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| {{Adams|number = ML070390148}} | | {{Adams |
| | | number = ML071000082 |
| | | issue date = 04/10/2007 |
| | | title = Clintion Power Station, Information Requested for NRC Biennial Baseline Component Design Bases Inspection 05000461/07-006 |
| | | author name = Stone A M |
| | | author affiliation = NRC/RGN-III/DNMS |
| | | addressee name = Crane C M |
| | | addressee affiliation = Exelon Generation Co, LLC |
| | | docket = 05000461 |
| | | license number = NPF-062 |
| | | contact person = |
| | | document report number = IR-07-006 |
| | | document type = Letter |
| | | page count = 12 |
| | }} |
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| [[Issue date::February 7, 2007]] | | [[Issue date::April 10, 2007]] |
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| EA-06-291Mr. Christopher M. CranePresident and Chief Nuclear Officer Exelon Nuclear Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555
| | Mr. Christopher M. CranePresident and Chief Nuclear Officer Exelon Nuclear Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 |
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| SUBJECT: FINAL SIGNIFICANCE DETERMINATION FOR A WHITE FINDING AND NOTICE OF VIOLATION; NRC INSPECTION REPORT NO. 05000461/2007006(DRS) FOR CLINTON POWER STATION | | SUBJECT: CLINTON POWER STATION - INFORMATION REQUEST FOR AN NRCBIENNIAL BASELINE COMPONENT DESIGN BASES INSPECTION 05000461/2007006(DRS) |
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| ==Dear Mr. Crane:== | | ==Dear Mr. Crane:== |
| The purpose of this letter is to provide you the final results of our significance determination of the preliminary Greater Than Green finding identified in Inspection Report No. 05000461/
| | On October 15, 2007, the NRC will begin a biennial baseline Component Design BasesInspection (CDBI) at the Clinton Power Station. This inspection will be performed in accordance with revised NRC Baseline Inspection Procedure (IP) 71111.21 and replaces the biennial Safety System Design and Performance Capability Inspection. The CDBI inspection focuses on components which have high risk and low design margins. The components to be reviewed during this baseline inspection will be identified during an in-office preparation week prior to the first week of the onsite inspection. In addition, a number of risk significant operator actions and operating experience issues, associated with the component samples, will also be selected for review. The inspection will include three weeks onsite, including the information gathering during thefirst onsite week. The inspection team will consist of six NRC inspectors, of whom five willfocus on engineering and one on operations. The current inspection schedule is as follows: *October 15 through October 19, 2007;*October 29 through November 2, 2007; and |
| 2006011(DRS). The inspection finding was assessed using the Significance Determination Process and was preliminarily characterized as Greater Than Green, a finding of greater than very low safety significance, resulting in the need for further evaluation to determine significance; and therefore, the need for additional NRC action. This Greater Than Green finding involved the failure to select an appropriate method for calculating the minimum elevation (i.e., the analytical level) of water above the high pressure core spray (HPCS) pump suction line to preclude vortex formation and subsequent air entrainment in the pump's suction. As a result, the analytical level would result in significant air entrainment potentially causing the HPCS to be incapable of completing its safety function. At our request, a Regulatory Conference was held on December 19, 2006, to further discussyour views on this issue. The public meeting summary, including the handouts, can be found in the Agencywide Document Access and Management System (ADAMS) ML063520445. During the meeting, your staff described the results of recent scaled model testing. Specifically, the scaled model testing showed that a localized depression briefly formed which immediately collapsed and resulted in significant (about 24 percent) air being entrained in the suction piping. You determined that this air/water mixture would result in a slowed level decrease in the reactor core isolation cooling tank resulting in a delay in transferring suction to the suppression pool. However, your calculations showed that the suction valve from the suppression pool wouldopen and suction would be primarily from the suppression pool prior to the air reaching the suction of the HPCS pump. Therefore, you concluded that the HPCS pump would be capable of performing its safety function. In assessing the test model results, you assumed that flow C. Crane-2-would not be characterized as slug flow, that is, the flow would be less than 24 percent airentrained. Your conclusion was based on: (1) visual confirmation during Alden Laboratory Testing; (2) visual comparison of test results against a "known" flow having 24 percent air entrainment; and (3) a computer model (RELAP) prediction that slug flow would exist above 24 percent. The NRC identified the following concerns with your conclusion: *During testing at Alden Laboratory, the pump was stopped immediately (about 5 seconds) upon visual observation of 'break through', i.e., air becoming entrained in the suction pipe. This was done to preserve and prevent damage to the test pump.
