05000255/LER-2007-002, Re Inoperable Containment Due to Containment Air Cooler Through-Wall Flaw
| ML070871046 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 03/19/2007 |
| From: | Harden P Nuclear Management Co |
| To: | Document Control Desk, NRC/NRR/ADRO |
| References | |
| LER 07-002-00 | |
| Download: ML070871046 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 2552007002R00 - NRC Website | |
text
March 1 2007 U. S. Nuclear Regulatory Commission Document Control Washington, 20555-0001 Palisades Nuclear Plant Docket 50-255 License DPR-20 Palisades Nuclear Plant Operated by Nuclear Management Company, LLC 10 CFR 50.73(a)(2)(v)(C)
Licensee Event Report 07-002, Inoperable Containment Due to Containment Air Cooler Through-Wall Flaw Licensee Report (LER)07-002 is enclosed. The describes the discovery of a through-wall a containment air cooler tube and resultant effect on the containment boundary.
event is reportable accordance with 10 CFR 50.73(a)(2)(v)(C).
Summary of Commitments This letter contains no new commitments and no revisions to existing commitments.
Paul Harden Site Vice President, Palisades Nuclear Plant Nuclear Management Company, Enclosure (1)
CC Administrator, Region III, USNRC Project Manager, Palisades, USNRC Resident Inspector, Palisades, USNRC 27780 Blue Star Memorial Highway
- Covert, Michigan 49043-9530 Telephone: 269.764.2000
ENCLOSURE 1 LER 07-002, inoperable Containment Due to Containment Air Cooler Through-Wall Flaw 3 Pages Follow
LICEWEE EVENT REPORT QLER)
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inoperable Containment Due to Containment Air Cooler Through-Wall Flaw REPORTABLE SUBMISSION On January 19, 2007, with the plant in Model, a small service water leak (approximately 60 drops per minute) was identified in VHX-4 containment air cooler (CAC). The leak was subsequently determined to be from a pin-hole in a single cooling coil tube at the H-bend fitting.
The CAC cooling coil is a part of the containment boundary, and is required to be structurally sound to ensure that post accident containment leakage will not exceed allowable leakage (La). Therefore, Technical Specification Limiting Condition For Operation 3.6.1, "Containment," is initially applicable for any through-wall defect noted in a CAC cooling coil.
Although the size of the identified pin-hole would not have challenged La, it was not possible to characterize the flaw to verify the operability of the cooling coil for post-accident conditions over the CAC's mission time.
(his event is reportable in accordance with 10 CFR 50.73(a)(2)(v)(C) as a condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material. U.S. NUCLEAR REGULATORY COMMlSSlON (1 -2001 )
LICENSEE EVENT REPORT TEXT CONTINUATION FAClLlTV NAME (1)
DOCKET NUMBER (2)
Palisades Nuclear Plant 05000-255 TEXT (If more space is required, use additional copies of NRC Form 366A) (1 7 )
EVENT DESCRIPTION
!I On January 19, 2007, with the plant in Model, a small service water [BI] leak (approximately 60 drops per minute) was identified in VHX-4 containment air cooler (CAC) [CLR;BK]. The leak was subsequently determined to be from a pin-hole in a single cooling coil tube at the H-bend fitting.
The CAC cooling coil is a part of the containment [NH] boundary, and is required to be structurally sound to ensure that post accident containment leakage will not exceed allowable leakage (La).
Therefore, Technical Specification (TS) Limiting Condition For Operation (LCO) 3.6.1, "Containment," is initially applicable for any through-wall defect noted in a CAC cooling coil.
Although the size of the identified pin-hole would not have challenged La, it was not possible to characterize the flaw using the criteria prescribed in American Society of Mechanical Engineers (ASME) Code Case N-513-1 to verify the operability of the cooling coil for post-accident conditions over the CAC's mission time.
" Therefore, this event is reportable in accordance with 10 CFR 50.73(a)(2)(v)(C) as a condition that iould have prevented the fulfillment of the safety function of structures or systems that are needed 11 to control the release of radioactive material.
Since VHX-4 has no safety-related cooling function, TS LC0 3.6.6, "Containment Cooling Systems" was not affected.
/ CAUSE OF THE EVENT I1 The probable cause of the through-wall flaw is loss of wall thickness due to flow induced erosion.
CORRECTIVE ACTIONS
/ VHX-4 was repaired using an ASME accepted method by plugging tubes to isolate the H-bend flaw. I1 Subsequently, VHX-4 was completely isolated by installing blanks on the service water inlet and individual cooling coil outlet flanges.
NRC FORM 3668 U.S. NUCLEAR REGULATORY COMMISSION (1 -2001 )
LICENSEE EVENT REPORT TEXT CONTINUATION
SAFETY SIGNIFICANCE
FACILIN NAME (1)
Palisades Nuclear Plant The safety significance of this occurrence is considered to be minimal. For a worst case failure of a single CAC cooling coil tube, analysis has determined that all on-site and off-site dose limits would continue to be met for the bounding postulated post-accident scenario.
05000-255
PREVIOUS SIMILAR EVENTS
TEXT (If more space is required, use additional copies of NRC Form 366A) (1 7 )
Licensee Event Report 05-006, "Inoperable Containment Due to Containment Air Cooler Through-Wall Flaws" Licensee Event Report 06-006, "Inoperable Containment Due to Containment Air Cooler Through-Wall Flaw" Licensee Event Report 06-008, "Inoperable Containment Due to Containment Air Cooler Through-Wall Flaw"