Regulatory Guide 1.211
| ML082530205 | |
| Person / Time | |
|---|---|
| Issue date: | 04/01/2009 |
| 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: ML082530205 (5) | |
U.S. NUCLEAR REGULATORY COMMISSION April 2009 REGULATORY GUIDE
OFFICE OF NUCLEAR REGULATORY RESEARCH
REGULATORY GUIDE 1.211 (Draft was issued as DG-1132, dated June 2007)
QUALIFICATION OF SAFETY-RELATED CABLES
AND FIELD SPLICES FOR NUCLEAR POWER PLANTS
A. INTRODUCTION
This guide describes a method that the staff of the U.S. Nuclear Regulatory Commission (NRC)
considers acceptable for complying with the Commissions regulations for the qualification of safety- related cables and field splices for nuclear power plants.
The regulations established by the NRC in Title 10, Part 50, Domestic Licensing of Production and Utilization Facilities, of the Code of Federal Regulations (10 CFR Part 50) (Ref. 1) require that structures, systems, and components that are important to safety in a nuclear power plant must be designed to accommodate the effects of environmental conditions (i.e., remain functional under postulated design-basis events (DBEs)). Toward that end, General Design Criterion (GDC) 1, Quality Standards and Records, GDC 2, Design Bases for Protection Against Natural Phenomena, GDC 4, Environmental and Dynamic Effects Design Bases, and GDC 23, Protection System Failure Modes, of Appendix A, General Design Criteria for Nuclear Power Plants, to 10 CFR Part 50 contain the general requirements. Augmenting those general requirements, the specific requirements pertaining to the qualification of certain electrical equipment important to safety are contained in 10 CFR 50.49, Environmental Qualification of Electric Equipment Important to Safety for Nuclear Power Plants. In addition, Criterion III, Design Control, of Appendix B, Quality Assurance Criteria for Nuclear Power Plants, to 10 CFR Part 50 requires that, when a test program is used to verify the adequacy of a specific design feature, the test program must include suitable qualification testing of a prototype unit under the most severe DBE.
This regulatory guide contains information collection requirements covered by 10 CFR Part 50
that the Office of Management and Budget (OMB) approved under OMB control number 3150-0011.
The NRC issues regulatory guides to describe and make available to the public methods that the NRC staff considers acceptable for use in implementing specific parts of the agencys regulations, techniques that the staff uses in evaluating specific problems or postulated accidents, and data that the staff needs in reviewing applications for permits and licenses. Regulatory guides are not substitutes for regulations, and compliance with them is not required. Methods and solutions that differ from those set forth in regulatory guides will be deemed acceptable if they provide a basis for the findings required for the issuance or continuance of a permit or license by the Commission.
This guide was issued after consideration of comments received from the public.
Regulatory guides are issued in 10 broad divisions: 1, Power Reactors; 2, Research and Test Reactors; 3, Fuels and Materials Facilities; 4, Environmental and Siting; 5, Materials and Plant Protection; 6, Products; 7, Transportation; 8, Occupational Health;
9, Antitrust and Financial Review; and 10, General.
Electronic copies of this guide and other recently issued guides are available through the NRCs public Web site under the Regulatory Guides document collection of the NRCs Electronic Reading Room at http://www.nrc.gov/reading-rm/doc- collections/reg-guides/ and through the NRCs Agencywide Documents Access and Management System (ADAMS) at http://www.nrc.gov/reading-rm/adams.html, under Accession No. ML082530205.
The NRC may neither conduct nor sponsor, and a person is not required to respond to, an information collection request or requirement unless the requesting document displays a currently valid OMB control number.
B. DISCUSSION
The Institute of Electrical and Electronics Engineers, Inc. (IEEE) Standard 383-2003, IEEE
Standard for Qualifying Class 1E Electric Cables and Field Splices for Nuclear Power Generating Stations, was published June 10, 2004 (Ref. 2). The standard was developed by the Working group on Cables (Subcommittee (SC 2.4)) of the Nuclear Power Engineering Committee of the IEEE and was approved by the IEEE Standards Association on December 12, 2003 (Reaffirmed in 2008). It provides general requirements, direction, and methods for qualifying safety-related cables, field splices, factory splices, and factory rework for service in nuclear power plants. Categories of cables covered include those used for power, control, and instrumentation services, including signal and communication cables.
Most importantly, IEEE Standard 383-2003 requires that the safety-related cables and field splices must meet or exceed specified performance requirements throughout their installed life and be subjected to a quality assurance program that includes design, qualification, and production quality control.
The objectives of equipment qualification are to ensure that safety-related cables (single, multiconductor, and multiplex, as well as coaxial, triaxial, and twinaxial) and field splices can be demonstrated to perform their safety functions under postulated DBEs, and that no failure mechanism exists that could lead to common-cause failures under postulated service conditions. It is the degradation over time, followed by exposure to the environmental extremes of temperature, pressure, humidity, radiation, mechanical stress, or chemical spray (or a combination thereof) resulting from DBEs, that presents a potential for common-cause failures of safety-related cables and field splices. As a result, it is necessary to establish a qualified life for cables and splices that are installed in harsh environments and must perform a safety function during and following a DBE.