| | *November 12 through November 16, 2007.The team will be preparing for the inspection, mainly during the week of October 8, 2007, asdiscussed in the attached enclosure. A Region III Senior Reactor Analyst may accompany theinspection team during the week of October 15, 2007, to review probabilistic risk assessment data and assist in identifying risk significant components, which will be reviewed during the inspection.Experience with previous baseline design inspections of similar depth and length has shownthat these type of inspections are extremely resource intensive, both for the NRC inspectors and the licensee staff. In order to minimize the inspection impact on the site and to ensure a productive inspection for both parties, we have enclosed a request for information needed for the inspection. |
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| This quick stopping did not allow time to verify the absence of slug flow.*The visual comparison of the test results against a "known" flow having 24 percent airentrainment was short in duration. This visual comparison may not represent actual test or in-plant flow conditions. With flow and flow conditions unstable and oscillating, this short time duration did not provide definitive proof that slug flow would not exist. Actual void fraction measurements may typically have as much as 8 percent uncertainty.*The computer model (RELAP) is a generic 2-phase flow code and is not necessarilytuned or calibrated to this exact scenario. To consider results 'exact' and without any consideration of analytical error is imprudent. The assumption of 24 percent air entrainment was key in assessing the ability of HPCS toperform its function for several reasons. First, the 24 percent provides a basis for the rate of decrease in the RCIC tank. A greater void fraction would slow down the rate of change, increasing the time to the swap-over point. This increase in time, would allow the air wave front to travel further down the line and potentially reach pump suction prior to full opening of the suppression pool suction valve. Secondly, although your staff calculated a 2-phase fluid flowvelocity, an increase in void fraction will increase the transport velocity, increasing the possibility of air arrival at the pump. Lastly, should slug flow exist, there is a potential for system waterhammer affecting system piping or the HPCS pump or both.In summary, the staff does not concur with your evaluation regarding the amount of airentrainment; and therefore, does not agree with your assessment on the past operability of the HPCS pump. Your assessment is not conclusive, complete or robust, in that the basis for 24 percent was not well founded. Small changes to these assumptions may significantly impact the conclusion regarding past HPCS pump operability. In addition, during the Regulatory Conference, you also provided your assessment of thesignificance of the finding. Specifically, you provided information regarding the potential for operators to throttle HPCS flow and the estimated contribution to the risk from fire events. The NRC reviewed the information regarding throttling the HPCS injection valve and determined C. Crane-3-that it should be considered in the final significance determination. Based on the discussion atthe Regulatory Conference, operators would be directed to throttle HPCS in response to transient (i.e., non- Loss of Coolant Accidents and non- Anticipated Transient Without a Scram)
| | C. Crane-2-It is important that all of these documents are up to date and complete in order to minimize thenumber of additional documents requested during the preparation and/or the onsite portions of the inspection. Insofar as possible, this information should be provided electronically to the lead inspector. The information request has been divided into three groups:*The first group lists information necessary for our initial inspection scoping activities. This information should be available to the lead inspector no later than September 17, 2007. By September 28, the lead inspector will communicate the initial selected set of approximately 30 high risk components. *The second group of documents requested are those items needed to support ourin-office preparation activities. This set of documents, including the calculations associated with the initial selected components, should be available at the Regional Office no later than October 5, 2007. During the in-office preparation activities, the team may identify additional