Proposed Generic Communication Inaccessible or Underground Cable Failures That Disable Accident Mitigation Systems, 44127-44130 [05-15124]
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Federal Register / Vol. 70, No. 146 / Monday, August 1, 2005 / Notices
the common defense and security and is
otherwise in the public interest.
Accordingly, by this Order, the
Commission grants an exemption
subject to the stated conditions. The
exemption will become effective after
the State of Utah has incorporated the
above conditions into Envirocare’s
radioactive materials license. In
addition, at that time, the Order
transmitted in December 2003 will no
longer be effective.
Pursuant to the requirements in 10
CFR part 51, the Commission has
prepared an Environmental Assessment
(EA) for the proposed action and has
determined that the granting of this
exemption will have no significant
impacts on the quality of the human
environment. This finding was noticed
in the Federal Register on July 18, 2005
(70 FR 41241).
V
Documents related to this action,
including the application for
amendment and supporting
documentation, will be available
electronically at the NRC’s Electronic
Reading Room at https://www.NRC.gov/
reading-rm/adams.html. From this site,
you can access the NRC’s Agencywide
Document Access and Management
System (ADAMS), which provides text
and image files of NRC’s public
documents. The ADAMS accession
numbers for the documents related to
this notice are: Envirocare’s June 8,
2003, request (ML031950334), the NRC
staff’s July 2005 Environmental
Assessment (ML041200390), and the
NRC staff’s June 2005 SER
(ML041190003).
If you do not have access to ADAMS
or if there are problems in accessing the
documents located in ADAMS, contact
the NRC’s Public Document Room (PDR)
Reference staff at 1–800–397–4209, 301–
415–4737, or by e-mail to pdr@nrc.gov.
These documents may also be viewed
electronically on the public computers
located at the NRC’s PDR, O 1 F21, One
White Flint North, 11555 Rockville
Pike, Rockville, MD 20852. The PDR
reproduction contractor will copy
documents for a fee.
Dated in Rockville, Maryland this 22nd
day of July, 2005.
For the Nuclear Regulatory Commission.
Margaret V. Federline,
Acting Director, Office of Nuclear Material
Safety and Safeguards.
[FR Doc. 05–15123 Filed 7–29–05; 8:45 am]
BILLING CODE 7590–01–P
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NUCLEAR REGULATORY
COMMISSION
Proposed Generic Communication
Inaccessible or Underground Cable
Failures That Disable Accident
Mitigation Systems
Nuclear Regulatory
Commission.
ACTION: Notice of opportunity for public
comment.
AGENCY:
SUMMARY: The U.S. Nuclear Regulatory
Commission (NRC) is proposing to issue
a generic letter (GL) to:
Alert the licensees on the potential
susceptibility of certain cables to affect
the operability of multiple accidentmitigation systems;
Request that addressees provide
information regarding the monitoring of
the inaccessible or underground
electrical cables in light of the
information provided in this letter.
Adequate monitoring will ensure that
cables will not fail abruptly and cause
plant transients or disable accident
mitigation systems when they are
needed;
Require addressees, to submit a
written response to this generic letter
pursuant to 10 CFR 50.54(f).
This Federal Register notice is
available through the NRC’s
Agencywide Documents Access and
Management System (ADAMS) under
accession number ML050880448.
DATES: Comment period expires
September 30, 2005. Comments
submitted after this date will be
considered if it is practical to do so, but
assurance of consideration cannot be
given except for comments received on
or before this date.
ADDRESSES: Submit written comments
to the Chief, Rules and Directives
Branch, Division of Administrative
Services, Office of Administration, U.S.
Nuclear Regulatory Commission, Mail
Stop T6–D59, Washington, DC 20555–
0001, and cite the publication date and
page number of this Federal Register
notice. Written comments may also be
delivered to NRC Headquarters, 11545
Rockville Pike (Room T–6D59),
Rockville, Maryland, between 7:30 a.m.
and 4:15 p.m. on Federal workdays.
FOR FURTHER INFORMATION, CONTACT:
Thomas Koshy at 301–415–1176 or by email txk@nrc.gov.
SUPPLEMENTARY INFORMATION: NRC
Generic Letter 2005–XX, Inaccessible or
Underground Cable Failures that
Disable Accident Mitigation Systems.
Addressees
All holders of operating licenses for
nuclear power reactors, except those
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44127
who have permanently ceased
operations and have certified that fuel
has been permanently removed from the
reactor vessel.
Purpose
The U.S. Nuclear Regulatory
Commission (NRC) is issuing this
generic letter to:
(1) Alert the licensees on the potential
susceptibility of certain cables to affect
the operability of multiple accidentmitigation systems.
(2) Request that addressees provide
information regarding the monitoring of
the inaccessible or underground
electrical cables in light of the
information provided in this letter.
Adequate monitoring will ensure that
cables will not fail abruptly and cause
plant transients or disable accident
mitigation systems when they are
needed.
Pursuant to 10 CFR 50.54(f),
addressees are required to submit a
written response to this generic letter.
Background
Cable failures have a variety of causes:
Manufacturing defects, damage caused
by shipping and installation, and
exposure to electrical transients or
abnormal environmental conditions
during operation. Most of these defects
worsen gradually over time as
insulation degradation leads to cable
failure.
