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Category:Letter
MONTHYEARML24302A1952024-11-0101 November 2024 Ltr to M. Olivas Tucker Ytt Re DCPP Dseis ML24302A1972024-11-0101 November 2024 Letter to V. Sage Walker Northern Chumash Tribal Council Re DCPP Dseis ML24302A1962024-11-0101 November 2024 Ltr to SLO County Chumash Indians Re DCPP Dseis ML24302A2612024-11-0101 November 2024 Letter to Achp Re DCPP Dseis ML24302A1942024-11-0101 November 2024 Ltr to K. Kahn Santa Ynez Band of Chumash Indians Re DCPP Dseis ML24302A1912024-11-0101 November 2024 Ltr to C. Mcdarment Tule River Tribe Re DCPP Dseis ML24302A2622024-11-0101 November 2024 Letter to CA SHPO Regarding DCPP Dseis ML24302A1932024-11-0101 November 2024 Letter to G. Pierce Salinan Tribe of Monterey, SLO Re DCPP Dseis ML24302A1922024-11-0101 November 2024 Ltr to G. Frausto Coastal Band of Chumash Indians Re DCPP Dseis IR 05000275/20240032024-10-30030 October 2024 Integrated Inspection Report 05000275/2024003 and 05000323/2024003 and Independent Spent Fuel Storage Installation Report 07200026/2024001 ML24275A0622024-10-30030 October 2024 NRC to NMFS Request Initiate Formal Endangered Species Act Consultation and Abbreviated Essential Fish Habitat for Proposed License Renewal of DCP Plant Units 1, 2 ML24269A0122024-10-29029 October 2024 OEDO-24-00083 2.206 Petition Diablo Canyon Seismic CDF - Response to Petitioner Letter ML24284A3122024-10-28028 October 2024 Ltr to P Ting, Diablo Canyon Nuclear Power Plant Units 1 and 2 Notice of Avail of Draft Supplement 62 to the GEIS for Lic Renew of Nuclear Plants ML24284A3112024-10-28028 October 2024 Ltr to a Peck, Diablo Canyon Nuclear Power Plant Units 1 and 2 Notice of Avail of Draft Supplement 62 to the GEIS for Lic Renew of Nuclear Plants IR 05000275/20240132024-10-28028 October 2024 – License Renewal Report 05000275/2024013 and 05000323/2024013 DCL-24-103, Pg&Es Voluntary Submittal of Information Related to 10 CFR 2.206 Petition Regarding Seismic Core Damage Frequency for DCPP, Units 1 and 22024-10-24024 October 2024 Pg&Es Voluntary Submittal of Information Related to 10 CFR 2.206 Petition Regarding Seismic Core Damage Frequency for DCPP, Units 1 and 2 ML24261B9492024-10-24024 October 2024 Issuance of Amendment Nos. 246 and 248 Revision to Technical Specification 5.6.6, Reactor Coolant System (RCS) Pressure and Temperature Limits Report (PTLR) IR 05000275/20244042024-10-23023 October 2024 Security Baseline Inspection Report 05000275/2024404 and 05000323/2024404 ML24277A0292024-10-18018 October 2024 NRC to Fws Req. for Concurrence W. Endangered Species Act Determinations for Diablo Canyon Power Plant Units 1,2, ISFSI Proposed License Renewals in San Luis Obispo Co., CA DCL-24-092, Supplement and Annual Update License Renewal Application, Amendment 12024-10-14014 October 2024 Supplement and Annual Update License Renewal Application, Amendment 1 DCL-24-098, Material Status Report for the Period Ending August 31, 20242024-10-0909 October 2024 Material Status Report for the Period Ending August 31, 2024 DCL-24-091, Response to Request for Additional Information by the Office of Nuclear Reactor Regulation2024-10-0303 October 2024 Response to Request for Additional Information by the Office of Nuclear Reactor Regulation IR 05000275/20253012024-10-0303 October 2024 Notification of NRC Initial Operator Licensing Examination 05000275/2025301; 05000323/2025301 ML24240A0222024-09-20020 September 2024 Letter to A. Peck Environmental Impact Statement Scoping Summary Report for Diablo Canyon Nuclear Power Plant Units 1 and 2 ML24260A1222024-09-14014 September 2024 14 Sept 2024 Ltr - California