IR 05000285/1987027

Enforcement Conference Rept 50-285/87-27 on 871029.Major Areas Discussed:Concern of Water Entering Instrument Air Sys.List of Attendees & Licensee Presentations Encl

ML20236N616
Person / Time
Site:	Fort Calhoun
Issue date:	11/10/1987
From:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:
Shared Package
ML20236N598	List: IR 05000285/1987027 ML20236N595
References
50-285-87-27-EC, NUDOCS 8711160252
Download: ML20236N616 (25)

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OMAHA PUBLIC POWER DISTRICT-0CTOBER 29, 1987 -

MEETING SUMMARY

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. Licensee: Omaha Public Power District (0 PPD)

Facility: FortCalhounStation(FCS)

License No.: DPR-40 ,

Docket No.: 50-285

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SUBJECT: -ENFORCEMENT CONFERENCE CONCERNING NRC IN3PECTION FINDINGS (INSPECTIONREPORT 50-285/87-27)

s On October 29, 1987,- representatives of Omaha Public Power District, met in j Arlington, Texas, with NRC Region IV and NRR personnel to discuss the findings documented in the NRC Inspection Report dated October 23, 1987. The .

attendance list and licensee presentations are attached. The meeting was held at the request of NRC, Region I <

' The NRC discussed the concern of water entering the instrument air syste The licensee discussed the cause of the water in the instrument air system as well-as the corrective actions taken to eliminate the water that entered the

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system. The licensee stated that the instrument air system will be separated from any potential water source ,

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' Enclosures: Attendance List

' OPPD Presentations

8711160252 871110 gDR ADOCK 05000285 PDR

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ENCLOSURE 1 ENFORCEMENT CONFERENCE ATTENDANCE LIST - REGION IV 1 OMAHA PUBLIC POWER DISTRICT  ;

I-NRC Attendees:

L. J. Callan, Director, Division of Reactor Projects, RIV i A. B. Beach, Deputy Director, Division of Reactor Projects, RIV  ;

J.. E. Gagliardo, Chief, Operations Branch,' RIV j T. F. Westerman, Chief, Reactor Project Section B, RIV D. R. Hunter, Chief, Technical Support Section, RIV

' W. C. Seidle, Chief,~ 0perational Programs Section, Region IV P. H. Harrell, Senior Resident Inspector, Fort Calhoun j

. A. Powers, Enforcement Officer, RIV  !

A. Bournia, Project Manager, NRR l H. L. Scott, Enforcement Staff; RIV 1 A. R. Johnson,' Reactor Inspector, RIV

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R. P._Mullikin, Project Inspector, RIV_

Licensee Attendees:  :

R. L. Andrews, Division Manager, Nuclear Production W. G. Gates, Manager Fort Calhoun Station T. L. Patterson, Manager, Technical Support M. E. Eidem, Manager, Mechanical Engineering S. K. Gambhir, Section Manager, Generating Station Engineering

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T. J. McIvor,. Supervisor, Technical 1

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M. R. Core, Supervisor, Maintenance J. J. Fisicaro, Supervisor, Nuclear Regulatory'and Industry Affairs i

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1. '  ? ENCLOSURE 25/ e '( 1

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Opening' Remar _

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- Description'of Instrument-Air System

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• < -~ Design Description /USAR .

- Fire Protection Modification'Ir. stalled 1985

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II; July 6, 1987 Fire Protection Surv. Test

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. g Performed T. J. McIvor

, Describe Surveillance; Test /Maint.' Procedure .i-LSequence of Events j:

' Investigation (what happened)

- What immediate actions taken

- What long: term actions taken/ planned ,;

- Results.offactions ,

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~II September 23, 1987 DG-2 Surveillance Test T. L. Patterson Tech. Spec., Sectio'n 2.7_- 0

- Diesel (Gen. Testing.7/6/87 - 9/22/87

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. . Sequence of Events

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investigation

- What immediate actions taken

- Results of~ actions

- Mitigating circumstances  !

- Conclusions

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I Long Term Actions T. L. Patterson i

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- AEOD/IEN Review l Walk Down of System i

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-Summary / Engr.: Perspective S. Gambhi=

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-1 Summary /0&M Perspective _ G. Gates  !

