ML20079C072
| ML20079C072 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 06/13/1991 |
| From: | Zeringue O TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9106180353 | |
| Download: ML20079C072 (17) | |
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t Tennuu e Va% A,2vNy Post O%e Bca M0 DuaM A,.d.en y W O.J *lko"Zenngue v.ce %sont o.w.s re v op..es JUN 13 1991 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Gentlemen:
In the Matter of ) Docket Nos. 50-259 Tennessee Valley Authority ) 50-260 50-296 BROWNS PERRY NUCLEAR PLANT (BFN) - DESIGN BASELINE VERIFICATION PROGRAM (DBVP)
Reference:
TVA letter, dated January 9,1991, " Plans for the Return to Service of BFN Units 1 and 3" As part of the referenced letter, TVA committed to provide the NRC staff with the action plan for implementing a DBVP on Browns Ferry Units 1 and 3. Enclosure 1 to this letter: 1) Provides a summary of the issue,
- 2) Gives an overview of the DBVP, 3) Reviews the restart and post-restart portions of the Unit 2 DBVP, 4) Discusses lessons learned, and
- 5) Describes how the DBVP will be implemented on Units 1 and 3. This submittal is provided for informational purposes only. No NRC action is specifically requested.
A summary list of commitments contained in this letter is provided in Enclosure 2. If you have any questions, please contact Patrick P. Carier, Manager of Site Licensing, at (205) 739-3570.
Very truly yours, TENNES EE VALLEY AUTl!0RITY
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Edclosures cc: See page 2 9106160353 910613
{DR ADOCK 05000259 PDR MO/
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2 U.S. Nuclear Regulatory Commiosion i
JUN 13 1991 cc (Enclosures):
Ms. S. C. Black, Deputy Director Project Directorate 11-4 U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike, Rockville, Maryland 20852 NRC Resident Inspector Browns Ferry Nuclear Plant Route 12, Box 637 Athens, Alabama 35609-2000 Mr. Thierry M. Ross, Project Manager U.S. Nuclear Regulatory Commissicn One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Mr. B. A. Wilson, Project Chief U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323
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4 ENCLOSURE 1 BROWNS FERRY NUCLEAR PLANT (BFN)
DESIGN BASELINE VERIFICATION PROGRAM (DBVP)
ISSUE SUMMARX The BFN DBVP was established to resolve several problems related to design control that had occurred at BFN. These problems were:
- 1) The original design control program allowed a set of as-constructed drawings to be maintained by plant operations and a separate set of as-designed drawings to be maintained by engineering. Failure to effectively :ontrol changes using this two drawing system caused a loss of configuration control which resulted in engineering design and evaluations being performed using drawings which did not reflect the as-constructed configuration of the plant.
- 2) The plant configuration was not reconciled with the design basis because the plant's design basis was scattered among many documents which were not readily available for use.
- 3) External reviews and studies indicated weaknesses in some plant modifications which were implemented after the plant became operational.
OVERVIEW OF THE DESIGN BASELINE VERIFICATION PROGRAM The objectives of the Unit 2 DBVP werw to re-establish the design basis and evaluate the plant configuration to ensure that it satisfios the design basis.
This was accomplished by:
e Verifying the functional adequacy of the plant configuration. ,
e Ensuring that the configuration of these systems is supported by engineering analysis and documentation.
- Providing confidence that the plant configuration is in conformance with licensing commitments.
The essential elements of the overall program were as follows:
e Verification of the plant configuration.
l e Reconciliation of the configuration to engineering design i documents including essential calculations.
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- Reconciliation of the configuration to the Browns Ferry Final Safety Analysis Report (FSAR) and licensing commitments.
