|
|
| (4 intermediate revisions by the same user not shown) |
| Line 2: |
Line 2: |
| | number = ML103280398 | | | number = ML103280398 |
| | issue date = 12/14/2010 | | | issue date = 12/14/2010 |
| | title = Prairie Island Nuclear Generating Plant, Units 1 and 2, RAI, Related to Request to Exclude the Dynamic Effects Associated with Certain Postulated Pipe Ruptures from the Licensing Basis Based Upon Application of LBB Methodology | | | title = RAI, Related to Request to Exclude the Dynamic Effects Associated with Certain Postulated Pipe Ruptures from the Licensing Basis Based Upon Application of LBB Methodology |
| | author name = Wengert T J | | | author name = Wengert T |
| | author affiliation = NRC/NRR/DORL/LPLIII-1 | | | author affiliation = NRC/NRR/DORL/LPLIII-1 |
| | addressee name = Schimmel M A | | | addressee name = Schimmel M |
| | addressee affiliation = Northern States Power Co | | | addressee affiliation = Northern States Power Co |
| | docket = 05000282, 05000306 | | | docket = 05000282, 05000306 |
| Line 18: |
Line 18: |
|
| |
|
| =Text= | | =Text= |
| {{#Wiki_filter:UNITED NUCLEAR REGULATORY WASHINGTON, D.C. 20555*0001 December 14, 2010 Mr. Mark A. Schimmel Site Vice President Prairie Island Nuclear Generating Plant Northern States Power Company -Minnesota 1717 Wakonade Drive East Welch, MN 55089-9642 PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 REQUEST FOR ADDITIONAL INFORMATION RELATED TO REQUEST TO EXCLUDE THE DYNAMIC EFFECTS ASSOCIATED WITH CERTAIN POSTULATED PIPE RUPTURES FROM THE LICENSING BASIS BASED UPON APPLICATION OF LEAK-BEFORE-BREAK METHODOLOGY (TAC NOS. | | {{#Wiki_filter:UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 December 14, 2010 Mr. Mark A. Schimmel Site Vice President Prairie Island Nuclear Generating Plant Northern States Power Company - Minnesota 1717 Wakonade Drive East Welch, MN 55089-9642 SUB~IECT: PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 REQUEST FOR ADDITIONAL INFORMATION RELATED TO REQUEST TO EXCLUDE THE DYNAMIC EFFECTS ASSOCIATED WITH CERTAIN POSTULATED PIPE RUPTURES FROM THE LICENSING BASIS BASED UPON APPLICATION OF LEAK-BEFORE-BREAK METHODOLOGY (TAC NOS. |
| ME2976 AND ME2977) | | ME2976 AND ME2977) |
|
| |
|
| ==Dear Mr. Schimmel:== | | ==Dear Mr. Schimmel:== |
| By letter to the U.S.
| |
| Nuclear Regulatory Commission (NRC) dated December 22, 2009 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML 100200129) as supplemented by letters dated July 23,2010 (ADAMS Accession No. ML 102040612), August 20, 2010 (ADAMS Accession No. ML 102320535) and October 8, 2010 (ADAMS Accession No. ML 102810518), Northern States Power Company, a Minnesota corporation (the licensee), doing business as Xcel Energy, submitted a request for approval to exclude certain postulated pipe ruptures from the licensing basis based upon application of the leak-before-break methodology for Prairie Island Nuclear Generating Plant, Units 1 and 2. The NRC staff is reviewing your submittal and supplements and has determined that additional information is required to complete the review. The specific information requested is addressed in the enclosure to this letter. During a discussion with Mr. Sam Chesnutt of your staff on November 19, 2010, it was agreed that you would provide a response to this request by December 22, 2010. The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for staff review and contribute toward the NRC's goal of efficient and effective use of staff resources.
| |
| M. Schimmel -2 If circumstances result in the need to revise the requested response date, please contact me at (301) 415-4037.
| |
| Sincerely, Thomas J. Wengert, Senior Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-282 and 50-306 Request for Additional cc w/encl:
| |
| Distribution via REQUEST FOR ADDITIONAL INFORMATION PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 DOCKET NOS. 50-282 AND 50-306 In reviewing the Northern States Power Company, a Minnesota corporation (NSPM, the licensee), doing business as Xcel Energy, submittal dated December 22,2009 (Agencywide Documents Access and Management System (ADAMS)
| |
| Accession No. ML 100200129), as supplemented by letters dated July 23,2010 (ADAMS Accession No. ML 102040612), August 20, 2010 (ADAMS Accession No. ML102320535), and October 8, 2010 (ADAMS Accession No. ML 102810518), which requested approval to exclude certain postulated pipe ruptures from the licensing basis based upon application of the leak-before-break (LBB) methodology for Prairie Island Nuclear Generating Plant (PINGP), Units 1 and 2 (Reference 1), the U.S. Nuclear Regulatory Commission (NRC) staff has determined that additional information is needed to complete its review. In its October 8,2010, supplement, the licensee responded to the NRC staff request for additional information (RAI) regarding the reactor coolant system (RCS) leakage detection systems at PINGP. The
| |
| !\IRC staff has the following clarification questions regarding this RAI response: Regulatory Guide (RG) 1.45 states that "...plants should use multiple, diverse and redundant detectors at various locations in the containment, as necessary, to ensure that the transport delay time of the leakage from its source to the detector (instrument location) will yield an acceptable overall response time... " RG 1.45 suggests that the RCS leakage detection systems should have redundancy, reliability and sensitivity. In Item 2, Enclosure 2, to the licensee's October 8, 2010, response, the licensee stated that the response time for each of the RCS leakage detection systems in Table 1-1 in the Structural Integrity Associates report in the December 22, 2009, submittal is no longer part of the LBB submittal. The licensee provided additional leakage detection information in its response to NRC question E2-2 in the October 8,2010, letter. On page 7 of to the October 8,2010, letter, in response to NRC RAI E2-2, the licensee stated that the daily RCS inventory balance can detect a leak rate of
| |
|
| |
|
| ===0.2 gallons===
| | By letter to the U.S. Nuclear Regulatory Commission (NRC) dated December 22, 2009 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML100200129) as supplemented by letters dated July 23,2010 (ADAMS Accession No. ML102040612), August 20, 2010 (ADAMS Accession No. ML102320535) and October 8, 2010 (ADAMS Accession No. ML102810518), Northern States Power Company, a Minnesota corporation (the licensee), doing business as Xcel Energy, submitted a request for approval to exclude certain postulated pipe ruptures from the licensing basis based upon application of the leak-before-break methodology for Prairie Island Nuclear Generating Plant, Units 1 and 2. |
| per minute (gpm) in 24 hours and that the containment particulate radioactivity monitor (R-11) can detect a leak rate of 0.2 gpm in 53 and 280.7 hours for Units 1 and 2, respectively. RG 1.45 recommends a detection capability of 1 gpm in one hour. The response time for the R-11 monitor exceeds the 1 hour criterion significantly, which brings into question its usefulness in early detection of a pipe crack. The only credible detection method is the daily RCS inventory balance. If that is the case, there appears to be no diverse detectors that can achieve the capability of 0.2 gpm in 24 hours other than the RCS inventory balance. Justify how the RCS leakage detection systems at PINGP have satisfied the redundancy, reliability and sensitivity recommended in RG 1.45. Provide the number of R-11 monitors in the containment.
