ML082530230
| ML082530230 | |
| Person / Time | |
|---|---|
| Issue date: | 04/13/2009 |
| From: | Office of Nuclear Regulatory Research |
| To: | |
| Orr M P/RES/301-415-6373 | |
| Shared Package | |
| ML081640141 | List: |
| References | |
| DG-1132, RG-1.211 | |
| Download: ML082530230 (20) | |
Text
Response to Public Comments for Draft Regulatory Guide DG-1132, Qualification of Safety-Related Cables and Field Splices for Nuclear Power Plants Proposed New Regulatory Guide (RG) 1.211 A notice that Draft Regulatory Guide DG-1132 (proposed new Regulatory Guide 1.211) was available for public comment was published in the Federal Register (72 FR 38845) on Monday, July 16, 2007. The public comment period was closed on September 16, 2007. Comments were received from the five organizations identified below. The NRC has combined the comments and NRC staff disposition in the following table.
Comments were received from:
J. A. Greshman, Manager J. Scott Malcolm, Chair, William A. Horin, Counsel Regulatory Compliance and Plant Licensing Nuclear Power Engineering Committee Nuclear Utility Group on Equipment Westinghouse Electric Co. IEEE Power Engineering Society (IEEE-PES) Qualification (NUGEQ)
Pittsburgh, PA Mississauga, Ontario Washington, DC ADAMS Accession No. ML0725304720 ADAMS Accession No. ML072630389 ADAMS Accession No. ML072630390 Thomas P. Harrall, Jr., Vice President David P. Helker, Manager - Licensing Plant Support Nuclear Generation AmerGen Energy Co., LLC Duke Energy Exelon Nuclear Charlotte, NC Warrenville, IL ADAMS Accession No. ML072630391 ADAMS Accession No. ML072820281 Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 Westinghouse Section B, DG-1132, Section B, Page 2, fourth paragraph states that power and Regulatory Position was clarified.
Page 2, instrumentation and control (I&C) cables for which failures could disable fourth risk-significant equipment should have condition monitoring programs to Suitable techniques for condition paragraph demonstrate that the cables can perform their safety function when needed. monitoring for cables should be A condition monitoring program does not demonstrate that the cables can incorporated in a maintenance program in perform their safety related function; that is the purpose of qualification a nuclear power plant to maintain and testing. Condition monitoring programs are used to assess the physical and demonstrate qualification throughout its operating condition of the cabling. The qualification program qualified life.
demonstrates that the cables will perform their required safety-related function at the end of qualified life under design basis accident (DBA) conditions.
April 13, 2009 1
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 Conditioning monitoring can be used to support aging assessments in conjunction with monitoring temperature and radiation. Condition monitoring can be used to determine if qualified equipment is suitable for further service based on its installed conditions. Usually when condition monitoring is applied one or more condition indicators are monitored to determine whether equipment remains in a qualified condition. As the qualified equipment approaches the end of its demonstrated qualified life, condition monitoring results may be used to determine if an extension of qualified life is possible. When condition monitoring technologies become proven and commercially available then they can become part of the plant maintenance/ surveillance program implemented by the utility.
Conditioning monitoring should not be required as part of the EQ program, rather it should be part of the plant maintenance/surveillance program.
Westinghouse recommends deleting the last sentence of the fourth paragraph or revising it to clarify the purpose of a condition monitoring program. Also, Regulatory Position C(2)(c) should be deleted or clarified.
Westinghouse Regulatory Regulatory Positions C(2)(a) and C(2)(b) request supplements to Clause 4 Regulatory Positions 2(a) and 2(b) in Positions of IEEE Std 383-2003. These positions are already included in IEEEE Std Section C were deleted.
C(2)(a) and 383-2003, Clause 4. These exceptions should be deleted.
C(2)(b)
Westinghouse Regulatory Regulatory Position C(10) should be deleted. Condition monitoring does It is not the intent that a condition-Position C(10) not demonstrate that the cables can perform their safety-related function. monitoring program will replace See Item I above. qualification testing. The word demonstrate was replaced with the word ensure.
A condition-monitoring program is useful to confirm basic assumptions of the qualification program concerning normal environment. Cable aging for the normal operating conditions is usually performed April 13, 2009 2
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 by subjecting new cable to artificial thermal aging in an oven for a time period determined by an Arrhenius extrapolation.
Radiation also is applied as appropriate.
Additional stressors such as manufacturing impurities, installation errors, unanticipated environment, or operating conditions are not considered in the qualification program.
See the additional discussion on condition monitoring under Regulatory Position 10.
