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| | RosenT E. DenTox Baltimore Gas and Electric Company Vice President Calvert Cliffs Nuclear Power Plant Nuclear Energy 1650 Calven Cliffs Parkway Lusby, Maryland 20657 410 586-2200 Eri.4455 loca; 4t0 260-4455 Baltimore January 10,1995 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION: Document Control Desk |
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| | ==SUBJECT:== |
| | Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 10 CFR Part 21 Report; Non-Conservative Modeling of Reactor Coolant System Sensible IIeat For Containment Pressure Resnonse Safety Analysis During a review of our Updated Final Safety Analysis Report Safety Analysis concerning containment pressure response, we determined the Bechtel analysis of the long-term cooling phase of a loss of coolant accident did not model heat transfer from Reactor Coolant System (RCS) metal components to the RCS coolant. This omission potentially results in a non-conservative calculated containment temperature during l a specific time period of the analysis (after containment peak temperature until several days after the l cvent). Although we have concluded this non-conservative assumption has no safety significance for Calvert Cliffs, we are reporting it under Part 21 because this problem may potentially represent a safety consequence to other licensees who use similar methodologies. |
| | 1 Bechtel has informed us that they are evaluating the generic implications, if any, of this modeling omission and will report the results of their evaluation to us. |
| | A verbal notification and written summary were submitted to the Nuclear Regulatory Commission Operations Center via facsimile on December 9,1994. |
| | Should you have any questions regarding this matter, we will be pleased to discuss them with you. |
| | Very truly yours, es |
| | - 3 RED /CDS/bjd Attachment |
| | ~ 9501130161 950110 l ! |
| | '@ ADOCK 05000317 |
| | .PDR |
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| | _%-t Control Desk January 10,1995 Page 2 cc: D. A. Brune, Esquire , |
| | J. E. Silberg, Esquire L. B. Marsh, NRC D. G. Mcdonald, Jr.,'NRC T. T. Martin, NRC P. R. Wilson, NRC R. I. McLean, DNR J. H. Walter, PSC t |
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| | . 10 CFR PART 21 REPORT; NON-CONSERVATIVE MODELING OF RCS SENSIBLE HEAT FOR CONTAINMENT PRESSURE RESPONSE SAFETY ANALYSIS COULD RESULT IN A SLIGHT INCREASE IN POST-ACCIDENT CONTAINMENT TEMPERATURE Calvert Cliffs Nuclear Power Plant, Units I and 2 Docket Nos. 50-317 and 50-318 1 |
| | (i) Name and address ofindividual making notification: |
| | R. E. Denton, Vice President, Nuclear Energy Baltimore Gas and Electric Company , |
| | Calvert Cliffs Nuclear Power Plant l 1650 Calvert Cliffs Parkway Lusby, MD 20657-4702 l |
| | (ii) Basic Component Affected: l l |
| | Updated Final Safety Analysis Report Chapter 14.20, " Containment Pressure Response." |
| | Specifically the long-term cooling phase modeled by Bechtel's Containment Pressure and Temperature Transient Analysis (COPATTA) Code. ; |
| | (iii) Firms Supplying Component: ! |
| | Bechtel Power Corporation (iv) Nature of Defect: |
| | Chapter 14.20 of our Updated Final Safety Analysis Report (UFSAR), " Containment Pressure Response," is an analysis of the pressure and temperature response of our containments to design basis accidents such as a main steam line break or a loss of coolant accident (LOCA). A spectrum of Reactor Coolant System (RCS) break sizes were considered to determine the worst condition of RCS mass and energy releases in combination with sensible and shutdown heat sources during the blowdown phase of a LOCA. The containment response to these breaks was analyzed assuming various limiting single failures. |
