RS-12-101, Stations, Units 1 and 2 - Additional Information Supporting Request for License Amendment Regarding Measurement Uncertainty Recapture Power Uprate

Stations, Units 1 and 2 - Additional Information Supporting Request for License Amendment Regarding Measurement Uncertainty Recapture Power Uprate

ML12178A294
Person / Time
Site:	Byron, Braidwood
Issue date:	06/26/2012
From:	Borton K Exelon Generation Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
RS-12-101
Download: ML12178A294 (5)

Text

4300 Winfield Road Warrenville. IL 60555 Exe on GeneratirJn 630 657 2000 Office 10 CFR 50.90 RS-12-101 June 26, 2012 U. S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Facility Operating License Nos. NPF-72 and NPF-77 10 CFR 50.90

1. Letter from Craig Lambert (Exelon Generation Company, LLC) to U. S. NRC, NRC Docket Nos. SIN 50-456 and SIN 50 -457

2. Letter from J. Wiebe (U. S. NRC) to M. J. Pacilio (Exelon Generation

3. Letter from Kevin F. Borton (Exelon Generation Company, LLC) to U. S.

Additional Information Supporting Request for License Amendment Regarding

4. Letter from Kevin F. Borton (Exelon Generation Company, LLC) to U. S.

Byron Station, Units 1 and 2 Facjity Operating License Nos. NPF-37 and NPF-66 NBC Rocket Nos. SIN. 50-454 and SIN. 50-455 630 657 2000 Office Company, LLC), Byron Station, Unit Nos. 1 and 2, and Braidwood Station,

Subject:

Addir~nallnformation Supporting Request for License Amendment Regarding Meas*t.rement Uncerta nty R eQiptiure Power Up rate NRC, "Additional Informat bn Supporting Request for License Amendment Braidwood Station, Units 1 and 2 Byron Station, Units 1 and 2

1. letter from Craig Lambert (Exelon Generation Company, LLC) to u. S. NRC, "Request for License Amendment Regarding Measurement Uncertainty

References:

NRC, 'Additional Information Supporting Request for License Amendment "Request for License Amendmert Regarding Measurement Uncertainty Units 1 and 2 - Request for Additional Information Related to Measurement Recapture (MUR) Power Uprate," dated June 23,201 1 [ML111790030]

2. Letterfrom J. Wiebe (U. S. NRC) to M. J. Pacilio (Exelon Generat'on Company, LLC), "Byron Station, Unit Nos. 1 and 2, and Braidwood Station, Regarding Measurement Uncertainty Recapture Power Uprate," dated May Meas urement Uncerta inty Recapt ure Power Uprate Units 1 and 2 - Request for Additiona I Information Related to Measurement Uncertainty Recapture Uprate (TAC Nos. ME6587, ME6588, ME6589, and Facility Operating License Nos. NPF-72 and NPF-77 Faciity Operating License Nos. NPF -37 and NPF-66 ME6590)," dated June 13 , 2012 [ML12157A063]

E eLonGenerrtbn Uncertainty Recapture Uprate (TAC Nos. ME6587, ME6588, ME6589, and

3. Letter from Kevin F. Borton (Exelon Generation Company, LLC) to u. S.

NRC, "Additional Informatbn Supporting Request for License Amendment Recapture (MUR) Power Uprate," dated June 23, 2011 [ML111790030]

U. S. Nuclear Regulatory Commission Regarding Measurement Uncertainty Recapture Power Uprate," dated Regarding Measurement Uncertainty Recapture Power Uprate,* dated May 16,2012 [ML12138A091]

16, 2012 [ML12138A091 ]

4. Letter from Kevin F. Borton (Exelon Generation Company, LLC) to u. S .

NRC Docket Nos. STN 50-456 and SIN 50-457 NRC Docket Nos. STN 50-454 and STN 50-455 ME6590)," dated June 13.2012 [ML12157A063]

NRC, 'Additionallnformation Supporting Request for License Amendment Regarding Measurement Uncertainty Recapture Power Uprate, II dated ATTN: Document Control Desk March 30, 2012 In Reference 1, Exelon Generation Company, LLC (EGC) requested an amendment to Faclity Operating License Nos. NPF-72, NPF-77, NPF-37 and NPF-66 for Braidwood Station, Unls 1 June 26, 2012 and 2, and Byron Station, Units 1 and 2, respectively. Specifically, the p'roposed changes revise

References:

the Operating License and Technical Specifications to implement an increase in rated thermal RS-12-101 Washington, DC 20555-0001 power of approximately 1.63% based on increased feedwater flow measurement accuracy.

