RS-17-048, Annual 10 CFR 50.46 Report of Emergency Core Cooling System Evaluation Model Changes and Errors

Annual 10 CFR 50.46 Report of Emergency Core Cooling System Evaluation Model Changes and Errors

ML17097A205
Person / Time
Site:	Byron, Braidwood
Issue date:	04/07/2017
From:	Gullott D Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-17-048
Download: ML17097A205 (20)

Text

4300 Winfield Road Warrenville, IL 60555 eAmmommoK ExeLon G 630 657 2000 Office RS-17-048 10 CFR 50.46 April 7, 2017 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and 50-457 Byron Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and 50-455

Subject:

Annual 10 CFR 50.46 Report of Emergency Core Cooling System Evaluation Model Changes and Errors

Reference:

Letter from Patrick R. Simpson (Exelon Generation Company, LLC) to U.S.

NRC, "Annual 10 CFR 50.46 Report of Emergency Core Cooling System Evaluation Model Changes and Errors," dated April 7, 2016 In accordance with 10 CFR 50.46, "Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors," paragraph (a)(3)(ii), Exelon Generation Company, LLC, (EGC) is submitting the attached information to fulfill the annual reporting requirements for Braidwood and Byron Stations, Units 1 and 2. The attachments describe the changes in the evaluations associated with the accumulated peak cladding temperature (PCT) since the previous annual report submitted in the referenced letter.

There are no regulatory commitments contained in this submittal.

Should you have any questions concerning this letter, please contact Jessica Krejcie at (630) 657-2816.

Respectfully, i

David M, Gullott Manager Licensing

'Exelon Generation Company, LLC Attachments: 1) 3raidwood and Byron Stations, Units 1 and 2 10 CFR 50.46 Report

2) 3raidwood and Byron Stations, Units 1 and 2 10 CFR 50.46 Report Assessment Notes

April 7, 2017 U.S. Nuclear Regulatory Commission Page 2 cc: NRC Regional Administrator, Region I'0I NRC Senior Resident Inspector, :3raidwood Station NRC Senior Resident Inspector, Byron Station NRR Project Manager, Braidwood and Byron Stations l"nois Emergency Management Agency Division of Nuclear Safety

Attachment 1 Braidwood and Byron Stations, Units 1 and 2 10 CS=R 50.46 Report PLANT NAME- Braidwood Station Unit 1 ECCS EVALUATION MODEL: Small Break Loss of Coolant Accident (SBLOCA)

REPORT REVISION DATE: 4/7/17 CURRENT OPERATING CYCLE- 20 Evaluation Model: NOTRUMP Calculation- Westinghouse CSI-LIS-00-208, December 2000 Fuel- VANTAGE+ 17 x 17 Limiting Fuel Type- VANTAGE+ 17 x 17 Limiting Single Failure: Loss of one train of ECCS flow Limiting Break Size and Location- 2-inch Break in the Bottom of the Cold Leg Reference Peak Cladding Temperature (PCT) PCT = 1624.0°=

A. PRIOR LOSS OF COOLANT ACCIDENT (LOCH) V41ODEL ASSESSMENTS 10 CFR 50.46 report dated O'une 11, 2001 (Note 1) APCT = 0 OF 10 CFR 50.46 report dated April 18, 2002 (Note 2) PCT = C °=

10 CFR 50.46 report dated April 14, 2003 (dote 3) \PCT = 0 OF A. CFR 50.46 report dated A'oril 14, 2004 (Vote 4)

APCT = +35 ,:,F 10 CFR 50.48 report dated April 14, 2005 (Note 5) ADC- = 0 OF 10 CFR 50.46 report dated April 14, 2006 (Vote 6) AL j = r °r 10 CFR 50.46 report dated April 13, 2007 (Note 7) I APCT = 0 OF 30-Day 10 CFR 50.46 report dated June 22, 2007 ('Vote 9) A,:)CT = r~ °F 30-Day 10 CI- R 50.46 report dated November ', 9, 2037 (dote 10) PCT = +90 OF 10 CFR 50.46 report dated Aoril 11, 2008 (Note 11) APCT = 0 OF_

10 CFR 50.x.6 report dated April 9, 2009 (Note 12) APCT = 0 OF 10 CS=R 50.46 :-eoo,t dated Aoril 8, 2010 ;Note 13) PCT = 0 OF 10 CFR 50.46 report dated April 6, 2011 (Note 15) ,,PCT = 0 °F 10 CFR 50.4 .6 report dated A9r1*1 6, 2012 ,Note 17)  :\DCT _ 0 °r 10 C`R 50.46 report dated April 5, 2013 (No-We 19) APCT = C OF 10 CFR 50.46 reoort dated Ax] 7, 2014 Ncte 2") PCT = 0 °F 10 CF R 10.46 report dated Apr 17, 2015 (No":e 22) PCT = u 10 CFR 50.46 report dated Aoril 7, 2013 (dote 23) ,, PCT = C OF A