| | The RCS blowdown transient results in primary containment pressure and temperature peaks as a result of the mass and energy transferred from the reactor core to the primary coolant and to the containment atmosphere. During the refill and reflood phases of the accident scenario, heat in the steam generator water mass is transferred to the primary coolant via a reverse heat flow and then into the containment atmosphere. In addition, safety injection water reflooding into an uncovered core and ti.e hot RCS system picks up heat from those sources and deposits it into the Containment as saturated or even superheated steam. |
| | The mass and energy transfer from the RCS for various phases of the accident are calculated by Combustion Engineering (CE) and Bechtcl. The blowdown phase of the LOCA is modeled using the CE FLASil code, the refill and reflood phases by the CE FLOOD code, and the long-term 1 |
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| | . 10 C7R PART 21 REPORT; NON-CONSERVATIVE MODELING OF RCS SENSIBLE HEAT FOR CONTAINMENT PRESSURE RESPONSE SAFETY ANALYSIS COULD RESULT IN A SLIGHT INCREASE IN POST-ACCIDENT l CONTAINMENT TEMPERATURE cooling phase by Bechtel. The mass and energy transfer data is input to Bechtel's Containment Pressure and Temperature Transient Analysis (COPATTA) code for calculation of contaimnent pressure and temperature. During the long-term cooling phase (after reflood) the transfer of sensible heat from the RCS metal back into the coolant is not modeled. When RCS metal sensible heat is included, the result is a higher enthalpy coolant flowing from the RCS break into Containment. He higher enthalpy coolant flowing into the containment leads to slightly higher containment temperatures and pressures for several days after their peaks. Preliminary analysis indicates the problem has no effect on containment peak pressure or peak temperature. We have concluded that there are no adverse effects to our environmental qualification program. |
| | (v) Date on Which Defect Was Identified: |
| | He problem was identified by BGE during a review of the UFSAR Chapter 14.20 Safety Analysis, and documented on an Issue Report on November 9,1994. |
| | (vi) Number and Location of Components: |
| | Not applicable. |
| | (vii) Corrective Actions Taken: |
| | We have asked CE to provide new mass and energy transfer data that accounts for sensible heat transfer from the RCS metal to the coolant. The revised data produced by CE will be provided to Bechtel to produce revised containment pressure and temperature response curves. He results of the revised containment response curves are expected to show: |
| | A. Containment primary peak pressure and temperature will be unaffected, l |
| | B. The intermediate containment temperature will be increased by less than 2'F. |
| | 1 C. He containment temperature and pressure will be essentially unaffected beginning several days after the start of the event. , |
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| | %c results of this reanalysis are being evaluated for impact on other aspects of our current Ocensing basis. The most significant potential impact was the increased load on our SRW system l via the containment air coolers. We have no current operability concerns due to low ultimate heat l sink temperatures at the present time and expect that the final reanalysis will show the real effect ! |
| | on our current safety analysis margins will be minimal. |
| | Bechtel has informed us that they are evaluating the generic implications, if any, of this modeling omission and will report the results of their evaluation by January 20,1995. |
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Category:DEFICIENCY REPORTS (PER 10CFR50.55E & PART 21)
MONTHYEARLD-99-039, Part 21 Rept Re Defect of Abb 1200A 4kV Vacuum Breakers. Initially Reported on 990625.Defect Results in Breaker Failing to Remain in Closed Position.Root Cause Evaluation & Corrective Action Plan Being Developed.Licensee Notified1999-06-30030 June 1999 Part 21 Rept Re Defect of Abb 1200A 4kV Vacuum Breakers. Initially Reported on 990625.Defect Results in Breaker Failing to Remain in Closed Position.Root Cause Evaluation & Corrective Action Plan Being Developed.Licensee Notified LD-99-035, Part 21 Rept Re Abb 1200A 4KV Vacuum Breakers Performing Trip Free Operation When Close Signal Received by Breaker. Defect Results