ML20214W797

Forwards Draft Safety Evaluation on Equipment Qualification. NRC Intends to Incorporate Evaluation Into SER on Vol 2 of Nuclear Performance Plan.Util Should Respond to Confirmatory Items within 4 Wks

ML20214W797
Person / Time
Site:	Sequoyah
Issue date:	12/05/1986
From:	Youngblood B Office of Nuclear Reactor Regulation
To:	White S TENNESSEE VALLEY AUTHORITY
References
NUDOCS 8612100399
Download: ML20214W797 (13)

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Docket Nos.: 50-327 ~

and 50-328 Mr. S.A. White Manager of Huclear Power Tennessee Valley Authority 5 DEC 1986 6N 38A Lookout Place 1101 Market Street Chattanooga, Tennessee 37402-2801

Subject:

Transmittal of Draft Safety Evaulation on Equipment Qualfication for Sequoyah, Units 1 and 2 ,

Enclosed is a draft copy of the staff evaluation on equipment qualification at Sequoyah, Units 1 and 2. The staff intends to incorporate this evaluation into the Safety Evaluation Report (SER) en Volume 2 of the Nuclear Perfomance Plan which addresses Sequoyah. The purpose of this letter is to transmit the report to the Tennessee Valley Authority (TVA) and to request that TVA respond to the confirmatory items identified in the report.

With the exception of the confimatory items, the staff has found the TVA equipment qualification acceptable. However, TVA should address the issues identified on page 3-10 of the enclosure prior to restart of either Sequoyah unit.

In order for the staff to support the TVA projected restart date for Sequoyah, TVA should respond to the confimatory items within four weeks of the date of this letter. If TVA cannot meet this date, it should provide its proposed date to the staff in writing witliin one week of the date of this letter.

It should be noted that this safety evaluation does not include equipment qualification under superheat conditions. The staff evaluation of that issue was transmitted in my letter dated Novenber 25, 1986.

If you require any additional assistance, please contact the project manager for the Sequoyah SER, Mr. Joseph J. Halonich at (301) 492-7270.

Sincerely, lIk2gDo [ B. J. Youngblood, Director P PWR Project Directorate #4 Division of PWR Licensing-A

Enclosure:

As stated cc: See next page DISTRIBUTION: See next page [

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Mr. S. A. White

. Tennessee Valley Authority '

Secuoyah Nuclear Plant cc:

Tennessee Department of Public Health Regionel Adirinistrator, Region II ATTN: Director, Bureau of U.S. Nuclear Regulatory Cons ission, 101 Marietta Street, N.W. , Suite 2900 Environmental Health Services Atlanta, Georgia 30323 Cordell Hull Buildirg flashville, Tennessee 37219 J. A. Kirkebo ATTN: 0.L. Williams Mr. Michael H. Mobley, Director Tennessee Valley Authority Division of Radiological Health 400 West Sumit Hill Drive, W12 A12 T.E.R.R.A. Building Knoxville, Tennessee 37902 150 9th Avenue North Nashville, Tennessee 37203 Mr. Bob Faas Westinghouse Electric Corp. County Judge P.O. Box 355 Hamilton County Courthouse Pittsburgh, Pennsylvania 15230 Chattanooga, Tennessee 37402 R. L. Gridley Tennessee Valley Authority SN 1578 Lookeut Place Chattanooga, Tennessee 37402-2801 H. R. Harding Tennessee Valley Authority Sequoyah Nuclear Plant P.O. Box 2000 Soddy Daisy, Tennessee 37379 Resident Inspector /Sequoyah NPS c/o U.S. Nuclear Regulatory Comission 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379 H.L. Abercronbie Tennessee Valley Authority Sequoyah Nuclear Plant P.O. Box 2000 Soddy Daisy, Tennessee 37379

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• 5 ENVIRONMENTAL QUALIFICATION OF ELECTRIC EQUIPMENT IMPORTANT T 5.1 Introduction A licensee must demonstrate that equipment that is used to perform a necessary safety function is capable of maintaining functional operability under all service conditions postulated to occur during its installed life for the time it is required to operate. This requirement (which is in General Design Cri-teria (GDC) 1 and 4 of Appendix A and Sections III, XI, and XVII of Appendix B to 10 CFR 50) is applicable to equipment located inside as well as outside con-tainment. More detailed requirements and guidance relating to the methods and procedures for demonstrating this electrical equipment capability are in 10 CFR 50.49, " Environmental Qualification of Electric Equipment Important to Safety for Nuclear Power Plants"; in NUREG-0588, " Interim Staff Position on Environmental Qualification on Safety-Related Electrical Equipment" (which supplements IEEE Standard 323 and various NRC Regulatory Guides and industry standards); and " Guidelines for Evaluating Environmental Qualification of Class IE Electrical Equipment in Operating Reactors" (Division of Operating Reactors (DOR) Guidelines).

