[Federal Register Volume 72, Number 172 (Thursday, September 6, 2007)]
[Notices]
[Pages 51256-51259]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-17616]


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NUCLEAR REGULATORY COMMISSION


Proposed License Renewal Interim Staff Guidance LR-ISG-2007-02: 
Changes to Generic Aging Lesson Learned (GALL) Report Aging Management 
Program (AMP) XI.E6, ``Electrical Cable Connections Not Subject to 10 
CFR 50.49 Environmental Qualification Requirements'' Solicitation of 
Public Comment

AGENCY: U.S. Nuclear Regulatory Commission.

ACTION: Solicitation of public comment.

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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is soliciting 
public comment on its Proposed License Renewal Interim Staff Guidance 
LR-ISG-2007-02 (LR-ISG) for changes to its Generic Aging Lesson Learned 
(GALL) Report Aging Management Program (AMP) XI.E6, ``Electrical Cable 
Connections Not Subject to 10 CFR 50.49 Environmental Qualification 
Requirements.'' This LR-ISG clarifies and recommends a one-time 
inspection to ensure that either aging of metallic cable connections is 
not occurring or an existing preventive maintenance program is 
effective, such that a periodic inspection is not needed. The NRC staff 
issues LR-ISGs to facilitate timely implementation of the license 
renewal rule and to review activities associated with an LRA. Upon 
receiving public comments, the NRC staff will evaluate the comments and 
make a determination to incorporate the comments, as appropriate. Once 
the NRC staff completes the LR-ISG, it will issue the LR-ISG for NRC 
and industry use. The NRC staff will also incorporate the approved LR-
ISG into the next revision of the license renewal guidance documents.

DATES: Comments may be submitted by October 22, 2007. Comments received 
after this date will be considered, if it is practical to do so, but 
the Commission is able to ensure consideration only for comments 
received on or before this date.

ADDRESSES: Comments may be submitted to: Chief, Rulemaking, Directives, 
and Editing Branch, Office of Administration, U.S. Nuclear Regulatory 
Commission, Washington, DC 20555-0001. Comments should be delivered to: 
11545 Rockville Pike, Rockville, Maryland, Room T-6D59, between 7:30 
a.m. and 4:15 p.m. on Federal workdays. Persons may also provide 
comments via e-mail at [email protected]. The NRC maintains an Agencywide 
Documents Access and Management System (ADAMS), which provides text and 
image files of NRC's public documents. These documents may be accessed 
through the NRC's Public Electronic Reading Room on the Internet at 
http: //www.nrc.gov/reading-rm/adams.html. Persons who do not have 
access to ADAMS or who encounter problems in accessing the documents 
located in ADAMS should contact the NRC Public Document Room (PDR) 
reference staff at 1-800-397-4209, 301-415-4737, or by e-mail at 
[email protected].

FOR FURTHER INFORMATION CONTACT: Ms. Linh Tran, Project Manager, Office 
of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission, 
Washington, DC 20555-0001; telephone 301-415-4103 or by e-mail at 
[email protected].

SUPPLEMENTARY INFORMATION: Attachment 1 to this Federal Register 
notice, entitled Staff Position and Rationale for the Proposed License 
Renewal Interim Staff Guidance LR-ISG-2007-02: Changes to Generic Aging 
Lesson Learned (GALL) Report Aging Management Program (AMP) XI.E6, 
``Electrical Cable Connections Not Subject to 10 CFR 50.49 
Environmental Qualification Requirements,'' contains the NRC staff's 
rationale for publishing the proposed LR-ISG-2007-02. Attachment 2 to 
this Federal Register notice, entitled Proposed License Renewal Interim 
Staff Guidance LR-ISG-2007-02: Changes to Generic Aging Lesson Learned 
(GALL) Report Aging Management Program (AMP) XI.E6, ``Electrical Cable 
Connections Not Subject to 10 CFR 50.49 Environmental Qualification 
Requirements,'' contains the proposed revisions to GALL AMP XI.E6.
    The NRC staff is issuing this notice to solicit public comments on 
the proposed LR-ISG-2007-02. After the NRC staff considers any public 
comments, it will make a determination regarding issuance of the 
proposed LR-ISG.

