Event Notification Report for March 31, 2001
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
03/30/2001 - 03/31/2001
Power Reactor
Event Number: 37876
Facility: PALISADES
Region: 3 State: MI
Unit: [1] [] []
RX Type: [1] CE
NRC Notified By: R A VINCENT
HQ OPS Officer: JOHN MacKINNON
Region: 3 State: MI
Unit: [1] [] []
RX Type: [1] CE
NRC Notified By: R A VINCENT
HQ OPS Officer: JOHN MacKINNON
Notification Date: 03/31/2001
Notification Time: 08:43 [ET]
Event Date: 03/31/2001
Event Time: 01:45 [EST]
Last Update Date: 03/31/2001
Notification Time: 08:43 [ET]
Event Date: 03/31/2001
Event Time: 01:45 [EST]
Last Update Date: 03/31/2001
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(ii)(A) - DEGRADED CONDITION
10 CFR Section:
50.72(b)(3)(ii)(A) - DEGRADED CONDITION
Person (Organization):
BRUCE BURGESS (R3)
BRUCE BURGESS (R3)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | N | 0 | Hot Standby | 0 | Hot Standby |
BORIC ACID DEPOSIT DISCOVERED AROUND ONE CONTROL ROD DRIVE MECHANISM (CRDM) MECHANICAL SEAL HOUSING.
During an inspection of the reactor head area following shutdown for a refueling outage, a boric acid deposit and a small amount of water were found on one (of 45) CRDM mechanical seal housing. These deposits may potentially indicate reactor coolant system through-wall leakage. Further investigation will be performed following plant cooldown to determine whether deposits resulted from through-wall leakage or mechanical joint leakage, and appropriate corrective actions will be taken prior to startup from the refueling outage.
Boric acid was spread over a one square foot area and there is not any significant buildup of boric acid deposits.
The NRC Resident Inspector was notified of this event by the licensee.
During an inspection of the reactor head area following shutdown for a refueling outage, a boric acid deposit and a small amount of water were found on one (of 45) CRDM mechanical seal housing. These deposits may potentially indicate reactor coolant system through-wall leakage. Further investigation will be performed following plant cooldown to determine whether deposits resulted from through-wall leakage or mechanical joint leakage, and appropriate corrective actions will be taken prior to startup from the refueling outage.
Boric acid was spread over a one square foot area and there is not any significant buildup of boric acid deposits.
The NRC Resident Inspector was notified of this event by the licensee.
Power Reactor
Event Number: 37878
Facility: PALO VERDE
Region: 4 State: AZ
Unit: [1] [] []
RX Type: [1] CE,[2] CE,[3] CE
NRC Notified By: DAN MARKS
HQ OPS Officer: CHAUNCEY GOULD
Region: 4 State: AZ
Unit: [1] [] []
RX Type: [1] CE,[2] CE,[3] CE
NRC Notified By: DAN MARKS
HQ OPS Officer: CHAUNCEY GOULD
Notification Date: 03/31/2001
Notification Time: 17:05 [ET]
Event Date: 03/31/2001
Event Time: 10:58 [MST]
Last Update Date: 03/31/2001
Notification Time: 17:05 [ET]
Event Date: 03/31/2001
Event Time: 10:58 [MST]
Last Update Date: 03/31/2001
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(ii)(A) - DEGRADED CONDITION
10 CFR Section:
50.72(b)(3)(ii)(A) - DEGRADED CONDITION
Person (Organization):
DAVE LOVELESS (R4)
DAVE LOVELESS (R4)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | N | 0 | Hot Shutdown | 0 | Hot Shutdown |
DISCOVERY OF BORIC ACID RESIDUE BUILDUP ON RCS HOT LEG SPARE THERMOWELL
On March 31, 2001, at approximately 10:58 mountain standard time (MST) engineering personnel performing preplanned visual examinations of reactor coolant system (RCS) piping in accordance with procedure requirements discovered boric acid residue on RCS hot leg spare thermowell 1JRCETW0121HB. The visual observation was characterized as white streaks fanning out from the hot leg and continuing up the taper of the thermowell with some build-up on the top of the tapered portion. There were no signs of dripping, spraying, puddles of liquid, or liquid running down the nozzle or hot leg The residue appeared dry.
