ML18033A423
| ML18033A423 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 10/21/1988 |
| From: | NRC OFFICE OF SPECIAL PROJECTS |
| To: | |
| Shared Package | |
| ML18033A420 | List: |
| References | |
| NUDOCS 8810260398 | |
| Download: ML18033A423 (7) | |
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NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 ENCLOSURE SAFETY EVALUATION BY THE OFFICE OF SPECIAI.
PROJECTS IN REGARD TO VOLUME 3 OF THE BROWNS FERRY NUCLEAR PERFORMANCE PLAN SECTION III.1.0 ENVIRONMENTAL UALIFICATION OF ELECTRICAL E UIPMENT PROGRAM TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT, UNIT 2 DOCKET NO. 50-260
1.0 INTRODUCTION
A licensee must demonstrate that equipment 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 Criteria (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 contain-ment.
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;"
NUREG-0588, "Interim Staff Position on Environ-mental Qualification of Safety-Related Electrical Equipment" (which sypplements IFEF. Standard 323 and various NRC Regulatory Guides and industry standards);
and "Guidelines for Evaluating Environmental Oualification of Class lE Electrical Equipment in Operating Reactors" (Division of Operating Reactors (DOR) Guidelines).
2.0 BACKGROUND
On August 8, 1985, the Office of Nuclear Reactor Regulation issued a Safety Evaluation (SE) for the Browns Ferry Nuclear Plant (BFN), Units 1, 2, and 3 on the environmental qualification of safety-related electrical equipment.
The SE concluded that the BFN Environmental Qualification (EQ) Program was in compliance with the requirement of 10 CFR 50.49 and that the issue of environmental qualifi-cation of electrical equipment important to safety was acceptably resolved.
During July and August 1985, TVA assisted by Westec Services, Inc., conducted a
management review of EQ activities at Sequovah, Browns Ferry and Watts Bar.
This review, completed in August 1985, concluded that qualification documentation had not been established for the large majority of equipment reviewed.
The deficien-cies were judged to be significant, and both systematic and pervasive.
The problems resulted from an unstructured program, lack of adequate guidance and an inconsistent approach between the fragmented organizations involved in the EQ program.
This review led TVA to shut down both units at Sequoyah on August 22, 1985.
In a request for information pursuant to 10 CFR 50.54(f) dated September 17, 1985, the NRC included a specific item related to the BFN EQ program as follows:
"Provide a detailed description of a) the proqram being imp1emented to demonstrate compliance with 10 CFR 50.49 and 38i0260398 88i021 PDR ADOCK 05000260 P
PDC b) the long-term program to assure continued compliance with regulations.
Affirm that the list of equipment required to meet 10 CFR 50.49 is complete."
TVA responded on August 28, 1986, with the Browns Ferry Nuclear Performance Plant (NPP).
Section III.1 of the BFN NPP specifically addressed this concern.
On October 3, 1986, the NRC requested additional information on the BFN NPP of which some questions were Eg program related.
TVA responded with Revision 1 to the NPP on June 23, 1987.
TVA has yet to affirm that the 10 CFR 50.49 list of equipment is complete.
TVA is also expected to certify, prior to restart, that Eg requirements have been satisfied.
3.0 EVALUATION The staff evaluation of TVA's BFN electrical equipment qualification program is based on the results of: (1) TVA's compliance with the requirements of 10 CFR 50.49; (2) TVA's Browns Ferry NPP, Revision 1 (submitted on June 23, 1987);
and (3) the staff's equipment aualification inspection on May 9-13, 1988.
The evaluation included a complete review of the Eg program as described in the NPP and implementing program procedures/instructions.
This complete review was performed since TVA had made significant changes to their Eg program since issuance of the NRC's August 1985 safety evaluation of the program.
3.1.
10 CFR 50.49 List Licensees are required to maintain an up-to-date list of the equipment that must be qualified under 10 CFR 50.49.
At BFN, a systems analysis was conducted to identify for each Chapter 14 Design Basis Accident (DBA) of the Final Safety Analysis Report (FSAR),
a list of those equipment items
("end devices")
which'ust either operate or "stay-as-is" to ensure completion of safety-related functions as defined in 10 CFR 50.49 (including BFN commitments to Regulatory Guide (R.G.) 1.97).
This list contained the "end-devices" (pumps, valves, motors, etc.) which were essential for completion of the safety action.
A
- second, more extensive list was generated by researching drawings in order to determine the support equipment such as power supplies,
- cables, terminations, logic systems, control systems, and electrical distribution systems'which are necessary to ensure completion of each end-device's safety-related function.