information needed to support the inspection. *The last group includes the additional information above as well as plant specificreference material. This information should be available to the team on the first day of the inspection. It is also requested that corrective action documents and questions developed during the inspection be provided to the inspectors throughout the inspection.The lead inspector for this inspection is Mr. Zelig Falevits. We understand that our licensingcontact for this inspection is Mr. R. Frantz of your organization. If there are any questions about the inspection or the material requested in the enclosure, please contact the lead inspector at (630) 829-9717 or via e-mail at ZXF@nrc.gov.In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter andits enclosure will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records (PARS) component of NRC's document system (ADAMS), accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html (thePublic Electronic Reading Room). |
| scenarios. If operators successfully throttle the HPCS injection valve, the system flow rate will be low enough that air entrainment during suction swap-over to the suppression pool would no longer be a concern. For the final significance determination, the NRC assumed that HPCS would fail in response to transient initiating events only if the operator failed to properly throttle the HPCS injection valve. For all other initiating events, HPCS was assumed to fail during the suction transfer, consistent with the assumption in the preliminary significance determination. Given the inherent uncertainty in estimating human error probabilities, the NRC used its best estimate of 2.6E-2 for the human error probability in the final significance determination.The NRC also reviewed the estimation of fire risk contribution that you provided and determinedthat it was the best available information; and therefore, it was used directly in the final significance determination.After considering the information presented at the Regulatory Conference and the additionalinformation you provided in your letter dated December 21, 2006, the NRC has concluded that the inspection finding is appropriately characterized as White, an issue with low to moderate increased importance to safety, which may require additional NRC inspections. Using the estimation of fire risk contribution and best estimate for human error probability, the NRC determined the total change in core damage frequency to be about 4.4E-6 per year. You have 30 calendar days from the date of this letter to appeal the staff's determination ofsignificance for the identified White finding. Such appeals will be considered to have merit only if they meet the criteria given in NRC Inspection Manual Chapter 0609, Attachment 2.The NRC has also determined that the failure to ensure the adequacy of design of the HPCSsystem by performance of design reviews or by use of alternate or simplified calculational methods is a violation of Title 10 Part 50, Appendix B, Criteria III, as cited in the enclosedNotice of Violation (Notice). The circumstances surrounding the violation are described in detailin Inspection Report No. 05000461/2006011(DRS). In accordance with the NRC Enforcement Policy, NUREG-1600, the Notice of Violation is considered escalated enforcement action because it is associated with a White finding.You are required to respond to this letter and should follow the instructions specified in theenclosed Notice when preparing your response.Because plant performance for this issue has been determined to be in the regulatory responseband, we will use the NRC Action Matrix, to determine the most appropriate NRC response for this event. We will notify you, by separate correspondence, of that determination.
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| C. Crane-4-In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter, itsenclosure and response will be made available electronically for public inspection in the NRC Public Document Room or from the Publically Available Records (PARS) component of NRC's document system (ADAMS), accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).
| | Sincerely,/RA/Ann Marie Stone, ChiefEngineering Branch 2 Division of Reactor Safety Docket No. 50-461License No. NPF-62 |
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| Sincerely,/RA/James L. CaldwellRegional AdministratorDocket No. 50-461License No. NPF-62 | |