IEEE - PES Section B - In addition, power and Instrumentation and control cables for which Revision 1 of Regulatory Guide 1.89, Discussion failures could disable risk - significant equipment should have condition Environmental Qualification of Certain monitoring programs to determine that the cables can perform their Electric Equipment Important to Safety for function when needed." Nuclear Power Plants dated June 1984 states the following: ....qualification is IEEE Comment: IEEE 383-2003 asserts that type testing is adequate to a verification of design limited to ensure that cable and field splices will perform their intended functions demonstrating that the electric equipment during and after a design basis event. The requirement to impose condition is capable of performing its safety function monitoring on a subset of Class I E electrical cables implies that under significant environmental stresses qualifications by type testing is no longer adequate. This is inconsistent resulting from design basis accidents in with the qualification philosophy contained within IEEE 323-2003 and its order to avoid common-cause failures.
daughter standards.
This is consistent with IEEE Std 323-2003 The requirement for CM is also being imposed without any condition (and its previous versions).
monitoring techniques being endorsed by IEEE 383-2003. The introduction of cable CM establishes a requirement for testing with no Regulatory Guide 1.89 further states, defined test methodology or acceptance criteria, ...state-of-the-art preconditioning techniques are not capable of simulating The recommended use of such cable CM programs is also inconsistent all significant types of degradation, and with prior NRC conclusions regarding cable condition monitoring. The natural pre-aging is difficult and costly. ....
technical assessment of Generic Safety Issue 168, determined that "typical Experience suggests that consideration I&C cable qualification test programs include numerous conservative should be given, for example, to a April 13, 2009 3
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 practices that collectively provide a high level of confidence that the combination of (1) preconditioning of test installed I&C cables will perform their intended functions during and samples employing the Arrhenius theory following design-basis events, as required by Title 10, Section 50.49, (10 and (2) surveillance, testing, and CFR 50.49), of the Code of Federal Regulations "Environmental maintenance of selected equipment Qualification of Electrical Equipment Important to Safety for Nuclear specifically directed toward detecting Power Plants". those degradation processes that, based on experience, are not amenable to IEEE Recommendation: The requirement for condition monitoring of preconditioning and that could result in Class 1 E cables should be omitted from the "Discussion Regulatory common-cause functional failure of the Positions 2(c) and 10. equipment during design basis accidents.
The industry data received in response to GL 2007-01 indicated over 400 power cable failures. Some of the cables were environmentally qualified. The NRC staff believes these failures can be significantly reduced through a condition-monitoring program.
Therefore, an appropriate condition-monitoring program for cables must be incorporated in a maintenance program in a nuclear power plant. Testing of one prototype in a laboratory and then conducting little or no surveillance for 40 years (or longer) does not provide a reasonable level of confidence in cable performance. Monitoring of environmental conditions and radiation levels and adopting suitable technique(s) for condition monitoring are the necessary steps to provide a reasonable level of confidence.
Power cables that are routed underground April 13, 2009 4
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 should be capable of performing their function when subjected to anticipated environmental conditions such as moisture or flooding. This is consistent with Generic Letter GL 2007-1.
Note that Regulatory Position 10 was revised.
IEEE - PES Regulatory Clause 3.3, "Representative Cable," of IEEE Std 383-2003 should be Regulatory Position 1 was modified to Position 1 supplemented with a description of conductor type (material, strand, and better reflect staff intent.
Clause 3.3 strand type) and also differentiate between conductor shield, insulation shield, and overall static shield. Documenting the details of the sample tested is essential to determine if any IEEE Comment, The IEEE is not aware of any research, qualification test, future analysis is needed.
or experience information suggesting that conductor material, strand, and strand type can affect qualification results of the cables performance during DBE testing. Since this change is being recommended to the definition of "representative cable" this could lead to the interpretation that any change in the conductor material, strand, and strand type would have to be qualified. The requirement to include additional test samples for a change that does not impact qualification is not warranted and will add an unnecessary complexity to the qualification process.
IEEE Recommendation: Delete regulatory position 1.
IEEE - PES Regulatory Clause 4, "Principal Qualification Criteria," should be supplemented as Regulatory Position 2(a) and 2(b) were Position 2 follows: deleted.
Clause 4 (a) the documentation should include the cable or field splice's specification and qualification plan. Regulatory Position 2(c) on condition (b) the documentation should include manufacturer's inspection and monitoring was deleted because this maintenance requirements to maintain and demonstrate continued concept was covered in Regulatory qualification throughout its qualified life. Position 10 in DG-1132.
(c) a condition monitoring program should also be implemented.
IEEE Comment: The information required with items (a) and (b) is April 13, 2009 5
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 currently required. Clause 4 currently requires that the documentation used to demonstrate qualification includes:
- The cable or field splices specification or qualification plan.
- Inspection and maintenance requirements.
- Summaries and conclusions.
See previous comments on cable condition monitoring.
IEEE Recommendation: Delete Regulatory Position 2.
IEEE - PES Regulatory Clause 6.1.2, "Coaxial, triaxiel, and twinaxial," should also include Regulatory Position 3 was deleted Position 3 specimens of identical materials and construction, and configuration Clause 6.1.2 should include connections.