| | The NRC staff is reviewing your submittal and supplements and has determined that additional information is required to complete the review. The specific information requested is addressed in the enclosure to this letter. During a discussion with Mr. Sam Chesnutt of your staff on November 19, 2010, it was agreed that you would provide a response to this request by December 22, 2010. |
| Enclosure
| | The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for staff review and contribute toward the NRC's goal of efficient and effective use of staff resources. |
| -2On page 10 of the October 8, 2010 response, the licensee stated that the RCS leakage detection system is currently under the status of Operable, But Nonconforming (OBN). The licensee further stated that it is resolving this OBN condition in accordance with the plant corrective action program. The NRC staff has reservations regarding approving an LBB application for a plant with an OBN condition on its RCS leakage detection systems. Discuss when the OBN will be resolved for the leakage detection systems. After the OBN condition is removed, discuss whether the RCS leakage detection capability will satisfy RG 1.45, Revision 1 and in terms of the LBB analysis assumptions. If the leak rate is as low as 0.2 gpm, the leakage would likely be manifested as either steam or small drops on the floor or on the outside surface of other pipes. Within 24 hours, the leakage probably will have evaporated. The RCS inventory balance method is based on the measured inventory that remains in the RCS and letdown systems (i.e., primarily temperature corrected RCS volume based on pressurizer level and volume control tank level changes). This introduces limitations because the calculation is not accurate if temperatures are rapidly changing or if there is significant boration or dilution to control power. Therefore, the NRC staff believes that the RCS inventory balance would not be accurate for a few days during and after startup and for several hours after power changes. The containment radiation monitors (R-11) also may not be effective for the first few days during and after startup because the source term is low. The containment sump would provide leakage detection during this period, but it probably is not sensitive enough to detect a 0.2 gpm leak in part because of leakage evaporation. In light of the above discussion, justify your conclusion that the RCS leakage detection systems have a detection capability of 0.2 gpm in 24 hours. Explain how a substantial margin to the postulated leakage flaw would be maintained considering uncertainties in the release of water and radioactivity from the postulated crack, the potential for the crack to be plugged by particulate debris over time, the response time and accuracy of the leakage detection method, the method of operator identification that the leakage threshold has been exceeded, and the rate of crack growth during the period required for detection. Concerning the licensee's October 8,2010, response to E1-2 Page 7 (Page 1 of 12 of Enclosure 1 with question repeated):
| |
| The licensee stated that when LBB was applied to the RCS loop piping in an LBB evaluation in 1986, a criterion of 1 gallon per minute (gprn) in one hour for RCS leakage was used for the leak detection system capability. | |
| However, for the current submittal, the licensee used a leakage detection limit of 0.2 gpm. The use of O. 2 gpm in the proposed LBB evaluation is an improvement in the leakage detection capability from the original licensing basis of 1 gpm. However, discuss whether the design basis for the RCS leak detection system needs to be changed in the Updated Final Safety Analysis Report and plant technical specifications via a license amendment process. If not, provide justification. The requirements regarding Technical Specification (TS) content are provided in 10 CFR 50.36(c)(2), but the licensee does not address these requirements in its response. The
| |
| -3 licensee cites Generic Letter (GL) 84-04 as not specifying T8 content. However, the GL states that having leak detection capability consistent with RG 1.45 guidelines maintains a large margin against unstable crack extension, and RG 1.45 calls for T8 addressing the availability of leak detection instruments and limits on unidentified leakage. The licensee has identified a leak detection capability more sensitive than that provided in RG 1.45 and considered in development of the current Prairie Island T8, so the licensee's reference to GL 84-04 and the bases of the current Prairie Island T8 does not adequately justify the lack of a proposed revision to the T8s. Therefore, the NRC staff requests the licensee clarify its response to address applicable regulations and guidance.
| |
| M. Schimmel -2 If circumstances result in the need to revise the requested response date, please contact me at (301) 415-4037.