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| ===Enclosure:=== | | ===Enclosure:=== |
| Notice of Violationcc w/encl:Site Vice President - Clinton Power StationPlant Manager - Clinton Power Station Regulatory Assurance Manager - Clinton Power Station Chief Operating Officer Senior Vice President - Nuclear Services Vice President - Operations Support Vice President - Licensing and Regulatory Affairs Manager Licensing - Clinton Power Station Senior Counsel, Nuclear, Mid-West Regional Operating Group Document Control Desk - Licensing Assistant Attorney General Illinois Emergency Management Agency State Liaison Officer, State of Illinois Chairman, Illinois Commerce Commission 1 HQ concurrence received via e-mail from D. Starkey, OE on February 2, 2007
| | Component Design Bases Inspection Document Request See Attached Distribution |
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Category:Letter
MONTHYEARML24222A6772024-08-0909 August 2024 Response to Request for Additional Information for Application to Revise Technical Specifications to Adopt TSTF-591-A, “Revise Risk Informed Completion Time (RICT) Program” Revision 0 and Revise 10 CFR 50.69 License Condition IR 05000461/20240022024-08-0909 August 2024 Integrated Inspection Report 05000461/2024002 ML24220A2772024-08-0707 August 2024 Request for Information for the NRC Quadrennial Comprehensive Engineering Team Inspection: Inspection Report 05000461/2025010 ML24212A2212024-08-0202 August 2024 License Renewal Regulatory Audit Regarding the Environmental Review of the License Renewal Application (EPID Number: L-2024-LNE-0000) (Docket Number: 50-461) ML24157A3242024-07-11011 July 2024 Issuance of Amendment No. 254 Revision of Reactor Water Cleanup Isolation Valve Timing ML24158A0772024-07-0303 July 2024 Notice of Consideration of Approval of Partial Site Release, Public Meeting, and Request for Comments (EPID L-2023-LLA-0088) - Letter ML24163A3252024-06-28028 June 2024 Aging Management Regulatory Audit Plan ML24163A3242024-06-28028 June 2024 LRA - Portal Letter ML24179A3112024-06-27027 June 2024 05000461; Notification of an NRC Biennial Licensed Operator Requalification Program Inspection and Request for Information ML24176A0272024-06-25025 June 2024 Confirmation of Initial License Examination, July 2025 RS-24-061, Constellation Energy Generation, LLC, Response to NRC Regulatory Issue Summary 2024-01, Preparation and Scheduling of Operator Licensing Examinations2024-06-14014 June 2024 Constellation Energy Generation, LLC, Response to NRC Regulatory Issue Summary 2024-01, Preparation and Scheduling of Operator Licensing Examinations ML24142A3352024-05-21021 May 2024 Quad Cities—Information Request to Support the NRC Annual Baseline Emergency Action Level and Emergency Plan Changes IR 05000461/20240122024-05-20020 May 2024 Biennial Problem Identification and Resolution Inspection Report Report 05000461/2024012 RS-24-055, 2023 Corporate Regulatory Commitment Change Summary Report2024-05-17017 May 2024 2023 Corporate Regulatory Commitment Change Summary Report RS-24-050, Additional Information Supporting Request for License Amendment to Revise Technical Specifications Related to Reactor Water Cleanup Isolation Instrumentation2024-05-0909 May 2024 Additional Information Supporting Request for License Amendment to Revise Technical Specifications Related to Reactor Water Cleanup Isolation Instrumentation IR 05000461/20240012024-05-0707 May 2024 Integrated Inspection Report 05000461/2024001 ML24103A1032024-05-0101 May 2024 Shpo Consultation Letter for Clinton License Renewal ML24120A3452024-04-30030 April 2024 Ltr. to Lester Randell, Chairman, Kickapoo Tribe of Indians of the Kickapoo Reservation in Kansas; Re., CPS Section 106 Consultation RS-24-041, Alternative Request to Utilize Code Case OMN-32, Alternative Requirements for Range and Accuracy of Pressure, Flow, and Differential Pressure Instruments Used in Pump Tests2024-04-30030 April 2024 Alternative Request to Utilize Code Case OMN-32, Alternative Requirements for Range and Accuracy of Pressure, Flow, and Differential Pressure Instruments Used in Pump Tests ML24103A1152024-04-30030 April 2024 Ltr. to Geoffrey Standing Bear, Principal Chief, the Osage Nation; Re., CPS Section 106 Consultation ML24120A3462024-04-30030 April 2024 Ltr. to Douglas Lankford, Chief, Miami Tribe of Oklahoma; Re., CPS Section 106 Consultation ML24103A0992024-04-30030 April 2024 Achp Scoping Letter for Clinton License Renewal ML24120A3442024-04-30030 April 2024 Ltr. to Gena Kakkak, Chairman, Menominee