Closing Remarks R. L. Andrews )

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INSTRUMENT AIR SYSTEM OVERVIEW

' ALL 0F THE MAJOR AUXILIARYCOMPONENTS BUILDING ON THE. EAST OF THE SIDE, INSTRUMENT ROOM 1 AIR' SYSTEM ARE LOC

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AIR IS SUPPLIED BY THREE IDENTICAL TWO STAGE COMPRESSORS OF WILL OPERATE AUTOMATICALLY WHILE THE THIRD IS KEPT ON STANDB OPERATED MANUALLY IF NECESSAR .

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THE COMPRESSORS /,RE CONNECTED TO A DISCHARGE MANIFOLD THAT FEEDS THE INSTRUMENT AND SERVICE AIR SYSTEN INSTRUMENT- AIR FLOWS FIRST THROUGH AN AIR RECEIVER TNAT HO SUPPLY OF AIR. FROM THE RECEIVER IT FLOWS THROUGN AN AIR DRIER, FILTERS AND THEN TO THE DISTRIBUTION SYSTE SYSTEM OPERATION IS NOT REQUIRED TO INITIATE OPERATION OF EN SAFEGUARDS EQUIPMEN INSTRUMENT SYS1E AIR IS NOT REQUIRED FOR OPERATION OF THE REACTOR

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LOSS PLANT OF INSTRUMENT AIR DOES NOT PRESENT A MAJOR HAZARD DUR

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IS NOT OPERATION OR HITIGATION OF AN ACCIDENT SITUATION BECAUSE T REQUIRED FOR SAFE SHUTDOWN, EXCEPT FOR NECESSARY AUXILIARY AIR SYSTEMS (ACCUMULATORS).

REACTOR SIGUAL CAN BE TRIPPED AND CONTAINMENT ISOLATED USING ELEC

AIR OPERATED VALVES REQUIRED TO OPERATE 00 SO BY SPRING ACT BY AUXILIARY AIR SUPPLY (IE ACCUMULATORS) FOLLOWING REMOVAL PRESSURE FROH THEIR OPERATOR *

INSTRUMENT AIR SYSTEM IS NOT SEISMICALLY SUPPORTED EXCEPT FOR NECESSARY AUXILIARY AIR SUPPLY SYSTEM *

INSTRUMENT AIR SYSTEM IS E0I SAFETY RELATED, .EXCEPT FOR NECESSARY AUXILIARY SYSTEM .

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FIRE PROTECTION MODIFICATIONS  :

USING INSTRUMENT-AIR  ;

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DRY PIPE SPRINKLER SYSTEM FOR DIESEL _ GENERATOR R00MS--(MR-FC-83-182).

SYSTEM INSTALLED TO REDUCE THE POTENTIAL FOR FREEZING SPRINKLER

• PIPING'WHEN THE DIESEL GENERATORS ARE OPERATED DURING COLD WEATHE .

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SYSTEM' UTILIZES A 4-INCH DRY PIPE VALVE THAT FEEDS BOTH D.G.-ROOMS j VIA . COMMON HEADE ALL' SYSTEM PIPING IS PRESSURIZED TO :

APPR0XIMATELY 40. PSI WITH INSTRUMENT AIR. WHEN AIR PRESSURE IN THE- l SYSTEM JS REDUCED TO A PREDETERMINED POINT, THE DRY, PIPE VALVE OPENS y ALLOWING THE PIPING SYSTEM 10 FILL WITH WATE j

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INSTRUMENT AIR USED FOR SEVERAL REASONS:.

,( 1 MINIMIZE ADDITIONAL' COMPONENTS THAT REQUIRE PERIODIC MAINTENANCE (ADDING DEDICATED COMPRESSOR WOULD ADD ADDITIONAL MAINTENANCE).

