ML18121A449

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Cycle 20 Core Operating Limits Report
ML18121A449
Person / Time
Site: South Texas STP Nuclear Operating Company icon.png
Issue date: 04/30/2018
From: Dunn R
South Texas
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
NOC-AE-18003563
Download: ML18121A449 (19)
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Text

Nuclear Operating Company South Texas Project Electric Genei-atlng Station P.O. Box 289 Wadsworth, Texas 77483 April 30, 2018 NOC-AE-18003563 10CFR 50.36 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 South Texas Project Unit 2 Docket No. STN 50-499 Unit 2 Cycle 20 Core Operating Limits Report In accordance with Technical Specification 6.9.1.6.d, STP Nuclear Operating Company submits the attached Core Operating Limits Report (COLR) for Unit 2 Cycle 20. The report covers the core design changes made during the 2RE19 refueling outage.

There are no commitments in this letter.

If there are any questions regarding this report, please contact Wendy Brost at (361) 972-8516 or me at (361) 972-7743.

^-?^>c^.

Roland F. Dunn

Manager, Nuclear Fuel & Analysis web

Attachment:

South Texas Project Unit 2 Cycle 20 Core Operating Limits Report, Revision 0 STI:34653746

NOC-AE-18003563 Page 2 of 2 ec:

(paper copy)

Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 1600 East Lamar Boulevard Arlington, TX 76011-4511 Lisa M. Regner Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North (08H04) 11555 Rockville Pike Rockvitle, MD 20852 NRC Resident Inspector U. S. Nuclear Regulatory Commission P.O. Box 289, Mail Code: MN116 Wadsworth.TX 77483

NOC-AE-18003563 Attachment Attachment South Texas Project Unit 2 Cycle 20 Core Operating Limits Report, Revision 0

Nuclear Operating Company SOUTH TEXAS PROJECT Unit 2 Cycle 20 CORE OPERATING LIMITS REPORT Revision 0 Core Operating Limits Report Page 1 of 16

Unit 2 Cycle 20

^y^ng^ny Core Operatmg Limits Report Rev. 0 Page 2 of 16 1.0 CORE OPERATING LIMITS REPORT This Core Operatmg Limits Report for STPEGS Unit 2 Cycle 20 has been prepared in accordance with the requirements of Technical Specification 6.9.1.6. The core operating limits have been developed usm^

the NRC-approved methodologies specified in Technical Specification 6.9.1.6.

The Technical Specifications afifected by this report are:

SAFETY UMITS LIMITING SAFETY SYSTEM SETTINGS SHUTDOWN MARGIN MODERATOR TEMPERATURE COEFFICDENT LIMITS SHUTDOWN ROD INSERTION LIMITS CONTROL ROD INSERTION LIMITS AFD LIMITS HEAT FLUX HOT CHANNEL FACTOR NUCLEAR ENTHALPY RISE HOT CHANNEL FACTOR DNB PARAMETERS 2.0 OPERATING LIMITS The cycle-specific parameter limits for the specifications listed m Section 1.0 are presented below.

2.1 SAFETY LIMITS (Specification 2.1):

2.1.1 The combination of THERMAL POWER, pressurizer pressure, and the highest operating loop coolant temperatoe (Tavg) shall not exceed the limits shown in Figure 1.

2.2 LIMITING SAFETY SYSTEM SETTD^GS (Specification 2.2):

2.2.1 The Loop design flow for Reactor Coolant Flow-Low is 98,000 gpm.

1) 2)

3) 4)

5) 6)

7) 8)

9) 10) 2.1 2.2 3/4.1.1 3/4.1.1 3/4.1.3 3/4.1.3 3/4.2.1 3/4.2.2 3/4.2.3 3/4.2.5

.1

.3

.5

.6

Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 3 of 16 2.2.2 The Over-temperature AT and Over-power AT setpoint parameter values are listed below:

Over-temperature AT Setpoint Parameter Values TI measured reactor vessel AT lead/lag time constant, TI = 8 sec T2 measured reactor vessel AT lead/lag time constant, T2 = 3 sec T3 measured reactor vessel AT lag time constant, TS = 2 sec T4 measured reactor vessel average temperature lead/lag time constant, n = 28 sec T5 measured reactor vessel average temperah.ire lead/lag time constant, TS== 4 sec T6 measured reactor vessel average temperature lag time constant, T6 = 2 sec Ki Overtemperature AT reactor faip setpoint, Ki = 1.14 K.2 Overtemperature AT reactor trip setpoint Tavg coefficient, K2 = 0.028/°F K.3 Overtemperature AT reactor trip setpoint pressure coefficient, KB = 0.00143/psi T Nominal full power Tavg, T'< 592.0 °F P' Nominal RCS pressure, P'== 223 5 psig fi(AT) is a function of the indicated difference between top and bottom detectors of the power-range neutron ion chambers; with gains to be selected based on measured instrument response during plant startup tests such that:

(1) For qi - qb between -70% and +8%, fi(AT) = 0, where qi and qb are percent RATED THERMAL POWER in the top and bottom halves of the core respectively, and qi + qb is total THERMAL POWER in percent of RATED THERMAL POWER; (2) For each percent that qi - qb is more negative than -70%, the AT Trip Setpoint shall be automatically reduced by 0.0% of its value at RATED THERMAL POWER; and (3) For each percent that qi - qb is more positive than +8%, the AT Trip Setpoint shall be automatically reduced by 2.65% of its value at RATED THERMAL POWER.

