RS-12-144, Additional Information Supporting Request for License Amendment Regarding Measurement Uncertainty Recapture Power Uprate

Additional Information Supporting Request for License Amendment Regarding Measurement Uncertainty Recapture Power Uprate

ML12258A330
Person / Time
Site:	Byron, Braidwood
Issue date:	09/13/2012
From:	Borton K Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-12-144, TAC ME6587, TAC ME6588, TAC ME6589, TAC ME6590
Download: ML12258A330 (5)

Text

4300 Winfield Road 1

Warrenville. IL 60555 Exelon Generation, 630 657 2000 Office 10 CFR 50.90 RS-12-144 September 13, 2012 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457 Byron Station, Units 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455

Subject:

Additional Information Supporting Request for License Amendment Regarding Measurement Uncertainty Recapture Power Uprate

References:

1. Letter from Craig Lambert (Exelon Generation Company, LLC) to U. S. NRC, "Request for License Amendment Regarding Measurement Uncertainty Recapture (MUR) Power Uprate," dated June 23, 2011 [ML111790030]

2. Letter from J. Wiebe (U. S. NRC) to M. J. Pacilio (Exelon Generation Company, LLC), "Byron Station, Unit Nos. 1 and 2, and Braidwood Station, Units 1 and 2 - Request for Additional Information Related to License Application for Measurement Uncertainty Recapture Uprate (TAC NOS. ME6587, ME6588, ME6589, and ME6590)," dated August 27, 2012 [ML12233A601]

In Reference 1, Exelon Generation Company, LLC (EGC) requested an amendment to Facility Operating License Nos. NPF-72, NPF-77, NPF-37 and NPF-66 for Braidwood Station, Units 1 and 2, and Byron Station, Units 1 and 2, respectively. Specifically, the proposed changes revise the Operating License and Technical Specifications to implement an increase in rated thermal power of approximately 1.63% based on increased feedwater flow measurement accuracy.

In Reference 2 the NRC has requested additional information (RAI) to support review of the proposed changes within 30 days of August 27 ,2012. The response to this RAI is provided in the Attachment to this letter.

EGC has reviewed the information supporting a finding of no significant hazards consideration and the environmental consideration provided to the NRC in Reference 1.

The additional information provided in this submittal does not affect the previously stated bases in Reference 1 for concluding that the proposed license amendment does not involve a significant hazards consideration. In addition, the information provided in this submittal does not affect the bases for concluding that neither an environmental impact

September 13, 2012 U.S. Nuclear Regulatory Commission Page 2 statement nor an environmental assessment needs to be prepared in connection with the proposed amendment.

There are no regulatory commitments contained in this letter.

Should you have any questions concerning this letter, please contact Leslie E. Holden at (630) 657-3316.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 13th day of September 2012.

Respectfully, Kevin F. Borton Manager, Licensing - Power Uprate Attachment Response to Request for Additional Information, NRC Letter dated August 27, 2012 [ML12233A601], (Non-Proprietary)

ATTACHMENT RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION NRC Letter dated August 27, 2012

[ML12233A601]

(NON-PROPRIETARY)

Braidwood/Byron Stations MUR LAR Response to RAI September 13, 2012 Attachment, page 1 NRC Request EGCs supplemental submittal dated May 16, 2012, states:

The SFP [spent fuel pool] liner and racks were evaluated in the existing analyses of record for a design temperature of 200°F [degrees Fahrenheit],

which bounds the peak MUR SFP temperature of 166.6°F.

Page 9.1-29 of the Byron and Braidwood updated final safety analysis report (UFSAR) states:

The liner plate and anchorage system have been designed for the forces resulting from long-term shrinkage of concrete, and a temperature rise to 158°F from the 70°F ambient temperature with nominal cooling.

The design temperature for the liner (158°F) in the UFSAR and the temperature noted in the response to RAI-13 in your May 16, 2012 submittal (200°F), do not appear to be consistent. Please clarify the statement in EGCs May 16, 2012, submittal.

Response

Based on a review of the Braidwood and Byron design basis, there were three separate analyses that address the loads on the Spent Fuel Pool (SFP):

1) Structural - This analysis assesses the SFP structure for flexure, shear loads and moment loads on the reinforcing steel. This analysis was described in the May 16, 2012 RAI response (Reference A-1). As discussed in that response, this analysis was re-performed at 167°F for the Measurement Uncertainty Recapture (MUR) power uprate, which bounds the peak MUR SFP temperature of 166.6°F.

2) Liner Integrity - This analysis assesses the adequacy of the SFP liner and the racks. The liner was analyzed for loads from the spent fuel racks and the Safe Shutdown Earthquake (SSE). Clarifying our May 16, 2012 response (Reference A-1), this analysis assumed the limiting liner material properties at 200°F. This analysis was performed when the SFP was re-racked and was the analysis of record (AOR) for the SFP liner integrity. The liner anchorage system was not included within the scope of this analysis.

Since the 200°F temperature used in this analysis bounded the MUR power uprate maximum SFP temperature of 166.6°F this value was reported in the May 16, 2012 response (Reference A-1).

3) Liner and Anchorage System - This is the analysis that is referenced in the RAI wording from UFSAR Section 9.1.2.3.10, Fuel Rack Design Features. This was a separate evaluation of the SFP liner and anchorage system to assess the forces resulting from the differential expansion between the liner and the anchorage due to thermal expansion and buckling.

For consistency, the SFP design basis was recently reconstituted assuming a SFP temperature of 167°F. As part of this reconstitution, both the Liner Integrity and Liner and Anchorage System analyses discussed above were re-performed using a temperature of 167°F and the results demonstrate acceptable stresses at MUR power uprate conditions. The reconstituted analyses supersede the previous SFP analyses. The UFSAR will be updated to reflect these changes.

Braidwood/Byron Stations MUR LAR Response to RAI September 13, 2012 Attachment, page 2

REFERENCE:

A-1. Letter from Kevin F. Borton (Exelon Generation Company, LLC) to U. S. NRC, "Additional Information Supporting Request for License Amendment Regarding Measurement Uncertainty Recapture Power Uprate," dated May 16, 2012

[ML12138A091]