| |
| Sincerely, IRAJ Thomas J. Wengert, Senior Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-282 and Request for Additional cc w/encl:
| |
| Distribution via
| |
|
| |
|
| PUBLIC LPL3-1 R/F RidsNrrDorlLpl3-1 RidsNRRPMPrairielsland Resource RidsNrrLABTully Resource RidsNrrDciCpnb RidsAcrsAcnw_MailCTR Resource RidsOgcRp Resource J. Tsao, RidsRgn3MailCenter Resource RidsNrrDssSbpb Resource S. Jones, ADAMS Accession Number' ML OFFICE LPL3-1/PM LPL3-1/LA NRR/DCI/CPNB/BC NRR/DSS/SBPB/BC LPL3-1/BC NAME TWengert BTuily TLupold GCasto RPascarelli DATE 11/29/10 11/29/10 12/08/10 12/13/10 12/14/10 OFFICIAL RECORD}} | | M. Schimmel -2 If circumstances result in the need to revise the requested response date, please contact me at (301) 415-4037. |
| | Sincerely, |
| | ~~~r Thomas J. Wengert, Senior Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-282 and 50-306 |
| | |
| | ==Enclosure:== |
| | |
| | Request for Additional Information cc w/encl: Distribution via ListServ |
| | |
| | REQUEST FOR ADDITIONAL INFORMATION PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 DOCKET NOS. 50-282 AND 50-306 In reviewing the Northern States Power Company, a Minnesota corporation (NSPM, the licensee), doing business as Xcel Energy, submittal dated December 22,2009 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML100200129), as supplemented by letters dated July 23,2010 (ADAMS Accession No. ML102040612), |
| | August 20, 2010 (ADAMS Accession No. ML102320535), and October 8, 2010 (ADAMS Accession No. ML102810518), which requested approval to exclude certain postulated pipe ruptures from the licensing basis based upon application of the leak-before-break (LBB) methodology for Prairie Island Nuclear Generating Plant (PINGP), Units 1 and 2 (Reference 1), |
| | the U.S. Nuclear Regulatory Commission (NRC) staff has determined that additional information is needed to complete its review. |
| | In its October 8,2010, supplement, the licensee responded to the NRC staff request for additional information (RAI) regarding the reactor coolant system (RCS) leakage detection systems at PINGP. The !\IRC staff has the following clarification questions regarding this RAI response: |
| | : 1. Regulatory Guide (RG) 1.45 states that ". .. plants should use multiple, diverse and redundant detectors at various locations in the containment, as necessary, to ensure that the transport delay time of the leakage from its source to the detector (instrument location) will yield an acceptable overall response time ... " RG 1.45 suggests that the RCS leakage detection systems should have redundancy, reliability and sensitivity. |
| | In Item 2, Enclosure 2, to the licensee's October 8, 2010, response, the licensee stated that the response time for each of the RCS leakage detection systems in Table 1-1 in the Structural Integrity Associates report in the December 22, 2009, submittal is no longer part of the LBB submittal. The licensee provided additional leakage detection information in its response to NRC question E2-2 in the October 8,2010, letter. |
| | On page 7 of Enclosure 1 to the October 8,2010, letter, in response to NRC RAI E2-2, the licensee stated that the daily RCS inventory balance can detect a leak rate of 0.2 gallons per minute (gpm) in 24 hours and that the containment particulate radioactivity monitor (R-11) can detect a leak rate of 0.2 gpm in 53 and 280.7 hours for Units 1 and 2, respectively. RG 1.45 recommends a detection capability of 1 gpm in one hour. The response time for the R-11 monitor exceeds the 1 hour criterion significantly, which brings into question its usefulness in early detection of a pipe crack. The only credible detection method is the daily RCS inventory balance. If that is the case, there appears to be no diverse detectors that can achieve the capability of 0.2 gpm in 24 hours other than the RCS inventory balance. |
| | a) Justify how the RCS leakage detection systems at PINGP have satisfied the redundancy, reliability and sensitivity recommended in RG 1.45. |
| | b) Provide the number of R-11 monitors in the containment. |
| | Enclosure |
| | |
| | -2 |
| | : 2. On page 10 of the October 8, 2010 response, the licensee stated that the RCS leakage detection system is currently under the status of Operable, But Nonconforming (OBN). |
| | The licensee further stated that it is resolving this OBN condition in accordance with the plant corrective action program. The NRC staff has reservations regarding approving an LBB application for a plant with an OBN condition on its RCS leakage detection systems. |
| | Discuss when the OBN will be resolved for the leakage detection systems. After the OBN condition is removed, discuss whether the RCS leakage detection capability will satisfy RG 1.45, Revision 1 and in terms of the LBB analysis assumptions. |
| | : 3. If the leak rate is as low as 0.2 gpm, the leakage would likely be manifested as either steam or small drops on the floor or on the outside surface of other pipes. Within 24 hours, the leakage probably will have evaporated. The RCS inventory balance method is based on the measured inventory that remains in the RCS and letdown systems (i.e., primarily temperature corrected RCS volume based on pressurizer level and volume control tank level changes). This introduces limitations because the calculation is not accurate if temperatures are rapidly changing or if there is significant boration or dilution to control power. Therefore, the NRC staff believes that the RCS inventory balance would not be accurate for a few days during and after startup and for several hours after power changes. The containment radiation monitors (R-11) also may not be effective for the first few days during and after startup because the source term is low. The containment sump would provide leakage detection during this period, but it probably is not sensitive enough to detect a 0.2 gpm leak in part because of leakage evaporation. |
| | a) In light of the above discussion, justify your conclusion that the RCS leakage detection systems have a detection capability of 0.2 gpm in 24 hours. |
| | b) Explain how a substantial margin to the postulated leakage flaw would be maintained considering uncertainties in the release of water and radioactivity from the postulated crack, the potential for the crack to be plugged by particulate debris over time, the response time and accuracy of the leakage detection method, the method of operator identification that the leakage threshold has been exceeded, and the rate of crack growth during the period required for detection. |
| | : 4. Concerning the licensee's October 8,2010, response to E1-2 Page 7 (Page 1 of 12 of Enclosure 1 with question repeated): |
| | The licensee stated that when LBB was applied to the RCS loop piping in an LBB evaluation in 1986, a criterion of 1 gallon per minute (gprn) in one hour for RCS leakage was used for the leak detection system capability. However, for the current submittal, the licensee used a leakage detection limit of 0.2 gpm. The use of O. 2 gpm in the proposed LBB evaluation is an improvement in the leakage detection capability from the original licensing basis of 1 gpm. However, discuss whether the design basis for the RCS leak detection system needs to be changed in the Updated Final Safety Analysis Report and plant technical specifications via a license amendment process. If not, provide justification. |
| | The requirements regarding Technical Specification (TS) content are provided in 10 CFR 50.36(c)(2), but the licensee does not address these requirements in its response. The |
| | |
| | -3 licensee cites Generic Letter (GL) 84-04 as not specifying T8 content. However, the GL states that having leak detection capability consistent with RG 1.45 guidelines maintains a large margin against unstable crack extension, and RG 1.45 calls for T8 addressing the availability of leak detection instruments and limits on unidentified leakage. The licensee has identified a leak detection capability more sensitive than that provided in RG 1.45 and considered in development of the current Prairie Island T8, so the licensee's reference to GL 84-04 and the bases of the current Prairie Island T8 does not adequately justify the lack of a proposed revision to the T8s. Therefore, the NRC staff requests the licensee clarify its response to address applicable regulations and guidance. |
| | |
| | M. Schimmel -2 If circumstances result in the need to revise the requested response date, please contact me at (301) 415-4037. |
| | Sincerely, IRAJ Thomas J. Wengert, Senior Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-282 and 50-306 |
| | |
| | ==Enclosure:== |
| | |
| | Request for Additional Information cc w/encl: Distribution via ListServ DISTRIBUTION: |
| | PUBLIC LPL3-1 R/F RidsNrrDorlLpl3-1 Resource RidsNRRPMPrairielsland Resource RidsNrrLABTully Resource RidsNrrDciCpnb Resource RidsAcrsAcnw_MailCTR Resource RidsOgcRp Resource J. Tsao, NRR RidsRgn3MailCenter Resource RidsNrrDssSbpb Resource S. Jones, NRR ADAMS Accession Number' ML103280398 OFFICE LPL3-1/PM LPL3-1/LA NRR/DCI/CPNB/BC NRR/DSS/SBPB/BC LPL3-1/BC NAME TWengert BTuily TLupold GCasto RPascarelli DATE 11/29/10 11/29/10 12/08/10 12/13/10 12/14/10 OFFICIAL RECORD COPY}} |
Letter Sequence RAI |
|---|
|
|
MONTHYEARML1002001312009-12-21021 December 2009
Report No. 0900634.401, Revision 2, Updated Leak-Before-Break Evaluation for Several RCS Piping at Prairie Island Nuclear Generating Plant, Units 1 & 2.