IEEE comments: Clause 6.1.2 currently requires that test specimens use identical materials and unique construction features, including braid angle and shield filler materials. The test specimens must also meet the requirements of a "Representative Cable". To add identical constructions could be implied to mean that every coaxial cable (RG 6, 58, etc.) is tested. This will require test specimens for each and every cable variation offered by a manufacturer. Such a requirement is an unnecessary burden, inhibits the use of minor cable design changes, and is inconsistent with the qualification of other cable types. IEEE 383-2003 and current practice rely on testing of representative cables with identical materials and specific characteristics but do not require identical constructions.
IEEE also disagrees that the coaxial, triaxial, and twinaxial test specimens include connections. IEEE 383-2003 specifically removed connections from its scope. Connectors are now addressed in IEEE Std. 572. The requirement to test cable and connectors could also be Interpreted as qualifying a "matched set". This could further lead to the Interpretation that every variation of cable and connector must be type tested. It should also be noted that IEEE 383-2003 now requires that coaxial, triaxial, and twinaxial cable be tested with their jacket to ensure that Jacket integrity Is maintained. This is intended to ensure that jacket integrity is maintained April 13, 2009 6
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 for qualified connectors and splices that rely on said performance.
IEEE recommendation: Delete Regulatory Position 3.
IEEE - PES Regulatory Clause 6.3, "Age-conditioning" should be supplemented to include aged Regulatory Position 7 was deleted.
Position 7 cable specimen and new splice kits; and a new splice kit combining an Clause 6.3 aged cable with a new cable.
IEEE comment: It Is believed that the requirement to combine In a new cable splice with an aged cable is intended to demonstrate that the aged cable will not adversely affect the splice. This test configuration is not considered relevant to future qualification tests performed in accordance with IEEE 383-2003. IEEE 383-2003 requires that a 20 X diameter mandrel bend test be performed after normal environment thermal and radiation aging. This test demonstrates the cable jacketing material will retain some flexibility at the end of its qualified life. This effectively precludes Installing splices onto embrittled cables within their specified qualified life. IEEE 383-1974 did not require this test if a similar 40 X diameter mandrel bend test was performed after the accident exposure.
The requirement for the mandrel bend test after thermal and radiation aging is an enhancement to the qualification type test defined in IEEE 383-2003.
IEEE Recommendation: Delete Regulatory Position 7.
IEEE - PES Regulatory Clause 6.4.5, "Retained Flexibility," should be supplemented to include Regulatory Position 8 was deleted.
Position 8 the following:
Clause 8.4.5 "The acceptance criteria for Instrument cables should specify the See revised Regulatory Position 5.
minimum acceptable insulation resistance and signal attenuation limits".
IEEE Comment: The mandrel bend tests are intended to test the Integrity of the cable not establish a suitable level of electrical performance for specific instruments. The acceptable performance of an Instrument cable during a OBE Is an installation specific evaluation which is dependent on device type and cannot be determined by the cable manufacturer or the test lab.
April 13, 2009 7
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 IEEE Recommendation: Delete Regulatory Position 8.
NUGEQ Regulatory Regulatory Position (1) - Clause 3.3, "Representative Cable, of IEEE Std Regulatory Position 1 was modified.
Position 1 383-2003 should be supplemented with a description of conductor type Clause 3.3 ('material, strand, and strand type) and also differentiate between The supplemental information is for conductor shield, insulation shield, and overall static shield. descriptive purposes and should be documented for any future analysis if NUGEQ Comment: Regulatory Position 1 (RP1) is unclear since it does needed.
not indicate if the recommended supplemental information is simply for descriptive purposes or if the NRC expects the Representative Cables to contain the same conductor and shield materials and configurations that are being qualified. Clause 3.3 currently specifies the characteristics of qualified cable styles than must be included in the qualification test program's Representative Cables. Among other characteristics it currently requires that the Representative Cables contain (a) the same shield materials as the cable styles being qualified and (b) construction/configuration features that conservatively represent the cable style features. It does not require the same conductor materials or types.
If the additional information specified by RP1 is intended to more fully describe the cable test specimens (i.e., representative cables) then RP1, instead of referencing Clause 3.3 should reference Clause 6.2 "Description of cables and field splices", particularly 6.2.1.1 "Conductor" and 6.2.1.4 "Shielding." In this case RP1 may not be necessary since 6.2.1.1 currently specifies "Material type identification, size, stranding, and coating", and 6.2.1.4 specifies, "Material identification, thickness, and form, including the braid angle for braided shields."
If instead the NRC expects that the Representative Cables contain the same conductor materials and configurations being qualified then the NUGEQ disagrees with RP1. The regulatory position is unnecessarily restrictive and could be interpreted to require qualification testing of each and every conductor/shield configuration. The standard correctly requires that Representative Cables contain the same materials and correctly permits conductor and shield configuration variations (e.g., type of April 13, 2009 8
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 stranding) when justified. The NUGEQ is not aware of any research, qualification test, or experience information suggesting that conductor material, strand, and strand type can affect qualification results for the cable's insulation system. Regarding medium voltage conductor and insulation shields (i.e., semicon layers), Clause 3.3 requires the same shield materials and construction/configuration features to be included in the Representative Cable. The Clause 3.3 language similarly requires that the Representative Cables must include the same overall shield materials (e.g., aluminum-mylar, braided, or copper tape). These provisions are both sufficient and permit needed flexibility.