Coastal Commission to Pg&E, Incomplete Consistency Certification for Requested Nuclear Regulatory Commission License Renewal for Diablo Canyon Power Plant DCL-24-087, License Renewal - Historic and Cultural Resources Reference Documents (Redacted)2024-09-12012 September 2024 License Renewal - Historic and Cultural Resources Reference Documents (Redacted) ML24262A2462024-09-11011 September 2024 10 CFR 2.206 - Diablo Canyon Units 1 and 2 Seismic - Petitioner Response to Acknowledgement Letter - DCL-24-083, CFR Part 21 Notification: Commercially Dedicated Snubber Valve Not Properly Heat Treated2024-09-0909 September 2024 CFR Part 21 Notification: Commercially Dedicated Snubber Valve Not Properly Heat Treated DCL-24-078, Pre-Notice of Disbursement from Decommissioning Trust2024-09-0303 September 2024 Pre-Notice of Disbursement from Decommissioning Trust DCL-24-082, Decommissioning Draft Biological Assessment and Draft Essential Fish Habitat Assessment2024-08-28028 August 2024 Decommissioning Draft Biological Assessment and Draft Essential Fish Habitat Assessment ML24205A0662024-08-27027 August 2024 OEDO-24-00083 - 10 CFR 2.206 - Ack Letter - Diablo Canyon Units 1 and 2 Seismic Core Damage Frequency - IR 05000275/20240052024-08-22022 August 2024 Updated Inspection Plan for Diablo Canyon Power Plant, Units 1 and 2 (Report 05000275/2024005 and 05000323/2024005) DCL-24-077, Responses to NRC Requests for Additional Information on Diablo Canyon Power License Renewal Application Severe Accident2024-08-15015 August 2024 Responses to NRC Requests for Additional Information on Diablo Canyon Power License Renewal Application Severe Accident DCL-24-075, Response to Request for Additional Information for License Amendment Request 23-02, Application to Adopt 10 CFR 50.69, Risk-Informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power React2024-08-0808 August 2024 Response to Request for Additional Information for License Amendment Request 23-02, Application to Adopt 10 CFR 50.69, Risk-Informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power React IR 05000275/20240022024-08-0606 August 2024 Integrated Inspection Report 05000275/2024002 and 05000323/2024002 DCL-24-079, DC-2024-07 Post Exam Comments Analysis2024-08-0202 August 2024 DC-2024-07 Post Exam Comments Analysis DCL-24-070, License Amendment Request 24-03 Revision to Technical Specification 5.5.16 for Permanent Extension of Type a and Type C Leak Rate Test Frequencies2024-07-31031 July 2024 License Amendment Request 24-03 Revision to Technical Specification 5.5.16 for Permanent Extension of Type a and Type C Leak Rate Test Frequencies DCL-24-071, Core Operating Limits Report for Unit 2 Cycle 252024-07-22022 July 2024 Core Operating Limits Report for Unit 2 Cycle 25 DCL-2024-523, Submittal of Report on Discharge Self-Monitoring2024-07-18018 July 2024 Submittal of Report on Discharge Self-Monitoring ML24187A1352024-07-16016 July 2024 Letter to Paula Gerfen - Diablo Canyon Units 1 and 2 - Summary of June 2024 Audit Related to the License Renewal Application Severe Accident Mitigation Alternatives Review IR 05000275/20240142024-07-11011 July 2024 Age-Related Degradation Inspection Report 05000275/2024014 and 05000323/2024014 IR 05000275/20244012024-07-0808 July 2024 Security Baseline Inspection Report 05000275/2024401 and 05000323/2024401 (Full Report) IR 05000323/20240112024-07-0303 July 2024 License Renewal Phase Report 05000323/2024011 DCL-2024-527, Sea Turtle Stranding Report (Loggerhead Sea Turtle) Diablo Canyon Power Plant2024-07-0101 July 2024 Sea Turtle Stranding Report (Loggerhead Sea Turtle) Diablo Canyon Power Plant