(Reference 3.6 and Section 4.4.1.2 of Reference 3.7)

Over-power AT Setpoint Parameter Values TI measured reactor vessel AT lead/lag time constant, TI = 8 sec T2 measured reactor vessel AT lead/lag time constant, T2 = 3 sec T3 measured reactor vessel AT lag time constant, TS = 2 sec T6 measured reactor vessel average temperature lag time constant, T6== 2 sec T7 Time constant utilized in the rate-lag compensator for Tavg, T? = 10 sec K4 Overpower AT reactor trip setpoint, K4 = 1.08 Ks Overpower AT reactor trip setpoint Tavg rate/lag coefficient, Ks = 0.02/°F for increasing average temperature, and KS = 0 for decreasing average temperature K.6 Overpower AT reactor trip setpoint Tavg heatip coefficient K6 =0.002/OFforT>T",and K6 = OforT^ T" T" Indicated fall power Tavg, T"$ 592.0 °F f2(AT) = 0 for all (AT)

Unit 2 Cycle 20

^^op^ng^^ny ^^ Operating Limits Report Rev. 0 Page 4 of 16 2.3 SHUTDOWN MARGIN (Specification 3.1.1.1):

The SHUTDOWN MARGIN shall be:

2.3.1 Greater than 1.3% Ap for MODES 1 and 2*

  • See Special Test Exception 3.10.1 2.3.2 Greater than the limits in Figure 2 for MODES 3 and 4.

2.3.3 Greater than the limits m Figure 3 for MODE 5.

2.4 MODERATOR TEMPERATURE COEFFICDENT (Specification 3.1.1.3):

2.4.1 The BOL, ARO, MTC shall be less positive than the limits shown in Figure 4.

2.4.2 The EOL, ARO, HFP, MTC shall be less negative than -62.6 pcm/°F.

2.4.3 The 300 ppm, ARO, HFP, MTC shall be less negative than -53.6 pcm/°F (300 ppm Swveillaace Limit).

Where: BOL stands for Begiiming-of-Cycle Life, EOL stands for End-of-Cycle Life, ARO stands for All Rods Out, HFP stands for Hot Full Power (100% RATED THERMAL POWER),

HFP vessel average temperature is 592 °F.

2.4.4 The Revised Predicted near-EOL 300 ppm MTC shall be calculated using the algorithm from Technical Specification 6.9.1.6.b.l0:

Revised Predicted MTC = Predicted MTC + AFD Correction - 3 pcm/°F If the Revised Predicted MTC is less negative than the COLR Section 2.4.3 limit and all of the benchmark data contained in the surveillance procedure are met, then an MTC measurement in accordance with S.R. 4.1.1.3b is not required.

2.5 ROD INSERTION LIMITS (Specification 3.1.3.5 and 3.1.3.6):

2.5.1 All banks shall have the same Full Out Position (POP) of either 256 or 259 steps withdrawn.

2.5.2 The Control Banks shall be limited m physical insertion as specified in. Figure 5.

2.5.3 Individual Shutdown, bank rods are fully withdrawn when the Bank Demand Indication is at the FOP and the Rod Group Height Limitmg Condition for Operation is satisfied (T.S. 3.1.3.1).

Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 5 of 16 2.6 AXIAL FLUX DIFFERENCE (Specification 3.2.1):

2.6.1 AFD limits as required by Technical Specification 3.2.1 are determined by Constant Axial Offset Control (CAOC) Operations with an AFD target band of+5, -10%.

2.6.2 The AFD shall be maintained within the ACCEPTABLE OPERATION portion of Figure 6, as required by Technical Specifications.

2.7 HEAT FLUX HOT CHANNEL FACTOR (Specification 3.2.2):

2.7.1 F^TP =2.55.

2.7.2 K(Z) is provided in Figure 7.

2.7.3 The Fxy limits for RATED THERMAL POWER (F^p) within specific core planes shall be:

2.7.3.1 Less than or equal to 2.102 for all cycle bumups for all core planes containing Bank "D" control rods, and 2.7.3.2 Less than or equal to the appropriate core height-dependent value from Table 1 for all mirodded core planes.

