ML17289B167

LER 88-031-01:on 880902,determined That Due to Single Failure CR HVAC Sys Could Operate in Recirculation Mode. Caused by Lack of Communication Between Ae Design Groups.Cr HVAC Recirculation Mode of Operation analyzed.W/930212 Ltr

ML17289B167
Person / Time
Site:	Columbia
Issue date:	02/12/1993
From:	BAKER J W, FIES C L WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GO2-93-032, GO2-93-32, LER-88-031, LER-88-31, NUDOCS 9302220096
Download: ML17289B167 (9)

Text

ACCELERATE DOCUIVIENT DISTRIBUTION SYSTEM REGULARLY INFORMATION DISTRIBUTIO YSTEM (RIDS)ACCESSION NBR:9302220096 DOC.DATE: 93/02/12 NOTARIZED:

NO DOCKET FACIL:50-397 WPPSS Nuclear Project, Unit 2 Washington Public Powe 05000397 AUTH.NAME AUTHOR AFFILIATION FIESPC.L.Washington Public Power Supply System BAKER,J.W.

Washington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 88-031-01:on 880902,determined that due to single failure CR HVAC sys could operate in recirculation mode.Caused by lack of communication between AE design groups.CR HVAC recirculation mode of operation analyzed.W/930212 ltr.DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR j ENCL j SIZE: C TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.NOTES: D RECIPIENT ID CODE/NAME PD5 LA CLIFFORDPJ INTERNAL: ACNW AEOD/DOA AEOD/ROAB/DSP NRR/DLPQ/LHFB10 NRR/DOEA/OEAB NRR/DST/SELB 8D D SPLB8D1 EG FIL 02 RGN5 FILE 01 EXTERNAL: EGGG BRYCE,J.H NRC PDR NSIC POOREPW COPIES LTTR ENCL 1 1 1 1 2 2 1 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 2 2 1 1 1 1 RECIPIENT ID CODE/NAME PD5 PD ACRS AEOD/DSP/TPAB NRR/DET/EMEB 7E NRR/DLPQ/LPEB10 NRR/DREP/PRPBll NRR/DST/SICB8H3 NRR/DST/SRXB 8E RES/DSIR/EIB L ST LOBBY WARD NSIC MURPHYPG.A NUDOCS FULL TXT COPIES LTTR ENCL 1 1 2 2 1 1 1 1 1 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 D D D D NOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP VS TO REDUCE WASTEI CONTACT THE DOCVMENT CONTROL DESK, ROOM Pl-37 (EXT.504-2065)TO ELIMINATE YOVR NAME FROM DISTRIBVTION LISTS FOR DOCUMENTS YOV DONT NEEDl D S FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 31 ENCL 31 vi WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O.Box 968~3000 George Washington Way~Richland, Washington 99352 February 12, 1993 G02-93-032 Docket No.50-397 Document Control Desk U.S.Nuclear Regulatory Commission Washington, D.C.20555

SUBJECT:

NUCLEAR PLANT WNP-2, OPERATING LICENSE NPF-21 LICENSEE EVENT REPORT NO.88-031-01 Transmitted herewith is Licensee Event Report No.88-031-01 for the WNP-2 Plant.This revised report is submitted in response to the requirements of 10CFR50.73.

It provides an update of the corrective actions and an evaluation of the safety significance that was not available for the original report.Sincerely, J.W.Baker WNP-2 Plant Manager (Mail Drop 927M)JWB/CLF/my 901.24 CC: Mr.J.B.Martin, NRC-Region V Mr.R.Barr, NRC Resident Inspector (Mail Drop 901A, 2 Copies)INPO Records Center-Atlanta, GA Mr.D.L.Williams, BPA (Mail Drop 399)9302220096 930212 PDR ADOCK 05000397 S PDR LICENSEE EV T REPORT (LER)ACILITY NAME (I)Washin ton Nuclear Plant-Unit 2 DOCKET HUMB R ()PAGE (3)0 5 0 0 0 3 9 7 I DF 7 TITLE (4)SINGLE FAILURE COULD CAUSE CONTROL ROOM HVAC TO OPERATE IN AN UNANALYZED OPERATION MODE DUE TO DESIGN EVENT DATE (5)MONTH DAY YEAR YEAR LER NUMBER SEQUENTIAL NUMBER 6)EV I SION UMBER REPORT DATE (7)YEAR DAY MONTH OTHER FACILITIES INVOLVED (8)CKET 00 FACILITY NAMES HUMBE RS(S)0 9 0 2 8 8 8 8 0 3 1 0 I 0 2 I 2 9 3 5 0 050 PERATING ODE (9)HIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 5: (Check one or more of the following)