NET PCT PCT = 1749.0°F Page 1 of 12

Attachment 1 Braidwood and Byron Stations, Units 1 and 2 10 CFR 50.46 Report B. CURRENT LOCA MODEL ASSESSMENTS None (Note 24) APCT = 0 °F i

Total PCT change from current assessments APCT = 0 OF Cumulative PCT change from current assessments  ;;1PCT ; = 0 'F NET PCT PCT = 1749.0'F Page 2 of 12

Attachment 1 3raidwood and Syron Stations, Units 1 and 2 f' O 07R 50.46 Report PLANT NAME: Braidwood Station Unit 1 ECCS EVALUATION MODEL: Large Break Loss of Coolant Accident (LBLOCA)

REPORT REVISION DATE: 4/7/17 CURRENT OPERATING CYCLE- 20

COI Evaluation Model

ASTRUM (2004)

Calculation- Westinghouse WCAP-16841-P, November 2007 Fuel: VANTAGE+ 17 x 17 Limiting Fuel Type: VANTAGE+ 17 x 17 Limiting Single Failure: Loss of one train of ECCS flow Limiting 3reak Size and Location: Guillotine break in the Cold Leg Reference PCT PCT = 1913.0°F

"]ARGIN .ALLOCATION A. PRIOR LOCA MCDEL ASSESSMENTS 30-Day 10 CFR 50.46 report dated March 15, 2011 (Note 14) ,-PCT = 0 OF 10 CFR 50.46 report dated April 6, 2011 (Note 15) zNPCT = 0 OF 10 CFR 50.46 reoort dated Aoril 6, 2012 (Note 17)  ;PCT = 0 '-

30-Day 10 CFR 50.46 report dated May 21, 2012 (dote 18) APCT = +44 O F 10 CFR 50.46 resort dated April 5, 2013 (Note 19) AOCT = 0 °F 30-Day 10 CFR 50.46 report dated February 27, 2014 (Dote 20) ,NPCT = +66 OF 10 CFR 50.46 reoort dated April 7, 2014 (Note 21) APCT = 0 °F 10 CFR 50.46 report dated April 7, 2015 (Note 22)  ! ,1DCT = +? of 10 CFR 50.46 report dated April 7, 2016 (Note 23) /ND C-7 = 00=

NET PCT =C z' -- w"25.0°F B. CURRENT L ACA MODEL ASS _3S2,.6E~AIT3 General Code N aintenarce ('dote 24) sOCT = 0 Error in Ox.dat on CalcuiG 'ons (Note 24)  ?CT = O°7 Error in Use of ASVE Tables (Note 24) 1 A?CT = 0 "F To'ral PCT ci`iance fro: current assessments L .\PCT = 0 Cumulative ?CT cl :anae 4rom current assessrnen's PC-IT = 0 °F NET PCT PCT = 2025.0°F 71age 3 of 12

Attachment 1 Braidwood and Byron Stations, Units 1 and 2 10 CFR 50.46 Report PLANT NAME: Braidwood Station Unit 2 ECCS EVALUATION MODEL: Small Break Loss of Coolant Accident (SBLOCA)

REPORT REVISION DATE: 4/7/17 CURRENT OPERATING CYCLE 19 Im

`valuation Model. NOTRUMP Calculation: Westinghouse CN-LIS-00-208, December 2000

=uel: VANTAGE+ 17 x 17 Limiting Fuel Type: VANTAGE+ 17 x 17 Limiting Singe Failure: Loss of one train of ECCS flow Limiting Break Size and Location: 2-inch Break in the Bottom of the Cold Leg Reference PCT PCT = 1627.0°F MARGIN ALLOCATION 10 CFR 50.46 report dated June 11, 2001 (Note 1)  ?CT = +3 °F 10 CFR 50.46 report dated April 18, 2002 (Note 2) ,APCT = 0 ° 10 CFR 50.46 report dated April 14, 2003 (Note 3) ,PCT = 0 °F 10 CFR 50.46 report dated Apr] 14, 2004 (Note 4.) :PCT = +35 F 10 CFR 50.46 report dated April 14, 2005 (Note 5)  ; .PCT = 0 °F 10 C1=13 50.46 report dated April 14, 2006 (Note 6)  ?CT = 0 °F 10 CFR 50.46 report dated April 13, 2007 (Note 7) A?CT = 0 °F 30-Day 10 CFR 50.46 report dated June 22, 2007 ('X'ote 9) A?CT = 0 °F 10 CF; 50.46 report dated April 11, 2008 (Note 1 1) PCT = +3 t 10 CFR 50.46 report dated April 9, 2009 (Note 12) A'DCT = 0 DF 10 CFR 50.46 reoort dated Aorii 8, 2010 (Note 13) 1 A?CT =0 °F 10 CFR 50.46 report dated April 6, 2011 (Note '15) -PCT = 0 °r 10 CFR 50.46 report dated April 6, 2012 (Note 17) APCT = 0 'D 10 CFR 50.46 reoort dated Aorii 5, 2013 (Note 19) . PCT = 0 °F 10 CFR 50.46 report dated Ax] 7, 2014 (Note 21) s'DCT = 0 O F 10 CFR 50.46 report dated Apra 7, 2015 (Note 22) :N?CT = 0 O F 10 CFR 50.46 report ca.ted Aor l 7, 2018 (No,-,a 23)  ?CT = 0 °F NET PCT PCT = 1755.0'F mace 4 c-i ' 2