2.7.3.3 PFxy=0.2.

These Fxy limits were used to confirm that the heat flux hot channel factor FQ(Z) will be limited by Technical Specification 3.2.2 assuming the most-limitmg axial power distributions expected to result for the msertion and removal of Control Banks C and D during operation, mcludmg the accompanying variations in the axial xenon and power distributions, as described in WCAP-8385. Therefore, these Fxy limits provide assurance that the mitial conditions assumed m the LOCA analysis are met, along with the ECCS acceptance criteria of 10 CFR 50.46.

2.7.4 Core Power Distribution Measurement Uncertainty for the Heat Flux Hot Channel Factor 2.7.4.1 If the Power Distribution Monitoring System (PDMS) is operable, as defmed m the Technical Requirements Manual Section 3.3.3.12, the core power distribution measurement imcertamty (UFQ) to be applied to the FQ(Z) and Fxy(Z) using the PDMS shall be calculated by:

UFQ = (1.0 + (UQ/IOO))*UE Where:

UQ = Uncertainty for power peaking factor as defined in Equation 5-19 fi-om the document referenced by Technical Specification 6.9.1.6.b.ll UE== Engineering uncertainty factor of 1.03.

This uncertainty is calculated and applied automatically by the Power Distribution Monitoring System (PDMS).

Unit 2 Cycle 20

^u^ng^^ny Core Operating Limits Report Rev. 0 Page 6 of 16 2.7.4.2 If the moveable detector system is used, the core power distribution measurement uncertainty (UFQ) to be applied to the FQ(Z) and Fxy(Z) shall be calculated by:

UFQ = UQU*UE Where:

UQU = Base FQ measurement uncertainty of 1.05.

UE = Engineering uncertainty factor of 1.03.

2.8 ENTHALPY RISE HOT CHANNEL FACTOR (Specification 3.2.3):

2.8.1 Fg5p = 1.62 2.8.2 PFAH = 0.3 2.8.3 Core Power Distribution Measurement Uncertainty for the Enthalpy Rise Hot Channel Factor 2.8.3.1 If the Power Distribution Monitormg System (PDMS) is operable, as defmed in the Technical Requirements Manual Section 3.3.3.12, the core power disteibution measurement uncertainty (UFAH) to be applied to the F&

using the PDMS shall be the greater of:

UFAH=1.04 OR UFAH = 1.0 + (UAH/IOO)

Where:

UAH = Uncertainty for power peaking factor as defined in Equation 5-19 from the document referenced in Technical Specification 6.9.1.6.b.ll.

This uncertainty is calculated and applied automatically by the Power Disb-ibution Monitoring System.

2.8.3.2 If the moveable detector system is used, the core power distribution measurement uncertainty (UFAH) shall be:

UFAH=1.04

Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 7 of 16 2.9 DNB PARAMETERS (Specification 3.2.5):

2.9.1 The following DNB-related parameters shall be maintamed within the following limits (nominal values from Reference 3.1, as annotated below):l 2.9.1.1 Reactor Coolant System Tavg < 595 °F 2, 2.9.1.2 Pressurizer Pressure > 2200 psig3, 2.9.1.3 Minimum Measured Reactor Coolant System Flow > 403,000 gpm4.

3.0 REFERENCES

3.1 Letter from A. S. Ganey QVestmghouse) to R. F. Dumi (STPNOC), "South Texas Project Electric Generating Station Unit 2 Cycle 20 Final Reload Evaluation" NF-TG-18-12 (ST-UB-NOC-18003632) dated February 6,2018.

3.2 NUREG-1346, Technical Specifications, South Texas Project Unit Nos. 1 and 2.

3.3 STPNOC Calculation ZC-703 5, Rev. 2, "Loop Uncertainty Calculation for RCS Tavg Lastrumentation," Section 10.1.

3.4 STPNOC Calculation ZC-7032, Rev. 6, "Loop Uncertainty Calculation for Narrow Range Pressurizer Pressure Monitoring Instrumentation," Section 2.3, Page 9.

3.5 Letter from J. S Wyble (Westinghouse) to T. J. Jordan (STPNOC), "STP Nuclear Operating Company Units 1 & 2 Power Uprate PCWG Parameters," ST-WN-NOC-00-000072 dated December 1'5,2000, STI 31218644.

3.6 Letter from J. M. Ralston (Westinghouse) to D. F. Hoppes (STPNOC), "South Texas Project Electric Generating Station Units 1 and 2 Documentation of the fi(AI) Function in OTAT Setpomt Calculation," NF-TG-11-93 (ST-UB-NOC-11003215) dated November 10, 2011.

3.7 Document RSE-U2, Rev. 7, "Unit 2 Cycle 20 Reload Safety Evaluation and Core Operating Limits Report." (CR Action 16-15625-8)

A discussion of the processes to be used to take these readings is provided in the basis for Technical Specification 3.2.5.

