ENS 49014
ENS Event | |
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10:09 May 9, 2013 | |
Title | |
Event Description | During Callaway refueling outage 19 on 5/8/13 at approximately 1900 hour0.022 days <br />0.528 hours <br />0.00314 weeks <br />7.2295e-4 months <br /> CDT, water was observed dripping from piping insulation in the overhead by RCS loop 4. Further investigation determined it was near Safety Injection (EP) vent valve EPV0109. A scaffold was built and insulation was removed to perform an inspection. At approximately 0509 hours0.00589 days <br />0.141 hours <br />8.416005e-4 weeks <br />1.936745e-4 months <br /> CDT on 5/9/13, engineering inspected the piping and determined there was a crack in the socket weld where 3/4 inch vent valve EPV0109 is connected to the 'B' train injection piping to RCS loop 4 Cold Leg. The estimated leakage rate through the crack is 6 (six) drops per minute. The configuration of this vent valve is a 3/8 inch flow restrictor socket welded to the six inch piping and a 3/4 inch vent valve socket welded to the flow restrictor. The crack is in the socket weld between the ASME code class 1 flow restrictor socket and the ASME code class 2 vent piping.
Callaway plant was in mode 6 with refueling pool level greater than 23 feet above the reactor vessel flange at the time of the discovery. The 'A' RHR train which discharges to RCS loops 1 and 3 Cold Legs is the currently operable RHR train. 'B' RHR train was declared inoperable when the weld crack was identified. Only one RHR train is required to be operable at the present plant Mode of applicability. Repair plans are being developed. Basis for Reportability: This condition constitutes abnormal degradation of a principle safety barrier due to unacceptable welding defects within the primary coolant system. There is a check valve between this leak and the reactor coolant system. Therefore, this is considered unisolable and pressure boundary leakage. The licensee notified the NRC Resident Inspector. |
Where | |
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Callaway Missouri (NRC Region 4) | |
Reporting | |
10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | |
LER: | 05000483/LER-2013-006 |
Time - Person (Reporting Time:+-2.85 h-0.119 days <br />-0.017 weeks <br />-0.0039 months <br />) | |
Opened: | Gerry Rauch 07:18 May 9, 2013 |
NRC Officer: | Mark Abramovitz |
Last Updated: | May 9, 2013 |
49014 - NRC Website
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WEEKMONTHYEARENS 490142013-05-09T10:09:0009 May 2013 10:09:00
[Table view]10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Reactor Coolant Pressure Boundary Leakage 2013-05-09T10:09:00 | |