ML091690480

E-mail from T. O'Hara of USNRC to Various, Regarding Oyster Creek Drywell Shell Coating Issue

ML091690480
Person / Time
Site:	Oyster Creek
Issue date:	11/03/2008
From:	O'Hara T NRC Region 1
To:	Conte R, Kaufman P, Richmond J, Jason White NRC Region 1
References
FOIA/PA-2009-0070
Download: ML091690480 (3)

Text

Sarah Rich From: Timothy OHara , F.

Sent: Monday, November 03, 2008 12:05 AM To: John Richmond; John White; Richard Conte; Paul Kaufman

Subject:

RE: Oyster Creek Drywell Shell Coating Issue John & All; (b)(5)

Tim OHara From: John Richmond Sent: Sunday, November 02, 2008 6:41 PM To: Marsha Gamberoni; Darrell Roberts; James Clifford; Ronald Bellamy; Richard Conte; Marc Dapas; John White Cc: David Pelton; Stephen Pindale; Justin Heinly; Jeffrey Kulp; Timothy OHara; Michael Modes; Glenn Meyer; Paul Kaufman

Subject:

Oyster Creek Drywell Shell Coating Issue OC License Renewal Outage Commitments Inspection Drywell Shell (steel liner) Coating Issue Exterior Drywell Shell in Sand Bed Bay 11 On Oct 31, during a routine coating inspection, AmerGen identified a coating defect. NDE VT Examination Record documented a "Pinhole Carbuncle, 1/4 inch in diameter, with Evidence of Leakage (Rust Line) 6 inches Long. 16 inches right of Opening [access tunnel], 34 inches from Moisture Barrier [floor in sand bed cavity]."

The carbuncle was verbally described as a small blister, soft to the touch. The leakage was verbally described as a "bleed through" 6" long tear drop shaped surfac6 stain, brownish in color, and dry to the touch.

A repair work order is being prepared. Repairs are scheduled for Nov 4. Per engineering specification, the coating defect will be removed using mechanical tools, such as pencil grinder, rotary file, flapper wheel, etc

[e.g., skill of the craft]. Prepare the substrate and feather the edges, then apply two layers of new coating

[Devoe epoxy]. The Issue.Report contains additional requirements, not yet in the work order, including (1) document the extent of the damage, and how deep the blister has formed into the coating, (2) verify plate thickness in the area of the coating failure meets acceptance criteria [e.g., do a UT from inside the drywell],

and (3) document with pictures as loose coating layers are removed.

The carbuncle, on the exterior surface of drywell shell, is very close to ultrasonic test (UT) location 1 1A, inside the drywell at elevation 11 ft. 3 in. UT location 1 1A is a 7x7 array (6"x6" grid). The carbuncle is located about 3 inches from a core plug that is in the 7x7 array. AmerGen estimates that the carbuncle is about 1 inch from the-edge of the array. Therefore, it's reasonable to expect that a good UT can be done from inside the drywell at the location of the defect outside the drywell.

Sand Bed Bays 1, 11, and 13 were previously identified as the bays with the most significant corrosion (e.g.,

thinnest shell). The epoxy coating system was applied in 1992, and was 3 layers thick. The total thickness is believed to be about 25 mils. The first post-installation coating inspection was last outage, in 2006. This is only the second coatings inspection since 1992. In 2006, no coating defects were identified. This outage (2008), only this one coating defect was identified.

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All sand bed bays have been NDE UT and VT examined this outage (not all NDE examination records have been prepared). No other potential coating defects were identified. Some cracks in the floor epoxy sealer and in the moisture barrier seal were identified, and are planned to be reworked.

On Oct 29 & 30 (prior to the defect being identified), Tim O'Hara inspected sand bed Bay 1, 5, 11, and 13.

Tim's inspection was not a full entry inspection; he did a general visual inspection from the tunnel opening, without entering the cavity. Tim did not identify any issues or concerns in bay 11, and only floor cracks in one nthpir bay were identified.

On Nov 2, I did a full entry inspection of Bay 11 & 13, which also extended partly into Bays 9 & 15. There appears to be 2 or 3 small carbuncles in a cluster, next to the one that's bleeding. The NDE tech, when interviewed, also described a cluster of carbuncles, although the NDE data sheet only described the largest one. I did not identify any other potential indications or problems.

John Richmond OC NRC Team Room 609-971-4830 2

Received: from R1CLSTR01.nrc.gov ([148.184.99.7]) by R1 MS01.nrc.gov

([148.184.99.101) with mapi; Mon, 3 Nov 2008 00:05:19 -0500 Content-Type: application/ms-tnef; name="winmail.dat" Content-Transfer-Encoding: binary From: Timothy OHara <Timothy.OHara@nrc.gov>

To: John Richmond <John. Richmond@nrc.gov>, John White <John.White@nrc.gov>,

Richard Conte <Richard. Conte@nrc.gov>, Paul Kaufman

<Paul. Kaufman@nrc.gov>

Date: Mon, 3 Nov 2008 00:05:17 -0500

Subject:

RE: Oyster Creek Drywell Shell Coating Issue Thread-Topic: Oyster Creek Drywell Shell Coating Issue Thread-Index:

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