Electrical cables in nuclear power
plants are usually located in dry
environments. However, some cables
are exposed to moisture from
condensation and wetting in
inaccessible locations such as buried
conduits, cable trenches, cable troughs,
duct banks, underground vaults and
direct buried installations. Cables in
these environments can fail due to
various failure mechanisms such as
water treeing (physical degradation),
electrical treeing or other mechanisms
of insulation degradation over varying
voltage levels that decrease the
dielectric strength of the conductor
insulation.
Information Notice (IN) 2002–12
described medium-voltage cable failures
at Oyster Creek and Davis-Besse and
several other plants which experienced
long-term flooding problems in
manholes and duct banks in which
safety related cables were submerged. In
response to the concern identified in IN
2002–12, several plants began manhole
restoration projects to replace faulty
dewatering equipment and cable
supports and made other modifications.
Several other plants have reported water
removal problems but have not yet
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Federal Register / Vol. 70, No. 146 / Monday, August 1, 2005 / Notices
reported any program for the early
detection of potential failures.
The rugged design of the electrical
cables may prevent early failures even
when they have been immersed in water
for extended periods. When the staff
observed that some of the cables
qualified for 40 years through the
equipment qualification program were
also failing at several nuclear stations, a
detailed review was conducted. Even
though there are only about a dozen
cables susceptible for moisture-induced
damage in a nuclear station, the staff
identified 23 Licensee Event Reports
(LERs) and morning reports since 1988
on failures of buried medium-voltage
cables from insulation failure. These
reported events are believed to be only
a very small fraction of the failures since
not all cable failures are reportable. In
most of the reported cases, the failed
cables were in service for 10 years or
more and none of these cables were
identified as designed or qualified for
long-term wetting or submergence.
Applicable Regulatory Requirements
NRC regulations in title 10 of the
Code of Federal Regulations (CFR) part
50, Appendix A, General Design
Criterion (GDC) 4 states that,
‘‘Structures, systems, and components
important to safety shall be designed to
accommodate the effects of and to be
compatible with the environmental
conditions associated with normal
operation[.]’’
10 CFR, part 50, Appendix A, GDC 17
states that, ‘‘Provisions shall be
included to minimize the probability of
losing electric power from any of the
remaining [power] supplies, * * * loss
of power from the transmission
network, or the loss of power from the
onsite electric power supplies.’’
10 CFR, part 50, Appendix A, GDC 18
states that, ‘‘Electric power systems
important to safety shall be designed to
permit appropriate periodic inspection
and testing of important * * * features,
such as wiring, insulation, * * * the
operability of the systems as a whole
and, * * * the transfer of power among
the nuclear power unit, the offsite
power system, and the onsite power
system.’’
10 CFR 50.65(a)(1) states that, ‘‘Each
holder of a license to operate a nuclear
power plant * * * shall monitor the
performance or condition of structures,
systems, or components, * * * in a
manner sufficient to provide reasonable
assurance that such structures, systems,
and components, * * * are capable of
fulfilling their intended functions.’’
10 CFR, part 50, Appendix B,
Criterion XI, requires, ‘‘A test program
shall be established to assure that all
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testing required to demonstrate that
* * * components will perform
satisfactorily in service is identified and
performed[.]’’
These design criteria require that
cables which are routed underground be
capable of performing their function
when subjected to anticipated
environmental conditions such as
moisture or flooding. Further, the design
should minimize the probability of
power interruption when transferring
power between sources. The cable
failures that could disable risksignificant equipment are expected to
have monitoring programs to
demonstrate that the cables can perform
their safety function when called on.
However, the recent industry cable
failure data indicates a trend in
unanticipated failures of underground/
inaccessible cables that are important to
safety.
Discussion
Although nuclear plant systems are
designed against single failures,
undetected degradation of cables due to
pre-existing manufacturing defects or
wetted environments of buried or
inaccessible cables could result in
multiple equipment failures. The
following are examples of risksignificant cable failures:
• The failure of power cables that
connect the offsite power to the safety
bus could result in an inability to
recover offsite power far beyond the
coping time considered for station
blackout conditions. The incipient
failures of these cables can go
undetected because these cables
generally remain de-energized when the
plant is generating power.
• The failure of the power cables from
an emergency diesel generator (EDG) to
the respective safety bus (where the
EDGs are located in separate buildings)
would prevent recovery of standby
power from the respective EDG and
result in the unavailability of a full train
of accident mitigation systems during a
loss-of-offsite-power event (LOOP).
• The failure of the power cables to
an emergency service water (ESW) or
component cooling water pump can
disable one train of emergency core
cooling systems for long-term service
unless the headers can be crossconnected and the redundant pump(s)
can be lined up to supply sufficient
cooling for both trains. If the EDGs are
cooled from ESW or service water, the
cable failure could disable the EDG and
lose one train of standby power.
At the Davis-Besse nuclear station, an
underground cable insulation failure
resulted in the trip of the 13.8kV
circulating water pump breaker and loss
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of power to two other 4kV substations.