NUGEQ Recommendation: Delete RPI. RP1 is unnecessary if the requested information is for descriptive purposes since Clause 6.2 requires such information. Instead, if RP1 specifies needed characteristics of Representative Cable then it erroneously identifies conductor characteristics and appears redundant to existing Clause 3.3 language regarding shields.
NUGEQ Regulatory Regulatory Position (2) - Clause 4, "Principal qualification criteria," Regulatory Positions 2(a) and 2(b) were Position 2 should be supplemented as follows: deleted.
Clause 4. (a) The documentation should include the cable or field splice's specification and qualification plan. Regulatory Position 2(c) on condition (b) The documentation should include manufacturer's inspection and monitoring also was deleted because maintenance requirements to maintain and demonstrate continued Regulatory Position 10 covers this qualification throughout its qualified life. concept.
(c) A condition monitoring program should also be implemented.
See revised Regulatory Position 6.
NUGEQ Comment: RP2 (a) and (b) appear unnecessary because Clause 4 (paragraph 4) currently requires that the documentation used to demonstrate qualification includes:
- The cable or field splice's specification or qualification plan
- The documents that demonstrate compliance with the qualification plan
- Inspection and maintenance requirements
- Summaries and conclusions" April 13, 2009 9
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 See NUGEQ Comment 10 regarding condition monitoring and RP2(c).
NUGEQ Recommendation: Delete RP 2. Delete RP 2(a) and 2(b) since they are redundant to existing Clause 4 language. See NUGEQ Comment 10 regarding condition monitoring and delete RP 2(c).
NUGEQ Regulatory Regulatory Position (3) - Clause 6.1.2, Coaxial, triaxial, and twinaxial, Regulatory Position 3 was deleted.
Position 3 should also include specimens of identical materials and construction, and Clause 6.1.2 the configuration should include connections.
NUGEQ Comment: Clause 6.1.2 current requires coaxial, triaxial, and twinaxial test specimens to use identical materials and unique construction features, including braid angle and shield filler materials. The test specimens must also meet the requirements of Clause 3.3 "Representative Cable. However, these provisions do not require "identical construction" or use of connections for cable test specimens.
The NUGEQ disagrees that the coaxial, triaxial, and twinaxial test specimens must be identical in construction to qualified cable types since this requires test specimens for each and every cable variation offered by a manufacturer. Such a requirement is an unnecessary cost burden, inhibits the use of minor cable design changes to meet application unique considerations, and is inconsistent with the qualification of other cable types (e.g., power and multiconductor cables). IEEE 383 2003 and current practice rely on testing of representative cables with identical materials and specific characteristics but do not require identical constructions. For example, a 3 or 5 conductor multiconductor test specimen is considered, with appropriate justification, to be representative of other multiconductor cables with a different number of conductors.
The NUGEQ disagrees that the coaxial, triaxial, and twinaxial test specimens must include connections. As noted in the IEEE 383 2003 Introduction, connections were removed from the title and scope because IEEE Std 572 is specific to the qualification of connections. Importantly, IEEE 383-2003 Clause 6.1.2 requires that coaxial, triaxial, and twinaxial cable to be tested with their jackets to establish, among other things, that April 13, 2009 10
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 the jacket maintains "integrity for connector and splice applications requiring such integrity." This is a new provision not contained in the previous version of IEEE 383. Since there can be a wide variety of qualified connector designs used on a particular cable, it is not meaningful to include one style with the cable test specimen. Further, inclusion of a connector as part of the cable test specimen confuses the test data since electrical measurements reflect the electrical characteristics of both the cable and connector.
NUGEQ Recommendation: Delete RP 3 NUGEQ Regulatory Regulatory Position (4) - Clause 6.2.1. 1, "Conductor, should include the Regulatory Position 4 was modified as Position 4 stranding configuration. suggested.
Clause 6.2.1.1 NUGEQ Comment: Clause 6.2.1.1, "Conductor," currently requires (See new Regulatory Position 2).
"Material type identification, size, stranding, and coating." Stranding is typically defined as the number of strands, the wire size of each strand (i.e., a 7/20 12 awg conductor consists of 7 strands of #20 awg wire), and, in some cases, if the stranding is round, compressed, or compact. It is unclear what additional information the NRC is requesting by use of the term "stranding configuration" but the NUGEQ suspects it refers to -
round, compressed, or compact.
NUGEQ Recommendation: Delete RP4 or clarify "stranding configuration" as follows - "stranding configuration (round, compressed, or compact)."
