quality requirements in 10 CFR part 50, appendix A. In
addition to the above requirements, all safety-related equipment is
also subject to the quality assurance requirements of 10 CFR part 50,
appendix B. Therefore, equipment in mild environments exposed to
submergence, condensation, and moisture intrusion, the kind of
[[Page 11684]]
degradation of concern to the petitioners, is subject to several
existing requirements. For important to safety equipment that could be
subject to environmental conditions that may result as a consequence of
a DBE, Sec. 50.49 establishes additional requirements beyond those
stipulated in Sec. 50.65; 10 CFR part 50, appendix A; and 10 CFR part
50, appendix B.
The maintenance rule (Sec. 50.65) establishes requirements for
monitoring the effectiveness of maintenance at nuclear power plants.
Under Sec. 50.65(a)(1), licensees are required to monitor the
condition or performance of structures, systems, or components (SSCs)
in a manner providing reasonable assurance that the intended SSC
functions can be fulfilled. Section 50.65(b) describes the types of
SSCs subject to its requirements. The maintenance rule (Sec. 50.65)
applies to safety and non-safety SSCs that includes the following: SSCs
used in the plant's emergency operating procedures or relied upon to
mitigate accidents or transient unsafe conditions; SSCs whose failure
could prevent safety-related SSCs from fulfilling their safety-related
function; or SSCs whose failure could cause a reactor scram (unplanned
action to stop the fission reaction) or the actuation of a safety-
related system. With this scope, the maintenance rule (Sec. 50.65)
already covers the equipment specified in the petition (i.e., all
safety-related cables, wires, splices, connections, and other ancillary
electrical equipment that may be subjected to submergence and/or
moisture intrusion). Section 50.65 covers this equipment under any
normal or unusual operating or post-accident conditions, whether these
conditions include severe weather, seasonal flooding, or seismic
events, or whether the SSCs are inside or outside of containment. The
rule also covers the petitioners' specified systems and components
whether or not they are exposed to submergence in water, condensation,
wetting, and other environmental stresses during routine operation and
infrequent events (e.g., flooding).
In its April 2012 Regulatory Guide (RG) 1.218, ``Condition-
Monitoring Techniques for Electric Cables Used In Nuclear Power
Plants'' (ADAMS Accession No. ML103510447), the NRC described a
programmatic approach and acceptable techniques for monitoring the
condition of electric cable systems and their operating environments.
As authority for this guidance, RG 1.218 cited 10 CFR part 50,
Criterion XI, ``Test Control,'' of appendix B. Criterion XI specifies
that power reactor licensees must have a program to assure that all
testing required to show that SSCs will perform satisfactorily in
service is identified and performed.
The test program must include, as appropriate, operational tests of
SSCs during nuclear power plant operation. Test procedures must include
provisions for assuring that all prerequisites for the given test have
been met, that adequate test instrumentation is available and used, and
that the test is performed under suitable environmental conditions.
Test results under Criterion XI must also be ``documented and
evaluated'' to ensure that this Criterion's requirements have been
satisfied. It is important to note that Criterion XI is only one of 18
criteria that are applicable to a quality assurance program for the
electrical equipment at issue in this petition. Appendix B criteria
establish quality assurance requirements for the design, manufacture,
construction, and operation of all safety-related equipment, and all
activities affecting its functions, including not only testing, but
designing, purchasing, fabricating, handling, shipping, storing,
cleaning, installing, inspecting, operating, maintaining, repairing,
and modifying this equipment. Criterion XVI, ``Corrective Action,''
also requires licensees to have measures assuring that conditions
adverse to quality are promptly identified and corrected. Examples of
such conditions are the following: failures, malfunctions,
deficiencies, deviations, defective material and equipment, and
nonconformances. For significant conditions adverse to quality,
including the potential failure of electrical equipment to function as
designed, licensees must determine the cause of the condition and
``assure'' that corrective action is taken to preclude a repetition of
the adverse condition. The identified condition, its cause, and the
corrective action taken to prevent its recurrence must also be
documented and the appropriate levels of management informed. In
addition, for important to safety cables and electrical equipment
located in an area meeting the definition of a mild environment in
Sec. 50.49, 10 CFR part 50, appendix A, GDC 4 requires that this
equipment be designed to manage the conditions it will experience
during normal operation, maintenance, testing, and postulated
accidents.