Indian Tribe of Wisconsin; Re., CPS Section 106 Consultation ML24120A3432024-04-30030 April 2024 Ltr. to Darwin Kaskaske, Chairman, Kickapoo Tribe of Oklahoma; Re., CPS Section 106 Consultation ML24107B0312024-04-29029 April 2024 Notice of Intent to Prepare an Environmental Impact Statement and Conduct Scoping Process ML24103A2042024-04-12012 April 2024 Constellation Energy Generation, LLC, Application to Revise Technical Specifications to Adopt TSTF-591-A, Revise Risk Informed Completion Time (RICT) Program Revision 0 and Revise 10 CFR 50.69 License Condition ML24089A2222024-04-11011 April 2024 LRA - Acceptance and Opportunity for Hearing - Letter ML24092A3552024-04-0101 April 2024 Request for Information for NRC License Renewal Inspection: Inspection Report 05000461/2024010 RS-24-002, Constellation Energy Generation, LLC - Annual Property Insurance Status Report2024-04-0101 April 2024 Constellation Energy Generation, LLC - Annual Property Insurance Status Report RS-24-031, Updated Safety Analysis Report (Usar), Revision 232024-04-0101 April 2024 Updated Safety Analysis Report (Usar), Revision 23 RS-24-023, Report on Status of Decommissioning Funding.2024-03-22022 March 2024 Report on Status of Decommissioning Funding. IR 05000461/20230042024-02-0202 February 2024 Integrated Inspection Report 05000461/2023004 ML23361A1572024-01-24024 January 2024 Audit Plan in Support of Review of License Amendment Request Regarding Revision of Technical Specifications Related to Reactor Water Cleanup Isolation ML24004A0792024-01-18018 January 2024 Exemption from Select Requirements of 10 CFR Part 73 (EPID L-2023-LLE-0041 (Security Notifications, Reports, and Recordkeeping and Suspicious Activity Reporting)) IR 05000461/20234022023-12-27027 December 2023 Security Baseline Inspection Report 05000461/2023402 ML23305A1402023-12-13013 December 2023 Units 1 & 2; Nine Mile Point, Unit 2; Peach Bottom, Units 2 & 3; and Quad Cities, Units 1 and 2 - Issuance of Amendments to Adopt Traveler TSTF-580 IR 05000461/20235012023-12-0505 December 2023 Emergency Preparedness Biennial Exercise Inspection Report 05000461/2023501 ML23284A2512023-11-22022 November 2023 Amendment No. 250 to Adopt TSTF-332 ML23317A1192023-11-10010 November 2023 Constellation Energy Generation, LLC - 2023 Annual Report - Guarantees of Payment of Deferred Premiums IR 05000461/20230032023-11-0808 November 2023 Integrated Inspection Report 05000461/2023003 ML22300A2212023-11-0202 November 2023 Preliminary Decommissioning Cost Estimate and Fuel Management Plan RS-23-097, Constellation Energy Generation, LLC, Advisement of Leadership Changes and Submittal of Updated Standard Practice Procedures Plans2023-10-12012 October 2023 Constellation Energy Generation, LLC, Advisement of Leadership Changes and Submittal of Updated Standard Practice Procedures Plans IR 05000461/20233012023-09-12012 September 2023 NRC Initial License Examination Report 05000461/2023301 RS-23-090, Annual Report of Emergency Core Cooling System Evaluation Model Changes and Errors for Clinton Power Station2023-09-0707 September 2023 Annual Report of Emergency Core Cooling System Evaluation Model Changes and Errors for Clinton Power Station RS-23-080, Constellation Energy Generation, LLC, Application to Revise Technical Specifications to Adopt TSTF-264-A, Revision 0, 3.3.9 and 3.3.10 - Delete Flux Monitors Specific Overlap Requirement SRs2023-08-30030 August 2023 Constellation Energy Generation, LLC, Application to Revise Technical Specifications to Adopt TSTF-264-A, Revision 0, 3.3.9 and 3.3.10 - Delete Flux Monitors Specific Overlap Requirement SRs IR 05000461/20234202023-08-29029 August 2023 Security Baseline Inspection Report 05000461/2023420 RS-23-081, Request for License Amendment to Revise Technical Specifications Related to Reactor Water Cleanup Isolation Instrumentation2023-08-21021 August 2023 Request for License Amendment to Revise Technical Specifications Related to Reactor Water Cleanup Isolation Instrumentation IR 05000461/20230022023-08-0404 August 2023 Integrated Inspection Report 05000461/2023002 RS-23-085, Supplemental Information Related to Request for Partial Site Release2023-08-0303 August 2023 Supplemental Information Related to Request for Partial Site Release ML23209A8102023-07-28028 July 2023 05000461; Notification of an NRC Biennial Licensed Operator Requalification Program Inspection and Request for Information 2024-08-09
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Inspection Report - Clinton - 2007006 |
