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Category:CORRESPONDENCE-LETTERS
MONTHYEARML20138H3831999-10-25025 October 1999 Forwards Draft Model of Renewed License for Calvert Cliffs, Unit 2 to Illustrate How List of Minimum Requirements Could Be Incorporated Into License Condition ML20217M9991999-10-22022 October 1999 Forwards Response to NRC 990930 RAI Re Void Swelling Degradation Mechanism,Per License Renewal Application for Ccnpp,Units 1 & 2 ML20217M1721999-10-19019 October 1999 Forwards NRC Rept Number 17, Requal Tracking Rept Form Operator Licensing Tracking Sys.Rept Was Used by NRC to Schedule Requalification Exam for Operators & Record Requal Pass Dates ML20212M2631999-10-0404 October 1999 Informs That Staff Concluded That Licensee Responses to GL 97-06 Provides Reasonable Assurance That Condition of Util SG Internals in Compliance with Current Licensing Bases for Calvert Cliffs Nuclear Power Plant ML20216J8671999-10-0101 October 1999 Forwards Rev 52 to QA Policy for Calvert Cliffs Nuclear Power Plant. Rev Accurately Presents Changes Made Since Previous Submittal,Necessary to Reflect Info & Analyses Submitted to NRC or Prepared,Per to NRC Requirements ML20212J7811999-09-30030 September 1999 Requests That Licensee Address Potential Aging Mgt Issue Re Effects of Void Swelling of Rv Internals by Making Plant Specific Commitment to Implement Focused age-related Degradation Insp for Evidence of Void Swelling in Future ML20212J5611999-09-29029 September 1999 Informs That on 990916,NRC Completed mid-cycle Plant Performance Review of Calvert Cliffs.No Areas in Which Util Performance Warranted Addl Insp Beyond Core Insp Program Identified.Historical Listing of Plant Issues,Encl ML20216H7831999-09-28028 September 1999 Forwards Addl Info Re NRC SER for Ccnpp,Units 1 & 2,per License Renewal Application ML20212D5361999-09-20020 September 1999 Forwards Rev 1 to Calculation CA04048, Fuel Handling Accident During Reconstitution, as Agreed During 990909 Telcon ML20212C1861999-09-15015 September 1999 Requests That NRC Complete Review of TR CED-387-P,Rev 00-P, Abb Critical Heat Flux Correlations for PWR Fuel, by 000201.Util Expects to Use ABB-NV Correlation for Current non-mixing Vane Fuel in Reload Analyses in 2000 for Ccnpp ML20212A2001999-09-0808 September 1999 Forwards Insp Repts 50-317/99-06 & 50-318/99-06.Two Violations Being Treated as Noncited Violations ML20211N8971999-09-0707 September 1999 Responds to Ltr to D Rathbun of NRC Dtd 990720,in Which Recipient Refers to Ltr from Wc Batton Expressing Support on Renewal Application of Baltimore Gas & Electric Co for Calvert Cliffs Plants ML20211H9841999-08-31031 August 1999 Provides Comments Re Data Entered in Rvid for Ccnpp,Units 1 2,per GL 92-01,Rev 1,Suppl 1, Reactor Vessel Structural Integrity ML20211K3091999-08-27027 August 1999 Informs That During 990826 Telcon,L Briggs & B Bernie Made Arrangements for NRC to Inspect Licensed Operator Requalification Program at Calvert Cliffs Npp.Insp Planned for Wk of 991025 ML20211J1611999-08-17017 August 1999 Documents Bg&E Consultations with MD Dept of Natural Resources Re Potential Impacts to Chesapeake Bay Critical Area & Forest Interior Dwelling Bird Habitat,Per Ccnpp License Renewal.Telcons Ref Satisfy Consulting Requirement ML20210V1181999-08-17017 August 1999 Forwards Toxic Gases Calculations for Control Room Habitability,As Discussed During 990713 Telcon.Util Will Make Final Submittal for Toxic Gases After NRC Has Completed Review of ARCON96 ML20210T5061999-08-16016 August 1999 Forwards Rev 0 to Ccnpp COLR for Unit 2,Cycle 13, Per Plant TS 5.6.5 ML20210U2761999-08-13013 August 1999 Forwards Listed Info Re Guarantee of Payment of Deferred Premiums for Ccnpp,Units 1 & 2,IAW 10CFR140.21 Requirements ML20210S8101999-08-12012 August 1999 Forwards Application Requesting Renewal of License for Mv Seckens,License