These objectives should be accomplished using qualification methods (type testing, operating experience, analysis as a supplement to type testing and operating experience, ongoing qualification, or any combination thereof). However, qualification by analysis alone is not acceptable. Type testing of sample cables or field splices is the preferred qualification method. In addition, IEEE Standard 383-2003 requires documentation, in an auditable form, to demonstrate that cables and field splices are capable of adequately performing their safety functions during and following a DBE.
In Clause 3.3 of IEEE Std 383-2003, an exact description of the representative cable is required to ensure that sufficient information is available for the representative cable to allow future engineering extrapolation of the conclusions from the results of the type tested cable to other cables reported to be represented by the type test.
Different specialty cables (coaxial, triaxial, and twinaxial) have different critical characteristics based on the application such as noise rejection or signal propagation. It is imperative, if an engineering analysis is used to justify an application of one specialty cable based on qualification of a different type of specialty cable, that the critical characteristics be identified in both applications and compared to the qualification type test results. Further, Clause 6.1.2 of IEEE Std 383-2003, requires that suitable test specimen lengths and configuration be included in the DBE test to evaluate the potential for conductor shorting or loss of critical dielectric characteristics due to differential shrinkage or expansion in coaxial and triaxial cables. The NRC staff has witnessed cables which have passed a qualification type test without connectors only to fail the test when the connectors were attached. The failure was traced to RG 1.211, Page 2
unequal thermal expansion of the different cable components fixed at both ends of the cable with connectors.
NRC research suggests the potential for cracking of age-embrittled cable materials during subsequent installation of field splices. Field splices of age-embrittled cables should be avoided.
Power cables that are routed underground should be capable of performing their function when subjected to anticipated environmental conditions such as moisture or flooding. Also, based on recent underground power cable failures, the staff has concluded that field splices of medium-voltage cables in inaccessible locations should be avoided
C. REGULATORY POSITION
The NRC staff considers conformance with the requirements of IEEE Standard 383-2003 an acceptable method for use in satisfying the Commissions regulations with respect to the qualification of safety-related cables and field splices, subject to the following exceptions:
(1) Clause 6.2.1.4, Shielding, of IEEE Std. 383-2003 should be supplemented to include:
(a) information on other shields such as insulation or overall static shield, and (b) percent overlap and lay for tape shields.
(2) Clause 6.2.1.1, Conductor, should include the stranding configuration (i.e., round, compressed or compact).
(3) Clauses 6.2.1.8 and 6.2.2.6, Identification, should include the date of applicable manufacturing standards and the date of manufacture.
(4) Clause 6.4.4 (b) should be supplemented with the following:
The qualification type tests for coaxial, triaxial and twinaxial cables should include sufficient testing of cables critical electrical performance characteristics to permit an adequate analysis of the compatibility of the coaxial, triaxial and twinaxial cables for the specific application, as appropriate.
(5) Clause 9.1, General, should be supplemented to include the following:
Documentation should also include manufacturers inspection and maintenance requirements.
(6) Programs for monitoring of environmental conditions (such as temperature, radiation levels), and condition monitoring should be implemented for safety-related power, instrumentation, and control cables. Condition monitoring programs may include any appropriate technique(s),
supplemented with walkdowns to look for visible signs of anomalies attributable to aging with particular emphasis on the identification of localized adverse environments or hot spots. For safety-related power cables that are inaccessible or installed underground, appropriate inspection, testing and monitoring programs should be implemented to detect degradation. The condition monitoring and its frequency may be adjusted based on the cable performance.
IEEE Standard 383-2003 references several industry codes and standards. If a referenced code or standard has been separately incorporated into the regulations, licensees and applicants must comply with RG 1.211, Page 3
the standard as set forth in the regulations. By contrast, if the NRC staff has endorsed a referenced standard in a regulatory guide, that standard constitutes an acceptable method of meeting a regulatory requirement as described in the regulatory guide.
D. IMPLEMENTATION
The purpose of this section is to provide information to applicants and licensees regarding the NRCs plans for using this regulatory guide. The NRC does not intend or approve any imposition or backfit in connection with its issuance In some cases, applicants or licensees may propose or use a previously established acceptable alternative method for complying with specified portions of the NRCs regulations. Otherwise, the methods described in this guide will be used in evaluating compliance with the applicable regulations for license applications, license amendment applications, and amendment requests.
RG 1.211, Page 4
REFERENCES
1. 10 CFR Part 50, Domestic Licensing of Production and Utilization Facilities, U.S. Nuclear Regulatory Commission, Washington, DC.1
2. IEEE Standard 383-2003, IEEE Standard for Qualifying Class 1E Electric Cables and Field Splices for Nuclear Power Generating Stations, Institute for Electrical and Electronics Engineers, Piscataway, NJ, Published June 10, 2004.2
1 All publicly available NRC published documents such as Regulations, Regulatory Guides, NUREGs, and Generic Letters listed herein are available electronically through the Electronic Reading room on the NRCs public Web site at: http://www.nrc.gov/reading-rm/doc-collections/. Copies are also available for inspection or copying for a fee from the NRCs Public Document Room (PDR) at 11555 Rockville Pike, Rockville, MD; the mailing address is USNRC PDR, Washington, DC 20555; telephone 301-415-4737 or
(800) 397-4209; fax (301) 415-3548; and e-mail PDR.Resource@nrc.gov.
2 Copyrighted or proprietary documents such as IEEE standards may be available for purchase through the issuing organization.
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