    Dated at Rockville, Maryland this 29th day of August, 2007.

    For the Nuclear Regulatory Commission.
Pao-Tsin Kuo,
Director, Division of License Renewal, Office of Nuclear Reactor 
Regulation.

Attachment 1--Staff Position and Rationale for the Proposed License 
Renewal Interim Staff Guidance LR-ISG-2007-02: Changes to Generic Aging 
Lesson Learned (GALL) Report Aging Management Program (AMP) XI.E6, 
``Electrical Cable Connections Not Subject to 10 CFR 50.49 
Environmental Qualification Requirements''

Staff Position

    The staff is proposing to revise GALL AMP XI.E6 to recommend a one-
time inspection for electrical cable connections not subject to 10 CFR 
50.49 environmental qualification requirement instead of the period 
inspection as currently stated in GALL AMP XI.E6. The staff determined 
that this one-time inspection, on representative sample basis, is 
adequate to ensure that either aging of metallic cable connections is 
not occurring and/or existing preventive maintenance program is 
effective such that a periodic inspection program is not needed.

Rationale

    In reviewing the industry's documents and comments, the staff 
determined that although the current GALL AMP XI.E6 was based on 
technical bases of Electric Power Research Institute documents, Sandia 
National Laboratories Report, SAND 96-0344, and thermography data, few 
operating experiences related to failed connection due to aging had 
been identified. Most of the operating experience related to failed 
connection are due to human errors or maintenance practices. The 
operating experience cannot support a periodic inspection as currently 
recommended in GALL AMP XI.E6. However, because there have been a 
limited number of age related failures of cable connections, a one-time 
inspection of the metallic portion of electrical cable connections is 
warranted. On this basis, the staff is revising GALL AMP XI.E6 to 
clarify and recommend a one-time inspection, on a representative 
sampling basis, to ensure that either aging of metallic cable 
connections is not occurring or an existing preventive maintenance 
program is effective, such that a periodic inspection is not needed.

[[Page 51257]]

Attachment 2--Proposed License Renewal Interim Staff Guidance LR-ISG-
2007-02: Changes to Generic Aging Lesson Learned (GALL) Report Aging 
Management Program (AMP) XI.E6, ``Electrical Cable Connections Not 
Subject to 10 CFR 50.49 Environmental Qualification Requirements''

Introduction

    Consistent with the requirements specified in Title 10 of the Code 
of Federal Regulations (10 CFR) Part 54, Section 54.4(a), electrical 
cable connections support safety-related and non-safety-related 
functions in that the failure of the electrical cable connections 
precludes a function from being accomplished (10 CFR 54.4(a)(1), 
(a)(2), and (a)(3)).
    Electrical cable connections exposed to appreciable ohmic or 
ambient heating during operation may experience loosening caused by 
repeated cycling of connected loads or of the ambient temperature 
environment. Different materials used in various cable system 
components can produce situations where stresses between these 
components change with repeated thermal cycling. For example, under 
loaded conditions, ohmic heating may raise the temperature of a 
compression terminal and cable conductor well above the ambient 
temperature, thereby causing thermal expansion of both components. 
Thermal expansion coefficients of different materials may alter 
mechanical stresses between the components so that the termination may 
be impacted. When the current is reduced, the affected components cool 
and contract. Repeated cycling in this fashion can cause loosening of 
the termination, and may lead to high electrical resistance or eventual 
separation of compression-type terminations. Threaded connectors may 
loosen if subjected to significant thermally induced stress and 
cycling. Because of the potential loosening of bolted cable 
connections, the staff included, in its updated license renewal 
guidance documents, AMP XI.E6, ``Electrical Cable Connections Not 
Subject to 10 CFR 50.49 Environmental Qualification Requirements,'' to 
manage the potential aging of electrical cable connections not subject 
to 10 CFR 50.49 environmental qualification requirements.

