ML081780786
| ML081780786 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 06/27/2008 |
| From: | Mahesh Chawla NRC/NRR/ADRO/DORL/LPLIII-1 |
| To: | Entergy Nuclear Operations |
| Chawla M, NRR/DORL, 415-8371 | |
| References | |
| GL-04-002, TAC MC4701 | |
| Download: ML081780786 (8) | |
Text
June 27, 2008 Vice President, Operations Entergy Nuclear Operations Palisades Nuclear Plant 27780 Blue Star Memorial Highway Covert, MI 49043-9530
SUBJECT:
PALISADES NUCLEAR PLANT - GENERIC LETTER 2004-02 POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY RECIRCULATION DURING DESIGN-BASIS ACCIDENTS AT PRESSURIZED-WATER REACTORS EXTENSION REQUEST APPROVAL (TAC NO. MC4701)
Dear Sir or Madam:
The Nuclear Regulatory Commission (NRC) staff has evaluated the information provided in the Entergy Nuclear Operations, Inc. (ENO) letter dated June 17, 2008 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML081690612), and an e-mail from Ms. Laurie Lahti of ENO dated June 19, 2008 (ADAMS Accession No. ML081710478),
supporting a request for an extension of the Palisades Nuclear Plant (PNP) sump clogging corrective actions due date of December 31, 2008, stated in Generic Letter (GL) 2004-02 Potential Impact of Debris Blockage on Emergency Recirculation During Design-Basis Accidents at Pressurized-Water Reactors, to June 30, 2008.
The NRC staff believes that ENO has a reasonable plan for PNP that should result in the completion of final GL 2004-02 corrective actions that provide acceptable strainer function with adequate margin for uncertainties. The additional time requested in ENOs June 17, 2008, letter, is considered to be of low safety concern given the mitigative measures and plant improvements already in place. Based on ENO having satisfactorily addressed the NRC GL 2004-02 due date extension criteria as discussed in the enclosed evaluation, the NRC staff finds it is acceptable to extend the completion date for GL 2004-02 corrective actions associated with strainer performance testing, final analysis and related licensing activities, as described in this enclosure to December 31, 2008. The NRC also accepts ENOs commitment to complete modifications needed to fully resolve GSI-191 prior to restart from the 2009 refueling outage as appropriate and timely considering remaining work to be done as discussed in ENOs June 19, 2009, e-mail.
If you have any questions, please do not hesitate to call me at 301-415-8371.
Sincerely,
/RA/
Mahesh L. Chawla, Project Manager Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-255
Enclosure:
Staff Evaluation cc w/encls: See next page
If you have any questions, please do not hesitate to call me at 301-415-8371.
Sincerely,
/RA/
Mahesh L. Chawla, Project Manager Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-255
Enclosure:
Staff Evaluation cc w/encls: See next page DISTRIBUTION PUBLIC LPL3-1 R/F RidsOgcRp RidsNrrDorlLpl3-1 RidsAcrsAcnw&mMailCenter RidsNrrPMMChawla RidsNrrDssSsib RidsNrrLATHarris RidsRgn3MailCenter LWhitney, NRR JGolla, NRR E. Geiger, NRR ADAMS Accession Number: ML081780786 OFFICE LPL3-1/PM LPL3-1/LA DSS/SSIB/BC LPL3-1/BC NAME MChawla THarris MScott PTam for LJames 06/25/08 DATE 6/27/08 6/27/08 6/27/08
- Memo of 6/26/08 OFFICIAL RECORD COPY
EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION APPROVAL OF EXTENSION REQUEST GENERIC SAFETY ISSUE-191/GENERIC LETTER 2004-02 PALISADES NUCLEAR PLANT DOCKET NO. 50-255 By letter dated June 17, 2008 (Agencywide Document Access and Management System (ADAMS) Accession No. ML081690612), Entergy Nuclear Operations (ENO), the licensee, requested an extension to the current Nuclear Regulatory Commission (NRC) Generic Letter (GL) 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design-Basis Accidents at Pressurized-Water Reactors corrective action due date of June 30, 2008, for Palisades Nuclear Plant. The stated intent of this extension was to allow ENO additional time to complete: (1) in-vessel downstream effects evaluations per (draft) WCAP-16793-NP Evaluation of Long-term Cooling Associated with Sump Debris Effects, Revision 1; (2) revision to the ex-vessel downstream effects evaluations to address WCAP-16406-P, Evaluation of Downstream Sump Debris Effects in Support of GSI-191, Revision 1; (3) strainer head loss and chemical effects testing and evaluation of test results; and (4) determination of whether hardware and/or procedural modifications are needed as a result of the chemical effects testing and evaluation, and implementation of modification or modifications, if required. The requested due date extension is a restart from the 2009 refueling outage, currently scheduled to begin March 22, 2009.
