Similar Documents at Maine Yankee |
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Category:CORRESPONDENCE-LETTERS
MONTHYEARML20217N8371999-10-13013 October 1999 Forwards Summary of Changes Made to Maine Yankee Defueled Security Plan,Iaw 10CFR50.54(p)(2).Without Encl ML20217J0241999-10-13013 October 1999 Documents 991005 Telcon Between NRC & Util to Address All of Areas Identified in Reg Guide 1.179 & NUREG-1700 Re Final Survey Plan Except for One Area ML20212F4321999-09-24024 September 1999 Responds to 990921 e-mail to E Poteat,Requesting Waiver of Late Charges of Listed Amount for Annual Fee Invoice AR0431-99.Request Denied Because 10CFR15.37 Does Not Provide for Waiver Based on Info Provided in e-mail ML20212M2431999-09-22022 September 1999 Expresses Concern Re NRC Consideration of Adoption of Policy Based on Requests from Licensees,To Allow as Part of Decommissioning of Nuclear Power Plants & Demolition of Onsite Structures at Reactor Plant Sites ML20212E4611999-09-20020 September 1999 Responds to Concerning Possible Involvement in Weekly Telephone Calls NRC Staff Has with Maine Yankee Staff ML20212F1361999-09-20020 September 1999 Confirms That NMSS Has Received 990916 Submittal & Will Be Included as Attachment to Commission Paper Along with State of Maine Submittal ML20212F2521999-09-20020 September 1999 Confirms That NMSS Has Received 990916 Submittal & Will Be Included as Attachment to Commission Paper Along with State of Maine Submittal ML20212B7011999-09-14014 September 1999 Submits Comments & Raises Questions Re Generation of White Paper for Commission to Decide Merits of Rubberization ML20212A5911999-09-0808 September 1999 Responds to 990816 e-mail & 990901 Telcon with Respect to Comments Re Decommissioning of Maine Yankee Site.Concerns Raised with Respect to Status of Fuel at Maine Yankee Have Been Raised in Previous Ltrs to Us NRC ML20211M9371999-08-30030 August 1999 Addresses Two Issues Raised in s to Senator Collins & Governor a King That Relate to Construction of ISFSI at Maine Yankee ML20212B2181999-08-30030 August 1999 Responds to Re 990707 Message from N Allen Re Transportation Incident Involving Shipment from Maine Yankee Nuclear Power Plant ML20212E4841999-08-27027 August 1999 Informs That at 990429 Meeting of Myap Community Advisory Panel,R Shadis,Asked If Given Lack of Resident Inspectors & Limited NRC-license Review Correspondence,If Shadis Could Take Part in Weekly NRC Conference Calls with Licensee ML20216F1891999-08-26026 August 1999 Forwards Copies of Maine Yankee & Yankee Rowe Refs Listed, Supporting Industry Position That Branch Technical Position Asb 9-2 Methodology over-estimates Spent Fuel Decay Heat ML20211C0591999-08-19019 August 1999 Forwards Addl Justification for Proprietary Request Re 990809 Submittal Info on Maine Yankee License Termination Plan ML20212A5981999-08-16016 August 1999 Expresses Appreciation for with Respect to e-mail Message Re Site Release Criteria Standards Can Never Be Verified Using Existing Database ML20211D7041999-08-0909 August 1999 Forwards Rev 17 of Maine Yankee Defueled Safety Analysis Rept (Dsar), Per 10CFR50.71 & 10CFR50.4 ML20217M6501999-08-0909 August 1999 Responds to 990719 E-mail Re Cleanup Stds at MYAPC Station & Verification of Meeting Cleanup Stds.Informs That NRC Criteria for Licensing NPPs Contained in 10CFR50 & That 10CFR50.82 Addresses Requirements for License Termination ML20210Q7201999-08-0909 August 1999 Forwards non-proprietary & Proprietary Draft Documents Re Info on Myap License Termination Plan & Diskette.Proprietary Info & Diskette Withheld ML20212B2271999-08-0606 August 1999 Discusses Concerns Re Recent Incindent Involving Transport of Nuclear Matl from Maine Yankee ML20210M8171999-08-0505 August 1999 Forwards Draft License Termination Plan/Amend Plan for Maine Yankee Atomic Power Co, to Enhance Dialogue Between Various Stakeholders & Provide