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4 ENCLOSURE 1 #* 8' # #"
BROWNS FERRY NUCLEAR PLANT (BFN)
DESIGN BASELINE VERIFICATION PROGRAM (DBVP)
(CONTINUED) e Performance of system evaluation for the systo:a configuration, e Issuance of revised key plant drawings for the required systems consistent with the plant configuration. ,
e Implementation of improved design change control.
t OVERVIEW OF THE UNIT 2 RESOLUTION l
The DBVP is being implomonted on Unit 2 in two phases:
Phase I was completed before restart of Unit 2 and included the evaluation of those systems and portions of systems required for safe shutdown. These systems, or portions thereof, were identified by determining the safety functions necessary to mitigate postulated design basis accidents, abnormal operational transients, or special events which are discussed in Chapter 14 of the FSAR. Specifically, Phase I DBVP included those systems or portions of systems required for reactor pressure vessel integrity, primary or secondary containment integrity, j core cooling, reactor pressure vessel over-pressure relief, decay heat removal (torus cooling), and reactivity control.
Phase II will be completed prior to restart from the next Unit 2 refueling outage. This phase extends the DRVP to include the balance of safety related functions of systems or portions of systems that are utilized in abnormal operational transients and special events not covered by Phase I.
l DETAILS OF THE UNIT 2 RESOLUTION 1
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The methodology utilized for Phase I of the Unit 2 DBVP was as follows:
- 1) Establish the design basis input for the evaluation, i
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- 2) Establish the plant configuration, l 3) Evaluate the configuration to the design basis, and
- 4) Issue the outputs.
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ENCLOSURE 1 BROWNS FERRY NUCLEAR PLANT (BFN)
DESIGN BASELINE VERIFICATION PROGRAM (DBVP)
(CONTINUED)
Each of these steps are reviewed in greater detail below. Alen included is a discussion of the independent reviews waitch were performed on Phase I of the Unit 2 DBVP, a summary of the plan for Phase II (the post-restart effort), and a summary of the more significant TVA/NRC correspondence which documents the resolution of Phase I of this issue for Unit 2.
STEP 1 - ESTABLISH DESIGN BASIS INPUT The dasign basis input for Unit 2 consisted of a commitments / requirements data base, the General and System Design Criteria, System Requirements Calculations to support the Safe Shutdown Analysis (SSA), the set of essential calculations within the scope of the Design Baseline and Verification Program, and functional testing requirements. This was accomplished in the following manner:
A. Commitments / Requirements Data Base The licensing commitments made throughout the life of the plant and design requirements necessary to achieve safe shutdown were documented in a data base.
B. Design Criteria Documents The Design Criteria Documentu (DCDs) were developed from a search of the licensing commitments and design requirements data base, and from the review by senior level engineers. The DCDs serve as the basis for engineering requirements and were used to determine plant modifications required before restart and to evaluate the ayatem configurations.
C. System Requirements The SSA was based on the FSAR Chapter 14 requirements and identified the accidents, abnormal operational transients, and special events from which the plant must be able to achieve safe shutdown. The SSA also identified the system functions required to achieve safe shutdown for the applicable operating states.
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ENCLOSURE 1 BROWNS FERRY NUCLEAR PLANT (BFN)
DESIGN BASELINE VERIFICATION PROGRAM (DBVP)
(CONTINUED)
The System Requirements Calculations (SRCs) were based on the SSA and identified the systems or portions of systems that perform the shutdown for each event. The SRCs identified the boundaries for the system and provided the system modes and components for shutdown. The SRCs were used to establish the list of essential calculations and establish the scope for the program.
D. Establish Essential Calculations Phase I of the Unit 2 DBVP specified the essential calculations needed to verify the adequacy of the design within the safe shutdown boundary and determined if the calculations existed and were adequate to support the design output. If calculations were not in place or were determined to be inadequate, new calculations were developed. The DDVP ensured that the calculations met the safe shutdown design basis and were in place to support the design requirements for the DBVP scope.
E. Establish Test Requirements The test requirements for verification of system capabilities were developed ueing the SRCs and DCDs. The Baseline Test Requirements Documents established the testing to support the requirements of the D8VP.
