Event Notification Report for May 12, 2002
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
05/11/2002 - 05/12/2002
EVENT NUMBERS
38915
Power Reactor
Event Number: 38915
Facility: COOK
Region: 3 State: MI
Unit: [] [2] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: BRADDOCK D. LEWIS
HQ OPS Officer: LEIGH TROCINE
Region: 3 State: MI
Unit: [] [2] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: BRADDOCK D. LEWIS
HQ OPS Officer: LEIGH TROCINE
Notification Date: 05/13/2002
Notification Time: 02:39 [ET]
Event Date: 05/12/2002
Event Time: 23:01 [EDT]
Last Update Date: 05/14/2002
Notification Time: 02:39 [ET]
Event Date: 05/12/2002
Event Time: 23:01 [EDT]
Last Update Date: 05/14/2002
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL
Person (Organization):
ANTON VEGEL (R3)
ANTON VEGEL (R3)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | A/R | Y | 100 | Power Operation | 0 | Hot Standby |
AUTOMATIC REACTOR TRIP DUE TO AN INSTRUMENTATION RACK POWER SUPPLY FAILURE WHICH CAUSED A STEAM GENERATOR FEEDWATER REGULATING VALVE TO FAIL CLOSED
The following text is a portion of a facsimile received from the licensee:
"DC Cook Unit 2 tripped from full power due to an instrumentation rack power supply failure on 05/12/02 [at] 2301. All control rods fully inserted. No Safety Injection was required. The Unit 2 Reactor is stable and subcritical. The Steam Generator Stop Valves were manually closed by the Operating Crew to stabilize RCS Temperature in accordance with Plant operating procedures. Reactor Coolant Temperature is being maintained manually on the Steam Generator Atmospheric relief valves at No-Load T(ave) in accordance with plant procedures."
"This instrumentation rack power supply failure caused the #21 Steam Generator Feed Regulating Valve to fail CLOSED. The Unit 2 Reactor subsequently TRIPPED on Low Level in [the] #21 Steam Generator coincident with Low Feedwater Flow. Several control systems were affected by the control rack instrumentation failure: Pressurizer Pressure Control - transferred control to manual and restored Pressurizer pressure, Pressurizer Level Control - transferred control to manual and restored Pressurizer water level, Refueling Water Sequence - Manually transferred Charging Pump Suction to the RWST. Manual Operator response maintained and restored critical plant parameters in MANUAL to normal parameter values."
"Unit 2 entered Technical Specification 3.0.3 for 34 minutes because the control system failures and plant system response temporarily caused the Boration Flow paths from both the Refueling Water Storage Tank and Boric Acid Storage Tanks to become INOPERABLE. Both Boration flow paths were subsequently returned to OPERABLE status by manual Operator action."
"The Reactor trip is reportable in accordance with 10 CFR 50.72(b)(2)(iv)(B) as an actuation of the Reactor Protection System (RPS) when the Reactor was critical. The Reactor TRIP was the result of an instrumentation rack power supply failure and was not part of any preplanned test or evolution."
The licensee stated that the unit is currently stable in Mode 3 (Hot Standby). The reactor coolant pumps are available for primary system transport control. Pressurizer level and pressure control are in manual. Normal charging and makeup are available, but the automatic function of the refueling water sequence is not available. The auxiliary feedwater pumps automatically started as expected and are currently being utilized to supply water to the steam generators. Secondary steam is being dumped to atmosphere. There is no evidence of steam generator tube leakage, and containment parameters are as expected. There were no safety injections and none were required, and none of the primary power-operated relief valves lifted.
The licensee notified the NRC resident inspector.
****UPDATE 5/14/02 At 13:20 From B. Bates To R. Laura****
The initial report stated that the reactor coolant temperature is being maintained manually on the steam generator atmospheric relief valves at no-load Tave in accordance with plant procedures. Temperature control was actually established in automatic on the steam generator atmospheric relief valves and remains in automatic.
A statement was made in the original report that Unit 2 entered Technical Specification 3.0.3 for 34 minutes. Upon further review, there was no requirement to enter Technical Specification 3.0.3. The control system failures and plant system response caused the boration flowpaths from both the Refueling Water Storage Tank (RWST) and Boric Acid Storage Tanks to become inoperable. Therefore, the Unit was actually in Technical Specification 3.1.2.2 actions (a)and (b) concurrently. This did not constitute an entry into Technical Specification 3.0.3 because entry into both actions is not prohibited.
