Event Notification Report for August 05, 2000
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
08/04/2000 - 08/05/2000
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
Power Reactor
Event Number: 37208
Facility: BRUNSWICK
Region: 2 State: NC
Unit: [] [2] []
RX Type: [1] GE-4,[2] GE-4
NRC Notified By: STUART BYRD
HQ OPS Officer: LEIGH TROCINE
Region: 2 State: NC
Unit: [] [2] []
RX Type: [1] GE-4,[2] GE-4
NRC Notified By: STUART BYRD
HQ OPS Officer: LEIGH TROCINE
Notification Date: 08/05/2000
Notification Time: 08:07 [ET]
Event Date: 08/05/2000
Event Time: 04:28 [EDT]
Last Update Date: 08/21/2000
Notification Time: 08:07 [ET]
Event Date: 08/05/2000
Event Time: 04:28 [EDT]
Last Update Date: 08/21/2000
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(iii)(D) - ACCIDENT MITIGATION
10 CFR Section:
50.72(b)(2)(iii)(D) - ACCIDENT MITIGATION
Person (Organization):
GEORGE BELISLE (R2)
GEORGE BELISLE (R2)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | N | Y | 100 | Power Operation | 100 | Power Operation |
DISCOVERY OF A MINIMAL AMOUNT OF WATER IN THE REACTOR CORE ISOLATION COOLING OIL SYSTEM
The following text is a portion of a facsimile received from the licensee:
"EVENT: The Unit 2 the Reactor Core Isolation Cooling (RCIC) system was discovered to have a minimal amount of water in the oil system. Following investigation of the event and replacement of the oil, the RCIC turbine was successfully manually started and operated normally. During a subsequent automatic start for post-maintenance test requirements, the turbine tripped on high exhaust pressure apparently caused by the governor system's slow response time. Investigation of the turbine control system is continuing."
"CORRECTIVE ACTION(S): Continue the investigation to determine the root cause of the water in the oil system and the response of the governor control system."
"INITIAL SAFETY SIGNIFICANCE EVALUATION: Minimal. The High Pressure Coolant Injection System, Automatic [Depressurization] System, Low Pressure Core Spray, and the Low Pressure Coolant Injection System were operable throughout the event."
The licensee stated that, as a result of this issue, the unit is currently in a 14-day limiting condition for operation in accordance with Technical Specification 3.5.2. The licensee also stated that all other systems functioned as required.
The licensee notified the NRC resident inspector.
* * * UPDATE ON 8/21/00 @ 1050 BY ELBERFELD TO GOULD * * * RETRACTION
Upon further investigation, it has been determined that the condition resulting in the RCIC turbine trip developed during the period of time that the system was inoperable for maintenance, and that there was no loss of safety function.
After the notification was made it was determined that the trip of the RCIC turbine was caused by the presence of air in the control system for the governor valve positioning servo. The presence of air delayed the closing of the governor valve during the RCIC turbine start sequence, allowing the turbine speed to increase, thus increasing turbine exhaust pressure above the trip setpoint. The presence of air was introduced by the maintenance activities associated with changing the turbine lube oil. An acknowledged industry expert was consulted and confirmed that one controlled manual start would not be considered adequate to remove air from the governor control system even with a substantial run duration. Experience has shown that multiple starts, at least 2 to 3 governor valve strokes, may be needed to remove the air that can cause abnormal turbine starts.
Review of the "as found" condition of the RCIC system and the RCIC system performance before and after the turbine trip indicates that the RCIC system would have successfully performed its intended functions prior to being taken out of service for maintenance on August 4, 2000. This is based on the following.
* The system quick started and ran successfully on August 2, 2000, prior to the oil sample being taken that contained the water.
* The presence of water in the lube oil did not cause the turbine trip and did not have an adverse impact on short-term system operability.
* Both turbine trips during the quick-starts were the result of minimal governor valve stroking after the lube oil changes introduced air into the governor valve control system.
* The RCIC turbine was able to achieve a quick-start without tripping, during the performance of OPT-10.1.1 on August 7, 2000, after the governor valve had been stroked twice (i.e., the controlled manual start and a failed quick-start).