The cable showed signs of insulation
degradation caused by moisture
intrusion (Inspection Report No:
05000346/2004017, ADAMS Accession
No: ML050310426, issued on January
30, 2005). Generally, cable failure
results in fault currents several orders of
magnitude over the normal current.
Until isolated by a breaker, the fault
current or transient voltages travel on
the immediate power systems, trip
breakers that operate near their trip
setpoint and fail other degraded
insulation systems.
As cables that are not qualified for
wet environments are exposed to wet
environments, they will continue to
degrade with an increasing possibility
that more than one cable will fail on
demand from a cable fault or a
switching transient. While a single
failure may be manageable, multiple
failures of this kind would pose undue
challenges for the plant operators.
Certain plants have reported failures
in other safety systems such as auxiliary
feedwater and containment spray
systems with AC and DC power and
control cables routed underground or
along other inaccessible paths. Those
degraded cables that are normally
energized may fail to reveal their
degraded condition, and the potential
failure of the de-energized safety
systems might only be revealed during
a demand for the mitigation capability.
Certain licensees have attempted to
periodically drain the accumulated
water from the cable surroundings to
avoid cable failures. In areas where the
water table is relatively close to the
cable, the water refills the cavity soon
after the draining. In other cases, the
water accumulates seasonally during
snow fall or rain, filling the conduit or
raceways, and cables may dry out
whenever the humidity drops. In both
cases, periodic draining may decrease
the rate of insulation degradation but it
does not prevent cable failures.
Potential cable failures can be
detected through state-of-the-art
techniques for measuring and trending
the condition of cable insulation. The
cables that are susceptible to moistureinduced failures may vary from plant to
plant, and they are generally routed in
underground conduits, concrete duct
banks, cable trenches, cable troughs,
underground vaults or direct buried
installations. Selective use of testing
techniques, such as the partial discharge
test, time domain reflectometry,
dissipation factor testing, very low
frequency AC testing, and broadband
impedance spectroscopy, have helped
licensees assess the condition of cable
insulation with reasonable confidence,
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Federal Register / Vol. 70, No. 146 / Monday, August 1, 2005 / Notices
such that cables can be replaced in a
planned way during refueling outages.
The Oconee Nuclear Station relied on
the partial discharge test to monitor the
condition of the emergency power
supply cable insulation and replaced
the cable during a scheduled outage
(Inspection Report 50–269/99–12, 50–
270/99–12, ADAMS Accession No:
ML0036767490 issued on September 21,
1999).
A diagnostic cable test program
provides reasonable confidence that the
cable will perform its intended function.
The frequency of the test should be
commensurate with the observed cable
test results. To avoid unplanned outages
and unanticipated failures, certain
licensees have adopted a baseline
frequency of 5 years for new cables or
more frequent testing when insulation
degradation is observed.
Requested Information
Within 90 days of the date of this
generic letter, addressees are requested
to provide the following information to
the NRC:
(1) Provide a history of inaccessible or
underground cable failures, that are
within the scope of 10 CFR 50.65 (the
Maintenance Rule), for all voltage levels
indicating the type, voltage class, years
of service and the root causes for the
failure.
(2) Provide a description and
frequency of all inspection, testing and
monitoring programs, including
surveillance programs, to detect
degradation of inaccessible or
underground cables used to support
EDGs, offsite power, emergency service
water, service water, component cooling
water and other systems that are within
the scope of 10 CFR 50.65 (the
Maintenance Rule).
(3) If a program as described in (2) is
not in place, explain why you believe
such a program is not necessary.
The required written response should
be addressed to the U.S. Nuclear
Regulatory Commission, ATTN:
Document Control Desk, 11555
Rockville Pike, Rockville, Maryland
20852, under oath or affirmation under
the provisions of Section 182a of the
Atomic Energy Act of 1954, as amended,
and 10 CFR 50.54(f). In addition, a copy
of the response should be sent to the
appropriate regional administrator.
Required Response
In accordance with 10 CFR 50.54(f),
addressees are required to submit
written responses to this generic letter.
There are two options:
(a) Addressees may choose to submit
written responses providing the
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information requested above within the
requested time period.
(b) Addressees who cannot meet the
requested completion date or who
choose an alternate course of action are
required to notify the NRC of these
circumstances in writing as soon as
possible but no later than 60 days from
the date of this generic letter. The
response must address any alternative
course of action proposed, and the basis
for the acceptability of the proposed
alternative course of action.
Reasons for Requested Information
This generic letter requests addressees
to submit information. The requested
information will enable the NRC staff to
determine whether applicable
requirements (10 CFR part 50, Appendix
A, General Design Criteria 4, 17 and 18;
10 CFR 50.65, and 10 CFR part 50,
Appendix B, Criterion XI) are being met
in regard to the operational readiness of
the power system and accident
mitigation systems and whether
additional action is necessary on those
topics. The staff considers 40 hours of
information collection burden to be
reasonable in light of the benefit gained
to identify and correct unanticipated
failures of accident mitigation systems.
