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MONTHYEARML22207A0492022-07-25025 July 2022 Information Request, Security IR 2022402 NLS2021035, Attachment/Enclosureport of Change and Summary of 50.54(q) Analysis - On-Shift Staffing Analysis, Rev. 32021-05-10010 May 2021 Attachment/Enclosureport of Change and Summary of 50.54(q) Analysis - On-Shift Staffing Analysis, Rev. 3 NLS2016063, Enclosure 2: Response to Areas of Requested Information in Appendix a of Generic Letter 2016-01, Monitoring of Neutron-Absorbing Materials in Spent Fuel Pools (Non-Proprietary Version)2016-10-27027 October 2016 Enclosure 2: Response to Areas of Requested Information in Appendix a of Generic Letter 2016-01, Monitoring of Neutron-Absorbing Materials in Spent Fuel Pools (Non-Proprietary Version) ML16125A5222016-05-0404 May 2016 FOIA/PA-2016-0455 - Resp 1 - Final, Agency Records Subject to the Request Are Enclosed ML15014A1602015-01-14014 January 2015 Attachment 2 - NRC Working Group Recommendations to Revise the Substantive Cross-Cutting Issue Process ML15014A1532015-01-14014 January 2015 Attachment 1- NEI Comments on NRC Working Group Recommendations to Revise the Substantive Cross-Cutting Issue Process ML13143A3312013-06-0606 June 2013 Operating Boiling-Water Reactor Licensees with Mark 1 and Mark 2 Containments Addresses List - Enclosure 2 ML12056A0522012-03-12012 March 2012 Enclosure 6 - List of Power Reactor Licensees and Holders of Construction Permits in Active or Deferred Status ML1003306012010-02-0808 February 2010 Compression Test of Concrete, 4000 Psi ML0933507512010-01-14014 January 2010 Temporary Instruction 2515/180, Managing Fatigue ML1003413132010-01-0808 January 2010 Compression Test of Concrete, 3000 Psi ML0911802472009-03-0909 March 2009 Enclosure 5 - FAQ Log ML0921105892009-03-0606 March 2009 Nebraska Game and Parks Commission Species by County List ML0917606542008-04-0404 April 2008 CNS Lr - Air Pollutants and Control Techniques - Particulate Matter, Control Techniques, EPA ML0917501832008-02-15015 February 2008 Lr - NPPD Statement on Addressing Climate Change ML0732400242007-10-25025 October 2007 Examples of Max Thermal Power License Conditions ML0721104332007-07-25025 July 2007 Questions from 1 Through 8 ML0628602342006-10-11011 October 2006 SERP Worksheet for SDP-Related Finding at Cooper Nuclear Station, Service Water Gland Seal Water Configuration Deficiency ML0628602412006-10-11011 October 2006 Analysis: Brief Description of Issue ML0628602402006-10-11011 October 2006 Analysis: Briefing Description of Issue ML0628602292006-10-11011 October 2006 Analysis: Brief Description of Issue ML0628300792006-10-0606 October 2006 Release Severity and Timing Classification Scheme (Severity, Timing) ML0627101442006-09-25025 September 2006 Violations (Violations Are Severity Level IV Unless Otherwise Stated) ML0623601172006-08-22022 August 2006 Identification and Resolution of Problems - SW System Alignment ML0623601262006-08-22022 August 2006 Loop Category ML0623601232006-08-22022 August 2006 Danger Will Robinson: If You Change Cell Locations You May Break the VB Code! ML0623601192006-08-22022 August 2006 Potential Risk Contribution from Large Early Release Frequency (LERF) ML0622205612006-08-0909 August 2006 SDP Phase 1 Screening Worksheet for IE, Ms, and B Cornerstones ML0622204842006-08-0909 August 2006 Undated Paper, Page 8, Table 2 ML0622204962006-08-0909 August 2006 Preliminary Risk Screening for Cooper Service Water Issues ML0622205002006-08-0909 August 2006 Danger Will Robinson: If You Change Cell Locations You May Break the V ML0622205442006-08-0909 August 2006 State the Performance Deficiency Exactly as Stated ML0618607002006-07-0303 July 2006 Enclosure - Final Significance Determination Cooper Nuclear Station, Service Water Gland Seal Water Configuration Deficiency ML0601805372005-06-27027 June 2005 CNS - 06-2005 - Initial Examination Written Reference Handout ML0628602152004-12-0202 December 2004 SERP Worksheet for DP-Related Finding at Cooper Nuclear Station, Service Water Gland Seal Water Configuration Deficiency ML0628601972004-11-30030 November 2004 E-Mail from Sanborn to Allen Et Al., Agenda for Region IV Serp'S on Thurs., Dec. 2, Outside Scope ML0628601862004-10-20020 October 2004 SERP Worksheet for SDP-Related Finding at Cooper Nuclear Station, Service Water Gland Seal Water Configuration Deficiency ML0619802422004-10-18018 October 2004 NRC Question B and CNS Answer ML0619802352004-10-18018 October 2004 NRC Question a and CNS Answer ML0619802282004-09-22022 September 2004 Condition Report CR-CNS-2004-06422, Alarm