a':tachment 1 3raidwood and Syron Stations, Units 1 and 2

'0 CR 50.46 'Report B. CURRENT LOCO MOD EL ASSESSMENTS None (Note 24)  ! ,\PCT = 0 OF Total PCT change from current assessments X "\PCT = 0'-- F Cumulative PCT change from current assessments , N, APCT = 0 "!_

NET PCT PCT = ' 755.0°F

~q e c-0:ate 2

Attachment 1 3raidwood and Byron Stations, Units 1 and 2 10 CFR 50.46 Report PLANT NAME: Braidwood Station Unit 2 ECCS EVALUATION MODEL: Large Break Loss of Coolant Accident (LBLOCA)

REPORT REVISION DATE: 4/7/17 CURRENT OPERATING CYCLE: 19 1-kOR Evaluation Model: ASTRUUI (2004)

Calculation: Westinghouse WCAP-16841-P, November 2007 Fuel- VANTAGE+ 17 x 17 Limiting Fuel Type: VANTAGE+ 17 x 17 Limiting Single Failure: Loss of one train of ECCS flow Limiting Break Size and Location: Guillotine break in the Cold Leg Reference PCT PCT = 2041.0°F 1ARG:N ALLOCATION

,-k. PRIOR LOCH MODEL ASSESSMENTS 30-Day 10 CFR 50.46 report dated March 15, 2011 (Note 14) APCT = 0 °F 10 CFR 50.46 report dated April 6, 2011 (Note 15) APCT = 0 "F 30-Day 10 CFR 50.46 report dated March 19, 2012 (Note 16) APCT = -42 °F 10 CFR 50.46 reoorf dated Aorl 6, 2012 (Note 17) APCT = 0 °F 10 CFR 50.46 report dated Aoril 5, 2013 (Note 19) APCT = 0"F ,

10 CFR 50.46 reoort dated April 7, 2014 (Note 21) ,:PCT = +46

^.0 CFR 50.46 report dated April 7, 2015 (Note 22) APCT = +2 "F 0 CFR 50.46 report dated April 7, 2016 (Note 23) APCT = 0 OF NET PCT PCT = 2047.0°F B. CURRENT LCCA MODEL ASSESSMENTS General Code Maintenance (Vote 24) .\PCT = 0 `F Error in Ox catson Calcu at ons (Note 24) APCT = 0')F Error in Use of ASME Tab!es (Note 24) ALOCT = 0 °F Evaluations of ;Tae "fects of Containment Purge on the Containment _\,= CT = 0')F Pressure Res onse Note 24 Total PCT change from current assessments s APC`~ = 0 OF Cu;rulat`,ve PCT change -':rom current assessments V PCT = 0 OF NET PCT PCT = 2047.0°F

?age 6 04 12

Attachment 1 Braidwood and Byron Stations, Units 1 and 2 10 CFR 50.46 Report PLANT NAME: Byron Station Unit 1 ECCS EVALUATION MODEL: Small Break Loss of Coolant Accident (SBLOCA)

REPORT REVISION DATE: 4/7/17 CURRENT OPERATING CYCLE: 22 ANALYSIS OF RECORD (AOR)

Evaluation Model: NOTRUMP Calculation: Westinghouse CN-LIS-00-208, December 2000

=uel: VANTAGE+ 17 x 17 Limiting Fuel Type: VANTAGE+ 17 x 17 Limiting Single Failure: Loss of one train of ECCS flow Limiting Break Size and Location: 2-inch Break in the Bottom of the CoEd Leg Reference Peak Cladding Temperature (PCT) PCT = 1624.0°F 11ARGIN ALLOCATION A. PRIOR LOSS OF COOLANT ACCIDENT (LOCA) MODEL ASSESSMENTS 10 CFR 50.46 report dated une 11, 2001 (Note 1) \PCT = 0 °F 10 CFR 50.46 reoort dated Aoril 18, 2002 (Note 2) APCT = 0 OF 10 CFR 50.46 report dated April 14, 2003 (Note 3)  :\PCT = 0 OF 10 CFR 50.46 report dated Aoril 14, 2004 (Note 4) JPCT = +35 OF 10 CFR 50.46 report dated April 14, 2005 (Note 5) APCT = 0 O F-10 CFR 50.46 reoort dated Ann] 14, 2006 (Notre 6) JPCT = 0 °-

