2191 R0 XI.E2

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XI.E2 ELECTRICAL INSULATION FOR ELECTRICAL CABLES AND CONNECTIONS NOT SUBJECT TO 10 CFR 50.49 ENVIRONMENTAL QUALIFICATION REQUIREMENTS USED IN INSTRUMENTATION CIRCUITS

Program Description

The purpose of this aging management program (AMP) is to provide reasonable assurance that the intended functions of electrical cables and connections (that are not subject to the environmental qualification requirements of Title 10 of the Code of Federal Regulations (10 CFR) 50.49 and are used in instrumentation circuits with sensitive, high voltage, low-level current signals) are maintained consistent with the current licensing basis through the subsequent period of extended operation.

In most areas within a nuclear power plant the actual operating environment (e.g., temperature, radiation, or moisture) is less severe than the plant design bases environment. However, in a limited number of localized areas, the actual environment may be more severe than the plant design bases environment. These localized areas are characterized as “adverse localized environments” that represent a limited plant area where the operating environment is significantly more severe than the plant design basis environment. An adverse localized environment exceeds the most limiting environment (e.g., temperature, radiation, or moisture) for the cable or connection insulation. A discussion of adverse localized environments and methods of identifying them can be found in Generic Aging Lessons Learned for Subsequent License Renewal (GALL-SLR) Report AMP XI.E1.

Exposure of electrical insulation to adverse localized environments caused by temperature, radiation, or moisture can cause age degradation resulting in reduced electrical insulation resistance, moisture intrusion related connection failures, or errors induced by thermal transients. Reduced electrical insulation resistance causes an increase in leakage currents between conductors and from individual conductors to ground. A reduction in electrical insulation resistance is a concern for all circuits, but especially those with sensitive, high-voltage, low-level current signals, such as radiation monitoring and nuclear instrumentation circuits, because a reduced insulation resistance may contribute to signal inaccuracies.

In this AMP, in addition to the evaluation and identification of adverse localized environments, either of two methods can be used to identify the existence of electrical insulation aging effects for cables and connections. In the first method, calibration results or findings of surveillance testing programs are evaluated to identify the existence of electrical cable and connection insulation aging degradation. In the second method, direct testing of the cable system is performed.

This AMP applies to high-range-radiation and neutron flux monitoring instrumentation cables in addition to other cables used in high-voltage, low-level current signal applications that are sensitive to reduction in electrical insulation resistance. For these cables, GALL-SLR Report AMP XI.E1 does not apply.

As stated in NUREG/CR–5643, “the major concern is that failures of deteriorated cables might be induced during accident conditions.” Since the cable and connection electrical insulation is not subject to the environmental qualification requirements of 10 CFR 50.49, an AMP is needed to manage the aging mechanisms and effects for the subsequent period of extended operation. This AMP provides reasonable assurance that the electrical insulation for electrical cables and connections will perform its intended function for the subsequent period of extended operation.

Evaluation and Technical Basis

1. Scope of Program: This AMP applies to electrical cables and connections (cable system) electrical insulation used in circuits with sensitive, high-voltage, low-level current signals. Examples of these circuits include radiation monitoring and nuclear instrumentation that are subject to aging management review and subjected to adverse localized environments caused by temperature, radiation, or moisture.

2. Preventive Actions: This is a performance monitoring program and no actions are taken as part of this program to prevent or mitigate aging degradation.

3. Parameters Monitored or Inspected: The parameters monitored are determined from the specific calibration, surveillances, or testing performed and are based on the specific instrumentation circuit under surveillance or calibration, as documented in plant procedures.

4. Detection of Aging Effects: Review of calibration results or findings of surveillance programs can provide an indication of the existence of aging effects based on acceptance criteria related to instrumentation circuit performance. By reviewing the results obtained during normal calibration or surveillance, an applicant may detect severe aging degradation prior to the loss of the cable and connection intended function. The first reviews are completed prior to the subsequent period of extended operation and at least every 10 years thereafter. Calibration or surveillance results that do not meet acceptance criteria are reviewed for aging effects when the results are available.

Cable system testing is conducted when the calibration or surveillance program does not include the cabling system in the testing circuit, or as an alternative to the review of calibration results described above. A cable system test for detecting deterioration of the electrical insulation system is performed. This can be one or more of the following tests: insulation resistance tests, time domain reflectometry tests, or other testing judged to be effective in determining cable system insulation physical, mechanical, and chemical properties, as applicable. The test frequency of the cable system is determined by the applicant based on engineering evaluation, but the test frequency is at least once every 10 years. The first test is to be completed prior to the subsequent period of extended operation.

5. Monitoring and Trending: Trending actions are not included as part of this AMP, because the ability to trend visual inspection and test results is dependent on the test or visual inspection program selected. However, inspection and test results that are trendable provide additional information on the rate of cable or connection degradation.

6. Acceptance Criteria: An unacceptable indication is defined as a noted condition or situation, if left unmanaged, could potentially lead to a loss of intended function. Calibration results or findings of surveillance and cable system testing are to be within the acceptance criteria, as set out in the applicant’s procedures.

