Deficiency Rept:Defects in Toe of Ring Beam Attachment Weld. Cracks Caused Hydrogen Cracking,Characterized by Intergranular Fracture of Course Grained Haz.Corrected by Grinding & New Welding ProceduresML19282A035 |
Person / Time |
---|
Site: |
Fermi ![DTE Energy icon.png](/w/images/5/5b/DTE_Energy_icon.png) |
---|
Issue date: |
04/19/1979 |
---|
From: |
DETROIT EDISON CO. |
---|
To: |
|
---|
Shared Package |
---|
ML19282A033 |
List: |
---|
References |
---|
EF2-46-133, NUDOCS 7905090355 |
Download: ML19282A035 (3) |
|
Similar Documents at Fermi |
---|
Category:DEFICIENCY REPORTS (PER 10CFR50.55E & PART 21)
MONTHYEARNRC-97-0141, Deficiency Rept Re Malfunction of EDG Number 11 Automatic Voltage Regulator (AVR) Printed Circuit Board Rev B,Due to Failure of Operational Amplifier U8 Chip.Avr Board Rev B Was Sent Offsite to Independent Engineering Facility1997-12-23023 December 1997 Deficiency Rept Re Malfunction of EDG Number 11 Automatic Voltage Regulator (AVR) Printed Circuit Board Rev B,Due to Failure of Operational Amplifier U8 Chip.Avr Board Rev B Was Sent Offsite to Independent Engineering Facility ML20211M6491997-10-0808 October 1997 Addenda 1 to Part 21 Rept Re Weldments on Opposed Piston & Coltec-Pielstick Emergency stand-by Diesel gen-set lube-oil & Jacket Water Piping Sys.Revised List of Potentially Affected Utils to Include Asterisked Utils,Submitted ML20211H7911997-09-30030 September 1997 Part 21 Rept Re Failure of Weldment Associated w/lube-oil Piping Sys on 970804 at Millstone,Unit 2.Root Cause Is Not Yet Known.Quality of Weldment Is Being Considered.Listed Util Sites Affected NRC-97-0005, Part 21 Rept Re 961113,EDG 11 Failed Surveillance Test 24.307.01 for LOP Coincident W/Loca.Avr Board Rev B Was Sent Offsite to an Independent Engineering Test Facility. CA Include More Analysis & Testing of AVR Board1997-02-0606 February 1997 Part 21 Rept Re 961113,EDG 11 Failed Surveillance Test 24.307.01 for LOP Coincident W/Loca.Avr Board Rev B Was Sent Offsite to an Independent Engineering Test Facility. CA Include More Analysis & Testing of AVR Board NRC-94-0072, Part 21 Rept Re Improper Installation of Thermo-Lag Fire Barrier Matl Furnished & Delivered by Thermal Science,Inc. Eight of Ten Thermo-Lag Fire Barriers Installed by Pr Sussman Co Being Replaced1994-08-15015 August 1994 Part 21 Rept Re Improper Installation of Thermo-Lag Fire Barrier Matl Furnished & Delivered by Thermal Science,Inc. Eight of Ten Thermo-Lag Fire Barriers Installed by Pr Sussman Co Being Replaced ML20070H1471994-07-15015 July 1994 Part 21 Rept Re Problems W/Thermolag Fire Barriers.Initially Reported on 940715.Replaced Thermolag Fire Barriers ML20059H7721994-01-17017 January 1994 Part 21 Rept Re Virginia Power Notifying Fairbands Morse Via Failure Analysis Rept NESML-Q-058 of Defective Air Start Distributor cam,16104412 ML20059F2631994-01-0707 January 1994 Part 21 Rept Re Air Start Distributor Cam Mfg by Fairbanks Morse.Mfg Suggests That Site Referenced in Encl App I Inspect Air Start Distributor Cam as Soon as Practical ML20058G5981993-11-17017 November 1993 Part 21 Rept Re Westronics Recorders,Model 2100C.Signal Input Transition Printed Circuit Board Assembly Redesigned to Improve Recorder Immunity to Electromagnetic Interference.List of Affected Recorders & Locations Encl ML20057G1511993-10-0707 October 1993 Part 21 Rept Re Westronics Model 2100C Series Recorders. Informs That Over Several Tests,Observed That Recorder Would Reset During Peak Acceleration & Door Being Forced Off Recorder.Small Retaining Clips Added to Bottom of Door ML20102B2071992-06-24024 June 1992 Part 21 Rept Re Cracking of Stellite 21 Hardfacing on Guide Nose of