10 CFR 50.46 report dated April 13, 2007 (Note 7) A?CT = 0 °F 30-Day 10 CFR 50.46 report dated June 22, 2007 (dote 9) A?CT = 0 O F 10 CFR 50.46 report crated Aoril 11 2008 (Note 11) -\PCT = +,,-,, 0 'F 10 CFR 50.46 report dated Aoril 9, 2009 (Note 12) :PCT = 0 °F 10 CFR 50.46 reoort dated April 8, 2010 (Note 13) APCT = 0 OF 10 CFR 50.46 reoort dated Aoril 6, 2011 (Note 15) JPCT = 0 OF 10 CFR 50.46 report dated April 6, 2012 (Note 17) :PCT := 0 OF 10 CFR 50.46 report dated Apr] 5, 2013 (Note 19) , PCT = 3 IF 10 CFR 50.46 report dated Aoril 7, 2014 (Note 21) -\?CT = 0 OF 10 CFR 50.46 reoort dated April 7, 2015 (Note 22) D =D° 10 CFR 50.46 reoort dated April 7, 2016 (Note 23) ~?CT

' = 3 0'-

NET PCT PCT = 1749.0°F

,ace 7 cI 1?

A'tachment 1 Braidwood and Byron Stations, Units 1 and 2 10 CFR 50.46 Report B. CURRENT LOCO MODEL ASSESSMENTS None (Note 24) .\PCT = 0 -F Total PCT change from current assessments APCT = 0 -IF Cumulative PCT change from current assessments APCT = 0 I)F

,~IET PCT PCT = 1749.0°F

'age 8 of 12

Attachment 1 3raidwood and Byron Stations, Units 1 and 2

.0 CFR 50.46 Deport PLANT NAME: Byron Station Unit 1 ECCS EVALUATION MODEL: Large Break Loss of Coolant Accident (LBLOCA)

REPORT REVISION DATE: 4/7/17 CURRENT OPERATING CYCLE: 22

,FOR Evaluation Model: ASTRUM (2004)

Calculation: Westinghouse WCAP-16841-P, November 2007

'=uel: VANTAGE+ 17 x 17 Limiting Fuel Type: VANTAGE+ 17 x 17 Limiting Single Failure: Loss of one train of ECCS flow Limiting Break Size and Location: Guillotine break in the Cold Leg Reference PCT PCT = 1913.07 YIARG~N ALLOCATION A. PRIOR LOCA .MODEL ASSESSMENTS 30-Day 10 CFR 50.46 report dated March 15, 2011 (Note 14) APCT = 0 OF 10 CFR 50.46 report dated Aoril 6, 2011 (Note 15) APCT = 0 OF 10 CFR 50.46 report dated April 6, 2012 (Note 17) APCT = 007 30-Day 10 CF's 50.46 report dated May 21, 2012 (Note 18) APCT = +44 O F 10 CFR 50.46 report dated April 5, 2013 (Note 19) APCT = 0 OF 30-Day 10 CFR 50.46 report dated February 27, 2014 (Note 20) NPCT = +66 OF 1 10 CFR 50.4.6 report dated Ar)r'I 7, 2014 (Note 21) APCT = 0 OF 10 CFR 50.46 report Gated April 7, 2015 (Note 22) \PCT = +2 °F 10 CFR 50.46 report dated April 7, 2016 (Note 23) APCT = 0 NET PCT PCT = 2025.0°F B. CURRENT LOCA MODEL ASS =SSMENTS General Code Mainterance (Note 24) _VOCT = 0 OF Er-or in Ox'dat°on Calcu ations (Note 24) A?CT = 0 °F Error it Use of ASME Tables (Note 24) APCT = 0 °F Total RCT c^ange from current assessments L ,\PC_ = 0 O Cumulat've PCT c ange from current assessments -C A-NET PCT PCT = 2025.0'F dace 9 cu 12

Attachment 1 Sraidwood and Byron Stations, Units 1 and 2 10 CFR 50.46 Report PLANT NAME: Byron Station Unit 2 ECCS EVALUATION MODEL: Small Break Loss of Coolant Accident (SBLOCA)

REPORT REVISION DATE: 417117 CURRENT OPERATING CYCLE: 20 AOR Evaluation Model: NOTRUMP Calculation: Westinghouse CN-LIS-00-208, December 2000 Fuel: VANTAGE+ 17 x 17 Limiting Fuel Type: VANTAGE+ 17 x 17