SOP-10369-2.Without Encl ML20210S8131999-08-12012 August 1999 Forwards Summary of Various Open Licensing Actions for Bg&E That Were Completed During Unit 2 Refueling Outage Ending 990506 ML20210S7901999-08-12012 August 1999 Forwards semi-annual Fitness for Duty Program Performance Data for Period of 990101-990630,IAW 10CFR36.71(d) ML20210Q1941999-08-11011 August 1999 Informs That Info Submitted in 981130 Application Re CEN-633-P,Rev 03-P,dtd Oct 1998,marked Proprietary,Will Be Withheld from Public Disclosure,Per 10CFR2.790(b)(5) & Section 103(b) of AEA of 1954,as Amended ML20210N5881999-08-0606 August 1999 Forwards ISI Rept for Ccnpp,Unit 2,fulfilling Intentions & Requirements Stated in Program Plan & Commitment to Comply with ASME Code Section XI ISI Requirements ML20210N5471999-08-0505 August 1999 Requests That License SOP-10031-3,for DF Theders,Be Removed from Active Files for Ccnpp,Due to Individual Being Reassigned to Position No Longer Requiring License ML20210N5491999-08-0505 August 1999 Requests That License SOP-10371-2,for RW Scott,Be Renewed IAW 10CFR55.57.Individual Has Satisfactorily Discharged License Responsibilities Competently & Safely.Without Application ML20210N1291999-08-0505 August 1999 Forwards NRC Response to W Batton Ltr Expressing Support of Renewal Application for Calvert Cliffs Plants as Requested in Ltr ML20210N9291999-08-0404 August 1999 Forwards Clarification to Initial Response to Biennial Rept on Status of Decommissioning Funding,As Required by 10CFR50.75(f)(1) ML20211C0951999-07-30030 July 1999 Expresses Appreciation for Participation in Y2K Training & Tabletop Exercise Held on 990714 ML20211B5381999-07-30030 July 1999 Expresses Appreciation for Support in Y2K Training & Tabletop Exercise Held on 990714.Suggests Referral to NRC Y2K Web Site to View Issues & Lessons from Tabletop That Will Be Tracked by NRC ML20210J0741999-07-30030 July 1999 Expresses Appreciation for Participation in Y2K Training & Tabletop Exercise on 990714.Suggests Referral to NRC Y2K Web Site to View Issues & Lessons from Tabletop That Will Be Tracked by Nrc.Web Site Should Reflect Info within 2 Wks ML20211C3251999-07-30030 July 1999 Expresses Appreciation for Participation in Y2K Training & Tabletop Exercise Held on 990714 ML20210E4941999-07-23023 July 1999 Informs That 1999 Emergency Response Plan Exercise Objectives Is Scheduled for Wk of 991025.Exercise Scenario Will Test Integrated Capability & Major Portion of Elements Existing within Emergency Response Plan ML20210D0911999-07-22022 July 1999 Responds to to Chairman Jackson Referring to Ltr from New 7th Democratic Civic Club,Inc.Forwards Staff Response to W Batton,President of New 7th Democratic Civic Club,Inc ML20210C5011999-07-21021 July 1999 Informs That SL Walters,License OP-10096-3 & CC Zapp,License Number SOP-2188-9,have Been Reassigned within Organization & No Longer Require NRC License,Per 10CFR50.74(a).Removal of Subject Licenses from Active Files for Ccnpp,Requested ML20210A5021999-07-20020 July 1999 Responds to ,Expressing Support for Renewal of Operating Licenses for Calvert Cliffs Plant & to Concerns Re Lack of Specificity for License Renewal Regulations & Length of Time Set Aside for Public Comment ML20211N9101999-07-20020 July 1999 Forwards Correspondence Author Received from New 7th Democratic Club Civic,Inc Raising Some Serious Concerns About Renewal of Nuclear Reactor Licenses for Calvert Cliffs Power Plant ML20210C2681999-07-20020 July 1999 Forwards Certified Copy of Listed Nuclear Liability Policy Endorsement,Per 10CFR140.15(e) ML20210C8461999-07-19019 July 1999 Informs That CF Farrow,License OP-10648-1,will No Longer Be Employed with Bg&E,As of 990709,per 10CFR50.74(a).Removal of Subject License from Active Files for Ccnpp,Requested ML20209J5171999-07-16016 July 1999 Forwards Comments from Accuracy Review of License