Another statement was made that both boration fiowpaths were subsequently returned to operable status by manual operator action. The boration flowpath from the boric acid storage tanks was returned to operable. However, after further investigation, it was determined that the boration flow path from the RWST remained inoperable due to the inability of the refueling water sequence to automatically initiate. The NRC Resident Inspector was notified.
Notified R3DO R. Gardner.
The following text is a portion of a facsimile received from the licensee:
"DC Cook Unit 2 tripped from full power due to an instrumentation rack power supply failure on 05/12/02 [at] 2301. All control rods fully inserted. No Safety Injection was required. The Unit 2 Reactor is stable and subcritical. The Steam Generator Stop Valves were manually closed by the Operating Crew to stabilize RCS Temperature in accordance with Plant operating procedures. Reactor Coolant Temperature is being maintained manually on the Steam Generator Atmospheric relief valves at No-Load T(ave) in accordance with plant procedures."
"This instrumentation rack power supply failure caused the #21 Steam Generator Feed Regulating Valve to fail CLOSED. The Unit 2 Reactor subsequently TRIPPED on Low Level in [the] #21 Steam Generator coincident with Low Feedwater Flow. Several control systems were affected by the control rack instrumentation failure: Pressurizer Pressure Control - transferred control to manual and restored Pressurizer pressure, Pressurizer Level Control - transferred control to manual and restored Pressurizer water level, Refueling Water Sequence - Manually transferred Charging Pump Suction to the RWST. Manual Operator response maintained and restored critical plant parameters in MANUAL to normal parameter values."
"Unit 2 entered Technical Specification 3.0.3 for 34 minutes because the control system failures and plant system response temporarily caused the Boration Flow paths from both the Refueling Water Storage Tank and Boric Acid Storage Tanks to become INOPERABLE. Both Boration flow paths were subsequently returned to OPERABLE status by manual Operator action."
"The Reactor trip is reportable in accordance with 10 CFR 50.72(b)(2)(iv)(B) as an actuation of the Reactor Protection System (RPS) when the Reactor was critical. The Reactor TRIP was the result of an instrumentation rack power supply failure and was not part of any preplanned test or evolution."
The licensee stated that the unit is currently stable in Mode 3 (Hot Standby). The reactor coolant pumps are available for primary system transport control. Pressurizer level and pressure control are in manual. Normal charging and makeup are available, but the automatic function of the refueling water sequence is not available. The auxiliary feedwater pumps automatically started as expected and are currently being utilized to supply water to the steam generators. Secondary steam is being dumped to atmosphere. There is no evidence of steam generator tube leakage, and containment parameters are as expected. There were no safety injections and none were required, and none of the primary power-operated relief valves lifted.
The licensee notified the NRC resident inspector.
****UPDATE 5/14/02 At 13:20 From B. Bates To R. Laura****
The initial report stated that the reactor coolant temperature is being maintained manually on the steam generator atmospheric relief valves at no-load Tave in accordance with plant procedures. Temperature control was actually established in automatic on the steam generator atmospheric relief valves and remains in automatic.
A statement was made in the original report that Unit 2 entered Technical Specification 3.0.3 for 34 minutes. Upon further review, there was no requirement to enter Technical Specification 3.0.3. The control system failures and plant system response caused the boration flowpaths from both the Refueling Water Storage Tank (RWST) and Boric Acid Storage Tanks to become inoperable. Therefore, the Unit was actually in Technical Specification 3.1.2.2 actions (a)and (b) concurrently. This did not constitute an entry into Technical Specification 3.0.3 because entry into both actions is not prohibited.
Another statement was made that both boration fiowpaths were subsequently returned to operable status by manual operator action. The boration flowpath from the boric acid storage tanks was returned to operable. However, after further investigation, it was determined that the boration flow path from the RWST remained inoperable due to the inability of the refueling water sequence to automatically initiate. The NRC Resident Inspector was notified.
Notified R3DO R. Gardner.