Procedure Errors ML0619404202004-09-21021 September 2004 CNS Answers to NRC Questions ML0623602872004-08-25025 August 2004 Memo from R. A. Gramm (NRR) to T. A. Bergman (Oedo), Subj: G20040484, Re-Issued Briefing Package for Drop-In Visit on September 2, 2004 by Nebraska Public Power District (NPPD) Officials... ML0628601042004-07-15015 July 2004 SERP Worksheet for SDP-Related Finding at Cooper Nuclear Station, Service Water Gland Seal Water Configuration Deficiency ML0628601052004-07-15015 July 2004 SERP Worksheet for SDP-Related Finding at Cooper Nuclear Station, Service Water Gland Seal Water Configuration Deficiency ML0628601062004-07-15015 July 2004 SERP Worksheet for SDP-Related Finding at Cooper Nuclear Station, Service Water Gland Seal Water Configuration Deficiency ML0628601092004-07-15015 July 2004 SERP Worksheet for SDP-Related Finding at Cooper Nuclear Station, Service Water Gland Seal Water Configuration Deficiency ML0619404382001-12-26026 December 2001 CNS Notification 10132527 ML0619403082001-06-12012 June 2001 CNS Surveillance Data Sheets - Procedure 7.3.1.11, Revision 3 2022-07-25
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Preliminary Risk Screening For Cooper Service Water Issues Background Several service water issues were identified near the end of the Cooper refueling outage. The issues involve pump shaft failures, potential icing of the system, and air introduction from the gland seal cooling water system.Assumptions The issue involving air saturated water from the gland seal system occurred late in the outage.The issue only impacted pumps which were in a standby condition.
Provided the pumps are started periodically (every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) the potential for the standby pump to experience an on-demand failure was minimized.
Two service water pumps, in opposite trains, were always in service. Therefore, the failure due to air accumulation only affected the standby pumps which were located in opposite trains.The impact of potential icing of the service water system did not appear likely. No information was provided which would indicate that either the suction screens or the pump discharge strainer were obstructed due to ice formation.
Therefore, the common cause failure of all service water pumps due to icing was not likely.The pump shaft failure was due to a combination of pre-existing flaws and inadequate pump clearances.
An analysis of the significance of this condition was not completed given the successful operation of the pumps during the previous operating cycle. Common cause failure of the pumps was possible given the overhaul of each service water pump during the outage.However, the duration following the maintenance activity was relatively short and there was very low decay heat. Additionally, no information was provided to suggest that a current common cause failure mechanism exited.Analysis The licensee did not model combinations of 2 and 3 service water pump failures.Consequently, the licensee developed special cases to evaluate the risk significance associated with the various combinations.
The licensee's results were qualitatively compared to the results associated with single pump failures and the common cause failure of all four service water pumps. Based on the comparison, the licensee's results appeared to be reasonable.
The following table illustrates the number of days necessary to reach a delta CDF of 1 E-6/yr.The results were obtained using the zero maintenance PRA model and assumed the condition existed for 1 year of full power operation.
The combinations of concern involve two opposite train service water pumps and the failure of a single pump. Because of the information received to date, the combinations of 3 and 4 service water pumps failing were not considered credible.
Nevertheless, the data is provided in the event additional information becomes available which suggests the likelihood of 3 or 4 service water pumps failing has increased.
The variance in the duration for the pump combinations is due to the design of the service water system.F-05 i Pumps Unavailable Days to 1 E-6lyr SWS A SWS B SWS C SWS D X 150 X 342 X 150 X 342 X X 102 X X 4 X X 102 X X 102 X X 8 X X 102 X X X 3 x X X 5 X X X 3 X X X 5 X X X X 0.7 Because the plant was shutdown or at low power, the actual number of days before reaching 1 E-6/yr would be much greater. Therefore, it is unlikely that the condition would have exceeded the 1 E-6/yr CCDP threshold due to the relatively short duration, the low decay heat, and the number of potentially affected service water pumps.