"-imiting Single Failure: Loss of one train of ECCS flow Limiting Break Size and Location: 2-inch Break in the Bottom of the Cold Leg Reference PCT PCT = 1627.0°F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS 10 CFR 50.46 report dated June 11, 2001 (Note 1) APCT = +3 "F 10 CFR 50.46 report dated April 18, 2002 (Note 2) ARCT = 0 OF 10 CFR 50.46 report dated April 14, 2003 (Note 3) APCT = 0 °F 10 CFR 50.46 reoort dated April 14, 2004 (Note 4) APCT = +35 `F 10 CFR 50.46 report dated April 14, 2005 (Note 5) , PCT = 0 O F 10 CFR 50.x6 reoort dated April 14, 2006 (Note 6) JRCT = 0 °F 10 CFR 50.46 report dated April 13, 2007 (Note 7) APCT = C °F 30-Day 10 C=R 50.46 report dated "day 10, 2C07 (Note 8) APCT = +90 OF 30-Day 10 CFR 50.46 report dated June 22. 2007 (Note 9) \?CT = 0 °F 10 CFR 50.46 report dated April 11, 2008 (Note 11) APCT = 0 OF 10 CFR 50.46 report dated April 9, 2009 (Note 12) APCT = 0 OF 10 CFR 50.46 report dated Aorl 8, 2010 (Note 13) .PCT = 0 OF 10 CFR 50.46 report dated Aorii 6, 2011 (Note 15) ARCT = 0 °F 10 CFR 50.46 reoort dated A°)ril 6, 2012 (Note 17) PCT = C OF 10 CFR 50.46 report dated Apr°J 5, 2013 (Note 19) APCT = 0 OF 10 CFR 50.46 report dated Aoril 7, 2014 'Note 21) APCT = C OF 10 CFR 50.46 report dated Aorl 7, 2,315 (Note 22) ARCT = 0 10 CFR 50.46 report dated Aoril 7, 2016 (Note 23) .~?CT = C °F

=T -=, CT PCT = 1755.0°F Page 10 of 12

Attachment 1 Braidwood and Byron Stations, Units 1 and 2 10 CFR 50.46 Report B. CURRENT LOCA MODEL ASSESSMENTS None (Note 24) JPCT = 0 OF Total PCT change from current assessments }I : PCT = 0 `F Cumulative PCT change from current assessments ~; \PCT . = 0 °F NET PCT PCT = 1755.0° F Page 11 of 12

Attachment 1 3raidwood and Byron Stations, Units 1 and 2 10 CFR 50.46 Report PLANT NAME: Byron Station Unit 2 ECCS EVALUATION MODEL: Large Break Loss of Coolant Accident (LBLOCA)

REPORT REVISION DATE: 4/7/17 CURRENT OPERATING CYCLE: 20 AO'R Evaluation Model: ASTRUM (2004)

Calculation: Westinghouse WCAP-16841-P, November 2007 Fuel: VANTAGE+ 17 x 17 Limiting Fuel Type: VANTAGE+ 17 x 17 Limiting Single Failure: Loss of one train of ECCS flow Limiting Break Size and Location: Guillotine break in the Cold Leg Reference PCT PCT = 2041.0°F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS 30-Day 10 C47R 50.46 report dated //larch 15, 2011 (Note 14) PCT = 0'--F 10 CFR 50.46 report dated April 6, 20.11 (Note 15) A?CT = 0 r'F 30-Day 10 CFR 50.46 report dated March 19, 2012 (Note 16) A?CT = -42 °-

10 CFR 50.46 report dated April 6, 2012 (Note 17) APCT = 0 °F 10 CFR 50.46 report dated April 5, 2013 (Note 19) <A?CT = 0 °F 10 CFR 50.46 report dated April 7, 2014 (Note 21) A DCT = +46 OF 10 CFR 50.46 report dated April 7, 2015 (Note 22) APCT = +2 °F 10 CFR 50.46 re!iort dated Aor.l 7, 2016 (Note 23) A?CT = 0 OF NET PCT ':--

c.T = ,1.047.C'.

B. CURRENT LOCA MODEL ASSESS: 'iEK,TS General Code Maintenance (.:vote 24) ,PCT = 0 F Error in Oxic a °on Calcu,at ons (Note 24) APCT = 0 °F Error in Use of ASME Tables (vote 24) APCT = 0 °=

Evaluations of ~t:^e Effects of Containment' urge on -'he Containment ,PCT = ,%30 °F Pressure Response Note 24)

Tonal PCT chance from current assessments .\PC- = 0 OF Cumulative PC7 el^ange from current assessr-er s i APCT = 0 `F NET PCT PCT = 2047.0'F

`0 :1ge 20 "2

Attachment 2 Braidwood and Byron Stations, Units 1 and 2 10 CFR 50.46 Report Assessment Notes

1. Prior Loss of Coolant Accident (LOCA) Model Assessment The 10 CFR 50.46 report dated June 11, 2001 reported new Small Break Loss of Coolant Accident (SBLOCA) analyses to support operations at uprated power conditions. The same report assessed the impact from annular axial blankets on SBLOCA analysis, which determined a 0°F Peak Clad Temperature (PCT) penalty for Units 1 and a 3°F PCT penalty for Units 2. Evaluations for plant conditions and SBLOCA model changes which resulted in 0°F PCT change were reported.

2. Prior LOCA Model Assessment The 10 CFR 50.46 report dated April 18, 2002 reported evaluations for SBLOCA model changes which resulted in 0°F PCT change.

3. Prior LOCA Model Assessment The 10 CFR 50.46 report dated April 14, 2003 reported evaluations for SBLOCA model changes which resulted in 0°F PCT change.