Subject:

.demM

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June 26, 2012 U.S. Nuclear Regulatory Commission Page 2 The requested information in Reference 2 regarding the Spent Fuel Pool (SFP) rebar stresses 's provided in Attachment 1 to this letter. The requested information provides additional detail to

_ information ~reviousl~ ~rovided by EGC to the NRC in References 3 and 4. As noted in

---

Reference 2, thIS-lnformation-wasdlsclJssed with the NRC-Ciurlng-a conference calTOnMay -23,------------------

2012.

EGC has rev'l8wed the information support'ng a finding of no significant hazards considerat'1!) n 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 for concluding that the proposed license amendment does not involve a Significant hazards consideration in Reference 1. In addition, the information provided in this submittal does not affect the bases br concluding that neither an environmental impact statement nor an environmental assessment needs to be prepared in connection with the proposed amendment.

The requested information in Reference 2 regarding the Spent Fuel Pool (SFP) rebar stresses 'e EGC has reviewed the information support'ng a finding of no significant hazards consideratb n There are no regulatory commitments contained in this letter.

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

I declare under pena Ity of perjury that the foregoing is true and correct. Executed on the I declare under pena~ of perjury that the foregoing is true and correct. Executed on the Response to Request for Additional Information, NRC Letter dated 26th day of June 2012 .

and the environmental consideration provided to the NRC in Reference 1. The additional Respectfully, provided in Attachment 1 to this letter. The requested information provides additional detail to information provided in this submittal does not affect the previously stated bases for concluding Kevin F. Borton Manager, Licensing - Power Uprate

`There are no regulatory commitments contained in this letter.

information previously provided by EGC to the NRC in References 3 and 4. As noted in Attachment 1 Response to Request for Additional Information, NRC Letter dated that the proposed license amendment does not involve a significant hazards consideration in June 13, 2012, (Non-Proprietary) [ML12157A063]

June 13, 2012, (Non-Proprietary) [ML12157A063]

Reference 1. In addition, the information provided in this submittal does not affect the bases br (630) 657-3316.

June 26, 2012 261h day of June 2012.

Reference 2, this information was discussed with the NRC during a conference call on May 23, Kevin F. Borton U.S. Nuclear Regulatory Commission concluding that neither an environmental impact statement nor an environmental assessment 2012. needs to be prepared in connection with the proposed amendment. Respectfully, Manager, Licensing - Power Uprate Attachment 1 Page 2

ATTACHMENT I RESPONSE TO REQUEST FOR RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION NRC Letter dated June 13, 2012

[ML12157A063] ADDITIONAL INFORMATION (NON-PROPRIETARY)

NRC letter dated June 13,2012 ATTACHMENT 1 (NON-PROPRIETARY)

[Ml12157A063]

NRC Request 1 Exelon's letter, dated May 16, 2012, in response to the NRC's letter dated May 10,2012, references the NRC safety evaluation (SE) for stretch power uprate, dated May 4,2001.

In this NRC SE for stretch power uprate, it is stated that the licensee performed an analysis of the spent fuel pool (SFP) structure that confirmed the maximum rebar stress of 53. 7 ksi for the maximum bulk pool temperature of 162. 7°F to be within the allowable limit of 54 ksi.

Exelon's letter, dated May 16, 2012, states that a detailed evaluation of the SFP structure for a bounding temperature of 167°F resulted in a maximum rebar stress of 30.3 ksi.

During a May 23, 2012, conference call to clarify why the rebar stress is now significantly less than that provided in 2001, Exelon provided information not included in previous submittals to explain the reason for the reduction in stress.

(1) Submit the explanation for the significant reduction in rebar stress from 53.7 ksi During a May 23, 2012, conference call to clarify why the rebar stress is now significantly to 30.3 ksi. The response, as a minimum, should include the description of the Exelon's letter, dated May 16, 2012, in response to the NRC's letter dated May 10, 2012, The Measurement Uncertainty Recapture (MUR) power uprate evaluation of the Submit the explanation for the significant reduction in rebar stress from 53.7 ksi Confirm that the detailed evaluation for the MUR condition is consistent with the methodology and parameters used in the MUR evaluation that are different from Exelon's letter, dated May 16, 2012, states that a detailed evaluation of the SFP those used in the evaluation performed for the stretch power uprate and an explanation how these differences affect the rebar stress calculation; effects of spent fuel pool (SFP) peak temperature on rebar stresses used the same (2) Confirm that the detai/ed evaluation for the MUR condition is consistent with the methodo bgy and governing load combinations as the previous evaluations, but plant licensing basis, including Section 3.8.4 of the Byron and Braidwood references the NRC safety evaluation (SE) for stretch power uprate, dated May 4, 2001.