PROVIDE A CLEAN, DRY SOURCE OF COMPRESSED AIR, THUS MINIMIZING THE POTENTIAL FOR MOISTURE COLLECTION AND'POSSIBLE FREEZING'WITHIN THE i SYSTE l

s THE FOLLOWING CHECK' PECHANISMS PROVIDE ASSURANCE AGAINST WATER IN

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t 1) DRY PIPE CLAPPER i

2) CHECK VALVES IA-575 & IA-576 1 j

3) AIR MAINTENANCE DEVICE IA-6 l

• THE DRY- PIPE VALVE, IF THE CLAPPER IS RESET WILL NOT ALLOW WATER UP- i TO IA-576, THEREFORE, THE 0NLY TIME WATER WILL BE AT IA-576 IS DURING SURVEILLANCE TESTING AND AN ACTUAL FIRE CONDITIO '

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• l VENDOR RECOMMENDS USE OF ONLY ONE CHELK VALV l l

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' \".4 k MAINTENANCE DEVICE

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Drive Screw #7 x 5/16 Lg 1 s ~ A Adjustment Screw 1

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• Ava lable in Sub Assemblies only 1/16' = 1.59 mm 35 p: = 241,0 kPa 1/4* = 6.35 mm 40 psi = 76,0 kPa SUS ASSEM8tlE5 5 psi = 34,5 kPa 45 psi = 310,0 kPa PARI NO, l

10 psi = 68,9 kPa 50 p;l e 345,0 kPa IT EM NO, DESCRIPilON REQ' j 15 psi = 103,0 kPa 75 psi = 517,0 kPa 10,11,13 J 20 psl = 138,0 kPa 25 psi = 172,0 kPa 100 psi = 689,0 kPa 150 psi = 1034,0 kPa thru 21 1,2,4 02269 8 02272A Housing Assembly Advstment Screw Assb ( i 30 psi = 207,0 kPa 175 psi = 1206,0 kPa 8&9 01792A Diaphragm Assembly 1 19 & 21 03007A Filter Kit 1 Part No. 04909 F Form No. 2114 Printed in U. l l

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OPERATION i

The Reliable Model D Dry Pipo Valve in its closed and open specifies that Oulck Opening Devices are required in Dry Sys-positions is shown in Figures 1 and 2. The closed position is tems having capacities of more than 500 gallon maintained as long as the air pressure in the system piping Rellable's Model B Accelerator is an approved Oulck Opening above the Dry Pipe Valve is suf ficient to exert a greater force Device that is easily attached to Hellable's fry Pipe Valves, on the top side of the clapper than is exerted on its underside The accele: Hof is sensitive to small drops In system pressure by the pressure of the water supply. Since the area included by and its qt.lck operation allows the system air to pass through the Air Seat is approximately six tim (s that of the Water Seat to the alarm cutlet and the underside of the clapper. Here the (The Dif ferential Principle) the air pressure needed to keep the air pressure build-up, coupled with the pressure of the Water Dry Pipe Valve closed is only a fraction of tnat of the water supply, opens the Dry Pipe Valve clapper permitting the water supply. Table 1 gives the recommended air pressure for various to flow instantly to the operated sprinkler (s).

water supply pressures for both sizes of Model D Dry Pipe

" Rollable's Model 0 Accelerator is described in greater detailin separate bulletin ()!

I Water Pressu e Air Pressure l in Supply Line To be Pumped into System VALVE DESCRIPTION 1. Rated working ptessure 175 pst(12.1 bar)

Maximum Not less than Not more than 2. Factory hydrostatic test pressure 350 psl(24.1 bar) l 3. End and trim connections-Three valve connection styles I are availabl a. US Standard Flanged inlet and Outlet ,

100 25 35 * Flanges male with ANSI B 16.1 (125 lb.) Flange 125 30 40 150 35 45 U.S. FLANGE DIMENSIONS IN INCHES US 40 50 Valve Soit Dott Flange Flange No Table 1 Size Circle Hole Outside Thickness Bolts When one or more Automatic Sprinklers operate due to fire, Di Di Di the air pressure in the system piping above the Dry Pipe Valve 4 7% % 9 uha 8 l Is reduced. The pressure of the water supply, now by exerting 6 9% % 11 1 8 l the greater force, raises and rotales the Clapper to its open I position, permitting the water to flow to the operated Sprin- * Threaded openings per ANSI D kier(s). Water also flows from the Alarm Outlet of the Dry Pipe , ,

