ML18038B108
| ML18038B108 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 01/19/1995 |
| From: | Salas P TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-88-20, NUDOCS 9501260267 | |
| Download: ML18038B108 (19) | |
Text
P RICHERI~Y 7
(ACCELERATED RIDS PROCESSING)~
REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:9501260267 DOC.DATE: 95/01/19 NOTARIZED: NO
'OCKET FACIL:50-259 Browns Ferry Nuclear Power Station, Unit 1, Tennessee 05000259 50-260 Browns Ferry Nuclear Power Station, Unit 2, Tennessee 05000260 50-296 Browns Ferry Nuclear Power Station, Unit 3, Tennessee 05000296 AUTH.NAME AUTHOR AFFILIATION SALAS,P.
Tennessee Valley Authority RECIP.NAME RECIPIENT AFFILIATION R
Document Control Branch (Document Control Desk)
SUBJECT:
Provides updated schedule for submittal of BFN expanded (multi-unit) PRA
& portions of IPEEE,per GL 88-20.
DISTRIBUTION CODE:
A011D COPIES RECEIVED: LTR t ENCL i
SIZE:
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TITLE: Generic Ltr 88-20 re Individual Plant Evaluations NOTES:
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1 RECIPIENT ID CODE/NAME WILLIAMS,J.
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U NOTE TO ALL"RIDS" RECIPIENTS:
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LTTR 24 ENCL 24
Tennessee Valley Authority, Post Oifice Box 2000. Decatur, Alabama 35609 January 19, 1995 U.S. Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of Tennessee Valley Authority Docket Nos.
50-259 50-260 50-296 BROWNS FERRY NUCLEAR PLANT (BFN) - SCHEDULE FOR SUBMZTTAL OF THE EXPANDED (MULTI-UNIT) PROBABILISTZC RISK ASSESSMENT (PRA)
AND PORTIONS OF THE INDIVIDUALPLANT EXAMINATIONOF EXTERNAL EVENTS (IPEEE)
This letter provides an updated schedule for the submittal of the BFN expanded (multi-unit) PRA and portions of the IPEEE.
The current committed multi-unit PRA submittal date is
~January 18, 1995.
Due, in part, to a recent request from NRC to expand the scope of the multi-unit PRA, this current commitment date is being rescheduled to April 14, 1995.
This date has been discussed with the NRC Project Manager for BFN.
The current. committed submittal date for the BFN Unit 2 internal fires and BFN Units 1, 2, and 3 high winds, external
- floods, and transportation and nearby facility accidents portions of the IPEEE is March 22, 1995.
The rescheduling of the multi-unit PRA submittal will also force these portions of the IPEEE submittal to be rescheduled to June 26, 1995.
This date has also been discussed with the NRC Project Manager for BFN.
The commitment dates for the Seismic Evaluation Reports, which summarize the results of the A-46 and seismic IPEEE programs for BFN Units 2 and 3
(March 19, 1996) and Unit 1 (prior to restart) remain unchanged.
The current committed internal fires IPEEE submittal dates for BFN Unit 1 (prior to restart) and Unit, 3 (within one hundred twenty days after the first refueling outage following restart) also remain unchanged.
9501260267
'st50119 PDR ADOCK 05000259 p
U.S. Nuclear Regulatory Commission Page 2
January 19, 1995 A summary of the background and previous correspondence on these issues is provided in Enclosure'1.
A summary of the commitments contained in this letter is provided as Enclosure
- 2. If you have any questions, please -contact me at (205) 729-2636.
"Sincer ly Salas Manager of Site, Licensing Enclosures cc:
,see page 3
U.S. Nuclear Regulatory Commission Page 3
January 19, 1995 cc (Enclosures):
Mr. Mark S. Lesser, Section Chief U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 NRC Resident Inspector Browns Ferry Nuclear Plant Route 12, Box 637
- Athens, Alabama 35611 Mr. J.
F. Williams, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852
i
- a "~x r4.
I
ENCLOSURE 1
TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)
UNITS 1~
2 q AND 3 SCHEDULE FOR SUBMITTAL OF THE EXPANDED (MULTI-UNIT)
PROBABZLZSTZC RISK ASSESSMENT (PRA)
AND PORTIONS OF THE INDIVIDUALPLANT EXAMINATION OF EXTERNAL EVENTS (ZPEEE)
I'ACKGROUND A.