Background and Discussion

    The staff included AMP XI.E6, ``Electrical Cable Connections Not 
Subject to 10 CFR 50.49 Environmental Qualification Requirements,'' in 
Chapter XI of GALL Report, Revision 1, dated September 2005. By letter 
dated September 5, 2006, (Agencywide Documents Access and Management 
System (ADAMS) Accession No. ML062770105), Nuclear Energy Institute 
(NEI) submitted a white paper regarding GALL AMP XI.E6 (ADAMS Accession 
No. ML062770111) . NEI stated that there was not enough operating 
experience to support a conclusion that cable connections are a 
significant aging concern and that the recommended program elements of 
GALL AMP XI.E6 duplicate aging management activities already defined 
and accepted in other AMPs. NEI also stated that the expanded scope of 
the program includes all voltage ranges regardless of the amount of 
evidence from operating experience. In addition, NEI identified wording 
in GALL AMP XI.E6 that included connections in active components. NEI 
asked the staff to review its white paper to eliminate GALL AMP XI.E6 
or minimize its scope and redundancy so that the plant would not be 
burdened with activities that have no actual aging management benefit.
    On November 30, 2006, the staff met with NEI representatives to 
discuss the white paper. In a letter dated March 16, 2007, (ADAMS 
Accession No. ML070400349), the staff provided responses to each of the 
industry's concerns identified in the white paper. By letter dated May 
25, 2007, (ADAMS Accession Nos. ML071590175 and ML071590182), NEI 
submitted comments on the staff's responses.
    In reviewing the industry's white paper and comments, the staff 
determined that although GALL AMP XI.E6 was based on the technical 
bases of Electric Power Research Institute documents, and Sandia 
National Laboratories Report, SAND 96-0344, little operating experience 
related to failed connections due to aging had been identified. Most of 
the operating experience related to failed connections were due to 
human errors or maintenance practices. The operating experience cannot 
support the periodic inspection recommended in AMP XI.E6 in GALL 
Report, Revision 1, dated September 2005. However, because there have 
been a limited number of age related failures of cable connections, a 
one-time inspection of the metallic portion of electrical cable 
connections is warranted. On this basis, the staff is revising GALL AMP 
XI.E6 to clarify and recommend a one-time inspection, on a 
representative sampling, to ensure that either aging of metallic cable 
connections is not occurring or an existing preventive maintenance 
program is effective, such that a periodic inspection is not required.

Proposed Action

    The staff is proposing to revise GALL AMP XI.E6 to recommend a one-
time inspection prior to the period of extended operation for 
electrical cable connections not subject to 10 CFR 50.49 EQ requirement 
instead of the periodic inspection currently stated in GALL AMP XI.E6. 
The staff determined that this one-time inspection, on a representative 
sample basis, is adequate to ensure that either aging of metallic cable 
connections is not occurring and/or the existing preventive maintenance 
program is effective so that a periodic inspection program is not 
required. The one-time inspection verifies that loosening and/or high 
resistance of cable connections due to thermal cycling, ohmic heating, 
electrical transients, vibration, chemical contamination, corrosion, 
and oxidation are not happening and periodic inspections are not 
required. The one-time inspection should include testing of a 
representative sample of the electrical cable connection population 
subject to an aging effect. The sample should include each type of 
electrical cable connection. The following factors shall be considered 
for sampling: voltage level (medium and low voltage), circuit loading 
(high load), and location (high temperature, high humidity, vibration, 
etc.). The technical basis for the sample selection should be 
documented. The one-time inspection will confirm that there are no 
aging effects that require management during the period of extended 
operation.
    The applicant will take corrective actions when acceptance criteria 
are not met. Corrective actions may include, but are not limited to 
sample expansion, increased inspection frequency, and replacement or 
repair of the affected cable connection components.
    When an applicant performs periodic preventive maintenance that 
includes inspection and testing of cable connections, the applicant can 
credit this maintenance activity toward GALL AMP XI.E6. The applicant 
may also revise its preventive maintenance procedures to cover the 
inspection of cable connections to take credit for GALL AMP XI.E6.
    Attached is the proposed revision to GALL AMP XI.E6. Although this 
proposed revision does not convey a change in the regulations or how 
they are being interpreted, it is being provided to facilitate 
preparation of future submittals in support of applications for license 
renewal. This LR-ISG provides a clarification of existing guidance with 
no additional requirements.