DCL-24-066, Request to Extend the Nrg Approval of Alternative for Use of Full Structural Weld Overlay, REP-RHR-SWOL2024-06-27027 June 2024 Request to Extend the Nrg Approval of Alternative for Use of Full Structural Weld Overlay, REP-RHR-SWOL ML24155A2182024-06-18018 June 2024 OEDO-23-00350-NRR - (LTR-23-0228-1) - Closure Letter - 10 CFR 2.206 Petition from Mothers for Peace and Friends of the Earth Regarding Diablo Canyon ML24129A1762024-06-14014 June 2024 National Historic Preservation Act Section 106 Consultation – Results of Identification and Evaluation (Docket Number: 72-026) ML24200A2052024-06-0707 June 2024 Fws to NRC, List of Threatened and Endangered Species That May Occur in Your Proposed Project Location or May Be Affected by Your Proposed Project for Diablo Canyon License Renewal ML24099A2192024-05-29029 May 2024 Issuance of Amendment Nos. 245 and 247 Revision to TSs to Adopt TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b ML24117A0132024-05-20020 May 2024 Letter to Paula Gerfen-Diablo Canyon Units 1 and 2-Regulatory Audit Regarding Severe Accident Mitigation Alternatives for the License Renewal Application 2024-09-09
[Table view] Category:Request for Additional Information (RAI)
MONTHYEARML24250A0532024-09-0606 September 2024 LRA - Requests for Additional Information - Set 1 ML24184C0422024-07-0202 July 2024 NRR E-mail Capture - Request for Additional Information Diablo Canyon 50.69 risk-informed Categorization ML24065A1312024-03-20020 March 2024 ISFSI Renewal RAI Transmittal Letter ML24065A1332024-03-20020 March 2024 Enclosure- Diablo Canyon ISFSI Renewal Request for Additional Information ML24024A2072024-01-24024 January 2024 Inservice Inspection Request for Information IR 05000275/20240152023-10-10010 October 2023 – Information Request for the Cybersecurity Baseline Inspection, Notification to Perform Inspection (050002752024015 and 050003232024015) ML23249A2782023-09-0606 September 2023 Inservice Inspection Request for Information ML23159A2372023-07-25025 July 2023 ISFSI Renewal RAI Transmittal Letter Enclosure ML23159A2382023-07-25025 July 2023 Request for Additional Information for the Technical Review of the Application for Renewal of the Diablo Canyon Independent Spent Fuel Storage Installation (Cac/Epid Nos. 001028/L-2022-RNW-0007) ML23096A1792023-04-0606 April 2023 NRR E-mail Capture - Request for Additional Information Diablo Canyon Exemption Request Regarding Senior Reactor Operator License Application ML23047A0062023-02-21021 February 2023 Request for Additional Information Alternative Security Measures for Early Warning System (EPID: L-2022-LLA-0029) (Public Version) ML23041A1862023-02-17017 February 2023 Request for Information Regarding Diablo Canyon Power Plant, Units 1 and 2 - December 8, 2022, Public Meeting ML22258A1112022-09-14014 September 2022 2022 Diablo Canyon PIR Request for Information ML22200A2572022-07-19019 July 2022 Notification of In-service Inspection (Inspection Report 05000323/2022004) and Request for Information ML22187A2652022-07-0606 July 2022 NRR E-mail Capture - Request for Additional Information: Diablo Canyon Exemption Request for Part 73 force-on-force Training Due to COVID-19 ML22152A1502022-06-21021 June 2022 Request for Additional Information Regarding License Amendment Request for Technical Specifications and Revised License Conditions for the Permanently Defueled Condition ML22122A1412022-05-0505 May 2022 .02 Doc Request ML22068A2312022-03-17017 March 2022 Notification of NRC Design Bases Assurance Inspection (Team) 05000275/2022011 and 05000323/2022011 and Initial Request for Information ML22061A2192022-03-0202 March 