ML18037A878
| ML18037A878 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 05/06/1994 |
| From: | Dante Johnson, Machon R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| LER-94-002-02, LER-94-2-2, NUDOCS 9405180008 | |
| Download: ML18037A878 (26) | |
Text
ACCELERATED DI UTION DEMONSTTION SYSTEM.
2 REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:9405180008 DOC.DATE: 94/05/06 NOTARIZED: NO DOCKET g FACIL:50-260 Browns Ferry Nuclear Power Station, Unit 2, Tennessee 05000260 AUTH. NAME AUTHOR AFFILIATION JOHNSON,D.A. Tennessee Valley Authority MACHON,R.D. Tennessee Valley Authority RECIP.NAME RECIPIENT AFFILIATION R
SUBJECT:
LER 94-002-00:on 940412,noncompliance w/10CFR50,App R resulted in plant being outside design basis. Caused by personnel error.C/As:engineering dept personnel will review D circumstances that led to events.W/940506 ltr.
DIE TRIBUTIQN GQDE: IE22T GQPIE$ REGEIUED:LTR I ENGL ( sIzE: I TITLE: 50.73/50.9 Licensee Event Report (LER), Inciden&Rpt, etc.
NOTES:
RECIPIENT COPIES RECIPIENT COPIES D ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-4-PD 1 1 TRIMBLE,D 1 1 D
INTERNAL- ACRS 1 1 AEOD/DOA 1 1 AEOD/DS P/TPAB 1 1 AEOD/ROAB/DSP 2 2 NRR/DE/EELB 1 1 NRR/DE/EMEB 1 1 NRR/DORS/OEAB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRIL/RPEB 1 1 NRR/DRSS/PRPB 2 2 NRR/&SABA/SPLB 1 1 NRR/DSSA/SRXB 1 1 REG FIL'E 02 1 1 RES/DSIR/EIB 1 1 GN2 FILE 01 1 1 EXTERNAL EGGG BRYCE i J ~ H 2 2 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHY,G.A 1 1 NSIC POORE,W. 1 1 NUDOCS FULL TXT 1 1 D
A D
D NOTE TO ALL "RIDS" RECIPIENTS:
S PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROiVI DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!
FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 28 ENCL 28
0 Tennessee Vaitey Authonty. Post Offce Box 2000, Decatur, Atabama 35609.2000 R. D. (Rick) Machon Vice President.'Browns Ferry Huctear Rant gg 06 199$
U.S. Nuclear Regulatory Commission 10 CFR 50.73 ATTN: Document Control Desk Washington, D.C. 20555
Dear Sir:
BROWNS FERRY NUCLEAR PLANT (BFN) - UNIT 2 - DOCKET NO+ 50-260 FACILITY OPERATING LICENSE DPR-52 LICENSEE EVENT REPORT (LER) 50 260/94002 The enclosed LER provides details concerning two conditions involving noncompliance with the requirements of 10 CFR Part 50 Appendix R. These conditions were caused by individual failures to correctly interpret/implement the applicable requirements used during the original development of the Unit 2 Appendix R Program.
This LER is being submitted in accordance with 10 CFR 50.73(a) (2) (ii) (B) .
Sincerely, R. D. chon Site Vice President PAB 1E-BFN Enclosure cc: See page 2
'7405180008 st40506 gP, PDR ADOCK 05000260 S PDR
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U.S. Nuclear Regulatory Commission if@0 6 1994 Enclosure cc (Enclosure):
INPO Records Center Suite 1500 1100 Circle 75 Parkway Atlanta, Georgia 30339 Paul Krippner American Nuclear Insurers Town Center, Suite 300S 29 South Main Street West Hartford, Connecticut 06107 NRC Resident Inspector Browns Ferry Nuclear Plant Route 12, Box 637 Athens, Alabama 35611 Regional Administrator U.S. Nuclear Regulatory Commission Region 101 II Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. J. F. Williams, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Mr. D. C. Trimble, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852
II 0 NRC FORH 366 U.S NUCLEAR REGULATORY CQNISSI ON APPROVED BY (NQt NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPOHSE TO COHPLY WITH THIS INFORHATION COLLECTION REOJEST: 50.0 HRS.