[[Page 51258]]

Attachment--XI.E6 Electrical Cable Connections Not Subject to 10 CFR 
50.49 Environmental Qualification Requirements (Revised)

Program Description

    Cable connections are used to connect cable conductors to other 
cable conductors or electrical devices. Connections associated with 
cables within the scope of license renewal are part of this program. 
The most common types of connections used in nuclear power plants are 
splices (butt or bolted), crimp-type ring lugs, connectors, and 
terminal blocks. Most connections involve insulating material and 
metallic parts. This aging management program (AMP) focuses on the 
metallic parts of the electrical cable connections. This program 
provides a one-time inspection, on a sampling basis, to confirm the 
absence of age-related degradation of cable connections due to thermal 
cycling, ohmic heating, electrical transients, vibration, chemical 
contamination, corrosion, and oxidation.
    Generic Aging Lesson Learned (GALL) XI.E1, ``Electrical Cables and 
Connections Not Subject to 10 CFR 50.49 Environmental Qualification 
Requirements,'' manages the aging of insulating material but not the 
metallic parts of the electrical connections. GALL XI.E1 is based on 
only a visual inspection of accessible cables and connections. Visual 
inspection may not be sufficient to detect the aging effects from 
thermal cycling, ohmic heating, electrical transients, vibration, 
chemical contamination, corrosion, and oxidation on the metallic parts 
of cable connections.
    Electrical cable connections exposed to appreciable ohmic or 
ambient heating during operation may experience loosening caused by 
repeated cycling of connected loads or of the ambient temperature 
environment. Different materials used in various cable system 
components can produce situations where stresses between these 
components change with repeated thermal cycling. For example, under 
loaded conditions, ohmic heating may raise the temperature of a 
compression terminal and cable conductor well above the ambient 
temperature, thereby causing thermal expansion of both components. 
Thermal expansion coefficients of different materials may alter 
mechanical stresses between the components so that the termination may 
be impacted. When the current is reduced, the affected components cool 
and contract. Repeated cycling in this fashion can cause loosening of 
the termination, and may lead to high electrical resistance or eventual 
separation of compression-type terminations. Threaded connectors may 
loosen if subjected to significant thermally induced stress and 
cycling.
    Cable connections within the scope of license renewal should be 
tested at least once prior to the period of extended operation to 
provide an indication of the integrity of the cable connections. The 
specific type of test to be performed and is to be a proven test for 
detecting loose connections, such as thermography, contact resistance 
testing, or another appropriate test justified in the application.
    This program, as described, can be thought of as a sampling 
program. The following factors shall be considered for sampling: 
voltage level (medium and low voltage), circuit loading (high loading), 
and location (high temperature, high humidity, vibration, etc.). The 
technical basis for the sample selections should be documented. If an 
unacceptable condition or situation is identified in the selected 
sample, corrective action program will be used to evaluate the 
condition and determine appropriate corrective action.
    SAND 96-0344, ``Aging Management Guidelines for Electrical Cable 
and Terminations,'' indicated loose terminations were identified by 
several plants. The major concern is that the failures of a 
deteriorated cable system (cables, connections including fuse holders, 
and penetrations) that could prevent it from performing its intended 
function. This program is not applicable to cable connections in harsh 
environments since they are already addressed by the requirements of 10 
CFR 50.49. Even though cable connections may not be exposed to harsh 
environments, loosening or high resistance of connection is a concern 
due to aging mechanisms discussed above.