Includes a 1.9 °F measurement uncertainty per Reference 3.3, Page 37.

Limit not applicable during either a Thermal Power ramp m excess of 5% ofRTP per minute or a Thermal Power step in excess of 10% RTP. Per Technical Specification 3.2.5 Bases, this includes a 10.7 psi measurement uncertainty as read on the QDPS display, which is bounded by the 9.6 psi averaged measurement calculated in Reference 3.4.

Includes the flow measurement uncertamty of 2.8% from Reference 3.5.

Nuclear Operating Company Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 8 of 16 Figure 1 Reactor Core Safety Limits - Four Loops in Operation Kl>

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Nuclear Operating Company Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 9 of 16 Figure 2 Required Shutdown Margin for Modes 3 & 4 7.0 6.0 5.0

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Nuclear Operating Company Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 11 of 16 Figure 4 MTC versus Power Level

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Nuclear Operating Company Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 12 of 16 FigureS Control Rod Insertion Limits* versus Power Level

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Nuclear Operating Company Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 13 of 16 l<uI0 Pt et Iu

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Nuclear Operating Company Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 14 of 16 Figure 7 K(Z) - Normalized FQ(Z) versus Core Height g3

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^I 1.2 1.1 1.0 -i 0.9 0.8 0.7 0.6 0.5

.§ 0.4 0.3 0.2 0.1 0.0 0 1 6789 Core Height (ft) 10 11 12 13 14

Unit 2 Cycle 20 Core Operating Lunits Report Rev. 0 Page 15 of 16 Table 1 (Part 1 of 2)

Unrodded Fxy for Each Core Height for Cycle Burnups Less Than 10000 MWD/MTU Core Height (Ft.)

14.0 13.8 13.6 13.4 13.2 13.0 12.8 12.6 12.4 12.2 12.0 11.8 11.6 11.4 11.2 11.0 10.8 10.6 10.4 10.2 10.0 9.8 9.6 9.4 9.2 9.0 8.8 8.6 8.4 8.2 8.0 7.8 7.6 7.4 7.2 7.0 Axial Point 1

2 3

4 5

6 7

8 9

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 Unrodded Fxy 7.129 5.560 3.993 2.657 2.474 2.191 2.096 2.097 2.049 1.987 1.948 1.960 2.005 1.992 1.944 1.913 1.905 1.894 1.869 1.881 1.931 1.944 1.881 1.859 1.863 1.865 1.872 1.893 1.959 2.023 1.987 1.936 1.931 1.941 1.936 1.925 Core Height (Ft.)

6.8 6.6 6.4 6.2 6.0 5.8 5.6 5.4 5.2 5.0 4.8 4.6 4.4 4.2 4.0 3.8 3.6 3.4 3.2 3.0 2.8 2.6 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 Axial Point 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Unrodded Fxy 1.979 2.046 2.017 1.943 1.906 1.939 1.948 1.948 1.993 2.065 2.084 2.027 1.959 1.975 1.977 1.963 1.969 2.017 2.051 1.995 1.944 1.947 1.951 1.922 1.897 1.915 1.916 1.824 1.750 1.780 2.068 2.763 3.936 5.599 8.325

Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 16 of 16 Table 1 (Part 2 of 2)

Unrodded Fxy for Each Core Height for Cycle Burnups Greater Than or Equal to 10000 MWD/MTU Core Height (Ft.)

14.00 13.80 13.60 13.40 13.20 13.00 12.80 12.60 12.40 12.20 12.00 11.80 11.60 11.40 11.20 11.00 10.80 10.60 10.40 10.20 10.00 9.80 9.60 9.40 9.20 9.00 8.80 8.60 8.40 8.20 8.00 7.80 7.60 7.40 7.20 7.00 Axial Point 1

2 3

4 5

6 7

8 9

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 Unrodded Fxy 6.389 5.096 3.803 2.698 2.550 2.273 2.120 2.061 1.999 1.977 1.976 2.016 2.073 2.069 2.023 2.004 2.015 2.019 2.021 2.056 2.116 2.144 2.104 2.068 2.084 2.096 2.103 2.120 2.174 2.222 2.180 2.138 2.138 2.149 2.158 2.164 Core Height (Ft.)

6.80 6.60 6.40 6.20 6.00 5.80 5.60 5.40 5.20 5.00 4.80 4.60 4.40 4.20 4.00 3.80 3.60 3.40 3.20 3.00 2.80 2.60 2.40 2.20 2.00 1.80 1.60 1.40 1.20 1.00 0.80 0.60 0.40 0.20 0.00 Axial Point 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Unrodded Fxy 2.208 2.253 2.219 2.152 2.114 2.105 2.093 2.077 2.097 2.137 2.135 2.073 2.023 2.018 2.005 1.988 1.989 2.029 2.056 1.998 1.943 1.927 1.899 1.872 1.894 1.941 1.971 1.950 1.963 2.074 2.444 3.182 4.307 5.855 8.547

Nuclear Operating Company South Texas Project Electric Genei-atlng Station P.O. Box 289 Wadsworth, Texas 77483 April 30, 2018 NOC-AE-18003563 10CFR 50.36 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 South Texas Project Unit 2 Docket No. STN 50-499 Unit 2 Cycle 20 Core Operating Limits Report In accordance with Technical Specification 6.9.1.6.d, STP Nuclear Operating Company submits the attached Core Operating Limits Report (COLR) for Unit 2 Cycle 20. The report covers the core design changes made during the 2RE19 refueling outage.