Poppets Supplied as Part of MSIV Leakage Improvement Mod.Initially Reported by Clei on 920522. Recommends That Liquid Penetrant Exam Be Performed ML20090L8801992-03-18018 March 1992 Part 21 Re Cracked Piston Castings Received from Acme Foundry,Fairbanks Morse & General Casting.Magnetic Particle Insp of All Pistons Will Be Performed.List of Affected Plants Encl ML20059M1751990-09-24024 September 1990 Supplemental Part 21 Rept 1 Re Defect in Coltec Industries, Inc Connecting Rod Assemblies Nuts/Bolts on Model 38TD8-1/8 Emergency Generators.Initially Reported on 851120.Nuts/bolts for Assemblies at Stated Plants Inspected & Replaced ML20011F1941990-02-22022 February 1990 Part 21 Rept Re Abb 27/59 Relay Catalog Series 211L.Solder Connections to Printed Wiring Runs on Bottom of Circuit Board Deteriorated Due to Thermal Stress.No Actual Failure Occurred & Relays to Be Changed at Next Outage ML20011F5971990-02-22022 February 1990 Part 21 Rept Re Solder Connections in Abb 27/59 Relays Deteriorated Due to Thermal Stress,Causing Bonding of Printed Wiring Pattern to Glass Epoxy Circuit Board.Interim Circuit Board W/Larger Pads & Higher Wattage Will Be Used NRC-89-0267, Deficiency Rept Re Item 143 on as-built Deviations.Qa Audit Conducted on Category C Deviations in Sept 1989.Remaining Category C Deviations Resolved During Refueling Outage1989-11-30030 November 1989 Deficiency Rept Re Item 143 on as-built Deviations.Qa Audit Conducted on Category C Deviations in Sept 1989.Remaining Category C Deviations Resolved During Refueling Outage ML20196B8481988-01-29029 January 1988 Part 21 Deficiency Rept Re HPCI Suction Pipe Overpressure Transient.Initially Reported on 880129.Caused by Installation of Lift/Plug Check Valve.Potential Water Hammer Condition Corrected by Replacing Valve NRC-87-0259, Part 21 Rept Re Unqualified Kalrez Soft Seats Used in Feedwater Check Valves Supplied by Atwood & Morrill Co. Initially Reported on 871203.Soft Seats for Valves Replaced W/Soft Seats Using Parker Compound E692-751987-12-0808 December 1987 Part 21 Rept Re Unqualified Kalrez Soft Seats Used in Feedwater Check Valves Supplied by Atwood & Morrill Co. Initially Reported on 871203.Soft Seats for Valves Replaced W/Soft Seats Using Parker Compound E692-75 NRC-87-0105, Part 21 Rept Re Failures of Hydrogen/Oxygen Sampling Sys Supplied by Exo Sensor,Inc.Initially Reported on 870630. Sensors to Be Replaced at 6-month Intervals & Tested Every 30 Days to Ensure Operability1987-07-0606 July 1987 Part 21 Rept Re Failures of Hydrogen/Oxygen Sampling Sys Supplied by Exo Sensor,Inc.Initially Reported on 870630. Sensors to Be Replaced at 6-month Intervals & Tested Every 30 Days to Ensure Operability ML20215G2441987-06-16016 June 1987 Part 21 Rept Re Failure of Load Sequencing Equipment Supplied in Aug 1977 During Scheduled Testing.Caused by Open Electrical Connection on One Crimp Lug.Since 1978,insulated Lugs Used on All Equipment ML20211P7211987-02-23023 February 1987 Part 21 Rept Re Rockbestos Coaxial Cable Used in Sorrento Electronics Digital & Analog high-range Radiation Monitor. Insulation Resistance at High Temp Not High Enough for Ion Chamber & Associated Electronics to Operate Properly ML20206S0841986-06-30030 June 1986 Part 21 Rept Re Possible Cut Wires in Wire Harness of Bbc Brown Boveri K600/K800 Circuit Breakers.Initially Reported on 860509.Safety Implications Listed.Gear Guard Designed to Prevent Cut Wires ML20211D8351986-06-0606 June 1986 Part 21 Rept Re Failure of Four External Closing Springs on MSIVs Supplied to Plant Due to Quench Cracks Developed During Mfg Process.Encl List Details Utils,Plants & Quantity & Size of Valves Supplied ML20195E4881986-05-23023 