(11)4 ONER LEVEL (10)0 0 0 20.402(b)20.405(a)(1)(i) 20.405(a)(1)(ii) 20.405(a)(1)(iii) 20.405(a)(1)(iv) 0.405(a)(1)(v) 20.405(C)50.36(c)(1) 50.36(c)(2) 50.73(a)(2)(i)

X 50.73(a)(2)(ii) 50.73(a)(2)(iii) 50.73(a)(2)(iv) 50.73(a)(2)(v) 50.73(a)(2)(vii) 50.73(a)(2)(viii)(A) 50.73(a)(2)(viii)(B) 50.73(a)(2)(x) 77.71(b)73.73(c)THER (Specify in Abstract clew and in Text, NRC orm 366A)NAME LICENSEE CONTACT FOR THIS LER (12)C.L.Fies, Licensing Engineer TELEPHOHE NUMBER REA CODE 5 0 9 7 7-4 1 4 7 COMPLETE OHE LINE FOR EACH COMPONENT FAILURE DESCRIBED IH THIS REPORT (13)CAUSE SYSTEM COMPONENT MAHUFACTURER EPORTABLE 0 HPRDS CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE TO NPRDS 2;l,.'UPPLEMENTAL REPORT EXPECTED (14)YES (If es c iete EXPECTED SUBMISSIOH DATE)NO TAACT OOI EXPEC'TED SUBMISSION MONTH DAY YEAR ATE (15)On September 2, 1988, a Design Engineer determined that due to a single failure the Control Room Heating and Ventilation (HVAC)System could operate in the recirculation mode during emergency conditions.

This unanalyzed condition was found while performing an engineering evaluation of the safety significance of the event reported in LER 88-005-00.

During a Loss of Coolant Accident (LOCA)the normal fresh air intake for the Control Room HVAC is isolated and two remote air intake lines are opened.Each remote air intake line has two isolation valves and one valve is powered from Division 1 and the other from Division 2.A single failure (not a loss of power failure)in a power division could cause a valve in each remote air intake line to isolate.With the loss of all fresh air input the Control Room HVAC would continue to operate but in the recirculation mode.In the recirculation mode the Control Room would not remain pressurized with respect to surrounding areas, and operating post LOCA in this mode was not an analyzed condition.

Immediate corrective actions were: The motor operators for the four (two per line)remote air intake isolation valves were replaced with manual operators.

Two of the four.radiation purge line isolation valves motor operators were electrically disconnected.

Both isolation valves in the remote intake lines were locked open to assure that a single failure could not result in recirculation mode operation.

The Control Room Emergency Filtration System was started and the Control Room HVAC System is operating in the pressurization mode.

LICENSEE EVENT REPOR ER)TEXT CONTINUATION AGILITY NAME (1)Washington Nuclear Plant-Unit 2 DOCKET NUMBER (2)LER NUMBER (8)ear umber ev.No.AGE (3)8 3 1 1 2 OF 7 TiTLE (4)SINGLE FAILURE COULD CAUSE CONTROL ROON HVAC TO OPERATE IN AN UNANALYZED OPERATION NODE DUE TO DESIGN Ab tract nt'd The cause of this event was the Plant Architect/Engineer (AE)did not provide a Control Room HVAC System design which protected the system against all possible single failures.The root cause of this event is a lack of communication between AE design groups.Further corrective actions were taken: The Control Room HVAC recirculation mode of operation was analyzed.Technical Specification Amendment No.74 was received allowing Control Room HVAC operation with the revised configuration.

A letter was sent to Burns&Roe Inc.providing notification of a potential 10CFR Part 21 condition.

PI n Con i ion Power Level-0%Plant Mode-4 (Cold Shutdown)Event De ri ti n On September 2, 1988, a Design Engineer determined that, due to single failures, the Control Room Heating and Ventilation (HVAC)System could operate during emergency conditions in the recirculation mode, which is an unanalyzed condition.