in Breaker Failing to Remain in Closed Position.Root Cause & CAP Being Developed1999-06-25025 June 1999 Part 21 Rept Re Abb 1200A 4KV Vacuum Breakers Performing Trip Free Operation When Close Signal Received by Breaker. Defect Results in Breaker Failing to Remain in Closed Position.Root Cause & CAP Being Developed ML20153C1091998-09-18018 September 1998 Part 21 Rept Re Defective Capacity Control Valves.Trentec Personnel Have Been in Contact with Bg&E Personnel Re Condition & Have Requested Potentially Defective Valves ML18066A2771998-08-13013 August 1998 Part 21 Rept Re Deficiency in CE Current Screening Methodology for Determining Limiting Fuel Assembly for Detailed PWR thermal-hydraulic Sa.Evaluations Were Performed for Affected Plants to Determine Effect of Deficiency ML20217J9811998-04-28028 April 1998 Part 21 Rept Re Incorrect Description of Drift Specification for Model 1154,gauge Pressure Transmitters,Range Code 0 in Manual Man 4514,Dec 1992.Cause Indeterminate.Will Issue & Include Errata Sheets in All Future Shipments to Users 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 ML17309A6211997-09-29029 September 1997 Part 21 Rept Re Final Disposition of Masterflow 713 & Embeco 636 Grout Nonconformance Reported by Master Builders,Inc. Licensee Continuing to Monitor shelf-life of Masterflow 713 & Embeco 636 Grouts Produced at Rancho Cucamonga LD-97-024, Part 21 Rept Re Error in Energy Redistribution Factor Used in LOCA Analysis for Listed Plants for Which ABB-CE Performed Analysis.Issued Recommendations Info Bulletin 97-0041997-08-14014 August 1997 Part 21 Rept Re Error in Energy Redistribution Factor Used in LOCA Analysis for Listed Plants for Which ABB-CE Performed Analysis.Issued Recommendations Info Bulletin 97-004 ML20149J8681997-07-22022 July 1997 Part 21 Rept Re Failure of Main Steam Header Radiation Monitors Supplied by Nuclear Research Corp.Caused by Defect in Installed Basic Component.Declared Monitors Inoperable & Implemented Alternate Preplanned Monitoring Method ML20149D3121997-07-14014 July 1997 Part 21 Draft Rept Re 970606 Failure of Main Steam Header Radiation Monitors Supplied by Nuclear Research Corp.Caused by Temperature Compensation.Detectors Declared Inoperable & Removed for Repair LD-97-002, Part 21 Rept Re Piping Line Loss Between SG & MSIV Inlet When MSSVs Area Activated.Recommends That Utils Confirm Proper Adjustment of MSSV Blowdown Settings So as to Preclude Valve Chatter & Related Structural Concerns1997-01-17017 January 1997 Part 21 Rept Re Piping Line Loss Between SG & MSIV Inlet When MSSVs Area Activated.Recommends That Utils Confirm Proper Adjustment of MSSV Blowdown Settings So as to Preclude Valve Chatter & Related Structural Concerns ML20133M2501997-01-15015 January 1997 Part 21 Rept Re Failures of GE Type AMH-4.76-250 Circuit Breakers.Caused by Bent Trip Lever.Replaced Trip Paddles, Support Bracket & Spring Discharge Link ML20133E8001997-01-0808 January 1997 Deficiency Rept Re Nonconformance Related to Masterflow 713 Grout,Which Master Builders,Inc Has Supplied as Nuclear SR Product to 18 Npps.Cause Unknown.Requests That Listed Info Be Provided to Gain Insight as to Scope & Possible Cause ML20134E8171996-10-25025 October 1996 Part 21 Rept Re Bent Manual Trip Paddles in GE Magne Blast 4-kV Circuit Breakers.Investigation Revealed No Gap Between Manual Trip Rod & Manual Trip Lever.Definitive Explanation for Breaker Failures Not Been Confirmed ML18065B0111996-10-18018 October 1996 Part 21 Rept Re Application of Certain Aspects of ABB-CE Safety Analysis Methodology ML20115J3981996-07-22022 July 1996 Interim Part 21 Rept Re 3/4 Schedule 80 Pipe Furnished to Consolidated Power Supply.Investigation Revealed Only One Nuclear Customer Involved in Sale of Matl ML20112G9811996-05-29029 May 1996 Part 21 Rept Re Bechtel Job 21464 Calvert Cliffs Nuclear Power Plant DG Project.Plant Start Up Problem Rept 96-06M Addressed Oil Filter O-Rings,filter Element & Filter Holder ML20101L2051996-03-28028 March 1996 Followup to Part 21 Rept Re Failures of gould-shawmut Fuses. Initial Investigation Into Issue Revealed