NOC-AE-19003692, Unit 2 Cycle 21 Core Operating Limits Report

Unit 2 Cycle 21 Core Operating Limits Report

ML19311C640
Person / Time
Site:	South Texas
Issue date:	11/07/2019
From:	Dunn R South Texas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NOC-AE-19003692
Download: ML19311C640 (20)

Text

Nuclear Operating Company South Texas Project Electric Genei-atlng Station 1>0. Box 289 Wadsworth, Texas 77483 November 7, 2019 NOC-AE-19003692 10 CFR 50.36 STI:34941013 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 21 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 21. The report covers the core design changes made during the 2RE20 refueling outage.

There are no commitments in this letter.

If there are any questions regarding this report, please contact All Albaaj at (361) 972-8949 or me at (361) 972-7743.

^-^

Roland F. Dunn Jr General Manager, Engineering aa

Attachment:

South Texas Project Unit 2 Cycle 21 Core Operating Limits Report, Revision ec: Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 1600 E. Lamar Boulevard Arlington, TX 76011-4511

NOC-AE-19003692 Attachment U2C21-0 Nuclear Operating Company SOUTH TEXAS PROJECT Unit 2 Cycle 21 CORE OPERATmG LBiITS REPORT Revision 0 Core Operating Limits Report Page 1 of 17

Unit 2 Cycle 21

^^p^ng^^ny ^^ Operating Limits Report Rev. 0 Page 2 of 17 1.0 CORE OPERATING UMTTS REPORT Ttus Core Operating Limits Report for STPEGS Unit 2 Cycle 21 has been prepared in accordance with the requirements of Technical Specification 6.9,1.6, The core operating limits have been developed using the NRC-approved methodologies specified m Technical Specification 6.9,1 ,6.

The Technical Specifications affected by this report are;

1) 2.1 SAFETY LIMITS

2) 2,2 LIMITING SAFETY SYSTEM SETTINGS

3) 3/4.1.1,1 SHUTDOWN MARGIN

4) 3/4,1,1,3 MODERATOR TEMPERATURE COEFFICIENT LIMITS

5) 3/4,1,3,5 SHUTDOWN ROD INSERTION LIMITS

6) 3/4.1,3,6 CONTROL ROD INSERTION LIMITS

7) 3/4,2.1 AFD LIMITS

8) 3/4,2.2 HEAT FLUX HOT CHANNEL FACTOR

9) 3/4,2.3 NUCLEAR ENTHALPY RISE HOT CHANNEL FACTOR

10) 3/4.2.5 DNB PARAMETERS 2.0 OPERA.TDNG LIMITS The cycle-specific parameter limits for the specifications listed in Section 1,0 are presented below.

2.1 SAFETY LIMITS (Specification 2.1):

2.1,1 The combmation of THERMAL POWER, pressurizer pressure, and the highest operating loop coolant temperature (Tavg) shall not exceed the lunits shown in. Figure 1, 2.2 LBHTING SAFETY SYSTEM SETTINGS (Specification 2.2);

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

Unit 2 Cycle 21 Core Operating Limits Report Rev, 0 Page 3 of 17 2,2.2 The Over-temperature AT and Over-power AT setpomt parameter values are listed below:

Over-temperature AT Setpoint Parameter Values TI measured reactor vessel AT lead/lag time constant, 11 = 8 sec T;2 measured reactor vessel AT lead/lag time constant, xz = 3 sec 1:3 measured reactor vessel AT lag tune constant, 13 = 2 sec T4 measured reactor vessel average temperat.u'e lead/lag time constant, T4 = 28 sec T5 measured reactor vessel average temperature lead/lag time constant, TS = 4 sec T6 measured reactor vessel average temperature lag time constant, TS = 2 sec Ki Overtemperature AT reactor tnp setpomt, Ki = 1.14 K.2 Overtemperature AT reactor tnp setpoint Tavg coef&cient, Kz = 0.028/°F Ks Overtemperature AT reactor trip setpoint pressure coefficient, Ks= 0.00143/psi T' Nominal full power Tavg, T'^ 592,0 °F P' Nominal RCS pressure, P' = 2235 psig fi(AI) is a function of the mdicated difference between top and bottom detectors of the power-range neutron ion chambers; with gaios to be selected based on measured instrument response durmg plant startup tests suchfliat:

