RS-05-123, Commitments and Plans Related to Extended Power Uprate Operation

Commitments and Plans Related to Extended Power Uprate Operation

ML052660483
Person / Time
Site:	Dresden, Quad Cities
Issue date:	09/23/2005
From:	Jury K Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-05-123
Download: ML052660483 (7)

Text

RS-05-123 September 23, 2005 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

Subject:

Commitments and Plans Related to Extended Power Uprate Operation

References:

1 . Letter from K. R. Jury (Exelon Generation Company, LLC) to U. S . NRC, "Commitments for Resolution of Steam Dryer Degradation Issue," dated June 27, 2003

2. Letter from J. A. Benjamin (Exelon Generation Company, LLC) to U . S. NRC, "Commitments and Information Related to Extended Power Uprate," dated April 2, 2004

3. Letter from K. R. Jury (Exelon Generation Company, LLC) to U. S. NRC, "Commitments and Plans Related to Extended Power Uprate Operation,"

dated May 12, 2004 4 . Letter from D. Bost (Exelon Generation Company, LLC) to U. S . NRC, "Commitments and Plans Related to Extended Power Uprate Operation,"

dated December 10, 2004

5. Letter from D. Bost (Exelon Generation Company, LLC) to U. S . NRC, "Revised Commitments and Plans Related to Extended Power Uprate Operation," dated January 31, 2005 6 . Letter from J. A. Benjamin (Exelon Generation Company, LLC) to U . S. NRC, "Commitments and Plans Related to Extended Power Uprate Operation,"

dated May 13, 2005

7. Letter for P . R. Simpson (Exelon Generation Company, LLC) to U . S. NRC, "Clarification of Regulatory Commitments Related to Extended Power Uprate (EPU) Operations," dated June 13, 2005

September 23, 2005 U. S . Nuclear Regulatory Commission Page 2

8. Letter for P. R. Simpson (Exelon Generation Company, LLC) to U . S. NRC, "Commitments and Plans Related to Extended Power Uprate Operation,"

dated July 26, 2005 In the referenced letters, Exelon Generation Company, LLC (EGC) made 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. EGC has completed many of the commitments outlined in the referenced letters through engineering evaluations, inspections, equipment modifications, meetings with the NRC, and submittal of various responses to ?4RC requests for additional information and technical documentation .

EGC completed detailed evaluations of the QCNPS replacement steam dryers in accordance with commitments 9 and 10 of Reference 8, and submitted the results of these evaluations to the NRC . On August 29, through September 1, 2005, EGC met the NRC technical staff to discuss the results and conclusions of these evaluations, and the decision and basis regarding scale model testing of the DNPS steam dryers . Prior to meeting adjournment, the NRC technical staff detailed a list of questions that remain to be resolved with respect to evaluation of the QCNPS steam dryers and their suitability for long-term EPU operation . EGC agreed to address these questions to resolve the issue of steam dryer performance for QCNPS . Based on the schedule for completion of analytical work aimed at addressing the remaining questions, EGC is revising the committed dates for meeting with NRC management and submitting a formal request for returning the affected units to EPU operation as outlined in commitments 12 and 13 of Reference 8.

Further, the NRC provided feedback that EGC should provide a justification and basis for continuing EPU operation of the Quad Cities units while the additional engineering work is completed prior to meeting with NRC management . During the technical meeting held on August 29, through September 1, 2005, EGC provided detailed discussions supporting the operation of the QCNPS units at EPU power levels for both short-term (i .e ., prior to meeting with NRC management) and continuous operation . In summary, the detailed evaluations of the QCNPS replacement steam dryers, using the acoustic circuit model and finite element analysis of derived steam dryer loads, demonstrated that adequate structural margin exists for the replacement steam dryers at all operating conditions, up to and including the full licensed power level of 2957 megawatts-thermal (MWt).

Thermal power levels increased throughout the summer, allowing EGC to collect and evaluate data on the QCNPS units at power levels above those included in startup testing following steam dryer replacement. QCNPS Unit 2 collected steam dryer sensor data at 2907 MWt on June 27, 2005, and achieved a maximum power level of 2918 MWt on July 17, 2005 . QCNPS Unit 1 achieved a maximum power level of 2945 MWt on August 10, 2005. EGC evaluated plant and steam dryer performance, including moisture carryover sample results, at these higher levels power and identified no adverse impacts for continued EPU operation . This further validated the acceptable performance of the steam dryers above the original licensed thermal power level (i.e., 2511 MWt) .