Certain Percentage of Fuses Developed Cracks in Fuse Elements ML20091P4271995-08-24024 August 1995 Final Part 21 Rept Re Regular Locknut Being Installed on Governor Where Thinner Locknut Required at Calvert Cliffs. Applications of Thick Nut P/N 75233A06 on Control Linkages Will Be Reviewed to Insure Applications Correct ML20083L0411995-05-0505 May 1995 Interim Part 21 Rept Re Failures of Gould-Shawmit A25X 10-15 Ampere Fuses Due to Cracking of Fuse Element.Util Not Yet Verified That Mfg Process Described Cause of Failures & Performing Own Metallurgical Analysis on Fuses ML20077M7581995-01-10010 January 1995 Part 21 Rept,Determined That Bechtel Power Corp Analysis of long-term Cooling Phase of LOCA Did Not Model Heat Transfer from RCS Metal Components to RCS Coolant.Util Asked C-E to Provide New Mass & Energy Transfer Data ML20078R2721994-12-14014 December 1994 Part 21 Rept Re Auxiliary Feedwater Pump Turbine Governor Valve Binding.Caused by Galvanic & Crevice Corrosion Between Stem & Stem Packing Components.Licensees Replaced Stem & Packing Gland Matls ML20078Q1641994-12-0909 December 1994 Part 21 Rept Re Result in Slight Increase in post-accident Containment Temp.Licensees Have No Current Operability Concerns Due to Low Ultimate Heat Sink Temps at Present Time ML20080A7681994-11-15015 November 1994 Part 21 Rept Re AFW Pump Turbine Governor Valve Binding Caused by Galvanic & Crevice Corrosion Between Stem & Stem Packaging Components.Turbine Mfg by Terry Steam Turbine Co. Licensee Plans to Periodically Exercise Valve Stems ML20070K8111994-07-20020 July 1994 Interim Part 21 Rept Re OP 38TD8-1/8 CS Injection Pump Erosion Sleeve Cavitation,Reported by Bg&E.Vendor Pursuing Evaluation to Determine Whether Situation Could Potentially Affect All Nuclear Utils Who Operate Subj Sleeve ML20070M6451994-04-26026 April 1994 Part 21 Rept Re anti-rotation Keys for 6-inch MOVs Mfg by Velan.New Keys Machined on-site to Dimensional Requirements of New Drawings Supplied by Vendor Installed & Performed Satisfactorily 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 LD-93-019, Part 21 Rept Re Defect in Input to Better Axial Shape Selection Sys (Basss) Computer Code.Caused by Inconsistency Between Basss User Documentation & Code.Initially Determined on 930205.Correct Input Provided1993-02-12012 February 1993 Part 21 Rept Re Defect in Input to Better Axial Shape Selection Sys (Basss) Computer Code.Caused by Inconsistency Between Basss User Documentation & Code.Initially Determined on 930205.Correct Input Provided ML20126J5961992-12-31031 December 1992 Part 21 Rept Re Potential Loss of RHR Cooling During Nozzle Dam Removal.Nozzle Dams May Create Trapped Air Column Behind Cold Leg Nozzle Dam.Mod to Nozzle Dams Currently Underway. Ltrs to Affected Utils Encl ML20125C7161992-12-0707 December 1992 Part 21 Rept Re Possibility for Malfunction of Declutching Mechanisms in SMB/SB-000 & SMB/SB/SBD-00 Actuators. Malfunction Only Occurs During Seismic Event.Balanced Levers May Be Purchased from Vendor.List of Affected Utils Encl ML20127P5861992-11-23023 November 1992 Followup to 921005 Part 21 Rept Re Potential Defect in SB/SBD-1 Housing Cover Screws.Procedure Re Replacement of SBD-1 Spring Cover Bolts Encl.All Fasteners Should Be Loosened & Removed.List of Affected Utils Encl ML20077N5061991-08-0909 August 1991 Part 21 Rept Re Defective 3/8 inch,3-way Solenoid Valve Model Supplied by Automatic Switch Co.Cv Valves Will Be Specified on Future Purchase Order W/Actual Test Values Requested for Each Valve L-91-002, Supplemental Part 21 Rept Re GE Reactor Trip Breakers Used in safety-grade Equipment.Initially Reported on 901228.List of Plants Supplied w/C-E Breakers Encl1991-01-0404 January 1991 Supplemental Part 21 Rept Re GE Reactor Trip Breakers Used in safety-grade Equipment.Initially Reported on 901228.List of Plants Supplied w/C-E Breakers 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 ML20056A4151990-08-0303 August 1990 Part 21 Rept Re Thomas & Betts Electrical Terminal Lug Cracking Around Barrel.Initially Reported on 900731.All Thomas & Betts Products Currently