Backfit Discussion
Under the provisions of section 182a
of the Atomic Energy Act of 1954, as
amended, and 10 CFR 50.54(f), this
generic letter transmits an information
request for the purpose of verifying
compliance with applicable existing
requirements. Specifically, the
requested information will enable the
NRC staff to determine whether
applicable requirements (plant
Technical Specification in conjunction
with 10 CFR part 50, Appendix A,
General Design Criteria 4, 17 and 18; 10
CFR 50.65, and 10 CFR part 50,
Appendix B Criterion XI) are being met
in regard to the operation readiness of
the power system. No backfit is either
intended or approved in the context of
issuance of this generic letter. Therefore,
the staff has not performed a backfit
analysis.
Federal Register Notification
A notice of opportunity for public
comment on this generic letter was
published in the Federal Register on (xx
Frxxxxx) on {date}. Comments were
received from {indicate no of
commentors by type}. The staff
considered all comments that were
received. The staff’s evaluation of the
comments is publicly available through
the NRC’s ADAMS under Accession No.
ML052020036.
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44129
Paperwork Reduction Act Statement
This generic letter contains
information collection requirements that
are subject to the Paperwork Reduction
Act of 1995 (44 U.S.C. 3501 et seq.).
These information collections were
approved by the Office of Management
and Budget, approval No: 3150–0011,
which expires on February 28, 2007.
The burden to the public for these
mandatory information collections is
estimated to average 40 hours per
response, including the time for
reviewing instructions, searching
existing data sources, gathering and
maintaining the data needed, and
completing and reviewing the
information collection. The U.S.
Nuclear Regulatory Commission is
seeking public comment on the
potential impact of the information
collection contained in the generic letter
and on the following issues:
1. Is the proposed information
collection necessary for the proper
performance of the functions of the
NRC, including whether the information
will have practical utility?
2. Is the estimate of burden accurate?
3. Is there a way to enhance the
quality, utility, and clarity of the
information to be collected?
4. How can the burden of the
information collection be minimized,
including the use of automated
collection techniques?
Send comments regarding this burden
estimate or any other aspect of these
information collections, including
suggestions for reducing the burden, to
the Records and FOIA/Privacy Services
Branch (T–5 F52), U.S. Nuclear
Regulatory Commission, Washington,
DC 20555–0001, or by Internet
electronic mail to infocollects@nrc.gov;
and to the Desk Officer, Office of
Information and Regulatory Affairs,
NEOB–10202, (3150–0011), Office of
Management and Budget, Washington,
DC 20503.
Public Protection Notification
The NRC may not conduct or sponsor,
and a person is not required to respond
to, a request for information or an
information collection requirement
unless the requesting document
displays a currently valid OMB control
number.
Contacts
Please direct any questions about this
matter to the technical contact listed
below or the appropriate Office of
Nuclear Reactor Regulation (NRR)
project manager. Bruce A. Boger,
Director, Division of Inspection Program
Management, Office of Nuclear Reactor
Regulation.
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Federal Register / Vol. 70, No. 146 / Monday, August 1, 2005 / Notices
Technical Contact: Thomas Koshy,
NRR, 301–415–1176. E-mail:
txk@nrc.gov.
End of Draft Generic Letter
Documents may be examined, and/or
copied for a fee, at the NRC’s Public
Document Room at One White Flint
North, 11555 Rockville Pike (first floor),
Rockville, Maryland. Publicly available
records will be accessible electronically
from the Agencywide Documents
Access and Management System
(ADAMS) Public Electronic Reading
Room on the Internet at the NRC Web
site, https://www.nrc.gov/NRC/ADAMS/
index.html. If you do not have access to
ADAMS or if you have problems in
accessing the documents in ADAMS,
contact the NRC Public Document Room
(PDR) reference staff at 1–800–397–4209
or 301–415–4737 or by e-mail to
pdr@nrc.gov.
Dated in Rockville, Maryland, this 22nd
day of July 2005.
For the Nuclear Regulatory Commission.
Patrick L. Hiland,
Chief, Reactor Operations Branch, Division
of Inspection Program Management, Office
of Nuclear Reactor Regulation.
[FR Doc. 05–15124 Filed 7–29–05; 8:45 am]
BILLING CODE 7590–01–P
OFFICE OF MANAGEMENT AND
BUDGET
Executive Office of the President;
Performance of Commercial Activities
Office of Management and
Budget (OMB), Executive Office of the
President.
ACTION: Update to Federal Pay Raise
Assumptions, Inflation Factors, and
Costing Software Used in OMB Circular
No. A–76, ‘‘Performance of Commercial
Activities.’’
AGENCY:
SUMMARY: OMB is updating the annual
federal pay raise assumptions and
inflation cost factors used for computing
the government’s personnel and nonpay costs in public-private competitions
conducted pursuant to Office of
Management and Budget (OMB)
Circular A–76. These annual pay raise
assumptions and inflation factors are
based on the President’s Budget for
Fiscal Year 2006. OMB is also providing
notice of an update to ‘‘COMPARE,’’ the
costing software agencies use when
conducting public-private competitions.
DATES: Effective date: These changes are
effective immediately and shall apply to
all public-private competitions
performed in accordance with OMB
Circular A–76, as revised in May 2003,
where the performance decision has not
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been certified by the government before
this date.
