ML20077L481
| ML20077L481 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 08/05/1991 |
| From: | Joshua Wilson TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 91-12, NUDOCS 9108120270 | |
| Download: ML20077L481 (4) | |
Text
o IUA i-J,a t W m i
August 5, 1991 U.S. Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of
)
Docket Nos. 50-327 Tennessee Valley Authority
)
50-328 SEQUOYAH NUCLEAR PLANT (SQN) - TECHNICAL SPECIFICATION 3.7.11.1 - SPECI AL REPORT 91-12 The enclosed special report provides details concerning the inoperability of the backup fire suppressicn water system.
The event was initially reported by telephone notification at 1533 Eastern daylight time on July 23, 1991, and by facsimile dated July 23, 1991.
Because the event involves the fire suppression water system, it is applicable to Units 1 and 2.
This report is being nede in accordance with Action b.2.c of
^
Technical Specification 3.7.11.1.
If you have any questions concerning this submittal, please telephone R. R. Thompson at (615) 843-7470.
Very truly yours, TENNESSEE VALLEY AUTHORITY L Sn^-
L. Wilson Enclosure cc:
See page 2 910812O270 910805 ppR ADOCK 0500 i7
'/<
(
l i
i 2
t U.S. Nuclear Regulatory Conclssion August 5. 1991 i
cc (Enclosure):
i Mr. D.
F., LaBarge, Project Manager U.S. Nuclear Regulatory Commission One White Filnt, North 11555 Rockville Pike Rockville, Maryland 00852 NRC Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road e
Seddy-Daisy. Tennessee 37379 Mr. B. A. Wilson, Project Chief U.S. Nuclear Regulatory Comrnission i
Region II 101 Marietta Street. NW, Suite 2900 Atlanta Georgia 30323 l
I e
r n
b w
w
,e-
~,w, w,,-,, -,,,
v-w--,,,,-n.
,n-,vn,,,,..-,-,,,7,,,wm,--,---,,,,w.,,,w.mm-e-w,--,-m.wamea--,wn,
.,---s.c
,,.,,.g-,.,
p,y,gw-+-g
-.,er,n,-we---
\\
ENCLOSURE 14-DAY FOLLOW-UP REPORT SEQUOYAH NUCLEAR PLANT SPECIAL REPORT 91-12 Description of Condition Technical Specification 3.7.11.1 requires the fire suppression water system to be operable at all times. With the system inopetable, a backup system must be established within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
Prior to this event, the SQN fire suppression water system had been declared inoperable, and a bat.kup system utt11r.ing the exis'.ing system components had been established on May 6, 1991.
Details were provided in Special Report 91-04 dated May 20, 1991, and Licensee Event Report i
(LER) 50-327/91009 dated June 5, 1991.
During the performance of Surveillance Instruction (SI) 73.2, " Fire Pump 1B-B Performance Test," and St-73.4, " Fire Punt 2B-B Performance Test," on l
. July 22, 1991, an incorrect valve alignment created an open flow path from the 4
iiro suppression water system headers to a test drain, which discharges into j
the intake forebay. Consequently,: header pressure for the backup fire suppression water system was lost, and the backup system was declared inoperabic at 2115 Eastern daylight time (EDT) on July 22, 1991.
Because of the lack of system pressure, the spray and sprinkler systems required by Limiting condition for Operation (LCO) 3.7.11.2, and the ftre hose stations requited by LCO 3,7.11.4 were also declared inoperable at 2115 EDT on July 22.
i The gradual loss of system pressure was first noted at approximately 1800 EDT on,iuly 22.
Efforts were initinted to locate and isolate the cause of the l
depressurization.
The shift operations supervisor (505) contacted the Fire Operations unit and the fire protection system engineer to evaluate compensatory measures and to develop a recovery plan. The status of the firo pump test loop isolation valve was checked.- The valve was found to be in the open position at 2140 EDT, and was subsequently closed as p rt of the recovery plan.
Isolation of.the turbine bu11 ding and transformer yard open head sprinkler systems was completed at 2225 EDT to prevent the inadvertent spraying down of plant equipment as the system was being returned to normal. At 2302 EDT a 1
pumper-fire truck was used a heein system repressuriration. At 0129 EDT on i
July 23. system pressure had been returned to normal, and the fire suppression water system was aligned for normal servico.
LCOs 3.7.11.2 and 3.7.11.L were
?
exited at this-time, i
Cause of the Condition l
l.
The flow-path-from-the: fire suppression water system to the intake forebay was the-result of_ Valves 2-26-575 and 0-26-859 (refer to Updated Final Safety Analysis Report, figure 9.5.1-12) being incorrectly aligned in the r, pen position at the same time.
The cause of the incorrect valve _ alignment is attributed to inappropriate personnel actions.
-. Investigation into the root cause of the event is ongoing and will be reported in LER 50-327/91020.
_ _ _.a _ _-.._._,. _.. _. _ _ _,, _ _ _.._ _ _. - - - - ~,
i
_2 4
l A,_najysis of' Condition l
The evaluation of this condition is ongoing and will be reported in LER 50-327/91020.
Corrective Action l
t l'pon di.scovery of the condition, actions were taken to locate and isolate the
- problem. When it was determined that system pressure was not availablo, LCOs 3.7.11.2 and 3.7.11.4 were entered. Actions began to isolate the turbine building atA transformer yard open head sprinkler systems to prevent inadvertent 3 pray down of plant equipment upon the system being returned to service. A review of compensatory actions indicated that the rivallable established fits watches, in conjunction with detectica and i
compartmentalizaeten, were appropriate during system return to service.
The r
- incorrect valve alignment was corrected, and a pumper was utilized to begin system repressurization following isolation of the turbine building and i
transformer yard sprinkler systems. The system was returned to normal at-0129 EDT on July 23, 1991.
)
Corrective actions to prevent recurrence are being developed and will be described in LER $0-327/91020.
12 6
1 i
l
[
l f
i l
E t
rgpt-e-y
.f, y
is s.auy w
4 4
a,4 gma+-
ery.wmr
,s,enant--
sy ke9y-,,yg%.,wm+dmtW,v.%.qgye-.a,t'-re'=1**7
.N=W=4u NT-'M-4NN Tm w h-m h ezu r w ' yg wt4
'P rmr w g o.w g y yW u ree 'yey1 g)vgg Tr we 'wr V7' y wy'-
-