ML063420628
| ML063420628 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 10/24/2006 |
| From: | O'Hara T NRC/RGN-I/DRS/PSB2 |
| To: | Kaufman P NRC Region 1 |
| References | |
| %dam200701, TAC 8261 | |
| Download: ML063420628 (19) | |
Text
T0ithyoqH ara - Fwd: Slides
.page 1
From:
Timothy O'Hara To:
Kaufman, Paul Date:
10/24/2006 8:13:36 AM
Subject:
Fwd: Slides
- FYI, Tim O'Hara
Timothy O'Hara-SSlides Page 1 From:
<john.hufnagel @ exeloncorp.com>
To:
<tlol @nrc.gov>
Date:
10/23/2006 4:15:34 PM
Subject:
Slides
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Fwd: Slides 10/24/2006 8:13:36 AM Timothy O'Hara TLO I @nrc.gov Recipients nrc.gov kpl po.KPDO AM PDK (Paul Kaufman)
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Size 325 No None Yes Standard No None No Standard Immediate All Information
Tm0othy OHara-Comm Doc - Drywell Inspections[10-23-06 alexippt Oyster Creek IR21 Outage Communication Package Related to Drywell Shell Inspections October 23, 2006 Page 11
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PRELIMINARY I
JTimoth ý'Hara Comm Doc'- Drywell,IspIection-s1-23-06 aex.ppt Page2 pt 1R21 Drywell Inspections
- Reactor Cavity Trough Drain Line
" Sand Bed Region Poly Bottles
- Sand Bed Drain Lines
" Epoxy Coating on External Surface of Drywell Sandbed in all 10 Bays
- Internal Drywell Shell in Sand Bed Region Above Floor Elevation
- Internal Drywell Shell in Upper Regions
- Seal at the junction between drywell shell and concrete floor in Sand Bed Region
" External Drywell Shell in Sand Bed Region
- Plate Thickness Transitions at Two Elevations
" Internal Drywell Shell in Trenches (Bays 5 and 17)
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PRELIMINARY 2
Timothy O'Ha-a - Comm Doc - Drywell Inspections 10-23-06 alex.ppt Page3 Inspection Status (To Date)
The reactor cavity trough drain line is not clogged and is successfully removing a small amount of water entering the trough. Daily water leakage monitoring continues (as planned, strippable coating was applied to reactor cavity before flood-up).
There has been no water observed in the Sand Bed Regions and no water coming down through the air gap.
" There has been no water leakage from the Sand Bed Regions confirmed by the absence of water in the poly bottles. Daily monitoring of the poly bottles continues.
Two of the five Sand Bed drain lines were found to have some blockage and debris. These will be cleaned prior to restart.
" The visual inspection of the epoxy coating on the external shell surface in the Sand Bed regions has been completed.
- The seal at the junction of the drywell shell and the concrete floor in the Sand Bed region has been inspected.
<date>
PRELIMINARY 3
Timothy OHara - Comm....
.Page4]
Inspection Status (To Date)
- The Ultrasonic Inspections of the Interior Surface of the Drywell in the Sand Bed regions have been completed.
- The Ultrasonic Inspections of the Interior Surface of the Drywell in the Upper regions are in progress.
- The Ultrasonic Inspections of the Exterior Surface of the Drywell in the Sand Bed regions are completed.
- The Ultrasonic Inspections of the plate thickness transitions at two locations are in progress.
- The Ultrasonic Inspections of the Interior Surface of the Drywell in the Trenches in Bays 5 & 17 have been completed.
<date>
PRELIMINARY 4
Timothy O'Hara - Co-m-m Doc - Dryw!e Inspecttions 10-23-06a!expp.
Page 5'.
Issues Identified
- Standing water was identified in the trench inside the Drywell at the Drywell floor level in Bay 5 when the foam fill was removed for planned inspections.
- Dampness was identified in the other trench in Bay 17; however, no standing water was present.
- The Drywell drain trough may be a contributor to water leakage into the trench in Bay 5.