4. Prior LOCA Model Assessment The 10 CFR 50.46 report dated April 14, 2004 reported evaluations for a SBLOCA assessment related to NOTRUMP bubble rise/drift flux model inconsistency corrections, which resulted in 35°F PCT assessment.

5. Prior LOCA Model Assessment The 10 CFR 50.46 report dated April 14, 2005 reported evaluations for SBLOCA model changes which resulted in 0°F PCT change for Byron and Braidwood Stations, Units 1 and Unit 2. The Braidwood Station Unit 1 assembly N10S was reconstituted with two stainless steel filler rods during Braidwood Station Unit 1 Refueling Outage 11. This assembly is reloaded into the core and is in use during Braidwood Station Unit 1 Cycle 12 operation.

The introduction of up to five stainless steel filler rods has been evaluated and shown to have no impact on SBLOCA analysis. The estimated PCT effect is 0°F for Braidwood Station Unit 1. This assembly was discharged during Reload 12.

6. Prior LOCA Model Assessment The 10 CFR 50.46 report dated April 14, 2006 reported evaluations for SBLOCA NOTRUMP General Code Maintenance which resulted in 0°F change.

7. Prior LOCA Model Assessment The 10 CFR 50.46 report dated April 13, 2007 reported evaluations for SBLOCA model changes and errors. The report documented general code maintenance for NOTRUMP, AXIOM lead test assembly evaluation and NOTRUMP refined break spectrum, which resulted in 0°F PCT impact.

Page 1 of 6

Attachment 2 Braidwood and Byron Stations, Units 1 and 2 10 CFR 50.46 Report Assessment dotes

8. Prior LOCA Model Assessment The 30-day 10 CFR 50.46 report dated May 10, 2007 applicable to Byron Station Unit 2 reported an assessment of the Emergency Core Cooling System (ECCS), which evaluated changes in ECCS `low during the recirculation phase due to Generic Safety Issue (GSI) -

191 related safety injection (SI) throttle valve replacements. The evaluation of recirculation phase ECCS flow changes relative to impact on the current Analysis of Record (AOR) was performed for the SBLOCA. Based on the NOTRUMP and SBLOCTA calculations performed for Byron Station Unit 2, a conservative, bounding PCT assessment of +90°F was applied to the current Byron Station Unit 2 SBLOCA PCT.

9. Prior LOCA Model Assessment Tine 30-day 10 CFR 50.46 report dated June 22, 2007 applicable to Byron Station Units 1 and 2 and Braidwood Station Units 1 and 2 reported an error in the HOT SPOT Code which did not impact the SBLOCA analysis. The 30-day report also reported minor errors with the reactor vessel data collections that potentially affected the vessel inlet and outlet fluid volume, metal mass and surface area. The corrected values were evaluated for impact, and a 0°F penalty was assessed for Byron Station Urits 1 and 2 and Braidwood Station Units 1 and 2, SBLOCA analysis.

10. P,°or LOCA IViodel Assessment T;-~e 30-day 10 CFR 50.46 report dated November 19, 2007 applicable to Braidwood Station unit 1 reported an assessment of the Emergency Core Coolirg System (ECCS), which evaluated changes in ECCS '!ow during the recirculation phase cue to GSI-191 related SI rdtle valve replacements. Tine evaluation of recirculation phase `CCS flow changes relative to impact on the current Analysis of record (AOR) was ;performed for tine SBLOCA.

Based on the 1VOTRUMP and SBLOCA calculations performed for z3r&dwood S~ation Unit 1, a conservative, bounding PCT assessment of +90'F was applied to the Braidwood Station Unit 1 SBLOCA PCT.

1". ?rior LOCA CV'odel Assessment TI,e 10 CFR 50.46 report dated Apr] 11, 2008 reported evaluations for LOCA model chances and errors. Applicable to Braidwood Statior Unit 2 and Byron Station Unit 1, `;-e ECCS assessment evaluated dianges n ECCS f:ow during the recirculaticn phase due to GS,'-191 related safety 'njection S1 tinrcttle vaive replacements. A conservative, bounding

?CT assessment o -90°F was applied to the 3raidwood Station Unit 2 and Byron Station Unit 1 SBLOCA PCT s. The repot a='so docLmented general code mairtenarce for SBLOCA and evaluation for puMp weir resistance modeling 'or SBLCCA analyses, which resulted in 0°F PCT 1moact.

12. Prior LOCA :Model Assessment The 10 Ci=R 53.46 report dated April 9, 2G09 reported evaluations for LOCA mcdel changes and errors. Tine report documents generai code mairt-enance for SBLOCA, errors in reactor vessel lo,.ver plenum surface area calculations, discrepancies in metai mass - rom drawings,

?age 2 of 3

Attachment 2 3raidwood and (Byron Stations, Units 1 and 2 10 CFR 50.46 Report Assessment Notes and an evaluation of Areva Lead Use Assemblies. All of which have a 0°F PCT penalty associated with them.

13. Prior LOCA Model Assessment The 10 CFR 50.46 report dated April 8, 2010 reported no evaluations for SBLOCA model changes which resulted in 0°F PCT change.