Multi-unit PRA Generic Letter 88-20, Individual Plant Examination for Severe Accident Vulnerabilities (Reference 1), dated November 23, 1988, requested all licensees perform the following for each plant:
1 1.
Perform a systematic examination to identify any plant specific vulnerabilities to severe accidents, 2.
Identify and review proposed plant improvements (design changes and changes to operating procedures, maintenance, surveillance,
- training, or staffing) 3.
Decide which of these improvements will be implemented and their schedule, and 4.
Report the results to the Commission.
In response, by letter dated October 30, 1989 (Reference 2),
TVA committed to complete a Level I PRA and containment analysis for Browns Ferry by September 1,
1992.
In August of 1990 (Reference 3),
NRC noted that the three units at BFN share many important safety systems.
NRC expressed a concern with the potential safety implications of shared systems in the various operating modes of the BFN units (e.g., All three units operating, Units 1 and 2 operating with Unit 3 shutdown, etc.).
NRC requested TVA provide:
1.
Dependency tables for Units 1 and 3 similar to that provided for Unit 2, and
2.
Expanded PRAs for Units 1 and 3 that evaluate the entire site as a whole, taking into account the risk significant combinations of unit operational status.
TVA responded to this request on October 12, 1990 (Reference 4).
TVA committed to submit dependency matrices prior to the restart of Unit 3, which assume Units 2 and 3 are operational.
TVA also committed to submit dependency matrices prior to the restart of Unit 1, which assume Units 1, 2, and 3 are operational.
TVA declined to pursue the development of multi-unit PRAs at that time for the following reasons:
~
BFN does not significantly rely on safety systems which are specific to one unit to achieve and maintain safe shutdown of another unit.
The Unit 2 dependency matrices did not identify any instances of cross-train dependencies that would compromise the analyzed safety-related systems.
The subject of unit sharing and interactions was reviewed at the time of the original licensing of BFN.
~
As previously discussed, Generic Letter 88-20 requested licensees perform a single unit PRA. It did not, request licensees of multiple unit sites perform individual PRAs for each plant at a multi-unit site or address the effect of shared systems between units.
In response to Generic Letter 88-20, TVA committed to perform a Level 1
PRA and limited containment analysis, which assumed Unit 2 in operation and Units 1 and 3
shutdown.
In June 1991 (Reference 5),
NRC acknowledged that the performance of these expanded PRAs was not required to fulfilGeneric Letter 88-20.
However, the staff continued to encourage TVA to perform the expanded PRAs for BFN Units 1 and 3.
TVA and NRC met on September 6,
1991 to discuss the NRC's concern (Reference 6).
During this meeting, the staff expressed concerns regarding the number of shared systems at BFN and the control of these systems to ensure availability.
E1-2
In February 1992 (Reference 7),
TVA provided a list of the systems shared between the BFN units and a
description of their shared functions.
TVA reviewed the systems, which are shared between the BFN units, and identified ten systems whose ability to reliably perform their safety function could be challenged due to the impact of system sharing.
The most limiting configuration for the ten shared systems occurs when all three units are in operation.
Loss of offsite power and loss of plant air are the two initiating events that directly result in the shutdown of all three units.
Therefore, TVA committed to perform an expanded PRAg which addresses all three units in operation, that would address the impact of the ten critical shared systems during a loss of offsite power and loss of plant air transients.
TVA stated that it intended to submit a summary report to NRC prior to the restart of Unit 3.
- However, TVA did not consider completion of'this work to be a restart prerequisite.
NRC's review of the TVA approach for addressing multi-unit dependencies was provided in July 1992 (Reference 8).
The Staff agreed that this report was not a prerequisite 'for the restart of Unit 3.
However, the Staff requested TVA to provide formal notification if the completion date should slip beyond the end of 1993.
In response to Generic Letter 88-20, TVA completed and submitted the single unit BFN PRA on September 1,
1992 (Reference 9).
When TVA was initially responding to the hardened vent issue, NRC requested TVA, in an April 1990 teleconference, to incorporate the hardened vent into the PRA.
During development of the initial BFN PRA frontline event trees, it was recognized that the hardened wetwell vent would be implemented for BFN Unit 2 during the Unit 2 Cycle 6 refueling outage.
Since this outage would occur following submittal of the BFN single unit PRA (September 1992),
TVA decided not to model this feature in the initial version of the BFN PRA model.
As discussed in Reference 10, TVA committed to incorporate the hardened vent into the next update of the BFN PRA.
