RS-07-053, Request for Acceptance for Continuous Extended Power Uprate Operation
| ML071100477 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities  |
| Issue date: | 04/20/2007 |
| From: | Jury K Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, NRC/NRR/ADRO |
| References | |
| RS-07-053 | |
| Download: ML071100477 (6) | |
Text
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[IV RS-07-053 April 20, 2007 U. S. Nuclear Regulatory Commission ATTN : Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-19 and DPR-25 NRC Docket Nos. 50-237 and 50-249 Quad Cities Nuclear Power Station, Units 1 and 2 Renewed Facility Operating License Nos. DPR-29 and DPR-30 NRC Docket Nos. 50-254 and 50-265 Exeloln
Subject:
Request for Acceptance for Continuous Extended Power Uprate Operation Nuclear References :
1. Letter from Keith R. Jury (Exelon Generation Company, LLC) to U.S. NRC, "Commitments and Plans Related to Extended Power Uprate Operations,"
dated January 26, 2006
- 2.
Letter from Kenneth M. Nicely (Exelon Generation Company, LLC) to U. S.
NRC, "Response to Request for Additional Information Related to Extended Power Uprate Operation Commitments," dated October 17, 2006
- 3.
Letter from Patrick R. Simpson (Exelon Generation Company, LLC) to U. S.
NRC, "Technical Documentation Related to Analysis and Design of New Quad Cities Steam Dryers, and Responses to Requests for Additional Information Related to EPU Operation at Dresden and Quad Cities Nuclear Power Stations," dated October 28, 2005
- 4. Letter from Patrick R. Simpson (Exelon Generation Company, LLC) to U. S.
NRC, "Response to Quad Cities Steam Dryer Open Issues," dated December 22, 2005
- 5.
Letter from Patrick R. Simpson (Exelon Generation Company, LLC) to U.S.
NRC, "Additional Information Regarding Quad Cities Unit 2 Steam Dryer Inspection, Start-up and Power Ascension Plan," dated April 27, 2006
April 20, 2007 U. S. Nuclear Regulatory Commission Page 2 6.
Letter from Patrick R. Simpson (Exelon Generation Company, LLC) to U.S.
NRC, "Quad Cities Unit 2 Startup and Power Ascension Testing Following Installation of Acoustic Side Branch Modifications," dated May 3, 2006
- 7. Letter from Kenneth M. Nicely (Exelon Generation Company, LLC) to U. S.
NRC, "Quad Cities Unit 1 Startup and Power Ascension Testing Following Installation of Acoustic Side Branch Modifications," dated August 2, 2006 In Reference 1, Exelon Generation Company, LLC (EGC) updated the regulatory commitments regarding operation of Dresden Nuclear Power Station (DNPS), Units 2 and 3, and Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2, at extended power uprate (EPU) conditions. In accordance with these commitments, EGC met with NRC management on March 22, 2007, to discuss the results and conclusions of evaluations and plant modifications performed to support long-term EPU operation of the QCNPS units. In the March 22, 2007, presentation, EGC summarized the results related to steam dryer replacement, electromatic relief valve (ERV) upgrades, vibration source reduction, and performance monitoring plans at QCNPS.
Additionally, EGC provided a status of the Reference 1 regulatory commitments. Consistent with the Reference 1 commitments and the conclusions of the meeting on March 22, 2007, EGC requests NRC acceptance for continuous operation of the QCNPS units at EPU power levels up to and including the full licensed thermal power level of 2957 megawatts-thermal.
It is EGC's understanding that the NRC will provide a formal response to this request.
This request is the culmination of numerous meetings and interactions between EGC and the NRC related to flow-induced vibration and acoustic loading issues identified following QCNPS initial EPU operation in 2002. Since 2002, EGC has performed extensive evaluations and modifications to improve the structural integrity of susceptible components, as well as to reduce the vibration driving force. The details of these evaluations and modifications have been previously shared with the NRC on several occasions. Following a November 14, 2006, conference call to discuss Reference 2, the NRC stated that the information provided addressed the open technical issues and no further technical information was required.
As detailed in References 3, 4, and 5, and summarized in our presentation on March 22, 2007, the replacement steam dryers and upgraded ERV actuators are designed to withstand the QCNPS bounding vibration and acoustic loads prior to the vibration source reduction effort.
Additionally, the Acoustic Side Branch (ASB) modification has been highly effective in reducing the QCNPS acoustic loads and resulting vibrations to below original licensed thermal power (i.e., pre-EPU) levels (References 6 and 7). The redesigned components, coupled with the ASB effectiveness, significantly increase the components' structural margin and resolve any concerns with QCNPS's ability to operate long-term at EPU power levels.
As a follow-up to NRC requests made during the meeting on March 22, 2007, additional information is provided in the attachments to this letter.