7. Corrective Actions: Results that do not meet the acceptance criteria are addressed in the applicant’s corrective action program under those specific portions of the quality assurance (QA) program that are used to meet Criterion XVI, “Corrective Action,” of 10 CFR 50, Appendix B. Appendix A of the Generic Aging Lessons Learned for Subsequent License Renewal (GALL-SLR) Report describes how an applicant may apply its 10 CFR 50, Appendix B, QA program to fulfill the corrective actions element of this AMP for both safety-related and nonsafety-related structures and components (SCs) within the scope of this program.

Corrective actions, such as recalibration and circuit trouble-shooting, are implemented when calibration, surveillance, or cable system test results do not meet the acceptance criteria. An engineering evaluation is performed when the acceptance criteria are not met. Such an evaluation is to consider the significance of the calibration, surveillance, or cable system test results and whether the review of calibration and surveillance results or the cable system testing frequency needs to be increased.

8. Confirmation Process: The confirmation process is addressed through those specific portions of the QA program that are used to meet Criterion XVI, “Corrective Action,” of 10 CFR 50, Appendix B. Appendix A of the GALL-SLR Report describes how an applicant may apply its 10 CFR 50, Appendix B, QA program to fulfill the confirmation process element of this AMP for both safety-related and nonsafety-related SCs within the scope of this program.

9. Administrative Controls: Administrative controls are addressed through the QA program that is used to meet the requirements of 10 CFR 50, Appendix B, associated with managing the effects of aging. Appendix A of the GALL-SLR Report describes how an applicant may apply its 10 CFR 50, Appendix B, QA program to fulfill the administrative controls element of this AMP for both safety-related and nonsafety-related SCs within the scope of this program.

10. Operating Experience: Operating experience has identified that a change in temperature across a high range radiation monitor cable in containment resulted in a substantial change in the reading of the monitor. Changes in instrument calibration can be caused by degradation of the circuit cable or connection electrical insulation and represents a possible indication of electrical cable degradation.

The program is informed and enhanced when necessary through the systematic and ongoing review of both plant-specific and industry operating experience including research and development such that the effectiveness of the AMP is evaluated consistent with the discussion in Appendix B of the GALL-SLR Report.

References

10 CFR Part 50, Appendix B, “Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants.” Washington, DC: U.S. Nuclear Regulatory Commission. 2016.

EPRI. EPRI TR–109619, “Guideline for the Management of Adverse Localized Equipment Environments.” Palo Alto, California: Electric Power Research Institute. June 1999.

_____. EPRI TR–110379, “High Range Radiation Monitor Cable Study: Phase 1.” Palo Alto, California: Electric Power Research Institute. November 1998.

_____. EPRI TR–112582, “High Range Radiation Monitor Cable Study: Phase 2.” Palo Alto, California: Electric Power Research Institute. May 2000.

IEEE. IEEE Standard 1205-2014, “IEEE Guide for Assessing, Monitoring and Mitigating Aging Effects on Electrical Equipment Used in Nuclear Power Generating Stations and Other Nuclear Facilities.” New York, New York: Institute of Electrical and Electronics Engineers. 2014.

US NRC. Information Notice 93-33: “Potential Deficiency of Certain Class IE Instrumentation and Control Cables.” Agencywide Documents Access and Management System (ADAMS) Accession No. ML031070494. Washington, DC: U.S. Nuclear Regulatory Commission. April 28, 1993.

_____. Information Notice 97-45, “Environmental Qualification Deficiency for Cables and Containment Penetration Pigtails.” ADAMS Accession No. ML031050410. Washington, DC: U.S. Nuclear Regulatory Commission. July 2, 1997.

_____. Information Notice 97-45, “Environmental Qualification Deficiency for Cables and Containment Penetration Pigtails.” Supplement 1. ADAMS Accession No. ML031050005. Washington, DC: U.S. Nuclear Regulatory Commission. February 17, 1998.

_____. NUREG/CR–5461, “Aging of Cables, Connections, and Electrical Penetrations Assemblies Used In Nuclear Power Plants.” ADAMS Accession No. ML041280192. Washington, DC: U.S. Nuclear Regulatory Commission. July 31, 1990.

_____. NUREG/CR–5643, “Insights Gained From Aging Research.” ADAMS Accession No. ML041530264. Washington, DC: U.S. Nuclear Regulatory Commission. March 31, 1992.

_____. NUREG/CR–5772, “Aging, Condition Monitoring and Loss-of-Coolant Accident (LOCA) Tests of Class IE Electrical Cables Vol. 1 and 2.” ADAMS Accession Nos. ML041270231, ML041280265. Washington, DC: U.S. Nuclear Regulatory Commission. August 31, 1992, November 30, 1992.

_____. Regulatory Guide 1.218, “Condition Monitoring Techniques for Electric Cables Used in Nuclear Power Plants.” ADAMS Accession No. ML103510458. Washington, DC: U.S. Nuclear Regulatory Commission. April 30, 2012.

SNL. SAND96-0344, “Aging Management Guideline for Commercial Nuclear Power Plants-Electrical Cable and Terminations.” Albuquerque, New Mexico: Sandia National Laboratories. September 1996.

Aging Management Program

US NRC regulatory guide

Quality Assurance

Electric Power Research Institute

United States of America

Nuclear Regulatory Commission - The US federal government agency that regulates nuclear power plants

Agency wide Documents Access and Management System - The official recordkeeping system, through which the U.S. Nuclear Regulatory Commission (US NRC) provides access to the "libraries" or collections of publicly available documents

Loss of Coolant Accident