This unanalyzed condition was discovered while performing an engineering evaluation committed to in LER 88-005-00 to evaluate the potential effects of minor Control Room HVAC system changes on system bypass flow.The following brief description of the Control Room HVAC System (before modification) for normal operation and emergency operation during a Loss of Coolant Accident (LOCA)is presented to aid in understanding the event and the changes made to the system.Figure 1 is a partial diagram of the Control Room HVAC System prior to the event.The Control Room HVAC System consists of two redundant systems for both normal and emergency operation.

During normal operation, 1000 cfm of fresh air from the normal roof intake Radwaste Building is mixed with 20,000 cfm of recirculated air (through fan 51A or 51B).Seven hundred and fifty (750)cfm is exhausted from the control room through fan 51 and the remaining 250 cfm pressurizes the control room and is exfiltrated.

Also during normal operation, the remote air intake isolation valves (51A and B and 52A and B)are closed and the radiation monitor purge line valves (51D and E and 52D and E)are open with radiation monitor purge line fans 53A and B operating.

During a LOCA when any of the following trip levels are reached 1)High drywell pressure ("F" signal), 2)Low low reactor water level ("A" signal)or 3)Reactor building ventilation exhaust high radiation ("Z" signal)the following actions occur: a)The normal roof intake Radwaste Building is isolated by closing valves 51C and 52C.

LICENSEE EVENT REPOR LER)TEXT CONTINUATION AGILITY NAME (1)Washington Nuclear Plant-Unit 2 I OOCKET NUMBER (2)0 5 0 0 0 3 9 7 ev.No.8 031 01 LER NUMBER (B)ear umber AGE (3)3 F 7 1TLE (4)SINGLE FAILURE COULD CAUSE CONTROL ROOM HVAC TO OPERATE IN AN UNANALYZED OPERATION MODE, DUE TO DESIGN b)The 750 cfm control room exhaust fan (51)deenergizes.

c)The remote air intake isolation valves (51A, 51B, 52A, and 52B)open and the radiation monitor purge line isolation valves (51D, 51E, 52D and 52E)close.The remote air intake isolation valves and the radiation monitor purge line isolation valves are interlocked so when an intake line is opened the associated purge line is isolated.d)The control room emergency filtration system is automatically started and draws 1000 cfm of fresh air through the remote air intakes.This additional air, when added to the recirculated air, pressurizes the control room.The event described in LER 88-005 was for leakage around the emergency filters in excess of the technical specification allowable limit.During the engineering evaluation committed to in LER 88-005 to determine the effect of the excess leakage on control room habitability, a design engineer determined that postulated single failures could cause some combination of remote air intake line isolation valves to fail to open or to reisolate and;thus, isolate both remote air intake lines.If this condition existed during LOCA conditions, the Control Room HVAC would be running in a recirculation mode only since the normal roof intake is also isolated.In the recirculation mode the 20,000 cfm would continue to be drawn from the control room and recirculated back to the control room;however, without the fresh air input the control room would not be pressurized.

In a neutral pressure condition the inleakage to the control room would increase and this condition is not analyzed.Imm iateAci n The planned Plant Startup was delayed until the following actions were completed.

1)The motor operators were removed and manual operators were installed on the remote air intake isolation valves (51A and B and 52A and B).The valve operators were changed to manual so the isolation valves on the remote intake lines could be opened without an FAZ signal present;thereby, assuring that a single failure could not cause operation in the recirculation mode.With the remote air intake lines open, the control room emergency filtration system is started, fan 51 is deenergized, and the associated damper is closed.This put the Control Room HVAC system in the pressurization mode of operation which satisfied the action statement of Technical Specification 3.3.7.1.The current Plant configuration has both remote intakes open during normal operation.

Figure 2 shows the post event Control Room HVAC configuration.

2)Two of the radiation purge line isolation valve electro-pneumatic operator motors (52D and 51E)were electrically disconnected which causes the valves to open.This was done so that only one manual action is required to isolate a remote path and cause the associated purge path to open or vice versa.3)The 750 cfm control room exhaust fan (51)was deenergized.

4)Specific directions for Plant Operators to execute to maintain design bases in the event of a LOCA were provided in (approved) deviated Plant procedures.

Each new operations crew was provided training by Operation Managers.