ENO stated that it would re-evaluate its in-vessel downstream effects results against the final WCAP-16793-NP, Evaluation of Long-Term Cooling Considering Particulate, Fibrous and Chemical Debris in the Recirculating Fluid, and the final NRC safety evaluation (SE) of the same, when these two documents are issued.
In a June 19, 2008, e-mail (ADAMS Accession No. ML081710478), ENO stated that strainer head loss and chemical effects testing was scheduled to be reconvened at Alden Research Laboratory on September 15, 2008. ENO stated that the planned testing would reflect contingency modifications that are being developed in parallel, examples being removal of up to 100 percent of fiber insulation, installation of debris interceptors, and installation of additional strainers. ENO stated that incorporation of modifications into the test parameters for the September 15, 2008, testing was expected to avoid the need for future testing iterations and would provide assurance that the GSI-191 issue would be addressed no later than restart from the 2009 refueling outage.
ENO further stated in its June 19, 2008, e-mail, that its recent replacement of trisodium phosphate with sodium tetraborate as the containment sump buffering agent was a permanent modification under License Amendment No. 227 issued by the NRC on October 2, 2007 (ADAMS Accession No. ML07250735).
The NRC has based its reviews for granting extensions to the due date for completion of GL 04-02 corrective actions on the criteria stated in SECY-06-0078. Specifically, an extension may be granted if:
- the licensee has a plant-specific technical/experimental plan with milestones and schedule to address outstanding technical issues with enough margin to account for uncertainties, and
- the licensee identifies mitigative measures to be put in place prior to December 31, 2007, and adequately describes how these mitigative measures will minimize the risk of degraded emergency core cooling system (ECCS) and containment spray system (CSS) functions during the extension period.
SECY-06-0078 also stated that for proposed extensions beyond several months, a licensees request will more likely be accepted if the proposed mitigative measures include temporary physical improvements to the ECCS sump or materials inside containment to better ensure a high level of ECCS sump performance.
With regard to the first extension criterion, ENO has provided a plant-specific technical/experimental plan, with milestones and schedules, to complete the GL 2004-02 corrective actions. Specifically, in its June 17, 2008, letter, ENO referenced its August 25, 2005, May 12, 2006, and July 18, 2006, supplemental responses to GL 2004-02 (ADAMS Accession Nos. ML052500280, ML061320249, and ML061990310, respectively) to provide a summary of key actions and current status:
(1) Completed Actions (a) Debris generation, debris transport, and downstream effects calculations and evaluations.
(b) Strainer debris head loss testing.
(c) Strainer bypass testing.
(d) Installation of sump passive strainers.
(e) Replacement of CSS isolation valves.
(f) Replacement of high-pressure safety injection pumps seals and seal coolers.
(g) Replacement of trisodium phosphate buffer with sodium tetraborate.
(h) Generic chemical effects strainer test protocol developed by strainer vendor (Performance Contracting, Inc).
(2) Actions in Progress (a) Develop computational fluid dynamics and test inputs for subsequent chemical effects strainer testing.
(b) Reevaluate downstream effects to incorporate WCAP-16406-P, Revision 1, scheduled for completion in third quarter of 2008.
(c) Complete an analysis of the downstream effects on the fuel per WCAP-16793-NP, scheduled for completion in third quarter of 2008. ENO plans to assess the Palisades Nuclear Plant specific evaluation for impact when the final NRC SE is issued on the final WCAP-16793-NP.
(3) Planned Actions (a) Complete chemical effects strainer testing by September 30, 2008.
(b) Complete strainer debris and chemical effects test report including supporting analyses for testing and inputs by December 31, 2008.
(c) Complete any necessary modifications prior to restart from the 2009 refueling outage.
(d) Complete design and license bases updates, and provide final update to GL 2004-02 supplemental response by February 27, 2009, if no modification is required, or 60 days following completion of the 2009 refueling outage if modification is required.
With regard to the second extension criterion, ENO stated that it has put in place the following mitigative measures that minimize the risk of degraded ECCS and CSS functions during the extension period:
(1) During the 2007 refueling outage, the original containment sump screens (approximately 52 ft2) were replaced. The replacement strainers are a modular design and have a surface area of approximately 3500 ft2. The previous sump screens consisted of 0.047" diameter wire on 0.125" square center spacing. The new strainers consist of 0.045" diameter hole perforated plate. These strainers were designed to minimize fiber debris bypass to reduce downstream effects, and to provide a substantial increase in available strainer surface area. The new strainers provide increased margin against blockage and excessive wear of downstream components due to debris in the water.