The expanded list was reduced by a failure analysis which eliminated those components whose failure would not prevent achievement of the required safety action.
This list was then further reduced by eliminating equipment which is located in a mild environment as defined in 10 CFR 50.49(c).
One final cut was made to eliminate those items which are located in an environment which becomes harsh for certain accidents but remains mild for other accidents and the equip-ment is only required to contribute to the safety function during these "other" accidents.
The DBAs evaluated as part of the 10 CFR 50.49 List development include (1)
Loss of Coolant Accident, (2) High Energy Line Break Inside Containment (which is the intermediate and small break LOCA), and (3) High Energy Line Break Outside Containment.
These are abbreviated as the LOCA, HELB-IPC, and HELB-OPC.
The 10 CFR 50.49(b)(2) category of nonsafety-related electrical equipment whose failure could prevent accomplishment of the safety function by the safety-related equipment was incorporated in the first expansion of the list.
During this expansion, a detailed circuit analysis of the drawings was performed to determine the necessary ancillary devices needed to support the required operating mode of the end-device (e.g., valve required to go closed and stay closed or valve required to remain open).
The 10 CFR 50.49(b)(3) category of post-accident monitoring equipment was addressed during the review of instrumentation and control drawings.
Instruments shown on control drawings with associated indicators in the control room were correlated with the licensee's submittals of April 30, 1984 and May 7, 1985, regarding compliance with R.G. 1.97.
The staff's safety evaluation of BFN's compliance with the requirements of R.G.
1.97 was transmitted to TVA on June 23, 1988.
The evaluation documented seven variables which were not qualified in accordance with 10 CFR 50.49 and concluded that BFN should include the variables in the Eg program.
These variables are:
Core spray flow Low pressure coolant injection system flow Residual heat removal (RHR) system flow RHR heat exchanger outlet temperature Cooling water temperature to engineered safety feature (ESF) system components Cooling water flow to ESF system components Emergency ventilation damper position Browns Ferry was requested to confirm that these variables have been qualified in accordance with 10 CFR 50.49.
During the May 9-13,
- 1988, NRC Eg inspection, the inspectors identified one inspection follow-up item
( IFI), 50-259,260,296/88-11-04, pertaining to specific outstanding items needing correction/clarification in documentation supporting the 10 CFR 50.49 list.
This IFI is documented in NRC Inspection Report (IR) 50-259,260,296/88-11, dated September 1,
1988.
>lhile the issues of this IFI are not considered significant, relative to the 10 CFR 50.49 list process, the issues must be, closed prior to BFN restart.
Based on the staff's evaluation.and results of the May 1988 inspection, the staff finds that the methods used by BFN for identification of electrical equipment within the scope of paragraphs (b)(1), (b)(2), and (b)(3) of 10 CFR 50.49 is in accordance with the requirements of those paragraphs, and therefore is acceptable.
However, the following items must be completed prior to restart of BFN:
(a)
Finalize the 10 CFR 50.49 list (b)
Resolve the issue identified in the R.G.
1.97 safety evaluation relative to the qualification of seven variables
4 (c)
Close the issues identified in the Eg IR relative to IFI 50-259,260,296/88-11-04 3.2 gualification Methodology and Documentation I
Browns Ferry and TVA's qualification methodology is described in the licensee's Appendix C to DI-125.01, "Program Requirements for Environmental gualification of Electrical Equipment in Harsh Environments" (DI-125.01 superseded the Eg Project Manual EgP-01 discussed in the BFN NPP).
As stated in this
- appendix, the preferred method of qualification is defined as testing of an identical component under identical conditions or under similar conditions with supporting analysis.
Justification for any exception to this method is required by Appendix C to be included in the qualification file.
Detailed guidance is included in DI-125.01 regarding similarity analysis data, extrapolation data, interpolation, and other supporting analyses which would provide acceptable alternatives to the preferred method.
Browns Ferry's Eg program provides for the preparation of an environmental qualification data package (E(DP or E(} binder) for each equipment type to demonstrate that the eauipment is environmentally qualified for its application and that design basis safety functions can be accomplished.
An equipment type refers to electrical equipment categorized by manufac-turer and model(s) which is representative of all identical equipment in a plant area(s) potentially exposed to the same bounding environmental conditions during and after a design basis accident (e.g.,
Rosemount electronic pressure transmitters, Model 1153 Series D, 1'ocated inside containment).
All auditable documentation which supports environmental qualification for the equipment type is compiled and placed in the Eg Binder or referenced therein.