Valve through a strainer to the Reliable Mechanical Sprinkler Alarm and Electric Marm Switch to automatically actuate Flanged Valve '

mechanical and electrical alarrn * Color-Light Gray Retlable Model D iry Pipe Valve can be reset quickly and b US Standard Flanged inlet and Grooved Outlet (Fig.3)

easily without the use of special tool * Inlet flange mates with ANSI B 16.1(125 lb.) Flange OUICK OPENING DEVICES U.S. GROOVF DIMENSIONS IN INCHES When .an automatic sprinkler operates the resulting air pres- Valve Outlet Groove Groove Outlet Face f sure decay is inversely proportional to the size of the Dry Size Di Di Width to Groove (

System the larger the system, the slower the air pressure 4 4.500 4.334 3/8 5/8 decays which slows the operation of the Dry Pipe Valve. NFPA Pamphlet No.13 titled " Installation of Sprinklar Systems" 6 6'625 6.455 3/8 5/8

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July 6, 1987, Water in Instrument Air Event Instrument Air System Important to station operation Historically - only minor problems; a few instances of plugged orifices, et ST-FP-5 - Includes Test Actuation of Dry Pipe Sprinkler System for DG Rooms Fire protection water supply is screened river water FP header pressure maintained at approximately 125 psig by jockey pump, using service water Dry pipe system normally maintained at approximately 40 psig air pressure from IA system Test actuation initiated by bleeding down the air pressure Following test actuation, dry pipe valve is reset by performing MP-FP-7 l

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V j Sequence of Events - Based on Dis' c ussions with Personnel Involved i

- Test initiated per ST-FP-5 ' ST says to reset per applicable steps of MP-FP-7; not clear as to where to begin Closed FP-514, but did not reset clapper Entered reset procedure at point of priming FP-513. Operator thought that FP-513 was like the pre-action deluge valves; self-reset when pressure removed. Actually, one-of-a-kind dry pipe valve requiring manual rese . Opened FP-516 and poured priming water into body of dry pipe valve Closed IA-570; isolated air maintenance device l Opened IA-569; noted water blowing out of FD !i3 Opened FP-514; noted that both air and water pre:sure gauges on valve were at fire main pressure; knew this was abnormal Opened IA-574;~ stream of water; knew at this point that there may be water in the IA system 1 Isolated system; discussed with shift supervisor; M0 written to perform maintenance on check valves and reset dry pipe valve 1 Some component problems over the next hour pointed to water in the IA system; FC-269X, bubbler for DG fuel oil tank, HCV-485

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' Evaluated.Cause of Event Check valves IA-575 and IA-576 were prevented from closing fully by foreign material When FP-514 was-opened, water entered the IA system because the clapper in FP-513 was not reset, IA-569 was open and the wate j pressure was approximately 30 psi greater than the air pressur ' Procedural inadequacies were a major contributing factor

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- Immediate Actions 1. . Performed maintenance.on check valves.IA-575 and IA-576; restored 3

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2.. . Reset the dry pipe. valve, FP-513

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. Began blowdowns of IA ' system in the vicinity of FP-513, extending into areas where we discovered water and/or operational problems l

'  ! By the end of the day, we felt that substantially all water had been removed from the system and full operability restored i Began an engineering investigation of the problem; scope of blowdowns required, et ", Blowdown Program - Determine Extent of Water Intrusion and Document Its )

Removal ' Began drawing review Monday PM Walkdowns performed Tuesday to determine possible paths of water, et . Procedure and data sheets prepared Wednesday I&C began detailed blowdowns and component cycling on Thursday G.- Phase I - July 1987 components blown down; valves cycled and components actuated except where not possible during operation

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L; components from 11 risers had water

Water confined to lower two levels of the auxiliary building; none in turbine building or intake structure; did not reach level of IA penetration in containment l

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l Phase II -' August 1987 'll risers from Phase'I blown down completely- i

._ locations on 4 risers showed mis '

i 1 Phase III - September 1987 Planned to blow down the 4 risers showing mist in' August  ! Data sheets issued to maintenance but wo'rk not completed when DG-2

-

event of September occurred i

'

i

J . Air Accumulators- ' Researched P&ID's'to determine'which CQE in affected areas are: '!

equipped with accumulators Drained or? blew down accumulators; one had 12.5% water, two others  !