Stocked in Warehouses Isolated & Ordered Held in Warehouse ML20012C1051990-03-0707 March 1990 Part 21 Rept Re Several Failures of Fairbanks Morse Engine Div Piston Pins/Bushings on Upper Pistons.Caused by Incorrect Surface Pattern on Piston Pins.Piston Pins Under Listed Purchase Orders to Be Removed & Replaced ML20005G6831990-01-0505 January 1990 Part 21 Rept Re Installation Instructions for Grommet Use Range for Patel Conduit Seal P/N 841206.Conduit Seals in Environ Qualification Applications Inspected for Proper Wire Use Range & Grommets Replaced ML20246M7461989-07-13013 July 1989 Part 21 Rept Re Steam Generator Snubber Nuts Found Not to Meet Mfg Matl Composition Specs.Initially Reported on 890712.All 150 Nuts Will Be Replaced w/A194Gr2H Nuts ML20244D4091989-06-0606 June 1989 Corrected Part 21 Rept Re Responsible Officers for Reporting of Defects & Noncompliance.One of Creel Alternates Listed in Error in .Alternate Should Read as Stated ML20236C2721989-03-15015 March 1989 Part 21 Rept Re Nuclear fuel-potential Loss of Shutdown margin.C-E Issuing Info Bulletin Re Shutdown Margin During Refueling ML20236A9391989-03-0707 March 1989 Part 21 Rept Re Emergency Diesel Generator Fuel Supply Crossover Line Mfg by Fairbanks Morse.Initially Reported on 890303.Fuel Leaking from Line Could Come in Contact W/Hot Engine Parts.Crossover Pipe Will Be Replaced ML20207K7831988-09-29029 September 1988 Part 21 Rept Re Defect in Amphenol SAMS Model 205-0034 Electrical Penetration Assembly.Metallurgical Analysis Revealed That Studs Made of Copper Alloy & Alloy Has Degraded.Equipment Replaced on Unit 1 ML20155C3681988-09-20020 September 1988 Part 21 Rept Re Deviation in Westinghouse Type Ds 206 & 416 Circuit Breakers.Crimp Connections Repaired 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 ML20214E6241987-05-0707 May 1987 Part 21 Rept Re Design of Extension Bonnets Supplied in 1980 for Four Pressurizer Spray Valves.Thielsch Engineering Assoc Retained to Inspect & Make NDE of Welds 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 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 ML20126C6901985-06-0505 June 1985 Part 21 Rept Re Generator Failure.Concurs W/Encl Louis Allis That Interpolar Connectors Be Removed 1999-06-30
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML20217G6971999-09-30030 September 1999 Monthly Operating Repts for Sept 1999 for Calvert Cliffs Npp,Units 1 & 2.With ML20216J8731999-09-10010 September 1999 Rev 52 to QA Policy for Calvert Cliffs Nuclear Power Plant ML20212A4441999-08-31031 August 1999 Monthly Operating Repts for Aug 1999 for Ccnpp,Units 1 & 2. with ML17326A2011999-08-23023 August 1999 LER 99-004-00:on 990724,reactor Tripped Due to Main Transformer Bushing Flashover.Plant Was Brought to SS & Components Were Tested & Performed Satisfactorily.With 990823 Ltr ML20210S6091999-07-31031 July 1999 Monthly Operating Repts for July 1999 for Ccnpp,Units 1 & 2. with ML20210N6001999-07-27027 July 1999 ISI Summary Rept for Calvert Cliffs Unit 2. Page 2 of 3 in Encl 1 of Incoming Submittal Not Included ML20210B7941999-07-15015 July 1999 SER Denying Licensee Request for Changes to Current Ts,Re Deletion of Tendon Surveillance Requirements for Calvert Cliffs LD-99-039, Part 21 Rept Re Defect of Abb 1200A 4kV Vacuum Breakers. Initially Reported on 990625.Defect Results in Breaker Failing to Remain in Closed Position.Root Cause Evaluation & Corrective Action Plan Being Developed.Licensee Notified1999-06-30030 June 1999 Part 21 Rept Re Defect of Abb 1200A 4kV Vacuum Breakers. Initially Reported on 990625.Defect Results in Breaker Failing to Remain in Closed Position.Root Cause Evaluation & Corrective Action Plan Being Developed.Licensee Notified ML20209F1721999-06-30030 June 1999 Monthly Operating Repts for June 1999 for Calvert Cliffs Npp.With LD-99-035, Part 21 Rept Re Abb 1200A 4KV Vacuum Breakers Performing Trip Free Operation When Close Signal Received by Breaker. Defect Results in Breaker Failing to Remain in Closed Position.Root Cause & CAP Being Developed1999-06-25025 June 1999 Part 21 Rept Re Abb 1200A 4KV Vacuum