LZCENSEE EVENT REPORT (LER) FORWARD COMHEHTS REGARDING BURDEN EST IHATE TO THE IHFORHATION AND RECORDS MANAGEMENT BRANCH (HNBB 7714), U.S. NUCLEAR REGULATORY COMMISSIONS (See reverse for required number of digits/characters for each block) 'WASHINGTON, DC 20555-0001 AND TO THE PAPERWORK REDUCTION PROJECT (3140-0104), OFFICE OF MANAGEMENT AND BUDGET 'WASHINGTON DC 20503.
FACILITY NAME (1) DOCKET NEER (2) PAGE (3)
Browns Ferr Nuclear Plant BFN Unit 2 05000260 1 OF 10 TITLE (4) Noncompliance with 10 CFR 50 Appendix R Results in Plant Being Outside Its Design Basis EVENT DATE 5 LER NINBER 6 REPORT DATE 7 OTHER FACILITIES INVOLVED 8 SEQUENTIAL REVISION FACILITY NAHE DOCKET NUHBER MONTH DAY YEAR YEAR MONTH DAY YEAR NUHBER NUHBER FACILITY NAHE DOCKET NUHBER 04 12 94 94 002 00 05 06 OPERATING THIS REPORT IS SUBHITTED PURSUANT TO THE REOUIREMENTS OF 10 CFR = Check one or more 11 H(X)E (9)
N 20.402(b) 20.405(c) 50.73(a)(2)(iv) 73.71(b)
POWER 20.405(a)(1)(i) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c) 100 50.36(c)(2) 50.73(a)(2)(vii)
LEVEL (10) 20.405(a)(1)(ii) OTHER 20.405(a)(1)(iii) 50.73(a)(2)(i) 50.73(a)(2)(viii)(A) (Specify in 20 '05(a)(1)(iv) 50.73(a)(2)(ii) 50.73(a)(2)(viii)(B) Abstract below and in Text, 20 '05(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x) NRC Form 366A LICENSEE CONTACT FOR THIS LER 12 HAHE TELEPHONE NUMBER (Include Area Code)
D. Alan Johnson, Licensing Engineer (205)729-3714 C(NPLETE ONE LINE FOR EACH C(NPONENT FAILURE DESCRIBED IN THIS REPORT 13 SYS REPORTABLE CAUSE COMPONENT MANUFACTURER CAUSE SYSTEH COHPONENT MANUFACTURER TEH TO NPRDS SUPPLEMENTAL REPORT EXPECTED 14 MONTH DAY YEAR EXPECTED YES SUBIIISSION X NO (lf yes, complete EXPECTED SUBHISSION DATE). DATE (15)
ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten Lines) (16)
On April 12, 1994, Browns Ferry Unit 2 was operating at approximately 100% power when TVA concluded that two errors in the Unit 2 Appendix R Program involving noncompliance with 10 CFR Part 50 Appendix R requirements were reportable as conditions outside the desi.gn basis of the plant. The errors were identified by TVA on October 28, 1993, and December 29, 1993, and initially determined to be not reportable. The first error involves power supply cables to redundant reactor water cleanup system valves being located in the same fire zones. The second error involves an associated circuit concern wherein the power supply cable to a spare Unit 1 raw cooling water pump was not adequately separated electrically from a Unit 2 4160-volt shutdown board needed for safe shutdown.
Both errors were identified during the development of the Unit 3 Appendix R Program.
The errors resulted from individual failures to correctly interpret/implement the applicable requirements of the calculations and/or design criteria used during the original development of the Unit 2 Appendix R Program. The program was developed from 1985 through Unit 2 restart in May 1991.
Upon discovery of these events, the appropriate fire watches were posted. Modificati.ons have been or will be implemented to correct these deficiencies. To address the root cause, the affected engineering department personnel will review the circumstances that led to these events.
A previous event concerning noncompliance with 'Appendix R was reported in LER 259/91-008.