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PRELIMINARY 5
'Hara - Comm Doc - Drywell lpspeýfior?ý alex.ppý
ýge I Timothy QHara - Comm Doc - Dryweli Inspections 10-23-06 alex.ppt Page Water in Bay 5 Trench Description of Findings and Actions to Resolve this Issue
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PRELIMINARY 6
Timiotýhy O'Hara --Comm Doc-Drywell Inspections-10-23-06 alex.ppt Page 71I Issue Description
" When performing planned Non Destructive Examinations of the Drywell Shell from inside the Drywell, water was found in a trench area below the floor elevation.
" A similar condition was identified in the mid 1990s and documented in the corrective action process.
" The source of this water needs to be understood and addressed, and any impact on the drywell shell or concrete evaluated and addressed.
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PRELIMINARY 7
TimothyOHara - Comm Do: P_-rywel! !nspections 10-23-06 alex.ppt Page 8 Drywell Design and Layout
" The Drywell floor drain sump is located within the under-vessel area room
" A concrete trough encircles the under-vessel area to channel any leakage in the drywell to the drywell sump
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PRELIMINARY 8
LTimothy O'Hara-Comm Doc-Drywell Inspections 10-23-06 alex.ppt I
Page 91 Sketch Showing Lower Drywell - Sandbed, Trench and Sump 4
1: Tim-oth.y-O'Hara Comm Doc - Drywell Inspections 10-23-06 alex.ppt Pag~e 10!1 I Timothy OHara - Comm Doc - Dryweli Inspections 10-23-06 alex.ppt Page lOfj Trench Detail Sketch LIGHT OENSITY SILICONE I Nc.
DRYTWELL VARIES CROSS-SECTION AREA OF TRENCHES IN BAYS 5 & 17
[ T66thy O'Hara - Comm'Doc -'Drywell Inspections 10-23-06 alex.ppt
.1.
1 1 Page 111 F
Timothy OHara - Comm Doc - Drywell Inspections 1 0-23-06 alex.ppt Page 11 Plan View of Trough and Trenches
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11 KEY PLAN
T!mothy OHara -CommDoc, Drywell Inspections 10-23-06 a!eýx.ppý.t Page 12I Top View - Drywell Floor Sketch 12
Timothy O'Hara -Comm Doc,- Drweinpec~tions 10-23-06 alex.ppt P.age 131 As Found Condition 0 Surface of drywell shell visible from trenches in Bays 5 and 17 exhibited a surface layer of iron oxide
- Approximately 5" of water found in bottom of trench in Bay # 5, and trench in Bay 17 had only dampness
- Connection between under-vessel area trough and floor drain sump potentially allowing water leakage
" Trough located in the under-vessel area is not lined, potentially allowing water passage into the concrete slab
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PRELIMINARY 13
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Investigative/Corrective Actions Completed
" Visual inspections and pictures taken of sump, trough and trench areas
" Visual and Ultrasonic examinations of drywell shell in trench areas (as originally planned)
" Chemical Analysis of water samples from trench, sump and other areas
" Correlation and evaluation of water levels in sump, trough and trench areas
<date>
PRELIMINARY 14
ITimth;y OHara' Co6mm Dc-rwI npcin 02-6ae~p Actions Planned/Pending
- Visual Examination (VT-1) of floor drain sump liner to look for evidence of a leak path
- Tracer test aimed at determining whether under-vessel trough is in communication with trench in Bay 5
- Development of contingency repair to trough to address likely water source into trench
" Complete non destructive examination and analysis of Drywell shell in trench areas
- Perform evaluation of the impact of water that may exist beneath concrete surface on drywell shell
" Development of contingency repair to caulk intersection of Drywell Shell and concrete slab curb
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PRELIMINARY 15
Tim*othy o;Hara -Comm Doc-D, rel1 Inspections 10-23-06 aex.ppt "Page 16 Current Conclusions Preliminary Inspection Results indicate that the Drywell Shell
- Retains its structural integrity
- Provides margin to design safety function
- Supports plant operation for the period of extended operation
<date>
PRELIMINARY 16