In the short term, thermal power levels on the QCNPS units are expected to decrease as condenser backpressure decreases over the coming weeks due to seasonal variations in circulating water temperature . Therefore, the QCNPS units have operated at their maximum

September 23, 2005 U. S . Nuclear Regulatory Commission Page 3 thermal power levels expected for 2005, with no indication of dryer degradation or EPU extent of condition issues .

EGC performed detailed comparisons of in-plant loads, based on data collected from the installed instrumentation, to the loads used to design the replacement steam dryers . EGC assessed the structural adequacy of the replacement steam dryers using strain gauge data collected on the QCNPS Unit 2 steam dryer. Comparisons of this data to calculated stresses, determined using finite element analysis, provided assurance of the robustness of the replacement dryer design . Given the extensive instrumentation installed on the Unit 2 steam dryer, these evaluations also support the conclusion that adequate loads were used in designing the replacement steam dryers . Further, EGC compared strain gauge data collected on the main steam lines of both QCNPS units. In comparing the Unit 1 strain gauge data to that collected on Unit 2, EGC concluded that the steam dryer loads are similar for both units.

In conclusion, the results of comparisons of implant loads to the design loads, the comparisons of main steam line strain gauge data collected on both units, and the evaluation of the installed strain gauge data from the QCNPS Unit 2 steam dryer, provides EGC with additional confidence in the short-term and long-term structural adequacy of the replacement steam dryers to operate at EPU conditions .

The attachment to this letter outlines the remaining committed actions, as well as our going forward commitments that support operation of the DNPS and QCNPS units at EPU conditions .

The commitments contained in the attachment reflect the status of the QCNPS steam dryer replacement effort, including clarification of commitments addressed in Reference 7. The commitments in the attachment supersede those described in the referenced letters, and represent our commitments in their entirety .

If you have any questions concerning this submittal, phase contact Mr . Thomas G. Roddey, at (630) 657-2811 .

Respectfully, Keith R. Jury Director, Licensing and Regulatory Affairs Attachment : Summary of Commitments

ATTACHMENT 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. They are described for the NRC's information and are not regulatory commitments.

Committed Date Commitment or Outage 1 EGC will continue to conduct daily monitoring of moisture carryover Ongoing and other key reactor and plant parameters while operating at full power at Dresden Nuclear Power Station (DNPS) Units 2 and 3, and Quad Cities Nuclear Power Station (QCNPS) Units 1 and 2, to provide an early indication of potential dryer structural integrity issues . If indications of steam dryer damage or structural integrity concerns are identified, EGC will reduce power at a minimum to the pre-extended power uprate (EPU) level on the affected unit and evaluate and disposition the issue in accordance with the corrective action process.

2 During the next scheduled refueling outage on DNPS Unit 2 and Fall 2005 QCNPS Unit 2, EGC will perform a general visual inspection of the refueling outage reactor pressure vessel internals, steam, and feedwater systems, for DNPS Unit 2 including inspection and disassembly if needed of the most Spring 2006 susceptible components, which include electromatic relief valves .

refueling outage The scope of the inspections will be based upon the results of the for QCNPS EPU vulnerability team effort . If the inspections indicate potential Unit 2 degradation of the reactor pressure vessel internals, steam, or feedwater systems and components, EGC will evaluate and disposition the issue in accordance with the corrective action process. EGC will implement the lessons learned and recommendations from assessment of the vulnerability of other plant equipment to adverse flow effects from EPU operation at DNPS and QCNPS .

3 EGC will attempt to locate and retrieve the lost DNPS Unit 2 Fall 2005 feedwater sample probe . refueling outage for DNPS Unit 2 4 EGC will perform future inspections of the DNPS and QCNPS steam Ongoing dryers using guidance contained in BWRVIP-1 39, "BWR Vessel and Internals Project Steam Dryer Inspection and Flaw Evaluation Guidelines," dated April 2005.

5 EGC will evaluate results of the Fall 2005 DNPS Unit 2 steam dryer Within 30 days of inspection, and determine appropriate action for DNPS Unit 3 . The completing the acceptance criteria will be that no structurally significant cracking is Fall 2005 identified that would limit operation . refueling outage for DNPS Unit 2

ATTACHMENT Committed Date Commitment or Outage 6 EGC will evaluate results of the Spring 2006 QCNPS Unit 2 steam Within 30 days of dryer inspection, and determine appropriate action for QCNPS Unit 1 . completing the The acceptance criteria will be that no structurally significant cracking Spring 2006 is identified that would limit operation . refueling outage for QCNPS Unit 2 7 Where lessons learned from evaluations or inspections conducted Fall 2006 pursuant to commitments described in this letter indicate significant refueling outage potential degradation of the steam dryer, EGC will take appropriate for DNPS Unit 3 actions up to and including shutting down the applicable unit to Spring 2007 conduct inspections or modifications on an expedited basis.

refueling outage for QCNPS Unit 1 8 EGC will meet with the NRC to share the results of the Fall 2005 Within 30 days of DNPS Unit 2 steam dryer inspection, and the impact on, and plans completing the for, DNPS Unit 3. EGC will factor the DNPS Unit 2 inspection results Fall 2005 and analytical work done to date into the decision making process refueling outage related to operating DNPS Unit 3 at EPU power levels and whether a for DNPS Unit 2 appropriate mid-cycle outage is for a steam dryer inspection .