The NRC does not agree that its existing regulations do not require
sufficient protection of important to safety electrical equipment
against expected or potential environmental conditions it experiences
during its period of service. Regardless of whether a cable, switch, or
other piece of electrical equipment must be environmentally qualified
under Sec. 50.49, it must meet maintenance, design, and quality
assurance requirements established by Sec. 50.65; 10 CFR part 50,
appendix A; and 10 CFR part 50, appendix B (for safety-related
equipment), to provide adequate protection for public health and
safety. And regardless of whether the equipment is environmentally
qualified, it is subject to the same degree of NRC oversight in the
form of inspections and enforcement. A rulemaking to require the
environmental qualification of all electrical equipment exposed only to
mild environments is, therefore, unnecessary.
Moreover, the 1996 DOE study and three EPRI studies cited by the
petitioners are well known to the NRC and do not constitute significant
new information justifying a rulemaking. The NRC recognized the concern
regarding the reliability of low-voltage power cable systems at
reactors that the petitioner references and acted accordingly. Among
other things, the NRC has revised its inspection procedures to ensure
annual inspections of underground bunkers and manholes in a continuing
repeated cycle beginning with those containing the most risk-
significant cables. The NRC also issued RG 1.218, describing a
programmatic approach and acceptable techniques for monitoring the
condition of electric cable systems and their operating environments.
The NRC disagrees with the petitioners' contention that the NRC's
requirements do not provide conditions or acceptance criteria for
degraded cables. Any requirement for safety-related systems to remain
functional for a specified operating life is a design requirement, and
any failure of the equipment before the end of that operating life
would be a violation of that design requirement. Therefore, taken
together, GDC 2, 4, and 18 in 10 CFR part 50, appendix A, the
maintenance requirements under Sec. 50.65, and the quality assurance
testing requirements in 10 CFR part 50, appendix B, Criterion XI,
effectively provide an enforceable acceptance criterion for the
continued use of cables or any other electrical equipment degrading
during normal operation. Criterion XI states that the measured rate of
degradation must not impair the equipment's ability to function in an
emergency, even if the emergency were to occur on the last day of the
performance period specified in the equipment's design requirement.
[[Page 11685]]
Guidance for the implementation of this criterion is provided in
the August 25, 2009, NRC staff regulatory resolution issue protocol,
``Cable Performance Issues at Nuclear Power Plants'' (ADAMS Accession
No. ML092220419), which the petitioners cited as documentation of the
NRC's requirements on cable and wire submergence issues. The NRC staff
position in that protocol is: (1) Licensees should monitor cables
within the scope of the maintenance rule (Sec. 50.65) at an
appropriate frequency to demonstrate that they can perform their design
functions when called upon; and (2) cables must be designed to fulfill
their intended design function in the environment to which they are
subject. Under the protocol, if cables have been exposed to conditions
for which they are not designed or qualified, the licensee must
demonstrate, through adequate testing or condition monitoring, that the
cables can perform their intended design function for the duration of
the qualified period specified in the license.
The NRC also inspects underground cables through established
inspection procedures. In particular, Inspection Procedure (IP)
Attachment 71111.06, ``Flood Protection Measures'' (ADAMS Accession No.
ML11244A012), specifically directs NRC inspectors to perform an annual
review of cables located in underground bunkers or manholes. The IP
Attachment directs inspectors to select bunkers or manholes subject to
flooding that contain multiple train or multiple risk-significant
cables, and inspect those that contain more risk-significant cables
before inspecting those with less risk-significant cables. The IP notes
that inspectors should rotate through the bunkers or manholes until all
are inspected; and then the cycle should be recommenced. The IP
Attachment also clarifies that these inspections may be in addition to
those for the aging management programs of plants with renewed
licenses. Where ``significant moisture'' is identified at such plants,
inspectors are to verify that the licensee takes action to keep the
cables dry and assess cable degradation in accordance with the
licensee's aging management program.
Issue 3: Although GDC 2 and 4 of the NRC's regulations require that
cables be able to perform their design function when subjected to
anticipated environmental conditions, the NRC does not apply these and
other GDC to the 57 plants with construction permits issued before May
21, 1971, the effective date of the GDC rule (36 FR 3256; February 20,
1971).