FOR FURTHER INFORMATION CONTACT:
Mathew Blum, Office of Federal
Procurement Policy (OFPP), NEOB,
Room 9013, Office of Management and
Budget, 725 17th Street, NW.,
Washington, DC 20503, Tel. No. 202–
395–4953.
Availability: Copies of OMB Circular
A–76 may be obtained on the Internet at
the OMB home page at
www.whitehouse.gov/omb/circulars/
index.html#numerical. Paper copies of
the Circular may be obtained by calling
OFPP (tel: (202) 395–7579). The
COMPARE software may be accessed at
https://www.compareA76.com.
Joshua B. Bolten,
Director.
Memorandum for the Heads of
Executive Departments and Agencies
From: Joshua B. Bolten, Director.
Subject: Update of Annual Federal
Pay Raise Assumptions, Certain
Inflation Factors, and Costing Software
Used in OMB Circular A–76,
Performance of Commercial Activities.
This memorandum updates the
annual federal pay raise assumptions
and inflation cost factors used for
computing the government’s personnel
and non-pay costs in public-private
competitions conducted pursuant to
Office of Management and Budget
(OMB) Circular A–76. These annual pay
raise assumptions and inflation factors
are based on the President’s Budget for
Fiscal Year 2006. The memorandum
also provides notice of an update to
‘‘COMPARE.’’ COMPARE is the
software agencies use to calculate costs
and document performance decisions in
public-private competitions.
1. Federal pay raise assumptions. The
following Federal pay raise assumptions
(including geographic pay differentials)
that are in effect for 2005 shall be used
for the development of government
personnel costs. The pay raise factors
provided for 2006 and beyond shall be
applied to all government personnel
with no assumption being made as to
how they will be distributed between
possible locality and base pay increases.
FEDERAL PAY RAISE ASSUMPTIONS*—
Continued
Effective date
January 2006 ........
Civilian
(percent)
Military
(percent)
2.3
3.1
* Federal pay raise assumptions have not
been established for pay raises subsequent to
January 2006. For January 2007 and beyond,
the projected percentage change in the Employment Cost Index (ECI), 4.2 percent should
be used to estimate government personnel
costs for public-private competitions. In future
updates to cost factors in the Circular, as pay
policy for years subsequent to 2006 is established, these pay raise assumptions will be
revised.
2. Inflation factors. The following
non-pay inflation cost factors are
provided for purposes of public-private
competitions conducted pursuant to
Circular A–76 only. They reflect the
generic non-pay inflation assumptions
used to develop the fiscal year 2006
budget baseline estimates required by
law. The law requires that a specific
inflation factor (GDP FY/FY chained
price index) be used for this purpose.
These inflation factors should not be
viewed as estimates of expected
inflation rates for major long-term
procurement items or as an estimate of
inflation for any particular agency’s
non-pay purchases mix.
NON-PAY CATEGORIES
[Supplies, equipment, etc.]
(percent)
FY
FY
FY
FY
FY
FY
2005
2006
2007
2008
2008
2010
......................................
......................................
......................................
......................................
......................................
......................................
2.0
2.0
2.1
2.1
2.1
*2.1
* Any subsequent years included in the period of performance shall continue to use the
2.1% figure, until otherwise revised by OMB.
3. COMPARE Update. Revisions to
Circular A–76, issued by OMB in May
2003, require agencies to use
‘‘COMPARE’’ when calculating costs in
public-private competitions. This
software incorporates the costing
procedures of the revised Circular to
ensure all agencies calculate and
document the costs of public and
private sector performance in a
standardized manner when conducting
public-private competitions under the
Circular. The Department of Defense
(DOD) maintains COMPARE on OMB’s
FEDERAL PAY RAISE ASSUMPTIONS*
behalf.
DOD has completed a version update
Civilian
Military
Effective date
to COMPARE. COMPARE Version 2.1:
(percent)
(percent)
(1) Improves the functionality of the
January 2005 ........
3.5
3.5 software, (2) applies updated tax rate
information (i.e., from the updated tax
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]]>Agencies
[Federal Register Volume 70, Number 146 (Monday, August 1, 2005)]
[Notices]
[Pages 44127-44130]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-15124]
-----------------------------------------------------------------------
NUCLEAR REGULATORY COMMISSION
Proposed Generic Communication Inaccessible or Underground Cable
Failures That Disable Accident Mitigation Systems
AGENCY: Nuclear Regulatory Commission.
ACTION: Notice of opportunity for public comment.
-----------------------------------------------------------------------
SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is proposing to
issue a generic letter (GL) to:
Alert the licensees on the potential susceptibility of certain
cables to affect the operability of multiple accident-mitigation
systems;
Request that addressees provide information regarding the
monitoring of the inaccessible or underground electrical cables in
light of the information provided in this letter. Adequate monitoring
will ensure that cables will not fail abruptly and cause plant
transients or disable accident mitigation systems when they are needed;
Require addressees, to submit a written response to this generic
letter pursuant to 10 CFR 50.54(f).
This Federal Register notice is available through the NRC's
Agencywide Documents Access and Management System (ADAMS) under
accession number ML050880448.