NUGEQ Regulatory Regulatory Position (6) - Clause 6.2.2.6, "Identification," should include Regulatory Position 6 has been clarified as Position 6 the date of applicable manufacturing standards and the date of suggested.
Clause 6.2.2.6 manufacture.
(See new Regulatory Position 3).
NUGEQ Comment: Both 6.2.1.8 (for cables) and 6.2.2.6 (for field splices) require test specimen identification by manufacturer's trade name or The NRC staff is concerned about catalog number. Additional test specimen information, such as the traceability of cable and field splices back manufacturer's applicable fabrication and material specifications and date to the original type tests, potentially years of manufacture, could aid in test specimen traceability but would be after the original manufacturer performed April 13, 2009 11
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 available along with other manufacturing records for specimens fabricated the type tests. Additionally, many of the under appropriate QA controls (10 CFR 50 Appendix B). cables or field splices may only be available as commercial products not NUGEQ Recommendation: Delete RP 6 or for consistency identify both fabricated in accordance with Appendix B Clause 6.2.1.8 (for cables) and 6.2.2.6 (for field splices). of 10 CFR 50.
NUGEQ Regulatory Regulatory Position (7) - Clause 6.3, "Age conditioning, should be Regulatory Position 7 was deleted.
Position 7 supplemented to include aged cable specimen and new splice kits; and a Clause 6.3 new splice kit combining an aged cable with a new cable. However, a cautionary note was added as suggested in the Discussion Section.
NUGEQ Comment: The NUGEQ disagrees with RP7. For cable and field splice qualification for harsh DBE conditions, IEEE 383-2003 (Clauses The cautionary note reads:
6.2.3 and 6.2.4) require at least two test specimens - one unaged and one aged (thermal and radiation). This is consistent with current practice and NRC research suggests the potential for accepted cable and field splice qualification programs. In contrast, RP7 cracking of age-embrittled cable materials specifies the use of two additional specimens, (new splice/aged cable and during subsequent installation of field new splice/aged & new cable), for qualification of field splices. splices.
We assume the NRC may be basing this position on certain testing described in NUREG/CR-6704. Except for that testing the NUGEQ is unaware of any research, qualification, or experience suggesting the need for such "mixed age" field splice specimens. In prior correspondence with the NRC1, the NUGEQ observed that the NUREG problems, which occurred on certain test splices made onto previously aged and accident irradiated cable specimens, were largely due to handling damage to the severely embrittled insulation/jacket materials during splice application.
This test artifact is not relevant to future qualification tests performed in accordance with IEEE 323-2003, in part, because IEEE 323-2003 Clause 6.4.2d requires a 20D mandrel bend after thermal and radiation aging.
This test demonstrates that the cable insulation materials retain some flexibility at the end of their qualified life. This effectively precludes installing splices onto embrittled insulating materials if the cables are within their specified qualified life. The prior (but not the current version) of IEEE 323 did not require this test if a similar 40D mandrel bend test was performed after the accident exposure.
April 13, 2009 12
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 NUGEQ Recommendation: Delete RP7. Alternatively, revise RP7 to caution licensees that NRC research suggests the potential for cracking of age-embrittled cable materials during subsequent installation of field splices.
1 See NUGEQ letter to Satish Aggarwal, Comments on EQ Task Action Plan Research: Invitation to NUGEQ Meeting, (July 8, 1999)
NUGEQ Regulatory Regulatory Position (8) - Clause 6.4.5, "Retained flexibility, " should be Regulatory Position 8 was modified as Position 8 supplemented to include the following: suggested and is included in new Clause 6.4.5 "The acceptance criteria for instrument cables should specify the Regulatory Position 4.
minimum acceptable insulation resistance and signal attenuation limits."
The qualification type tests for coaxial, NUGEQ Comment: Clause 6.4.5 currently identifies tests that are used to triaxial, and twinaxial cables should demonstrate that the cable test samples retain some degree of flexibility include sufficient testing of the cables after the harsh DBE simulation. This is accomplished by immersion high critical electrical performance potential testing of the specimen after a specified mandrel bend. The test characteristics to permit an adequate establishes physical integrity and dielectric capability and is not directly analysis of the compatibility of the coaxial, related to electrical performance criteria such as insulation resistance and triaxial, and twinaxial cables for the signal attenuation limits. These performance criteria have no meaning specific application, as appropriate.
within the context of this mandrel bend testing.
Clause 6.4.4, "Design basis event simulation," currently requires that the acceptance criteria for applications shall be specified. This clause also states that "Performance criteria, such as current, insulation resistance, and impedance, shall be pertinent to the sample construction and application and will differ from power, control, and instrumentation applications, such as the functional role of the jacket in protecting shields in concentric constructions." It also specifies that "Any specialized applications using these cables for their high-frequency capability, for example, must be specifically evaluated to define performance criteria."