NRC FORH 366 (5-92)
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NRC FORH 366A U.S. NUCLEAR REGULATORY CQBIISSION APPROVED BY (BIB NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPONSE TO COHPLY llITH THIS INFORHATION COLLECTION REQUEST: 50.0 HRS. FORNARD COHHENTS REGARDING BURDEN ESTIHATE TO THE INFORHATION AND RECORDS HANAGEHENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COHHISSION, LICENSEE EVENT REPORT llASHINGTON, DC 20555-0001, AND TO THE PAPERNORK REDUCTIOH TEXT CONTINUATZON PROJECT (3150-0104), OFFICE OF HANAGEHENT AND BUDGET, llASNINGTON DC 20503 FACILITY NAHE (1) DOCKET'IMBER (2) LER NIBGIER (6) PAGE (3)
YEAR SEQUENTIAL REVISION NUHBER NUHBER Browns Ferry Unit 2 05000260 94 002 00 2 of 10 TEXT lf more s sce is r ired use sdditionsI co ies of NRC Form 366A (17)
Z~ PLANT CONDITIONS On April 12, 1994, Unit 2 was at 100 percent power.
II DESCRIPTION OF EVENT A. Event On April 12, 1994, TVA concluded that two conditions involving noncompliance with 10 CFR Part 50 Appendix R, Criterion IZI.G.2 were reportable as conditions outside the design basis of the plant (10 CFR 50.72 (b)(1)(ii)(B) and 10 CFR 50.73 (a)(2)(ii)(B)).
These conditions were identified on October 28, 1993, and December 29, 1993. TVA initially evaluated these incidents and determined that they were not reportable pursuant to the requirements of 10 CFR 50.72 and 50.73 (Reference TVA letter dated April 13, 1994, "NRC Inspection Report 50-259, 50-260, and 50-296/94-01 Reply to Notice of Violation").
10 CFR 50 Appendix R, Criterion IZZ.G.2 requires, "where cables or equipment, including associated non-safety circuits that could prevent operation or cause maloperation due to hot shorts, open circuits, or shorts to ground, of redundant trains of systems necessary to achieve and maintain hot shutdown conditions are located within the same fire area outside of primary containment,
[an acceptable] means of ensuring that one of the. redundant trains is free of fire damage shall be provided." This requirement was not met for the following two examples:
On October 28, 1993, TVA discovered that power supply cables to redundant Reactor Water Cleanup (RWCU)[CE) system primary containment isolation valves [ISV] are located within twenty feet of one another in Fire Zone 2-4 and the cable spreading room portion of Fire Area 16. Fire Zone 2-4 consists of the reactor building [NG] Elevation 593. Fire Area 16 consists of the cable spreading room and the control room [NA).. The cables are not adequately protected by an appropriate fire barrier.
The cables supply power to the RWCU system inboard and outboard primary containment isolation valves (FCV 69-1 and FCV 69-2).
In order to meet BFN Unit 2 Appendix R safe shutdown requirements, one or both of the valves need to be shut to prevent the potential for a loss of reactor coolant inventory.
On December 29, 1993, TVA discovered that in situations when Raw Cooling Water (RCW)[KI) pump 1D [P) (a spare pump for Unit 2 operation) is being used to support Unit 2 operation and its power supply breaker is closed, associated circuit concerns exist. RCW Pump 1D's power supply cable was not adequately
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HRC FORM 366A U.S. IRICLEAR REGULATORY CQOIISSION APPROVED BY CWB NO. 3150-0104 (5-92) EXP I RES 5/3'I/95 ESTINATED BURDEN PER RESPOHSE TO COHPLY lllTH THIS INFORHATION COLLECTIOH REQUEST: 50.0 HRS. FORlJARD COHHEHTS REGARDING BURDEN ESTINATE TO THE INFORHATIOH AND RECORDS NANAGEHENT BRANCH (NHBB 7714) ~ U.S. NUCLEAR REGULATORY COHHISS ION, LICENSEE EVENT REPORT MASHINGTOH, DC 20555-0001, AND TO THE PAPERIJORK REDUCTION TEXT CONTINUATION PROJECT (3150-0104), OFFICE OF NANAGEHENT AND BUDGET,
'WASHINGTON DC 20503 FACILITY NHK (1) DOCKET NINSER (2) LER NI&BER (6) PAGE (3)
'YEAR SEQUENTIAL REVI SION NUMBER NUHBER Browns Ferry Unit 2 05000260 94 002 00 3 of 10 TEXT lf morc s ce is r ired use sdditlonet co ies of NRC Form 366A (17) separated electrically from Unit 1/2 4160-volt Shutdown Board "A" [EB]. The shutdown board is required to meet Unit 2 Appendix R safe shutdown requirements. Additionally, the RCW pump 1D's power supply cable is routed in common enclosures that house cables to other fire safe shutdown equipment needed to support Unit 2. The common enclosure areas are located in Fire Areas 1 (reactoL building) 5 (4160-volt shutdown board g
room "A" [NA)), 16 (cable spreading room and control room), and 25 (turbine building [NM), cable tunnel, and intake pumping station [NN]).