Renewal Application SER ML20210B7651999-07-15015 July 1999 Forwards SER Denying Licensee Proposed TS Amend Dtd 981120, to Delete TS Requirements for Tendon Surveillance & Reporting Because TS Requirements Duplication of Requirements in 10CFR50.55a.Notice of Denial Encl ML20209G2081999-07-13013 July 1999 Forwards Insp Repts 50-317/99-05 & 50-318/99-05 on 990509- 0626.No Violations Noted ML20210A6311999-07-0606 July 1999 Discusses Closure of TACs MA0532 & MA0533 Re Response to Requests for Addl Info to GL 92-01,rev1,suppl 1, Reactor Vessel Structural Integrity, for Plant,Units 1 & 2 ML20209C1391999-07-0202 July 1999 Forwards Responses to Open & Confirmatory Items Based on Review of SER for Bg&E Application for Renewal of Operating Licenses for Calvert Cliffs.Bg&E Intends to Forward Comments Based on Accuracy Verification in Near Future ML20210D1531999-06-30030 June 1999 Informs of Receipt of from New 7th Democratic Civic Club,Inc Expressing Support for License Renewal. Requests Consideration in Addressing Concerns & Recommendations ML20209B5781999-06-29029 June 1999 Submits Response to GL 98-01, Y2K Readiness of Computer Sys at Nuclear Power Plants. GL 98-01 Requested Response on Status of Facility Y2K Readiness by 990701.Disclosure Encl ML20210D1741999-06-24024 June 1999 Expresses Opinions on Renewal of Nuclear Reactor Licenses Re Plant & Support Renewal Application of Bg&E.Requests That NRC Revise Procedures to Allow Sufficient Time for Public to Review,Evaluate & Respond to Info ML20211H8431999-06-23023 June 1999 Ack Participation of Calvert Cliffs Nuclear Engineering Dept in NRC Cooperative Research Project with Univ of Virginia. Copy of Relevant Portion of NRC Cooperative Agreement with Univ of Virginia Encl ML20196C6831999-06-21021 June 1999 Discusses Proposed Alternative Submitted by Bg&E for Calvert Cliffs NPP to Requirements of 10CFR50.55a(g)(4) in Regard to Compliance with Latest Approved Edition of ASME Code,Section XI for Third Ten Year Insp Interval Beginning on 990701 ML20196C4291999-06-21021 June 1999 Forwards Rev to ERDS Data Point Library for Ccnpp,Unit 2,per 10CFR50,App E,Section VI.3.a.Table Provides Brief Summary of Changes ML20195J8271999-06-16016 June 1999 Ack Receipt of to Jackson,Chairman of NRC Re Environ Impacts of Increased Patuxtent River Complex Flight Operations on Ccnpp.Clarification & Correction of Listed Statement Found on Page Two,Provided 1999-09-08
[Table view] Category:INCOMING CORRESPONDENCE
MONTHYEARML20217M9991999-10-22022 October 1999 Forwards Response to NRC 990930 RAI Re Void Swelling Degradation Mechanism,Per License Renewal Application for Ccnpp,Units 1 & 2 ML20216J8671999-10-0101 October 1999 Forwards Rev 52 to QA Policy for Calvert Cliffs Nuclear Power Plant. Rev Accurately Presents Changes Made Since Previous Submittal,Necessary to Reflect Info & Analyses Submitted to NRC or Prepared,Per to NRC Requirements ML20216H7831999-09-28028 September 1999 Forwards Addl Info Re NRC SER for Ccnpp,Units 1 & 2,per License Renewal Application ML20212D5361999-09-20020 September 1999 Forwards Rev 1 to Calculation CA04048, Fuel Handling Accident During Reconstitution, as Agreed During 990909 Telcon ML20212C1861999-09-15015 September 1999 Requests That NRC Complete Review of TR CED-387-P,Rev 00-P, Abb Critical Heat Flux Correlations for PWR Fuel, by 000201.Util Expects to Use ABB-NV Correlation for Current non-mixing Vane Fuel in Reload Analyses in 2000 for Ccnpp ML20211H9841999-08-31031 August 1999 Provides Comments Re Data Entered in Rvid for Ccnpp,Units 1 2,per GL 92-01,Rev 1,Suppl 1, Reactor Vessel Structural Integrity ML20210V1181999-08-17017 August 1999 Forwards Toxic Gases Calculations for Control Room Habitability,As Discussed During 990713 Telcon.Util Will Make Final Submittal for Toxic Gases After NRC Has Completed Review of ARCON96 ML20210T5061999-08-16016 August 