Finally, the NUGEQ notes that acceptance criteria for instrument cables will vary based on cable type and application. For example, signal attenuation criteria would not apply to all types of instrument cables.
April 13, 2009 13
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 NUGEQ Recommendation: Delete RP8 because the guidance is not applicable to Clause 6.4.5 and equivalent guidance already exists in Clause 6.4.4. Alternatively, reference Clause 6.4.4 and not Clause 6.4.5 and add the words "as appropriate" after "signal attenuation limits."
NUGEQ Regulatory Regulatory Position (9) - Clause 9.1, "General, "should be supplemented Regulatory Position 9 was modified as Position 9 to include the following: suggested.
Clause 9.1 "Identification of the applicable date of manufacturing standards used in specification, manufacture, and selection of the factory acceptance See new Regulatory Position 3.
criteria for test specimens. Documentation should also include manufacturer's inspection and maintenance requirements."
NUGEQ Comment: The first part of RP9 refers to the date of manufacturer standards associated with test specimen specification, manufacture, and factory acceptance. This position appears to be redundant to RP6 which requests similar information under Clause 6.2.2.6.
The second part of RP9 requests documentation of manufacturer inspection and maintenance requirements. The NUGEQ notes that Clause 4 currently requires that qualification documentation include "Inspection and maintenance requirements" but this requirement was not restated in the general documentation guidance in Clause 9.1.
NUGEQ Recommendation: Consolidate the RP6 and RP9 guidance on test specimen information into RP6 and limit RP9 guidance to Inspection and Maintenance Requirements.
NUGEQ Regulatory Regulatory Position (10) -Power and instrumentation and control cables Regulatory Position 10 was revised (See Position 10 for which failures could disable risk-significant equipment should have new Regulatory Position 6):
condition monitoring programs to demonstrate that the cables can perform their safety functions when needed. Programs for monitoring of environmental conditions (such as temperature, radiation NUGEQ Comment: The NUGEQ agrees that ongoing licensee activities levels), and condition monitoring should related to maintaining cable qualification should focus on cables whose be implemented for power, failures could disable risk-significant equipment. The NUREG [sic] also instrumentation, and control cables (the believes that such activities are most appropriate when selectively applied condition monitoring of safety-related April 13, 2009 14
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 to risk-significant cables with the least margin due to qualification levels, cables may be limited to those cables service conditions, or other application considerations. However, the covered by 10 CFR 50.65, Requirements NUGEQ disagrees that cable condition monitoring (CM) programs should for monitoring the effectiveness of be implemented for these cables. As described below, the RP1 0 maintenance at nuclear power plants.).
recommended use of such cable CM programs is inconsistent with prior Condition monitoring programs may NRC conclusions regarding cable CM. We also believe that the IEEE include any appropriate technique(s),
considered and rejected incorporating guidance on such condition supplemented with walkdowns to look for monitoring during the development of IEEE 383-2004. visible signs of anomalies attributable to aging with particular emphasis on the An August 14, 2003 NRC memorandum
Subject:
Closeout of Generic identification of localized adverse Safety Issue (GSI) 168, "Environmental Qualification of Low-Voltage environments or hot spots. For safety-Instrumentation and Control Cables" documented the resolution of related power cables that are inaccessible Generic Safety Issue 168, "Environmental Qualification of Low-Voltage or installed underground, appropriate Instrumentation and Control (I&C) Cables. "The memorandum states: inspection, testing and monitoring "The issue was resolved with no new requirements for licensees." The programs should be implemented to detect memorandum makes no recommendations regarding the use of cable CM degradation. The condition monitoring including the specific CM methods evaluated as part of the GSI-168 and its frequency may be adjusted based efforts. on the cable performance.
The memorandum states, based on the GSI technical assessment, that The NRC staff has found installed cables "typical I& C cable qualification test programs include numerous that were operating outside their assumed conservative practices that collectively provide a high level of confidence environmental operating parameters and that the installed /&C cables will perform their intended functions during may not have performed their safety-and following design-basis events, as required by Title 10, Section 50.49, related function(s). The number of failures (10 CFR 50.49), of the Code of Federal Regulations "Environmental recorded in response to GL-2007-01 Qualification (EQ) of Electric Equipment Important to Safety for Nuclear further supports the need for a cable-Power Plants." The memorandum also concludes that in order to maintain monitoring program.
qualification margin and conservatism, "licensee walkdowns to look for any visible signs of anomalies attributable to aging with particular emphasis on the identification of localized adverse environments or "hot spots, coupled with the knowledge of the operating service environments, have proven to be effective and useful in ensuring that qualification is maintained."
The staff also issued RIS 2003-09 "Environmental Qualification of Low-April 13, 2009 15
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 Voltage Instrumentation and Control Cables, (May 2, 2003) to disseminate results from the GSI-168 efforts. The RIS observations are more detailed but consistent with the GSI-168 closeout memorandum.
