ML031740458
| ML031740458 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 06/20/2003 |
| From: | South Texas |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| Download: ML031740458 (65) | |
Text
Bottom Mounted Instrument Guide Tube Condition Z0 0
5 1
n (D
5/l/03 1
STP Participants Tom Jordan Mark McBurnett Steve Thomas Michael Lashley Bill Humble Ron Baker Wayne Harrison Joe Loya Ulhas Patil VP, Engineering & Tech Services Manager, Quality & Licensing Manager, Plant Design Test Engineering Supervisor NSSS Supervisor Materials Specialist Licensing Engineer Design Engineer Design Engineer 5/1/03 2
INTRODUCTORY REMARKS Mark McBurnett Manager, Quality & Licensing 5/1/03 3
Agenda Introductory Remarks Desired Outcomes and Background Discovery and Initial Investigation Cause Investigation Process NDE Action Plan Repair Options Schedule and Milestones Concluding Remarks Mark McBurnett Tom Jordan Steve Thomas Steve Thomas Michael Lashley Steve Thomas Mark McBurnett Mark McBurnett 5/1/03 4
DESIRED MEETING OUTCOMES and BACKGROUND Tom Jordan Vice President, Engineering & Technical Services 5/1/03 5
Desired Meeting Outcomes NRC fully informed about condition and current status NRC understands current plans for NDE NRC understands current repair options NRC understands the cause investigation process Key stakeholders identified STP clearly understands NRC questions and has an action to provide responses 5/1/03 6
Opening Remarks 5/1/03 7
April 12 - residue found on two of the 58 Bottom Mounted Instrumentation (BMI) penetrations.
5/1/03 8
What we saw:
A small amount of residue had accumulated approximately 90 degrees around the guide tubes at vessel Penetrations #1 and #46.
5/1/03 9
The BMI guide tubes measure ~1.5 inches outside diameter, The quantity of residue found on Penetration
- 1 is equivalent to about half of an aspirin (approximately 150 mg).
Penetration #46 had about 3 milligrams of residue.
5/1/03 10
Evaluation results Our initial sample results revealed boron in the samples. We reported to the NRC that we had potential reactor coolant leakage from these two penetrations.
5/1/03 11
Eliminating other possibilities Other sources such as leakage from the refueling cavity and the possibility of other materials containing boron (paint, etc.) were considered. After exhaustive chemical analysis, it was determined that the source of the residue was reactor coolant.
5/1/03 12
Our inspection process works We inspect the exterior of our vessel each time we shutdown for a refueling outage. Previous inspections did not reveal indications of seepage.
5/1/03 13
Prompt, Comprehensive Response
- We are currently employing a team of experts to assist in the evaluation and development of corrective actions.
- The unit will not be restarted until the root cause is determined and the condition has been repaired.
- Unit 2 has been inspected in the last six months with no noted anomalies.
5/1/03 14
Cooperative approach We will continue to work closely with the NRC, other stations' experts, specialty contractors, and industry agencies to complete our inspections, analyses, and repair development. We are confident that this cooperative effort will result in effective resolution of this issue and the resultant safe restart of Unit 1.
5/1/03 15
DISCOVERY and INITIAL INVESTIGATION Steve Thomas Manager, Plant Design 5/1/03 16
~ 12" Between Insulation and Head 5/1/03 17
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BOTTOM MOtJNT8I) INSTRUMENT6TI12ti 511103 18 I
5/1/03 19
Penetration Locations lt-,,,w_
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BMI Guide Tube r
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Guide Tube 5/1/03 22
Planned Inspection
- Normal planned inspection
- Inspection is proceduralized
- Inspection specifically looks for this condition
- We have been inspecting regularly since initial plant startup 5/1/03 23
Penetration #1 5/1103 24
Penetration #46 5/1/03 25
Penetration #1 After Cleaning 5/1/03 26
Initial Investigation
- All 58 guide tubes examined; no additional residue found
- Experts from four nuclear plants brought to STP
- EPRI experts contacted
- Samples tested at two independent offsite labs as well as onsite lab 5/1/03 27
Sample Analysis The samples contained lithium and boron.
The samples did not contain any iron.