May 1986 Part 21 Rept Re Potential Failure of Ite/Gould Disconnect Switch,Type 7860 Ds Series.Instructions for Verification of Proper Operation of Switches Included in Notification to Plants.New Switches Available by 860901 ML20141A2501986-02-25025 February 1986 Part 21 Rept Re Two Broken Carrier Assemblies from NEMA Size 5 Contactor A103G12,preventing Proper Closing of Contactor. Breakage Believed Due to Dropping Device in Shipping Carton. Packaging Modified as of 860205 ML20151X3641986-01-30030 January 1986 Revised Page 3-4 to Attachment 3 to Deficiency Rept Re Traversing in-core Probe Nitrogen Purge Line Isolation & RWCU Sys Mods.Detailed Review of Potentially Overloaded Embedments Continuing & Will Be Completed Prior to Restart ML20138P0281985-12-13013 December 1985 Part 21 Rept Re Defect Identified in Two Oxygen Sensors. Added Thickness of Matl Will Eventually Cause Failure in Diffusion Membrane of Sensors.Sensors in Field Replaced ML20137S4441985-11-26026 November 1985 Part 21 Rept Re Unparallel Fitup of Nut to Mating Surface of Connecting Rod Cap & Nonperpendicular Faces of Nuts to Thread Pitch Line.Nuts & Bolts in Assembled Calvert Cliffs Onsite Spare Engine Will Be Replaced ML20198C8601985-10-23023 October 1985 Amended Final Deficiency Rept,Item 116 Re Potential Design Defect Which Allowed Freezing of Buried Piping Sys.Initially Reported on 840131.Constant Flow of 0.1 Gpm Through Affected Fire Protection Lines Will Be Maintained ML20210G9921985-08-13013 August 1985 Part 21 Rept Re Failure of Isolated Worm Shaft Gear When Certain Critical Speeds Combined W/Repetitive Transfer of Actuator Clutch Mechanism from Manual (Handwheel) to Motor Drive Mode.Two Possible Solutions Noted ML20099M1751985-03-0606 March 1985 Revised Final Deficiency Rept,Item 101 Re Debris in Piping Sys.Initially Reported on 850114.Items Removed & Safety Analysis Performed ML20108D5681985-03-0606 March 1985 Suppl to Final Deficiency Rept,Item 146,re Failure of Emergency Diesel Generators 11 & 12.Actions Taken to Minimize Stress & Deterioration of Bearings.Operating Procedures Modified & Quarterly Oil Filter Checks Planned ML20107K4701985-02-16016 February 1985 Final Deficiency Rept,Item 143 Re Deviations in Instrument Racks from Applicable Instrumentation & Controls Design Drawings.Initially Reported on 841219.Checklists Will Be Used During Verification of Drawing Rev Process ML20107H9371985-02-14014 February 1985 Final Deficiency Rept,Item 145 Re Tubing Configuration & Connection Hook Up Discrepancy.Initially Reported on 850115. Solenoid Valves on Nitrogen Inerting/Purge Makeup Sys Reinstalled.Operation Will Be Verified ML20107F1181985-02-12012 February 1985 Final Deficiency Rept,Item 146 Re Failure of Colt Industries Emergency Diesel Generators 11 & 12.Initially Reported on 850118.Procedures Revised to Require 2-minute Prelubrication Prior to Generator Starts ML20106B5021985-02-0101 February 1985 Final Deficiency Rept,Item 142 Re Failure of Two Target Rock Solenoid Valves.Initially Reported on 841213.Engineering Design Package & Field Mod Request Issued to Change Field Wiring ML20101U0751985-01-18018 January 1985 Interim Deficiency Rept,Item 143 Re Deviations Between Design Documents & as-built Plant.Initially Reported on 841218.Evaluation of as-built Drawings to Define Scope of Problem Performed ML20101U0591985-01-15015 January 1985 Amended Deficiency Rept,Item 111 Re Design Defect on RHR Reservoir Freeze Over.Temporary Auxiliary Boiler Will Be Used to Add Heat to RHR Svc Water Reservoirs,Instead of Operating Emergency Diesel Generators ML20114D2251985-01-11011 January 1985 Interim Deficiency Rept,Item 142 Re Failure of Two