ENS 52271
ENS Event | |
|---|---|
02:00 Sep 30, 2016 | |
| Title | Unisolable Leak on Decay Heat Removal Piping Due to Weld Failure on a 1" Common Pipe |
| Event Description | At 2100 CDT on 09/29/16, while in Mode 6, both trains of Decay Heat (Residual Heat Removal) were declared inoperable due to a cracked weld on a 1" common pipe. The leak developed in a USAS B31.7, Class1 pipe at a weld upstream of pressure indication isolation valve DH-1037. The leak is not isolable from the common 8-inch Decay Heat piping and encompasses approximately 1/3 [one third] of the pipe circumference.
At the time of discovery, the unit was in Lowered Inventory with both Loops of Decay Heat in service. Subsequently, one train of Decay Heat has been secured to reduce the likelihood of crack propagation. One Train of Decay Heat remains in service providing the function of removing Decay Heat and the other train is readily available. The leakage impacts redundant equipment required to fulfill a safety function. In the current condition, both trains are required to be operable to meet Technical Specification LCO 3.9.5, Decay Heat Removal (DHR) and Coolant Circulation-Low water Level. This condition is reportable per 10 CFR 50.72(b)(3)(v)(B) for any event or condition that results in a loss of Safety Function associated with the Decay Heat System (Residual Heat Removal System). The licensee has notified the NRC Resident Inspector. The leak is approximately 0.25 gallons per minute and pipe pressure is 140 psi. Compensatory measures are in place and include an individual posted to watch the pipe in case plugging is necessary. Repairs to the pipe will be completed once pipe is able to be drained. |
| Where | |
|---|---|
Arkansas Nuclear  Arkansas (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | |
| LER: | 05000313/LER-2016-004 |
| Time - Person (Reporting Time:+2.02 h0.0842 days <br />0.012 weeks <br />0.00277 months <br />) | |
| Opened: | Mark Gohman 04:01 Sep 30, 2016 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Sep 30, 2016 |
| 52271 - NRC Website
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