Project stage: Request
ML1005701342010-02-25025 February 2010
Acceptance Review of LAR to Apply Leak-Before-Break Methodology (TAC Nos. ME2976 and ME2977
Project stage: Acceptance Review
ML1011802112010-05-0606 May 2010
Request for Withholding Information from Public Disclosure for Prairie Island Nuclear Generating Plant, Units 1 and 2
Project stage: Withholding Request Acceptance
ML1011708332010-05-0606 May 2010
Request for Withholding Information from Public Disclosure for Prairie Island Nuclear Generating Plant, Units 1 and 2
Project stage: Withholding Request Acceptance
ML1011708142010-05-0606 May 2010
Request for Withholding Information from Public Disclosure for Prairie Island Nuclear Generation Plant, Units 1 and 2
Project stage: Withholding Request Acceptance
ML1015506682010-06-10010 June 2010
Request for Additional Information Related to License Amendment Request to Exclude the Dynamic Effects Associated with Certain Postulated Pipe Ruptures from the Licensing Basis Based Upon Application of Leak-before-Break
Project stage: RAI
L-PI-10-077, Supplement to License Amendment Request to Exclude the Dynamic Effects Associated with Certain Postulated Pipe Ruptures from the Licensing Basis Based Upon Application of Leak-Before-Break Methodology Additional ...2010-07-23023 July 2010
Supplement to License Amendment Request to Exclude the Dynamic Effects Associated with Certain Postulated Pipe Ruptures from the Licensing Basis Based Upon Application of Leak-Before-Break Methodology Additional ...
Project stage: Supplement
L-PI-10-085, Clarification of Responses to Requests for Additional Information Regarding a License Amendment Request for Certain Applications of Leak-Before-Break Methodology2010-08-20020 August 2010
Clarification of Responses to Requests for Additional Information Regarding a License Amendment Request for Certain Applications of Leak-Before-Break Methodology
Project stage: Response to RAI
L-PI-10-094, Supplement to License Amendment Request to Exclude the Dynamic Effects Associated with Certain Postulated Pipe Ruptures from the Licensing Basis Based Upon Application of Leak-Before-Break Methodology - Response to RAI2010-10-0808 October 2010
Supplement to License Amendment Request to Exclude the Dynamic Effects Associated with Certain Postulated Pipe Ruptures from the Licensing Basis Based Upon Application of Leak-Before-Break Methodology - Response to RAI
Project stage: Supplement
ML1032803982010-12-14014 December 2010
RAI, Related to Request to Exclude the Dynamic Effects Associated with Certain Postulated Pipe Ruptures from the Licensing Basis Based Upon Application of LBB Methodology
Project stage: RAI
L-PI-11-006, Supplement to License Amendment Request to Exclude the Dynamic Effects Associated with Certain Postulated Pipe Ruptures from the Licensing Basis Based Upon Application of Leak-Before-Break Methodology - Response to RAI2011-01-14014 January 2011
Supplement to License Amendment Request to Exclude the Dynamic Effects Associated with Certain Postulated Pipe Ruptures from the Licensing Basis Based Upon Application of Leak-Before-Break Methodology - Response to RAI
Project stage: Supplement
L-PI-11-019, Supplement to License Amendment Request to Exclude Dynamic Effects Associated with Certain Postulated Pipe Ruptures from Licensing Basis Based Upon Application of Leak-Before-Break Methodology - Response to Requests for Clarification2011-02-23023 February 2011
Supplement to License Amendment Request to Exclude Dynamic Effects Associated with Certain Postulated Pipe Ruptures from Licensing Basis Based Upon Application of Leak-Before-Break Methodology - Response to Requests for Clarification
Project stage: Supplement
L-PI-11-038, Supplement to License Amendment Request to Exclude the Dynamic Effects Associated with Certain Postulated Pipe Ruptures from the Licensing Basis Based Upon Application of Leak-Before-Break Methodology2011-04-0606 April 2011
Supplement to License Amendment Request to Exclude the Dynamic Effects Associated with Certain Postulated Pipe Ruptures from the Licensing Basis Based Upon Application of Leak-Before-Break Methodology
Project stage: Supplement
ML1120106962011-07-22022 July 2011
RAI, Related to Request to Exclude the Dynamic Effects Associated with Certain Postulated Pipe Ruptures from the Licensing Basis Based Upon Application of Leak-Before-Break Methodology
Project stage: RAI
L-PI-11-070, Supplement to License Amendment Request to Exclude Dynamic Effects Associated with Certain Postulated Pipe Ruptures from the Licensing Basis Based Upon Application of Leak-Before-Break Methodology - Response to RAI2011-08-0909 August 2011
Supplement to License Amendment Request to Exclude Dynamic Effects Associated with Certain Postulated Pipe Ruptures from the Licensing Basis Based Upon Application of Leak-Before-Break Methodology - Response to RAI
Project stage: Supplement
ML1122008562011-10-27027 October 2011
Operating Plant, Units 1 and 2 - Issuance of Amendments Request to Exclude the Dynamic Effects Associated with Certain Postulated Pipe Ruptures from the Licensing Basis Based Upon Application of Leak-Before-Break Methodology
Project stage: Approval
2010-07-23
[Table View] |
|
|---|
Category:Request for Additional Information (RAI)
MONTHYEARML24197A2012024-07-15015 July 2024
Notification of NRC Baseline Inspection and Request for Information; Inspection Report 05000282/2024004
ML24149A3712024-05-29029 May 2024
(Ping) - Information Request for the Cyber-Security Baseline Inspection, Notification to Perform Inspection
ML24141A0452024-05-20020 May 2024
Information Request to Support the NRC Annual Baseline Emergency Action Level and Emergency Plan Changes Inspection
ML24116A2532024-04-25025 April 2024
Final Request for Additional Information for LAR to Revise SR 3.8.1.2 Note 3 (EPID: L- 2023-LLA-0135)
ML24045A0862024-02-12012 February 2024
Final RAI for Alternative RR-09
ML23335A1152023-12-0101 December 2023
NRR E-mail Capture - Prairie Island Units 1 and 2 - Request for Additional Information LAR to Revise TS 3.7.8 Required Actions
ML23248A3462023-09-0505 September 2023