Target Rock Solenoid Valves.Initially Reported on 841213. Investigation of Cause,Scope & Necessary Corrective Action for Problem Continuing ML20101P2771984-12-18018 December 1984 Final Deficiency Rept,Item 141 Re Deviations from Specified Clearance Between Cable Trays & Vertical Support Members. Initially Reported on 841107.Item Not Reportable Per 10CFR50.55(e) ML20101M9621984-12-13013 December 1984 Amend to Final Deficiency Rept,Item 114 Re Possible Overpressurization of North RHR Hx.Initially Reported on 840124.Investigation & Analysis Determined HX Acceptable for Intended Function ML20101M9521984-12-12012 December 1984 Final Deficiency Rept,Item 139 Re Deficient Shop Weld in Fluid Head Structure.Initially Reported on 841015.Review of Stress Calculations Revealed Max Stress on Welds Does Not Exceed Allowable.Item Not Reportable Per 10CFR50.55(e) ML20100N8841984-11-30030 November 1984 Supplemental Final Deficiency Rept,Item 111 Re Design Deficiency on RHR Reservoir Freeze Over.Methods for Adding Heat to RHR Reservoir Clarified ML20100N8651984-11-30030 November 1984 Amended Final Deficiency Rept,Item 116 Re Potential Design Deficiency Allowing Freezing of Buried Piping Sys.Walls Will Be Installed & Temp Monitored.Pipes Will Not Be Rerouted ML20100L2041984-11-30030 November 1984 Interim Deficiency Rept,Item 141 Re Deviations from Specified Clearance Between Cable Trays & Vertical Support Members.Initially Reported on 841107.As-built Tray/Hanger Clearance for Hangers & Cable Trays Acceptable ML20100K7301984-11-27027 November 1984 Final Deficiency Rept,Item 129 Re Lack of Design Calculations for HVAC Duct Supports.Initially Reported on 840614.Supports & Base Plates Modified & Installation Discrepancies Documented on Nonconformance Repts ML20099F5011984-11-0505 November 1984 Final Deficiency Rept,Item 121 Re Water Found in HPCI Lube Oil Reservoir.Initially Reported on 840330.Byron-Jackson Field Mod Request 6337 Revised to Provide Proper Piping Configuration for Main Pump Seal ML20099E3911984-11-0303 November 1984 Final Amended Deficiency Rept,Item 76 Re Limitorque Switch Rotor Failures.Initially Reported on 820731.Repairs Performed Per Maint Instructions MI-M070,M179,M182,M203,M272 & M187 ML20099F5381984-11-0202 November 1984 Final Part 21/deficiency Rept Re Contaminated Hydraulic Fluid in Hydraulic Pipe Snubbers.Initially Reported on 821015.All Affected Hydraulic Pipe Snubbers Returned to Power Piping Co for Refurbishment ML20099F5261984-10-31031 October 1984 Final Deficiency Rept,Item 112 Re Poor Quality of Vendor Connection Workmanship in Emergency Diesel Generator Panels. Initially Reported on 840113.Deficient Wiring Terminations Documented on Nonconformance Repts Reterminated 1997-09-30
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML20217N4381999-10-25025 October 1999 Safety Evaluation Supporting Amend 17 to License DPR-9 ML20217P3551999-10-22022 October 1999 LER 99-S01-00:on 990922,loaded 9mm Handgun Was Discovered on Truck Cargo Area of Vehicle Inside Protected Area.Caused by Inadequate Vehicle Search.Guidance in Procedures & Security Training to Address Multiple Vehicle Searches Was Provided NRC-99-0095, Monthly Operating Rept for Sept 1999 for Fermi 2.With1999-09-30030 September 1999 Monthly Operating Rept for Sept 1999 for Fermi 2.With NRC-99-0067, Monthly Operating Rept for Aug 1999 for Fermi 2.With1999-08-31031 August 1999 Monthly Operating Rept for Aug 1999 for Fermi 2.With NRC-99-0065, Monthly Operating Rept for July 1999 for Fermi 2.With1999-07-31031 July 1999 Monthly Operating Rept for July 1999 for Fermi 2.With NRC-99-0088, Detroit Edison Co Enrico Fermi Atomic Power Plant,Unit 1 Annual Rept