DATES: Comment period expires September 30, 2005. Comments submitted
after this date will be considered if it is practical to do so, but
assurance of consideration cannot be given except for comments received
on or before this date.
ADDRESSES: Submit written comments to the Chief, Rules and Directives
Branch, Division of Administrative Services, Office of Administration,
U.S. Nuclear Regulatory Commission, Mail Stop T6-D59, Washington, DC
20555-0001, and cite the publication date and page number of this
Federal Register notice. Written comments may also be delivered to NRC
Headquarters, 11545 Rockville Pike (Room T-6D59), Rockville, Maryland,
between 7:30 a.m. and 4:15 p.m. on Federal workdays.
FOR FURTHER INFORMATION, CONTACT: Thomas Koshy at 301-415-1176 or by e-
mail txk@nrc.gov.
SUPPLEMENTARY INFORMATION: NRC Generic Letter 2005-XX, Inaccessible or
Underground Cable Failures that Disable Accident Mitigation Systems.
Addressees
All holders of operating licenses for nuclear power reactors,
except those who have permanently ceased operations and have certified
that fuel has been permanently removed from the reactor vessel.
Purpose
The U.S. Nuclear Regulatory Commission (NRC) is issuing this
generic letter to:
(1) Alert the licensees on the potential susceptibility of certain
cables to affect the operability of multiple accident-mitigation
systems.
(2) Request that addressees provide information regarding the
monitoring of the inaccessible or underground electrical cables in
light of the information provided in this letter. Adequate monitoring
will ensure that cables will not fail abruptly and cause plant
transients or disable accident mitigation systems when they are needed.
Pursuant to 10 CFR 50.54(f), addressees are required to submit a
written response to this generic letter.
Background
Cable failures have a variety of causes: Manufacturing defects,
damage caused by shipping and installation, and exposure to electrical
transients or abnormal environmental conditions during operation. Most
of these defects worsen gradually over time as insulation degradation
leads to cable failure.
Electrical cables in nuclear power plants are usually located in
dry environments. However, some cables are exposed to moisture from
condensation and wetting in inaccessible locations such as buried
conduits, cable trenches, cable troughs, duct banks, underground vaults
and direct buried installations. Cables in these environments can fail
due to various failure mechanisms such as water treeing (physical
degradation), electrical treeing or other mechanisms of insulation
degradation over varying voltage levels that decrease the dielectric
strength of the conductor insulation.
Information Notice (IN) 2002-12 described medium-voltage cable
failures at Oyster Creek and Davis-Besse and several other plants which
experienced long-term flooding problems in manholes and duct banks in
which safety related cables were submerged. In response to the concern
identified in IN 2002-12, several plants began manhole restoration
projects to replace faulty dewatering equipment and cable supports and
made other modifications. Several other plants have reported water
removal problems but have not yet
[[Page 44128]]
reported any program for the early detection of potential failures.
The rugged design of the electrical cables may prevent early
failures even when they have been immersed in water for extended
periods. When the staff observed that some of the cables qualified for
40 years through the equipment qualification program were also failing
at several nuclear stations, a detailed review was conducted. Even
though there are only about a dozen cables susceptible for moisture-
induced damage in a nuclear station, the staff identified 23 Licensee
Event Reports (LERs) and morning reports since 1988 on failures of
buried medium-voltage cables from insulation failure. These reported
events are believed to be only a very small fraction of the failures
since not all cable failures are reportable. In most of the reported
cases, the failed cables were in service for 10 years or more and none
of these cables were identified as designed or qualified for long-term
wetting or submergence.
Applicable Regulatory Requirements
NRC regulations in title 10 of the Code of Federal Regulations
(CFR) part 50, Appendix A, General Design Criterion (GDC) 4 states
that, ``Structures, systems, and components important to safety shall
be designed to accommodate the effects of and to be compatible with the
environmental conditions associated with normal operation[.]''
10 CFR, part 50, Appendix A, GDC 17 states that, ``Provisions shall
be included to minimize the probability of losing electric power from
any of the remaining [power] supplies, * * * loss of power from the
transmission network, or the loss of power from the onsite electric
power supplies.''
10 CFR, part 50, Appendix A, GDC 18 states that, ``Electric power
systems important to safety shall be designed to permit appropriate
periodic inspection and testing of important * * * features, such as
wiring, insulation, * * * the operability of the systems as a whole
and, * * * the transfer of power among the nuclear power unit, the
offsite power system, and the onsite power system.''
10 CFR 50.65(a)(1) states that, ``Each holder of a license to
operate a nuclear power plant * * * shall monitor the performance or
condition of structures, systems, or components, * * * in a manner
sufficient to provide reasonable assurance that such structures,
systems, and components, * * * are capable of fulfilling their intended
functions.''
10 CFR, part 50, Appendix B, Criterion XI, requires, ``A test
program shall be established to assure that all testing required to
demonstrate that * * * components will perform satisfactorily in
service is identified and performed[.]''
These design criteria require that cables which are routed
underground be capable of performing their function when subjected to
anticipated environmental conditions such as moisture or flooding.