As discussed in Reference 11, TVA committed to summarize the impact of the hardened vent as part of the multi-unit PRA submittal.
El-3
On December 2,
1993 (Reference 12),
TVA provided the Staff with an updated schedule for the submittal of the multi-unit PRA.
At the time of this letter, the Unit 3 design effort had progressed to the point where the multi-unit PRA work could be supported.
Based on the forecasted progression of the Unit 3 design work, TVA provided a January 18, 1995 scheduled submittal date for the multi-unit PRA.
The NRC Safety Evaluation Report (Reference 13) was issued on the single unit BFN PRA on September 28, 1994.
In the Safety Evaluation, the Staff requested TVA to address the feasibility of evaluating the potential benefit of two containment performance improvement items as part of the multi-unit PRA.
B.
EXTERNAL EVENTS PRA On June 28,
- 1991, NRC issued Generic Letter 88-20, Supplement 4 (Reference 14), which requested the systematic examination for plant specific vulnerabilities be expanded to included the consideration of external events.
The five events to be considered are:
1.
Earthquakes, 2.
Internal fires, 3.
High winds, 4.
External floods, and 5.
Transportation and nearby facility accidents.
By letter dated December 20, 1991 (Reference 15),
TVA described the BFN program and schedule for completing the internal fires, high winds, external floods, and transportation and nearby facility accidents portions of the IPEEE.
The schedule for the completion of
~ these portions of the IPEEE was:
1.
BFN will complete the internal fires IPEEE and provide a summary report to NRC prior to the restart of Unit 1, within one hundred twenty days after the restart of Unit 2 from the Cycle 7
refueling outage (March 22, 1995),
and within one hundred twenty days after the restart of Unit 3 from its first refueling outage following restart (Cycle 6 outage)
2.
BFN will complete the high winds, external floods, and transportation and nearby facility accidents IPEEE for all three units and provide a summary report to NRC within one hundred twenty days after the restart of Unit 2 from the Cycle 7 refueling outage (March 22, 1995).
3.
TVA committed to address the seismic portion of the IPEEE within 120 days after the NRC issued a
Supplemental Safety Evaluation Report that resolved Unresolved Safety Issue (USI) A-46, "Verification of Seismic Adequacy of Equipment in Operating Plants".
NRC acceptance of the methods and schedules for the addressed portions of the IPEEE was documented in Reference 16.
TVA provided its initial program and schedule for responding to the seismic portion of the IPEEE on September 21, 1992 (Reference 17).
NRC requested
- additional information on this subject on November 19, 1992 (Reference 18).
TVA responded on January 19, 1993 (Reference 19) and committed to:
1.
Submit a Seismic Evaluation Report, which summarizes the results of the seismic adequacy review (Generic Letter 87-02 and Unresolved Safety Issue A-46) and seismic IPEEE programs for BFN Units 2 and 3, by March 19, 1996.
2.
Submit a Seismic Evaluation Report, which summarizes the results of the seismic adequacy review and seismic IPEEE programs for BFN Unit, 1, before restart.
NRC acceptance of the proposed program and schedule is documented in a Supplemental Safety Evaluation Report, dated March 19, 1993 (Reference 20).
II'EVISED SUBMITTAL SCHEDULES As discussed
- above, the current committed multi-unit PRA submittal date is January 18, 1995.
Due, in part, to a recent request from NRC to expand the scope of the multi-unit PRA, this current commitment date is being rescheduled to April 14, 1995.
This date has been discussed with the NRC Project Manager for BFN.
E1-5
The current committed submittal date for the BFN Unit 2 internal fires and BFN Units 1, 2, and 3 high winds, external floods, and transportation and nearby facility accidents portions of the IPEEE is March 22, 1995.
The rescheduling of the multi-unit PRA submittal will also force these portions of the IPEEE submittal to be rescheduled to June 26, 1995.
This date has also been discussed with the NRC Project Manager for BFN.
The commitment dates for the Seismic Evaluation Reports, which summarize the results of the A-46 and seismic IPEEE programs for BFN Units 2 and 3
(March 19, 1996) and Unit 1 (prior to restart) remain unchanged.
The current committed internal fires IPEEE submittal dates for BFN Unit 1 (prior to restart) and Unit 3 (within one hundred twenty days after the first refueling outage following restart) also remain unchanged.