5.2 Background

On February 8, 1979, the NRC Office of Inspection and Enforcement (IE) issued to all licensees of operating plants (except those included in the systematic j

evaluation program (SEP)) IE Bulletin (IEB) 79-01, " Environmental Qualification

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of Class IE Equipment." This bulletin, together with IE Circular 78-08 (issued on May 31, 1978), required the licensees to perform reviews to assess the i

adequacy of their environmental qualification programs.

l On January 14, 1980, NRC issued IEB 79-01B, which included the DOR Guidelines j

and NUREG-0588 as attachments 4 and 5. Commission Memorandum and Order l CLI-80-21, issued on May 23, 1980, stated that licensees must meet the DOR

! Guidelines and portions of NUREG-0588 regarding environmental qualification of i

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, safety related electr,ical equipment to satisfy those aspects of GDC 4. Supple-ments to IEB 79-018 further clarified and defined the staff's needs. These supplements were issued on February 29, September 30, and October 24, 1980.

In addition, the staff issued Orders to all licensees dated August 29, 1980 (amended in September 1980) and October 24, 1980. The August Order required that the licensees provide a report, by November 1, 1980, documenting the qualification of safety-related electrical equipment. The October Order required licensees to establish by December 1, 1980, a central file location for the maintenance of all equipment qualification records.

The staff issued a Safety Evaluation Report (SER) on environmental qualifica-tion of safety-related electrical equipment to TVA in mid-1981. This SER directed the TVA to "either provide documentation of the missing qualification information which demonstrated that safety related equipment meets the DDR Guidelines or NUREG-0588 requirements or commit to a corrective action (requali-fication, replacement (etc))." TVA was required to respond to NRC within 90 days of receipt of the SER. In response, TVA submitted additional information regarding the qualification of safety-related electrical equipment. This infor-mation was evaluated for the staff by the Franklin Research Center (FRC) to (1) identify all cases where TVA's response did not resolve the significant qualification issues, (2) evaluate TVA's qualification documentation in accor-dance with established criteria to determine which equipment had adequate docu-mentation and which did not, and (3) evaluate TVA's qualification documentation for safety-related electrical equipment located in harsh environments required for implementation of TMI Lessons Learned. FRC issued a Technical Evaluation Report (TER) on March 31, 1983. The staff issued its SER on April 26, 1983, with the FRC TER as an attachment.

A final rule on environmental qualification of electric equipment important to safety for nuclear power plants became effective on February 22, 1983. This rule, 10 CFR 50.49, specifies the requirements for electrical equipment important to safety located in a harsh environment. In accordance with this rule, equipment for Sequoyah Units 1 and 2 may be qualified to the criteria specified in either the DDR Guidelines or NUREG-0588, except for replacement i

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o equipment. Replacement equipment installed af tnr February 22[1983 must be qualified in accordance with 10 CFR 50.49, using the guidance of Regulatory Guide 1.89, unless there are sound reasons tb the contrary.

The staff met with each licensee for whom FRC had prepared a TER to discuss all remaining open issues regarding environmental qualification, including the acceptablility of the environmental conditions for equipment qualification purposes, if this issue had not yet been resolved.

On May 10, 1984, the staff and TVA met to discuss TVA's proposed method to resolve the environmental qualification deficiencies identified in the staff's April 26, 1983 SER and FRC's March 31, 1983 TER. Discussions also included TVA's general methodology for compliance with 10.CFR 50.49. The minutes of the meeting and proposed method of resolution for each of the environmental qualification deficiencies are documented in submittals by letters dated March 26, December 23, 1985 and January 29, 1986.