Breakers Performing Trip Free Operation When Close Signal Received by Breaker. Defect Results in Breaker Failing to Remain in Closed Position.Root Cause & CAP Being Developed ML20196C6981999-06-21021 June 1999 Safety Evaluation Concluding That Use of ASME Section XI Code Including Summer 1983 Addenda as Interim Code for Third 10-year Insp Interval at Calvert Cliffs Units 1 & 2 Until Review of 1998 Code Completed,Would Be Acceptable ML20195K2811999-05-31031 May 1999 Monthly Operating Repts for May 1999 for Ccnpp,Units 1 & 2. with ML20206R5871999-04-30030 April 1999 Monthly Operating Repts for Apr 1999 for Ccnpp,Units 1 & 2. with ML20195B3891999-04-30030 April 1999 0 to CENPD-279, Annual Rept on Abb CE ECCS Performance Evaluation Models ML20205N2951999-04-13013 April 1999 Special Rept:On 990314,fire Detection Sys Was Removed from Svc to Support Mod to Replace SRW Heat Exchangers in Unit 2 SRW Room During Unit 2 Refueling Outage.Contingency Measure 15.3.5.A.1 Will Continue Until Fire Detection Sys Restored ML20210T5211999-04-0101 April 1999 Rev 0 to Ccnpp COLR for Unit 2,Cycle 13 ML20205P5441999-03-31031 March 1999 Monthly Operating Repts for Mar 1999 for Calvert Cliffs Nuclear Power Plant,Units 1 & 2.With ML20204H6471999-03-21021 March 1999 SER Re License Renewal of Calvert Cliffs Nuclear Power Plant,Units 1 & 2 ML20207M8321999-02-28028 February 1999 Monthly Operating Repts for Feb 1999 for Calvert Cliffs Nuclear Power Plant.With ML20203D4311999-02-0505 February 1999 Safety Evaluation Accepting Procedure Established for long-term Corrective Action Plan Related to Containment Vertical Tendons ML20199G4671999-01-20020 January 1999 SER Accepting USI A-46 Implementation for Plant ML20206Q3221999-01-11011 January 1999 Special Rept:On 981226,wide Range Noble Gas Effluent RM Was Removed from Operable Status.Caused by Failure of mid-range Checksource to Properly Reseat.Completed Maint & post-maint Testing & RM Was Returned to Operable Status on 990104 ML20207L0451999-01-0808 January 1999 Cost-Benefit Risk Analyses:Radwaste Sys for Light Water Reactors ML20199F4781999-01-0808 January 1999 Safety Evaluation Concluding That Bg&E Performed Appropriate Evaluations of Operational Configurations of safety-related power-operated Gate Valves to Identify Valves Susceptible to Pressure Locking.Concludes GL 95-07 Actions Were Addressed ML20198S7591999-01-0707 January 1999 SER Accepting Quality Assurance Program Description Change for Calvert Cliffs Nuclear Power Plant,Units 1 & 2 ML20207M2281998-12-31031 December 1998 1998 Annual Rept for Bg&E. with ML20199E2931998-12-31031 December 1998 Monthly Operating Repts for Dec 1998 for Calvert Cliffs Npp. with ML20206R9911998-12-0808 December 1998 Rept of Changes,Tests & Experiments (10CFR50.59(b)(2)). with ML20198B2631998-11-30030 November 1998 Monthly Operating Repts for Nov 1998 for Calvert Cliffs Nuclear Power Plant,Units 1 & 2.With ML20195H1001998-11-16016 November 1998 Safety Evaluation of First Containment Insp Interval Iwe/Iwl Program Alternative ML20196E2211998-10-31031 October 1998 Non-proprietary Rev 03-NP to CEN-633-NP, SG Tube Repair for Combustion Engineering Designed Plant with 3/4 - .048 Wall Inconel 600 Tubes Using Leak Limiting Alloy 800 Sleeves ML20195E5281998-10-31031 October 1998 Monthly Operating Repts for Oct 1998 for Calvert Cliffs Nuclear Power Station,Units 1 & 2.With ML20154Q7191998-10-21021 October 1998 Special Rept:On 980923,unit 1 Wrngm Was Removed from Operable Status.Caused by Failure of Process Flow Transducer.Completed Maint to Remove Process Flow Transducer Input to Wrngm Microprocessor & Completed Formal Evaluation ML20154G3931998-10-0505 October 1998 Safety Evaluation Concluding That Flaw Tolerance Evaluation for Assumed Flaw in Inboard Instrument Weld of Pressurizer Meets Rules of ASME Code ML20154M5841998-09-30030 September 1998 Monthly Operating Repts for Sept 1998 for Calvert Cliffs Nuclear Plant,Units 1 & 2.With ML20153C2571998-09-18018 September 1998 Special Rept:On 980830,wide Range Noble Gas Monitor (Wrngm) Channel Was Removed from Operable Status.Caused by Need to Support