. STEP 2 - ESTABLISH CONFIGURATION The plant configuration for Unit 2 was established through the functional walkdown of the Flow, Control and Single Line drawings, review of other
, programs, verification of electrical logic, and testing. This was accomplished in the following manner:
A. Functional Walkdown The flow, control, and single line drawings defined the portion of the
, plant that was functionally walked down to document the plant configuration. This ef fort verified the fur etional configuration of the i
systems within the boundaries defined in the SRCs. Arrangement of components, the type of components, and nameplate data en the components were addressed. The as-constructed drawings were marke' up to reflect I the actual functional configuration.
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ENCLOSURE 1 BROWNS FERRY NUCLEAR PLANT (BFN)
DESIGN BASELINE VERIFICATION PROGRAM (DBVP)
(CONTINUED)
The results were used in the functional evaluation of drawings, to issue revised AC drawings, and to reconcile nameplate data on the Instrument Tabulation and Valve Marker Tabulation drawings. (Setpoint data was verified by calculation.)
B. Other Program Walkdowns other programs (e.g., Environmental Qualification and Appendix F) performed field verification walkdowns for Unit 2 restart. The information gathered during these walkdowns was assessed and used, as required, in determining the functional plant configuration.
C. Verification of Electrical Logic Electrical systems and electrical aspects of mechanical systems were verified by one of two methods e Schematic / elementary diagrams were functionally verified by tests and review of existing documents.
. Single lines were verified by a combination physical walkdown and functional testing.
Based on these results, the electrical schematics were verified as CCDs and issued.
D. Testing Testing was performed no part of the Restart Test Program to test specifications based on the Laseline Test Requirements Documents.
Page 6 of 14 ENCLOSURE 1 BROWNS FERRY NUCLEAR PLANT (BFN)
DESIGN BASELINE VERIFICATION PROGRAM (DBVP)
(CONTINUED)
STEP 3 - EVALUATE CONFIGURATION System Evaluation Reports (SYSTERs) were prepared for the systems within the scope of Phase I of the Unit 2 DBVP. A SYSTER is an evaluation of the current plant configuration (as depicted by the fic1d verified CCDs) versus the system functional requirements (as specified by the design critoria, TSAR, SSA, and system requirements calculations). Differences between the plant configuration and the system functional requirements were evaluated and punchlisted for closure prior to declaring the affected portion of the system operable. A final report was issued to demonstrate the plant met its safe-shutdown design basis.
A review of change documentation was performed to determine if the partially implemented and unimpienented changos should be incorporated in the plant to satisfy the design basis. This review identified those changes required before restart.
A. Functional Evaluation of Drawings Drawings which were issued as Configuration Control Drawings (CCDs) were reviewed to ensure they accurately depicted the system functions. The as-designed drawings were compared to the revised as-constructed drawings and the differences were reconciled. Differences required an Engineering Change Notice / Design Change Notice (ECN/DCN) to document the configuration. Any deviations from the design basis were identified on a punchlist and the resolution specified.
B. Significant Condition Report /Nonconformance Report / Condition Adverse to Quality Report (SCR/NCR/CAQR)
A review was performed to ensure adequate corrective actions were identified for SCRs/NCRs/CAQRs within the Phase I scope and that the corrective actions satisfy the design basis. Open SCR/NCR/CAQRs were closed in accordance with the TVA Condition Adverse to Quality Process.
Closed SCR/NCR/CAQRs not supported by an ECN/DCN were evaluated.. The results of this review were included in the SYSTER and corrective action was initiated as required.
ENCLOSURE 1 " ' # ##
BROWNS FERRY NUCLEAR PLANT (BFN)
DESIGN BASELINE VERIFICATION PROGRAM (DBVP)
(CONTINUED)
C. Evaluation of Other Program Scopes The work performsd by other restart programs (e.g., electrical and seismic issues) was reviewed to determine the portion that could be used to satisfy DBVP requirements. Where applirsolo, cre,dit was taken for other programs and documented in the SYSTERs.
D. Evaluate Accep; ability of Unimplemented or Partially Implemented Changes.
Change documentation was reviewed on those systems and portions of systems required for safe shutdown to ensure that the changes required to meet the design basis were implemented in the plant prior to restart.
Changes that were not fully implemented at restart required that a revised Unreviewed Safety Question Determination review be performed based on their status at restart.
