ML091980506
| ML091980506 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 11/05/2008 |
| From: | Richmond J Division of Reactor Safety I |
| To: | Bellamy R, Conte R, Gamberoni M, Heather Jones, Meyer G, David Pelton, Darrell Roberts NRC Region 1 |
| References | |
| FOIA/PA-2009-0070 | |
| Download: ML091980506 (4) | |
Text
Marsha Gamberoni From: John Richmond Sent: Wednesday, November 05, 2008 8:29 PM To: Richard Conte; Darrell Roberts; Ronald Bellamy; David Pelton; Glenn Meyer; Heather Jones; Marsha Gamberoni Cc: Jeffrey Kulp; Stephen Pindale; Michael Modes; Glenn Meyer; Marjorie McLaughlin; Justin Heinly; Timothy OHara; Diane Screnci; Joseph Schoppy
Subject:
OC LRI Daily Update Nov 5 OC LRI Outage Commitments Inspection Day 9 (Wednesday)
Darrell Roberts and Rich Conte were on-site today.
Schedule Change for Exit Meeting Thursday, Nov 6'-wITIe a no 1 07 598 9 NMI!
oil Monday, Nov-10 . ..... . from Region [time to be determined]
Drywell Structural Integrity Issues or Concerns
- 1) Repairs started for Sand Bed Bay-1 1 (exterior drywell shell). Within a small area, 4 distinct rust spots were exposed during excavation of 1 loose blister.
SEE SEPARATE E-MAIL FOR DETAILS
-I Inspection Progress
- 1) Progress remains painfully Slow. Most of the NDE W needed for our ii -eviw is expeut.
Today'sVl 1 ,ýX... tII ItIvv
',)1) O2 j2 coating repairs in Bay-11.
LR Commitment Issues or Concerns
- 1) An open question with NRR could result in an Inspection Report Open Item, such as an Unresolved Item
'URI' 54 2.11 clquire.q an nnnual update to the LR ADplication, until completion of the NRC reviewl (b)(5)
]AmerGen's last update was July 2007, more than a year ago. (b)(5)
NJ State Interface Remains Good. Rich Pinney seems satisfied. Interestingly enough, Rich continues to say that he believes there is no active (on-going) drywell shell corrosion, but he also seems worried that Exelon's monitoring of the drywell may be insufficient. Ron Zak agrees that a 1/4 inch diameter of rust has no impact on the structural integrity of the drywell, but still seems to believe the existing coating is not acceptable. Both Rich and Ron think AmerGen should be REQUIRED to do a 100% coating inspection every outage.
Team Location: OCAB 2nd Floor, Visiting Exec Office, 609-971-4830 e-,eJ , I 1Insuaodwuduie ,dm.
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Marsha Gamberoni From: John Richmond Sent: Wednesday, November 05, 2008 9:02 PM To: Marsha Gamberoni; Darrell Roberts; Ronald Bellamy; Richard Conte; David Pelton; Mary Baty; James Davis; John White Cc: Stephen Pindale; Justin Heinly; Jeffrey Kulp; Timothy OHara; Michael Modes; Glenn Meyer; Paul Kaufman; Heather Jones
Subject:
Oyster Creek Drywell Shell Coating Issue Oyster Creek Drywell Sand Bed Bay 11 Coating Defects Nov 5 merGen initiated their repair plan this evening. The one loose W previously identified by AmerGen was
,along wi M identified by NRC inspection. 1l -*
" The 4 locations are within a 1 to 2 inch oval of each other. The 3 bumps, which AmerGen initially characterized as surface irregularities, were tightly adhered, and were difficult to "pop off" (e.g., the technician said it took a lot of force to dislodge them). The blister was easily removed intact. The exposed drywell shell (4 locations) was lightly sanded, generally resulting in a clean bright metal surface. Mal/
The original
- W, about 6 inches long, was §1tpflW, and the scrapings collected into a bag for lab analysis. T I, originally described as a mante, was collected mostly intact, also for4,,
AmerGen's coating expert, Jon Cavallo, Corrosion Control Consultants & Labs, described the three layer coating as follows: (1) a clear primer, (2) a reddish brown epoxy layer, applied by roller, and (3) a grayish white epoxy layer applied by roller. Jon believes that the 2 epoxy layers should be 6 to 10 mils each, and that the three layer coating system would therefore be 12 to 18 mils in thickness. As a comparison, Jon said that a normal piece of copy paper is about 3 mils thick, so he expected the total coating thickness to be equivalent to about 3 sheets of paper. Jon believes the lab analysis will adequately determine the coating thickness of the collected scrapings and samples.
John Richmond From: John Richmond Sent: Monday, November 03, 2008 7:51 PM To: Marsha Gamberoni; Darrell Roberts; Ronald Bellamy; Richard Conte; David Pelton; Mary Baty; James Davis; John White Cc: Stephen Pindale; Justin Heinly; Jeffrey Kulp; Timothy OHara; Michael Modes; Glenn Meyer; Paul Kaufman
Subject:
RE: Oyster Creek Drywell Shell Coating Issue Summary of Conference Call between Exelon and NRC staff, regarding OC Drywell Sand Bed Bay-1 1 repair plans.
During an interactive discussion (questions and answers), Exelon Stated:
- 1) Detailed plan is still being developed, which will include:
- a. Opportunities for NRC observations during excavation and examination of the defect
- b. Chemical analysis to attempt to determine whether the surface stain contains iron
- c. Will carefully remove top loose layers to help determine whether there is any on-going drywell shell corrosion 1
- d. Will excavate an area maybe an inch in diameter, which should include any very close surface irregularities
- 2) No additional extent-of-condition was needed, to determine whether there are any blisters (carbuncles) in any other areas or other sand bed bays. A 100% coating examination had already been performed and no other defect or indication had been identified.
- 3) There is only one blister (about 1/4 inch in diameter), as documented on the VT-1 Examination Record.
There are no other blisters or carbuncles, as suggested by the NRC inspection of Nov 2. The inspector's observations must have been "bumps" that are just surface irregularities.
- 4) The coating has no service life. Epoxy coatings at some nuclear plants have been in-service, without any significant failures, for about 40 years. In non-nuclear industry, epoxy coating service life is typically an economic issue, and those coatings are often in very severe environments.
- 5) Some type of industry standard adhesion test might be done around the indication, prior to re-applying the new coating. A Dolly Adhesion Test [??] was considered too hard to perform. However, a modified knife edge test might be doable.
- 6) An ultrasonic test (UT) will be performed (maybe tonight), from the inside of the drywell, at the location of the coating defect.
If I left anything out, please feel free to add it in.
John Richmond 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 surface 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 2
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.
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 other 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 3