ML020510559
| ML020510559 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 02/14/2002 |
| From: | Marschall C NRC Region 1 |
| To: | Ridenoure R Omaha Public Power District |
| References | |
| Download: ML020510559 (48) | |
Text
February 14, R. T. Ridenoure Division Manager - Nuclear Operations Omaha Public Power District Fort Calhoun Station FC-2-4 Adm.
P.O. Box 550 Fort Calhoun, Nebraska 68023-0550
SUBJECT:
FORT CALHOUN STATION - MEETING TO DISCUSS CONTROL ELEMENT DRIVE MECHANISM (CEDM) CRACKING ISSUES
Dear Mr. Gambhir:
This refers to the meeting conducted at Arlington, Texas, on February 8, 2002, between your staff and the NRC. The participants discussed the similarities and differences between Fort Calhoun Station and Palisades Station CEDMs.
The discussions included the actions you have taken and plan to take to ensure early detection and corrective action for potential cracks in the CEDM upper housing welds. Your staff agreed to provide the results of the examinations performed on drive housings during your next refueling outage.
The attendance list and presentation slides are enclosed with this summary (Enclosures 1 and 2, respectively).
In accordance with 10 CFR 2.790 of the NRC's "Rules of Practice," a copy of this letter and its enclosures will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records (PARS) component of NRCs document system (ADAMS). ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).
Sincerely,
/RA/
Charles S. Marschall, Chief Engineering Branch Division of Reactor Safety Docket: 50-285 License: DPR-40
Omaha Public Power District Omaha Public Power District
Enclosures:
- 1. Attendance List
- 2. NRC Presentation cc w/enclosures:
Mark T. Frans, Manager Nuclear Licensing Omaha Public Power District Fort Calhoun Station FC-2-4 Adm.
P.O. Box 550 Fort Calhoun, Nebraska 68023-0550 James W. Chase, Division Manager Nuclear Assessments Fort Calhoun Station P.O. Box 550 Fort Calhoun, Nebraska 68023-0550 David J. Bannister, Manager - Fort Calhoun Station Omaha Public Power District Fort Calhoun Station FC-1-1 Plant P.O. Box 550 Fort Calhoun, Nebraska 68023-0550 James R. Curtiss Winston & Strawn 1400 L. Street, N.W.
Washington, D.C. 20005-3502 Chairman Washington County Board of Supervisors Washington County Courthouse P.O. Box 466 Blair, Nebraska 68008 Sue Semerena, Section Administrator Nebraska Health and Human Services System Division of Public Health Assurance Consumer Services Section 301 Centennial Mall, South P.O. Box 95007 Lincoln, Nebraska 68509-5007
Omaha Public Power District Electronic distribution from ADAMS by RIV:
Regional Administrator (EWM)
DRP Director (KEB)
DRS Director (ATH)
Senior Resident Inspector (WCW)
Branch Chief, DRP/C (KMK)
Senior Project Engineer, DRP/C (vacant)
Staff Chief, DRP/TSS (PHH)
RITS Coordinator (NBH)
RidsNrrDipmLipb R:\\_FC\\2002\\fc2-8-02MS-cjp.wpd SRI:EMB C:EMB CJPaulk CSMarschall
/RA/ T
/RA/
02/11/02 02/14/02 OFFICIAL RECORD COPY T=Telephone E=E-mail F=Fax
ENCLOSURE 1 ATTENDANCE LIST Licensee:
D. Bannister, Plant Manager M. Frans, Manager, Nuclear Licensing W. Gates, Vice President, Nuclear R. Lisowyj, Senior Nuclear Design Engineer J. McManis, Manager, Design Engineering R. Phelps, Division Manager, Nuclear Engineering R. Ridenoure, Division Manager, Nuclear Operations K. Woods, Senior Nuclear Design Engineer NRC:
L. Berger, Branch Secretary K. Brockman, Director, Division of Reactor Projects (DRP)
A. Howell, Director, Division of Reactor Safety (DRS)