Portions of changes not required for restart were evaluated in accordance ilth the design change control process.
E.- Component Nameplate Data Data collected by walkdowns and records research were used as required in the performance of the system evaluations to determine whether systems (or portions of systems) met the design basis.
F. . Evaluate Configuration Through Testing.
The Test Specifications prepared in the Restart Test Program ware reviewed in the DBVP to ensure that the tests would verify the required characteristics of the configuration. DBVP evaluated the configuration against the requirements of the SRCs. If testing determined that the
. plant configuration did not satisfy the requirements of the SRCs, a CAQR was issued and either the design basis was revised or the configuration was modified by the change control process.
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ENCLOSURE 1 #*8' 8 # 'd BROWNS FERRY NUCLEAR PLANT (BFN)
DESIGN BASELINE VERIFICATION PROGRAM (DBVP)
(CONTINUED)
G. Identify Open Items During the DBVP, some open items were identified which needed to be scheduled and tracked through completion, for example, unverified assumptions, test discrepancies, and the need for supplemental walkdowns. A punchlist was maintained for all open items which indicated the action plan and the organization responsible for resolution.
STEP 4 - ISSUE OUTPUTS A. Resolve Open Items The resolution of open items included verifying assumptions, reviewing test results, evaluating changes implemented subsequent to the walkdowns and tests, and other pre-restart open items. Supporting essential calculations required before restar; were completed and issued.
B. Issue Drawings CCDs were ise.ad to document the DBVP evaluated plant configuration.
For Unit 2 restart, the portions of systems within the safe shutdown boundaries were evaluated.
C. Schematic / Elementary Diagrams The schematic and elementary diagrams were updated to reflect the functional configuration of the plant as determined from testing, drawing comparison, and walkdown data.
D. System Evaluation Reports /Unreviewed Safety Question Determination SYSTERs were prepared to address each system. The SYSTERs were prepared from the evaluations described previously in Step 3. Where it was determined that the actual plant configuration is different than the licansed configuration, a Unreviewed Safety Question Determination was performed.
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ENCLOSURE 1 # ' '"
BROWNS FERRY NUCLEAR PLANT (BFN)
DESIGN BASELINE VERIFICATION PROGRAM (DBVP)
(CoNTINUF.D)
, E. Final Report The results and conclusions of the Phase I program were documented in a final report which was submitted to the Director, Division of Nuclear Engineering. This report documented the Phasi I evaluation scope, objectives, program description, and findings.
INDEPENDENT REVIEWS Independent reviews of the Phase 1 DBVP were performed on a sampling basis by a team of experienced technical personnel. The objectives of the reviews were to:
o confirm and validate that engineering activities were conducted in accordance with the approved program plan and procedures established for DBVP.
- Confirm functional and technical adequacy of system evaluations and completeness / correctness of supporting documentation.
e Verify that corrective actions resulting from these evaluations had been documentud and properly implemented or scheduled for post-restart.
This review provided added assurance that the engineering activities associated with the program were conducted in a technically adequate manner ,
and in accordance with the written procedures prepared specifically for the DBVP effort.
Ut(IT 2 PHASE II DBVP The Phase II portion of the Unit 2 DBVP includes implementation of the modifications to safety systems which were not required for restart, completion and revision of the design criteria documentation, and completion of system evaluations for identified post-restart system safety related functions. Phase II will be completed prior to the restart of Unit 2 from the next refueling outage. The additional events to be covered by Phase II will be operational transients, external events, and special events that are not specifically addressed in Chapter 14 of the FSAR. Also, the improved design change control process will continue to ensure compliance with the design basis is maintained.
l ENCLOSURE 1 BROWNS FERRY NUCLEAR PLANT (BFN)
DESIGN BASELINE VERIFICATION PROGRAM (DBVP)
(CONTINUED)
TVA/NRC CORRESPONDENCE The following is a summary of the significant TVA/NRC correspondence which documents the resolution of this issue for Unit 2. This summary is provided, in part, to assist the NRC Staff if additional detailed historical information is required.