2022 NRR E-mail Capture - Request for Additional Information - Diablo Canyon Proposed Changes to Emergency Plan for post-shutdown and Permanently Defueled Condition ML21363A1692021-12-29029 December 2021 Inservice Inspection Request for Information ML22019A0412021-12-29029 December 2021 RFI ML21215A3432021-08-0303 August 2021 NRR E-mail Capture - Request for Additional Information - Diablo Canyon Request to Revise Technical Specification 3.8.1, AC Sources - Operating to Support Diesel Fuel Oil Transfer System Component Planned Maintenance ML21130A3642021-06-21021 June 2021 DC 2021401 Information Request ML21104A3642021-04-14014 April 2021 NRR E-mail Capture - Request for Additional Information - Diablo Canyon Proposed Technical Specifications and Revised License Conditions for the Permanently Defueled Condition ML21062A0642021-03-0202 March 2021 NRR E-mail Capture - Request for Additional Information for Diablo Canyon Generic Letter 2004-02 Submittal (L-2017-LRC-0000) ML20329A0692020-11-23023 November 2020 NRR E-mail Capture - Request for Additional Information: Diablo Canyon COVID-19 Exemption Request to Extend force-on-force Exercise ML20323A4532020-11-18018 November 2020 NRR E-mail Capture - Request for Additional Information: Diablo Canyon COVID-19 Exemption Request to Extend Firearms Requalification ML20301A2212020-10-27027 October 2020 Notification of an NRC Fire Protection Baseline Inspection (NRC Inspection Report 05000275/2021010 and 05000323/2021010) and Request for Information ML20261H4232020-09-17017 September 2020 NRR E-mail Capture - Request for Additional Information: Diablo Canyon Unit 2 Fall 2019 Steam Generator Tube Inspection Report ML20231A2372020-08-17017 August 2020 NRR E-mail Capture - Diablo Canyon Additional Request for Additional Information: Exigent License Amendment Request for Application to Provide a New Technical Specification 3.7.5, Auxiliary Feedwater System, Condition G EPID: L-2020-LLA-017 ML20230A0732020-08-14014 August 2020 NRR E-mail Capture - Diablo Canyon Request for Additional Information: Exigent License Amendment Request for Application to Provide a New Technical Specification 3.7.5, Auxiliary Feedwater System, Condition G ML20280A5432020-06-0303 June 2020 DC 2020 PIR Request for Information ML20041E6012020-02-10010 February 2020 NRR E-mail Capture - Diablo Canyon Nuclear Power Plant, Units 1 and 2 - Request for Additional Information for Post -Shutdown Decommissioning Activities Report (PSDAR) ML19262G7482019-08-0909 August 2019 Request for Information ML19149A6012019-05-28028 May 2019 NRR E-mail Capture - Request for Additional Information (Supplemental) - License Amendment Request (LAR) to Revise Emergency Plan Response Organization Staffing and Augmentation ML19123A2162019-05-0202 May 2019 NRR E-mail Capture - Diablo Canyon Nuclear Power Plant -Request for Exemption from Operator Written Examination and Operating Test - Request for Additional Information ML19084A2572019-03-21021 March 2019 NRR E-mail Capture - Request for Additional Information - License Amendment Request (LAR) to Revise Emergency Plan Response Organization Staffing and Augmentation ML19043A9452019-02-20020 February 2019 Notification of Inspection (NRC Inspection Report 05000275/2019002, 05000323/2019002 and Request for Information ML17306A9382017-11-0202 November 2017 NRR E-mail Capture - Request for Additional Information - Request for Approval for Application of Full Weld Overlay REP-RHR-SWOL, Diablo Canyon Power Plant, Units 1 and 2 ML17152A3192017-06-0101 June 2017 NRR E-mail Capture - Request for Additional Information (RAI)- Relief Requests NDE-SLH U2, NDE-LSL