On August 21-22, 1985, TVA shut down both Sequoyah units because of concerns that documentation at TVA nuclear sites might be inadequate for environmental qualification of electrical equipment within the scope of 10 CFR 50.49. This decision was based on the results of a TVA Management review of the environ-mental qualification activities for compliance with 10 CFR 50.49 (conducted by TVA staff and Westec Services, Inc.). Based on this decision and the results of the review, TVA initiated an in-depth program to ensure that environmental qualification of all electrical equipment within the scope of 10 CFR 50.49 was established at Sequoyah and all other TVA nuclear sites.

5.3 Evaluation 5.3.1 Summary of Review The staff evaluation of TVA's electrical equipment qualification program is based on the results of a review of: (1) TVA's proposed resolutions of the equipment qualification deficiencies identified in the SER and TER; (2) TVA's compliance with the requirements of 10 CFR 50.49; (3) TVA's Corporate Nuclear Performance Plan, Revision 1, and Sequoyah Nuclear Performance Plan (submitted on July 17, 1986); and (4) the staff's equipment qualification audit on TVA Vol 2 5-3 11/24/86

November 18-22, 1985,- and the staff equipment qualification inspections January 6-17, February 10-14, and June 23-27, 1986, and , 1987.

5.3.2 Proposed Resolutions of Identified Deficiencies

• TVA described itsproposed resolutions for the equipment environmental qualiff-cation deficiencies identified in the SER and the TER in submittals dated March 26 and December 23, 1985, and January 26, 1986. During its May 10, 1984, meeting with TVA, the staff discussed the proposed resolution of each deficiency for each quipment item identified in the TER and found TVA's approach for re-solving the identified environmental qualification deficiencies acceptable. The majority of deficiencies identified were documentaion, similarity, aging, quali-fled life, and replacement schedule. All open items identified in the SER were also discussed, and the staff found TVA's resolution of these items acceptable.

TVA's approach for addressing and resolving the identified deficiencies includes replacing equipment, performing additional analyses, using additional qualifica-tion documentation beyond that reviewed by FRC, obtaining additional qualifica-tion documentation, and determining that some equipment is outside the scope of 10 CFR 50.49, and need not be environmentally qualified (that is the equipment located in a mild environment). The staff discussed the proposed resolutions in detail, on an item-by-item basis, with TVA during the May 10, 1984 meeting.

Replacing or exempting equipment, for an acceptable reason, is clearly an acceptable method for resolving environmental qualification deficiencies.

More lengthy discussions with TVA concerned the use of additional analyses or documentation. Although, during the meeting, the staff did not review the additional analyses or documentation, the staff did dicusss how analysis was being used to resolve deficiencies identified in the TER, and the content of the additional documentation to determine the acceptability of these methods.

On November 18-22, 1985, the staff and a consultant from EG8G Idaho, performed an audit of the Sequoyah electrical equipment environmental qualification binders, and inspected selected equipment. On Jaunary 6-17, February 10-14, June 23-27, 1986 and , 1987, the staff and its consultants from Sandia National Laboratories, inspected the Sequoyah EQ binders and selected equipment, and reviewed Sequoyah's implementation of the 10 CF 50.49 program.

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On the basis of its discussions with TVA, the review of the submittals, and the audit and inspections, the staff finds TVA's approach for resolving the -

identified environmental qualification deficiencies acceptable.

5.3.3- Compliance with 10 CFR 50.49 ,

All equipment that must function to mitigate any design-basis event (DBE) at Sequoyah that causes a harsh environment for the equipment per 10 CFR 50.49 (b)(1) was initially identified. This equipment was determined by identifying all the systems upon which the sqfety analyses in the Final Safety Analysis Report (FSAR) are dependent. Other systems or equipment necessary to support these systems were also identified.

From the safety systems identified above, a survey of the safety-related equip-ment within the harsh environment area of the DBE's was conducted. This survey -

was conducted using electrical instrument tabulations, mechanical piping draw-ings, mechanical heating and ventilation drawings, instrumentation and control drawings, electrical equipment drawings, and conduit and grounding drawings to identify the safety-related components. The equipment qualification was veri-fied by a field survey of the installed components to certify proper correla-tions between the qualification documents and the in-situ equipment.

DBEs in the area covered by 10 CFR 50.49 are high energy line breaks (HELBs),

both inside and outside of containment, and loss-of-coolant accident (LOCAs).

Equipment in the 10 CFR 50.49 program was evaluated for the harsh environments through which it must function and/or not fail. These environments include flooding both inside and outside containment as a result of a DBE.