Further, the design should minimize the probability of power
interruption when transferring power between sources. The cable
failures that could disable risk-significant equipment are expected to
have monitoring programs to demonstrate that the cables can perform
their safety function when called on. However, the recent industry
cable failure data indicates a trend in unanticipated failures of
underground/inaccessible cables that are important to safety.
Discussion
Although nuclear plant systems are designed against single
failures, undetected degradation of cables due to pre-existing
manufacturing defects or wetted environments of buried or inaccessible
cables could result in multiple equipment failures. The following are
examples of risk-significant cable failures:
The failure of power cables that connect the offsite power
to the safety bus could result in an inability to recover offsite power
far beyond the coping time considered for station blackout conditions.
The incipient failures of these cables can go undetected because these
cables generally remain de-energized when the plant is generating
power.
The failure of the power cables from an emergency diesel
generator (EDG) to the respective safety bus (where the EDGs are
located in separate buildings) would prevent recovery of standby power
from the respective EDG and result in the unavailability of a full
train of accident mitigation systems during a loss-of-offsite-power
event (LOOP).
The failure of the power cables to an emergency service
water (ESW) or component cooling water pump can disable one train of
emergency core cooling systems for long-term service unless the headers
can be cross-connected and the redundant pump(s) can be lined up to
supply sufficient cooling for both trains. If the EDGs are cooled from
ESW or service water, the cable failure could disable the EDG and lose
one train of standby power.
At the Davis-Besse nuclear station, an underground cable insulation
failure resulted in the trip of the 13.8kV circulating water pump
breaker and loss of power to two other 4kV substations. The cable
showed signs of insulation degradation caused by moisture intrusion
(Inspection Report No: 05000346/2004017, ADAMS Accession No:
ML050310426, issued on January 30, 2005). Generally, cable failure
results in fault currents several orders of magnitude over the normal
current. Until isolated by a breaker, the fault current or transient
voltages travel on the immediate power systems, trip breakers that
operate near their trip setpoint and fail other degraded insulation
systems.
As cables that are not qualified for wet environments are exposed
to wet environments, they will continue to degrade with an increasing
possibility that more than one cable will fail on demand from a cable
fault or a switching transient. While a single failure may be
manageable, multiple failures of this kind would pose undue challenges
for the plant operators.
Certain plants have reported failures in other safety systems such
as auxiliary feedwater and containment spray systems with AC and DC
power and control cables routed underground or along other inaccessible
paths. Those degraded cables that are normally energized may fail to
reveal their degraded condition, and the potential failure of the de-
energized safety systems might only be revealed during a demand for the
mitigation capability.
Certain licensees have attempted to periodically drain the
accumulated water from the cable surroundings to avoid cable failures.
In areas where the water table is relatively close to the cable, the
water refills the cavity soon after the draining. In other cases, the
water accumulates seasonally during snow fall or rain, filling the
conduit or raceways, and cables may dry out whenever the humidity
drops. In both cases, periodic draining may decrease the rate of
insulation degradation but it does not prevent cable failures.
Potential cable failures can be detected through state-of-the-art
techniques for measuring and trending the condition of cable
insulation. The cables that are susceptible to moisture-induced
failures may vary from plant to plant, and they are generally routed in
underground conduits, concrete duct banks, cable trenches, cable
troughs, underground vaults or direct buried installations. Selective
use of testing techniques, such as the partial discharge test, time
domain reflectometry, dissipation factor testing, very low frequency AC
testing, and broadband impedance spectroscopy, have helped licensees
assess the condition of cable insulation with reasonable confidence,
[[Page 44129]]
such that cables can be replaced in a planned way during refueling
outages. The Oconee Nuclear Station relied on the partial discharge
test to monitor the condition of the emergency power supply cable
insulation and replaced the cable during a scheduled outage (Inspection
Report 50-269/99-12, 50-270/99-12, ADAMS Accession No: ML0036767490
issued on September 21, 1999).
A diagnostic cable test program provides reasonable confidence that
the cable will perform its intended function. The frequency of the test
should be commensurate with the observed cable test results. To avoid
unplanned outages and unanticipated failures, certain licensees have
adopted a baseline frequency of 5 years for new cables or more frequent
testing when insulation degradation is observed.
Requested Information
Within 90 days of the date of this generic letter, addressees are
requested to provide the following information to the NRC:
(1) Provide a history of inaccessible or underground cable
failures, that are within the scope of 10 CFR 50.65 (the Maintenance
Rule), for all voltage levels indicating the type, voltage class, years
of service and the root causes for the failure.
(2) Provide a description and frequency of all inspection, testing
and monitoring programs, including surveillance programs, to detect
degradation of inaccessible or underground cables used to support EDGs,
offsite power, emergency service water, service water, component
cooling water and other systems that are within the scope of 10 CFR
50.65 (the Maintenance Rule).
(3) If a program as described in (2) is not in place, explain why
you believe such a program is not necessary.
The required written response should be addressed to the U.S.
Nuclear Regulatory Commission, ATTN: Document Control Desk, 11555
Rockville Pike, Rockville, Maryland 20852, under oath or affirmation
under the provisions of Section 182a of the Atomic Energy Act of 1954,
as amended, and 10 CFR 50.54(f). In addition, a copy of the response
should be sent to the appropriate regional administrator.