U2, NDE-LHC U2, NDE-LHM U2, and NDE-ONV U2 (CAC Nos. MF9386 Through MF9390) ML17102B6072017-04-12012 April 2017 NRR E-mail Capture - Request for Additional Information (RAI) - Revised Emergency Action Level Schemes Pursuant to Nuclear Energy Institute (NEI) 99-01, Revision 6 ML16347A0032016-12-0909 December 2016 NRR E-mail Capture - Request for Additional Information (RAI) - Diablo Canyon Power Plant License Amendment Request for Adoption of NEI 94-01 ML16326A3562016-11-21021 November 2016 NRR E-mail Capture - Request for Additional Information - License Amendment Request to Adopt Nuclear Energy Institute (NEI) 94-01, Revision 2-A for Diablo Canyon Power Plant, Units 1 and 2 - CAC Nos. MF7731 and MF7732 ML16048A2322016-02-17017 February 2016 NRR E-mail Capture - Diablo Canyon 1 and 2 - Met Data Second Round of Requests for Additional Information for License Amendment Request 15-03 to Adopt the Alternative Source Term Per 10 CFR 50.67 (TAC Nos. MF6399 and MF640 ML16011A3652016-02-0202 February 2016 Requests for Additional Information for the Review of the Diablo Canyon Power Plant, Units 1 and 2, License Renewal Application - Set 39 (TAC Nos. ME2896 and ME2897) ML16011A3172016-01-11011 January 2016 NRR E-mail Capture - Diablo Canyon 1 and 2 - Requests for Additional Information for License Amendment Request 15-03 to Adopt the Alternative Source Term Per 10 CFR 50.67 ML15358A0022015-12-23023 December 2015 Request for Additional Information Email (Follow-up Pra), Request to Adopt National Fire Protection Association NFPA 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition) ML15357A3822015-12-23023 December 2015 Request for Additional Information, Round 4 - Amendment Request to Replace Digital Process Protection System for Reactor Protection System and Engineered Safety Features Actuation System Functions ML15295A3732015-11-0505 November 2015 Requests for Additional Information Related to the Diablo Canyon LRA Environmental Review ML15287A1652015-10-23023 October 2015 Requests for Additional Information Related to the Diablo Canyon LRA Environmental Review - SAMA 2024-09-06
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August 1, 2008 Mr. John Conway Senior Vice President - Station Generation and Chief Nuclear Officer Pacific Gas and Electric Company Diablo Canyon Power Plant P.O. Box 770000 San Francisco, CA 94177-0001
SUBJECT:
DIABLO CANYON POWER PLANT, UNITS NOS. 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION REGARDING SUPPLEMENTAL RESPONSE TO GENERIC LETTER 2004-02, "POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY RECIRCULATION DURING DESIGN BASIS ACCIDENTS AT PRESSURIZED-WATER REACTORS" (TAC NO. MD4682 AND MD4683)
Dear Mr. Conway:
By letter dated February 1, 2008 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML080420438), Pacific Gas and Electric Company (PG&E, the licensee) for the Diablo Canyon Power Plant, Units Nos. 1 and 2 (DCPP) submitted a supplemental response to Generic Letter (GL) 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation during Design Basis Accidents at Pressurized-Water Reactors." The NRC staff review of the licensee's submittal was performed by a team of 10 subject matter experts (SME). The detailed review was focused on the areas described in an NRC letter dated November 21, 2007, "Content Guide for Generic Letter 2004-02 Supplemental Responses" (ADAMS Accession No. ML073110389). The review process included a separate "holistic" review of the licensee's submittal, informed by inputs from the SME, that focused on whether the licensee has demonstrated overall that its corrective actions for GL 2004-02 are adequate.