Performance of Required 18-month Channel Calibr.Will Return Wrngm to Operable Status by 980925 ML20153C1091998-09-18018 September 1998 Part 21 Rept Re Defective Capacity Control Valves.Trentec Personnel Have Been in Contact with Bg&E Personnel Re Condition & Have Requested Potentially Defective Valves ML20151U5441998-09-0404 September 1998 Bg&E ISI Summary Rept for Calvert Cliffs ML20151T5281998-09-0101 September 1998 Special Rept:On 980819,declared Rv Water Level Monitor Channel a Inoperable.Caused by Failure of Three Heated Junction Thermocouples (Sensors) in Lower Five Sensors. Channel a & B Rv Water Level Probes Will Be Replaced ML20151Y1191998-08-31031 August 1998 Monthly Operating Repts for Aug 1998 for Calvert Cliffs Nuclear Power Plant Units 1 & 2.With ML20237D4981998-08-19019 August 1998 Safety Evaluation Accepting Licensee Request for Extension of Second ten-year Inservice Insp Interval ML18066A2771998-08-13013 August 1998 Part 21 Rept Re Deficiency in CE Current Screening Methodology for Determining Limiting Fuel Assembly for Detailed PWR thermal-hydraulic Sa.Evaluations Were Performed for Affected Plants to Determine Effect of Deficiency ML20237B9371998-07-31031 July 1998 Monthly Operating Repts for July 1998 for Calvert Cliffs Nuclear Power Plant ML20237D5941998-07-22022 July 1998 Rev 2 to Ccnpp COLR for Unit 2,Cycle 12 ML20236L7521998-07-0606 July 1998 Safety Evaluation Granting Bg&E 980527 Request for Relief from Requirement of Section IWA-5250 of ASME Code for Calvert Cliffs Unit 2.Alternatives Provide Reasonable Assurance of Operational Readiness ML20236F7791998-06-30030 June 1998 Safety Evaluation Authorizing Request for Temporary Relief from Requirement of Subsection IWA-5250 of ASME Code,Section XI for Plant,Unit 1 ML20236R0881998-06-30030 June 1998 Monthly Operating Repts for June 1998 for Calvert Cliffs Nuclear Power Plant,Units 1 & 2 ML20236X3101998-06-19019 June 1998 Rev 1 to Calvert Cliffs Nuclear Power Plant COLR for Unit 2,Cycle 12 ML20249A9571998-06-15015 June 1998 Special Rept:On 980430,fire Detection Sys Was Removed from Svc to Support Mod to Purge Air Sys 27-foot Elevation & 5-foot Elevation East Piping Penetration Rooms.Installed Temporary Alteration & Returned Fire Detection Sys to Svc ML20249A7711998-05-31031 May 1998 Monthly Operating Repts for May 1998 for Ccnpp,Units 1 & 2 1999-09-30
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RosenT E. DenTox Baltimore Gas and Electric Company Vice President Calvert Cliffs Nuclear Power Plant Nuclear Energy 1650 Calven Cliffs Parkway Lusby, Maryland 20657 410 586-2200 Eri.4455 loca; 4t0 260-4455 Baltimore January 10,1995 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION: Document Control Desk
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 10 CFR Part 21 Report; Non-Conservative Modeling of Reactor Coolant System Sensible IIeat For Containment Pressure Resnonse Safety Analysis During a review of our Updated Final Safety Analysis Report Safety Analysis concerning containment pressure response, we determined the Bechtel analysis of the long-term cooling phase of a loss of coolant accident did not model heat transfer from Reactor Coolant System (RCS) metal components to the RCS coolant. This omission potentially results in a non-conservative calculated containment temperature during l a specific time period of the analysis (after containment peak temperature until several days after the l cvent). Although we have concluded this non-conservative assumption has no safety significance for Calvert Cliffs, we are reporting it under Part 21 because this problem may potentially represent a safety consequence to other licensees who use similar methodologies.
1 Bechtel has informed us that they are evaluating the generic implications, if any, of this modeling omission and will report the results of their evaluation to us.
A verbal notification and written summary were submitted to the Nuclear Regulatory Commission Operations Center via facsimile on December 9,1994.
Should you have any questions regarding this matter, we will be pleased to discuss them with you.