A failure of RCW pump 1D's trip circuit control cable, combined with a fault in its power cable, could cause 1) a loss of power to Unit 1/2 4160-volt Shutdown Board "A," or 2) a malfunction of a cable supplying power to other fire safe shutdown equipment.
These conditions have existed since Unit 2 returned to B.
operation in May 1991.
Ino erable Structures Com onents the Events
'r S stems that Contributed to None C. Dates and A roximate Times of Ma or Occurrencesi October 28, 1993, and December 29, 1993: Noncompliance with Appendix R requirements discussed in Section II.A identified.
April 12, 1994( TVA concluded that the conditions were reportable, and Emergency Notification System notification made per 10 CFR 50.72 at approximately 1339 (CDST).
D. Other S stems or Seconda Functions Affected:
None E. Method of Discove The conditions involving noncompliance with the requirements of Appendix R were identified during the development of the Unit 3 Appendix R Program. In each case, engineers [utility and non-utility, non-licensed) would identify a situation in Unit 3 that required action be taken to ensure compliance with Appendix R
0 if' NRC FORM 366A U.S. IN)CLEAR REGULATORY CWISSION APPROVED BY (HCB NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY MITH THIS INFORMATION COLLECT ION REQUEST: 50.0 HRS. FORIIARD COMMEHTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION g LICENSEE EVENT REPORT NASH IHGTON ~ DC 20555-0001 ~ AND TO THE PAPERUORK REDUCTION TEXT CONTINUATION PROJECT (3150-0104), OFFICE OF MAHAGEMENT AND BUDGET, NASHINGTOH DC 20503 FACILITY NAlK C1) DOCKET NIMBER C2) LER NINBER (6) PAGE C3)
YEAR SEQUENTIAL REVISION NUMBER NUMBER Browns Ferry Unit 2 05000260 94 002 00 4 of .10 TEXT If more s ce is r uired use additionsI co ies of NRC Form 366A (17)
(e.g., relocate cables, install a would fire barrier). Since Units 2 and 3 are similar, the engineers review the Unit 2 program to determine what had been done to resolve a similar situation if it had existed. While reviewing the Unit 2 program, the engineers identified that the requirements of Appendix R had not been met.
crater Actions:
None.
- 0. Safet S stem Res onsest None.
III ~ CAUSE OF THE EVENT A. Immediate Cause:
Noncompliance with 10 CFR Part 50 Appendix R.
B. Root Cause:
This event resulted from individual failures to correctly interpret/implement the applicable requirements of the calculations and/or design criteria used during the original development of the Unit 2 Appendix R Program. The Unit 2 program was developed from 1985 through Unit 2 restart in May 1991. The specifics of the two examples are discussed below:
Reactor Water Cleanu S stem Valve Power Cables Too Close The individuals involved in preparing the Unit 2 Appendix R required equipment list did not properly interpret a calculation used as input (cognitive personnel error). The input calculation clearly noted that RWCU isolation was not available for fires in Fire Zone 2-4 or Fire Area 16. The individual apparently missed this information in the calculation.
Raw Coolin Water Pum 1D Associated Circuit Concern The individuals involved in preparing the Unit 2 associated circuit analysis did not properly evaluate the potential impact that a Unit 1 spare RCW pump had on Unit 2 (cognitive personnel error). The individuals performing the Unit 2 analysis apparently did not recognize that associated circuit and common enclosure concerns exist when the RCW Pump 1D supply breaker is closed.
