ENS 49353
ENS Event | |
|---|---|
10:10 Sep 18, 2013 | |
| Title | Boroscopic Inspection of Reactor Vessel Head Determined Evidence of Boundary Leakage |
| Event Description | Boroscopic inspection of the reactor head assembly during refuel outage A1R17 has determined that white powder residue observed at reactor head penetrations 41, 49, 61, 65, and 73 is evidence of past Reactor Coolant System pressure boundary leakage at one or more of these locations. This determination was made today at 0510 [CDT] after completion of boroscopic inspections and consultation with the reactor head vendor. These reactor head penetrations are control rod drive mechanism (CRDM) penetrations. The location of the identified leakage is suspected to be the omega seal welded threaded connection on one or more of these CRDM penetrations. Further inspections must be performed to confirm the exact leakage location. This condition will be repaired before U-1 returns to mode 4.
The licensee has notified the NRC Resident Inspector.
The purpose of this report is to retract ENS report #49353 (September 18, 2013). This report was made after boroscopic inspection of the Unit 1 reactor head assembly during refueling outage A1R17 determined that white powder residue observed at five Reactor Pressure Vessel (RPV) head penetrations was evidence of past Reactor Coolant System (RCS) pressure boundary leakage at one or more of these locations. At 1400 CDT on Wednesday, September 25, 2013, the Braidwood Nuclear Power Station (BNPS) concluded that the prior ENS notification could be retracted because the Plant Operations Review Committee had concluded that the white powder residue observed at five Unit 1 RPV head penetrations was not evidence of past RCS pressure boundary leakage. A detailed examination plan was implemented, which included a disassembly of the Digital Rod Position Indication (DRPI) and Control Rod Drive Mechanism (CRDM) coils for all five penetrations and a detailed visual examination using remote video equipments. The visual examinations used remote video equipments to inspect the lower and intermediate canopy seal weld areas for the five CRDMs. In addition, an examination of the upper canopy seal weld areas and a bare-metal inspection of the Reactor Pressure Vessel Head did not identify any evidence of boric acid leakage. Based on these inspections and a review of available photos from previous outages, BNPS concluded that the white residues were from incomplete cleaning in prior outages. The licensee has notified the NRC Resident Inspector. Notified R3DO (Dickson). |
| Where | |
|---|---|
Braidwood  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | |
| Time - Person (Reporting Time:+1.08 h0.045 days <br />0.00643 weeks <br />0.00148 months <br />) | |
| Opened: | Johnathan Zarndt 11:15 Sep 18, 2013 |
| NRC Officer: | John Shoemaker |
| Last Updated: | Sep 27, 2013 |
| 49353 - NRC Website
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WEEKMONTHYEARENS 561532022-10-07T06:19:0007 October 2022 06:19:00
[Table view]10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Control Rod Drive Mechanism (CRDM) Penetration Degraded ENS 536522018-10-08T05:00:0008 October 2018 05:00:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Reactor Coolant System Pressure Boundary Leakage ENS 533542018-04-20T22:30:00020 April 2018 22:30:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Degraded Reactor Vessel Head ENS 522752016-10-02T21:00:0002 October 2016 21:00:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Liquid Penetration Examination Results in Indications on Reactor Vessel Head Penetration ENS 509532015-04-03T21:31:0003 April 2015 21:31:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Liquid Penetration Examination Results in Indication on Reactor Vessel Head Penetration ENS 493532013-09-18T10:10:00018 September 2013 10:10:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Boroscopic Inspection of Reactor Vessel Head Determined Evidence of Boundary Leakage ENS 493432013-09-14T07:00:00014 September 2013 07:00:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Liquid Penetration Examination Results in Indication on Reactor Vessel Head Penetration ENS 479342012-04-23T06:00:00023 April 2012 06:00:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Ultrasonic Examination Results in an Indication on the Reactor Pressure Vessel Head Penetration 2022-10-07T06:19:00 | |