5/1/03 28
Age of Deposits not present, therefore > 1 year i Ratio of Cs-1 34 to Cs-137 indicates 4 years 5/1/03
- Co-58 29
CAUSE INVESTIGATION PROCESS Steve Thomas Manager, Plant Design 5/1/03 30
Cause Investigation Process
- Possible causes Fabrication defect Lack of fusion
> Weld hot crack
- Fatigue
) Mechanical
> Thermal
Cause Investigation Process (cont'd)
- Failure scenario construction
- Root cause determination
- Identify generic implications for STP
- Identify corrective actions
- Analysis Repair Monitoring 5/1/03 32
Cause Investigation Process (cont'd)
- Implementation
- Effectiveness Review 5/1/03 330
NDE ACTION PLAN Michael Lashley Test Engineering Supervisor 5/1/03 34
Action Plan
- Determine NDE priorities Penetrations 1 & 46
> Determine throughwall leak path
) Find structurally significant flaws
> Find other flaws
, Assess wastage Other penetrations
)> Find structurally significant flaws
> Find other flaws
- Evaluate operating experience
- Work by MRP on CRDM head penetrations
- Worldwide experience 35 5/1/03
Action Plan (cont'd)
- Determine NDE capabilities Identified three experienced vendors Selected two vendors to demonstrate NDE capabilities
- Determine scope of inspections Guide tubes/penetrations
- Volumetric exam of tube
- Visual exam of J-groove weld 36 5/1/03
Action Plan (cont'd)
- Select approach that satisfies NDE priorities Select approach that is acceptable to the NRC
EPRI MRP Approach for CRDM nspections
- Define NDE objectives Identify relevant flaw mechanisms Define inspection locations and volumes Define range of flaws to address
- Mockup design and procurement
- Demonstration protocol and schedule Blind / non-blind Detection / sizing / location False calls 5/1/03 38
NDE Objectives
- Relevant flaw mechanisms PWSCC, fatigue, fabrication defects, etc.
- Inspection locations and volumes ID/OD of tube
- Tube to weld interface
- Weld surface
- Range of flaws 10%- 100%TW 0.25" - 0.50" length
- Axial / circumferential 5/1/03 39
Mockup Design and Procurement
- Full scale mockup Simulate outer periphery location Guide tube machined from Alloy 600 to match design Curved vessel dropout with machined penetration I J-groove
- Demonstration standards Simulate the inspection volume Contain range of ID/OD flaws 5/1/03 40
Mockup Design CIP-Coid Isostatic Processing
-Compresses the notch to produce crack-like defect
-Accurately controlled j;',
size, location, orientation
-Used n all MRP VHP NDE demonstrations 5/1/03 41
Demonstration Protocol
- Scope Detection and sizing of axial and circumferential flaws in the tube
> Isolated flaws
> Axial and circumferential flaws in conjunction
> ID and OD flaws Discrimination of flaws from sources of false calls Flaw locations relative to component geometry 511/03 42
Demonstration Protocol (cont'd)
Process - follows MRP process for VHP demos Phase 1 (open/non-blind)
) Allow refinement of procedures under realistic, controlled conditions
)> Allow analysis of results to determine ahd improve capabilities of individual techniques within the procedure
- Detection, sizing, location Phase 2 (monitored/blind)
> Demonstrates capability Detection, sizing, location 5/1/03 43
Demonstration Protocol (cont'd)
- Reporting Performance of inspection organizations will be documented to record the following parameters:
> Procedure identification, including essential variables
) Detection performance
> False call performance
> Sizing performance
>> Flaw location performance 5/1/03 44
Demonstration Schedule
- Schedule Procure/fabricate mockups
> Standards - in progress 5/1
> Mockup - in progress 5/9 Phase 1 (open/non-blind)
Vendor A 5/2 - 5/5
> Vendor B 5/2 - 5/5 Phase 2 (monitored/blind)
> Vendor A (US home office) 5/6 - 5/7 Vendor B (US home office) 5/8 - 5/9 5/1/03 45
Inspections