1999 Forwards Rev 0 to Ccnpp COLR for Unit 2,Cycle 13, Per Plant TS 5.6.5 ML20210U2761999-08-13013 August 1999 Forwards Listed Info Re Guarantee of Payment of Deferred Premiums for Ccnpp,Units 1 & 2,IAW 10CFR140.21 Requirements ML20210S7901999-08-12012 August 1999 Forwards semi-annual Fitness for Duty Program Performance Data for Period of 990101-990630,IAW 10CFR36.71(d) ML20210S8131999-08-12012 August 1999 Forwards Summary of Various Open Licensing Actions for Bg&E That Were Completed During Unit 2 Refueling Outage Ending 990506 ML20210S8101999-08-12012 August 1999 Forwards Application Requesting Renewal of License for Mv Seckens,License SOP-10369-2.Without Encl ML20210N5881999-08-0606 August 1999 Forwards ISI Rept for Ccnpp,Unit 2,fulfilling Intentions & Requirements Stated in Program Plan & Commitment to Comply with ASME Code Section XI ISI Requirements ML20210N5491999-08-0505 August 1999 Requests That License SOP-10371-2,for RW Scott,Be Renewed IAW 10CFR55.57.Individual Has Satisfactorily Discharged License Responsibilities Competently & Safely.Without Application ML20210N5471999-08-0505 August 1999 Requests That License SOP-10031-3,for DF Theders,Be Removed from Active Files for Ccnpp,Due to Individual Being Reassigned to Position No Longer Requiring License ML20210N9291999-08-0404 August 1999 Forwards Clarification to Initial Response to Biennial Rept on Status of Decommissioning Funding,As Required by 10CFR50.75(f)(1) ML20210E4941999-07-23023 July 1999 Informs That 1999 Emergency Response Plan Exercise Objectives Is Scheduled for Wk of 991025.Exercise Scenario Will Test Integrated Capability & Major Portion of Elements Existing within Emergency Response Plan ML20210C5011999-07-21021 July 1999 Informs That SL Walters,License OP-10096-3 & CC Zapp,License Number SOP-2188-9,have Been Reassigned within Organization & No Longer Require NRC License,Per 10CFR50.74(a).Removal of Subject Licenses from Active Files for Ccnpp,Requested ML20211N9101999-07-20020 July 1999 Forwards Correspondence Author Received from New 7th Democratic Club Civic,Inc Raising Some Serious Concerns About Renewal of Nuclear Reactor Licenses for Calvert Cliffs Power Plant ML20210C2681999-07-20020 July 1999 Forwards Certified Copy of Listed Nuclear Liability Policy Endorsement,Per 10CFR140.15(e) ML20210C8461999-07-19019 July 1999 Informs That CF Farrow,License OP-10648-1,will No Longer Be Employed with Bg&E,As of 990709,per 10CFR50.74(a).Removal of Subject License from Active Files for Ccnpp,Requested ML20209J5171999-07-16016 July 1999 Forwards Comments from Accuracy Review of License Renewal Application SER ML20209C1391999-07-0202 July 1999 Forwards Responses to Open & Confirmatory Items Based on Review of SER for Bg&E Application for Renewal of Operating Licenses for Calvert Cliffs.Bg&E Intends to Forward Comments Based on Accuracy Verification in Near Future ML20210D1531999-06-30030 June 1999 Informs of Receipt of from New 7th Democratic Civic Club,Inc Expressing Support for License Renewal. Requests Consideration in Addressing Concerns & Recommendations ML20209B5781999-06-29029 June 1999 Submits Response to GL 98-01, Y2K Readiness of Computer Sys at Nuclear Power Plants. GL 98-01 Requested Response on Status of Facility Y2K Readiness by 990701.Disclosure Encl ML20210D1741999-06-24024 June 1999 Expresses Opinions on Renewal of Nuclear Reactor Licenses Re Plant & Support Renewal Application of Bg&E.Requests That NRC Revise Procedures to Allow Sufficient Time for Public to Review,Evaluate & Respond to Info ML20196C4291999-06-21021 June 1999 Forwards Rev to ERDS Data Point Library for Ccnpp,Unit 2,per 10CFR50,App E,Section VI.3.a.Table Provides Brief Summary of Changes ML20195J6591999-06-16016 June 1999 Submits Proposed Alternative to Requirements of 10CFR50.55a(g)(4) (Automatic Compliance with Latest Approved Edition of ASME Code