for Period 980701-990630. with1999-06-30030 June 1999 Detroit Edison Co Enrico Fermi Atomic Power Plant,Unit 1 Annual Rept for Period 980701-990630. with NRC-99-0064, Monthly Operating Rept for June 1999 for Fermi 2.With1999-06-30030 June 1999 Monthly Operating Rept for June 1999 for Fermi 2.With NRC-99-0062, Monthly Operating Rept for May 1999 for Fermi 2.With1999-05-31031 May 1999 Monthly Operating Rept for May 1999 for Fermi 2.With ML20206J9301999-05-10010 May 1999 SER Concluding That Util Adequately Addressed Actions Requested in GL 95-07, Pressure Locking & Thermal Binding of Safety-Related Powered-Operated Gate Valves ML20206G5081999-05-0505 May 1999 Safety Evaluation Approving Request for Relief PR-8,Rev 2 on Basis That Licensee Committed to Meet All Related Requirements of ASME OM-6 Std & PR-12 on Basis That Proposed Alternative Will Provide Acceptable Level of Safety NRC-99-0022, Monthly Operating Rept for Apr 1999 for Fermi 2.With1999-04-30030 April 1999 Monthly Operating Rept for Apr 1999 for Fermi 2.With ML20205Q7141999-04-15015 April 1999 Safety Evaluation Supporting Amend 16 to License DPR-9 ML20205P9721999-03-31031 March 1999 Monthly Operating Rept for Mar 1999 for Fermi 2 ML20204E0371999-03-17017 March 1999 Safety Evaluation Accepting Licensee Request for NRC Approval of Alternative Rv Weld Exam,Per Provisions of 10CFR50.55a(a)(3)(i) & 10CFR50.55a(g)(6)(ii)(A)(5) for Plant,Unit 2 for 40-month Period ML20204D0361999-02-28028 February 1999 Monthly Operating Rept for Feb 1999 for Fermi 2 ML20198S3341999-01-0606 January 1999 Safety Evaluation Supporting Amend 15 to License DPR-9 NRC-99-0005, Monthly Operating Rept for Dec 1998 for Fermi 2.With1998-12-31031 December 1998 Monthly Operating Rept for Dec 1998 for Fermi 2.With ML20207B7491998-12-31031 December 1998 1998 Annual Operating Rept for Fermi 2 ML20205Q9621998-12-31031 December 1998 Revised Monthly Operating Rept for Dec 1998 for Fermi 2 NRC-99-0021, 1998 Annual Financial Rept for Detroit Edison Co. with1998-12-31031 December 1998 1998 Annual Financial Rept for Detroit Edison Co. with NRC-98-0153, Monthly Operating Rept for Nov 1998 for Fermi 2.With1998-11-30030 November 1998 Monthly Operating Rept for Nov 1998 for Fermi 2.With NRC-98-0160, Monthly Operating Rept for Oct 1998 for Fermi 2.With1998-10-31031 October 1998 Monthly Operating Rept for Oct 1998 for Fermi 2.With ML20154R2331998-10-21021 October 1998 Safety Evaluation Supporting Amend 13 to License DPR-9 ML20154L1031998-10-14014 October 1998 Safety Evaluation Accepting Licensee Response to NRC Bulletin 95-002, Unexpected Clogging of Residual Heat Removal Pump Strainer While Operating in Suppression Pool Cooling Mode NRC-98-0139, Monthly Operating Rept for Sept 1998 for Fermi,Unit 2.With1998-09-30030 September 1998 Monthly Operating Rept for Sept 1998 for Fermi,Unit 2.With ML20154H8161998-09-30030 September 1998 Rev 0 to COLR Cycle 7 for Fermi 2 ML20153B8811998-09-18018 September 1998 Safety Evaluation Accepting Request for Relief from Certain Requirements of ASME Boiler & Pressure Vessel Code,Section Xi,For Plant,Unit 2 ML20151X0651998-09-11011 September 1998 Safety Evaluation Re Inservice Testing Program Relief Request VR-63 for Plant NRC-98-0111, Monthly Operating Rept for Aug 1998 for Fermi 2.With1998-08-31031 August 1998 Monthly Operating Rept for Aug 1998 for Fermi 2.With ML20153B7921998-08-31031 August 1998 Rev 0 to Fermi 1 Sar ML20237E1171998-08-25025 August 1998 Safety Evaluation Accepting Licensee Relief Requests for First 10-yr Interval Inservice Insp Nondestructive Exam Program ML20236X8611998-08-0505 August 1998 SER Related to Revised Feedwater Nozzle Analysis to Facility Operating