NRR E-mail Capture - Request for Additional Information for Monticello Nuclear Generating Plant and Prairie Island Nuclear Generating Plant - Decommissioning Funding Status Reports
ML23214A2032023-08-0202 August 2023
Request for Information for an NRC Quadrennial Comprehensive Engineering Team Inspection: Inspection Report 05000282/2024010; 05000306/2024010
ML23199A0922023-07-18018 July 2023
Notification of NRC Baseline Inspection and Request for Information; Inspection Report 05000306/2023004
ML23096A3082023-04-0707 April 2023
Notification of Inspection an NRC Biennial Licensed Operator Requalification Program Inspection and Request for Information
ML23055B0562023-02-27027 February 2023
Request for Information for NRC Commercial Grade Dedication Inspection Inspection Report 05000282/2023010 and 05000306/2023010
ML23053A1432023-02-22022 February 2023
Information Request to Support Upcoming Problem Identification and Resolution (Pi&R) Inspection at Prairie Island Nuclear Generating Plant
ML22166A4112022-06-15015 June 2022
NRR E-mail Capture - Request for Additional Information Prairie Island Nuclear Generating Plant, Unit 2, Alternative RR-08, PIV Leakage
ML22160A6022022-06-0909 June 2022
NRR E-mail Capture - Draft Request for Additional Information Prairie Island Nuclear Generating Plant, Units 1 and 2, 24-Month Operating Cycle Amendment
IR 05000282/20224022022-05-25025 May 2022
Information Request for the Cyber-Security Baseline Inspection, Notification to Perform Inspection 05000282/2022402 05000306/2022402
ML22131A2652022-05-11011 May 2022
NRR E-mail Capture - Request for Additional Information Xcel Energy Amendment Request to Create a Common Eplan and EOF for Monticello and Prairie Island
ML22130A5792022-05-11011 May 2022
Information Request to Support the NRC Annual Baseline Emergency Action Level and Emergency Plan Changes Inspection
ML21321A0452021-11-10010 November 2021
Request for Additional Information: Prairie Island 24-Month Cycle Amendment Request
ML21305A0102021-10-29029 October 2021
NRR E-mail Capture - Request for Additional Information Prairie Island Cooling Water Amendment
ML21252A0122021-08-30030 August 2021
NRR E-mail Capture - Request for Additional Information Amendment Request to Adopt TSTF-471 and 517-T for Prairie Island
ML21147A5232021-06-0303 June 2021
Prarie Island Nuclear Generating Plant, Units 1 and 2 - Information Request to Support the NRC Annual Baseline Emergency Action Level and Emergency Plan Changes Inspection
ML21131A0752021-05-10010 May 2021
Notification of NRC Baseline Inspection and Request for Information; Inspection Report 05000282/2021004; 05000306/2021004
ML21099A0972021-04-0909 April 2021
Information Request to Support Upcoming Temporary Instruction 2515/194 Inspection; Inspection Report 05000282/2021012 and 05000306/2021012
ML21062A0532021-03-0202 March 2021
Information Request to Support Upcomng Problem Identification and Resolution (Pi&R) Inspection at the Prairie Island Nuclear Generating Plant
ML21033A6112021-02-0101 February 2021
Request for Information for an NRC Triennial Baseline Design Bases Assurance Inspection (Team); Inspection Report 05000282/2021010 and 05000306/2021010
ML20343A1292020-12-0808 December 2020
NRR E-mail Capture - Request for Additional Information
ML20192A1442020-07-0707 July 2020
NRR E-mail Capture - Request for Additional Information Prairie Island License Amendment Request to Adopt TSTF-505
ML20189A1782020-07-0606 July 2020
Notification of NRC Baseline Inspection and Request for Information; Inspection Report 05000282/2020004; 05000306/2020004
ML20133K0692020-05-14014 May 2020
Information Request to Support the NRC Annual Baseline Emergency Action Level and Emergency Plan Changes Inspection
ML20077K6242020-04-13013 April 2020
License Amendment Request - Request for Additional Information
ML20052F4102020-02-21021 February 2020
Notification of Nrc Design Bases Assurance Inspection (Programs) (05000282/202010; 05000306/202010) and Initial Request for Information
ML20035F1552020-02-0404 February 2020
NRR E-mail Capture - Request for Additional Information Monticello and Prairie Island Alternative Requests to Adopt Code Cases N-786-3 and N-789-3 (Epids: L-2019-LLR-0078 and L-2019-LLR-0079)
ML19233A0032019-08-14014 August 2019
NRR E-mail Capture - Request for Additional Information Prairie Island Relief Requests 1-RR-10 and 2-RR-10
ML19057A1652019-02-26026 February 2019
NRR E-mail Capture - Request for Additional Information Prairie Island 50.69 Amendment Request
ML18313A0832018-11-0707 November 2018
NRR E-mail Capture - Request for Additional Information Prairie Island NFPA-805 License Condition Modification Amendment Request
ML18264A1912018-09-19019 September 2018
NRC Information Request (9/19/2018); Part B Items (Onsite) IP 71111.08 - E-Mailed 09/19/18 (DRS-M.Holmberg)
ML18235A2982018-08-23023 August 2018
NRR E-mail Capture - Request for Additional Information Prairie Island TSTF-425 License Amendment Request
ML18169A4202018-06-25025 June 2018
Supplemental Information Needed for Acceptance of Requested Licensing Action Amendment to Modify Renewed Facility Operating License Paragraph 2.C(4)(c)
ML18025C0152018-01-24024 January 2018
Request for Information for an NRC Triennial Baseline Design Bases Assurance Inspection (Team): Inspection Report 05000282/2018011; 05000306/2018011 (DRS-A.Dunlop)
ML17277B3332017-10-0404 October 2017
NRR E-mail Capture - Request for Additional Information Prairie Island Special Heavy Lifting Devices LAR
ML17249A9232017-09-0606 September 2017
Notification of NRC Baseline Inspection and Request for Information; Inspection Report 05000282/2017004; 05000306/2017004 (Exf)
ML17235A9982017-08-23023 August 2017
NRR E-mail Capture - Request for Additional Information Prairie Island EAL Scheme Change
ML17221A3892017-08-0909 August 2017
NRR E-mail Capture - Request for Additional Information for Prairie Island Nuclear Generating Plant License Amendment Request Dated February 23, 2017 Emergency Response Organization
ML17219A0762017-08-0707 August 2017
NRR E-mail Capture - Request for Additional Information for Prairie Island Nuclear Generating Plant License Amendment Request Dated February 23, 2017 Emergency Response Organization
