ENS 52224
ENS Event | |
|---|---|
17:47 Sep 6, 2016 | |
| Title | |
| Event Description | At 1347 EDT on September 6, 2016, the non-essential service water header was declared inoperable due to what appeared to be a leak on a filet weld on a slip-on flange upstream of the 23 service water pump discharge valve SWN-2-2. [Operators] entered LCO 3.0.3 based on Engineering input with no code case to support an immediate determination of operability. The 23 service water pump was secured and the discharge valve SWN-2-2 was closed isolating the leak and restoring the non-essential SW header to operable status. With the discharge valve closed, LCO 3.0.3 was exited at 1417 EDT on September 6, 2016. The declaration of the inoperability of the non-essential service water header is considered a loss of safety function for purposes of reporting under 10 CFR 50.72(b)(3)(v). Further investigation of the leak revealed [that the leak had occurred at] a pipe flaw rather than at the weld location. An operability evaluation is ongoing. There was no reduction in power while in LCO 3.0.3 and no other issues arose.
The licensee notified the NRC Resident Inspector.
Indian Point Unit 2 is retracting the 8-hour non-emergency notification made on September 7, 2016, at 1647 hours0.0191 days <br />0.458 hours <br />0.00272 weeks <br />6.266835e-4 months <br /> EDT (EN#52224). The notification on September 7, 2016, reported a safety system functional failure (SSFF) as a result of declaring the non-essential service water (SW) header inoperable due to discovery of a through wall leak on the discharge line from the 23 SW Pump. The leak appeared to be on the downstream fillet weld on the north side of the pipe spool piece. At the time the exact location of the leak could not be established due to the geometry of the area and its carbon fiber coating. Because there is no qualified NDE inspection technique for fillet welds and the analytical methods provided in ASME code Case N-513-3 are not applicable to fillet welds, operability of the effected section of the SW System could not be demonstrated and the SW piping was conservatively considered inoperable. Further investigation of the leak determined the leak occurred mid-pipe 1/2 inch upstream from a slip-on flange socket weld and not on the weld itself. The weld location is ASME Section XI Class 3, nuclear safety-related, Seismic Class 1. An engineering evaluation was performed of the pipe defect and concluded the identified through-wall defect on the pipe spool piece did not result in any structural, flooding, spraying condition or SW system capacity issues which would adversely impact any normal or accident design functions of the SW system or any other nuclear safety-related equipment or component to perform their design safety functions from the time of the leak occurrence to the isolation of the pipe. The structural portion of the evaluation was performed using the ASME CC N-513-3 methodology but the code case was not invoked because the flaw was isolated and a code repair was made. The 23 SW Pump discharge line spool piece is a 14 inch NPS schedule STD cement-lined carbon steel pipe having a nominal wall thickness of 0.375 inches with slip-on flanges welded on both sides with fillet welds on the exterior. The function of this spool piece is to connect the 23 Zurn Strainer outlet to the isolation valve SWN-2-2. The degradation mechanism was likely due to corrosion of the carbon steel on the underside of the cement lining due to a lining defect. The licensee will notify the NRC Resident Inspector. Notified R2DO (Krohn). |
| Where | |
|---|---|
Indian Point  New York (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+23 h0.958 days <br />0.137 weeks <br />0.0315 months <br />) | |
| Opened: | Erik Silko 16:47 Sep 7, 2016 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Sep 23, 2016 |
| 52224 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |