ML20085B436
| ML20085B436 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 07/29/1991 |
| From: | Wallace E TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 91-08, 91-8, NUDOCS 9108010189 | |
| Download: ML20085B436 (4) | |
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k Ten.wssee van y Amw% uot Mori wei cvuwvaa Tennesi.ee 374N e
JUL 291991 U.S. Nuclear Regulatory Conunission ATTN:
Document Control Desk Washington, D.C.
20555 Centlemen:
In the Matter of
)
Docket Nos. 50-327 Tennessee Valley Authority
)
50-328 SEQUOYAH NUCI. EAR PLANT (SQN) UNITS 1 AND 2 - DOCKET NOS. 50-327 AND 50-328 - FACILITY OPERATING LICENSES DPR-77 AND DpR SPECIAL REPORT 91-08. REVISION 1 The enclosed revised special report provides the updated cause of condition and corrective action concerning the inoperability of the fire suppression header, which supplies the emergency diesel generator building corridor sprinkler and hose stations. The revision also addresses the inoperability of Fire Doors D-7A and D-BA that were breached for greater than seven days in order to support routing of backup suppression to the affected area. The initial report was made in accordance with Technical Specification (TS) 3.7.11.1, Action Statement (b)(2)(c) on July 2, 1991. This revision is also being made in accordance with TS 3.7.12, Action Statement (a).
Revisions to tho special report are annotated by vertical bars in the right hand margin.
If you have any questions concerning this submittal, pleaco telephone James W. proffitt at (615) 843-6651.
Very truly yours.
TENNESSEE VALLEY AUTHORITY
, C. Wail a ae, Nuclea,.sLicensing an /
Regulatory Affairs i
Enclosure cc:
See page 2 l
5103010189 910729
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U.S Nuclear Regulatory Commiselon JUL 291981 cc (Enclosure):
Ms. S. C. Black, Deputy Director Project Directorate 11-4 U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockvillo, Maryland 20852 Mr. D. E. LaBarge, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 NRC Resident inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy-Daisy, Tennessee 37379 Mr. B. A. Wilson, Project Chief U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Coorgia 30323
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.e ENCLOSURC-SPECIAL REPORT 91-08, REVISION 1 Description of Condition On June 18,11991, at 1335 Eastern daylight time (EDT) with Units 1 and 2 operating at approximately 100 percent power, Limiting Conditions for
-Operation (LCOs) 3,7.11.1, 3.7.11.2, and 3.7.11.4 were entered.as a result of the fire header to the emergency diesel generctor building being removed from service.
The fire header was isolated because of an underground pipe rupture of the fire protection system.
This fire header is the supply to the diesel generator building corridor sprinkler and building hose stations.
Upon entering the LCOs, a backup fire suppression system was established by routing fire hoses from nearby hose stations to the affected areas, and fire watches were established for the affected areas. NRC was notified at 2145 EDT on June 18, 1991, as required by LCO 3.7.11.1, Action Statement b 2.a.
On June 1, 1991, at 0345 EDT, Operations' personnel had identified a leak from
' Fire Hydrant 0-26-886.- Upon investigation by Fire Operations' personnel, it was determined that because the hydrant would not open or close, the valve stem to the fire hydrant was not f unctioning properly.
The fire hydrant was
. isolated by closing fire hydrant Isolati.on Valve 0-26-534.
A work request to repair the hydrant and a Physical Security Instruction 13, Appendix C, " Fire l
Protection Program," were provided to document the identified problem.
Surveillance Instruction (SI) 0-SI-FPU-026-171.0, " Periodic Flushing and Chlorination of High-Pressure Fire Protection System," was being performed on June 18, 1991; and flushing of Fire Hydrant 0-26-886 was initiated.
The SI is performed once z very six months. The fire hydrant was placed in the full-open position with a discharge gated wye installed having a 2 1/2-inch valve partially open and fire hydrant Isolation Valve 0-26-534 closed.