- Penetration 1 & 46 UT and/or ET from guide tube ID Enhance visual exam of J-groove weld surface
- Volumetrically interrogate vessel base metal for wastage
- Remaining penetrations UT and/or ET from the guide tube ID Enhance visual exam of J-groove weld surface 5/1/03 46
Inspection Equipment Borwo;!/,
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LOWER CORE PLATE GUIDE TUBE INSTRUMENTATION NOZZLE VESSEL BOTTOM INSPECTION AREA 5/l/03 47
Ultrasonic and Eddy Current Probes 48 I
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5/1/03
Inspection Tool and Operating Station 5/1/03 49
Inspection Tool 5/1/03 50
REPAIR OPTIONS Steve Thomas Manager, Plant Design 5/1/03 51
epair Options
- Half-nozzle
- Mechanical Nozzle Seal Assembly (MNSA)
- Encapsulation / Capped 5/1/03 52
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Half-Nozzle Repair Method
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Half-Nozzle
- New Alloy 690T nozzle
- Alloy 600 material no longer pressure boundary
- Temperbead pad
- Core offloaded with lower internals removed
- Thimble removed for repair
- Remote machining 5/1/03 54
MNSA Repair Method 5/1/03 55
MNSA
- No core impact
- Machine groove in Alloy 600 tube
- Restrains existing J-groove weld
- Drill/tap pressure vessel
- High "hillside" angle difficult to seal and induces bending moments 511/03 56
Encapsulation / Capped Repair Method PLuO A-1U ER lUI 5/1/03 57
Encapsulation I Capped
- Thimble removal required
- Limited scope repair
- Nozzle function lost
- Requires Temperbead pad and weld 5/1/03 58
Regulatory Review
- Use 10CFR50.59 to determine if license amendment required
- Relief request
SCHEDULE and MILESTONES Mark McBurnett Manager, Quality & Licensing 5/1/03 60
Outage Milestones
- Reactor disassembled; core offloaded -
mid-May
- Complete NDE and analysis - late May
- Design approval; relief request submittal -
early June
- Commence repairs - mid-June
- Final breaker closure - late Summer 5/1/03 61
Future Plans and Action Items
.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Meetings with NRC - next one proposed for week of May 26
- Weekly conference calls with NRC
- NRC inspections 5/1/03 62
CONCLUDING REMARKS Mark McBurnett Manager, Quality & Licensing 5/1/03 63
MEETING PARTICIPANTS FOR MEETING BETWEEN STPNOC AND NRC ON MAY 1. 2003 Participants Affiliation Michael Leishlear STP Ulhas Patil STP Ron Baker STP Bill Humble STP T. J. Jordan STP Steve Thomas STP Joe Loya STP Wayne Harrison STP Mark McBurnett STP Leonard Wert NRC Eric Reichelt NRC Matthew Mitchell NRC Edmund Sullivan NRC Keith Wichman NRC Jay Collins NRC David Terao NRC Stephen Monarque NRC Barry Elliot NRC Francis Grubelich NRC Donald Harrison NRC Mike Tschiltz NRC Veronica Klein NRC Jim Stmisha NRC Michelle Honcharik NRC Bart Fu NRC Steve Long NRC John Minns NRC DyLanne Duvigneaud NRC Steven Unikewicz NRC Bill Bateman NRC Edward Andruszkiewicz NRC Bill Reckley NRC Bob Gramm NRC Herb Berkow NRC Karen Gott NRC Mark Hartzman NRC Bob Davis NRC Rich Barrett NRC Donald Naujock NRC Steve Bloom NRC Ericlosure 2
Particinants Anthony Mendiola David Fischer Mohan Thadani Chris Gratton Jack Foster Eva Brown Scott Burnell Dwight Chamberlain Russ Bywater Alex Marion Jim Riley David Lochbaum Frank Ammirato Joe Roarty Toshiro Asakana Kazuo Fiujiki Taucher Jim Riccio Altheia Wyche Terry Pickens Daniel Horner David Udoff Deann Releigh Poo Yoon C. Brinkman Ed Spiegel Al Gutterman Al Butlauage Roger Huston Phillip Rush Dan Salter Leslie Spain NRC NRC NRC NRC NRC NRC NRC NRC NRC NEI NEI UCS EPRI DNFSB JAFRI JAFRI Taucher International Greenpeace SERCH Licensing/Bechtel Null Management Company McGraw-Hill Energy Intelligence Scientech KHNP Westinghouse Westinghouse Morgan, Lewis, & Bockius RGE Licensing Support Services MPR Associates HGP, Inc.
Dominion General Affiliation