Event Notification Report for October 02, 1999
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
10/01/1999 - 10/02/1999
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
Power Reactor
Event Number: 36255
Facility: SOUTH TEXAS
Region: 4 State: TX
Unit: [] [2] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: FRAWLEY
HQ OPS Officer: CHAUNCEY GOULD
Region: 4 State: TX
Unit: [] [2] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: FRAWLEY
HQ OPS Officer: CHAUNCEY GOULD
Notification Date: 10/02/1999
Notification Time: 21:03 [ET]
Event Date: 10/02/1999
Event Time: 19:05 [CDT]
Last Update Date: 10/21/1999
Notification Time: 21:03 [ET]
Event Date: 10/02/1999
Event Time: 19:05 [CDT]
Last Update Date: 10/21/1999
Emergency Class: NON EMERGENCY
10 CFR Section:
73.71(b)(1) - SAFEGUARDS REPORTS
10 CFR Section:
73.71(b)(1) - SAFEGUARDS REPORTS
Person (Organization):
JEFF SHACKELFORD (R4)
JEFF SHACKELFORD (R4)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | N | Y | 94 | Power Operation | 94 | Power Operation |
UNACCOUNTED FOR ACCESS KEY. COMPENSATORY MEASURES WERE PUT INTO PLACE.
SEE HOO LOG FOR DETAILS.
THE RESIDENT INSPECTOR WAS NOTIFIED.
* * * UPDATE AT 1658 ON 10/21/99 BY KATHLEEN WORK TO JOLLIFFE * * *
THE LICENSEE DESIRES TO RETRACT THIS EVENT AS A REPORTABLE EVENT AND WILL LOG THIS EVENT IN THEIR SAFEGUARDS EVENT LOG SINCE SECURITY IMPLEMENTING COMPENSATORY ACTIONS WERE IMPLEMENTED WITHIN 15 MINUTES FROM THE TIME THE LICENSEE DISCOVERED THAT THE KEY WAS MISSING.
SEE THE HOO LOG FOR DETAILS.
THE LICENSEE INFORMED THE NRC RESIDENT INSPECTOR.
THE NRC OPERATIONS OFFICER NOTIFIED THE R4DO LINDA SMITH.
SEE HOO LOG FOR DETAILS.
THE RESIDENT INSPECTOR WAS NOTIFIED.
* * * UPDATE AT 1658 ON 10/21/99 BY KATHLEEN WORK TO JOLLIFFE * * *
THE LICENSEE DESIRES TO RETRACT THIS EVENT AS A REPORTABLE EVENT AND WILL LOG THIS EVENT IN THEIR SAFEGUARDS EVENT LOG SINCE SECURITY IMPLEMENTING COMPENSATORY ACTIONS WERE IMPLEMENTED WITHIN 15 MINUTES FROM THE TIME THE LICENSEE DISCOVERED THAT THE KEY WAS MISSING.
SEE THE HOO LOG FOR DETAILS.
THE LICENSEE INFORMED THE NRC RESIDENT INSPECTOR.
THE NRC OPERATIONS OFFICER NOTIFIED THE R4DO LINDA SMITH.
Power Reactor
Event Number: 36256
Facility: PALO VERDE
Region: 4 State: AZ
Unit: [1] [] []
RX Type: [1] CE,[2] CE,[3] CE
NRC Notified By: MARKS
HQ OPS Officer: CHAUNCEY GOULD
Region: 4 State: AZ
Unit: [1] [] []
RX Type: [1] CE,[2] CE,[3] CE
NRC Notified By: MARKS
HQ OPS Officer: CHAUNCEY GOULD
Notification Date: 10/03/1999
Notification Time: 18:04 [ET]
Event Date: 10/02/1999
Event Time: 09:53 [MST]
Last Update Date: 10/03/1999
Notification Time: 18:04 [ET]
Event Date: 10/02/1999
Event Time: 09:53 [MST]
Last Update Date: 10/03/1999
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(i) - DEG/UNANALYZED COND
10 CFR Section:
50.72(b)(2)(i) - DEG/UNANALYZED COND
Person (Organization):
JEFF SHACKELFORD (R4)
JEFF SHACKELFORD (R4)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | N | 0 | Hot Standby | 0 | Cold Shutdown |
REACTOR COOLANT SYSTEM PRESSURE BOUNDARY LEAKAGE
On October 2,1999 at approximately 0953 MST, Palo Verde Nuclear Generating Station (PVNGS) Unit 1 discovered evidence of reactor coolant system (RCS) pressure boundary leakage. PVNGS Unit 1 was shutdown in Mode 3 in its eighth refueling outage at the time of discovery and is now in Mode 5(as of 2035 on 10/2/99). Current RCS temperature is approximately 102 degrees Fahrenheit and RCS pressure is approximately 31 psia.