There are no commitments in this letter.

If there are any questions regarding this report, please contact Wendy Brost at (361) 972-8516 or me at (361) 972-7743.

^-?^>c^.

Roland F. Dunn

Manager, Nuclear Fuel & Analysis web

Attachment:

South Texas Project Unit 2 Cycle 20 Core Operating Limits Report, Revision 0 STI:34653746

NOC-AE-18003563 Page 2 of 2 ec:

(paper copy)

Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 1600 East Lamar Boulevard Arlington, TX 76011-4511 Lisa M. Regner Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North (08H04) 11555 Rockville Pike Rockvitle, MD 20852 NRC Resident Inspector U. S. Nuclear Regulatory Commission P.O. Box 289, Mail Code: MN116 Wadsworth.TX 77483

NOC-AE-18003563 Attachment Attachment South Texas Project Unit 2 Cycle 20 Core Operating Limits Report, Revision 0

Nuclear Operating Company SOUTH TEXAS PROJECT Unit 2 Cycle 20 CORE OPERATING LIMITS REPORT Revision 0 Core Operating Limits Report Page 1 of 16

Unit 2 Cycle 20

^y^ng^ny Core Operatmg Limits Report Rev. 0 Page 2 of 16 1.0 CORE OPERATING LIMITS REPORT This Core Operatmg Limits Report for STPEGS Unit 2 Cycle 20 has been prepared in accordance with the requirements of Technical Specification 6.9.1.6. The core operating limits have been developed usm^

the NRC-approved methodologies specified in Technical Specification 6.9.1.6.

The Technical Specifications afifected by this report are:

SAFETY UMITS LIMITING SAFETY SYSTEM SETTINGS SHUTDOWN MARGIN MODERATOR TEMPERATURE COEFFICDENT LIMITS SHUTDOWN ROD INSERTION LIMITS CONTROL ROD INSERTION LIMITS AFD LIMITS HEAT FLUX HOT CHANNEL FACTOR NUCLEAR ENTHALPY RISE HOT CHANNEL FACTOR DNB PARAMETERS 2.0 OPERATING LIMITS The cycle-specific parameter limits for the specifications listed m Section 1.0 are presented below.

2.1 SAFETY LIMITS (Specification 2.1):

2.1.1 The combination of THERMAL POWER, pressurizer pressure, and the highest operating loop coolant temperatoe (Tavg) shall not exceed the limits shown in Figure 1.

2.2 LIMITING SAFETY SYSTEM SETTD^GS (Specification 2.2):

2.2.1 The Loop design flow for Reactor Coolant Flow-Low is 98,000 gpm.

1) 2)

3) 4)

5) 6)

7) 8)

9) 10) 2.1 2.2 3/4.1.1 3/4.1.1 3/4.1.3 3/4.1.3 3/4.2.1 3/4.2.2 3/4.2.3 3/4.2.5

.1

.3

.5

.6

Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 3 of 16 2.2.2 The Over-temperature AT and Over-power AT setpoint parameter values are listed below:

Over-temperature AT Setpoint Parameter Values TI measured reactor vessel AT lead/lag time constant, TI = 8 sec T2 measured reactor vessel AT lead/lag time constant, T2 = 3 sec T3 measured reactor vessel AT lag time constant, TS = 2 sec T4 measured reactor vessel average temperature lead/lag time constant, n = 28 sec T5 measured reactor vessel average temperah.ire lead/lag time constant, TS== 4 sec T6 measured reactor vessel average temperature lag time constant, T6 = 2 sec Ki Overtemperature AT reactor faip setpoint, Ki = 1.14 K.2 Overtemperature AT reactor trip setpoint Tavg coefficient, K2 = 0.028/°F K.3 Overtemperature AT reactor trip setpoint pressure coefficient, KB = 0.00143/psi T Nominal full power Tavg, T'< 592.0 °F P' Nominal RCS pressure, P'== 223 5 psig fi(AT) is a function of the indicated difference between top and bottom detectors of the power-range neutron ion chambers; with gains to be selected based on measured instrument response during plant startup tests such that:

(1) For qi - qb between -70% and +8%, fi(AT) = 0, where qi and qb are percent RATED THERMAL POWER in the top and bottom halves of the core respectively, and qi + qb is total THERMAL POWER in percent of RATED THERMAL POWER; (2) For each percent that qi - qb is more negative than -70%, the AT Trip Setpoint shall be automatically reduced by 0.0% of its value at RATED THERMAL POWER; and (3) For each percent that qi - qb is more positive than +8%, the AT Trip Setpoint shall be automatically reduced by 2.65% of its value at RATED THERMAL POWER.