Every 120 Months).Proposal Will Apply Third ten-year ISI Interval,Scheduled to Begin 990701 ML20207F0201999-06-0101 June 1999 Forwards Third Interval Inservice Insp Program Plan for Ccnpp,Units 1 & 2, for NRC Review.Plan Satisfies Commitment Contained in Licensee to NRC 05000317/LER-1999-002, Requests That Cover Page for LER 99-002,dtd 990525,be Corrected to Indicate Rept Is Submitted Per Requirements of 10CFR20.2201(b)1999-05-28028 May 1999 Requests That Cover Page for LER 99-002,dtd 990525,be Corrected to Indicate Rept Is Submitted Per Requirements of 10CFR20.2201(b) ML20195B3751999-05-25025 May 1999 Forwards ECCS Codes & Methods Rept, as Required by 10CFR50.46(a)(3)(ii) ML20195B2521999-05-25025 May 1999 Submits Response to RAI Re LAR for Tube Repair Using Leak Limiting Alloy 800 Sleeves for Ccnpp,Units 1 & 2.Test Repts Encl ML20195B2271999-05-24024 May 1999 Forwards Certified Copy of Nuclear Liability Policy NF-216, Endorsement 128 ML20206U3051999-05-19019 May 1999 Submits Written Rept as Required follow-up to Verbal Rept Given to NRC Regional Administrator on 990419 of SG Tube Insps Conducted,Cause of Tube Degradation & Corrective Measures Taken as Result of Insp Findings ML20206U8281999-05-18018 May 1999 Forwards Missing Pages C-30,C-31,C-114 & C-115 from 990319 Response to NRC RAI, Wind Tunnel Modeling of Calvert Cliffs NPP Cpp Project 94-1040. Complete Copy of 1985 Rept, Wind Flows & Dispersion Conditions of Calvert Cliffs, Encl ML20212G9751999-05-12012 May 1999 Forwards Draft write-up Re OI 16 for F Grubelich to Consider ML20206K6921999-05-10010 May 1999 Forwards Certified Copy of Listed Nuclear Liability Policy Endorsements,In Compliance with 10CFR140.15(e).Without Encl ML20206K1711999-05-0707 May 1999 Informs That on 990430 Util Filed Encl Articles of Share Exchange with Maryland Dept of Assessments & Taxation to Form Holding Company,Constellation Energy Group,Inc (Ceg). CEG Is Parent Company of Bg&E ML20206C7521999-04-29029 April 1999 Provides Rept of Number of Tubes Plugged in Calvert Cliffs Unit 2 SGs During Recently Completed Isi,As Required by Calvert Cliffs Unit 1,TS 5.6.9.a ML20212G9891999-04-28028 April 1999 Forwards Current Draft Response to Ci 3.3.2.2-1 to Be Used as Example for OI Vs License Condition Vs Commitment Situation ML20206C7271999-04-28028 April 1999 Forwards Occupational Radiation Exposure Repts for 1998, as Required by Units 1 & 2 Tech Specs 5.6.1 & 6.1 of Isfsi. Repts Contain Tabulation of Number of Station,Util & Other Personnel Receiving Exposures Greater than 100 Mrem ML20206C7211999-04-27027 April 1999 Forwards Addl Info Which Is Being Made Available in Encl Licensed Operators Fitness for Duty Questionnaire.Encl Specifics of Personal Info Are Withheld,Per 10CFR2.790 ML20212G9851999-04-26026 April 1999 Provides Proposed Response to OI 4.1.3-1 for B Elliott to Consider ML20206U6691999-04-26026 April 1999 Advises That Documents Re Operation of Calvert Cliffs Nuclear Power Plant Should Be Addressed to Listed Natl Marine Fisheries Svc Office ML20205F8851999-04-0202 April 1999 Provides First Annual Amend to Bg&E License Renewal Application for Ccnpp,Units 1 & 2,as Required by 10CFR54 ML20205J0691999-04-0202 April 1999 Forwards Response to NRC 990129 RAI Re GL 96-05, Periodic Verification of Design-Basis Capability of Safety-Related Movs ML20205G2971999-04-0101 April 1999 Requests That NRC Complete Review of Rev 0 to CENPD-396-P, Common Qualified Platform TR & Rev 0 to CE-CES-195-P, Software Program Manual for 'Common Q' Sys, by 990930 ML20205D7471999-03-30030 March 1999 Forwards Biennial Rept on Status of Decommissioning Funding, IAW 10CFR50.75(f)(1) ML20207G4391999-03-30030 March 1999 Responds to from Cl Miller,Requesting Assistance of FEMA in Addressing Concerns Received by NRC Involving Offsite Emergency Preparedness at Plant NPP ML20205C4091999-03-26026 March 1999 Submits Info Related to Scope,Risk Mgt & Summary of Risk for Performing Preventive Maintenance on P-13000-2 Unit Transformer Re License Amend 205 1999-09-28