0 NRC FORH 366A U.S. IN)CLEAR REGUULTORY C(NNI I SS ION APPROVED BY CNB NO. 3150-0104 (5-92) EXPIRES 5 /31/95 ESTIHATED BURDEN PER RESPONSE TO COHPLY MITH THIS IHFORHATION COLLECTION REQUEST: 50.0 HRS. FORMARD COHHEHTS REGARDING BURDEN EST IHATE TO THE INFORHATION AND RECORDS HANAGEHENT LZCENSEE EVENT REPORT BRANCH (HNBB 7714), I U.S. NUCLEAR REGULATORY COHHI SS ON/
MASHINGTON, DC 20555-0001, AND TO THE PAPERMORK REDUCTION TEXT CONTZNUATZON PROJECT (3150-0104) ~ OFFICE OF HANAGEHENT AND BUDGET ~
MASHINGTON DC 20503 FACILITY NAHE (1) DOCKET HINIBER (2) LER NINIBER (6) PAGE C3)
YEAR SEQUENTIAL REVISION NUHBER NUHBER Browns Ferry Unit 2 05000260 94 002 00 5 of 10 TEXT tf more s ce is r ired use additional co les of NRC Form 366A (17)
C. Contributin Factorss None.
ZV ANALYSZS OF THE EVENT For each situation, a complex and unlikely series of circumstances and/or failures must occur for a situation to exist that would adversely impact the ability to achieve and maintain safe shutdown.
Reactor Water Cleanu S stem Valve Power Cables Too Close The BFN Unit 2 safe shutdown program requires that one or both of the RWCU primary containment isolation valves (FCV 69-,1 or FCV 69-2) be shut. These valves are shut to prevent high temperature reactor coolant flow into low temperature RWCU system piping downstream of the non-regenerative heat exchanger [HX]. The low temperature RWCU system piping is not analyzed for the high temperatures associated coolant with the reactor coolant system. Thus, if high temperature reactor flows into the RWCU low temperature piping, the piping or piping system components are presumed to potentially fail.
TVA considers that it is not credible to assume that a situation could occur that would cause a component in the low temperature piping to if fail a fire were to occur in Fire Zone 2-4 or Fire Area 16. Because of the fire protection features that exist in these fire areas, highly unlikely that a design basis fire could occur. Also, if it a
is design basis fire were.to occur, multiple failures and circumstances would be necessary in order to affect safe shutdown.
Fire Zone 2-4 is provided with a general area coverage preaction sprinkler system and a detection system. The combustible loading is approximately 45,000 Btu/ft with a fire severity of approximately 34 minutes.
Fire Area 16 is provided with partial coverage. The cable spreading room portion of Fire Area 16 is provided with an area wide preaction sprinkler system and detection system. The main control room portion of Fire Area 16 is provided with an area wide detection system. The main control room is not provided with a suppression system but it is continuously manned. The combustible loading in the main control room is approximately 39,000 Btu/ft with a fire severity of approximately 30 minutes. The combustible loading in the cable spreading rooms is approximately 126,000 Btu/ft~ with a fire severity of approximately 95 minutes. The combustible load in the cable spreading room is due mainly to the cables present and most of the cables are coated with flamastic.
NRC FORN 366A U S. NUCLEAR REGULATORY CQBIISSION APPROVED BY (H(B NO 3150-0104 (5-92) EXPIRES 5/31/95 ESTINATED BURDEN PER RESPONSE TO COHPLY llITH THIS INFORMATION COLLECTIOH REQUEST: 50.0 HRS. FORMARD COMMENTS REGARDING BURDEN EST IHATE TO THE IHFORNATIOH AND RECORDS NANAGENEHT BRANCH (HNBB 7714), U.S. NUCLEAR REGULATORY CONHISSION p LICENSEE 'EVENT REPORT LIASHINGTOH, DC 20555-0001 ~ AND TO THE PAPERNORK REDUCTION TEXT CONTINUATION PROJECt (3150 0104), OFFICE OF NANAGENEHT AND BUDGET, NASHINGTON DC 20503 FACILITY NAHE (1) DOCKET NINBER (2) LER NINBER (6) PAGE (3)
YEAR SEQUENTIAL REVISION HUNGER HUHBER Browns Ferry Unit 2 05000260 94 002 00 6 of 10 TEXT If more s ce is r fred use additional co les of MRC Form 366A <<17)
Administrative procedures are in place that restrict the performance of hot work (e.g., welding, cutting, etc.) during plant operation and the storage of transient combustibles. Thus, there should be insufficient external combustible sources to cause a significant exposure fire.
With the detection and suppression systems available in the affected fire areas, the flamastic coating on the cables, lack of external combustible sources in the cable spreading room, and the relatively light combustible loading, the likelihood of a fire that would disable or spuriously operate the RWCU valves and/or pump is extremely unlikely.