14. Prior LOCA "Model Assessment The 30-day 10 CFR 50.46 report dated March 15, 2011 reported a new large break BELOCA (ASTRUM ) analysis to support operations for Byron and Braidwood Stations, Units 1 and 2. The same report assessed the impact from several errors, issues, and code enhancements. Each of these errors/issues/code enhancements had a 0°F PCT impact with a net 0°F PCT impact.

15. Prior LOCA Model Assessment T,ne 10 CFR 50.46 report dated April 6 , 2011 reported no evaluations for the Large Break LOCA model. For the SBLOCA model, the following errors, changes, corrections or enhancements were reported. Two errors relating to urania-gadolinia pellet thermal conductivity calculation, two errors relating to pellet crack and dish volume calculation, a discrepancy involving the treatment of vessel average temperature uncertainty , and genera' code maintenance were reported for the SBLOCA model. All of these ,ssues were determined to have an estimated impact of 0°F.

13. Prior LOCA iV'odel Assessment

_r 11 30-day 10 CFR 50.46 report dated ;March 19, 2012 applicable to Bra:dwood Station snit L and Byron Station Unit 2 reported an assessment of Thermal Conductivity Decradation (-CD) with an associated peaking factor burndown and a design input change consisting of a reduction in upper bound steam generator tube plu g ging , a reduction in nominal upper bound nominal vessel average temperature, and an increase in the assumed containment pressure boundant condition. As a result, the estimated effect of tl e TCD with burndown was determined to be +148° F and t^e estimated effect of the design input changes was Determined to be -190° F. These two assessments ar,e coupled together via their eva , uat~ons of burnup effects which i nclude thermal conductivity degradation , peaking factor burrdown and design i nput changes. T herefore, the combined affect of til~ese two charges results in a net c,-~ange in the reported LHOCA PCT for Lra dwood Station Unit 2 and Byron Station Unit 2 of -42°F.

17. Prior LOCA Voc,el Assessment The 10 CFR 50.46 report dated April 5, 2012 reported eva rations for LCCA _Mcdel changes and errors. The report documents ger~erai cope maintenarce for both SBLOCA and BL CCA, srrors in Radiation Heat sfer Logic for SB:_OCA, and an error in the Maximum

=_,el Rod 7me Step Logic V- SBLOCA. A: of which have a °F PCT penalty associated them.

Rage 3 of 6

Attachment 2 Braidwood and Byron Stations, Units 1 and 2 10 CFR 50.46 Report Assessment Notes

18. Prior LOCA Model Assessment The 30-day 10 CFR 50.46 report dated May 21, 2012 applicable to Braidwood Station Unit 1 and Byron Station Unit 1 reported an assessment of TCD with an associated peaking factor burndown an analysis input change consisting of a reduction in conservatism in analyzed FQ values and an increase in the assumed containment pressure boundary condition. As a result, the estimated effect of the TCD with burndown was determined to be +110°F and the estimated effect of the analysis input changes was determined to be -66°F. These "Lwo assessments are coupled together via their evaluations of burnup effects which include thermal conductivity degradation , peaking factor burndown and analysis input changes.

Therefore, the combined affect of these two changes results in a net change in the repor- ed LBLOCA PCT for Braidwood Station Unit 1 and Byron Station Unit 1 of +44°F.

19. Prior LOCA Model Assessment The 10 CFR 50.46 report dated April 5, 2013 reported evaluations for LBLOCA model changes, and HOTSPOT and WCOBRA/TRAC code corrections. For SBLOCA, TCD was evaluated with NOTRUMP to estimate the effect on the limiting cladding temperature model.

All evaluations led to PCT impact of 0°F.

20. Prior LOCA Model Assessment The 30-day 10 CFR 50.46 report dated February 27, 2014 applicable to 3raidwood Station Unit 1 and Byron Station Unit 1 reported evaluations for LBLOCA model changes and code correctlors. For 3raidwood Station Iv njt 2 and Byron Station Unit 2 a ret change of 46°F PCT **pact did not require inclusion in the 30-day report and is reported 1^herein . Revised i-eat transfer rnultipEer distributions, charges to grid blockage ratio and porosity and I IOTSPOT burst strain error corrections was Cletermi:ned to be 5°F, 240 =, and 37°F PCT mpact, respectively for Braidwood Station Un.t 1 and Syron Station t. rit 1. Other model changes and code correct oins sum to O°F PCT impact. Therefore, tine combined effect of tine changes resulted in a ret dhange of 66°F PCT impact for Braidwood Station Unit 1 and Syron Station Unit I.

21. Prior LOCA Model Assessment Fle 10 CFR 50.x-6 report dated Apr'] 7, 2014 applicable to 3raidwood Station ,:nit 2 and Syron Station Lnit 2 reported evaluatlons for LBLOCA ,yodel c urges and code correc':` ons.