ML17038A5132017-02-0707 February 2017
NRR E-mail Capture - Prairie Island NFPA 805 LAR, PRA RAI 21.01
ML17018A4272017-01-18018 January 2017
NRR E-mail Capture - Request for Additional Information: Prairie Island License Amendment Request to Revise Technical Specification 3.8.7 to Remove Non-Conservative Required Action
ML16326A3532016-11-18018 November 2016
NRR E-mail Capture - Draft Request for Information Related to Prairie Island NFPA-805 License Amendment
ML16265A1652016-09-20020 September 2016
Notification of an NRC Triennial Heat Sink Performance Inspection and Request for Information; Inspection Report 05000282/2016004; 05000306/2016004 (Gfo)
ML16189A2052016-07-0707 July 2016
Notification of NRC Inspection and Request for Information
ML16113A1612016-04-21021 April 2016
Information Request to Support Upcoming Problem Identification and Resolution (Pi&R) Inspection at Prairie Island Nuclear Generating Plant, Units 1 and 2
2024-07-15
[Table view]
Category:Letter
MONTHYEARML24298A0552024-10-30030 October 2024
Response to Alternative RR-10, Auxiliary Feedwater Valve Testing
IR 05000282/20244032024-10-25025 October 2024
– Security Baseline Inspection Report 05000282/2024403 and 05000306/2024403
05000282/LER-2024-001-01, Auxiliary Building Special Ventilation System Inoperable During Movement of Irradiated Fuel Assemblies2024-10-22022 October 2024
Auxiliary Building Special Ventilation System Inoperable During Movement of Irradiated Fuel Assemblies
L-PI-24-044, Application to Revise Technical Specifications to Adopt TSTF-591, Revise Risk Informed Completion Time (RICT) Program2024-10-21021 October 2024
Application to Revise Technical Specifications to Adopt TSTF-591, Revise Risk Informed Completion Time (RICT) Program
ML24277A1012024-10-0303 October 2024
Closure of Interim Report of a Potential Deviation or Failure to Comply Associated with Bentley Systems Incorporated Autopipe Software
ML24221A3622024-09-27027 September 2024
Issuance of Amendment Nos. 245 and 233 Revise Technical Specification 3.8.1, AC Sources-Operating, Surveillance Requirement 3.8.1.2, Note 3
ML24241A1682024-09-23023 September 2024
Transmittal Letter Amendment No. 13 to Materials License No. Special Nuclear Material-2506 for the Prairie Island Independent Spent Fuel Storage Installation
05000282/LER-2024-001, Auxiliary Building Special Ventilation System Inoperable During Movement of Irradiated Fuel Assemblies2024-09-16016 September 2024
Auxiliary Building Special Ventilation System Inoperable During Movement of Irradiated Fuel Assemblies
IR 05000282/20243012024-09-13013 September 2024
NRC Initial License Examination Report 05000282/2024301 and 05000306/2024301
IR 05000282/20240052024-08-28028 August 2024
Updated Inspection Plan and Assessment Follow-Up Letter for Prairie Island Nuclear Generating Plant, Units 1 and 2 (Report 05000282/2024005 and 05000306/2024005)
L-PI-24-040, Post-Submittal Package Letter2024-08-23023 August 2024
Post-Submittal Package Letter
IR 05000282/20245012024-08-0505 August 2024
Emergency Preparedness Inspection Report 05000282/2024501 and 05000306/2024501
ML24213A1592024-07-31031 July 2024
Operator Licensing Examination Approval - Prairie Island Nuclear Generating Plant
IR 05000282/20240022024-07-30030 July 2024
Integrated Inspection Report 05000282/2024002 and 05000306/2024002
ML24208A1502024-07-26026 July 2024
Independent Spent Fuel Storage Installation - Submittal of Quality Assurance Topical Report (NSPM-1)
ML24197A2012024-07-15015 July 2024
Notification of NRC Baseline Inspection and Request for Information; Inspection Report 05000282/2024004
IR 05000282/20240102024-06-28028 June 2024
Comprehensive Engineering Team Inspection Report 05000282/2024010 and 05000306/2024010
L-PI-24-036, – Preparation and Scheduling of Operator Licensing Examinations2024-06-28028 June 2024
– Preparation and Scheduling of Operator Licensing Examinations
ML24158A5912024-06-0606 June 2024
CFR 50.46 LOCA Annual Report
L-PI-24-031, Independent Spent Fuel Storage Installation, Supplement to License Amendment Request to Revise Independent Spent Fuel Storage Installation (ISFSI) License Conditions 23(a), 24(A)(2), and 24(B)(2)2024-06-0505 June 2024
Independent Spent Fuel Storage Installation, Supplement to License Amendment Request to Revise Independent Spent Fuel Storage Installation (ISFSI) License Conditions 23(a), 24(A)(2), and 24(B)(2)
L-PI-24-014, License Amendment Request to Revise the Technical Specification Definition of Reactor Trip System (RTS) Response Time and Apply Response Time Testing to RTS Trip Functions with Time Delay Assumption2024-06-0303 June 2024
License Amendment Request to Revise the Technical Specification Definition of Reactor Trip System (RTS) Response Time and Apply Response Time Testing to RTS Trip Functions with Time Delay Assumption
05000306/LER-2024-001-01, Reactor Trip and Auto-Start Actuation of Auxiliary Feedwater Due to Loss of Suction to the 22 Main Feedwater Pump2024-05-31031 May 2024
Reactor Trip and Auto-Start Actuation of Auxiliary Feedwater Due to Loss of Suction to the 22 Main Feedwater Pump
ML24155A1922024-05-31031 May 2024
Refueling Outage Unit 2 R33 Owners Activity Report for Class 1, 2, 3 and Mc Inservice Inspections
ML24262A1992024-05-29029 May 2024
L-PI-24-018 PINGP 75 Day Letter
ML24149A3712024-05-29029 May 2024
(Ping) - Information Request for the Cyber-Security Baseline Inspection, Notification to Perform Inspection
L-PI-24-030, Response to Request for Additional Information Regarding License Amendment Request to Revise Technical Specification 3.8.12024-05-22022 May 2024
Response to Request for Additional Information Regarding License Amendment Request to Revise Technical Specification 3.8.1
ML24141A1292024-05-22022 May 2024
Northern States Power Company - Use of Encryption Software for Electronic Transmission of Safeguards Information
ML24141A0452024-05-20020 May 2024
Information Request to Support the NRC Annual Baseline Emergency Action Level and Emergency Plan Changes Inspection
ML24128A2572024-05-16016 May 2024
ISFSI A13 Acceptance Letter
IR 05000282/20240012024-05-15015 May 2024