[Table view] |
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_ - _ _ _ _ _ _
- BALTIMORE - I GAS AND )
' ELECTRIC L {
1650 CALVERT CLIFFS PARKWAY . LUSBY, MARYLAND 20657-4702 L
RoDERT E. DENTON vict PacsicENT j NUCLE AR rNERGY (4so) aso-44ss July 7,1993 i
U. S. Nuclear Regulatory Commission Washington, DC 20555 l ATTENTION: Document Control Desk l
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2: Docket Nos. 50-317 & 50-318 Evaluation of Isolation Provisions for Service Water System (TAC Nos. M77301 & M77302)
REFERENCE:
(a) Calvert Cliffs Licensee Event Report 89-23, Revision 2, dated December 14, 1990, Postulated Rupture in Non-Safety-Related Service Water (SRW) Could Cause Failure of Both Safety-Related Subsystems Gentic. ,en:
During a system design review in 1989, we identified a potential vulnerability to the loss of the safety- l related (SR) portion of the Service Water (SRW) System during a Safe Shutdown Earthquake (SSE). This concern was described and a resolution proposed in Licensee Event Report '
(LER) 89-23 (Reference a). As a result of an engineering evaluation performed in response to the issue, we have resolved the concern in a manner different than that described in the LER. This letter explains our resolution.
The SRW System is divided into SR and non-safety-related (NSR) portions. The NSR portion of the -
system serves equipment in the Turbine Building. There are two isolation valves in series between the SR and NSR portions. These valves close automatically upon receipt of a Safety Injection I Actuation Signal and loss of instrument air. However, these valves do not close automatically during
~
a scismic event. This was the concern identified in LER 89-23, and we indicated we would resolve this issue by installing a diverse isolation signal to these valves. We have since determined that automatic isolation of the NSR portion of the system during a seismic event is not a practical solution.
Engineering studies were performed to examine various ways of providing an automatic signal to isolate the SRW System. These proposed modificadons would have resulted in a reduction in overall SRW System reliability. We also evaluated the seismic capabilities of the Turbine Building and the NSR portion of the SRW System. We determined that both the Turbine Building and the NSR piping were rugged enough to withstand an SSE without collapse or gross rupture. During this 9307200156 93OIO I "r' \
PDR ADOCK 05000317 j
l 5 PDR 0
2 0s 0
'\
' . Dctrument Control Desk
. July 7,1993 Page 2 review, five small branch lines were identified as potential break points in NSR SRW piping in the Turbine Building. Supports and pipe routing for these five lines were modified during the last Unit 1 and 2 refueling outages to prevent failure. As a result, the Turbine Building piping.will now withstand an SSE. Further details of this evaluation are presented in the attachment to this letter.
Based on the engineering evaluation described above, our initial assumption of gross failure of the NSR SRW System during a seismic event was unrealistic and overly conservative. We have determined that the SRW System satisfies the appropriate licensing and design criteria for Calvert Cliffs. Specifically, the system design complies with General Design Criteria 2 (draft) in that it is capable of withstanding local natural phenomena and still performing its safety function. The capability of the NSR portion of the SR% System to withstand seismic events without rupture has been evaluated. Therefore, we have provided reasonable assurance that the SRW System will withstand seismic Category I accelerations and remain functional as described in the UFSAR Section 9.5.2.2.