Each Eg Binder consists of:
1.
Title page referring to the vendor and equipment types 2.
Revision log 3.
Table of Contents 4.
Tab A - Identification of equipment comprising the equipment type 5.
Tab B - Checklist for evaluation of environmental qualification including summary and conclusion 6.
Tab C - Analyses and justification 7.
Tab D - gualification documents 8.
Tab E - Miscellaneous documents and correspondence 9.
Tab F - Field verification data 10.
Tab G - gualification maintenance data sheets 11.
Tab H - Vendor instruction manual 12.
Tab I - Vendor drawing for equipment 13, Tab J - Evaluation of NRC.circulars, notices, bulletins, and vendor bulletins The licensee learned through expe~ience at Sequoyah that the as-built condition of qualified equipment sometimes did not agree with documentation in the qualification binders and that installation and subsequent maintenance activities may invalidate qualification.
To alleviate this problem at
- BFN, the Eg program includes field verification of environmentally qualified equipment.
This field effort covers verification of previously installed equipment and verification following installation'of equipment installed by modifications.
Browns Ferry's activities in the area of maintenance are discussed in paragraph 3.3.
While the May 1988 NRC inspection identified some IFIs and Unresolved Items (URIs) (see IR 50-259,260,296/88-11) in the implementation of the Eg program at BFN, the staff evaluation has determined that BFN has established a program with appropriate implementing procedures and controls to ensure that all electrical equipment within the scope of 10 CFR 50.49 is qualified to the requirements of 10 CFR 50.49.
Browns Ferry must resolve the IFIs and URIs of the May inspection prior to restart.
3.3 Maintenance In order for a licensee to maintain the qualified status of equipment throughout the equipment's life in the plant, it is necessary t'o identify qualification maintenance requirements which must be met.
At BFN, TVA has included identification of aualification maintenance requirements (Tab G of the EgDPs) as part of the documentation included in the qualification binders.
This information is identified on qualification maintenance data sheets (gMDSs).
The gMDSs define all required Eg maintenance requirements and provide descriptions of qualified spare parts.
The gMDSs are provided to plant maintenance organizations which review all requirements to ensure that required maintenance can be performed (including required warehouse maintenance),
that gMDS requirements are merged with other ongoing maintenance activities such that qualification is maintained, that replacement intervals and trending programs are developed, and that all gMDS maintenance is scheduled and performed.
The BFN E(} program further requires that any desired changes to essential qualification maintenance requirements must be coordinated with the Eg organization prior to implementation.
The BFN program emphasizes that qualification maintenance activities do not drive or substitute for the total overall maintenance program.
gualification maintenance activities are only one part of BFN's overall maintenance program.
In addition to establishing the requirements for qualification maintenance, the Eg program requires that the maintenance status of all equipment 'within the scope of 10 CFR 50.49 be verified prior to restart.
This includes a review of past maintenance activities to ensure that they have not invalidated the qualified status of installed qualified equipment.
The staff evaluation determined that BFN has established a program and procedures with adequate controls to ensure that equipment qualified to the requirements of 10 CFR 50.49 is maintained in a qualified status throughout its life in the plant.
4.0 CONCLUSION
On the basis of the above evaluation, the staff has concluded that the Browns Ferry electrical equipment qualification program for electric equipment located in harsh environments complies with the requirements of 10 CFR 50.49.
Full implementation of the program is pending completion of certain activities such as equipment replacement,'modifications, engineering analysis, and documentation.
The licensee has a tracking system for these activities and is following their completion.
In addition to these activities, BFN is required to ensure that the following activities identified in this safety evaluation are resolved prior to restart:
(a)
Finalize the 10 CFR 50.49 list (b)
Resolve the issue identified in the R.G.
1.97 safety evaluation relative to the qualification of the following seven variables:
Core spray flow Low pressure coolant injection system flow Residual heat removal (RHR) system flow RHR heat exchanger outlet temperature Cooling water temperature to engineered safety feature (ESF) system components Cooling water flow to ESF system components Fmergency ventilation damper position (c)
Close the issues related to the IFIs and URIs identified in the Eg Inspection
- Report, 50-259,260,296/88-11, dated September 1,
1988 As a confirmatory item, prior to restart, BFN is required to certify to the NRC that the 10 CFR 50.49 list is complete and all electrical equipment within the scope of 10 CFR 50.49 is qualified to the requirements of 10 CFR 50.49.
The NRC will continue to monitor implementation of the BFN Eg program and procedures through future inspections.
Principle Contributors:
Charles Brooks George Hubbard Dated: