ML091480444

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

ML091480444
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: ML091480444 (3)

Text

i.-4 Preliminary Notification G:\DRS\Engineering Branch 1\_LicRenewal\Oyster Creek\2008 Outage\Backup\OC PNO Nov-2008_Drywellrev-l.doc DCS No.: 05000219110XX08 Date: November XX, 2008 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO-1-08-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 Applicabl .

Subject:

RESULTS OF IMPLEMENTATION OF OYSTER CREEK LICENSE RENEWAL COMMITMENTS RELATED TO THE PRIMARY CONTAINMENT (DRYWELL)

The NRC staff conducted an on-site inspection of ArnerGen's actions related to license renewal commitments to be implemented during the 2008 refueling outage at the Oyster Creek Nuclear Generating Station (OCNGS). In particular, the NRC review *nvolved a multi-week inspection of AmerGen's three aging management progra*ns associated with the primary containment (drywell): Containment Metallic Liner Inservice Inspection; Structures Monitoring Program; and Protective Coating Monitoring and Maintenance Program. In accordance with the NRC's agreement with the State of New Jersey, State Engineer s)Pberved portions of the NRC's staff review. Based on the resultsof the NRC's inspection activities to date, the NRC staff concluded there were no safety si'nificant conditions with respect to the primary containment that would prohibit plant startup.<

In the mid-1 980s, GPU Niclear (p'revi'ous licensee) identified corrosion of the drywell containment steel shell, in the sand bed egion. Initial licensee actions were not effective in arresting corrosion. In 1992, all sand was removed from the sand bed region and the accessible exterior sufaces of the dry-welshell were cleaned and coated with epoxy. Ultrasonic test (UT) thick*ess measurementsrof the dayweli shell taken in 1992 and 1996 indicated the corrosion had been effectively arrested. This inforna:tion was confirmed in 2006, during a refueling outage.

On October 24, 2008, OCNGS shut down for a refueling and maintenance outage. Scheduled outage work inc**ded implenmentation of various license renewal aging management programs.

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

1. Results of drywell shell UT thickness measurements.

2. Direct observation of drywell 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, mitigate water leakage from the reactor refueling

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Preliminary Notification cavity onto the external surface of the drywell shell and into the sand bed regions.

On a sampling basis, the NRC staff had the following observations of Amergen's implementation of license renewal commitments, during the 2008 refueling outage:

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.

As described below, there were several problems identified during AmerGen's implementation of license renewal commitments.

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, nd would be identified during routine visual examinations. The NRC staff will1review AmerQIn s cause evaluation when it is complete.

4. The as-found condition of the external drywellshell, moisture barrier seal between the shell and the sand bed floor, was acceptable, exxcqdfor multiple surface cracks, Which did not appear to completely penetrate the seal. The~idlntified seal cracks were repair>&d. During one crack repair, in Bay-3, some drywell shell surface corrosion was identified and repaired.

5. AmerGen's activities to monitor and mitigate water lea~kagefrom the reactor refueling cavity onto the external surface of the drywellt/shell and intothe sand bed regions was, in general, acceptable, with a few noted exceiti*o*ný a below.

.described On the fourteenth day of outage, water leakage froI the reactorrefueling cavity into the cavity drain trough, as monitored in theetrough's drain line icreased- from less than 1 gallon per minute (gpm) to approximately 5.to 7 gpm. Sm**e ll-over freom the cavity drain trough appeared to occur, which resulted n some wat entry into the sand bed region. AmerGen enhanced it's leakage monitoring, renopened all'sand bed bays, and performed visual inspections to deect*aany water enty. Water pud dles were identified in several sand bed bays.

After the cavity was drained and e.aleakage.stoppl, NRC and AmerGen performed direct inspections of the sand bedbys, no adaversgemonditions were identified. To determine whether any increased*,.*.eshei cO*6sion may have occurred, as a result of this leakage, AmerGen stated additional UM.ti"knessr asurements would be performed in the next refueling outage, in 20, *1L AmerGe, identified and fixgd problemr found in sand bed Bay-3 and Bay-i 1, during license renewal ag]panagement program implementation. The drywell shell epoxy coating and the moisture barniýeseals, both ie sand bed region, are barrier systems used to protect the drywell shell frofm crrosion. The problems identified with these barriers had a minimal impact on the drywell shel11' d theprojected shell corrosion rate remained very small.

Based on a review of the technical information, the NRC staff determined AmerGen had an adequate basis to restart OCNGS.

The State of New Jersey has been notified and no further updates are planned.

This PN is being issued for information only and will not be updated.

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

CONTACT: Richard J. Conte John Richmond

Preliminary Notification

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

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