If a fire were to occur, TVA considers that proper circumstances to exist that would cause a loss of safety it is not credible for the function. Reactor coolant flowing into the low temperature portion of the RWCU system is normally cooled by the Reactor Building Closed Cooling Water System (RBCCW) [CC). This system is presumed to be unavailable during a design basis fire. Water is circulated in the RWCU system using the RWCU recirculation pump [P]. There are two flow paths having the potential to cause RWCU pipe overheating were to occur in one of these areas. They are 1) the normal if a fire recirculation path back to the feedwater system, or 2) the blowdown path to the main condenser or the radwaste system. In order for a fire to cause a loss of reactor coolant, the following must occur:
The fire must damage both control power cables so that neither primary containment isolation valve can be shut (shutting these valves is an action required to be performed soon after a fire occurs) or it must cause both valves to spuriously open.
For the first flowpath, in addition to both primary containment isolation valves being open, the fire must incapacitate the ability to secure the RWCU pump and shut or spuriously open another RWCU valve that could be used to stop flow.
/
For the second flowpath, in addition to both primary containment isolation valves being open, the fire must incapacitate the ability to shut or spuriously open three other RWCU valves that could be used to stop flow.
Raw Coolin Water Pum 1D Associated Circuit Concern RCW Pump 1D is powered from the 4160-volt Shutdown Board A. The pump is not needed for safe shutdown; however, 4160-volt Shutdown Board A supplies other fire safe shutdown components that are needed were to occur in Fire Areas 16 and 25. Also, the pump's power supply if a fire cable and trip circuit control cable are routed in enclosures common to other fire safe shutdown equipment in Fire Areas 1, 5, 16, and 25.
Damage to the pump's trip circuit control cable combined with a fault in its power supply cable could cause 1) a loss of 4160-volt Shutdown
NRC FORN 366A U S. INCLEAR REGULATORY CQKISSION APPROVED BY (%8 NO 3150-0104 (5.92) EXPIRES 5/31/95 ESTINATED BURDEN PER RESPONSE TO CONPLY IIITH THIS INFORHATION COLLECTIOH REQUEST: 50.0 HRS. FORllARD CNNEHTS REGARDING BURDEN EST INATE TO THE INFORHATION AND RECORDS HANAGENENT BRANCH (NNBB 7714), U.S. NUCLEAR REGULATORY COHHISSION ~
LICENSEE EVENT REPORT llASHINGTOH, DC 20555-0001 ~ AND TO THE PAPERINRK REDUCTION TEXT CONTINUATION PROJECT (3150-0104), OFFICE OF NANAGEHENT AND BUDGET, NASHINGTON DC 20503 FACILITY NANE (1) DOCKET NNIBER (2) LER NNSER (6) PAGE (3)
YEAR SEQUENTIAL REVISION NUNBER NUHBER Browns Ferry Unit 2 05000260 94 002 00 7 of 10 TEXT If more s ce is r tred use edditionet co tes of NRC Form 366A <<17)
Board A, or 2) the loss of a cable supplying power to other fire safe shutdown equipment routed in the same enclosure as the power feed cable to RCW pump 1D. TVA considers that it is not credible to assume that a situation could occur that would adversely impact the ability to achieve and maintain safe shutdown. First, RCW Pump 1D is a spare pump and is not normally used to support Unit 2 operation. It is highly unlikely that a fire would occur during the limited periods of time that RCW Pump 1D is being used. Second, because of the fire protection features that exist in the fire areas of concern, it is highly unlikely that a design basis fire could occur. Third, if a design basis fire were to occur, multiple failures and circumstances would be necessary to affect safe shutdown.
If a fire were to occur in Fire Area 1, 4160-volt Shutdown Board A is not rectuired for safe shutdown. Therefore, loss of the shutdown board is not a concern. There is no common enclosure concern since there are no locations where the RCW pump 1D cables coexist with other safe shutdown equipment needed for a fire in Fire Area l.
In Fire Area 5, 4160-volt Shutdown Board A and RCW Pump 1D's power supply cables are located together in the same fire area. Thus, associated circuit concerns do not exist.
In Fire Area 25 associated circuit concerns do not exist since the potential for a cable to cable short that could cause a loss of the trip function does not exist. Thus, the pump can easily be isolated from the shutdown board.