License NPF-43,Enrico Fermi Nuclear Power Plant, Unit 2 NRC-98-0109, Monthly Operating Rept for July 1998 for Fermi 21998-07-31031 July 1998 Monthly Operating Rept for July 1998 for Fermi 2 ML20236K3261998-07-0101 July 1998 SER Accepting Licensee Response Related to Revised Feedwater Nozzle Analysis to License NPF-43 for Enrico Fermi Nuclear Power Plant,Unit 2 NRC-98-0097, Monthly Operating Rept for June 1998 for Fermi,Unit 21998-06-30030 June 1998 Monthly Operating Rept for June 1998 for Fermi,Unit 2 NRC-98-0127, Annual Rept for Period 970701-9806301998-06-30030 June 1998 Annual Rept for Period 970701-980630 NRC-98-0079, Monthly Operating Rept for May 1998 for Fermi 21998-05-31031 May 1998 Monthly Operating Rept for May 1998 for Fermi 2 NRC-98-0076, Monthly Operating Rept for Apr 1998 for Fermi 21998-04-30030 April 1998 Monthly Operating Rept for Apr 1998 for Fermi 2 NRC-98-0072, Monthly Operating Rept for Mar 1998 for Fermi 21998-03-31031 March 1998 Monthly Operating Rept for Mar 1998 for Fermi 2 NRC-98-0050, Monthly Operating Rept for Feb 1998 for Fermi 21998-02-28028 February 1998 Monthly Operating Rept for Feb 1998 for Fermi 2 NRC-98-0019, Monthly Operating Rept for Jan 1998 for Fermi 21998-01-31031 January 1998 Monthly Operating Rept for Jan 1998 for Fermi 2 ML20198L4241998-01-0808 January 1998 Safety Evaluation Accepting Proposed Rev 2 to Relief Request VR-51 Under Fermi 2 Pump & Valve Inservice Testing Program Per 10CFR50.55a(f)(6)(i) for First 10-yr Interval NRC-98-0015, Monthly Operating Rept for Dec 1997 for Fermi 21997-12-31031 December 1997 Monthly Operating Rept for Dec 1997 for Fermi 2 ML20217N3821997-12-31031 December 1997 Annual Operating Rept for 970101-1231 NRC-98-0053, 1997 Annual Financial Rept for Detroit Edison Company1997-12-31031 December 1997 1997 Annual Financial Rept for Detroit Edison Company ML20205Q9601997-12-31031 December 1997 Revised Monthly Operating Rept for Dec 1997 for Fermi 2 NRC-97-0141, Deficiency Rept Re Malfunction of EDG Number 11 Automatic Voltage Regulator (AVR) Printed Circuit Board Rev B,Due to Failure of Operational Amplifier U8 Chip.Avr Board Rev B Was Sent Offsite to Independent Engineering Facility1997-12-23023 December 1997 Deficiency Rept Re Malfunction of EDG Number 11 Automatic Voltage Regulator (AVR) Printed Circuit Board Rev B,Due to Failure of Operational Amplifier U8 Chip.Avr Board Rev B Was Sent Offsite to Independent Engineering Facility ML20197A9921997-12-15015 December 1997 Rev 0 to Efp,Unit 1 Fermi 1 Sar NRC-97-0131, Monthly Operating Rept for Nov 1997 for Fermi 21997-11-30030 November 1997 Monthly Operating Rept for Nov 1997 for Fermi 2 ML20248H1151997-10-31031 October 1997 Rev 1 to Colr,Cycle 6 for Fermi 2 1999-09-30
[Table view] |
Text
- . .
kk DEFICIENCY REPORT
'
TORUS SHELL INDICATIONS AT THE RING BEAM ATTACHMENT WELD ENLARGEMENT INTRODUCTION The primary containment for the Enrico Fermi Atcmic Power Plant, Unit 2 was designed, erected, leak tested and N-stamped in accordance with the ASPE Boiler and Pressure Vessel Code during the early 1970's. Subsequently, new torus hydrodynamic loads were identified. The new loads were related to pool response due to postulated LOCA and pool response due to main steam relief valve operation. Detroit Edison has committed to a torus modifica-tion program that would provide design, analysis and implementation of modi-fications so that the modified torus structure will withstand these new loads and comply with the acceptable design margins. A detailed description of the torus modification program and the required modifications was submitted to NRC via Amendment No. 12 of the FSAR, Section 3.8.2 and Reference 17.