Page 2 of 4

ATTACHMENT Committed Date Commitment or Outage 9 After replacement of the QCNPS Unit 2 steam dryer, operation at During QCNPS EPU power levels will continue while detailed evaluations of the Unit 2 startup, instrumented data are performed, provided the QCNPS Unit 2 within 14 days of Startup Test Plan acceptance criteria (i.e., go/no-go decisions) are EPU operation, met. Operation will be limited to a power level at which acceptance and within 60 criteria are satisfied . Operational and analytical insights/results will days of QCNPS be shared with the NRC on an ongoing basis during periodic Unit 2 data updates. As a minimum, EGC will provide feedback to the NRC on collection at the steam dryer data and other plant instrumentation data and the 930 MWe or the assessment of the design-basis load cases (i .e., including the maximum reactor acoustic circuit and scale models) during the 24-hour hold point at thermal power 2493 MWt, within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of data collection at 930 MWe or the level achieved maximum reactor thermal power level achieved, and within 14 days (Complete) of EPU operation . Detailed evaluations will be performed to compare the predicted QCNPS Unit 2 steam dryer loads, developed using the acoustic circuit model and main steam line strain gauge data, with the actual QCNPS Unit 2 loads obtained from the instrumented steam dryer. EGC will determine whether the assessment of the design-basis load cases at the maximum reactor thermal power level achieved needs to be conducted in a "blind" manner (i .e., similar to the "blind" assessments at lower power levels) and will discuss that determination with the NRC prior to the load determination/blind benchmark . Specific acceptance criteria for the design-basis load cases, including the acoustic circuit and scale models, shall be prepared prior to initiating the assessment of the load cases. The detailed evaluations will be completed and submitted to the NRC within 60 days of data collection at 930 MWe or the maximum reactor thermal power level achieved .

Page 3 of 4

ATTACHMENT 10 After replacement of the QCNPS Unit 1 steam dryer, operation at During QCNPS EPU power levels will continue while detailed evaluations of the Unit 1 startup QCNPS Unit 2 instrumented data are performed, provided the and within 80 QCNPS Unit 1 Startup Test Plan acceptance criteria (i .e., go/no-go days following decisions) are met. Operation will be limited to a power level at reaching full which acceptance criteria are satisfied. Operational and analytical power on with insights/results will be shared the NRC on an ongoing basis QCNPS Unit 1 during periodic updates. EGC will provide the results of the with the validation of the acoustic circuit model based on QCNPS Unit 2 replacement instrumented steam dryer data prior to exceeding 2511 MWt at steam dryer QCNPS Unit 1 . EGC will also provide feedback to the NRC on the installed plant instrumentation data and calculation of the steam dryer loads (Complete) based on the acoustic circuit model prior to exceeding 2511 MWt and within seven days of reaching the maximum reactor thermal power level achieved . Detailed evaluations will be completed and submitted to the NRC within 80 days following reaching full power on QCNPS Unit 1 with the replacement steam dryer installed.

11 EGC will meet with the NRC technical staff to discuss the results Week of and conclusions of evaluations performed pursuant to commitments August 29, 2005 9 and 10 above. EGC will also discuss the decision and basis (Complete) regarding scale model testing of the DNPS steam dryers during this meeting.

11a EGC will meet with the NRC technical staff to discuss the remaining Week of open items identified pursuant to commitment 11 above. November 7, 2005 12 EGC will meet with NRC management to discuss the results and By November 22, conclusions of evaluations performed pursuant to commitments 9 2005 and 10 above. Where NRC management leading the meeting is not with satisfied the results and conclusions of those evaluations, EGC will voluntarily return the affected QCNPS unit(s) to pre-EPU power levels if EGC is unable to resolve those concerns within 14 days .

13 Following resolution of any concerns identified as pat of December 9, commitment 12, EGC will formally request the return of the affected 2005 unit(s) to EPU operation. Where no concerns are identified under commitment 12, EGC will formally request NRC acceptance for continuous EPU operation of the QCNPS units .

Page 4 of 4