For a fire in Fire Area 16, the trip circuit cable and the control cables for RCW pump 1D are routed in cable tray RT. The power feed cable to RCW pump 1D is routed in cable tray BA. During a fire, the cables in cable tray RT could potentially interact and cause the loss of the trip function to the pump breaker. This loss of the trip function is only a concern if the power cable in cable tray BA is also damaged by the fire. However, this is unlikely since the section of cable tray RT where the control cables are located is approximately 40 feet from cable tray BA where the power cable is located. A discussion of the fire protection features in Fire Area 16 is described above.
Due to these fire protection features, the likelihood of a fire that would damage both the control and power cable is extremely unlikely.
RCW Pump 1D's trip circuit cable is also routed in Panel 9-20 in the main control room portion of Fire Area 16. Therefore, a potential hot short from other cables in this panel could occur. A fire in this panel will be detected promptly since there are smoke detectors located in the panel and the Main Control Room is continuously manned. If a fire were to occur, it is highly unlikely that the trip circuit cable in the Main Control Room will be damaged in conjunction with damage to the power feed cable that is located in the Cable Spreading Room.
4l ig)
NRC FORM 366A U S IRICLEAR REGULATORY CQNISSIOH APPROVED BY (NIB NO 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COHPLY WITH THIS INFORHATION COLLECTION REQUEST: 50.0 NRS. FORWARD COMMENTS REGARDING BURDEH ESTIMATE TO THE INFORHATION AND RECORDS MANAGEHENT BRANCH (HNBB 7714), U.S. NUCLEAR REGULATORY COHHISSION, LICENSEE EVENT REPORT WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION TEXT CONTINUATION PROJECT (3150-0104), OFFICE OF MANAGEMENT AND BUDGETS WASHINGTON DC 20503 FACILITY IOUS (1) DOCKET IRNBER (2) LER NWBER (6) PAGE (3)
TEAR SEQUENTIAL REVISION NUMBER NUMBER Browns Ferry Unit 2 05000260 94 002 00 S of 10 TEXT If more s ce is r uired use additional co ies of NRC Form 366A (17)
Based on the above, TVA concludes that these conditions did not jeopardize the public health and safety.
V. CORRECTIVE ACTIONS Ao Immediate Corrective Actions:
A Problem Evaluation Report (PER) was initiated for each situation in accordance with the TVA Corrective Action Program.
Upon discovery of each event, TVA establi.shed the appropriate fire watches in accordance with the BFN Unit 2 Appendix R Safe Shutdown Program.
B~ Corrective Actions to Prevent Recurrence!
Reactor Mater Cleanu S stem Valve Power Cables Too Close TVA will implement a modification to ensure the isolation capabili.ty of the RWCU system per the Unit 2 Appendix R program requirements (i.e., Fire Zone 2-4 and Fire Area 16). Components needed to perform the Unit 2 modification to the RWCU system are currently not available and will require a long lead time to procure. Therefore, TVA will complete this modification prior to the Unit 2 cycle 9 operation. Once the components become available, TVA will make every effort to complete the modification at the earliest opportunity.
TVA will also ensure the isolation capability of the RWCU system for Units 1 and 3 per the Appendix R Programs requirements. The appropriate modifications will be completed prior to each uni.t's restart.
Raw Coolin Water Pum 1D Associated Circuit Concern TVA performed a revi.ew of the loads supplied by the 4160-volt shutdown boards. Based on this review, TVA determined that the problem related to RCW Pump 1D was the only concern for Unit 2 operation. A similar problem was identified in Unit 3 involving RCW Pump 3D. This was the only concern identified in Unit 3. No similar concerns were identified related to the operation of Uni.t
- 1. The errors involving the operational impact of spare pumps are limited to the RCW pumps with no other similar problems identified.