-

had a small amount; all in110wer level of auxiliary building i DG exhaust damper accumulators were missed,because they are not shown on the P&ID; different type of accumulator' application I&C technician who blew down DG headers believed 1that his actions blew down the accumulators as well; this was later determined to not be the case Procedural Inadequacies - Procedure Changes Are Being Prepared to-Correct ,

i Long Term . Actions Planned as a Result of the July 6 Event (Taken from  !

Report to PRC Dated August 3, 1987)' EEAR FC-87-32 written to reevaluate / remove IA from FP-513 Plan developed to disassemble sample of valves and instruments and-inspect for adverse effects of moisture intrusion

.. Consider cleaning / system flush during 1988 refueling outag .

(

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l DG-2 FAILURE SEQUENCE OF EVENTS

!

SEP 22, 1987 DG-1 STARTED TO VERIFY OPERAb. ;ITY PRIOR TO COMMENCING DG-2 MAINTENANC SEP 23, 1987 0906 BEGAN ST-ESF-6 ON DG-2 TO MEET TECH SPEC REQUIREMENTS FOR MONTHLY FULL LOAD TES , 5 MINUTES AFTER STARTUP, COMMENCED LOADING DG- , 14 MINUTES AFTER LOADING, DG-2 SHUTDOWN ON HIGH COOLING TEMPERATUR INTITIATED IMMEDIATE INVESTIGATION THAT INCLUDED CALL TO EM ABOUT THREE HOURS AFTER TRIP THE DAMPER TO THE RADIATOR FAILING TO FULLY OPEN WAS THOUGHT TO BE MOST PROBABE CAUS *

l 1610, AFTER CONFIRMING DAMPER PROBLEM 01 DG-2, BLOCKED OPEN DAMPER ON DG- COMMENCED DETAILED INVESTIGATIO g 7- -,,-- ,  ; ,

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S CORRECTIVE MEASURES

o REINITIATED PHASE I. BLOWDOWN / CYCLING PROGRAM.(538 COMPONENTS TO DATE)

o PERFORMED JCO FOR CQE. VALVES'NOT CYCLED DURING ANY OF THE THREE PHASES (34 VALVES TOTAL) l i

i o ISOLATED IA (FROM WETTED / PRESSURIZED TIE-INS

--.

o REPAIREb HCV-871F AND HCV-871G j

,

o COMMENCED'WALKDOWN OF IA SYSTEM TO VERIFY COMPLETENESS r OF BLOWDOWN / CYCLING PROGRAM o-INITIATED DEW POINT SAMPLING PROGRAM. INITIAL RESULTS INDICATE NEED TO REPLACE DESSICAN ;

'

i

' o REVIEWED ISI PROGRAM STROKE TIME RESULTS/ INCREASED FREQUENCY OF TESTING TO MONTHLY ,

l l

o COMMENCED DEVELOPMENT OF STROKE TIME MONITORING PROGRAM i FOR VALVES NOT INCLUDED IN THE ISI PROGRAM (11/15/87)

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CORRECTIVE ACTIONS (Cont)

o INITIATED PROGRAM TO VERIFY AIR OPERATED VALVE DESIGN BASES

o EXPEDITING MODIFICATION TO PERMANENTLY SEPARATE IA FROM PRESSURIZED WETTED SYSTEMS (f. h.4 L.yG/d f N * O OC o COMPLETE REWRITE OF AOP-l'/ FROM A TECHNICAL AND HUMAN FACTORS PERSPECTIVE o WILL EVALUATE EXISTING PM PROGRAM FOR IA COMPONENTS AND REVISE AS NEEDED TO IMPROVE CONFIDENCE ON OPERABILITY o CONTINUE TO INVESTIGATE METHODS FOR DETERMINING THE PRESENCE OF REMAINING WATER o ISSUED MO'S TO DISASSEMBLE AND INSPECT TWO VALVES KNOWN TO HAVE BEEN EXPOSED TO WATER (WAITING ON PARTS)

,

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DESIGN BASIS VERIFICATION l

. ACTIVITIES UNDER CONSIDERATION oPROCEDURE REVIEW - REVIEW NORMAL, EMERGENCY AND ABNORMAL' OPERATING PROCEDURES TO VERIFY THA ARE WRITTEN IN ACCORDANCE WITH THE DESIGN BASI RESPONSIBILITY-TECH SERVICES eFUN_CTIONALITY CHECK - VERIFY THE ABILITY OF SAFE AND REQUIRED SUPPORT SYSTEMS TO PERFORM THEIR INT -