Technical Specifications (TS) Limiting Condition for Operation (LCO) 3.4.14 permits no reactor coolant system (RCS) pressure boundary leakage and therefore, the discovery of leakage (presumed boric acid residue) from the hot leg thermowell was a degradation of a principal safety barrier. Therefore, the ENS notification of this event is in accordance with 10CFR50.72(b)(3)(ii). The control room personnel entered LCO 3.4.14 Condition B and are continuing to place the plant in Mode 5.
The RCS was being cooled down in preparation for Unit 1's ninth refueling outage. At the time of discovery, the RCS was at approximately 300 degrees F and 725 psia.
An investigation of this event will be conducted in accordance with the licensee's corrective action program. The cracking of Alloy 600 components both at Palo Verde and industry-wide has been attributed to axially oriented, primary water stress corrosion cracking (PWSCC). PWSCC is not considered a significant threat to the structural integrity of the RCS boundary or the thermowell as this type of cracking typically results only in small leaks, The bases for this conclusion is that if PWSCC occurred at Palo Verde, the cracks would be predominately axial in orientation. As in this case, the cracks would result in visibly detectable leakage that would be apparent during visual examinations, performed as part of walkdown inspections, before significant damage to the reactor coolant boundary occurred.
Palo Verde has a program for replacing the Alloy 600 thermowells. This thermowell was scheduled for replacement during this refueling outage. The plans to replace the thermowell remain unchanged.
No ESF actuations occurred and none were required. There were no structures, systems, or components that were inoperable at the time of discovery that contributed to this condition. There were no failures that rendered a train of a safety system inoperable and no failures of components with multiple functions were involved. The event did not result in the release of radioactivity to the environment and did not adversely affect the safe operation of the plant or health and safety of the public.
The NRC Resident Inspector was notified.
On March 31, 2001, at approximately 10:58 mountain standard time (MST) engineering personnel performing preplanned visual examinations of reactor coolant system (RCS) piping in accordance with procedure requirements discovered boric acid residue on RCS hot leg spare thermowell 1JRCETW0121HB. The visual observation was characterized as white streaks fanning out from the hot leg and continuing up the taper of the thermowell with some build-up on the top of the tapered portion. There were no signs of dripping, spraying, puddles of liquid, or liquid running down the nozzle or hot leg The residue appeared dry.
Technical Specifications (TS) Limiting Condition for Operation (LCO) 3.4.14 permits no reactor coolant system (RCS) pressure boundary leakage and therefore, the discovery of leakage (presumed boric acid residue) from the hot leg thermowell was a degradation of a principal safety barrier. Therefore, the ENS notification of this event is in accordance with 10CFR50.72(b)(3)(ii). The control room personnel entered LCO 3.4.14 Condition B and are continuing to place the plant in Mode 5.
The RCS was being cooled down in preparation for Unit 1's ninth refueling outage. At the time of discovery, the RCS was at approximately 300 degrees F and 725 psia.
An investigation of this event will be conducted in accordance with the licensee's corrective action program. The cracking of Alloy 600 components both at Palo Verde and industry-wide has been attributed to axially oriented, primary water stress corrosion cracking (PWSCC). PWSCC is not considered a significant threat to the structural integrity of the RCS boundary or the thermowell as this type of cracking typically results only in small leaks, The bases for this conclusion is that if PWSCC occurred at Palo Verde, the cracks would be predominately axial in orientation. As in this case, the cracks would result in visibly detectable leakage that would be apparent during visual examinations, performed as part of walkdown inspections, before significant damage to the reactor coolant boundary occurred.
Palo Verde has a program for replacing the Alloy 600 thermowells. This thermowell was scheduled for replacement during this refueling outage. The plans to replace the thermowell remain unchanged.
No ESF actuations occurred and none were required. There were no structures, systems, or components that were inoperable at the time of discovery that contributed to this condition. There were no failures that rendered a train of a safety system inoperable and no failures of components with multiple functions were involved. The event did not result in the release of radioactivity to the environment and did not adversely affect the safe operation of the plant or health and safety of the public.
The NRC Resident Inspector was notified.