Springboard for Clarifying Mutual Expectations.With Three Oversize Drawings ML20210L2211999-08-0202 August 1999 Forwards Two Copies of Objectives & Sequence of Events for Maine Yankee Emergency Preparedness Exercise for 990922. Without Encl ML20210G3751999-07-28028 July 1999 Ack Receipt of June 30th Ltr That Responded to EDO Backfit Appeal Determination Re Bdba in Sfps.Staff Completed All Actions Associated with Backfit Appeal & Awaiting for New Info for Consideration Prior to Taking Addl Action ML20216D4311999-07-19019 July 1999 Informs That Util Intends to Construct ISFSI Located on Owner Controlled Property Currently Part of Maine Yankee Reactor Site ML20217M6571999-07-19019 July 1999 Expresses Concern Re Verification of Cleanup Stds at Maine Yankee Atomic Power Co Power Station ML20210C6271999-07-15015 July 1999 Forwards Draft Site Characterization Summary in Support of 10CFR50 License Termination & Copy of Latest Decommissioning Schedule with Milestones Identified.Info Submitted Per License Termination Plan ML20196K4751999-07-0606 July 1999 Informs That Confirmatory Orders ,830314,840614 & 960103 Have Been Rescinded.Staff Determined That Due to Permanently Shutdown & Defueled Status of Facility,Orders No Longer Necessary for Safe Operation & Maint.Se Encl ML20210G3981999-06-30030 June 1999 Discusses Review of Ltr Re Maine Yankee Backfit Appeal with Respect to Emergency Plan Exemptions for Decommissioning Plants ML20209C7731999-06-30030 June 1999 Responds to EDO Backfit Appeal Determination Re Emergency Plan Exemptions for Decommissioning Plants ML20209B4611999-06-29029 June 1999 Submits Response to GL 98-01, Y2K Readiness of Computer Sys at Nuclear Power Plants. Plant Is Y2K Ready.Contingency Plans Developed to Mitigate Potential Impact of non-plant Y2K-induced Events ML20196D9191999-06-22022 June 1999 Informs That NRC Has Completed Review of Issues Raised in of Appeal to NRC Edo.Submits List Summarizing Actions Taken Since ML20195H1741999-06-15015 June 1999 Forwards Original & Copy of Request for Approval of Certain Indirect & Direct Transfer of License & Ownership Interests of Montaup Electric Co (Montaup) with Respect to Nuclear Facilities Described as Listed ML20207H3371999-06-11011 June 1999 Expresses Appreciation for Participation at 990413 Reactor Decommissioning Public Meeting & Responds to Concern Re Absense of Timeliness on Part of NRC Replying to Letters ML20195G9411999-06-10010 June 1999 Informs That Maine Yankee Considers Backfit Claim & Appeal Request of 980716 & 990316,to Be Acceptably Resolved Based on Staff 990518 Response ML20195F7531999-06-0707 June 1999 Forwards Copy of Insurance Endorsement Dtd 990429,reflecting Change in Nuclear Energy Liability Insurance,Iaw Requirements of 10CFR140.15(e) ML20195F6721999-06-0707 June 1999 Forwards Insp Rept 50-309/99-01 on 990214-0513.No Violations Noted.Operations & Radiological Protection Programs, Including Radioactive Liquid & Gaseous Effluent Control Programs,Were Inspected During Insp ML20206U9711999-05-18018 May 1999 Responds to & Addl Info Re Appeal of NRC Determination Re Claim of Backfit Concerning Permanently Shutdown Reactor Security Plan ML20207A2851999-05-14014 May 1999 Informs That NRC Office of Nuclear Reactor Regulation Reorganized Effective 990328.As Part of Reorganization, Division of Licensing Project Mgt Created.Organization Chart Encl ML20206H1391999-05-0505 May 1999 Forwards Amend 164 to License DPR-36 & Safety Evaluation. Amend Consists of Changes to License in Response to 970930 Application ML20206H2311999-05-0404 May 1999 Responds to to Chairman Jackson.Forwards Copy of Recent Staff Response to Petition Submitted on Behalf of Ucs Re Fuel Cladding at Operational Reactors ML20206G5561999-05-0303 May 1999 Forwards Amend 163 to License DPR-36 & Safety Evaluation. Amend Revises Liquid & Gaseous Release Rate Limits to Reflect Revs to 10CFR20, Stds for Protection