TVA submitted Revision 0 of the DBVP to the NRC by letter dated March 13, 1987. Subsequent revisions of the DBVP were submitted in letters dated July 10, 1987, and March 25, 1988. The NRC Staff concluded in its December 8, 1988 Safety Evaluation that this program contained the essential elements to assess and re-establish the design basis and evaluate the plant's configuration to ensure that it satisfied the design basis. However, NRC monitoring of the implementation of the program would continue. Acceptability of the program is also documented in Section 2 of NUREG-1232, Volume 3, Safety Evaluation Report on the Browns Ferry Nuclear Performance Plan, dated April 14, 1989, NUREG-1232, Supplement 1, dated October 24, 1989, and in Supplement 2, dated January 23, 1991.
Implementation of the DBVP at BFN Unit 2 was the subject of NRC inspections which are documented in Inspection Reporte 87-36, dated January 21, 1988; 88-07, dated September 8, 1988; and 89-07, dated June 30, 1989. TVA provided additional information in response to these inspection reports by letters dated April 20, 1988, November 3, 1988, April 18, 1989 and August 22, 1989.
TVA also submitted a list of the systems to be included in Phase II of the Unit 2 DBVP by letter dated May 3, 1991.
TVA provided a summary of the closure of the majority of the DBVP Phase I commitments in its April 16, 1991 letter. Notification of the completion of the remaining Phase I commitments was provided by TVA letter, dated May 14, 1954.
t ENCLOSURE 1 #*8' '"
BROWNS FERRY NUCLEAR PLANT (BFN)
DESIGN BASELINE VERIFICATION PROGRAM (DBVP)
(CONTINUED)
LESSONJ LEARNED FROM THE UNIT 2 DBVP As discussed previously, the Unit 2 DBVP is being performed in two phases.
Phase I addressed the systems (or portions of systems) which are required for safe shutdown of Unit 2. This phase was completed prior to Unit 2 restart.
Phase II will address the remainder of the safety related systems. This phase will be completed prior to Unit 2 restart from the next refueling outage.
Completion of the DHVP for Units 1 and 3 prior to restart eliminates the need to delineate the break between the Phase I and Phase II portions.
The identification and reconciliation of differences between the as-designed ,
and as-constructed drawings by the Unit 2 DBVP was an extensive effort. The Units 1 ind 3 DBVP will not explicitly identify and reconcile differences between the as-designed and as-constructed drawings. Verified as-constructed drawings for Units 1 and 3 will be generated from walkdown data. CCDs will be generated'by. evaluation of these verified as-constructed drawings against the design basis and reconciliation of any discrepancies identi.fied.
UNITS 1 AND 3 DBVP The Unita 1 and 3 DBVP will consolidate the two-phase (pre- and post-restart) approach performed on Unit 2 and will be completed prior to the restart of Units 1 and 3, respectively. This consolidated DSVP will be performed using the four basic steps discussed above for the Unit 2 DBVP:
- 1) Review of design basis documents and re-establishment of the design basis,
- 2) Defining the functional configuration of the systems and components within the Units 1 and 3 DBVP boundary, l
- 3) Reconciliation of the functional configuration with the re-established design basis, and
- 4) The issuance of required documentation and corrective actions.
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BROWNS FERRY NUCLEAR PLANT (b.N)
DESIGN BASELINE VERIFICATION PROGRAM (DBVP)
(CONTINUED)
The Unit 3 DBVP will be implemented prior to the restart of Unit 3 and will address the operation cf Unit 2 and/or Unit 3. The Unit 1 DBVP will be implemented prior the restart of Unit 1 and will address the operation of any combination of the three units.
Wherever possible, the Units 1 and 3 DBVP will make use of the design basis documentation which is being generated as part of the Unit 2 DBVP. The Unita 1 and 3 DBVP will refine the process implemented for Phase I of the Unit 2 DBVP and will address the design basis implications of multi-unit operation using shared systems and components. Deviations from the Unit 2 implementation precedent are discussed below. Also included is a discussion of the independent reviews which will be performed on the Units 1 and 3 DBVP.