The NRC staff notes that PG&E has been proactive in addressing the issues associated with GL 2004-02. For example, PG&E installed larger ECCS strainers well before GL 2004-02 was issued. In addition, PG&E has performed plant-specific in-vessel downstream effects testing ahead of the Pressurized Water Reactor Owners Group planned testing on the same subject.
However, based on the reviews described above, the NRC staff concluded that additional information is needed for the NRC staff to conclude there is reasonable assurance that GL 2004-02 has been satisfactorily addressed for DCPP. A request for additional information (RAI) is enclosed. The NRC requests the licensee to respond to these RAIs within 90 days of receipt of this letter. If the licensee concludes that more than 90 days is needed to respond to the RAIs, the licensee should request additional time, including a basis for why such time is needed.
If the licensee concludes, based on its review of the RAIs, that additional corrective actions for GL 2004-02 are needed, the licensee should request an extension of time to complete such corrective actions. Criteria for such extensions are contained in SECY-06-0078 (ADAMS Accession No. ML053620174), and many examples of previous requests and approvals can be found on the NRC's sump performance website, http://www.nrc.gov/reactors/operating/ops-experience/pwr-sump-performance.html.
J. Conway In earlier correspondence (ADAMS Accession No. ML070090657 and ADAMS Accession No. ML071010537), the NRC granted PG&E additional time beyond the GL 2004-02 due date of December 31, 2007, to complete specified corrective actions. The NRC understands that the licensee will provide additional results of its GL 2004-02 analyses, including downstream effects components and systems analyses and downstream effects fuel and vessel analyses, in a future GL 2004-02 supplemental response. Given the time frame the licensee evidently plans to submit a final response to GL 2004-02, the NRC staff is open to a reasonable proposal from the licensee that would coordinate its replies to the attached RAIs with its final GL submittal. The NRC staff review of that submittal could result in additional RAIs.
If you or your staff has any questions concerning the resolution of this matter, please contact Alan B. Wang at (301) 415-1445.
Sincerely,
/RA Jack Donohew for/
Alan B. Wang, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-275 and 50-323
Enclosure:
Request for Additional Information cc w/encl: See next page
ML070090657 and ADAMS Accession No. ML071010537), the NRC granted PG&E additional time beyond the GL 2004-02 due date of December 31, 2007, to complete specified corrective actions. The NRC understands that the licensee will provide additional results of its GL 2004-02 analyses, including downstream effects components and systems analyses and downstream effects fuel and vessel analyses, in a future GL 2004-02 supplemental response. Given the time frame the licensee evidently plans to submit a final response to GL 2004-02, the NRC staff is open to a reasonable proposal from the licensee that would coordinate its replies to the attached RAIs with its final GL submittal. The NRC staff review of that submittal could result in additional RAIs.
If you or your staff has any questions concerning the resolution of this matter, please contact Alan B. Wang at (301) 415-1445.