K. Kennedy, Chief, Projects Branch C, DRP C. Marschall, Chief, Engineering and Maintenance Branch, DRS E. Merschoff, Regional Administrator, Region IV C. Paulk, Senior Reactor Inspector, DRS W. Walker, Senior Resident Inspector A. Wang, Project Manager, Office of Nuclear Reactor Regulation L. Willoughby, Resident Inspector
ENCLOSURE 2 Licensee Presentation
Control Element Drive Mechanism Housing Reliability A presentation to the NRC by the Fort Calhoun Station Staff February 8, 2002, Arlington, Texas
Agenda
- Introductions - Gary Gates
- Agenda Review - Ralph Phelps
- Summary of Fort Calhoun Station Initiatives - Joe McManis
- CEDM Housing Mechanics Discussion -
Kirby Woods
Agenda
- CEDM Housing Materials Characterization Discussion - Bob Lisowyj
- Conclusions - Ralph Phelps
- Closing - Ross Ridenoure
Joe McManis, P.E. - Manager, Design Engineering Summary of Fort Calhoun Station Initiatives Regarding CEDM Reliability
Operating Experience
- CEDM Housing Assemblies
- Seal Housing
- J-groove weld
- Palisades 1986-1990 &
1999-2001
- Upper Housing
- Overlay weld
- FCS 1990
- V-groove weld
- Palisades 2001
- VHP Nozzles
- J-groove weld
- -INSIGHT-
- Performed
- Seal Housing
- Upper Housing
- Planned
- Seal Housing
- Program plan
- Upper Housing
- 10 yr ISI
- Commitments(1991)
- Perform HJTC housings UT (10 yr ISI)
- Clean/Visually Inspect RV Head FCS CEDM Inspections
VHP Nozzle
- Oconee 3 Event
- Circumferential Cracking
- Effective Full Power Year
- Time-at-Temperature Model
- Low Probability of Rupture and/or Excessive Leakage
- Effective Visual Inspection during May
FCS Susceptibility Assessment
- Environment
- Oxygen
- Stagnancy
- Residual Stress
- Longitudinal
- Circumferential
- Temperature
- Conclusion
- Seal Housing Highest Risk Susceptibility Assessment Description Environment Tensile Residual Stresses Temp.
Location Type Chlorides Oxygen Axial Hoop Seal Housing 1034'-7" j-groove High High Low High Moderate Upper Housing Autoclave Flange 1033'-9" double v-groove High Moderate Moderate1 N/A Moderate Upper Housing Pipe 1022'-4" overlay Low Low Moderate1 Low Moderate Modified Eccentric Reducer Large Diameter 1021'-8" double v-groove Low Low Moderate1 N/A Moderate Modified Eccentric Reducer Small Diameter 1021'-3" double v-groove Low Low Moderate1 N/A Moderate Note: 1 -
This moderate stress peaks at the weld root and dissipates within the weld area.
Key Differences
- Fort Calhoun Station has:
- Time
- CEDM through-wall cracks
- Operation
- Maintenance outage
- Thermal Sleeve
- Palisades extends to their reactor vessel flange
- Program Plan
Material Reliability Focus
- Operating Experience
- Seal Housing
- Upper Housing
- Program Plan
- Predictive and Environmental Model
- Inspection, Remediation and/or Repair Plan
- Overview of Issues
- Responses
- Actions
Introduction of Program Managers
- Two Individuals Providing Oversight of the Issue
- Kirby Woods - PE, MS, Worked on Issue since early 1998
- Bob Lisowyj - PhD, Worked on Issue since 1990
Kirby D. Woods - Senior Nuclear Design Engineer CEDM Housing Mechanics Discussion
CEDM - Seal Housing Assembly
- Longest Stagnant Area
- Oxygen
- Leachable Chloride
- Flexitallic gasket, o-rings and graphitar (~50 ppm)
- Residual Stress
- Fabrication Records
- Residual Stress (33 to 75 mils shrinkage)
- Temperature
- Operating Experience
- -PRECURSOR-
- Interpretation
- Residual Stress
- J-groove weld
- Transverse shrinkage
- Axial stress
- Temperature
- ~250º F/121 º C
- Palisades experience
- Inverted Bath Tub Curve CEDM - Seal Housing Assembly
CEDM - Seal Housing Assembly
- Weld Induced Shrinkage
CEDM - Seal Housing Assembly
- Longitudinal Driver
CEDM - Seal Housing Assembly
- Circumferential Driver
CEDM - Seal Housing Assembly
