ML20236R911
| ML20236R911 | |
| Person / Time | |
|---|---|
| Issue date: | 07/08/1998 |
| From: | Stolz J NRC (Affiliation Not Assigned) |
| To: | Roe J NRC (Affiliation Not Assigned) |
| References | |
| 98-005, OREM-98-5, NUDOCS 9807240009 | |
| Download: ML20236R911 (17) | |
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July 8,1998 MEMORANDUM TO: Jack W. Roe, Acting Director Division of Reactor Program Management FROM:
Jo n to$
ik Events Assessment and Generic Communications Branch Division of Reactor Program Management
SUBJECT:
OPERATING REACTORS EVENTS BRIEFING July 1,1998 - BRIEFING 98-05 On July 1,1998, we conducted an Operating Reactors Events Briefing (98-05) to inform senior managers from the Offices of the Commission, EDO, AEOD, NRR and regional offices of 1
selected events that occurred since our last briefing on May 20,1998. Attachment 1 lists the atteAdees. Attachment 2 presents the significant elements of the discussed event.
I The statements contained in the attached briefing slides represent the best information j
currently available to the NRC. Future followup could produce new information that may alter the NRC's current view of the event discussed.
Attachments:
- 1. List of attendees
- 2. Briefing slides
- 3. Preliminary WNP2 Risk Assessment
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See next page CONTACT: Beverly Sweeney, NRR
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(301) 415-1166
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l S. Collins, NRR (0-12G18)
W. Bateman (0-13E16) i F. Miraglia, NRR (0-12G18)
C. Poslusny (0-13E16) l F. Gillespie, NRR (0-12G18)
B. Boger, NRR (0-14E4)
B. Sheron, NRR (0-12G18)
J. Zwolinski, NRR (0-14H3)
E. Adensam, NRR (0-13E4)
G. Lainas, NRR (0-7D26)
G. Holahan, NRR (0-8E2)
D. O'Neal, NRR (0-10E4)
L. Spessard, NRR (0-9E4)
M. Markley, ACRS (T-2E26)
T. Martin, AEOD (T-4D18)
C. Rossi, AEOD (T-4A9)
F. Congel, AEOD (T-4D28)
R. Barrett, AEOD (T-4A43)
S. Rubin, AEOD (T-4D28)
M. Harper, AEOD (T-4A9)
W. Leschek, AEOD (T-4A9)
G. Tracy EDO (0-16E15)
J. Gilliland, PA (0-2G4)
D. Morrison, RES (T-10F12)
W. Hill, SECY (0-16G15)
H. Miller, Region i C. Hehl, Region i L. Reyes, Region ll L. Plisco, Region ll S. Vias, Region 11 J. Caldwell, Region lli G. Grant, Region lli E. Mershoff, Region IV P. Gwynn, Region IV K. Perkins, Region IV/WCFO G. Fader, INPO J. Zimmer, DOE 1
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i LIST OF ATTEND ES OPERATING REACTORS EVENTS FULL BRIEFING (98-05) l i
l July 1,1998 l
l NAME OFFICE BLAME OFFICE C. Petrone NRR F. Brown OCM/SJ B.Sweeney NRR S. Newberry NRR J. Stolz NRR G. Hubbard NRR T.Koshy NRR L. B. Marsh NRR l
C. E. Rossi AEOD M. H. Salley NRR W. Bateman NRR K. S. West NRR P. Wilson NRR P. Qualls NRR D. Jackson NRR D. Skeen NRR J. Beall OCM/EM A. El-Bassioni NRR G. Hubbard NRR D. Terao NRR l
P. Castleman OCM/NJD E. Adensam NRR P. Kang NRR l
TELEPHONE ATTENDANCE (AT ROLL CALL)
Reaions Resident insoectors Region I Region il Region ill 1
Mian.
J. Skakelford, AIT Team Leader D. Chamberlain, RIV T. P. Gwynn, RIV ATTACHMENT 1
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98-05 l
OPERATING REACTORS EVENTS BRIEFING 98-05 J
LOCATION: 0-12B4, WHITE FLINT WEDNESDAY, JULY 1,1998,11:00 A.M.