(Reference 3.6 and Section 4.4.1.2 of Reference 3.7)

Over-power AT Setpoint Parameter Values TI measured reactor vessel AT lead/lag time constant, TI = 8 sec T2 measured reactor vessel AT lead/lag time constant, T2 = 3 sec T3 measured reactor vessel AT lag time constant, TS = 2 sec T6 measured reactor vessel average temperature lag time constant, T6== 2 sec T7 Time constant utilized in the rate-lag compensator for Tavg, T? = 10 sec K4 Overpower AT reactor trip setpoint, K4 = 1.08 Ks Overpower AT reactor trip setpoint Tavg rate/lag coefficient, Ks = 0.02/°F for increasing average temperature, and KS = 0 for decreasing average temperature K.6 Overpower AT reactor trip setpoint Tavg heatip coefficient K6 =0.002/OFforT>T",and K6 = OforT^ T" T" Indicated fall power Tavg, T"$ 592.0 °F f2(AT) = 0 for all (AT)

Unit 2 Cycle 20

^^op^ng^^ny ^^ Operating Limits Report Rev. 0 Page 4 of 16 2.3 SHUTDOWN MARGIN (Specification 3.1.1.1):

The SHUTDOWN MARGIN shall be:

2.3.1 Greater than 1.3% Ap for MODES 1 and 2*

  • See Special Test Exception 3.10.1 2.3.2 Greater than the limits in Figure 2 for MODES 3 and 4.

2.3.3 Greater than the limits m Figure 3 for MODE 5.

2.4 MODERATOR TEMPERATURE COEFFICDENT (Specification 3.1.1.3):

2.4.1 The BOL, ARO, MTC shall be less positive than the limits shown in Figure 4.

2.4.2 The EOL, ARO, HFP, MTC shall be less negative than -62.6 pcm/°F.

2.4.3 The 300 ppm, ARO, HFP, MTC shall be less negative than -53.6 pcm/°F (300 ppm Swveillaace Limit).

Where: BOL stands for Begiiming-of-Cycle Life, EOL stands for End-of-Cycle Life, ARO stands for All Rods Out, HFP stands for Hot Full Power (100% RATED THERMAL POWER),

HFP vessel average temperature is 592 °F.

2.4.4 The Revised Predicted near-EOL 300 ppm MTC shall be calculated using the algorithm from Technical Specification 6.9.1.6.b.l0:

Revised Predicted MTC = Predicted MTC + AFD Correction - 3 pcm/°F If the Revised Predicted MTC is less negative than the COLR Section 2.4.3 limit and all of the benchmark data contained in the surveillance procedure are met, then an MTC measurement in accordance with S.R. 4.1.1.3b is not required.

2.5 ROD INSERTION LIMITS (Specification 3.1.3.5 and 3.1.3.6):

2.5.1 All banks shall have the same Full Out Position (POP) of either 256 or 259 steps withdrawn.

2.5.2 The Control Banks shall be limited m physical insertion as specified in. Figure 5.

2.5.3 Individual Shutdown, bank rods are fully withdrawn when the Bank Demand Indication is at the FOP and the Rod Group Height Limitmg Condition for Operation is satisfied (T.S. 3.1.3.1).

Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 5 of 16 2.6 AXIAL FLUX DIFFERENCE (Specification 3.2.1):

2.6.1 AFD limits as required by Technical Specification 3.2.1 are determined by Constant Axial Offset Control (CAOC) Operations with an AFD target band of+5, -10%.

2.6.2 The AFD shall be maintained within the ACCEPTABLE OPERATION portion of Figure 6, as required by Technical Specifications.

2.7 HEAT FLUX HOT CHANNEL FACTOR (Specification 3.2.2):

2.7.1 F^TP =2.55.

2.7.2 K(Z) is provided in Figure 7.

2.7.3 The Fxy limits for RATED THERMAL POWER (F^p) within specific core planes shall be:

2.7.3.1 Less than or equal to 2.102 for all cycle bumups for all core planes containing Bank "D" control rods, and 2.7.3.2 Less than or equal to the appropriate core height-dependent value from Table 1 for all mirodded core planes.

2.7.3.3 PFxy=0.2.

These Fxy limits were used to confirm that the heat flux hot channel factor FQ(Z) will be limited by Technical Specification 3.2.2 assuming the most-limitmg axial power distributions expected to result for the msertion and removal of Control Banks C and D during operation, mcludmg the accompanying variations in the axial xenon and power distributions, as described in WCAP-8385. Therefore, these Fxy limits provide assurance that the mitial conditions assumed m the LOCA analysis are met, along with the ECCS acceptance criteria of 10 CFR 50.46.