Against Radiation ML20206J2801999-04-30030 April 1999 Forwards 1998 Annual Financial Repts for CT Light & Power Co,Western Ma Electric Co,Public Svc Co of Nh,North Atlantic Energy Corp,Northeast Nuclear Energy Co & North Atlantic Energy Svc Corp,License Holders ML20206D7191999-04-29029 April 1999 Forwards Listed Radiological Repts for 1998 Submitted IAW Relevant Portions of License DPR-36 & ODCM ML20206E2911999-04-28028 April 1999 Requests NRC Review of ISFSI Licensing Submittals,As Scheduled & ISFSI Approval for Operation by Dec 2000.Util Will Support Any NRC RAI on Expedited Basis.Licensing Milestone Schedule,Encl ML20206E3101999-04-28028 April 1999 Forwards Data Diskette Containing 1998 Individual Monitoring NRC Form 5 Rept,Per 10CFR20.2206(b).Without Diskette ML20206A5521999-04-23023 April 1999 Forwards Environ Assessment & Finding of No Significant Impact Related to Util Application Dtd 980714,for Amend to License DPR-36 to Revise App a TSs to Change Liquid & Gaseous Release Rate Limits to Reflect Revs Made to 10CFR20 ML20206A6871999-04-22022 April 1999 Informs of Completion of Review of Re Nepco in Capacity as Minority Shareholder in Vermont Yankee Nuclear Power Corp,Yaec,Myap & Connecticut Yankee Atomic Power Co ML20205N6211999-04-0707 April 1999 Ack Receipt of Which Appealed NRC Staff Determination That Util Had Not Raised Valid Backfit Claim in to Nrc.Staff Began Process of Convening Backfit Review Panel to Evaluate Appeal ML20205K6541999-04-0707 April 1999 Submits Nuclear Property Insurance Coverage Presently in Force to Protect Maine Yankee at Wiscasset,Me ML20206H2401999-03-30030 March 1999 Informs That Myap Recently Revealed That Approx 20% of Fuel Assemblies Now in SFP Are non-std & Require Special Handling & Dry Cask Packaging.Info Confirms Growing Evidence of Periodic Loss of Radiological Control ML20206A6951999-03-29029 March 1999 Request Confirmation That No NRC Action or Approval,Required Relative to Proposed Change in Upstream Economic Ownership of New England Power Co,Minority Shareholder in Vermont Yankee Nuclear Power Corp,Yaec,Myap & Connecticut Yankee 1999-09-08
[Table view] Category:INCOMING CORRESPONDENCE
MONTHYEARML20217N8371999-10-13013 October 1999 Forwards Summary of Changes Made to Maine Yankee Defueled Security Plan,Iaw 10CFR50.54(p)(2).Without Encl ML20217J0241999-10-13013 October 1999 Documents 991005 Telcon Between NRC & Util to Address All of Areas Identified in Reg Guide 1.179 & NUREG-1700 Re Final Survey Plan Except for One Area ML20212M2431999-09-22022 September 1999 Expresses Concern Re NRC Consideration of Adoption of Policy Based on Requests from Licensees,To Allow as Part of Decommissioning of Nuclear Power Plants & Demolition of Onsite Structures at Reactor Plant Sites ML20212B7011999-09-14014 September 1999 Submits Comments & Raises Questions Re Generation of White Paper for Commission to Decide Merits of Rubberization ML20212E4841999-08-27027 August 1999 Informs That at 990429 Meeting of Myap Community Advisory Panel,R Shadis,Asked If Given Lack of Resident Inspectors & Limited NRC-license Review Correspondence,If Shadis Could Take Part in Weekly NRC Conference Calls with Licensee ML20216F1891999-08-26026 August 1999 Forwards Copies of Maine Yankee & Yankee Rowe Refs Listed, Supporting Industry Position That Branch Technical Position Asb 9-2 Methodology over-estimates Spent Fuel Decay Heat ML20211C0591999-08-19019 August 1999 Forwards Addl Justification for Proprietary Request Re 990809 Submittal Info on Maine Yankee License Termination Plan ML20212A5981999-08-16016 August 1999 Expresses Appreciation for with Respect to e-mail Message Re Site Release Criteria Standards Can Never Be Verified Using Existing Database ML20210Q7201999-08-0909 August 1999 Forwards non-proprietary & Proprietary Draft Documents Re Info on Myap License Termination Plan & Diskette.Proprietary Info & Diskette Withheld