- Temperature Relationship
- Interpretation
- Residual Stress
- J-groove weld
- Transverse shrinkage
- Axial stress
- Temperature
- ~250º F/121 º C
- Palisades experience
- Inverted Bath Tub Curve CEDM - Seal Housing Assembly
- High Susceptibility
CEDM - Upper Housing Assembly
- Through-wall Crack 1990
- non-vented housing
- RC-10-9 & 13 Spare
- 100% stagnant
- Line B showing maximum level of stagnancy
- Source of Tensile Stress
- Overlay Weld
- -WORST CASE-
CEDM - Upper Housing Assembly
- Interpretation
- Residual Stress
- Overlay weld
- Double v-groove weld
- Weld pass
>> jacketed
- Temperature
- ~505ºF/263ºC
- FCS experience
- ~50 ºF delta
CEDM - Upper Housing Assembly
- Circumferential Driver
CEDM - Upper Housing Assembly
- Longitudinal Driver
CEDM - Upper Housing Assembly
- Through-Wall Affect
CEDM - Upper Housing Assembly
- Longitudinal Driver
CEDM - Upper Housing Assembly
- Circumferential Driver
CEDM - Upper Housing Assembly
- Temperature Relationship
CEDM - Upper Housing Assembly
- Interpretation
- Residual Stress
- Overlay weld
- Double v-groove weld
- Weld pass
>> jacketed
- Temperature
- ~505ºF/263ºC
- FCS experience
- ~50 ºF delta
- Medium/Low Susceptibility
Bob Lisowyj - Senior Nuclear Design Engineer CEDM Housing Materials Characterization Discussion
Program Plan
- Predictive
- Crack Model
- Environmental Model
- Plan
- Inspection Criteria
- Remediation
- Repair INNOVATIVE-
Predictive Crack Model
- Palisades and FCS Weibull Curves
- Material difference Type 304 versus Type 347
- FCS Upper Housing Beachmarks
- 10 yrs incubation & 7 yrs cracking
- -ANALYTICAL ASSESSMENT-FCS TGSCC Projections 0.00 0.20 0.40 0.60 0.80 0
5 10 15 20 25 30 35 Years of Operation (yrs.)
Crack Depth (inches)
FCS1990 Upper Housing (Actual)
Palisades 1999 Seal Housing (Actual)
Palisades Seal Housing (Positive Indications Projected)
FCS Weld Overlay Failure
- Six of Eight Inspected
- Permeability Change
- FCS and Palisades
- Similar
- Geometry
- Signatures
- Assessment
- Possible SCC History
- -INSPECTION DATA-1 26 51 76 101 126 151 176 201 0
20 40 60 80 100 120 140 160 Vert (ECU)
Circumferential (degrees)
RC-10-27 ECT Signature Depth
- Palisades ECT sample
- Positive Signatures
- Cracks
- Permeability Areas
- Positive Signatures
- Permeability Areas ECT Inspection Results
ECT Inspection Results
- -Palisades-
ECT Inspection Results
- -FCSs Difference-
- Palisades ECT sample
- Positive Signatures
- Cracks
- Permeability Areas
- Positive Signatures
- Permeability Areas ECT Inspection Results
- -QUESTIONING-
Sample
- EPRI assistance
- Validation of ECT technique
- Drive Housing Sleeve preparation for ATEM work
- - CONFIRMATION-Palisades Drive Housing Sleeve
Pacific Northwest Division (Battelle)
- Palisades Sample
- Seal housing
- SA312 F304
- Scanning Electron Microscope
- Transgranular
- Small Branching
- 0.095 deep
- Energy Dispersive Spectroscope
- Cl & S contaminants
- Fe,Cr & Ni oxides
2/08/02 OPPD Presentation 1
Pacific Northwest Division (Battelle)
I Palisades active housing
2/08/02 OPPD Presentation 2
Pacific Northwest Division (Battelle)
I Palisades active housing
2/08/02 OPPD Presentation 3
Pacific Northwest Division (Battelle)
I Palisades active housing I SEM/EDS Analyses N Impurities
! Na, Al, Si, Ca, K and Cl in spots N Oxides
! Si, S and Cl near crack tip
2/08/02 OPPD Presentation 4
Pacific Northwest Division (Battelle)
I Palisades active housing I TEM/EDS Analyses N 3 to 5 µm particles identified N Delta ferrite pattern
! Observation EDS Analyses: wt.%
Si Cr Mn Fe Ni matrix: 0.6 20.2 2 bal. 9.2 ferrite:
0.5 28.4 1.6 bal. 4.8 011 Plane