TVA has also evaluated other accidents in Chapter 15 of the Sequoyah FSAR that did not fit the 10 CFR 50.49 DBE definition as interpreted above but that have the potential to produce environments more severe than those encountered during normal operation or anticipated operational occurrences. These accidents are the waste gas decay tank (WGDT) rupture, the fuel handling accident (FHA), and the steam generator tube rupture (SGTR). These three events do not produce unusual temperature or pressure environments, and the radiation environments associated with them are not sig11ficant. Radiation doses TVA Vol 2 5-5 11/24/86

to equipment necessary for mitigatio'n of these events is less than 104 rads.

The 10 CFR 50.49 DBEs at Sequoyah that produce harsh environments are only those events that are LOCAs, HEL8s inside containment, and HELBs outside containment.

TVA environmental data drawings are design output documents that identify and define the conditions of all harsh zones that contain 10 CFR 50.49 scope equip-ment. M ese harsh zones result from the DBE's. All environmental parameters necessary for design, procurement, and qualification of equipment in accordance with 10 CFR 50.49 are specified on these drawings. These parameters include normal, abnormal, and accident values for temperature, pressure, relative humid-ity, radiation (expressed as a 40 year integrated dose and an accident dose),

flooding level (from a LOCA and HELB including contribution from spray), and spray chemistry.

LOCA and HELB pressure, temperature, and relative humidity profiles are provided. The environmental parameters shown on the drawings are derived from a number of supporting calculations that are referenced on the drawings.

TVA's approach for identifying equipment within the scope of 10 CFR 50.49(b)(1) is in accordance with the requirements of that paragraph, and therefore is acceptable.

The paragraphs below summarize the method used by TVA for identification of electrical equipment within the scope of 10 CFR 50.49(b)(2), non-safety related electric equipment whose failure under postulated environmental conditions could prevent satisfactory accomplishment of safety functions.

Non-safety-related electrical equipment exposed to harsh accident environments must not fail in a manner that can prevent safety-related electrical equipment from performing its safety function. In response to IE Notice 79-22. TVA evalu-ated non-safety related devices for their potential to adversely affect safety-related devices as a result of environmentally induced failures. Flow, control, and logic diagrams for all safety related process systems were reviewed to determine all interfaces with non-safety-related equipment. Datailed wiring diagrams were used if the nature of an interface was not clear from the control TVA Vol 2 5-6 11/24/86

e and logic diagrams. Each interface with non-safety-related equipment was evaluated for its potential to adversely affect safety functions, and the results were documented.

The result of this study showed that six non-Class IE devices (three per unit in the residual heat removal (RHR) system) have the potential to adversely affect RHR. However, failure modes evaluation of these devices concluded that the devices would not adversely affect RHR if their cables were environmentally qualified.

These cables are environmentally qualified and have been added to the approportate binders and the "10 CFR 50.49 List" to ensure their continued qualification.

The evaluation also identified cases where disruptive signals could be generated, but in each case the operator has sufficient indication of the event and sufficient time to take corrective action.

TVA performed separate evaluation of the Class IE power system to investigate the effects of environmentally induced failures. The design basis of the Class IE power systems includes protective features for coordinated, selective clearing of single random faults and overloads. Most failures of non qualified equipment from environmental causes will occur in a random fashion. The Class IE power system is therefore adequately protected by its own design for most environmentally induced failures. The operation of this electrical protection was examined in analyses done to verify the protection of primary containment electrical penetrations and in analyses done to identify associated circuits as defined for 10 CFR 50, Appendix R. The protection has been shown to satisfy its design basis. Submergence and spray effects may, however, cause multiple non qualified electrical equipment and cable termination faults.

This type of failure is outside the design basis of the Class IE power system.

Devices and junction boxes exposed to containment spray or submergence inside containment or to submergence outside containment that are not qualified for these conditions have been identified. Evaluations of the ef fects of multiple faults from these circuits on the ability of the Class IE power system to provide power to essential equipment show that unacceptable degradation of the Class 1E power system would not occur.

The staff finds the methodology being used by TVA acceptable because it provides TVA Vol 2 5-7 11/24/86

F reasonable assurance that equipment'within the scope of 10 CFR 50.49(b)(2) has been identified.