2.7.4 Core Power Distribution Measurement Uncertainty for the Heat Flux Hot Channel Factor 2.7.4.1 If the Power Distribution Monitoring System (PDMS) is operable, as defmed m the Technical Requirements Manual Section 3.3.3.12, the core power distribution measurement imcertamty (UFQ) to be applied to the FQ(Z) and Fxy(Z) using the PDMS shall be calculated by:

UFQ = (1.0 + (UQ/IOO))*UE Where:

UQ = Uncertainty for power peaking factor as defined in Equation 5-19 fi-om the document referenced by Technical Specification 6.9.1.6.b.ll UE== Engineering uncertainty factor of 1.03.

This uncertainty is calculated and applied automatically by the Power Distribution Monitoring System (PDMS).

Unit 2 Cycle 20

^u^ng^^ny Core Operating Limits Report Rev. 0 Page 6 of 16 2.7.4.2 If the moveable detector system is used, the core power distribution measurement uncertainty (UFQ) to be applied to the FQ(Z) and Fxy(Z) shall be calculated by:

UFQ = UQU*UE Where:

UQU = Base FQ measurement uncertainty of 1.05.

UE = Engineering uncertainty factor of 1.03.

2.8 ENTHALPY RISE HOT CHANNEL FACTOR (Specification 3.2.3):

2.8.1 Fg5p = 1.62 2.8.2 PFAH = 0.3 2.8.3 Core Power Distribution Measurement Uncertainty for the Enthalpy Rise Hot Channel Factor 2.8.3.1 If the Power Distribution Monitormg System (PDMS) is operable, as defmed in the Technical Requirements Manual Section 3.3.3.12, the core power disteibution measurement uncertainty (UFAH) to be applied to the F&

using the PDMS shall be the greater of:

UFAH=1.04 OR UFAH = 1.0 + (UAH/IOO)

Where:

UAH = Uncertainty for power peaking factor as defined in Equation 5-19 from the document referenced in Technical Specification 6.9.1.6.b.ll.

This uncertainty is calculated and applied automatically by the Power Disb-ibution Monitoring System.

2.8.3.2 If the moveable detector system is used, the core power distribution measurement uncertainty (UFAH) shall be:

UFAH=1.04

Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 7 of 16 2.9 DNB PARAMETERS (Specification 3.2.5):

2.9.1 The following DNB-related parameters shall be maintamed within the following limits (nominal values from Reference 3.1, as annotated below):l 2.9.1.1 Reactor Coolant System Tavg < 595 °F 2, 2.9.1.2 Pressurizer Pressure > 2200 psig3, 2.9.1.3 Minimum Measured Reactor Coolant System Flow > 403,000 gpm4.

3.0 REFERENCES

3.1 Letter from A. S. Ganey QVestmghouse) to R. F. Dumi (STPNOC), "South Texas Project Electric Generating Station Unit 2 Cycle 20 Final Reload Evaluation" NF-TG-18-12 (ST-UB-NOC-18003632) dated February 6,2018.

3.2 NUREG-1346, Technical Specifications, South Texas Project Unit Nos. 1 and 2.

3.3 STPNOC Calculation ZC-703 5, Rev. 2, "Loop Uncertainty Calculation for RCS Tavg Lastrumentation," Section 10.1.

3.4 STPNOC Calculation ZC-7032, Rev. 6, "Loop Uncertainty Calculation for Narrow Range Pressurizer Pressure Monitoring Instrumentation," Section 2.3, Page 9.

3.5 Letter from J. S Wyble (Westinghouse) to T. J. Jordan (STPNOC), "STP Nuclear Operating Company Units 1 & 2 Power Uprate PCWG Parameters," ST-WN-NOC-00-000072 dated December 1'5,2000, STI 31218644.

3.6 Letter from J. M. Ralston (Westinghouse) to D. F. Hoppes (STPNOC), "South Texas Project Electric Generating Station Units 1 and 2 Documentation of the fi(AI) Function in OTAT Setpomt Calculation," NF-TG-11-93 (ST-UB-NOC-11003215) dated November 10, 2011.

3.7 Document RSE-U2, Rev. 7, "Unit 2 Cycle 20 Reload Safety Evaluation and Core Operating Limits Report." (CR Action 16-15625-8)

A discussion of the processes to be used to take these readings is provided in the basis for Technical Specification 3.2.5.

Includes a 1.9 °F measurement uncertainty per Reference 3.3, Page 37.