Required Response
In accordance with 10 CFR 50.54(f), addressees are required to
submit written responses to this generic letter. There are two options:
(a) Addressees may choose to submit written responses providing the
information requested above within the requested time period.
(b) Addressees who cannot meet the requested completion date or who
choose an alternate course of action are required to notify the NRC of
these circumstances in writing as soon as possible but no later than 60
days from the date of this generic letter. The response must address
any alternative course of action proposed, and the basis for the
acceptability of the proposed alternative course of action.
Reasons for Requested Information
This generic letter requests addressees to submit information. The
requested information will enable the NRC staff to determine whether
applicable requirements (10 CFR part 50, Appendix A, General Design
Criteria 4, 17 and 18; 10 CFR 50.65, and 10 CFR part 50, Appendix B,
Criterion XI) are being met in regard to the operational readiness of
the power system and accident mitigation systems and whether additional
action is necessary on those topics. The staff considers 40 hours of
information collection burden to be reasonable in light of the benefit
gained to identify and correct unanticipated failures of accident
mitigation systems.
Backfit Discussion
Under the provisions of section 182a of the Atomic Energy Act of
1954, as amended, and 10 CFR 50.54(f), this generic letter transmits an
information request for the purpose of verifying compliance with
applicable existing requirements. Specifically, the requested
information will enable the NRC staff to determine whether applicable
requirements (plant Technical Specification in conjunction with 10 CFR
part 50, Appendix A, General Design Criteria 4, 17 and 18; 10 CFR
50.65, and 10 CFR part 50, Appendix B Criterion XI) are being met in
regard to the operation readiness of the power system. No backfit is
either intended or approved in the context of issuance of this generic
letter. Therefore, the staff has not performed a backfit analysis.
Federal Register Notification
A notice of opportunity for public comment on this generic letter
was published in the Federal Register on (xx Frxxxxx) on {date{time} .
Comments were received from {indicate no of commentors by type{time} .
The staff considered all comments that were received. The staff's
evaluation of the comments is publicly available through the NRC's
ADAMS under Accession No. ML052020036.
Paperwork Reduction Act Statement
This generic letter contains information collection requirements
that are subject to the Paperwork Reduction Act of 1995 (44 U.S.C. 3501
et seq.). These information collections were approved by the Office of
Management and Budget, approval No: 3150-0011, which expires on
February 28, 2007.
The burden to the public for these mandatory information
collections is estimated to average 40 hours per response, including
the time for reviewing instructions, searching existing data sources,
gathering and maintaining the data needed, and completing and reviewing
the information collection. The U.S. Nuclear Regulatory Commission is
seeking public comment on the potential impact of the information
collection contained in the generic letter and on the following issues:
1. Is the proposed information collection necessary for the proper
performance of the functions of the NRC, including whether the
information will have practical utility?
2. Is the estimate of burden accurate?
3. Is there a way to enhance the quality, utility, and clarity of
the information to be collected?
4. How can the burden of the information collection be minimized,
including the use of automated collection techniques?
Send comments regarding this burden estimate or any other aspect of
these information collections, including suggestions for reducing the
burden, to the Records and FOIA/Privacy Services Branch (T-5 F52), U.S.
Nuclear Regulatory Commission, Washington, DC 20555-0001, or by
Internet electronic mail to infocollects@nrc.gov; and to the Desk
Officer, Office of Information and Regulatory Affairs, NEOB-10202,
(3150-0011), Office of Management and Budget, Washington, DC 20503.
Public Protection Notification
The NRC may not conduct or sponsor, and a person is not required to
respond to, a request for information or an information collection
requirement unless the requesting document displays a currently valid
OMB control number.
Contacts
Please direct any questions about this matter to the technical
contact listed below or the appropriate Office of Nuclear Reactor
Regulation (NRR) project manager. Bruce A. Boger, Director, Division of
Inspection Program Management, Office of Nuclear Reactor Regulation.
[[Page 44130]]
Technical Contact: Thomas Koshy, NRR, 301-415-1176. E-mail:
txk@nrc.gov.
End of Draft Generic Letter
Documents may be examined, and/or copied for a fee, at the NRC's
Public Document Room at One White Flint North, 11555 Rockville Pike
(first floor), Rockville, Maryland. Publicly available records will be
accessible electronically from the Agencywide Documents Access and
Management System (ADAMS) Public Electronic Reading Room on the
Internet at the NRC Web site, https://www.nrc.gov/NRC/ADAMS/.
If you do not have access to ADAMS or if you have problems in accessing
the documents in ADAMS, contact the NRC Public Document Room (PDR)
reference staff at 1-800-397-4209 or 301-415-4737 or by e-mail to
pdr@nrc.gov.
Dated in Rockville, Maryland, this 22nd day of July 2005.
For the Nuclear Regulatory Commission.
Patrick L. Hiland,
Chief, Reactor Operations Branch, Division of Inspection Program
Management, Office of Nuclear Reactor Regulation.
[FR Doc. 05-15124 Filed 7-29-05; 8:45 am]
BILLING CODE 7590-01-P