A modification has been implemented in Unit 2 to prevent the loss of trip function for a postulated fault on the RCW pump 1D trip circuit control cable. No modification is required for Unit 1. A modification will be implemented in Unit 3 to prevent the loss of
41 NRC FORN 366A U.S. INCLEAR REGULATORY CQHISSIOH APPROVED BY CHCB HO 3150-0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPONSE TO CONPLY IIITH THIS INFORNATION COLLECTION REQUEST: 50.0 HRS. FORIJARD COO!ENTS REGARDING BURDEN EST IHATE TO THE INFORNATION AND RECORDS HAHAGENENT BRANCH (NNBB 7714), U.S. NUCLEAR REGULATORY CONHI SS ION, LICENSEE EVENT REPORT NASHINGTON, DC 20555-0001, AND TO THE PAPERNORK REDUCTION TEXT CONTINUATION PROJECT (3150-0104), OFFICE OF NANAGEHENT AND BUDGET, UASHINGTOH DC 20503 FACILITY RANE C1) DOCKET HIHIBER C2) LER HNIBER C6) PAGE (3)
YEAR SEQUEHI'IAL REVISION NUHBER NUMBER Browne Ferry Unit 2 05000260 002 00 9 of 10 TEXT lf more s sce is r ired use additional co tes of NRC Form 366A (17) trip function for a postulated fault on the RCW pump 3D trip circuit control cable. The appropriate modifications will be completed prior to Unit 3's restart.
I fo atio to ddress Ge eric As ects The examples cited above are two of the five errors in the Unit 2 program discovered by TVA during development of Unit 3 Appendix R Program. Development of the Unit 3 program has required more than 130,000 man-hours. Each of the errors was found when 1) individuals developing the Unit 3 program identified a deficiency (e.g., cables too close together, associated circuit concern) and
- 2) determined if a similar situation had existed in Unit 2. As an indirect result, validation of the Unit 2 program occurred.
TVA has reviewed the five errors and has determined that each error was a different type of mistake made during the preparation of the Unit 2 Appendix R calculations. Each error represents an example of an individual or individuals making a cognitive error while performing an assigned task. TVA's review did not indicate any consistent trend or methodology problem.
TVA reviewed the procedural requirements for calculation preparation, review, and approval. TVA determined that present procedural controls are adequate. Based on this review and the completeness of the Unit 2 program "revalidation,"
judgement that this violation does not represent a programmatic it is TVA's Appendix R concern.
While, the five errors may not have a common thread, they provide valuable "lessons learned." Therefore, TVA will conduct training with the appropriate Nuclear Engineering managers and engineers.
The training will consist of a discussion about the five errors, the cause of the errors, the importance of attention to detail, and the procedural requirements for calculation preparation.
Additionally, the training will emphasize that the circumstances that led to this violation were self-identified during TVA's development of the Unit 3 Appendix R program. Engineering personnel will be encouraged to utilize the same comparison techniques that led to the identification of this issue.
VI ~ ADDITIONAL INFORMATION Ao Failed Com onents:
None
0 NRC FORM 366A U.S IRJCLEAR REGULATORY CQBIISSION APPROVED BY QRI NO 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO CQIPLY MITH THIS INFORMATION COLLECT ION REOUEST: 50.0 HRS. FORWARD COMHEHTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, LICENSEE EVENT REPORT NASHIHGTOH, DC 20555-0001 'ND TO THE PAPERIJORK REDUCTION TEXT CONTZNUATZON PROJECT (3150-0104), OFFICE OF MANAGEMEHT AND BUDGET, MASHINGTOH DC 20503 FACILITY NAME (1) IXXXET NWBER C2) LER NQCBER C6) PAGE C3)
TEAR SEQUENTIAL REVISI OH NUMBER NUMBER Browns Ferry Unit 2 05000260 94 002 00 10 of 10 TEXT If more s ce is r ired use edditionsi co ies of NRC Form 366A (17)
B. Previous LERs on Similar Eventsf Zn LER 259/91-008, TVA reported a noncompliance with Appendix R.
Specifically, this event concerned the discovery that fire wrap had been removed from several )unction boxes and a pull box; and that a fire watch had not been established per the Technical Specification requirements at that time. The circumstances associated with this LER (i.e.,94-002) are different in that the affected components never had the required fire barrier or separation.
VII'OMMITMENTS
- 1. The Unit 1 modification to ensure the RWCU system isolation capability will be completed prior to Unit 1 restart.
- 2. The Unit 2 modifications to ensure the RWCU system isolation capability will be completed prior to the Unit 2 cycle 9 operation.
- 3. The Unit 3 modifications to ensure the RWCU system isolation capability and RCW Pump 1D isolation will be completed prior to Unit 3 Restart.
- 4. Training of the appropriate Nuclear Engineering managers and engineers will be completed by May 16, 1994.
Energy Industry Identification System (EZZS) system and component codes are identified in the text with brackets (e.g., [XX]).
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