Sincerely,
/RA Jack Donohew for/
Alan B. Wang, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-275 and 50-323
Enclosure:
Request for Additional Information cc w/encl: See next page DISTRIBUTION:
PUBLIC RidsNrrPMAWang Resource RidsOgcRp Resource LPLIV Reading RidsNrrDorlDpr Resource RidsNrrLpl4 Resource RidsRegion4MailCenter Resource RidsNrrDorl Resource RidsAcrsAcnwMailCenter Resource RidsNrrLAGLappert Resource ADAMS Accession Number: ML082050608 OFFICE LPL4/PM LPL4/LA LPL4/BC LPL4/PM NAME AWang J Donohew GLappert MThadani AWang JDonohew for for DATE 8/01/02 8/01/08 8/01/08 8/01/08 OFFICE OF NUCLEAR REACTOR REGULATION REQUEST FOR ADDITIONAL INFORMATION REGARDING SUPPLEMENTAL RESPONSE TO GENERIC LETTER 2004-02 DATED FEBRUARY 2, 2008 DIABLO CANYON POWER PLANT, UNIT NOS. 1 AND 2 DOCKET NOS. 50-275 AND 50-323 By letter dated February 1, 2008 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML080420438), Pacific Gas and Electric Company (PG&E, the licensee) for the Diablo Canyon Power Plant, Units Nos. 1 and 2 (DCPP) submitted a supplemental response to Generic Letter (GL) 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation during Design Basis Accidents at Pressurized-Water Reactors." The NRC staff has reviewed the supplemental response and has determined that we require the following additional information to complete our review:
- 1. Please verify that debris generation values were maximized, in light of the reduced zones of influence (ZOIs) for certain debris sources and the fact that the licensees break selection methodology does not follow the incremental location guidance provided by the Nuclear Energy Institute (NEI) and the NRC staff. Please explain whether the originally applied break selection methodology was reconsidered once the ZOIs were reduced.
- 2. Please provide the basis for comparability/use of the jet impingement testing resulting ZOIs with a 3.5 inch jet when much larger jets could be experienced in a loss-of-coolant accident (LOCA).
- 3. Please provide the volumes of the inactive and sump pools to substantiate the 15%
entrapment fraction of all debris in the inactive pools (i.e., is the volume of inactive pools greater or equal to 15% of total pool volume), and provide the justification for assuming all of the latent debris, instead of being distributed throughout containment, would be located in the sump pool during the pool fill phase, thereby maximizing the credit for latent debris to be captured in inactive pool volumes.
- 4. Please provide the basis for crediting reflective metal insulation (RMI) debris with filtering out paint chips at the debris interceptors in light of the facts that (1) an insufficient amount of RMI for paint chip filtering may be destroyed for some break scenarios for which coating debris is generated, (2) the size distribution of actual destroyed RMI may be biased toward less transportable pieces than assumed by the NEI and NRC staff guidance for debris transport to the sump strainer, and (3) the flow velocity in the pool may not in actuality transport RMI to the interceptors for some of the breaks for which coating debris is generated (i.e., the transport metrics are biased towards maximizing RMI transport to the sump strainers).
- 5. Please state whether the fire stops and unjacketed debris in containment outside the crane wall would be exposed to the runoff of spray drainage streams, and state whether this effect was accounted for in the erosion testing that was performed on these materials (as opposed to assuming that all spray flow was in the form of fine droplets).
- 6. Please provide the amount of each size category of fiber added to each head loss test (e.g., fine, small, large, and intact). Provide a comparison between the amount of each fiber size category added to each test versus the amount of each fiber size category predicted to reach the strainer in the transport calculation. Verify that the fine fibers added to the test flume had not agglomerated during preparation and entered the test flume as suspended fiber.
- 7. Please provide an evaluation that shows that the stirring in the tank to prevent debris settling did not affect the formation of the strainer debris bed in a non-prototypical or non-conservative manner (prevention or wash away of debris beds, or disturbance of the debris bed by non-prototypical intrusion of paint chips or large pieces of fiber).
- 8. Please provide a basis for not performing a time-based extrapolation of the test data out to the emergency core cooling system (ECCS) mission time. [The staff understands that the integrated chemical head loss test was run for the number of fluid turnovers that would occur in the plant. However, there are potential time-based debris bed change mechanisms that could result in additional head loss (e.g., compaction). It has been observed in testing, after many test rig fluid volume turnovers, that after particulate debris has been filtered from the water the strainer head loss continues to increase with time.]