Should you have any further questions regarding this matter, we will be pleased to discuss them with
_you.
Very truly yours, RED /EMT/ PSF /cmt/ dim
[ .
k Attachment l
cc: D. A. Brune, Esquire J. E. Silberg, Esquire R. A. Capra, NRC D. G. Mcdonald, Jr., NRC T. T. Martin, NRC P. R. Wilson, NRC R. I. McLean, DNR J. H. Walter, PSC
'. . ATTACIIMENT TECIINICAL DISCUSSION OF ISSUES CONCERNING ISOLATION OF NON-SAFE 1Y-RELATED SERVICE WATER PIPING AND COMPONENTS IIACKGROUND On December 14, 1990, Licensee Event Report (LER) 89-23 identified the potential for a seismically-induced breach of the non-safety-related (NSR) portion of the Service Water (SRW)
System to cause drainage and failure of the safety-related (SR) portion. This LER reported a postulated, not an actual, event. Our letter to the NRC, dated August 24,1990, stated that our long-term plan to resolve this issue was to " enhance the system's design by providing automatic isolation of the safety-related SRW portion on indication of rupture in the non-safety-related portion." At that time, worst-case damage to the NSR portion of the system was conservatively assumed to be a j double-ended guillotine break.
The SRW System at Calvert Cliffs is described in the Updated Final Safety Analysis Report (UFSAR)in Chapter 9. Unit I and Unit 2 each have an SRW System independent of the other unit.
Except as noted, this letter will discuss a single system with the understanding that the discussion applies equally to either unit. Each unit system has an SR portion in the Auxiliary Building and an NSR portion in the Turbine Building. A simplified diagram is provided as Figure 1.
'Be SR portion of the system is divided into two trains for sing!c-failure protection. In response to Engineering Safety Features Actuation Signal (ESFAS), one train provides cooling water to two containment coolers and the Emergency Diesel Generator (EDG) designated to serve the unit. The other train provides cooling water to 12 EDG (the swing diesel) and the other two containment coolers. These components are not needed for safe shutdown unless a Loss-of-Coolant Accident (LOCA) or Imss of Offsite Power (LOOP) occurs.
The NSR portion is a single loop in the Turbine Building connected to both SR trains. It is isolable from the SR portion on the supply side by two air-operated control valves in series for each train and on the return side by a single, common check valve backed up by another check valve and a manually operated butterfly valve for each train. The control vahes are shut automatically on Safety Injection Actuation Signal (SIAS). Remote manual isolation is possible from the Control Room for other events such as earthquakes or any other incidents that may result in system leakage. A rupture in the NSR portion of the SRW System, taken by itself, is not a significant contributor to risk because the components served are not needed for safe shutdown.
IWALUATION OF AUTO-ISOLATION OPTIONS Our engineering staff evaluated the SRW System with the installed methods of isolation and came to the conclusion that, given the magnitude of the assumed (double-ended guillotine) failure, the isolation system could not be practically redesigned to automatically isolate the SR portion fast enough to avoid SR inventory loss. The options evaluated are described below:
- 1. Detection of a seismic event by use of seismic accelerometers:(Rejected)
We do not feel that existing technology is sufficiently reliable to be used in an SR application. Inadvertent actuation could cause a signalleading to unintentional SRW isolation and subsequent plant trip.
2, System leak detection by use of acoustic pipe monitors:(Rejected)
Existing technology is not sufficiently reliable to be used in an SR application.
I
- - . A'ITACIIMENT I TECIINICAL DISCUSSION OF ISSUES CONCERNING ISOLATION OF NON-SAFET%RELATED SERVICE WATER PIPING AND COMPONENTS
- 3. System leak detection by use of pressure differential: (Rejected)
The pressure differential would not be great enough to act as a reliable indicator.
Use of an orifice installed to create a reliable pressure differential would increase the potential for short duration pump cavitation during normal operation.
