ML091470371

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Draft Preliminary Notification of Event of Unusual Occurrence, PNO-1-08-XXX, Facility Amergen Energy Company, LLC, Oyster Creek, Subject - Results of Implementation of Oyster Creek License Renewal Commitments Related to the Primary Containm
ML091470371
Person / Time
Site: Oyster Creek
Issue date: 11/30/2008
From: Conte R, Richmond J
NRC Region 1
To:
References
FOIA/PA-2009-0070
Download: ML091470371 (2)


Text

N Preliminary Notification DCS No.: 0500021911XX08 Date: November XX, 2008 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO-1 XXX Facility Licensee Emergency Classification AmerGen Energy Company, LLC Notification of Unusual Event Oyster Creek Alert Forked River, New Jersey Site Area Emergency.

Docket: 50-219 General Emergency X Not Applicable _

  • Af

Subject:

RESULTS OF IMPLEMENTATION OFQY*,TER CREEK LICENSE RENEWAL COMMITMENTS RELATED TO THE PRIMARY CONTAINMEIIT (DRYWELL)

The NRC staff conducted an on-site inspection of AmerGen's actions related to license renewal commitments to be implemented during the 200 eling outae at the Oyster Credk Nuclear Generating Station (OCNGS). In particular, the NRC eievw invived a multi-week inspection of AmerGen's three aging management prgrams associct~ednwtoh the primary containment (drywell): Containment Metallic Liner 96.'e ce Inspection; S?'ýuctures Monitoring Program; and Protective Coating Monitoring and Maiitnct Program. Iacordance with the NRC's agreement with the State of New Jersey,,,tate*En-*i nirs observe'* portions of the NRC's staff review. Based on the results of the NRC'"ispectionactiities to date, the NRC staff concluded there were no safety signifid'a"nconditions with respec to the primary containment that would prohibit plant startup.

In the uclear (previous licensee) identified corrosion of the drywell containment steel shelliin the sand bed region. Initial licensee actions were not effective in arresting corrosion. Ir all sand was removedfom the sand bed region and the accessible exterior siurfaces of the dryweiI hell were cleanednd coated.with epoxy. Ultrasonic test (UT) thicknessurnts of the drywell shell taken in 1992 and 1996 indicated the corrosion had by arrested Thisinformation was confirmed. in 2006, during a refueling outage.

On October 24, 2008, OCNGS shut down for a scheduled refueling and maintenance outage.

Outage wor,,k included implementation of various license renewal aging management programs.

During the 2008 refueling outage, the NRC's drywell shell inspection focused on:

1. Results of dryv*elrshell UT thickness measurements.
2. Direct observatiodqVdrywell shell conditions both inside the drywell, including the floor trenches, and outside the drywell, in the sand bed regions.
3. Condition and integrity of the drywell shell epoxy coating, including AmerGen's activities to evaluate and repair four small coating blisters found in Bay-1 1.
4. Condition and integrity of the drywell shell moisture barrier seal between the shell and the sand bed floor, including AmerGen's activities to evaluate and repair identified cracks in moisture barrier seals in multiple sand bed bays, including a seal crack in Bay-3 which also exhibited small rust stains.
5. AmerGen's activities to monitor, evaluate, and mitigate water leakage from the reactor refueling cavity onto the external surface of the drywell shell and into the sand bed regions.

Preliminary Notification With respect to AmerGen's implementation of license renewal commitments, the NRC staff has concluded:

1. All drywell shell UT thickness measurements satisfied AmerGen's acceptance criteria and current licensing basis design requirements.
2. There were no identified significant conditions affecting the drywell shell structural integrity.
3. The as-found condition of the external drywell shell epoxy coating, in the sand bed regions, was acceptable, except for four small coating blisters found in Bay-1 1. The blisters were repaired. AmerGen reported that some blistering was expected, and would be identified during routine visual examinations. The NRC staff will review AmdrGen's cause evaluation when it is complete.
4. The as-found condition of the external drywell shell moisture barrier seal, between the shell and the sand bed floor, was acceptable, except for multipleSurfacecracks, which did not appear to completely penetrate the seal. The identified s**l cracks were repaired. During one crack repair, in Bay-3, some drywell shell surfa*ceerrosion was identified and repaired.
5. AmerGen's activities to monitor and mitigate water leakage from the reatar Irefueling cavity onto the external surface of the drywell shell aridinto the sand bed regionswere acceptable.

During the outage, water leakage from the reactor efueling cavityinto the cavity drain trough, as monitored in the trough's drain line, increased fromlss than1 allon per minute (gpm) to approximately 5 gpm. Some spill-over frm the cavity draintrough appeared to occur, which resulted in water entry into the sand be eig . AmerGeh ehanced its leakage monitoring and performed visual inspections to detect n waterentry. Water pddles were identified in several sand bed bays. After the cavity was draiie d, ,.beren perforrred direct inspections of the sand bed bays, and no adverse conditions weredentified. Todetermine whether any increased drywell shell corrosion may hav occurred as a res of this leage, AmerGen has committed to perform additional UT thicknessheasurem during the next refueling outage (2010).

AmerGen identified-and fixed the problems fou in sand bed Bay-3 and Bay-1 1, as part of their aging management p agrm implemetation The rywell shell epoxy coating and the moisture barrier seals, both in the sa d egi, rebarri4 systems used to protect the drywell shell from corrosion. The problm idntified wt -tljse barriers had a minimal impact on the drywell shell, an, the proJectad she** cor osion rate remains very small.

Based gn a review of the tchnical information, the NRC staff determined AmerGen has provi ed an adequate basis*o rest QONGS.

C The State of, ew Jersey hasbeen notified.

This Preliminary Notificationi being issued for information only and will not be updated.

ADAMS Accession Number: ML....................

CONTACT: Richard J. Conte John Richmond

@nrc..qov @nrc.gov (610) 337-5183 (610) 337-5220