ML20211D7041999-08-0909 August 1999 Forwards Rev 17 of Maine Yankee Defueled Safety Analysis Rept (Dsar), Per 10CFR50.71 & 10CFR50.4 ML20212B2271999-08-0606 August 1999 Discusses Concerns Re Recent Incindent Involving Transport of Nuclear Matl from Maine Yankee ML20210M8171999-08-0505 August 1999 Forwards Draft License Termination Plan/Amend Plan for Maine Yankee Atomic Power Co, to Enhance Dialogue Between Various Stakeholders & Provide Springboard for Clarifying Mutual Expectations.With Three Oversize Drawings ML20210L2211999-08-0202 August 1999 Forwards Two Copies of Objectives & Sequence of Events for Maine Yankee Emergency Preparedness Exercise for 990922. Without Encl ML20217M6571999-07-19019 July 1999 Expresses Concern Re Verification of Cleanup Stds at Maine Yankee Atomic Power Co Power Station ML20216D4311999-07-19019 July 1999 Informs That Util Intends to Construct ISFSI Located on Owner Controlled Property Currently Part of Maine Yankee Reactor Site ML20210C6271999-07-15015 July 1999 Forwards Draft Site Characterization Summary in Support of 10CFR50 License Termination & Copy of Latest Decommissioning Schedule with Milestones Identified.Info Submitted Per License Termination Plan ML20210G3981999-06-30030 June 1999 Discusses Review of Ltr Re Maine Yankee Backfit Appeal with Respect to Emergency Plan Exemptions for Decommissioning Plants ML20209C7731999-06-30030 June 1999 Responds to EDO Backfit Appeal Determination Re Emergency Plan Exemptions for Decommissioning Plants ML20209B4611999-06-29029 June 1999 Submits Response to GL 98-01, Y2K Readiness of Computer Sys at Nuclear Power Plants. Plant Is Y2K Ready.Contingency Plans Developed to Mitigate Potential Impact of non-plant Y2K-induced Events ML20195H1741999-06-15015 June 1999 Forwards Original & Copy of Request for Approval of Certain Indirect & Direct Transfer of License & Ownership Interests of Montaup Electric Co (Montaup) with Respect to Nuclear Facilities Described as Listed ML20195G9411999-06-10010 June 1999 Informs That Maine Yankee Considers Backfit Claim & Appeal Request of 980716 & 990316,to Be Acceptably Resolved Based on Staff 990518 Response ML20195F7531999-06-0707 June 1999 Forwards Copy of Insurance Endorsement Dtd 990429,reflecting Change in Nuclear Energy Liability Insurance,Iaw Requirements of 10CFR140.15(e) ML20206J2801999-04-30030 April 1999 Forwards 1998 Annual Financial Repts for CT Light & Power Co,Western Ma Electric Co,Public Svc Co of Nh,North Atlantic Energy Corp,Northeast Nuclear Energy Co & North Atlantic Energy Svc Corp,License Holders ML20206D7191999-04-29029 April 1999 Forwards Listed Radiological Repts for 1998 Submitted IAW Relevant Portions of License DPR-36 & ODCM ML20206E2911999-04-28028 April 1999 Requests NRC Review of ISFSI Licensing Submittals,As Scheduled & ISFSI Approval for Operation by Dec 2000.Util Will Support Any NRC RAI on Expedited Basis.Licensing Milestone Schedule,Encl ML20206E3101999-04-28028 April 1999 Forwards Data Diskette Containing 1998 Individual Monitoring NRC Form 5 Rept,Per 10CFR20.2206(b).Without Diskette ML20205K6541999-04-0707 April 1999 Submits Nuclear Property Insurance Coverage Presently in Force to Protect Maine Yankee at Wiscasset,Me ML20206H2401999-03-30030 March 1999 Informs That Myap Recently Revealed That Approx 20% of Fuel Assemblies Now in SFP Are non-std & Require Special Handling & Dry Cask Packaging.Info Confirms Growing Evidence of Periodic Loss of Radiological Control ML20206A6951999-03-29029 March 1999 Request Confirmation That No NRC Action or Approval,Required Relative to Proposed Change in Upstream Economic Ownership of New England Power Co,Minority Shareholder in Vermont Yankee Nuclear Power Corp,Yaec,Myap & Connecticut Yankee ML20205C3331999-03-24024 March 1999 Submits Rept on Status of Decommissioning Funding for Year Ending 981231.Requested Info Provided in Attachment ML20205B7321999-03-24024 