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April 10, 2007
Mr. Christopher M. CranePresident and Chief Nuclear Officer Exelon Nuclear Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555
SUBJECT: CLINTON POWER STATION - INFORMATION REQUEST FOR AN NRCBIENNIAL BASELINE COMPONENT DESIGN BASES INSPECTION 05000461/2007006(DRS)
Dear Mr. Crane:
On October 15, 2007, the NRC will begin a biennial baseline Component Design BasesInspection (CDBI) at the Clinton Power Station. This inspection will be performed in accordance with revised NRC Baseline Inspection Procedure (IP) 71111.21 and replaces the biennial Safety System Design and Performance Capability Inspection. The CDBI inspection focuses on components which have high risk and low design margins. The components to be reviewed during this baseline inspection will be identified during an in-office preparation week prior to the first week of the onsite inspection. In addition, a number of risk significant operator actions and operating experience issues, associated with the component samples, will also be selected for review. The inspection will include three weeks onsite, including the information gathering during thefirst onsite week. The inspection team will consist of six NRC inspectors, of whom five willfocus on engineering and one on operations. The current inspection schedule is as follows: *October 15 through October 19, 2007;*October 29 through November 2, 2007; and
- November 12 through November 16, 2007.The team will be preparing for the inspection, mainly during the week of October 8, 2007, asdiscussed in the attached enclosure. A Region III Senior Reactor Analyst may accompany theinspection team during the week of October 15, 2007, to review probabilistic risk assessment data and assist in identifying risk significant components, which will be reviewed during the inspection.Experience with previous baseline design inspections of similar depth and length has shownthat these type of inspections are extremely resource intensive, both for the NRC inspectors and the licensee staff. In order to minimize the inspection impact on the site and to ensure a productive inspection for both parties, we have enclosed a request for information needed for the inspection.
C. Crane-2-It is important that all of these documents are up to date and complete in order to minimize thenumber of additional documents requested during the preparation and/or the onsite portions of the inspection. Insofar as possible, this information should be provided electronically to the lead inspector. The information request has been divided into three groups:*The first group lists information necessary for our initial inspection scoping activities. This information should be available to the lead inspector no later than September 17, 2007. By September 28, the lead inspector will communicate the initial selected set of approximately 30 high risk components. *The second group of documents requested are those items needed to support ourin-office preparation activities. This set of documents, including the calculations associated with the initial selected components, should be available at the Regional Office no later than October 5, 2007. During the in-office preparation activities, the team may identify additional information needed to support the inspection. *The last group includes the additional information above as well as plant specificreference material. This information should be available to the team on the first day of the inspection. It is also requested that corrective action documents and questions developed during the inspection be provided to the inspectors throughout the inspection.The lead inspector for this inspection is Mr. Zelig Falevits. We understand that our licensingcontact for this inspection is Mr. R. Frantz of your organization. If there are any questions about the inspection or the material requested in the enclosure, please contact the lead inspector at (630) 829-9717 or via e-mail at ZXF@nrc.gov.In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter andits enclosure will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records (PARS) component of NRC's document system (ADAMS), accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html (thePublic Electronic Reading Room).
Sincerely,/RA/Ann Marie Stone, ChiefEngineering Branch 2 Division of Reactor Safety Docket No. 50-461License No. NPF-62
Enclosure:
Component Design Bases Inspection Document Request See Attached Distribution