(1) For q; - qb between -70% and 4-8%, fi(AI) = 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 Setpomt 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°/o of its value at RATED THERMAL POWER, (Reference 3,6 and Section 4.4.1,2 of Reference 3,7)

Over-power AT Setpoinf Parameter Values TI measured reactor vessel AT lead/lag time constant, TI = 8 sec xi measured reactor vessel AT lead/lag tune constant, xz = 3 sec 1:3 measured reactor vessel AT lag time constant, -cs == 2 sec T$ measured reactor vessel average temperature lag time constant, T6 = 2 sec T? Time constant utilized in the rate-lag compensator for Tavg, T;? == 10 sec K4 Overpower AT reactor trip setpoint, K4 = 1,08 K.5 Overpower AT reactor tap setpoint Tavg rate/lag coef&cient, Ks = 0,02/°F for increasing average temperature, and Ks = 0 for decreasing average temperature K^ Overpower AT reactor tnp setpoint Tavg heatup coefficient Kg = 0,002/°F for T > T", and Ks = OforT^ T" T" Indicated faU power Tavg, T"< 592.0 °F f2(AI) = 0 for all (AI)

Unit 2 Cycle 21

^^p^ng^^y Cwe Operating Limits Report Rev. 0 Page 4 of 17 2.3 SHUTDOWN MARGIN (Specification 3.1.1.1);

The SHUTDOWN MARGIN shall be; 2.3.1 Greaterfhan 1,3% Ap for MODES 1 and 2*

• See Special Test Exception 3.10,1 2,3,2 Greater than the limits m Figure 2 for MODES 3 and 4, 2.3,3 Greater than the limits in Figure 3 for MODE 5.

2.4 MODERATOR TEMPERATURE COEFFICIENT (Specification 3.1.1.3):

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

2.4,2 The EOL, ARO, HFP, MTC shall be less negative than -2.6 pcm/°F, 2.4.3 The 300 ppm, ARO, HFP, MTC shall be less negative than -53,6 pcm/°F (300 ppm Swveillance Limit),

Where; BOL stands for Begmniag-of-Cycle Life, EOL stands for End-of-CycIe 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 &om Tedmical Specification 6,9,1,6,b,10:

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 LBUTS (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 258 or 259 steps withdrawn.

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

2,5.3 Individual Shutdown bank rods are fully withdrawn when the Bank Demand Indication is at the POP and the Rod Group Height Lumtmg Condition for Operation is satisfied (T.S, 3.1,3,1).

Unit 2 Cycle 21

^y^na^^ny ^ore Operating Limits Report Rev, 0 Page 5 of 17 2.6 AXIAL FLUX DIFFERENCE (Specification 3.2.1):

2,6.1 AFD Umits as required by Techmcal 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 withui 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 m Figure 7, 2.7.3 The Fxy limits for RATED THERMAL POWER (F^p) wifhin specific core planes shall be:

2.7,3,1 Less than or equal to 2.1 02 for all cycle bumups for all core planes contairmg 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 unrodded core planes.

2,7.3.3 PFxy=0,2.

These Fxy limits were used to confirm, that the heat flux hot channel factor PQ(Z) will be limited by Technical Specification 3.2.2 assuming the most-lunitmg axlal power distributions expected to result for the insertion and removal of Control Banks C and D during operation, includmg fhe accompanying vanations in. the axial xenon and power distributions, as described ia WCAP-8385, Therefore, these Fxy limits provide assurance that the initial conditions assumed in. the LOCA analysis axe met, along with the ECCS acceptance criteria of 10 CFR 50,46.