WASHINGTON NUCLEAR 2 (WNP-2)
FLOODING OF ECCS PUMP ROOMS CAUSED BY FIRE WATER SYSTEM VALVE RUPTURE PRESENTED BY:
EVENTS ASSESSMENT, GENERIC COMMUNICATIONS AND SPECIAL INSPECTION BRANCH DIVISION OF REACTOR PROGRAM MANAGEMENT, NRR
98-05 l
WASHINGTON NUCLEAR 2 (WNP-2) l FLOODING OF ECCS PUMP ROOMS CAUSED BY FIRE WATER SYSTEM VALVE RUPTURE JUNE 17,1998 PROBLEM O
RUPTURE OF A FIRE PROTECTION SYSTEM l
HEADER VALVE IN THE NORTHEAST STAIRWELL OF THE REACTOR BUILDING CAUSED FLOODING OF THE RESIDUAL HEAT REMOVAL (RHR) PUMP ROOM C AND THE ADJACENT LOW PRESSURE CORE SPRAY (LPCS) PUMP ROOM.
SAFETY SIGNIFICANCE l
O TWO ECCS SYSTEM TRAINS, RHR C AND LPCS, AND THE FIRE PROTECTION SYSTEM WERE RENDERED INOPERABLE. ADDITIONALLY, THE i
KEEPFILL PUMPS FOR THE OTHER LOW PRESSURE ECCS TRAINS, RHR-A AND RHR-B WERE SUBMERGED AND RENDERED INOPERABLE. THE LICENSEE DECLARED AN UNUSUAL EVENT.
CONTACT:
C. PETRONE, NRR/DRPMIPECB AIT: YES
REFERENCE:
10 CFR 50.72 #34408; SIGEVENT: YES i
PNO-4-98-025,025A, & 025B l
l WNP-2 98-05 CAUSE O
FAILURE OF FIRE VALVE DUE TO WATER HAMMER. THIS WATER HAMMER WAS PROBABLY DUE TO THE SYSTEM DESIGN DEFICIENCIES WHICH INCLUDED LONG HORIZONTAL RUNS OF PIPING AND A COLUMN OF WATER L
180' HIGH IN THE RISERS IN THE REACTOR BUILDING.
PLANT CONDITION O
AT THE TIME OF THE EVENT, APPROXIMATELY 1:45 P.M. ON l
JUNE 17,1998, THE REACTOR WAS SHUT DOWN IN MODE 4 WITH THE REACTOR COOLANT SYSTEM AT 133 DEGREES F.
i DISCUSSION r
SEQUENCE OF EVENTS:
i O
AT 1:45 P.M. - MULTIPLE FIRE ALARMS ANNUNCIATED IN THE CONTROL ROOM, AN AUTO START OF ALL 4 FIRE PUMPS OCCURRED AND SEVERAL LOUD WATER HAMMER NOISES WERE HEARD IN THE CONTROL ROOM AND THROUGHOUT THE PLANT.
O RUPTURE OF A FIRE PROTECT!ON SYSTEM HEADER VALVE FLOODED THE NORTHEAST STAIRWELL OF THE REACTOR BUILDING TO A DEPTH OF 19 FEET.
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WNP-2 98-05 O
WATER FROM THE STAIRWELL ENTERED RHR PUMP ROOM C AND EVENTUALLY SUBMERGED THE PUMP MOTOR AS WELL AS THE KEEPFILL PUMP FOR THE RHR BIC TRAINS.
O WATER FROM RHR "C" PUMP ROOM ALSO FLOWED INTO THE ADJACENT LPCS PUMP ROOM AND FLOODED IT TO 1 FOOT BELOW THE BASE OF THE LPCS PUMP MOTOR. THE KEEPFILL PUMP FOR THE RHR-A/LPCS TRAINS WAS SUBMERGED.
EVALUATION THE INITIAL EVALUATION BY THE LICENSEE AND THE NRC INDICATED THAT:
O THE EVENT WAS INITIATED BY THE ACTUATION OF A FIRE DETECTOR DURING CUTTING AND GRINDING ACTIVITIES IN THE DIESEL GENERATOR BUILDING. THE ASSOCIATED l
PRE-ACTION VALVES (DELUGE) OPENED TO FILL THE l
NORMALLY DRY SPRINKLER LINE HEADER IN THE EDG i
ROOM. NO ACTUATION OF THE ASSOCIATED SPRINKLERS OCCURRED. (TWO SEPARATE PREACTION SYSTEMS l
ACTUATED. ONLY ONE OF THE PREACTIONS WAS AN EXPECTED SYSTEM RESPONSE.)
l WNP-2 4-98-05 O
THE FILLING OF THE SPRINKLER HEADERS IN THE EDG ROOM CAUSED A MOMENTARY DEPRESSURIZATION OF THE FIRE WATER SYSTEM WHICH DREW DOWN THE l
WATER LEVEL IN THE NORMALLY WET FIRE MAIN RISERS.
l THIS RESULTED IN A VOID IN THE TOP OF THE FIRE MAIN 3
l RISERS. THE SUBSEQUENT STARTUP OF ALL FOUR FIRE WATER PUMPS RAPIDLY REPRESSURIZED THE SYSTEM INCLUDING THE FIRE MAIN RISERS IN THE REACTOR BUILDING. THIS REPRESSURIZATION CAUSED A WATER j
HAMMER WHICH RUPTURED THE FIRE MAIN RISER ISOLATION VALVE IN THE STAIRWELL.
i O
REVIEW OF THE MAINTENANCE HISTORY OF THE VALVE l
DID NOT IDENTIFY ANY DEFICIENCIES THAT WOULD INDICATE THE VALVE WAS DEFECTIVE.