Very truly yours, es
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_%-t Control Desk January 10,1995 Page 2 cc: D. A. Brune, Esquire ,
J. E. Silberg, Esquire L. B. Marsh, NRC D. G. Mcdonald, Jr.,'NRC T. T. Martin, NRC P. R. Wilson, NRC R. I. McLean, DNR J. H. Walter, PSC t
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. 10 CFR PART 21 REPORT; NON-CONSERVATIVE MODELING OF RCS SENSIBLE HEAT FOR CONTAINMENT PRESSURE RESPONSE SAFETY ANALYSIS COULD RESULT IN A SLIGHT INCREASE IN POST-ACCIDENT CONTAINMENT TEMPERATURE Calvert Cliffs Nuclear Power Plant, Units I and 2 Docket Nos. 50-317 and 50-318 1
(i) Name and address ofindividual making notification:
R. E. Denton, Vice President, Nuclear Energy Baltimore Gas and Electric Company ,
Calvert Cliffs Nuclear Power Plant l 1650 Calvert Cliffs Parkway Lusby, MD 20657-4702 l
(ii) Basic Component Affected: l l
Updated Final Safety Analysis Report Chapter 14.20, " Containment Pressure Response."
Specifically the long-term cooling phase modeled by Bechtel's Containment Pressure and Temperature Transient Analysis (COPATTA) Code. ;
(iii) Firms Supplying Component: !
Bechtel Power Corporation (iv) Nature of Defect:
Chapter 14.20 of our Updated Final Safety Analysis Report (UFSAR), " Containment Pressure Response," is an analysis of the pressure and temperature response of our containments to design basis accidents such as a main steam line break or a loss of coolant accident (LOCA). A spectrum of Reactor Coolant System (RCS) break sizes were considered to determine the worst condition of RCS mass and energy releases in combination with sensible and shutdown heat sources during the blowdown phase of a LOCA. The containment response to these breaks was analyzed assuming various limiting single failures.
The RCS blowdown transient results in primary containment pressure and temperature peaks as a result of the mass and energy transferred from the reactor core to the primary coolant and to the containment atmosphere. During the refill and reflood phases of the accident scenario, heat in the steam generator water mass is transferred to the primary coolant via a reverse heat flow and then into the containment atmosphere. In addition, safety injection water reflooding into an uncovered core and ti.e hot RCS system picks up heat from those sources and deposits it into the Containment as saturated or even superheated steam.
The mass and energy transfer from the RCS for various phases of the accident are calculated by Combustion Engineering (CE) and Bechtcl. The blowdown phase of the LOCA is modeled using the CE FLASil code, the refill and reflood phases by the CE FLOOD code, and the long-term 1
. 10 C7R PART 21 REPORT; NON-CONSERVATIVE MODELING OF RCS SENSIBLE HEAT FOR CONTAINMENT PRESSURE RESPONSE SAFETY ANALYSIS COULD RESULT IN A SLIGHT INCREASE IN POST-ACCIDENT l CONTAINMENT TEMPERATURE cooling phase by Bechtel. The mass and energy transfer data is input to Bechtel's Containment Pressure and Temperature Transient Analysis (COPATTA) code for calculation of contaimnent pressure and temperature. During the long-term cooling phase (after reflood) the transfer of sensible heat from the RCS metal back into the coolant is not modeled. When RCS metal sensible heat is included, the result is a higher enthalpy coolant flowing from the RCS break into Containment. He higher enthalpy coolant flowing into the containment leads to slightly higher containment temperatures and pressures for several days after their peaks. Preliminary analysis indicates the problem has no effect on containment peak pressure or peak temperature. We have concluded that there are no adverse effects to our environmental qualification program.
(v) Date on Which Defect Was Identified:
He problem was identified by BGE during a review of the UFSAR Chapter 14.20 Safety Analysis, and documented on an Issue Report on November 9,1994.
(vi) Number and Location of Components:
Not applicable.
(vii) Corrective Actions Taken:
We have asked CE to provide new mass and energy transfer data that accounts for sensible heat transfer from the RCS metal to the coolant. The revised data produced by CE will be provided to Bechtel to produce revised containment pressure and temperature response curves. He results of the revised containment response curves are expected to show:
A. Containment primary peak pressure and temperature will be unaffected, l
B. The intermediate containment temperature will be increased by less than 2'F.
1 C. He containment temperature and pressure will be essentially unaffected beginning several days after the start of the event. ,
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%c results of this reanalysis are being evaluated for impact on other aspects of our current Ocensing basis. The most significant potential impact was the increased load on our SRW system l via the containment air coolers. We have no current operability concerns due to low ultimate heat l sink temperatures at the present time and expect that the final reanalysis will show the real effect !
on our current safety analysis margins will be minimal.
Bechtel has informed us that they are evaluating the generic implications, if any, of this modeling omission and will report the results of their evaluation by January 20,1995.
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