This event is being retracted by the licensee.
The NRC Resident Inspector was notified by the licensee. The R2DO (Paul Fredrickson) was notified by the NRC Operations Officer.
The following text is a portion of a facsimile received from the licensee:
"EVENT: The Unit 2 the Reactor Core Isolation Cooling (RCIC) system was discovered to have a minimal amount of water in the oil system. Following investigation of the event and replacement of the oil, the RCIC turbine was successfully manually started and operated normally. During a subsequent automatic start for post-maintenance test requirements, the turbine tripped on high exhaust pressure apparently caused by the governor system's slow response time. Investigation of the turbine control system is continuing."
"CORRECTIVE ACTION(S): Continue the investigation to determine the root cause of the water in the oil system and the response of the governor control system."
"INITIAL SAFETY SIGNIFICANCE EVALUATION: Minimal. The High Pressure Coolant Injection System, Automatic [Depressurization] System, Low Pressure Core Spray, and the Low Pressure Coolant Injection System were operable throughout the event."
The licensee stated that, as a result of this issue, the unit is currently in a 14-day limiting condition for operation in accordance with Technical Specification 3.5.2. The licensee also stated that all other systems functioned as required.
The licensee notified the NRC resident inspector.
* * * UPDATE ON 8/21/00 @ 1050 BY ELBERFELD TO GOULD * * * RETRACTION
Upon further investigation, it has been determined that the condition resulting in the RCIC turbine trip developed during the period of time that the system was inoperable for maintenance, and that there was no loss of safety function.
After the notification was made it was determined that the trip of the RCIC turbine was caused by the presence of air in the control system for the governor valve positioning servo. The presence of air delayed the closing of the governor valve during the RCIC turbine start sequence, allowing the turbine speed to increase, thus increasing turbine exhaust pressure above the trip setpoint. The presence of air was introduced by the maintenance activities associated with changing the turbine lube oil. An acknowledged industry expert was consulted and confirmed that one controlled manual start would not be considered adequate to remove air from the governor control system even with a substantial run duration. Experience has shown that multiple starts, at least 2 to 3 governor valve strokes, may be needed to remove the air that can cause abnormal turbine starts.
Review of the "as found" condition of the RCIC system and the RCIC system performance before and after the turbine trip indicates that the RCIC system would have successfully performed its intended functions prior to being taken out of service for maintenance on August 4, 2000. This is based on the following.
* The system quick started and ran successfully on August 2, 2000, prior to the oil sample being taken that contained the water.
* The presence of water in the lube oil did not cause the turbine trip and did not have an adverse impact on short-term system operability.
* Both turbine trips during the quick-starts were the result of minimal governor valve stroking after the lube oil changes introduced air into the governor valve control system.
* The RCIC turbine was able to achieve a quick-start without tripping, during the performance of OPT-10.1.1 on August 7, 2000, after the governor valve had been stroked twice (i.e., the controlled manual start and a failed quick-start).
This event is being retracted by the licensee.
The NRC Resident Inspector was notified by the licensee. The R2DO (Paul Fredrickson) was notified by the NRC Operations Officer.
Power Reactor
Event Number: 37209
Facility: THREE MILE ISLAND
Region: 1 State: PA
Unit: [1] [] []
RX Type: [1] B&W-L-LP,[2] B&W-L-LP
NRC Notified By: J SCHORK
HQ OPS Officer: JOHN MacKINNON
Region: 1 State: PA
Unit: [1] [] []
RX Type: [1] B&W-L-LP,[2] B&W-L-LP
NRC Notified By: J SCHORK
HQ OPS Officer: JOHN MacKINNON
Notification Date: 08/05/2000
Notification Time: 21:45 [ET]
Event Date: 08/05/2000
Event Time: 20:54 [EDT]
Last Update Date: 08/05/2000
Notification Time: 21:45 [ET]
Event Date: 08/05/2000
Event Time: 20:54 [EDT]
Last Update Date: 08/05/2000
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(1)(ii)(B) - OUTSIDE DESIGN BASIS
10 CFR Section:
50.72(b)(1)(ii)(B) - OUTSIDE DESIGN BASIS
Person (Organization):
JACK MCFADDEN (R1)
JACK MCFADDEN (R1)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | Y | 100 | Power Operation | 100 | Power Operation |
DURING TESTING ONE CUBICLE OF THE CONTROL BUILDING ENVELOPE, THE 1D 4160 VOLT SWITCHGEAR ROOM WAS FOUND TO BE SLIGHTLY NEGATIVE IN PRESSURE.
