PNO-IV-97-026A, on 970507,shutdown Greater than 72 H After Manual Scram Update Made.Workers Removing Fire Seal Matl from Penetration in Turbine Bldg to Run Addl Cable Through Penetration in Accordance W/Authorized Station Mod
| ML20148A532 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 05/08/1997 |
| From: | Harrell P, Will Smith NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| References | |
| PNO-IV-97-026A, PNO-IV-97-26A, NUDOCS 9705090037 | |
| Download: ML20148A532 (2) | |
-
s
. May 8,1997 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO-IV-97-026A This preliminary notification constituin EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by Region IV staff in Arlington, Texas on this date.
Facility Licensee Emeraency Classification Entergy Operations, Inc.
X Notification of Unusual Event River Bend 1 Alert St Francisville, Louisiana Site Area Emergency Dockets: 50-458 General Emergency Not Applicable
Subject:
SHUTDOWN GREATER THAN 72 HOURS AFTER MANUAL SCRAM - UPDATE On May 6,1997 at 9:02 a.m. (CDT), while operating at 99 percent power, the 13.8-kV noncafety-related Bus B and the 4.16-kV safety-related Bus B lost power. This resulted in a loss of 2 of the 3 motor driven feedwater pumps and the B reactor recirculating pump.
Tha operators immediately manually scrammed the reactor. The reactor shut down and the main turbine tripped per design. Because Reactor Protection System B power was lost also, required systems were isolated, including cooling water to the reactor recirculating pumps. The operators secured Reactor Recirculating Pump A, which initiated natural circulation. All ESF systems responded in accordance with their intended design functions. By 11 a.m. (CDT) the plant was stable and in a normal hot shutdown status.
The following is an update on this event.
At 4:52 p.m. (CDT), the licensee completed an inspection of the drywell for a 2 gpm unidentified leak that had existed for some time and identified a packing leak on inboard main steam isolation Valve B. The licensee also identified a cracked socket weld on the 3/4-inch vent valve welded to the upper body of Reactor Flow Control Valve B. The crack was on the weld attaching the vent valve to the pipe nipple, which in turn was welded to the flow control valve. The crack appeared to be 180 degrees around the circumference of the vent valve to pipe nipple weld. At 8:10 p.m. (CDT), the licensee reported the cracked weld to the NRC Operations Officer as a nonisolable leak on the reactor recirculation system and entered the Technical Specification LCO, which required placing the plant in Mode 4 (Cold Shutdown) in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
At approximately 8:15 a.m. (CDT) on May 7, the resident inspectors questioned why the licensee had not declared a Notification of Unusual Event (NOUE) upon entering the Technical Specification LCO for pressure boundary leakage, as required by the licensee's emergency plan implementing procedure. At 9 a.m. (CDT) on May 7, the licensee declared a NOUE in accordance with the procedure, on the basis that the Technical Specification LCO for pressure boundary leakage was in effect while in Mode 3 (Hot Shutdown). The reactor was at approximately 265 degrees F at the time of the NOUE declaration and the operators were in the process of placing shutdown cooling in service. The NOUE was exited at 1:44 p.m. (CDT), when the plant entered Mode 4.
S o\\
D 9705090037 970508 k
b\\
PDR I&E PNO-IV-97-026A PDR 00007i
PNO-IV-97-026A The cause of the loss of onsite power was determined to be workers that short circuited and severed the control cable for the 86-1R2 and 86-2R2 protective lockout relays, which j
in turn by design, tripped the three breakers supplying offsite power to the 13.8-kV i
nonsafety-related Bus B, the 4.16-kV safety-related Bus B, and two 4.16-kV l
nonsafety-related Buses, one of which supplied power to the safety-related high pressure core spray bus. The workers were removing fire seat material from a penetration in the turbine building to run additional cable through the penetration in accordance with an authorized station modification.
)
1 The state of Louisiana will be informed.
j 4
Region IV received this update by telephone from the Senior Resident inspector at 9:05
)
a.m. (CDT), on May 7,1997. Region IV has informed EDO, NRR, and PA.
l This information has been discussed with the licensee and is current as of 3:15 p.m.
d (CDT), on May 7,1997.
4
Contact:
P. H. Harrell Ward Smith
]
(817)860-8250 (504)635-3193
\\
i-1 l
)
i 1
1