For Braidwood Station Unit 1 and Syron Station Unit 1 a net change cf 66°F PCT imoact required a 30-day report sent on =ebruary 27, 2014 ( Note 20). Revised heat transfer multiplier dis:rli~:~tions, cinar ,es to grid blocl<age ratio and porosity and HOTS6 1 bu st strain error corrections was deterrn ' ned to be 7°F, 247, and 15°F PCT impact, .-esoect,*ve'y for Braidwood S'.aton Unit 2 and Syron Station 2. Other model cnanges and code corrections sum to O'F PCT impact. Therefore, the combined effect of the cinanges resulted in a ret cn,ange of 46°F PCT impact for Braidwood Station Unit 2 and Byron Station Unit 2 LE'-OCA. S3-OCTA cladding strain requirement for fuel rod burst resulted in a 07 PCT impact to Syron and Braidwood Stations, Units 1 and 2 SBLOCA.

'ace 4 of 6

Attachment 2 Braidwmodand Bvrmn3tatimna, Units and

`OCFR 50.46,Report ssessmentNotes

22. Prior LOCA Model Assessment The 10 CFR 50.46 report dated April 7, 2015 reported General Code Maintenance and a change to Safety Injection endCoreSproyflovvrateoforLBL[)CA&SBL{]CA. The report also reported an error in the decay group uncertainty factor for LKOCA, errors in the fuel rod gap conductance, radiation heat transfer model and pre-DNB cladding surface heat

~ransfer coefficient and an evaluation to [ncreased Auxiliary feedwater switchover delayfor SBLOCA. VVith the exception of2"F PCT impact toLBLDCA due to the change toSafety

ryectionondCone8prayflovvs.allotherohangeanaportodaninnpaotofO"FPCT.

23. Prior LOCA Model Assessment The 10 CFR 50.46 report dated April 7, 2016 reported General Code Maintenance for the SBLOCA which led to a PCT impact of OOF There were no impacts to LBLOCA.

24.Current LOCA Model Assessment For the current LBLOCA analysis, mahouaohengoshavebeannnodetoenhencethe coaY]tvof codes and toetreann line future analyses. Examples of these changes include nnod~ving inputv~riab~e de~nitions. uni~a ~nd defeults~ *~rnproving the input diagnostic checks; enhancing the code Output' optimizing active coding; and eliminating inactive ood.ng. T:-,eoe changes resulted inon estimated PCT impact ofO"F.

There were two errors assessed to the ' BU]CAenelysis. T~~e first error was ne(e~d '.o the ms(ou~stlon of:~,~chtenrperadune oxidation within a rea]et/c ~'orQe break L(]CA oofoulc

-tion. l-i was determined that correcting the high temperature oxidation calculation ~n VVC[)BF{A/TRAC)o estimated to:iraveanog(igib~e impact ontne BELBLOCA PCT ono;yaiareeul~a.(eadingtoan estimated PCT impact ofO7 for 1OCFIR 5Q46 reporting purposes. The second error was related to tire use oft'~~,e American Society of)jleohenioe(H-- ngMeere(A8&CE) steam tables to calculate tile steady-state Lipper heed l,~quid temperature aaofunotionofthe pressure and spec~fioentha)pyin -the A8TF<UM so~vvare program. The steam ta'ole epp{icob[eto steam/gas is used to deternn}netho upper

-ead u'dternoerature. Hovvever. the vvoter[n the upper head is/nthesub000(edl~quid o~e1eduftg normal operation (ard the steady-state oalcm(ation). 7-erefore. the steam table 2ppl,.'cab',e to liquid should be used to determine the upperlead fluid temperature. )~vvaa (feternnined that the tann- Deraturea calouleted by the AS0E steam tab'eo epp,,cableto tl~e s~e2rn/ges side ard the liquid side are very similar within tile typical upper head pressure and ~)qu"d specific entha/py ranges. Therefone, this error was eveivated to lave o negligible j=, act on the BE'.-OCA anaiysis results, leadirg to an estimated PC7, impact o-f 07 `or 10

(~FF~5Q.48reoort'rgpurposes.

ere was one evaluat-~n to tile LBLOCA anallysis on t..ie effect of con' ainment purge ontNa containment nreaounereajomae. TheByronG~ation~n~2 and E- reidvvoodG~ation Unit 2 analysis modeled the ef7ect-aofnuq]~nq using apotent!s))ynon-corservs~ivemethod. An evo(uation has been cornp.~etedtoee"Zinnotethee-!:~,:eotofcontainrnent ocrgeonthe oonta(nnnent response us,ngo More eppropr}ate/oonsen'et(ve method and was es1>rne-ed~o have a negligible impact on t1le containment backpreSSUre response, 'eading to an eoUmated PCT impact ofO"F Page 5 cf SO

Attachment 2 Braidwood and Byron Stations, Units 1 and 2 10 CFR 50.46 Report Assessment Notes Therefore, there is no PCT impact to the LBLOCA analysis from the evaluations and assessments within this report. Furthermore, the SBLOCA analysis was not impacted by any assessment within this report.

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