Limit not applicable during either a Thermal Power ramp m excess of 5% ofRTP per minute or a Thermal Power step in excess of 10% RTP. Per Technical Specification 3.2.5 Bases, this includes a 10.7 psi measurement uncertainty as read on the QDPS display, which is bounded by the 9.6 psi averaged measurement calculated in Reference 3.4.

Includes the flow measurement uncertamty of 2.8% from Reference 3.5.

Nuclear Operating Company Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 8 of 16 Figure 1 Reactor Core Safety Limits - Four Loops in Operation Kl>

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Nuclear Operating Company Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 9 of 16 Figure 2 Required Shutdown Margin for Modes 3 & 4 7.0 6.0 5.0

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Nuclear Operating Company Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 11 of 16 Figure 4 MTC versus Power Level

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Nuclear Operating Company Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 12 of 16 FigureS Control Rod Insertion Limits* versus Power Level

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Nuclear Operating Company Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 13 of 16 l<uI0 Pt et Iu

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Nuclear Operating Company Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 14 of 16 Figure 7 K(Z) - Normalized FQ(Z) versus Core Height g3

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+.1u Jrth Ml JU s^

^I 1.2 1.1 1.0 -i 0.9 0.8 0.7 0.6 0.5

.§ 0.4 0.3 0.2 0.1 0.0 0 1 6789 Core Height (ft) 10 11 12 13 14

Unit 2 Cycle 20 Core Operating Lunits Report Rev. 0 Page 15 of 16 Table 1 (Part 1 of 2)

Unrodded Fxy for Each Core Height for Cycle Burnups Less Than 10000 MWD/MTU Core Height (Ft.)

14.0 13.8 13.6 13.4 13.2 13.0 12.8 12.6 12.4 12.2 12.0 11.8 11.6 11.4 11.2 11.0 10.8 10.6 10.4 10.2 10.0 9.8 9.6 9.4 9.2 9.0 8.8 8.6 8.4 8.2 8.0 7.8 7.6 7.4 7.2 7.0 Axial Point 1

2 3

4 5

6 7

8 9

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 Unrodded Fxy 7.129 5.560 3.993 2.657 2.474 2.191 2.096 2.097 2.049 1.987 1.948 1.960 2.005 1.992 1.944 1.913 1.905 1.894 1.869 1.881 1.931 1.944 1.881 1.859 1.863 1.865 1.872 1.893 1.959 2.023 1.987 1.936 1.931 1.941 1.936 1.925 Core Height (Ft.)

6.8 6.6 6.4 6.2 6.0 5.8 5.6 5.4 5.2 5.0 4.8 4.6 4.4 4.2 4.0 3.8 3.6 3.4 3.2 3.0 2.8 2.6 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 Axial Point 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Unrodded Fxy 1.979 2.046 2.017 1.943 1.906 1.939 1.948 1.948 1.993 2.065 2.084 2.027 1.959 1.975 1.977 1.963 1.969 2.017 2.051 1.995 1.944 1.947 1.951 1.922 1.897 1.915 1.916 1.824 1.750 1.780 2.068 2.763 3.936 5.599 8.325

Unit 2 Cycle 20 Core Operating Limits Report Rev. 0 Page 16 of 16 Table 1 (Part 2 of 2)

Unrodded Fxy for Each Core Height for Cycle Burnups Greater Than or Equal to 10000 MWD/MTU Core Height (Ft.)

14.00 13.80 13.60 13.40 13.20 13.00 12.80 12.60 12.40 12.20 12.00 11.80 11.60 11.40 11.20 11.00 10.80 10.60 10.40 10.20 10.00 9.80 9.60 9.40 9.20 9.00 8.80 8.60 8.40 8.20 8.00 7.80 7.60 7.40 7.20 7.00 Axial Point 1

2 3

4 5

6 7

8 9

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 Unrodded Fxy 6.389 5.096 3.803 2.698 2.550 2.273 2.120 2.061 1.999 1.977 1.976 2.016 2.073 2.069 2.023 2.004 2.015 2.019 2.021 2.056 2.116 2.144 2.104 2.068 2.084 2.096 2.103 2.120 2.174 2.222 2.180 2.138 2.138 2.149 2.158 2.164 Core Height (Ft.)

6.80 6.60 6.40 6.20 6.00 5.80 5.60 5.40 5.20 5.00 4.80 4.60 4.40 4.20 4.00 3.80 3.60 3.40 3.20 3.00 2.80 2.60 2.40 2.20 2.00 1.80 1.60 1.40 1.20 1.00 0.80 0.60 0.40 0.20 0.00 Axial Point 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Unrodded Fxy 2.208 2.253 2.219 2.152 2.114 2.105 2.093 2.077 2.097 2.137 2.135 2.073 2.023 2.018 2.005 1.988 1.989 2.029 2.056 1.998 1.943 1.927 1.899 1.872 1.894 1.941 1.971 1.950 1.963 2.074 2.444 3.182 4.307 5.855 8.547

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