FUNCTIONS IN NORMAL AND POST ACCIDENT MODE RESPONSIBILITY-GSE/ PROJECT TEAM

- VERIFY ADEQUACY OF

• LIMITED SCOPE SSFI' S ( AUDITS)

MAINTENANCE, IN-SERVICE INSPECTION, AND TRAINING ACTIVITIE RESPONSIBILITY-CA/RA

'

eSAFETY EVALUATIONS - REVIEW MODIFICATION PACKAGES CONFIRM ADEQUACY OF SAFETY EVALUATION RESPONSIBILITY-GSE/ PROJECT TEAM

- __-_-_-. _____ _ __ _

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DESIGN BASIS VERIFICATION 1

( CONT' D)

- ACTIVITIES COMPLETED-

• VERIFICATION AND RECREATION OF SEISMIC DESIGN BASIS i

• 79-02 AND 79-14 EFFORT

.* TECHNICAL RESOLUTION OF A-46 (NOT COMPLETED)

• 10CFR50.49-DESIGN BASIS FOR ELECTRICAL EQUIPMENT REQUIRED  ;

FOR POST ACCIDENT OPERATION WAS RECREATED AND-  !

VERIFIED PER 10CFR50.4 '

!

• DOCUMENT UPDATING EFFORT

]

MODIFICATION' PACKAGES UPDATED 1,053 MAINTENANCE ORDERS REVIEWED 30,400 DRAWINGS UPDATED 2,383 NEW DRAWINGS CREATED 265 P&ID WALKDOWNS DONE 3 TIMES

~

• CHAMPS DATA BASE (20,400 PIECES OF EQUIPMENT)

-

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• OTHER

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-

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-

IMPROVEMENTS IN DOCUMENTATION.0F ENGINEERING JUDGMENT AND EVALUATION

.

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' TRAINING

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_ _ . _ - - - . - - - . - - . , , - . - -.a._----- - A

_ _ _ _ _ - _ _ _ _ . _ _ _ _ _ _

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WCJ(2), M0G, DDW, RLA, RLJ, KCH, JTG, TLP,.KJM, JJF, RKS, JMM, JBK, DJM, TPM(3),

LLG, JRG, RLP, DKD, BC, JGS, RKB, FFF,, KET, LLZ, RGE

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Omaha Public Power District 1623 Harney Omaha, Nebtsska 68102 402/536 4000 October 23, 1987 LIC-87-720 U. S. Nuclear Regulatory Commission '

ATTN: Document Control Desk Washington, DC 20555 i

Reference: Docket No. 50-285 l l

SUBJECT: Licensee Event Report for the Fort Calhoun Station

]

Gentlemen:

Please find attached Licensee Event Repurt 87-025 dated October 23, 198 This report is being submitted per requirements of 10 CFR 50.7

Sincerely, hl:8u R. L. Andrews Division Manager Nuclear Production RLA:rge Attachment ]

l c: R. D. Martin, NRC Regional Administrator A. Bournia, NRC Project Manager f P. H. Harrell, NRC Senior Resident Inspector l {

INPO Records Center l American Nuclear Insurers l SARC Chairman i PRC Chairman, % R. G. Ellis

-

Fort Calhoun File (2)

S. Clayton Fort Calhoun Station Training, % J. J. Fluehr P

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LICENSEE EVENT REPORT (LER)

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ocener Nuu... ui un m l

, ,1,urv =aus ni Fort Calhoun Station Unit il o I s I o I o I o 121815 1 loFl 0 f 6 fif te 44'

DG-2 Shutdown on High Coolant Temperature aeront care en orwen paciuties servotvan sei evez, oat e in I Lea Numeen en car occasr Nuusamiss uoNTM vtAn i vtaa * * M ',' ' *iL*,% woNrs vaan 'aciurv =awas it otsioiotoi i i

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T. L. Patterson, Supervisor Technical 40:2 4:26 i i i i4 1 0 i lil COuPL878 0N4 LiNE 804 ( ACH COuPO84 TNT F A8Lumt Ot3CRIG4D IN fMid A GPOMT n3B