O WATER FROM THE STAIRWELL ENTERED RHR PUMP ROOM C THROUGH AN UNSECURED /OPEN WATERTIGHT DOOR AND EVENTUALLY SUBMERGED THE RHR C PUMP MOTOR AND THE RHR B AND C KEEPFILL PUMP. IT IS UNKNOWN WHY THE DOOR WAS LEFT UNSECURED /OPEN. HOWEVER, BECAUSE OF THE SINGLE WATERPROOF DOOR DESIGN, THE DOOR IS ASSUMED TO LEAK AT A RATE OF APPROXIMATELY 70 GPM EVEN WHEN CLOSED.
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WNP-2 98-05 9
WATER FROM THE RHR C PUMP ROOM ENTERED THE LPCS PUMP ROOM THROUGH THE FLOOR DRAIN SYSTEM.
A VALVE IN THE FLOOR DRAIN SYSTEM THAT SHOULD HAVE ISOLATED THE ROOMS FAILED TO CLOSE. THIS VALVE, WHICH PROVIDES SINGLE ISOLATION BETWEEN THE TWO ROOMS, HAD BEEN IDENTIFIED AS DEFICIENT SEVERAL MONTHS EARLIER. DUE TO INCONSISTENCIES BETWEEN THE FSAR/ FLOODING ANALYSIS /SER IT IS UNCLEAR WHETHER THERE SHOULD HAVE BEEN DOUBLE VALVE ISOLATION. THIS VALVE WAS NOT IN THE SCOPE OF THE MAINTENANCE RULE OR ANY OTHER MAINTENANCE / TESTING PROGRAM. A SIMILAR CONFIGURATION EXISTS WITH RESPECT TO THE RHR-l AIRCIC SUMP AND THE HPCS/CRD SUMP.
O THE DOUBLE WATER TIGHT DOORS BETWEEN THE LPCS AND HPCS PUMP ROOMS, AS WELL AS BETWEEN THE RHR C PUMP ROOM AND THE REACTOR CORE ISOLATION COOLING (RCIC) PUMP ROOM DID NOT COMPLETELY SEAL AND ALLOWED FOR MINOR WATER INTRUSION.
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WNP-2 98-05 LICENSEE IMMEDIATE CORRECTIVE ACTIONS O
THE LICENSEE SECURED THE RUNNING FIRE PUMPS, ACTIVATED THE TECHNICAL SUPPORT CENTER AND i
OPERATIONS SUPPORT CENTER AND DECLARED AN UNUSUAL EVENT.
l O
AFTER SAMP. LING FOR CONTAMINATION, THE LICENSEE i
BEGAN PUMPING WATER FROM THE FLOODED AREAS TO i
A STORM DRAIN OUTSIDE OF THE REACTOR BUILDING THEN SWITCHED THE DISCHARGE TO AN ALTERNATE l
SUMP WHEN LOW LEVELS OF RADIOACTIVITY WERE DETECTED.
O TO COMPENSATE FOR FIRE PROTECTION SYSTEM DEGRADATION, THE HANFORD FIRE DEPARTMENT RESPONDED TO THE SITE WITH TWO FIRE ENGINE l
PUMPER TRUCKS, TWO 5000 GALLON FIRE TENDER TRUCKS, AND TWO COMPLETE CREWS.
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WNP-2 98-05 O
THE FIRE PROTECTION SYSTEM WAS RETURNED TO j
OPERABLE (BUT DEGRADED) STATUS WITH THE PRE-ACTION LINES DRY. TO HELP PREVENT FUTURE WATER HAMMER EVENTS, TWO FIRE PUMPS WERE PLACED IN SERVICE TO KEEP THE FIRE MAIN RISERS PRESSURIZED IN THE EVENT ANY FUTURE FIRE DETECTION INITIATION RESULTS IN ANOTHER PRE-ACTION FILLING OF THE DRY I
SPRINKLER HEADERS.