Citing the August 25, 2009, NRC staff regulatory issue resolution
protocol, ``Cable Performance Issues at Nuclear Power Plants,'' the
petitioners asserted that this statement defined the NRC's governing
regulations on submerged cable performance as explicitly including GDC
2 and GDC 4. The GDC 2 requires reactor SSCs that are important to
safety be designed to withstand the effects of natural phenomena
without loss of capability to perform their safety functions. The GDC 4
requires that these SSCs be designed to accommodate the effects of and
be compatible with the environmental conditions associated with normal
operation, maintenance, testing, and postulated accidents.
The petition stated that although these GDC may contain appropriate
regulatory requirements for the qualification of electrical cables and
wires, the NRC has determined that these requirements are not to be
applied to the majority of reactors. The petitioners noted that, at the
time the petition was submitted, at least 57 of the nation`s 104
operating reactors had construction permits that were issued prior to
the effective date of the GDC rule, and that the Commission, through
guidance to the NRC staff, has determined that the GDC do not need to
be applied to these 57 reactors.
NRC Response to Issue 3: The NRC disagrees with the petitioners'
suggestion that the 57 plants that received construction permits prior
to May 21, 1971, are not operating safely with appropriately qualified
important to safety equipment. In 1992, after more than 15 years of
analysis, the NRC staff recommended that the Commission retain the
current policy that no exemptions from or specific backfits for the GDC
are required for plants with construction permits issued before that
date. In its September 18, 1992, Staff Requirements Memorandum (SRM)
(ADAMS Accession No. ML003763736), the Commission endorsed the NRC
staff's recommendation not to apply the GDC to plants with construction
permits issued prior to the effective date of the GDC rule. This
recommendation was based on the documented results of the NRC staff's
evaluations of representative designs of 10 of the 57 plants against
the design requirements of a 1975 Standard Review Plan for reactor
license applications based on the approved GDC.
The SRM explained that at the time the GDC were promulgated, the
Commission had stressed that they were not new requirements and were
promulgated to articulate more clearly the licensing requirements and
practice in effect at that time. The Commission stated that while
compliance with the intent of the GDC is important, each plant licensed
before the GDC were formally adopted was evaluated on a plant-specific
basis, determined to be safe, and licensed by the NRC. Furthermore, the
Commission determined that existing regulatory processes were
sufficient to ensure that plants continue to be safe and comply with
the intent of the GDC. As the petitioners also noted, the Commission
went on to say that backfitting these 57 plants to meet the GDC would
provide little or no safety benefit while requiring an extensive
commitment of resources. The petitioners have not provided any
significant, new, or previously unconsidered information to justify a
new rulemaking or to reverse this NRC position.
III. Reasons for Denial
The NRC is denying PRM-50-106 because:
(1) The NRC disagrees with the petitioners' assertion that GL 82-09
has restricted the applicability of Sec. 50.49 regulatory requirements
for safety-related equipment according to its location. This regulation
is applicable to electrical equipment located outside containment as
well as inside.
(2) Section 50.49 explicitly excludes important to safety
electrical equipment subject only to mild environments. The petitioners
have not provided significant new information sufficient to justify a
change to this rule. A rulemaking to require the environmental
qualification of all electrical equipment exposed only to mild
environments is unnecessary because existing NRC regulations require
sufficient protection of important to safety electrical equipment
against expected or potential environmental conditions it experiences
during its period of service.
(3) With regard to the reactors that received construction permits
prior to May 21, 1971, the Commission determined in response to SECY-
92-223, ``Resolution of Deviations Identified During the Systematic
Evaluation Program'' (ADAMS Accession No. ML12256B290) that these
plants are operating safely with appropriately qualified important to
safety equipment, and that no specific backfits of the GDC to these
plants were required. The petitioners have not provided any
significant, new, or previously unconsidered information justifying a
rulemaking to apply the GDC to the 57 reactors that received
construction permits prior to May 21, 1971.
[[Page 11686]]
IV. Conclusion
For the reasons cited in this document, the NRC is denying PRM-50-
106. The NRC is denying this petition because the current regulations
already address environmental qualification in both mild and design
basis event conditions of electrical equipment located both inside and
outside of the containment building that is important to safety, and
the petitioners did not provide significant new or previously
unconsidered information sufficient to justify rulemaking.
Dated at Rockville, Maryland, this 29th day of February, 2016.
For the Nuclear Regulatory Commission.
Annette L. Vietti-Cook,
Secretary of the Commission.
[FR Doc. 2016-05028 Filed 3-4-16; 8:45 am]
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