March 1999 Documents Withdrawal of Previously Submitted Request for Exemption from Requirements of 10CFR70.24 Re Criticality Accident Requirements, ML20204E5671999-03-18018 March 1999 Forwards Rev 1 to Maine Yankee Atomic Power Station Security Plan & Description of Changes & Summary of 10CFR50.54(p) Effectiveness Evaluation.Without Encl ML20206K6811999-03-16016 March 1999 Forwards Background & Details Re Backfits Claimed in Util Re Permanently Shutdown Reactor Security Plan ML20205G9841999-01-0505 January 1999 Discusses 1997 Maff - Sepa Radioactivity in Food & Environ ML20197J9001998-12-0707 December 1998 Submits Appeal of DD Re Myap Claim of Backfit Re Beyond Design Basis Accidents in Spent Fuel Pools.Discussion of Licensee Reasons,Provided ML20198J4061998-11-0909 November 1998 Ack Receipt of Roe Response to & Copy of Chairman 981014 address,S-98-25.Informs That Root of NRC Problems Lies in Inability to Create multi-dimensional Vision,Mission or Picture of Future NRC in 2003,2008 or Any Time Frame ML20195E8961998-11-0909 November 1998 Provides Response to Nov, Re NRC Insp Repts 50-309/96-09,50-309/96-10,50-309/96-11,50-309/96-16 & 50-309/97-01.Corrective Actions:Util in Compliance with TS 5.5,which Is Current Ref to Cited TS 5.8.2.a ML20155J0871998-11-0505 November 1998 Forwards Supplemental Info for NRC Review Re TS Change 208 Request on Sf Pool Cooling Sys ML20155H9461998-11-0303 November 1998 Informs That All Future Correspondence Being Sent to Myap Should Be Sent to Listed Address ML20155G9451998-11-0303 November 1998 Forwards Rev 1 to M01-1258-002, Decommissioning Cost Analysis for Myaps, Detailing Study of Decommissioning Costs.Rev 1 to Post-Shutdown Decommissioning Rept, Encl. Info Is Submitted as Required by 10CFR50.82(a)(8)(iii) ML20155D6461998-10-29029 October 1998 Forwards Corrected, Occupational Radiation Exposure Rept for 1997, Including Work & Job Function Categories That Were in Effect in 1997 Under Former TS 5.9.1.3.A.Earlier Submittal Contained Incorrect Info ML20155D7971998-10-28028 October 1998 Forwards Response to NRC 981002 RAI Re Modeling Spent Fuel Pool Heatup.Info Is Needed for NRC to Address Future Exemption Requests from Permanently Shutdown Plants in More Generic & Timely Manner ML20155B7221998-10-26026 October 1998 Informs That Util Has Been Unsuccessful in Determining Status &/Or Estimated Completion Date of NRC Evaluation of Licensee Backfit Claim.Assistance in Resolving Matter, Requested ML20154L4821998-10-15015 October 1998 Forwards Maine Yankee Defueled Emergency Plan. Change to Maine Yankee Emergency Plan Has Been Made in Accordance with 10CFR50.54(q) ML20203H2231998-10-14014 October 1998 FOIA Request for Documents Re EAs 96-299,96-320,96-375, 96-397,97-034,97-147 & 97-559 for Myaps.Requested Documents Include OI Repts & Internal Ltrs,Memos & e-mail Messages to & from OE ML20206N7601998-10-13013 October 1998 Discusses Concerns Re Regulatory Failures at Maine Yankee & Requests NRC Convene Public Meeting Between NRC Staff & Maine Yankee Stakeholders to Discuss Events of Past Two Years ML20203A8291998-09-29029 September 1998 Submits follow-up to Last Week Telcon Request That NRC Meet with Maine Advisory Committee on Radiation on Evening of 991104,to Provide Info & Answer Questions to Committee on Recent Exemptions Granted to Maine Yankee on Emergency Plan ML20153E7541998-09-22022 September 1998 Expresses Disappointment in Quality & Approach of Staff SER, to Provide Comments on Some of Bases Considered in Issuance of Exemption to Allow Util to Discontinue Offsite Emergency Planning Activities.Factual Discrepancies Noted ML20153B2971998-09-17017 September 1998 Withdraws Exemption Request from Certain Insurance Coverage & Financial Protection Requirement Limits of 10CFR50.54(w) & 10CFR140.11.If NRC Disagrees W/Conclusion Contained in Ltr, NRC Should Continue to Process 10CFR140.11 Request ML20155D8331998-08-31031 August 1998 Forwards Public Version of, Maine Yankee Emergency Preparedness Exercise, for Exercise Scheduled for 981028. Rept Demonstrates Major on-site Emergency Response Elements for Defueled & Permanently Defueled Shutdown Plant 1999-09-22