" outlines the remaining committed actions that support operation of the DNPS and QCNPS units at EPU conditions. The commitments in Attachment 1 supersede those described in Reference 1, and represent EGC's remaining commitments in their entirety.
April 20, 2007 U. S. Nuclear Regulatory Commission Page 3
" provides follow-up information in response to NRC questions during the March 22, 2007, meeting.
If you have any questions concerning this request please contact, Mr. David Gullott, at (630) 657-2819.
Keith R. Jury Vice President - Licensing and Regulatory Affairs Attachments: : Summary of Commitments : Meeting Follow-up Information
ATTACHMENT 1 Summary of Commitments The following table identifies commitments being made by Exelon Generation Company, LLC (EGC). Any other actions discussed in this letter represent intended or planned actions by EGC and are described for the NRC's information and are not regulatory commitments.
Commitment Committed Date or Outage 1
During the next scheduled refueling outage on Dresden Nuclear Fall 2007 Power Station (DNPS) Unit 2, EGC will inspect the currently refueling outage installed ERV actuators. EGC will evaluate the results of the for DNPS Unit 2 inspections and determine appropriate actions for the DNPS and Quad Cities Nuclear Power Station (QCNPS) units.
2 Where evaluations or inspections indicate significant potential Spring 2007 degradation of the steam dryer, EGC will take appropriate actions up refueling outage to and including shutting down the applicable unit to conduct for QCNPS Unit 1 inspections or modification on an expedited basis.
During the March 22, 2007, meeting, the NRC asked questions related to the extended power uprate (EPU) monitoring and inspection plans, and limits related to the number of electromatic relief valve (ERV) actuations during operation. The specific follow-up information is provided below.
EPU Monitorina and Inspection Plans ATTACHMENT 2 Meeting Follow-up Information Exelon Generation Company, LLC (EGC) provided the NRC with information related to the EPU monitoring and inspection plans in the referenced letter. This attachment provides additional information regarding these activities.
" EGC will continue to inspect and evaluate the steam dryers at Quad Cities Nuclear Power Station (QCNPS) and Dresden Nuclear Power Station (DNPS) in accordance with the Boiling Water Reactor Vessel Internals Program (BWRVIP) guidance. Presently, General Electric (GE) re-inspection recommendations will be followed for upcoming steam dryer inspections with specific locations identified by GE. The examination techniques used will be in accordance with the requirements of BWRVIP-139, "BWR Vessel and Internals Project Steam Dryer Inspection and Flaw Evaluation Guidelines."
Future steam dryer inspections will be performed in accordance with the guidance of BWRVIP-139, following the addition of re-inspection requirements to a planned revision of BWRVIP-139. EGC continues to monitor and review the revision to BWRVIP-139 and associated NRC comments.
" DNPS and QCNPS Operations currently review and verify once a shift that there are no unexplained changes in steam to feedwater flow, individual steam line flows, and reactor water level and pressure, as well conducting periodic sampling of moisture carryover.
Additionally, DNPS and QCNPS Engineering perform a periodic review of the above parameters, as well as comparisons of the moving averages of main steam line flow, steam to feedwater flow mismatch, and reactor pressure. The performance of future operating parameter reviews and verifications may be changed (e.g., moisture carryover sampling frequency) based on industry guidance, parameter trends, and steam dryer inspection results.
" During the upcoming QCNPS Unit 1 refueling outage in May 2007, one Acoustic Side Branch (AS B)-to-standpipe weld will receive a VT-1 visual examination.
" The ASB-to-standpipe welds are included in the QCNPS Risk-Informed Inservice Inspection (ISI) Program. A sample of the ASB welds have been selected for future volumetric examinations based on a system risk Category 4. The ISI Program directs a volumetric examination of 10 percent of risk Category 4 welds every inspection interval.
There are no volumetric inspections scheduled during the upcoming Unit 1 refueling outage in May 2007. These inspections are scheduled to start during the next refueling outage on QCNPS Unit 2 in February 2008.
" The QCNPS ASB internal inspections, and the ERV cycling, inspections, and actuator/pilot valve replacements discussed in the referenced letter are controlled via the QCNPS Preventive Maintenance Program.
ERV Actuations The purpose of the ASB pre-installation testing was to demonstrate that the operational transients that the ASB could be subject to would not result in loss of ASB function. The testing confirmed ASB performance under expected service conditions, including the impact of several ERV actuations. This testing did not determine a design limit of ERV actuations under which the ASB is qualified. As stated in the referenced letter, any ERV or safety relief valve actuation will prompt additional monitoring of the affected valve and visual examination of the associated ASB internals during the next refueling outage.
Reference ATTACHMENT 2 Meeting Follow-up Information Letter from Kenneth M. Nicely (Exelon Generation Company, LLC) to U. S. NRC, "Response to Request for Additional Information Related to Extended Power Uprate Operation Commitments," dated October 17, 2006