Regarding cable CM the RIS states: "The staff has concluded that, although a single reliable condition-monitoring technique does not currently exist, walkdowns to look for any visible signs of anomalies attributable to cable aging, coupled with monitoring of operating environments, have proven to be effective and useful."
Regarding typical licensee activities the RIS notes: "When unexpected localized adverse conditions are identified, the condition of the affected cables is evaluated and appropriate corrective action is taken. Monitoring or inspection of environmental conditions or component parameters was generally conducted to ensure that the component is within the bounds of its qualification basis."
Regarding risk assessments and cable aging the RIS states: "One of the key assumptions of the risk assessment is that operating environments are less severe than or the same as those assumed during qualification testing.
These assumptions can be relied upon provided licensees have ongoing knowledge of environmental operating conditions at the nuclear power plants."
IEEE 383-2003 specifies cable qualification methods (test, operating experience, and analysis) with an emphasis on qualification by test. The standard does not identify the need for ongoing licensee activities (e.g.,
condition monitoring) in order to maintain the qualified status of cables qualified by these methods. Of course, this assumes that the cables are operated within the service limits (i.e., environmental and operational limits) established by that qualification. We understand that condition monitoring was considered by the IEEE during development of IEEE 383-2002 and was not incorporated into the standard.
NUGEQ Recommendation: Revise RP10 to read as follows:
April 13, 2009 16
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 (10) Knowledge of environmental conditions and cable inspections should be considered for power, instrumentation and control cables whose failures could disable risk-significant equipment to ensure that the cables are within the bounds of their qualification basis. Licensee walkdowns to look for visible signs of anomalies attributable to aging with particular emphasis on the identification of localized adverse environments or "hot spots, coupled with the knowledge of the operating service environments, have proven to be effective and useful in ensuring that qualification is maintained. Such activities are most appropriate when applied to such cables with the least margin due to qualification levels, service conditions, or other application considerations.
Replace Discussion sentence beginning "In addition, power and instrumentation and control cables for which failures could disable . . ."
with the following:
In addition, knowledge of environmental conditions and cable inspections should be considered for power and instrumentation and control cables whose failures could disable risk-significant equipment to ensure that the cables are within the bounds of their qualification basis.
Duke Energy Section B The last paragraph does not specifically address IEEE 383-2003 like the The last paragraph is included because it Discussion rest of that section. Instead, it introduces concerns specific to is a recent concern as discussed in NRC Page 2 underground power cables similar to the scope of GL 2007-01. How does Generic Letter 2007-01, Inaccessible or this information relate to IEEE 383-2003? Since "recent underground Underground Power Cable Failures that power cable failures" are cited (and not splices), what is the basis for Disable Accident Mitigation Systems or "field splices for medium voltage cables in inaccessible locations should Cause Plant Transients, dated February not be permitted? If this paragraph must remain and still with the 7, 2007.
"should" recommendation terminology, the "should not be permitted" could be better worded as "should be avoided." The words should not be permitted have been replaced with should be avoided, as suggested.
uke Energy Section C Item (1) on the definition of "Representative Cable": The qualification and Regulatory Position 1 modified.
Regulatory thus representative cable specimen should not be specific to a particular Position 1 stranding of conductor. If the concern is one of fully describing the April 13, 2009 17
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 representative cable, clause 6.2.1.1 Conductor within IEEE-383-2003 already requires "Material type, identification, size, stranding, and coating." This comment also addresses Page 3 item (4) of DG-1132.
Duke Energy Regulatory Items (2)(c) and (10): The operational scope of the added "condition Regulatory Position 2(c) was deleted. The Position 2(c) monitoring program" implementation recommendation is broader than the concept for condition monitoring is and 10. qualification scope of IEEE-383-2003. If these clauses must remain, then included in Regulatory Position 10.
(2)(c) should be worded consistently by adding "... be implemented for cables whose failures could disable risk-significant equipment."
Duke Energy Regulatory Item (3): Was the recommendation to include "connections" intended to be Regulatory Position 3 was deleted.
Position 3 "field splices" per the scope of IEEE-383-2003? Page 4 of DG-1 132, REGULATORY ANALYSIS, Section 1. Background, last sentence already acknowledges the word "connections" being removed from the title and scope of the standard because IEEE 572-1985 covers qualification of connections.
Duke Energy References Item 1, the "1994" may be a typographical error as it appears inconsistent The commenter is correct and the with the other listed references. It should match up with the "2003" IEEE reference has been corrected.
383 reference or its 2004 copyright and publish year.
Exelon Section B On page 2, in the last paragraph in Section B, "Discussion," the NRC The wording was revised to read:
AmerGen Discussion makes reference to field splices for medium-voltage cables in Last inaccessible locations should not be permitted" Exelon/AmerGen request ...the staff has concluded that the field Paragraph that the NRC provide clarification concerning the intent of this statement. splices for medium-voltage cables in Specifically, is it the NRC's intent to preclude pulling splices into inaccessible locations should be avoided.
inaccessible locations?