LICENSEE EVENT REPOR LER)TEXT CONTINUATION AGILITY NAHE (I)Washington Nuclear Plant-Unit 2 00CKET NUHBER (2)0 5 0 0 0 3 9 7 Year LER NUHBER (8)umber ev.No.AGE (3)8 031 01 4 F 7 TITLE (4)SINGLE FAILURE COULD CAUSE CONTROL ROOM HVAC TO OPERATE IN AN UNANALYZED OPERATION MODE DUE TO DESIGN Further Evaluati n and orrective Action A.Further Evaluation This event was reported per 10CFR50.72(b)(2)(i) on September 2, 1988 at 1702 hours0.0197 days <br />0.473 hours <br />0.00281 weeks <br />6.47611e-4 months <br />.The event is also reported per 10CFR50.73(a)(2)(ii)(A).

There were no structures, systems, or components inoperable prior to this event which contributed to the event.The cause of this event was the failure of the Plant Architect/Engineer (Burns&Roe Inc.)to provide a system design for which a single failure could not isolate both remote air intakes and cause the Control Room HVAC System to operate in the recirculation mode, or to analyze the recirculation mode of operation.

The root cause of this event is a lack of communication between the Architect/Engineer design groups.B.Further Corrective Action 1)The Control Room HVAC recirculation mode of operation was analyzed.The results are summarized under safety significance below.2)Technical Specification Amendment 74 was received allowing operation of the Control Room HVAC system in the revised configuration.

3)A letter was sent to Burns&Roe Inc., providing notification of a potential 10CFR Part 21 condition.

~Sf ii lit~i The safety significance of operation in the recirculation mode has been evaluated.

The results are documented in Technical Memorandum TM-1158, Revision 4.The calculation assumed Control Room inleakage in the range of 350 to 450 cubic feet per minute.The calculated whole body gamma dose and skin beta dose were within limits.However, the calculated thyroid dose was approximately 100 Rem which exceeds the Standard Review Plan 6.4 limit of 30 Rem.It is therefore concluded that this event has safety significance as a single failure during LOCA conditions could have resulted in Licensing Basis Document (LBD)limits being exceeded.imil r Ev n None LICENSEE EVENT REPOR ER)TEXT CONTINUATION AGILITY NAME (1)Washington Nuclear Plant-Unit 2 OOCKET NUMBER (2)0 5 0 0 0 3 9 7 LER NUMBER (8)ear'(umber ev.No.8 031 01 AGE (3)5 OF 7 ITLE (4)SINGLE FAILURE COULD CAUSE CONTROL ROOM HVAC TO OPERATE IN AN UNANALYZED OPERATION MODE DUE TO DESIGN E~f Tex R f ren f*/~Lcm m~mm~nen Control Room Heating and Ventilation (HVAC)System Normal Fresh Air Intake (Normal Roof Intake Radwaste Building)Remote Air Intake Line, (East or West)Remote Air Intake Isolation Valves (51A and B and 52A and B)Remote Air Intake Isolation Valve Motor Operator (Electro-Pneumatic Motor Operator)Radiation Purge Line Isolation Valves (51D and E and 52D and E)Radiation Purge Line Isolation Valve Motor Operator (Electro-Pneumatic Motor Operators)