updated final safety analysis report. eliminated an unnecessary conservatism in applying the thermal moment due to to 30.3 ksi. The response, as a minimum, should include the description of the Response axial temperature increase. In previous evaluations, including the stretch power (1) The Measurement Uncertainty Recapture (MUR) power uprate evaluation of the effects of spent fuel pool (SFP) peak temperature on rebar stresses used the same uprate (References Al-1 and 2), the TEMCO computer program was used to plant licensing basis, including Section 3.8.4 of the Byron and Braidwood In this NRC SE for stretch power uprate, it is stated that the licensee performed an methodo bgy and governing load combinations as the previous evaluations, but consider the effect of the redistribution of thermal stresses on the thermal moments less than that provided in 2001, Exelon provided information not included in previous structure for a bounding temperature of 167°F resulted in a maximum rebar stress of eliminated an unnecessary conservatism in applying the thermal moment due to methodology and parameters used in the MUR evaluation that are different from axial temperature increase. In previous evaluations, including the stretch power uprate (References A1-1 and 2), the TEMCO computer program was used to due to temperature gradient effects that resulted from section cracking* . The consider the effect of the redistribution of thermal stresses on the thermal moments due to temperature gradient effects that resulted from section cracking* . The thermal moment induced by the axial temperature increase was conservatively analysis of the spent fuel pool (SFP) structure that confirmed the maximum rebar stress thermal moment induced by the axial temperature increase was conservatively treated as a mechanical moment. This was an unnecessary conservative treated as a mechanical moment. This was an unnecessary conservative those used in the evaluation performed for the stretch power uprate and an assumption since thermal moments are not mechanical loads and the resulting stresses would be reduced/relieved due to allowed modeling of concrete cracking. assumption since thermal moments are not mechanical loads and the resulting For the MUR power uprate evaluation, the thermal moment due to axial stresses would be reduced/relieved due to allowed modeling of concrete cracking.

updated final safety analysis report.

temperature increase was converted to an equivalent thermal gradient and applied of 53.7 ksi for the maximum bulk pool temperature of 162.7°F to be within the allowable to the TEMCO program. Removing this unnecessary conservatism resulted in the For the MUR power uprate evaluation, the thermal moment due to axial submittals to explain the reason for the reduction in stress.

reduction in the rebar stresses postulated in the TEMCO program.

30.3 ksi.

temperature increase was converted to an equivalent thermal gradient and applied explanation how these differences affect the rebar stress calculation; (2) The MUR power uprate evaluation for the SFP is consistent with the plant licensing basis requirements described in the applicable portions of UFSAR Secfon 3.8.4, NRC Request I spec*tically, the use of the design baSIS loading combinahms and the use of Uhe to the TEMCO program. Removing this unnecessary conservatism resulted in the limit of 54 ksi. Response reduction in the rebar stresses postulated in the TEMCO program.

• Redistribution of thermal stresses as a result of sectbn cracking (1) (2) is cons-'lSte rt w t h AC I 349 Appendix A. "Thermal Considerations."

(1)

TEMCO computer program for evaluating the stress in the SFP reinforced concrete structure as described in Section 3.8.4.4. A1-1 A1-2

REFERENCES:

Al-1 Letter from R. M. Krich (Exebn Generation Company, LLC) to U. S. NRC,

REFERENCES:

"Response to Request for Additional Informatbn Regarding the License Amendment Request to Permit Uprated Power Operations at Byron and Letter from R. M. Krich (Exe'bn Ge'~ration Company, LLC) to U. S. NRC, Braidwood Stations," Letter RS-00-158 , dated December 21, 2000 Letter from U. S. NRC to Mr. O. D. Kingsley (Exelon Generation Company, LLC),

[ML003780801 ].

Al-2 Letter from U. S. NRC to Mr. O. D. Kingsley (Exelon Generation Company, LLC),

"Issuance of Amendments; Increase in Reactor Power, Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 (TAC Nos . MA9428, MA 9429, "Response to Request for Additional Informatbn Regarding the License MA9426, and MA9427)," May 4, 2001 [ML011420274].

TEMCO computer program for eV8Iuating the stress in the SFP reinforced concrete "Issuance of Amendments; Increase in Reactor Power, Byron Station, Units 1 Amendment Request to Permit Uprated Power Operations at Byron and and 2, and Braidwood Staton, Units 1 and 2 (TAC Nos

• MA9428, MA 9429, Braidwood Stations," Letter RS-00-158 , dated December 21, 2000 (ML003780801 ].

MA9426, and MA9427)," May 4,2001 [ML011420274].

structure as described in Section 3.8.4.4.