The fire hydrant isolation valve was slowly opened. The water coming out of the gated wye began to cloud.with Valve 0-26-534 not fully opened.
Fire Operations' personnel observed a burst of dirty water followed by_a loud noise, which l
resulted in a loss of waterflow through the fire hydrant.
The fire hydrant-isolation valve was closed, and water was observed flowing from the' ground.
The header was immediately isolated by closing Valves 0-26-1618 and 0-26-683.
Operations' personnel entered LCOs 3.7.11.1, 3.7.11.2, and 3.7.11.4;-and appropriate actions were taken to comply with the requirements of the LCOs.
A' backup fire suppression system was established on June 18, 1991, which required breaching Fire Door D-8A.
Subsequently, an alternate backup ft"t suppression system was established on June 20, 1991, which required breaching L
Fire Door D-7A.
As a conservative measure, an additional fire hose was run to Ethe: diesel generator corridor hose station, which required Fire Door D-8A to remain breached.
Fire watches were maintained as required for the'affected areas in accordance with TSs - 3. 7.11.2 and 3. 7.12.
The fire header was returned-to service on July 16, 1991, at 1640 EDT; LCOs 3.7.11.1, 3.7.11.2, and 3.7.11.4 were exited'for this event on July l7, 1991, at 2233 EDT; and breaches for Fire Doors D-7A and D-8A were removed.
1-
. Cause of Condit19n
-A portion of six-inch fire protection system yard pipe that had been isolated and the fire hydrant were removed for analysis. The fire header contained a crack that was approximately 46 inches in length and ran JE_ ally along the bottom of the pipe.
The cracking of the pipe occurred when the fire hydrant valve suddenly closed.
An analysis of the valve stem of tho fire hydrant indicated that the safety stem coupling was damaged (broken) and decoupled the upper stem f rom the lower stem.
It could not be determined when or how the safety stem coupling was damaged.
It is considered that during the operation of the fire hydrant, it may_ have been over torqued, which could have caused the safety stem coupling to be damaged.
It is believed that this condition resulted in the the fire hydrant valve becoming loose and acting as a " check valve."
It is concluded that the loud noise that the Fire Operations' personnel heard was the fire hydrant valve suddenly slamming closed, which was caused by the flow of water striking the bottom of the lower valve plate and t e cracking of the pipe.
The valve was free-to move because of the damaged.rass safety stem coupling.
The sudden closure of the fire hydrant valve resulted in a water Tammer that exerted sufficient force to crack the pipe.
I Corrective Action Immediate corrective action was taken to stop the leak by isolating the fire l
protection header to the emergency diesel generator building and complying I
with the LCO action, which requires backup fire suppression and the establishment of a fire wttch for the affected aren.
NRC was notified of this i
condition at 2145 EDT on Jute 18, 1991, followed by a facsimile dated June 19, 1991.
l Tha appropriate portions of the fire protection header and fire hydrant have been removed, analyzed, and repaired and/or replaced.
The fire header to the emergency diesel generator building and Fire Doors D-7A and D-8A have been returned to normal service.
As a result of.the damage to the safety stem coupling from potential overtorquing, a site dispatch was issued stating that Physical Security Instruction (PHYSI) 13. " Fire Protection Program," was being revised to prohibit personnel other than Fire Operations,- Operations, or persons approved -
by the Operations organization from operating fire protection equipment.
In addition, the dispatch stated that any manipulation of fire protection-equipment, except during-emergencies, must have the shift operations supervisor or the Fire Operations foreman's authorization.
PHYSI-13 will be revised by. September 6, 1991, to include the above conditions for the operation and manipulation of the fire protection system.
C l'
Commitment l
[.
TVA will revise PHYSI-13 to prohibit personnel other than Fire Operations, j
Operations, or persons approved by the Operations organization from operating the fire protection system by September 6, 1991.
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