Control Room Emergency Filtration System Fan 51A or 51B 750 cfm Control Room Exhaust Fan (51)Radiation Purge Live Exhaust Fans (53A and B)VH VH VH VH VH VH VH ISV 84 ISV 84 FAN FAN FAN LICENSEE EVENT REPOR ER)TEXT CONTINUATION AGILITY HAHE (I)Washington Nuclear Plant-Unit 2 OOCKET HUHBER (2)0 5 0 0 0 3 9 7 LER HUHBER (8)ear umber ev.Ho.8 031 1 AGE (3)6 F 7 ITLE (4)SINGLE FAILURE COULD CAUSE CONTROL ROON HVAC TO OPERATE IN AN UNANALYZED OPERATION NODE DUE TO DESIGN I RCHOTE INTAKC I I 01 I L Rc IV 11 RC AH TYPICAL , I vhLvcs I'OPQ<OJJ I FAX I I gna>>>>52B 5IB+DJV II I I Dlv I CHER G FILTER II II II II II II'~JI I I I I 0 SIKE 52C DIV ll r-M" 5ZA I FGDIV II EHER6 FILTER I I I I I I L I DIV ll 50B-I Dlv I 5<A-I~5 I A DIV Il I I I I I I I I.r" I I 5IA-I IB"I DIV I V II FAM 50B DIV II FAN 50A DIV I FAN 5IB Dlv 11 FAN 51A Dlv I CONTROL ROON VALVES CLOSC NORHAI ROOF ON HIGH-HJQI INTAKC I RADIATION ALARM RADVASTE VALVES<TYPICAL>BLDG OPEN OW I FAX 0 EHO 5IC DIV I CLOSC OM fAX RLHOTE OITAKC lz<EASTI DIV I RC J RR TYPICAL EHO EHO 0 5ID FO 52DFO DIV I Dlv 11 154 CTH~EHO EHO FO FO Dlv Il DIV'I FC>>fAIL CLOSED FO>>FAlL OPOI NC>>JCRHAl.LY CLOSED NO>>NORMALLY OPEN LO>>LOCKED OPEN LC>>LOCKED CLOSED Q>>ANNNCJATOR 14 RE>>RAD ELEMENT RR>>RAD RECORDER EHO>>ELECTRO HYDRAILIC OPERATOR HAN>>HAJIUAL OPERATOR FAH 53A'AH 53B DIV I DIV II PURGE CKJJAUST FAX>>HJQI DRYVELL PRESSUREJ LOV REACTOR VCSSEL VATER LEVELJ REACTOR BUILDIHG VOITJLATION EKHAUST HIGH RADIATIOK IJJFORHATION DRAVJNG DNLY SEPT 22.1888 954 CFH EXHAUST DEEHERGIXE ON fAX FAH 51lI'AOIQKGToN Pvouo PoYKA 43 SUPPLY SYSTEM'IEtulGL VATHlJJGTOH 993524968 TJTLC ORIGINAL VNP 2 I'ARTJAL CONTROL ROON VENTILATION SYS Figure 1 Pre-Event Control Room HVAC LICENSEE EVENT REPOR ER)TEXT CONTINUATION AGILITY NAHE (1)Washington Nuclear Plant-Unit 2 OOCKET NUHBER (2)0 5 0 0 0 3 9 7 ear LER NUHBER (8)umber ev.No.AGE (3)8 3 I I 7 F 7 ITLE (4)SINGLE FAILURE COULD CAUSE CONTROL ROOM HVAC TO OPERATE IN AN UNANALYZED OPERATION NODE DUE TO DESIGN QRE IV II RKHOTE ItNAKC et WEST>ttAH IRIRttnL Ruof It t IAKC RADVASTC tto Qtto Pf 51C DIV I~FC cLosc ott rnz Hntt HO~Etto 52C DIV II rc DIV Il ste-t FHKRG FILTER HAtl H tIAH l DIV 11)DIV I EIIERG FILTER RQIOTE It t TAKE e2 (EAST)Dlv I RR T YPI CAI.TYPICAL rnu 5th DIV I 5th-I DIV I 31 D-I)V It rnN sic DIV II DKTERN'D El lO FAN 5IA DIV I TAN 51D DIV II cottTRUL Relet DE'TERN'D slo ro Score DIV I DIV II FO523 FO 51 DIV II DIV I LEKIQl FLOV Itl LOIC~Ito FLOV IH LlttE FC>>FAIL CLOSED FO>>I'AIL OPEN IIC>>ttORHALLY CLOSED NO>>IIORHALLY OPEN LO>>LOCKED OPEN LC>>LOCKED CLOSED A,~ntotuttctntoR to RE RAD ELKHEHl'R>>

RAD RECORDER Et to>>ELECTRO IITDRAULIC OPERATOR Hntt>>HAIIUAL OPERA'TOR rntt 53n F'nN 53B DIV I DIV II" PURGE CXIIAUST rnw sl~TSO CFH EXHAUST DELIIERGIZE OH FAZ f'AZ IIIQI DRYMELL PRESSUREI LOV REACTOR VCSSEL VAILR LEVELt REACTOR DUILoltlo vEHTILATIotl ExttnusT IIIQI RADIATIUIL IttreettnttOH DRnvlHG QILY SEPt 27.19oo xtotoxotott rootle ronn b3 svpvu'vsYFw RIEIILAIIIL MASIIIIIGION 99352-0968 1ICLC pRoposKD vtlp 2 pnRtlnL cotttRUL Roott vEttllLATIUtl sts Figure 2 Post-Event Control Room HVAC