ML091460685
| ML091460685 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 11/14/2008 |
| From: | Richmond J NRC Region 1 |
| To: | Baty M, David Pelton NRC Region 1 |
| References | |
| FOIA/PA-2009-0070 | |
| Download: ML091460685 (5) | |
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John Richmond I R-T Friday, November 14, 2008 2:36 PM Mary Baty; David Pelton DRAFT OC Preliminary Notification OC PNO-Nov-2008_Drywell_rev-i.doc High please provide any comments to me ASAP. We plan to issue this PN on Monday, Nov 17.
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([148.184.99.10]) with mapi; Fri, 14 Nov 2008 14:36:33 -0500 Content-Type: application/ms-tnef; name="winmail.dat" Content-Transfer-Encoding: binary From: John Richmond <John.Richmond@nrc.gov>
To: Mary Baty <Mary.Baty@nrc.gov>, David Pelton <David.Pelton@nrc.gov>
Importance: high Date: Fri, 14 Nov 2008 14:36:11 -0500
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DRAFT OC Preliminary Notification Thread-Topic: DRAFT OC Preliminary Notification Thread-Index: AclGkD94uMo76yOaRjaa9YrISXeSEw==
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Preliminary Notification DCS No.: 0500021911)XX08 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 Applicable..::.
Subject:
RESULTS OF IMPLEMENTATION OF "YSTER CREEK LICENSE RENEWAL COMMITMENTS RELATED TO THE PRIMARY CONTAINMENT
.(DRYWELL)
The NRC staff conducted an on-site inspection of ArerGen'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 involved a multi-week inspection of AmerGen's three aging managementprdgrams associatwith the primary containment (drywell): Containment Metallic Liner nsVic.
ipecton; Structures Monitoring Program; and Protective Coating Monitoring and Maintenance.4ggram. In-.acordance with the NRC's agreement with the State of New Jersey, State Engineers observe.portions of the NRC's staff I ativitieo, date, the NRC staff concluded review. Based on the resultsof-the NRC's inspecti 5ta there were no safety signi.ficant torditions withrsp mary containment that would prohibit plant startup.
OF' In the mid-i 980s, GPU-Nuclear (previous licensee)*1dentified corrosion of the drywell containment steel shell, in the sndbedeegieon. nhiLa licensee actions were not effective in arresting corrrsici. In 1992 all>snd was rem v6d from the sand bed region and the accessible exterior suirfces of the dryw sell were cleaned and coated with epoxy. Ultrasonic test,(UT) thickness*neasurements of the&rywell shell taken in 1992 and 1996 indicated the corrosion had bmeffectively arreste This hfor6mation was confirmed in 2006, during a refueling outage.
On OctobR 4, 2008, OCNGS shut down for a refueling and maintenance outage. Scheduled outage work included implem entation of various license renewal aging management programs.
During the 2008*hfuelingathoNRC's drywell shell inspection focused on:
- 1. Results of drywel1h ll 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 cavity onto the external surface of the drywell shell and into the sand bed regions.
Preliminary Notification 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 coatingin the sand bed regions, was acceptable, except for four small coating blisters found Il Bay-1 1. The blisters were repaired. AmerGen reported that some blistering was exp'ected, and would be identified during routine visual examinations. The NRC staff will review AmierGen's cause evaluation when it is complete.
- 4. The as-found condition of the external drywell shell moisture barrier sealbetween the shell and the sand bed floor, was acceptable, except for multiple surface cracks, which did not appear to completely penetrate the seal. The identified seal cracks were repaired. 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 leakag*from the reactor refueling cavity onto the external surface of the drywell shell and into'the sand bed regions was, in general, acceptable, with a few noted exceptibis-aas describedbelow.
On the fourteenth day of outage, water leakage&I-Iromte iect ug cavity into the cavity drain trough, as monitored in the trough's drain line, incpa from less than 1 gallon per minute (gpm) to approximately.to 7.gpm. -Si tehe cavity drain troughper appeared to occur, which restedri n,some waterentry into th sand bed region. AmerGen enhanced it's leakageom.
mitoring, re-opened all"&nd bed bays, and performed visual inspections to detec ay water ent Water puddles were identified in several sand bed bays.
Afte th cavty as% ined and the leaag After the cavity was dralakage stooppd, NRC and AmerGen performed direct inspections of the sandd bays-, no adaýrse conditions were identified. To determine whether any increase~dgr*/l sW];**
andyell shellcorroslon may have occurred, as a result of this leakage, AmerGen stated additkiaI TIth.ckness measurements would be performed in the next refueling outage, in 2010.r"A AmerGe**n.,identified and fixed problems found in sand bed Bay-3 and Bay-1 1, during license renewaltagirng managementprogram implementation. The drywell shell epoxy coating and the moisture banler seals, both in the sand bed region, are barrier systems used to protect the drywell shell from corrosion. The problems identified with these barriers had a minimal impact on the drywell IIsan thy smll ontedrw sneld t
,rojected shell corrosion rate remained very small.
Based on a review oft'h`technical information, the NRC staff determined AmerGen had an adequate basis to restirt 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
(*?nrc.gov (nrc.qov
Preliminary Notification (610) 337-5183 (610) 337-5220