- 9. The supplemental response states that the strainer is completely submerged for a large-break LOCA at the onset of recirculation. However, the supplemental response also states that the top of the strainers are at 93.6 ft and the water level is at 93.4 ft at the onset of recirculation. This implies that the strainer is not fully submerged at the onset of recirculation. Please provide clarification as to whether the strainer is submerged at the onset of recirculation. If it is not, provide an evaluation of the acceptability of the strainer performance under partially submerged conditions.
- 10. The supplemental response states that for a small-break LOCA (SBLOCA) the strainer is not submerged completely. The response describes how the strainers were modified to reduce the potential for vortexing under partially submerged conditions and tested to verify the modifications were effective. However, it was not stated whether strainer testing was completed for partial submergence conditions with the expected debris loading on the strainer. Please provide an evaluation of strainer performance under partially submerged and debris laden conditions. Additionally, provide information that verifies that the clean strainer head loss calculation includes losses associated with the flow straighteners added to prevent vortex formation during SBLOCAs. [Regulatory Guide 1.82, Revision 3 discusses criteria that the strainer should meet under various conditions, including a criterion for allowable head loss for partially submerged strainers.]
- 11. Please provide justification for the computed limiting ECCS flow rate being worst case flow conditions. Please include a description of the methodology used to determine the maximum flow rate (e.g., runout flow from the vendor pump curve, a calculation using a
standard hydraulics code, etc.), as well as a description of the assumptions and the assumed system and component configuration that provides the conservative maximum flow rate (e.g., for single pump operation, can flow cross over to downstream piping in the non-operating train?).
- 12. Please provide a revised table of net positive suction head (NPSH) available and NPSH margin calculation results which does not include clean strainer head loss and head loss from accumulated debris.
- 13. Please verify that the 9.7 g/l AlOOH concentration for the Diablo Canyon settling test shown in the Figure 6 note is correct. The staff notes that the AlOOH precipitate settlement data provided in WCAP-16530-NP was obtained after diluting the various mixing tank concentrations to a 2.2 g/l concentration and that a higher concentration would favor more rapid settling.
Diablo Canyon Power Plant, Units 1 and 2 cc:
NRC Resident Inspector Diablo Canyon Power Plant c/o U.S. Nuclear Regulatory Commission Richard F. Locke, Esq.
P.O. Box 369 Pacific Gas & Electric Company Avila Beach, CA 93424 P.O. Box 7442 San Francisco, CA 94120 Sierra Club San Lucia Chapter ATTN: Andrew Christie City Editor P.O. Box 15755 The Tribune San Luis Obispo, CA 93406 3825 South Higuera Street P.O. Box 112 Ms. Nancy Culver San Luis Obispo, CA 93406-0112 San Luis Obispo Mothers for Peace Mr. Ed Bailey, Chief P.O. Box 164 Radiologic Health Branch Pismo Beach, CA 93448 State Department of Health Services P.O. Box 997414 (MS 7610)
Chairman Sacramento, CA 95899-7414 San Luis Obispo County Board of Supervisors Mr. James D. Boyd, Commissioner Room 370 California Energy Commission County Government Center 1516 Ninth Street (MS 31)
San Luis Obispo, CA 93408 Sacramento, CA 95814 Mr. Truman Burns Mr. James R. Becker, Vice President Mr. Robert Kinosian Diablo Canyon Operations California Public Utilities Commission and Station Director 505 Van Ness, Room 4102 Diablo Canyon Power Plant San Francisco, CA 94102 P.O. Box 3 Avila Beach, CA 93424 Diablo Canyon Independent Safety Committee Jennifer Tang ATTN: Robert R. Wellington, Esq. Field Representative Legal Counsel United States Senator Barbara Boxer 857 Cass Street, Suite D 1700 Montgomery Street, Suite 240 Monterey, CA 93940 San Francisco, CA 94111 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission Harris Tower & Pavillion 612 E. Lamar Blvd., Suite 400 Arlington, TX 76011-4125