"At 2054 hours on Saturday, August 5, 2000-AmerGen identified a condition that is outside the design basis at TMI Unit 1. Functional testing of the TMI-1 Control Building Envelope {CBE} was in process to verify that the design basis of the Control Building Emergency Ventilation System had been maintained following plant
modifications to improve the reliability of the system. Results of the Functional testing found that one cubicle of the Control Building Envelope, the 1D 4160 Volt Switchgear room, located on the 338' elevation of the Control Tower, 1 floor below the Control Room, was slightly negative in regards to internal atmospheric pressure as compared to outside air pressure. The TMI-1 UFSAR, Update 15 states in section 7.4.5.2.1 in part:
" ....A positive pressure of > or equal to 0.10 inches w.g. {water gauge} is not a criterion for the entire CBE. The pressure requirement in the cubicles of the CBE, other than the Main Control Room, is that they are maintained at a positive pressure with respect to the areas outside the CBE.
"The functional testing found that the ID 4160 Switchgear room was approximately 0.04 inches w.g. negative in regards to areas outside the CBE. Subsequent adjustments to the Control Building Emergency Ventilation System restored the area to a positive pressure in regards to areas outside the CBE. Additional evaluation and testing is in progress to determine the root cause of the event.
"The potential consequences of the condition found are believed to be minimal. No actual in-leakage pathway was identified and if the Control Building Emergency Ventilation System been called upon to operate in the re-circulation mode and had in-leakage occurred, the air in-leakage would have been filtered by the CBEVS
charcoal filters prior to supply to the Control Room. Thus, the dose consequences to the operators would have been very minimal due to the low amount of in-leakage and filtration prior to supply to the control room."
A follow up 30 day LER will be submitted.
The NRC Resident Inspector was notified of this event by the licensee.
"At 2054 hours on Saturday, August 5, 2000-AmerGen identified a condition that is outside the design basis at TMI Unit 1. Functional testing of the TMI-1 Control Building Envelope {CBE} was in process to verify that the design basis of the Control Building Emergency Ventilation System had been maintained following plant
modifications to improve the reliability of the system. Results of the Functional testing found that one cubicle of the Control Building Envelope, the 1D 4160 Volt Switchgear room, located on the 338' elevation of the Control Tower, 1 floor below the Control Room, was slightly negative in regards to internal atmospheric pressure as compared to outside air pressure. The TMI-1 UFSAR, Update 15 states in section 7.4.5.2.1 in part:
" ....A positive pressure of > or equal to 0.10 inches w.g. {water gauge} is not a criterion for the entire CBE. The pressure requirement in the cubicles of the CBE, other than the Main Control Room, is that they are maintained at a positive pressure with respect to the areas outside the CBE.
"The functional testing found that the ID 4160 Switchgear room was approximately 0.04 inches w.g. negative in regards to areas outside the CBE. Subsequent adjustments to the Control Building Emergency Ventilation System restored the area to a positive pressure in regards to areas outside the CBE. Additional evaluation and testing is in progress to determine the root cause of the event.
"The potential consequences of the condition found are believed to be minimal. No actual in-leakage pathway was identified and if the Control Building Emergency Ventilation System been called upon to operate in the re-circulation mode and had in-leakage occurred, the air in-leakage would have been filtered by the CBEVS
charcoal filters prior to supply to the Control Room. Thus, the dose consequences to the operators would have been very minimal due to the low amount of in-leakage and filtration prior to supply to the control room."
A follow up 30 day LER will be submitted.
The NRC Resident Inspector was notified of this event by the licensee.