With regard to 10 CFR 50.49(b)(3), TVA evaluated existing system arrangements and identified equipment for the variables defined in RG 1.97, Revision 3. A report outlining the results of the review and schedules for modifications has been submitted to the staff for review. Because the report is still being reviewed, some of the equipment items jointly within the scope of NUREG-0737 and RG 1.97 have been included in the 10 CFR 50.49 scope. When the RG 1,97 report and equipment lists contained therein have been finalized and accepted by the staff, appropriate equipment not already ia the 10 CFR 50.49 scope will be added in accordance with the RG 1.97 implementation schedule.

TVA will complete environmental qualification of the applicable FSAR Class 1E-designed instrumentation and the FSAR post-accident monitoring (PAM) instrumen-tation before plant startup. For those instruments already added to the plant because of a commitment to meet post-THI requirements (NUREGs-0578 and 0737),

TVA will complete its environmental qualification in accordance with the NUREG responses or any extension granted with respect to the NUREG responses.

Presently, for that instrumentation that is not considered operable or not installed but that will be complete by September 1987 because of RG 1.97 or post-THI NUREGs, environmental qualification will be complete when the equipment is installed and operable.

For that instrumentation that exists at the plants but that was not designed as Class IE nor included in the original PAM instrumentation set but that will be Category 1, RG 1.97 instrumentation, TVA will complete environmental qualification in accordance with the implementation schedule for RG 1.97 provided in TVA's response to Generic Letter 82-33 for Sequoyah (September 2, 1987.

l TVA has investigated whether proper consideration of the equipment used in execution of Emergency Operating Instruction (E01) requirements has been l given in the development of the 10 CfR 50.49 equipment scope. The following were considered:

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(1) Does the plant operator have at' his disposal reliable instruments to identify and mitigate the consequences of DBEs?

(2) Have those instruments been marked so as to indicate their importance to the plant operator?

TVA's installed PAM indicators are specifically identified to the main control room operator. The indicators are marked either P1 or P2, which indicates the function these indicators fulfill as PAM channel 1 or PAM channel 2. This method of marking the indicators on the main control room boards shows as their importance (rather than requiring that they be singled out in the plant procedures as being... safety-related).

These installed PAM indicators are served by instruments (e.g., transmitter, etc.) that are qualified to meet the 10 CFR $0.49 requirements. When other activities are implemented (in accordance with NUREG-0700 and RG 1.97),

instruments presently installed but not requiring specific identification and qualification may have to be upgraded.

TVA has concluded that the PAM equipment that will be installed and qualified at plant restart will give the operator the information necessary to identify and mitigate DBEs and will be appropriately marked to indicate its importance.

The staff finds TVA's approach to identifying equipment within the scope of 10 CFR 50.49(b)(3) acceptable because it is in accordance with the requirements of that paragraph.

5.4 Conclusions 1 On the basis of the above evaluation, the staff has reached the following conclusions with regard to the qualification of electric equipment important to safety within the scope of 10 CFR 50.49:

(1) The Sequoyah electrical equipment environmental qualification program complies with the requirements of 10 CFR 50.49.

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(2) TVA's proposed resolutions for each of the environmental qualification deficiencies identified in the staff's SER and the FRC TER are acceptable.

The staff's findings regarding compliance with 10 CFR 50.49 rely on certain modifications / replacements that must be completed for the effected equipment to be qualified. In all cases, TVA is aware of what modifications or replacements are required. However, as a confirmatory action, prior to restart, TVA will be required to certify that the following issues have been completed or resolved:

(1) resolution or staff approval of the main-steam-line break with superheat release and its effect on the environmental qualification of equipment in the east and west valve vault vault rooms (A1, A2, A10, All)

(2) all EQ field work

, (3) mainsteam vault submergence review (4) management review of EQ binders (5) supplemental vendor information (6) cable load study (7) inside containment flood analysis for 5-minute operability (8) verification of instrument accuracy calculation (9) finalization of the EQ master list The staff will verify that these items have been completed.

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DISTRifl0TICri: -

Docket File ~

NRC POR Local POR PRC System fiSIC PWR#4 Readirg VDuncar BJYoungblood Reading TAlexion IVA0P (3) S. Richardson AR '.070 HDenton JTaylor DHayes GZech, RII hGrace LSpessard KDarr SAConnelly Di'uller TNovak DJYoungblood JHolonich CStable TKenyon WLong FKSingh VFocks ACRS (10) occ JPa rtinu CCrtrces Edordan fiReinhart, AR JThct;oton Clfpricht GHubba rd

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