ENS 49288
ENS Event | |
|---|---|
00:16 Jun 10, 2013 | |
| Title | Part 21 - Auxiliary Feedwater Level Control Valve Stem/Plug Assembly Out of Tolerance |
| Event Description | On June 9, 2013, Auxiliary Feedwater Level Control Valve [AFW LCV] 1-LCV-3-156-A, failed its closed-to-open stroke time during quarterly surveillance testing. This level control valve is a basic component which regulates auxiliary feedwater (AFW) flow to Steam Generator 2. The valve failed to open during two attempts. Local observation during testing indicated that the valve 'popped' off the seat, and then traveled smoothly to its full open position on the third and fourth attempt. The failure was determined to be a Maintenance Rule Functional Failure and a CC1 Functional Failure. There were no previous indication(s) of this failure mode during the previous quarterly stroke time testing. The valve internals were replaced on October 7, 2009, during a refueling outage.
TVA installed a new trim kit which included the cage, lower seat ring, and stem/plug assembly. The valve was returned to service on June 12, 2013, following successful post modification testing. A Kepner-Tregoe (K-T) problem analysis revealed the direct cause was binding due to the stem/plug assembly being out of tolerance. Upon inspection, the Total Indicated Run-out (TIR) of the stem/plug assembly removed from the affected valve was determined to be 0.022 inches. The valve was manufactured by Dresser Masoneilan with a TIR specification of less than or equal to 0.005 inches. The valve model and stem/plug assembly part numbers are: Valve: Masoneilan Model 37-20721, 4 inch Control Valve Stem: 012160204-215-J000 Plug: 011501710-1H6U Inspection of the five unused spare stem/plug assemblies in storage had a TIR that ranged from 0.006 to 0.022 inches, which is outside vendor specifications. Because the stem/plug assembly removed from the affected AFW LCV and five of the unused stem/plug assemblies were found to be out-of-tolerance, a condition exists and is being reported in accordance with 10CFR50 Part 21.21(d). Similar LCVs in the AFW systems were tested and are OPERABLE with no known defects. A detailed report using NRC Form 366, Licensee Event Report, will be submitted to the NRC by 09/15/13 in accordance with 10CFR50 Part 21.21(d)(3)(ii). The licensee has notified the NRC Resident Inspector. |
| Where | |
|---|---|
Watts Bar  Tennessee (NRC Region 2) | |
| Reporting | |
| 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | |
| Time - Person (Reporting Time:+1621.57 h67.565 days <br />9.652 weeks <br />2.221 months <br />) | |
| Opened: | Russell A. Stroud 13:50 Aug 16, 2013 |
| NRC Officer: | Dong Park |
| Last Updated: | Aug 16, 2013 |
| 49288 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 492882013-06-10T00:16:00010 June 2013 00:16:00
[Table view]10 CFR 21.21(d)(3)(i), Failure to Comply or Defect Part 21 - Auxiliary Feedwater Level Control Valve Stem/Plug Assembly Out of Tolerance 2013-06-10T00:16:00 | |