Exelon Regulatory On page 3, Section C, "Regulatory Position, Item 10 states: "Power and Regulatory Position 10 was revised.
AmerGen Position 10 instrumentation and control cables for which failures could disable risk-significant equipment should have condition monitoring programs to demonstrate that the cables can perform their safety function when needed. Exelon/AmerGen believe that this issue warrants further discussion and request that additional clarification be provided in the following areas:
In response to comment A. -
A. The scope of DG-1132 is primarily for Class 1 E cables located in The words, Risk-significant were harsh environments. "Risk-significant" equipment is not necessarily deleted.
defined in scope of DG-1 132, and therefore, Exelon/AmerGen April 13, 2009 18
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 recommend clearly defining the scope of the guidance provided in DG-1132.
In response to comment B. -
B. Generic Letter (GL) 2007-01, "Inaccessible or Underground Power The bases for an establishment of Cable Failures that Disable Accident Mitigation Systems or Cause condition monitoring program are 10 CFR Plant Transients," recommends that licensees should have power cable Appendix A, criterion 18; 10 CFR 50.65 condition monitoring programs for Maintenance Rule systems. The and 10 CFR 50.49; and lessons learned GL does not specifically mandate cable condition monitoring from operating experience over the past 30 programs, and the regulatory basis for requiring a cable condition years.
monitoring program is not established or clearly defined in any NRC documentation. Therefore, Exelon/AmerGen request further clarification concerning the basis for requiring a cable condition monitoring program.
C. DG-1132 discusses that the need for equipment qualification is to In response to comment C. -
prevent common mode failure due to harsh environments resulting The scope for condition monitoring of from a Design Basis Earthquake (DBE). As such, any cable condition cables is limited to those covered by the monitoring program would be limited to those cables whose Maintenance Rule.
qualification aging conditions were not consistent with actual installed plant conditions. Exelon/AmerGen would not expect to find too many Class 1 E cables, which would be subject to a post DBE environment, to be in any environment not enveloped by the qualification plan. One possible exception would be if a Class l-E harsh environment cable was continuously immersed in water; this probably would not be considered a qualification aging technique. Therefore, Exelon/AmerGen request further clarification concerning this issue.
D. DG-1 132 explains that the need for equipment qualification is to In response to comment D. -
prevent common mode failure due to harsh environments resulting An inspection of the entire length of the from a DBE. Section C, "Regulatory Position," Item 10 does not limit cable and verification that the total length the scope of cable condition monitoring to cables in harsh has been enveloped within design environments. There is no identified common cause, other than the assumptions (due to changing harsh environment, that would cause multiple cables to fail. Therefore, environmental conditions or Exelon/AmerGen request further clarification concerning this issue. misapplication) may not be practical. A monitoring program at suitable intervals April 13, 2009 19
Comments Resolution of Public Comments Section of Originator Specific Comment NRC Resolution DG-1132 E. DG-1 132 does not appear to include a discussion about Regulatory ensures functional integrity of the cable.
Position Item 10 in the Regulatory Analysis section of the draft Regulatory Guide. The Conclusion section indicates that the proposed In response to comment E. -
action will reduce unnecessary burden. Imposing cable condition The reduction in burden was addressing monitoring programs could have a significant impact on licensees with the overall benefit of the regulatory guide.
no clear benefit. Therefore, Exelon/AmerGen request further explanation and clarification regarding the perceived benefit.
F. Exelon/AmerGen does not believe that there is an assured means of In response to comment F. -
monitoring cables to determine if they can perform their intended In certain cases, use of more than one safety function. Comments were provided to the NRC on the draft GL technique may be needed to assess the 2007-01 relative to this specific issue. The industry attempted to degradation of the cable insulation. In portray that cable condition monitoring technology is not capable of addition to the techniques mentioned in the determining the remaining life in a cable. HiPot testing will fault comment, the use of Line Resonance cables that have pre-existing conditions; however, many view this Analysis based on frequency domain destructive testing methodology as overly stressful on cables. This reflectometry for monitoring the insulation testing can potentially cause failures in cables that have considerable is gaining wider acceptance for a variety of life remaining. Other non-destructive testing methodologies, such as cable types.
Partial Discharge (PD) and Polarization Index (Tan-Delta), can provide advance indications of changes in the cable's characteristics, The purpose of the monitoring program is but there is not enough library information on these tests to provide to observe the rate of insulation acceptance criteria. IEEE 400, "Guide for Field Testing and degradation and to reduce the cable Evaluation of the Insulation of Shielded Power Cable Systems," does failures during the performance of a safety provide criteria for PD tests on XLPE insulated cables; however, EPR function.
insulated cables are predominant in the nuclear industry. EPR cables do not trend linearly to failure; they tend to test well, and then cascade to failure over a period of a few months. Therefore, Exelon/AmerGen request that the NRC provide additional explanation and clarification concerning the basis for cable condition monitoring.
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