El-6
III REFERENCES 1 ~
2 ~
NRC letter to All Licensees Holding Operating Licenses and Construction Permits, dated November 23, 1988, Individual Plant Examination for Severe Accident Vulnerabilities 10 CFR
$50.54(f)
TVA letter to NRC, dated October 30,
- 1989, Proposed Program in Response to Generic Letter 88-20 Individual Plant Examination (IPE) for Severe Accident Vulnerabilities 3.
NRC letter to TVA, dated August 13,
- 1990, PRA Concerns Regarding Operation of Browns Ferry, Units 1
and 3
4 ~
5.
6.
7.
8.
TVA letter to NRC, dated October 12,
- 1990, PRA Concerns Regarding Operation of Browns Ferry, Units 1
and 3
NRC letter to TVA, dated June 28, 1991, Individual Plant Examination for Severe Accident Vulnerabilities (Generic Letter 88-20),
Browns Ferry Nuclear Plant, Units 1, 2, and 3
NRC letter to TVA, dated November 1,
- 1991, Summary of the September 6,
1991 Meeting with TVA Regarding the Appropriate Methodology for Conduction Individual Plant Examinations (IPE) at Multi-Unit Sites TVA letter to NRC, dated February 7,
- 1992, Expanded Probabilistic Risk Assessment (PRA) Considering Operation of Browns Ferry, Units 1 and 3
NRC letter to TVA, dated July 22,
- 1992, TVA Approach for Addressing Inter-Unit Dependencies as part of the Individual Plant Examination for the Browns Ferry Nuclear Plant 9.
10.
TVA letter to NRC, dated September 1,
- 1992,
Response
to Generic Letter (GL) 88-20 "Individual Plant Examination for Severe Accident Vulnerabilities 10 CFR 50.54(f)"
TVA letter to NRC, dated May 1, 1990, Probabilistic Risk Assessment (PRA) and Emergency Operating Procedure (EOP)
El-7
12.
13
~
14.
15.
16.
TVA letter to NRC, dated December 23,
- 1993,
Response
to Request for Additional Information Regarding the Individual Plant Examination (IPE)
TVA letter to NRC, dated December 2,
- 1993, Expanded Probabilistic Risk Assessment (PRA)
NRC letter to TVA, dated September 28,
- 1994, Individual Plant Examination Submittal for Internal Events NRC letter to All Licensees Holding Operating Licenses and Construction Permits for Nuclear Power
- Reactors, dated June 28, 1991, Individual Plant Examination of External Events (IPEEE) for Severe Accident Vulnerabilities 10 CFR 50.54(f)
(Generic Letter No. 88-20, Supplement 4)
TVA letter to NRC, dated December 20,
- 1991, Individual Plant Examination of External Events (IPEEE) for Severe Accident Vulnerabilities (Generic Letter 88-20, Supplement 4)
NRC letter to TVA, dated July 2,
- 1992, Review of
Response
to Generic Letter 88-20, Supplement No.
4 Individual Plant Examinations for External Events 17
~
18.
19.
20.
TVA letter to NRC, dated September 21,
- 1992, Supplement 1 to Generic Letter 87-02, Verification of Seismic Adequacy of Mechanical and Electrical Equipment in Operating Reactors, Unresolved Safety Issue (USI) A-46 and Supplement 4 to Generic Letter 88-20, Individual Plant Examination of External Events (IPEEE) for Severe Accident Vulnerabilities NRC letter to TVA, dated November 19,
- 1992, Generic Letter 87-02, Supplement 1 Response TVA letter to NRC, dated January 19,
- 1993, Generic Letter (GL) 87-02, Supplement 1,
120-Day Response, Request for Additional Information NRC letter to TVA, dated March 19,
- 1993, Generic Letter 87-02, Supplement 1 Response E1-8
ENCLOSURE 2
TENNESSEE VALLEY AUTHORZTY BROWNS FERRY NUCLEAR PLANT (BFN)
UNITS,1~
2~
AND 3 SCHEDULE FOR SUBMITTAL OF THE EXPANDED (MULTI-UNIT)
PROBABILZSTIC RISK ASSESSMENT (PRA)
AND PORTIONS OF THE INDIVIDUALPLANT EXAMINATION OF EXTERNAL EVENTS (ZPEEE)
SUMMARY
OF COMMITMENTS 1.
The multi-unit Probabilistic Risk Assessment will be submitted by April 14, 1995.
2.
The Unit 2 internal fires and Units 1, 2,
and 3 high winds, external floods, and transportation and nearby facility accidents portions of the Individual Plant Examination of External Events will be submitted by June 26, 1995.