[Table view] |
LER-2097-004, Forwards Comments on Preliminary Accident Sequence Precursor Analysis of Operational Condition Discovered at Myaps on 970122 & Reported in LER 97-004 |
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3092097004R00 - NRC Website |
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MaineYankee MLM((UICM[EIN DSGII
. . 3?9 DATH ROAD
- BRUNSWICK. MAINE 04011 * (207) 79&4100 October 15,1997 MN-97115 JRI197 213 UNITED STATES NUCLEAR REGULATORY COMMISSION Attention: Document Control Desk Washington, DC 20555
References:
(a) License No. DPR 36 (Docket No. 50 309)
(b) Letter: D.ll. Dorman, USNRC to M.it Sellman, MYAPC; Review of Preliminary Accident Scluence Precursor Analysis of Operational Consideration at Maine Yankee Atomic Power Station; dated September 3,1997
Subject:
Review of Preliminary Accident Sequence Precursor Analysis of Operational Condition at Maine Yankee Atomic Power Station Gentlemen:
Reference (b) transmitted for our review and comment the preliminary Accident Sequence Precursor (ASP) analysis of an operational condition which was discovered at the Mainc Yankee Atomic Power Station on January 22,1997 and reported in Licensec Event Report (LER) No. 50 309/004.
Attachment A to this letter delineates our comments. We generally agree that the NRC model is appropriate. We do however have reservations regarding the success criteria and the assumptions which are the elements of the sequence which accounts for almost 100% of the total contribution to the increase in the Core Damage Probability.
Should you have any questions or require additional information, please contact us.
Very truly yours, at-o k. h -
James R. lichett, Manager Regulatory Affairs Department jgl3 attachment c:
Mr. Ilubert Miller Mr. D.11. Dorman Mr. R. A. Rasmussen Mr. Clough Toppan 91
'*]
Mr. P. J. Dostic giglg .[ l
$kkk,k Mr. Uldis Vanan 9710220240 97to15
. DR ADOCK-030003 9.
-- - ~ - - - - -
l Comments on Preliminary Accident Sequence Precursor (Asp) Analysis of Operational Condition Reported in LElt 50-309/97 004 Summary The " analysis results" indicate a Core Damage Probability (CDP) increase of 1.3E-05. A single
" sequence accounts for almost 100% of the total contribution to the increase in the CDP." It is also stated that "There is substantial uncertainty in this estimate because of the uncertainty in the frequency of a large I.OCA (none have occuned) and the likelihood of h10V's failing under post-1.OCA conditions."
In fact this " result" is considerably more uncertain than stated; it is based almost solely on assumptions; it probably represents a significant overestimate of Core Damage Probability, Response to " Guidance for Lictmse Review of Prdiminary ASP Analysis" The guidance provided asks three questions. A brief response to each is provided here with additional discussion following (note that question 3 has been separated into its three pads):
- 1. Does the " Event Description" section accurately describe the event as it occurred?
In general, this section reasonably reflects the LER's event description however two points are unclear:
- i. the event involved identification of the palttitial for thennal pressure locking of certain hiOVs; the discussion makes it clear that hydraube pressure locking did not occur; it is not clear that thennal pressure locking did not occur either.
ii. most importantly, the description states that "lloron precipitation ... could lead to core damage ..."; although this generally reflects LER supplied information, it may lead to inappropriate success criteria for a realistic risk analysh; please see the " success criteria" discussion below.