The installation of the designed modifications is being performed by Reactor Controls Inc. As part of the modification program, the existing 5/16" fillet weld between the ring girder at each mitered joint and the suppres-sion chamber shell is being increased to 3/4" fillets as shown in Figure 1.
In the process of inspecting these welds, defects in the toe of the welds were discovered. The typical locations of these defects are illustrated in Detail A of Figure 1.
Description of the Defects The indications were discovered to be relevant defects through magnetic particle examination and liquid penetrant examination. The de fects pre-dominantly are oriented parallel to the welds in the area shown in Figure 1.
Presently, ultrasonic examination is being conducted to determine the presence of subsurface indications. Documentation providing dimensional description and location of the defects is available at the site.
Failure Analvsis Ten (10) metal samples were removed from selected locations of the torus ring beam welds to determine the cause of the cracking. Metallurgical and fractographic methods were used to examine these samples. Hardness tra-verses and chemical analyses were also performed. The surface cracks were found to emanate from the toe of the outermost veld pass of the 3/4" weld.
The subsurface cracks observed in the samples emanated from the underbead 7905090355
.
Failure Analysis (contd) welds and were determined to have initiated while applying the 3/4" weld.
The cracks then ran through the heat affected zone (HAZ) downward into the shell base material. Once the cracks were in the base material of the shell, they propagated along and across the banded microstructure in a stepwise fashion.
The base material chemical analysis and hardness were typical for SA516, Grade
- 70. Hardness in the HAZ of most of the samples examined exceed 400 Knoop.
A complete metallurgical report is on file at the site.
Cause of Cracking The cracks were found to be a result of hydrogen cracking and were charac-terized by intergranular fracture of coarse grained HAZ. The RAZ of welds which exhibited cracking were excessively hard (Knoop 400). The high hard-ness HAZ's resulted from rapid cooling and lead to the subsequent formation of martensite, which is susceptible to hydrogen cracking.
Corrective Action After the defects were discovered, a Repair Program Document was written and submitted to the State of Michigan for the repair, as required by the ASME Code. The corrective action consisted of physically removing, by grind-ing of all relevant surface and subsurface indications. The base metal and 3/4" fillet welds were restored by utilizing new welding procedures that speci-fied electrode baking (6000 to 800 F), preheat (300 to 4000F), specific minicum energy input, and post-weld baking temperature and duration.
The weld repaired area will be magnetic particle examined and ultrasonic test-ed after a minimum of at least 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after the post bake duration is com-pleted and the weld metal returned to ambient temperature. An integrated leak rate test of the containment vessel in accordance with Appendix J of 10CFR50 will be performed prior to start-up.
Design Acceptance Criteria / Code The primary containment was originally designed, erected, leak tested and N-stamped in conformance with the 1968 Edition (through summer 1969 Addenda) of section III of the ASME Boiler and Pressure Vessel Code.
For the design and analysis conducted for the containment modification pro-gram, the design rules and stress limits of the 1977 Edition (through summer 1977 Addenda) of the ASME section III code are used. In utilizing the ASME Code, the suppression chamber and vent system are classified as class MC components and therefore, the rules of subsection NE are applied.
Safety Imolication of the Deficiencv A preliminary fracture mechanics analysis indicated that the nature of cracks existing in the toe of the weld would most probably not be tolerated in view of the cyclic nature of some of the hydrodynamic loads. The indications were de-tected and repaired as part of the normal site inspection program. The repaired structure will perform its safety function as designed.
P
.
. FIGURE 2
.
.
. l
[
( \
~
\
g
'
-MITRE JOINT i
,-, E- < J ,,,1c a E,cc , _
SEE DETAIL A
.
6 RING GIRDER
~t~
~%_ ~
/ \
\ \
t
.u- x '
.
}
attNroacED RCI h' ELD TYPICAL DEFECT EXISTING REGION
-
CBI hTLD
,$- ,
< jfl --- >
' DETAIL A ,
.
T F OR A4@1 eena m - - - - - ,
_--.n_"~~~~ ',
t 1, -
. .
~
k.