Integrated Inspection Report 05000282/2024001 and 05000306/2024001
ML24130A2362024-05-0909 May 2024
Independent Spent Fuel Storage Installation - 2023 Annual Radiological Environmental Monitoring Program Report
ML24130A2392024-05-0909 May 2024
2023 Annual Radioactive Effluent Report
ML24071A1162024-05-0101 May 2024
Issuance of Amendment Nos. 244 and 232 Revise TS 3.7.8, Cooling Water (Cl) System
ML24128A0882024-04-30030 April 2024
Submittal of Updated Safety Analysis Report (Usar), Revision 38
05000306/LER-2024-001, Reactor Trip and Auto-Start Actuation of Auxiliary Feedwater Due to Loss of Suction to the 22 Main Feedwater Pump2024-04-29029 April 2024
Reactor Trip and Auto-Start Actuation of Auxiliary Feedwater Due to Loss of Suction to the 22 Main Feedwater Pump
ML24089A2382024-04-29029 April 2024
Summary of Nuclear Property Insurance
IR 05000282/20244012024-04-25025 April 2024
– Security Baseline Inspection Report 05000282/2024401 and 05000306/2024401
ML24100A8042024-04-24024 April 2024
– Alternative Request RR-09 for Safety Injection and Volume Control System Category C Check Valve Inservice Testing
ML24114A0882024-04-23023 April 2024
Annual Report of Individual Monitoring for the Prairie Island Nuclear Generating Plant (PINGP)
ML24113A1182024-04-12012 April 2024
NRC Letter Re NRC Office of Investigations Report No. 3-2023-004
ML24100A1212024-04-0909 April 2024
Submittal of Revised Pressure and Temperature Limits Report
ML24093A2832024-04-0202 April 2024
Nuclear Material Transaction Report
L-PI-24-012, Independent Spent Fuel Storage Installation - License Amendment Request: Revise Independent Spent Fuel Storage Installation (ISFSI) License Conditions 23(a), 24(A)(2), and 24(B)(2)2024-04-0202 April 2024
Independent Spent Fuel Storage Installation - License Amendment Request: Revise Independent Spent Fuel Storage Installation (ISFSI) License Conditions 23(a), 24(A)(2), and 24(B)(2)
ML24089A2402024-03-29029 March 2024
Guarantee of Payment of Deferred Premiums
ML24060A1232024-03-27027 March 2024
To Request 1-RR-5-10 and 2-RR-5-10 Regarding Reactor Pressure Vessel Welds and Nozzle Welds
05000282/LER-2023-001-01, Reactor Trip, Auxiliary Feedwater and Emergency Service Water System Actuation Due to Electrical Transient in DC Control Power Cables2024-03-21021 March 2024
Reactor Trip, Auxiliary Feedwater and Emergency Service Water System Actuation Due to Electrical Transient in DC Control Power Cables
ML24262A1512024-03-15015 March 2024
L-PI-24-011 150 Day Letter 2024 PINGP ILT NRC Exam
ML24010A0582024-03-0505 March 2024
Amendment No. 12 to Materials License No. Special Nuclear Material-2506 for the Prairie Island Independent Spent Fuel Storage Installation
L-PI-24-004, Independent Spent Fuel Storage Installation - Annual Effluent Report, January Through December 20232024-02-29029 February 2024
Independent Spent Fuel Storage Installation - Annual Effluent Report, January Through December 2023
IR 05000282/20230062024-02-28028 February 2024
Annual Assessment Letter for Prairie Island Nuclear Generating Plant, Units 1 and 2 (Report 05000282/2023006 and 05000306/2023006)
2024-09-27
[Table view] |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 December 14, 2010 Mr. Mark A. Schimmel Site Vice President Prairie Island Nuclear Generating Plant Northern States Power Company - Minnesota 1717 Wakonade Drive East Welch, MN 55089-9642 SUB~IECT: PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 REQUEST FOR ADDITIONAL INFORMATION RELATED TO REQUEST TO EXCLUDE THE DYNAMIC EFFECTS ASSOCIATED WITH CERTAIN POSTULATED PIPE RUPTURES FROM THE LICENSING BASIS BASED UPON APPLICATION OF LEAK-BEFORE-BREAK METHODOLOGY (TAC NOS.
ME2976 AND ME2977)
Dear Mr. Schimmel:
By letter to the U.S. Nuclear Regulatory Commission (NRC) dated December 22, 2009 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML100200129) as supplemented by letters dated July 23,2010 (ADAMS Accession No. ML102040612), August 20, 2010 (ADAMS Accession No. ML102320535) and October 8, 2010 (ADAMS Accession No. ML102810518), Northern States Power Company, a Minnesota corporation (the licensee), doing business as Xcel Energy, submitted a request for approval to exclude certain postulated pipe ruptures from the licensing basis based upon application of the leak-before-break methodology for Prairie Island Nuclear Generating Plant, Units 1 and 2.
The NRC staff is reviewing your submittal and supplements and has determined that additional information is required to complete the review. The specific information requested is addressed in the enclosure to this letter. During a discussion with Mr. Sam Chesnutt of your staff on November 19, 2010, it was agreed that you would provide a response to this request by December 22, 2010.
The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for staff review and contribute toward the NRC's goal of efficient and effective use of staff resources.
M. Schimmel -2 If circumstances result in the need to revise the requested response date, please contact me at (301) 415-4037.
Sincerely,
~~~r Thomas J. Wengert, Senior Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-282 and 50-306
Enclosure:
Request for Additional Information cc w/encl: Distribution via ListServ
REQUEST FOR ADDITIONAL INFORMATION PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 DOCKET NOS. 50-282 AND 50-306 In reviewing the Northern States Power Company, a Minnesota corporation (NSPM, the licensee), doing business as Xcel Energy, submittal dated December 22,2009 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML100200129), as supplemented by letters dated July 23,2010 (ADAMS Accession No. ML102040612),
August 20, 2010 (ADAMS Accession No. ML102320535), and October 8, 2010 (ADAMS Accession No. ML102810518), which requested approval to exclude certain postulated pipe ruptures from the licensing basis based upon application of the leak-before-break (LBB) methodology for Prairie Island Nuclear Generating Plant (PINGP), Units 1 and 2 (Reference 1),
the U.S. Nuclear Regulatory Commission (NRC) staff has determined that additional information is needed to complete its review.