Evaluation and Technical Basis

    1. Scope of Program: External connections terminating at an active 
or passive device are in the scope of this program. Wiring connections 
internal to an active assembly are considered a part of the active 
assembly and therefore are not within the scope of this program. This 
program does not include high-voltage (>35 kV) switchyard connections. 
The cable connections covered under the EQ program are not included in 
the scope of this program.
    2. Preventive Actions: No actions are taken as part of this program 
to prevent or mitigate aging degradation.
    3. Parameters Monitored/Inspected: This program will focus on the 
metallic parts of the connection. The monitoring includes loosening of 
bolted connections or high resistance of cable connections due to 
thermal cycling, ohmic heating, electrical transients, vibration, 
chemical contamination, corrosion, and oxidation. A representative 
sample of electrical cable connections is tested. The following factors 
shall be considered for sampling: voltage level (medium and low 
voltage), circuit loading (high load), and location (high temperature, 
high humidity, vibration, etc.). The technical basis for the sample 
selection is to be documented.
    4. Detection of Aging Effects: A representative sample of 
electrical connections within the scope of license renewal will be 
tested at least once prior to the period of extended operation to 
confirm that there are no aging effects requiring management during the 
period of extended operation. Testing may include thermography, contact 
resistance testing, or other appropriate testing methods without 
removing the connection insulation such as heat shrink tape, sleeving, 
insulating boots, etc. The one-time inspection provides additional 
confirmation to support industry operating experience that shows 
electrical connections have not experienced a high degree of failures, 
and that existing installation and maintenance practices are effective.
    5. Monitoring and Trending: Trending actions are not included as 
part of this program because it is a one-time inspection program.
    6. Acceptance Criteria: The acceptance criteria for each test are 
to be defined for the specific type of test performed and the specific 
type of cable connections tested.
    7. Corrective Actions: If test acceptance criteria are not met, the 
corrective action program will be used to perform an evaluation that 
will consider the extent of the condition, the indications of aging 
effect, and changes to the one-time inspection program. Corrective 
actions may include, but are not limited to sample expansion, increase 
inspection frequency, and replacement or repair of the affected cable 
connection components. As discussed in the appendix to this report, the 
staff finds the requirements of 10 CFR Part 50, Appendix B, acceptable 
to address the corrective actions.
    8. Confirmation Process: As discussed in the appendix to this 
report, the staff finds the requirements of 10 CFR Part 50, Appendix B, 
acceptable to address the confirmation process.
    9. Administrative Controls: As discussed in the appendix to this 
report, the staff finds the requirements of 10

[[Page 51259]]

CFR Part 50, Appendix B, acceptable to address the administrative 
controls.
    10. Operating Experience: Electrical cable connections exposed to 
appreciable ohmic or ambient heating during operation may experience 
loosening caused by repeated cycling of connected loads or of the 
ambient temperature environment. There have been limited number of age 
related failures of cable connections reported. This one-time 
inspection confirms the absence of aging degradation of metallic cable 
connections.

References

EPRI TR-109619, Guideline for the Management of Adverse Localized 
Equipment Environments, Electric Power Research Institute, Palo 
Alto, CA, June 1999.
IEEE Std. P1205-2000, IEEE Guide for Assessing, Monitoring and 
Mitigating Aging Effects on Class 1E Equipment Used in Nuclear Power 
Generating Stations.
NUREG/CR-5643, Insights Gained From Aging Research, U.S. Nuclear 
Regulatory Commission, March 1992.
SAND96-0344, Aging Management Guideline for Commercial Nuclear Power 
Plants--Electrical Cable and Terminations, prepared by Sandia 
National Laboratories for the U.S. Department of Energy, September 
1996.
EPRI TR-104213, Bolted Joint Maintenance & Application Guide, 
Electric Power Research Institute, Palo Alto, CA, December 1995.
Staff's Response to the NEI White Paper on Generic Aging Lessons 
Learned (GALL) Report Aging Management Program (AMP) XI.E6, 
``Electrical Cable Connections Not Subject to 10 CFR 50.49 
Environmental Qualification Requirements,'' dated March 16, 2007 
(ADAMS Accession Number ML070400349)
 [FR Doc. E7-17616 Filed 9-5-07; 8:45 am]
BILLING CODE 7590-01-P