- 2. Does the " Additional Event-Related Infonnation" section provide accurate additional information ... ?
Yes, but it may be incomplete; please see " additional model related comments" below.
3a. Does the "hiodeling Assumptions" section accurately describe the modeling done for the event?
Yes.
- a 3b. Is the modeling of the event appropriate for the events that occmred or had the potential to occur under the event conditions?
No.
The success criteria appears inappropriate; please see " success criteria" discussion below.
The analysis result is driven almost entirely by assumptions; these assumptions have little, if any, basis; no sensitivity analysis is provided to consider the effect of these assumptions on the results; please see " assumptions" below.
3c. This also includes assumptions regarding the likelihood of equipment recovery.
The analysis unrealistically assumes no credit for any recovery action; please see "acsumptions" below.
StitsnLCrikIia Maine Yankee's design basis accident analysis does require hot leg recirculation within 19 hours2.199074e-4 days <br />0.00528 hours <br />3.141534e-5 weeks <br />7.2295e-6 months <br /> of a large cold leg LOCA. The potential for this not to be provided due to thennal pressure locking of MOVs was reported via the subject LER. The success criteria involved in such design basis analysis is well known to be consenative, oRen very conservative. it is common for probabilistic risk analysis to use alternate, more realistic success criteria. For example, as stated in the subject analysis,"llot-leg recirculation is not addressed in the (Maine Yankee] IPE; however, the LER for this event indicated that the switch-over to hot leg recirculation is required 19 h aner a large cold leg break."
The subject analysis is based on the LER statement which reneets design basis. Such conservative design basis success criteria is inappropriate for use in risk analysis, especially when that analysis is stated to be "as realistic as possible" (September 3,1997 transmittal letter, D. Donnan to M.
Sellman).
While it may be possible to experience some limited, local damage to fuel in the event of boron precipitation following failure of hot leg recirculation, it may be unrealistic to as;ume signincant
" core damage" (in the sense PRAs / IPEs use the tenn). It would seem reasonable to expect, for example, that precipitated boron might go back into solution in the event of core heatup. If more realistic success criteria were considered, rather than reliance on conservative design basis criteria, this analysis might find the CDP contribution to be zero.
Funher discussion related to success criteria "2." on page 3 of the analysis can be found below under
" Additional Model Related Comments".
> e .
Assurnptiom The " analysis results" indicate a Corr, Damage Probability (CDP) increase of 1.3E-05. A single
" sequence accounts for almost 100% of the total contribution to the increase in the CDP."
In addition to the success criteria assumption discussed above, the single sequence is calculated from he following:
Sequence Element Value Source Lmge LOCA frequency 2.7E-04/yr Maine Yankee IPE Fraction of Large LOCAs in 0.5 Assumption Cold Leg Plant Availability 0.7 Not stated (but agrees with IPE value) llot Leg Recirculation Failure 0.1 Assumption Non Recovery Probability 1.0 Assumption The " analysis results" state that "There is substantial uncertainty in this estimate because of the uncertainty in the frequency of a large LOCA (none have occurred) and the likelihood of MOV's failing under post-LOCA conditions."
in fact this " result" is considerably more uncertain than s;ated; it is based almost solely on assumptions.
Additional Model Related Comments Although not significant to this particular analysis:
- a. post-RAS / post-LOCA recirculation cooling, with Containment Spray pumps feeding Charging / IIPSI pumps is train dependent. That is Train A Spray feeds Train A lIPSI only (similar for B). The event tree analysis included appears to consider a "1 out of 2" success criteria for top event "llPSl" and for top event "COLDLEG". It is unclear w hether the train-wise dependence has been modeled. Successful cold leg recirculation requires the same train ofIIPSI and Spray to be operating (cross train alignment is possible with manual recovery action).
- b. Success criteria "2." on page 3 of the subject analysis indicates that Large LOCA can be successfully mitigated with "no llPSI, two LPSI, one accumulator, and successful switch-over to cold leg recirculation." Since cold leg recirculation requires llPSI, it can not be accomplished with "no llPSI". Although this dependence is acknowledged later on page 3 under "HPSl",it is unclear how this is actually modeled, it would appear that sequences 7 through 9 of the event tree (Figure 2, page 7) are impossible; if so, all sequences below 6 i
could be condensed into a single sequence with IIPSI failure leading to "CD".
..-