05000255/LER-2020-002, Indications Identified in Reactor Pressure Vessel Head Nozzle Penetrations
| ML20314A143 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 11/05/2020 |
| From: | Hardy J Entergy Nuclear Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| PNP 2020-036 LER 2020-002-00 | |
| Download: ML20314A143 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded |
| 2552020002R00 - NRC Website | |
text
Entergy Nuclear Operations, Inc.
Palisades Nuclear Plant 27780 Blue Star Memorial Highway Covert, MI 49043 Tel 269 764 2000 Jeffery A. Hardy Regulatory Assurance Manager PNP 2020-036 November 5, 2020 10 CFR 50.73 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
SUBJECT:
LER 2020-002 Indications Identified in Reactor Pressure Vessel Head Nozzle Penetrations Palisades Nuclear Plant Docket 50-255 Renewed Facility Operating License No. DPR-20 Entergy Nuclear Operations, Inc., submits the enclosed Licensee Event Report (LER), 2020-002-00, for the Palisades Nuclear Plant. The event is reportable in accordance with 10 CFR 50.73(a)(2)(ii)(A) as a degraded condition. The LER describes a condition in which indications were identified in reactor vessel head penetrations by inspections performed during a refueling outage.
This letter contains no new commitments and no revisions to existing commitments.
Should you have any questions concerning this report, please contact Mr. Jeffery Hardy, Regulatory Assurance Manager, at (269) 764-2011.
Respectfully, JAH/bed Attachment: LER 2020-002-00, Indications Identified in Reactor Pressure Vessel Head Nozzle Penetrations cc:
NRC Region III Regional Administrator NRC Senior Resident Inspector - Palisades NRC Project Manager - Palisades
Attachment LER 2020-002-00 Indications Identified in Reactor Pressure Vessel Head Nozzle Penetrations 2 Pages Follow
Abstract
At the Palisades Nuclear Plant, on September 11, 2020, with the plant in Mode 6, at 0% power, during in-service inspection of reactor pressure vessel head (RPVH) penetrations, ultrasonic testing (UT) data analysis revealed relevant indications in RPVH penetration nozzle 34. On September 13, 2020, relevant indications were also identified in RPVH penetration nozzle 17. UT analysis determined that the indications were consistent with primary water stress corrosion cracking (PWSCC). There was no leak path signal detected.
The plant was in cold shutdown for a refueling outage at the time of discovery. Nozzles 17 and 34 were repaired and the RPVH was returned to service. The safety significance of this event was minimal. This event is reportable in accordance with 10 CFR 50.73(a)(2)(ii)(A) as a condition that resulted in a principle safety barrier being seriously degraded.
NRC FORM 366 (08-2020)
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LICENSEE EVENT REPORT (LER)
(See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
- 1. FACILITY NAME PALISADES
- 2. DOCKET NUMBER 05000255
- 3. LER NUMBER Palisades Nuclear Plant 05000-255 2020
- - 002
- - 00
NARRATIVE
EVENT DESCRIPTION
On September 11, 2020, with the plant in Mode 6, at 0% power, during in-service inspection of reactor pressure vessel [RPV;AB] head (RPVH) penetrations, ultrasonic testing (UT) data analysis revealed relevant indications in RPVH penetration nozzle [NZL;AB] 34. On September 13, 2020, relevant indications were also identified in RPVH penetration nozzle 17. UT analysis determined that the indications were consistent with primary water stress corrosion cracking (PWSCC). There was no leak path signal detected.
CAUSE OF THE EVENT
The Palisades RPVH penetrations are constructed of Inconel Alloy 600 material which is susceptible to PWSCC.
This resulted in unacceptable flaws being identified in RPVH penetrations 17 and 34.
ASSESSMENT OF SAFETY CONSEQUENCES
The safety significance of the flaws presence during operation was minimal. The Palisades RPVH inspection program is in accordance with the requirements of ASME Code Case 729-4, as modified by the additional limitations set forth in 10 CFR 50.55a(g)(6)(ii)(D). This provides assurance against any credible PWSCC degradation event that would challenge nuclear safety. There were no consequences to the general safety of the public, nuclear safety, industrial safety, or radiological safety for this event.
CORRECTIVE ACTIONS
Framatome executed half-nozzle replacements using the inside diameter temper bead welding process to repair the flawed reactor head nozzles, and the RPVH was returned to service.
PREVIOUS SIMILAR EVENTS
LER 2018-003 - Indications Identified in Reactor Pressure Vessel Head Nozzle Penetrations, Palisades Nuclear Plant, dated January 3, 2019.
LER 2004-002 - Leak Path Indications Identified in Reactor Pressure Vessel Head Nozzle Penetrations, Palisades Nuclear Plant, dated December 9, 2004.