- 4. An SRW isolation sicnal cenerated by detectine a low level in the system head tanks:
(Rejected)
Since the spread between the normal operating level and the proposed isolation signal setpoint is not sufilcient to prevent normal operational transients from challenging the setpoint, a higher operating level in the head tank would be necessary and the head tanks would have to be cross-connected. Because the level in the head tank varies during normal operation, setting the operating level higher increases the ,
possibility of operational alarms. Cross-connecting the head tanks is not desired because maintaining system separation would require additional automated control valves. This option would cost between 0.5 and 1.0 million dollars.
- 5. Chance the valve operatine solenoids to a type that would release the valves (the
- valves are fail closed) on LOOP:(Rejected)
This solution would not isolate the NSR portion of the system if there was a release of water inventoiy without a LOOP.
The solutions discussed above, all initially considered viable, were rejected because of high cost, lack of suitable technology, ineffectiveness, or because the change decreased operational safety margin.
SEISMIC WALKDOWNS AND ANALYSES I
The results of the above evaluation led to the need to explore other options for providing an adequate degree of protection against the effects of failure of NSR piping on the SR portion of the SRW System. The most likely initiating mechanism for a large rupture of NSR portion of the SRW System piping :s a severe scismic event. Our review of the Turbine Building structural design revealed that it is a ductile structure with inherent damping and energy absorbing capacity. The building is built to withstand 90 mph winds, thereby resisting lateral loads in excess of UBC seismic requirements. In addition, it is a Seismic Category II structure designed for 0.08g acceleration and the complexity of the structure would result in several significant modes of vibration which would !
serve to reduce the magnitude of the building resonant frequencies. All these factors would limit the building's response to scismic excitation and it would maintain its integrity during a seismic event. l Considering the design of the Turbine Building and the inherent ruggedness of steel piping in general (ASME Code Case N-411), the occurrence of a severe seismic event is not expected to result in a large pipe rupture. Ilowever, since the NSR portion of the SRW System is not seismically qualified (Category I), we conducted a walkdown with a recognized expert in seismic studies. The intent of the walkdown was to identify those locations most likely to be affected by a Safe Shutdown i Earthquake (SSE). The walkdown was conducted in accordance with EPRI guidelines that are l endorsed by the NRC in NUREG-1407. Although these guidelines are not directly applicable to i 2 l l
. '. . A'ITACIIMENT TECilNICAL DISCUSSION OF ISSUES CONCERNING ISOLATION OF NON SAFITIY RELATED SERVICE WATER PIPING AND COMPONENTS piping systems, the guidance on conduct of scismic walkdowns and the analysis of results is usefulin this instance. Our consultant's conclusions are summarized below:
- 1. The piping is supported in "a normal flexible manner for fossil fueled power plants and other heavy industrial facilities, even for those located in earthquake-prone regions like California."
- 2. Use of studies of industrial piping for application to nuclear power plants is consistent with the 1985 NRC report " Summary and Evaluation of IIistorical Strong-Motion Earthquake Seismic Response and Damage to Aboveground Industrial Piping," NUREG-1061.
- 3. Welded steel piping such as that in question "does not fail in carthquakes from its own inertialloads." This conclusion is supported by the NRC/EPRI Piping and Fitting Reliability joint test program.
l
- 4. The points at which failure is likely to occur are at five (for both units) small (3/4"- 2") branch lines due to:
- a. a threaded connection
- b. branch line restraints l
- c. branch line contact with a structural member or other interference due to movement l of the main pipe.
l S. It would be a conservative approach to assume that all five branch pipes (four in Unit 1 and I one in Unit 2) will break at once (but that the breaks would not be totally open; i.e., cracks or i splits). I
- 6. There is no need "to consider it credible for the Calvert Cliffs safe shutdown earthquake to cause loss of pressure boundary in the large bore pipes"(this conclusion negates the need to consider a double-ended guillotine break of the 14" main pipe as a credible failure).
SUMMARY
We considered options for automatic isolation of the NSR from the SR portion of the system on a seismic event. We concluded that, although we might achieve automatic isolation, we would do so at some reduction of safety margin.
A reevaluation of the system found that the system piping and the Turbine Building could withstand an SSE. We identified five branch lines (total in both units) that were vulnerable to seismic-induced damage. These were fixed by rerouting and adding supports. This proved to be the most cost-effective and least intrusive of all the solutions.
l 1
3
FIGURE 1 .
SIMPLIFIED SRW SYSTEM .-
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O 1 r 1 r l AUXILIARY BUILDING l LOADS l 1
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ISOLATION l CHECK VALVES I
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