The leakage was discovered at two Inconel alloy 600 nozzles, one in each of the RCS hot legs. One was at the nozzle upstream of valve RCV-285 in the line to a steam generator #2 differential pressure instrument. The other was at the nozzle upstream of valve RCV-277 in the line to a steam generator #1 differential pressure instrument. The leakage was identified in the form of small deposits of boron accumulation around the circumference of the nozzles. PVNGS has conducted inspections of these nozzles during each refueling outage since the discovery that Inconel alloy 600 nozzles are susceptible to axial cracking when sensitized. No evidence of leakage was detected when inspected during the last outage, approximately 18 months ago. Isotopic analysis of the boron accumulation detected only long-lived radionuclides, indicating that it has taken over 3 years for the reactor coolant to migrate through the nozzle weld and wall thickness.
PVNGS Unit 1 Technical Specification Limiting Condition for Operation 3.4.14 (RCS Operational Leakage) permits no reactor coolant system pressure boundary leakage, therefore the evidence of leakage represents serious degradation of a principal safety barrier. Operators conservatively entered LCO 3.4.14 at 0953 MST on October 2, 1999. The difference in this ENS report time was due to the disparity between the isotopic analysis indicating at least 3 years age and the inspection conducted 18 months ago, causing suspicion that the boron deposits may have come from a different leak point.
PVNGS is replacing the two nozzles during the outage and will continue to inspect remaining Inconel alloy 600 nozzles. No ESF actuations occurred and none were required. No structures, systems or components were inoperable that contributed to this event, particularly the fuel cladding and the containment fission product barriers. PVNGS is not in an applicable mode requiring RCS integrity. 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 the health and safety of the public.
The Resident Inspector was notified.
On October 2,1999 at approximately 0953 MST, Palo Verde Nuclear Generating Station (PVNGS) Unit 1 discovered evidence of reactor coolant system (RCS) pressure boundary leakage. PVNGS Unit 1 was shutdown in Mode 3 in its eighth refueling outage at the time of discovery and is now in Mode 5(as of 2035 on 10/2/99). Current RCS temperature is approximately 102 degrees Fahrenheit and RCS pressure is approximately 31 psia.
The leakage was discovered at two Inconel alloy 600 nozzles, one in each of the RCS hot legs. One was at the nozzle upstream of valve RCV-285 in the line to a steam generator #2 differential pressure instrument. The other was at the nozzle upstream of valve RCV-277 in the line to a steam generator #1 differential pressure instrument. The leakage was identified in the form of small deposits of boron accumulation around the circumference of the nozzles. PVNGS has conducted inspections of these nozzles during each refueling outage since the discovery that Inconel alloy 600 nozzles are susceptible to axial cracking when sensitized. No evidence of leakage was detected when inspected during the last outage, approximately 18 months ago. Isotopic analysis of the boron accumulation detected only long-lived radionuclides, indicating that it has taken over 3 years for the reactor coolant to migrate through the nozzle weld and wall thickness.
PVNGS Unit 1 Technical Specification Limiting Condition for Operation 3.4.14 (RCS Operational Leakage) permits no reactor coolant system pressure boundary leakage, therefore the evidence of leakage represents serious degradation of a principal safety barrier. Operators conservatively entered LCO 3.4.14 at 0953 MST on October 2, 1999. The difference in this ENS report time was due to the disparity between the isotopic analysis indicating at least 3 years age and the inspection conducted 18 months ago, causing suspicion that the boron deposits may have come from a different leak point.
PVNGS is replacing the two nozzles during the outage and will continue to inspect remaining Inconel alloy 600 nozzles. No ESF actuations occurred and none were required. No structures, systems or components were inoperable that contributed to this event, particularly the fuel cladding and the containment fission product barriers. PVNGS is not in an applicable mode requiring RCS integrity. 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 the health and safety of the public.
The Resident Inspector was notified.