ENS 41128
ENS Event | |
|---|---|
21:30 Oct 16, 2004 | |
| Title | Reactor Vessel Head Nozzle Cracking |
| Event Description | On 10/16/04, with the Plant in Mode 6, Nuclear Management Company identified through wall cracks in the inconel buttering adjacent to the J-weld on reactor head penetrations 29 and 30. Ultrasonic examinations of the reactor vessel head were being performed in accordance with the First Revised Order, EA-03-009. The ultrasonic examinations identified leak path detection indications. Therefore, in accordance with the Order, a bare metal visual inspection of the exterior of the reactor head was performed. No evidence of leakage was discovered. A dye-penetrant examination was then performed. The dye-penetrant exam showed minor surface indications that required further examination. Following minor excavation of the weld surface, the through wall cracks were identified.
This condition was determined to be reportable at 1730 EST for penetration 30, and at 1915 EST for penetration 29. This notification is being made in accordance with 10 CFR 50.72(b)(3)(ii)(A). Reactor head penetrations 29 and 30 will be repaired prior to placing the reactor vessel head back in service. The licensee notified the NRC Resident Inspector.
On October 17, 2004, Nuclear Management Company notified the NRC, via non-emergency event report 41128 that leak path detection indications had been identified in two reactor pressure vessel head control rod drive mechanism nozzle penetrations at Palisades. At that time, the probable cause of the identified indications was believed to be primary water stress corrosion cracking (PWSCC). As a result, event report 41128 was made in accordance with 10 CFR 50.72(b)(3)(ii)(A) as a condition that resulted in a principle safety barrier being seriously degraded. Based on a recently completed engineering evaluation that compared the indications found in 2004 to the indications identified in subsequent examinations, it was determined the indications originally discovered in 2004 were embedded welding indications, caused by the original welding process. Since the indications identified in 2004 were not caused by PWSCC, serious degradation of a principle safety barrier did not exist. Consequently, the reporting criterion of 10 CFR 50.72(b)(3)(ii)(A) is not applicable. Therefore, event report 41128 is being retracted. In addition, Palisades Licensee Event Report (LER), 2004-002, 'Leak Path Indications Identified in Reactor Pressure Vessel Head Nozzle Penetrations,' is being cancelled. The licensee has notified the NRC Resident Inspector. Notified R3DO (Peterson). |
| Where | |
|---|---|
Palisades  Michigan (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | |
| Time - Person (Reporting Time:+3.55 h0.148 days <br />0.0211 weeks <br />0.00486 months <br />) | |
| Opened: | Amy Hazelhoff 01:03 Oct 17, 2004 |
| NRC Officer: | Bill Gott |
| Last Updated: | Nov 19, 2014 |
| 41128 - NRC Website | |
WEEKMONTHYEARENS 548972020-09-11T23:30:00011 September 2020 23:30:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | Degraded Condition ENS 537492018-11-21T05:00:00021 November 2018 05:00:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Degraded Condition Identified During Surface Inspection of Reactor Head Nozzle Penetration ENS 537342018-11-11T04:00:00011 November 2018 04:00:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Degraded Condition Due to Indication During Ultrasonic Inspection of Reactor Head Nozzle Penetration ENS 537332018-11-10T05:00:00010 November 2018 05:00:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Boric Acid Identified on Reactor Vessel Head Penetration ENS 527222017-05-02T13:28:0002 May 2017 13:28:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Failed Ultrasonic Testing of Weld ENS 497962014-02-05T18:00:0005 February 2014 18:00:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Degraded Condition Discovered on Pressurizer Nozzle Weld During Testing ENS 497732014-01-29T14:00:00029 January 2014 14:00:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Indications Identified on Control Rod Drive Mechanism Housings ENS 481822012-08-12T08:18:00012 August 2012 08:18:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Degraded Condition Reported Based on the Discovery of Pressure Boundary Leakage ENS 411282004-10-16T21:30:00016 October 2004 21:30:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Reactor Vessel Head Nozzle Cracking 2020-09-11T23:30:00 [Table view] | |