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-} ,8,,,, n . _ -- aurcruo suswwon,--.--.---~~na u rts ] No iuu.c1,o,.,,,,,. On September 23, 1987, at 0906 COT, following repair of the exhaust pipe, Diesel i Generator No. 2 (DG-2) was started and loaded per Operating Instruction 01-DG-2 as required by Surveillance Test ST-ESF-6. Approximately 14 minutes into the test, DG-2 automatically shutdown due to high coolant temperatur Investigations revealed that the air operated exhaust damper for the diesel generator radiator may not have fully opened automatically as designed when the diesel was running, thus restricting the required air flow through the radiato The cause of the damper malfunction was postulated to be the presence of residue causing the pilot valve that directs air flow to sometimes stick. On July 6, water was introduced into the instrument air system during the performance of a surveillance test on the fire protection system dry pipe valve for the diesel generator room The water intrusion was limited to the auxiliary building at or below elevation 1025'. An extensive program was undertaken (in July) and was repeated as necessary during the months of August and September to blowdown air operated devices including air operated valves and to cycle those valves as allowed during power operatio After the trip of DG-2, the pilot valve was inspected and cleaned and the accumulator drained. Similar actions were taken for DG-1. To prevent a possible recurrence, an extensive corrective action program is in progres .

I_ ._ ____.____._____._________J

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merc pe.a. Je4A V 4 seUCtt& A A40U4Af 0AV Cohnere880se ,

'" * ' UCENSEE EVENT REPORT (LER) TEXT CONTINUATION a m ovioousno sisa-aiu

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At 0644 hours0.00745 days <br />0.179 hours <br />0.00106 weeks <br />2.45042e-4 months <br /> on September 22, 1987, when Fort Calhoun Station was operating at full power, Diesel Generator No. 1 (DG-1) was started to prove operability prior to performing maintenance on the exhaust pipe for Diesei Generator No. 2 (DG-2). At this time, a 7-day Limiting Condition for Operation was entered per Technical Specification 2.7. On September 23, 1987, at 0906 hours0.0105 days <br />0.252 hours <br />0.0015 weeks <br />3.44733e-4 months <br /> CDT, DG-2 was manually -

< started, followed by synchronization and loading at 0911 hours0.0105 days <br />0.253 hours <br />0.00151 weeks <br />3.466355e-4 months <br /> per Operating Instruction 01-DG-2 as required by Surveillance Test ST-ESF-6. At 0920 hours0.0106 days <br />0.256 hours <br />0.00152 weeks <br />3.5006e-4 months <br />, DG-2 automatically shutdown due to high coolant temperature. Personnel were immediately ,

dispatched to determine the cause of the overheating. Investigations revealed that the air operated radiator exhaust air damper YCV-871F may not have automatically fully opened when the diesel was running, thus restricting the required air flow through the radiator, and subsequently overheating the diesel coolan The air to operate the damper is supplied via a pilot valve. As shown on Figure 1, ,

the air to the pilot valve is provided by either the instrument air system or an accumulator. The damper is normally closed to limit the diesel's exposure to cold outside air and it is designed to be open when the diesel is runnin Investigations revealed that the pilot valve internals had a white, " lime-like" residue and the accumulator was partially filled with wate The pilot valve was cleaned, other associated valves and solenoids were inspected with no problems found, and the accumulator drained. The amount of water in the accumulator for DG-2 was not measured. It was approximately one-half full which represents two quarts of wate The cause of the damper malfunction was postulated to be the presence of the residue causing the pilot valve to sometimes stick. Since the potential existed for DG-1 to be similarly affected, the DG-1 exhaust dampers were cycled open without any problems and left open to ensure that if DG-1 was required to operate, adequate radiator cooling would be available. In accordance with the requirements of 50.73(a)(2)(vii), '

this event was determined to be reportable. DG-2 was successfully tested and returned to service at 1805 hours0.0209 days <br />0.501 hours <br />0.00298 weeks <br />6.868025e-4 months <br /> on September 2<, 1987. At this time, the Technical Specification 2.7 seven day Limiting Condition for Operation was exite Subsequently, DG-1 was removed from service and the instrument air valves associated l with the radiator exhaust damper were inspected and approximately 12 ounces of water was drained from the accumulato On July 6, 1987, during the performance of surveillance test ST-FP-5, operations personnel became aware that water had entered the instrument air system and immediately took actions to isolate the source of water intrusion, i.e., the instrument air connection to the diesel generator fire protection system dry pipe valve FP-513. The piping arrangement is shown on Figure Immediate corrective actions were to inspect and clean both check valves (IA-575 and