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l O
A FORMAL ROOT CAUSE TEAM WAS ESTABLISHED TO l
l INVESTIGATE THE EVENT.
I O
THE LICENSEE COMMITTED TO PROVIDE RIV WITH A l
WRITTEN CHARTER AND ROOT CAUSE PLAN FOR l
RECOVERY PRIOR TO RESTART. THEY WILL BE BRIEFING RIV AT 9:00 AM ON JULY 2; IT WILL BE ON VIDEO CONFERENCE.
I LICENSEE LONG-TERM CORRECTIVE ACTION O
INSPECT ALL COMPONENTS THAT MAY BEEN AFFECTED BY THE FLOODING.
O OVERHAUL RHR-C PUMP MOTOR (COMPLETED) l i
l I
WNP-2 98-05 I
O INVESTIGATE POSSIBLE CAUSES OF THE VALVE FAILURE INCLUDING WATER HAMMER AND PROPOSE CORRECTIVE MODIFICATIONS i
O DETERMINE IF FLOODING ANALYSIS IS ADEQUATE j
O DETERMINE IF FLOOR DRAIN VALVES AND DOOR SEALS l
ARE ADEQUATE NRC FOLLOWUP O
THE SENIOR RESIDENT INSPECTOR RESPONDED TO THE l
EVENT.
O THE REGION IV INCIDENT RESPONSE CENTER WAS ACTIVATED TO MONITOR THE EVENT.
O THE HEADQUARTERS INCIDENT RESPONSE CENTER WAS l
ALSO ACTIVATED FOR TWO DAYS AND SUPPORTED BY NRR PROJECTS AND TECHNICAL STAFF O
A SENIOR PROJECT ENGINEER FROM THE WALNUT CREEK FIELD OFFICE WAS ONSITE AT THE TIME OF THE EVENT AND PROMPTLY RESPONDED TO THE CONTROL ROOM.
WNP-2 98-05 O
AN ADDITIONAL INSPECTOR WAS DISPATCHED TO THE SITE TO HELP PROVIDE 24-HOUR COVERAGE OF LICENSEE RESPONSE AND RECOVERY OPERATIONS.
O AN AUGMENTED INSPECTION TEAM LED BY JEFF l
SHACKELFORD ARRIVED ONSITE JUNE 19 AND DEBRIEFED ON JUNE 24.
I O
ANOTHER INSPECTION TEAM IS CURRENTLY ONSITE TO REVIEW LICENSEE ACTIVITIES O
NRC REGION IV BRIEFED FEMA REGION X AND THE STATE OF WASHINGTON ON THE EVENT.
O REGION IV WILL REVIEW THE LICENSEE'S WRITTEN CHARTER AND ROOT CAUSE PLAN PRIOR TO RESTART.
l O
A PRELIMINARY RISK ASSESSMENT BY NRR STAFF IS l
ATTACHED.
O INFORMATION NOTICE WILL BE ISSUED TO DISCUSS THIS EVENT.
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Washington ficlear 2 1
Briefing 98-05 i
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hhington ticlear 2 Briefing 98-05 1
1 Preliminary WNP2 Risk Assessment The risk associated with the actual event is not easily quantifiable due to the nature of e
the event and the capabilities of the NRC's risk assessment tools.
l From a qualitative perspective the risk associated this event is minimal. The following is l
e the basis for this preliminary assessment.
l There was no actual fire in the plant. Therefore, the effects from an actual fire did not have to be considered.
The time that the plant was without water to suppress fires was limited to approximately 30 minutes.
1 No demand for accident mitigation equipment to start.
l The amount of core decay heat was not significant (time to boiling > 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />).
There were several sources from which water could be injected for core cooling.
O RHR pumps'A & B O
HPCS D
3 condensate pumps
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l The event would have had more significance had occurred at power. However, since the e
j event and loss of the associated equipment would not cause a plant shutdown, the risk associated with the loss of RHR-C and LPCS trains alone would still be small.
l The possibility of an unrelated fire following the observed event coupled with the loss of e
3 the RHR-C, the LPCS pump, and the fire suppression system.
J The plant would trip (or be tripped) due to the unrelated fire i
Fire event must be mitigated without the RHR-C, LPCS, and fire suppression I
j The conditional core damage probability for this scenario was also small (1E 6).
Preliminary Risk Assessment did not include consideration of the following:
Potential common cause failure of the fire protection actuation system during actual fires that would result in sufficient water hammer to cause valve failure Potential common cause failure of other fire main valves and the resulting infomal flooding Potential impact of the loss of the keep fill pumps Potential electrical faults resulting from the intemal flood
_ _ _ _ _ _