In its October 8,2010, supplement, the licensee responded to the NRC staff request for additional information (RAI) regarding the reactor coolant system (RCS) leakage detection systems at PINGP. The !\IRC staff has the following clarification questions regarding this RAI response:
- 1. Regulatory Guide (RG) 1.45 states that ". .. plants should use multiple, diverse and redundant detectors at various locations in the containment, as necessary, to ensure that the transport delay time of the leakage from its source to the detector (instrument location) will yield an acceptable overall response time ... " RG 1.45 suggests that the RCS leakage detection systems should have redundancy, reliability and sensitivity.
In Item 2, Enclosure 2, to the licensee's October 8, 2010, response, the licensee stated that the response time for each of the RCS leakage detection systems in Table 1-1 in the Structural Integrity Associates report in the December 22, 2009, submittal is no longer part of the LBB submittal. The licensee provided additional leakage detection information in its response to NRC question E2-2 in the October 8,2010, letter.
On page 7 of Enclosure 1 to the October 8,2010, letter, in response to NRC RAI E2-2, the licensee stated that the daily RCS inventory balance can detect a leak rate of 0.2 gallons per minute (gpm) in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and that the containment particulate radioactivity monitor (R-11) can detect a leak rate of 0.2 gpm in 53 and 280.7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> for Units 1 and 2, respectively. RG 1.45 recommends a detection capability of 1 gpm in one hour. The response time for the R-11 monitor exceeds the 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> criterion significantly, which brings into question its usefulness in early detection of a pipe crack. The only credible detection method is the daily RCS inventory balance. If that is the case, there appears to be no diverse detectors that can achieve the capability of 0.2 gpm in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> other than the RCS inventory balance.
a) Justify how the RCS leakage detection systems at PINGP have satisfied the redundancy, reliability and sensitivity recommended in RG 1.45.
b) Provide the number of R-11 monitors in the containment.
Enclosure
-2
- 2. On page 10 of the October 8, 2010 response, the licensee stated that the RCS leakage detection system is currently under the status of Operable, But Nonconforming (OBN).
The licensee further stated that it is resolving this OBN condition in accordance with the plant corrective action program. The NRC staff has reservations regarding approving an LBB application for a plant with an OBN condition on its RCS leakage detection systems.
Discuss when the OBN will be resolved for the leakage detection systems. After the OBN condition is removed, discuss whether the RCS leakage detection capability will satisfy RG 1.45, Revision 1 and in terms of the LBB analysis assumptions.
- 3. If the leak rate is as low as 0.2 gpm, the leakage would likely be manifested as either steam or small drops on the floor or on the outside surface of other pipes. Within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the leakage probably will have evaporated. The RCS inventory balance method is based on the measured inventory that remains in the RCS and letdown systems (i.e., primarily temperature corrected RCS volume based on pressurizer level and volume control tank level changes). This introduces limitations because the calculation is not accurate if temperatures are rapidly changing or if there is significant boration or dilution to control power. Therefore, the NRC staff believes that the RCS inventory balance would not be accurate for a few days during and after startup and for several hours after power changes. The containment radiation monitors (R-11) also may not be effective for the first few days during and after startup because the source term is low. The containment sump would provide leakage detection during this period, but it probably is not sensitive enough to detect a 0.2 gpm leak in part because of leakage evaporation.
a) In light of the above discussion, justify your conclusion that the RCS leakage detection systems have a detection capability of 0.2 gpm in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
b) Explain how a substantial margin to the postulated leakage flaw would be maintained considering uncertainties in the release of water and radioactivity from the postulated crack, the potential for the crack to be plugged by particulate debris over time, the response time and accuracy of the leakage detection method, the method of operator identification that the leakage threshold has been exceeded, and the rate of crack growth during the period required for detection.
- 4. Concerning the licensee's October 8,2010, response to E1-2 Page 7 (Page 1 of 12 of Enclosure 1 with question repeated):
The licensee stated that when LBB was applied to the RCS loop piping in an LBB evaluation in 1986, a criterion of 1 gallon per minute (gprn) in one hour for RCS leakage was used for the leak detection system capability. However, for the current submittal, the licensee used a leakage detection limit of 0.2 gpm. The use of O. 2 gpm in the proposed LBB evaluation is an improvement in the leakage detection capability from the original licensing basis of 1 gpm. However, discuss whether the design basis for the RCS leak detection system needs to be changed in the Updated Final Safety Analysis Report and plant technical specifications via a license amendment process. If not, provide justification.
The requirements regarding Technical Specification (TS) content are provided in 10 CFR 50.36(c)(2), but the licensee does not address these requirements in its response. The
-3 licensee cites Generic Letter (GL) 84-04 as not specifying T8 content. However, the GL states that having leak detection capability consistent with RG 1.45 guidelines maintains a large margin against unstable crack extension, and RG 1.45 calls for T8 addressing the availability of leak detection instruments and limits on unidentified leakage. The licensee has identified a leak detection capability more sensitive than that provided in RG 1.45 and considered in development of the current Prairie Island T8, so the licensee's reference to GL 84-04 and the bases of the current Prairie Island T8 does not adequately justify the lack of a proposed revision to the T8s. Therefore, the NRC staff requests the licensee clarify its response to address applicable regulations and guidance.
M. Schimmel -2 If circumstances result in the need to revise the requested response date, please contact me at (301) 415-4037.
Sincerely, IRAJ Thomas J. Wengert, Senior Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-282 and 50-306
Enclosure:
Request for Additional Information cc w/encl: Distribution via ListServ DISTRIBUTION:
PUBLIC LPL3-1 R/F RidsNrrDorlLpl3-1 Resource RidsNRRPMPrairielsland Resource RidsNrrLABTully Resource RidsNrrDciCpnb Resource RidsAcrsAcnw_MailCTR Resource RidsOgcRp Resource J. Tsao, NRR RidsRgn3MailCenter Resource RidsNrrDssSbpb Resource S. Jones, NRR ADAMS Accession Number' ML103280398 OFFICE LPL3-1/PM LPL3-1/LA NRR/DCI/CPNB/BC NRR/DSS/SBPB/BC LPL3-1/BC NAME TWengert BTuily TLupold GCasto RPascarelli DATE 11/29/10 11/29/10 12/08/10 12/13/10 12/14/10 OFFICIAL RECORD COPY