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IA-576) and to restore the diesel generator fire protection system. The extent of ,

the water in the air system was determined by blowing down selected air-operated components on the air risers. It was determined that water had not reached above

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elevation 1025'. This verified that no water entered containment since the i

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. centerline of the containment penetration. is located at elevation 1029'. No water was found in the instrument air system piping in the turbine building or the intake structure. An extensive program was undertaken to blow down the devices fed from the affected portions of the instrument air. system in the auxiliary building. Two groups were tasked with the verification of operability effort. - One group was . responsible for the accumulators and the other group was responsible for devices such as dampers, instruments and valve operators including solenoids and regulators. Of the 17 air accumulators reviewed for operability, 6 were above the 1025 elevation and did not require draining. Seven of the remaining 11 had no water and 4 had some water. As the result of a summary report issued to the Plant Review Committee on August 3,,1987, . five piston-operated air valves had required repair since July These valves were HCV-485, FCV-269X, HCV-2928, HCV-2918 and HCV-2882. The problems associated with these valves were not necessarily determined to be associated with'the instrument air system problem. A problem also existed with water in the bubbler that measures the diesel generator fuel storage tank. As allowed by procedure, an alternate method was used to verify tank level until the bubbler was repaire Currently, 38 valves have yet to be cycled because of operating constraints. The majority of these valves are diaphragm operated rather than piston operated. It has been concluded that failure of the operators for these valves would not j affect the plant's ability to mitigate the consequences of an accident or to 1 bring the plant to a safe shutdown conditio Corrective actions identified to date are as follow These actions are or will be completed: i Determine the connections between water and air system Specifically the interface between instrument air and the diesel generator fire protection system has been removed. Isolate the connection between the instrument air and Room 19 deluge valve. Tagged closed the instrument air connection to the water plant. Lock closed the connection between plant air and instrument air, CA-15 The interface between wet systems and instrument air via the bubbler used to measure tank level does not pose a hazard in 1 filling the instrument air system since they enter through the top of the J tank and the elevation of the bubbler is higher than the top of the tan ' Walk down the instrument air system to ensure that more connections to the instrument air system do not exis The walkdown is complete, No other similar wetted connections were foun . The blowdowns on the instrument air system devices located in the auxiliary  !

building below elevation 1025 have been repeate I I More frequent ISI tests on applicable systems, including stroke testing and l-verification by local observation the functioning of Critical Quality Element (CQE) valves. Quarterly tests will be performed monthly beginning with the November testing schedule until it has been determined that the quarterly schedule may be resume l

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Fort Calhoun Station, Unit N o s o o jo 21 8l5 Gi 7 0! 2l5 ,0;0 0;4 op, 0 5 run,, . - - w w .u.nin Stroke testing will also be performed on a selected sample of CQE valves not ircluded in the ISI program. The scope has been determined and the procedure is being prepare . The justification for continued operation for appropriate CQE valves that cannot be stroked during plant operation will be finalize . Ensure that the ISI valves that cannot be cycled during operation will be cycled during the next scheduled or forced cold shutdown in excess of 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> . Initiated a procedure change to MP-FP-7 to ensure check valves are inspected and are operable when the deluge valve is reset to ensure water does not enter the plant air system (plant air is a separate system from instrument air). Expedite a modification to permanently remove the tie between fire protection and the plant air syste . Initially revise the abnormal operating procedure A0P-17 on loss of instrument air to provide needed clarification Ensure A0P-17 adequately addresses system operation and rewrite it per the guidance contained in the writers guid . Implemen.t a dew point testing program and ensure operability of the air drye . For predictive maintenance purposes, inspect two non-CQE valves that had water problems to determine if degradation occurre . The investigation of events if the incident would have occurred during an actual diesel generator demand has been previously discusse . Ensure that the findings from the items above are reviewed by the Plant Review Committe A supplement to this LER is scheduled for submittal by December 15, 1987.

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