STEP 1 - REVIEW OF DESIGN BASIS DOCUMENTS AND RE-ESTABLISHMENT OF THE DESIGN BASIS The Units 1 and 3 DBVP will generate input data similar to the Unit 2 program, with minor enhancements as noted belows e The commitments / requirements database utilized by the Unit 2 DBVP will be updated and reviewed to determine applicability of the commitments and requirements to Units 1 and 3. Any commitments or requirements which are unique to Units 1 and/or 3 will-be identified and incorporated into the design basis.
e- The essential calculations needed to verify the adequacy of the design of the Units 1 and 3 safety related systems, structures, and components will be identified and generated. Existing calculations will be revised to address Units 1 and 3 whenever possible.
STEP 2 - DEFINING THE FUNCTIONAL CONFIGURATION OF THE SYSTEMS AND COMPONENTS WITHIN THE UNITS 1 AND 3 DBVP BOUNDARY The methodology used to establish the as-constructed plant configurations for Units 1 and 3 will be the same as that used for Unit 2.
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ENCLOSURE 1 BROWNS FERRY NUCLEAR PLANT (BFN)
DESIGN BASELINE VERIFICATION PROGRAM (DBVP)
(CONTINUED)
STEP 3 - RECONCILIATION OF THE FUNCT3ONAL CONFIGURATION WITH THE RE-ESTABLISHED DESIGN BASIS The methodology used to evaluate the as-constructed plant configurations for Units 1 and 3 will be the same as that used for Unit 2 with minor differences
- . as noted belows e The Units 1 and 3 DBVP will not evaluate and reconcile differences between the as-designed and as-constructed drawings as was done for the Unit 2 DBVP. Walkdown data for Units 1 and 3 will be used to generate verified as-constructed drawings. The drawings will be evaluated against the design basis and, following the resolution of any discrepancias identified, issued as CCDs.
STEP 4 - THE ISSUANCE OF REQUIRED DOCUMENTATION AND CORRECTIVE ACTIONS The design output documents issued by the Units 1 and 3 DBVP will be similar to the documents issued for Unit 2 with minor enhancements as notod below:
- The design criteria documentation generated for Unit 2 will be revised to include Unita 1 and 3 prior to the restart of each unit. The revisions will be generated by validating the Unit 2 documentation as applicable to Units 1 and 3 and incorporating any unique commitments or requirements. Where differences exist between units, they will be specifically documented in the revised design criteria.
INDEPENDENT REVIEW The TVA Restart Quality organization and Engineering will be responoible for the performance of independent reviews of the Unit 1 and 3 DBVP. These independent reviews will be performed on a sampling basis and will consist of a series of planned audits, technical assessments, and design reviews of the DBVP process and key deliverables.
The objective of these reviews will be the same as those for the independent assessments performed for the Unit 2 DBVP. These reviews will provide added assurance that the Unit 1 and 3 DBVP activities are conducted in a technically adequate manner and in accordance with the written procedures prepared for the Unit 1 and 3 DBVP effort.
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1 BROWNS FERRY NUCLEAR PLANT (BFN)
DESIGN BASELINE VERIFICATION PROGRAM (DBVP) l (CONTINUED)
CONCLUSION Minor changes in the implementation of this program on Units 1 and 3 have been
.made to incorporate lessons learned from the Unit 2 precedent. Completion of the DBVP prior to next refueling outage for Unit 2 and prior to the restart of Units 1 and 3, respectively, will ensare thats the plant satisfies the design basis; safety related systems, structures, and components are supported by engineering analysis and documentation; and the plant configuration is in conformance with TVA's licensing commitments.
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ENCLOSURE 3 BROWNS FERRY NUCLEAR PLANT
SUMMARY
OF COMMITMENTS
- 1) The Units I and 3 DBVP will consolidate ti = .ao p;.9ea (pro- and post-restart) approach performed on Unit 2 and will be cc.:r$ '..J r uior to the restart of Units 1 and 3, respectively.
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