(2) During the 2007 refueling outage, the containment spray valves were replaced with a new design that automatically repositions to a throttle position at initiation of containment sump recirculation.
(3) During the 2007 refueling outage, the previous containment trisodium phosphate buffer was replaced with sodium tetraborate. This modification eliminated the potential calcium phosphate chemical effects concern.
(4) During the 2007 refueling outage, the mechanical seal system for the high-pressure safety injection (HPSI) pumps was replaced with a mechanical seal system that is not susceptible to post-loss-of-coolant accident (LOCA) debris-induced failure. This ensures that the HPSl pumps are capable of performing their safety-related design function during their required mission time of 30 days under post-LOCA conditions.
(5) Mitigative measures in response to NRC Bulletin 2003-01, Potential Impact of Debris Blockage on Emergency Sump Recirculation at Pressurized-Water Reactors, are in place and continue to be in effect and include implementation of compensatory measures including candidate operator actions, as described in WCAP-16204, "Evaluation of Potential ERG [Emergency Response Guideline] and EPG [Emergency Procedure Guideline] Changes to Address NRC Bulletin 2003-01 Recommendations."
By letter dated August 14, 2003 (ML032230019), the NRC provided notification that the 60-day response actions for compensatory measures that have been, or will be, implemented to reduce the interim risk associated with potentially degraded or nonconforming ECCS and CSS recirculation functions, are considered complete for Palisades Nuclear Plant.
In addition to the above mitigative measures, ENO stated that it had: (1) established programmatic controls that ensure that materials that are introduced to containment are identified and evaluated to determine if they could affect sump performance or lead to downstream equipment degradation; (2) established programmatic controls that ensure that configuration control of insulation and coatings inside containment are maintained; and (3) assured containment cleanliness through procedural controls.
The NRC staff believes that the approximately 3500 ft2 of replacement strainers and containment sump pool pH buffer replacement meet the criterion relating to temporary physical improvements to the ECCS sump or materials inside containment to better ensure a high level of ECCS sump performance.
The NRC staff believes that ENO has a reasonable plan for Palisades Nuclear Plant that should result in the completion of final GL 2004-02 corrective actions that provide acceptable strainer function with adequate margin for uncertainties. The additional time requested in ENOs June 17, 2008, letter, is considered to be of low safety concern given the mitigative measures and plant improvements already in place. Based on the licensee having satisfactorily addressed the NRC GL 2004-02 due date extension criteria as discussed above, the NRC staff finds it is acceptable to extend the completion date for GL 2004-02 corrective actions associated with strainer performance testing, final analysis and related licensing activities, as described in this enclosure to December 31, 2008. The NRC also accepts ENOs commitment to complete modifications needed to fully resolve GSI-191 prior to restart from the 2009 refueling outage as appropriate and timely considering remaining work to be done as discussed in ENOs June 19, 2009, e-mail.
Principal Contributor: L. Whitney, NRR Date: June 27, 2008
Palisades Plant cc:
Supervisor Senior Vice President and COO Covert Township Entergy Nuclear Operations P. O. Box 35 440 Hamilton Avenue Covert, MI 49043 White Plains, NY 10601 Office of the Governor Assistant General Counsel P. O. Box 30013 Entergy Nuclear Operations Lansing, MI 48909 440 Hamilton Avenue White Plains, NY 10601 U.S. Nuclear Regulatory Commission Resident Inspector's Office Manager, Licensing Palisades Plant Entergy Nuclear Operations 27782 Blue Star Memorial Highway Palisades Nuclear Plant Covert, MI 49043 27780 Blue Star Memorial Highway Covert, MI 49043-9530 Michigan Department of Environmental Quality Waste and Hazardous Materials Division Radiological Protection Section Radiological Assessment Unit Constitution Hall, Lower-Level North 525 West Allegan Street P.O. Box 30241 Lansing, MI 48909-7741 Michigan Department of Attorney General Special Litigation Division 525 West Ottawa St.
Sixth Floor, G. Mennen Williams Building Lansing, MI 48913 Senior Vice President Entergy Nuclear Operations P. O. Box 31995 Jackson, MS 39286-1995 Vice President Oversight Entergy Nuclear Operations P. O. Box 31995 Jackson, MS 39286-1995 Senior Manager, Nuclear Safety
& Licensing Entergy Nuclear Operations P. O. Box 31995 Jackson, MS 39286-1995 June 18, 2008