2.7.4 The Fxy limits from Section 2,7,3 above are not applicable in the following core plane regions as measured in percent of core height from the bottom of the fuel:

2.7.4.1 Upper and lower core regions as presented ia Table 2, and 2.7.4.2 Grid plane regions as presented in Table 2, and 2.7.4,3 Core plane regions withm +/- 2% of core height (+/-3.36 inches) about the

. bank demand position, of the bank "D" control rods.

2,7,5 Core Power Distnbution Measurement Uncertainty for the Heat Flux Hot Channel Factor 2.7,5,1 If the Power Distribution Momtormg System (PDMS) is operable, as defined in the Technical Requirements Manual Section 3.3.3.12, the core power distribution measurement uncertainty (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:

Unit 2 Cycle 21 Core Operating Limits Report Rev, 0 Page 6 of 17 UQ == Uncertamty for power peaking factor as defined in Equation 5-19 fi-om fhe document referenced by Technical Specification 6.9,1.6/b.U UE= Engineering uncertainty factor of 1.03.

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

2,7,5,2 If the moveable detector system is used, the core power distribution measurement imcertainty (UFQ) to be applied to the FQ(Z) and Pxy(Z) shall be calculated by:

UFQ = UQU UE Where:

UQU = Base FQ measurement uncertainty of 1.05, UE = Engineering uncertamty factor of 1,03, 2.8 ENTHALPY MSE HOT CHAJWfEL FACTOR (Specification 3.2.3):

2.8.1 fW = 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 Monitoring System (PDMS) is operable, as defined in the Technical Requirements Manual Section 3,3.3.12, the core power distribution measurement uncertainty (UPAH) to be applied to the P&i using fhe PDMS shall be the greater of; UTAH =1.04 OR UFAH==I.O+(UAH/IOO)

Where; UAH = Uncertainty for power peaking factor as defined in Equation 5-19 from the document referenced in Technical Specification 6,9,l,6.b,ll.

This uncertainty is calculated and applied automaticaUy by the Power Distribution Monitormg System.

2.8,3.2 If the moveable detector system is used, the core power distnbution measurement uncertainty (U-p&n) shall be; UFAH=1.04

Unit 2 Cycle 21 Nj^opei^tng^m^ny Core Operating Limits Report Rev. 0 Page 7 of 17 2.9 DNB PARAMETERS (Specification 3.2.5);

2,9,1 The foUowmg DNB-related parameters shaU be mamtamed withm the following limits (nonunal values from Reference 3.1, as annotated below):

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 Coolaat System Flow > 403,000 gpm4.

3.0 REFERENCES

3.1 Letter fi-om A. S. Ganey (Westmghouse) to R, F, Durm (STPNOC), "South Texas Project Electric Generating Station Unit 2 Cycle 21 Final Reload Evaluation" NP-TG-19-047 (ST-UB-NOC-19003731) dated August 12,2019, 3.2 NUKEG-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 Instmmentation," Section 10.1.

3.4 STTNOC Calculation ZC-7032, Rev, 6, "Loop Uncertainty Calculation for Narrow Range Pressurizer Pressure Momtoring iDstrumentation," Section 2.3, Page 9.

3.5 Letter fi-om J. S Wyble (Westmghouse) to T, J, Jordan (STPNOC), "STP Nuclear Operating Company Units 1 & 2 Power Uprate PCWG Parameters," ST-WN-NOC-00-000072 dated December 15,2000, STI 31218644, 3.6 Letter fiom J. M, Ralston (Westmghouse) to D, F, Hoppes (STPNOC), "South Texas Proj ect Electdc Generating Station Units 1 and 2 Documentation of the fi(AI) Function m OTAT Setpoint Calculation," NF-TG-11 -93 (ST-UB-NOC-11003215) dated November 10,2011, 3.7 Document RSE-U2, Rev, 9, "Unit 2 Cycle 21 Reload Safety Evaluation and Core Operating Limits Report." (CR Action 18-11887-56)

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 uncertamty per Reference 3.3, Page 37, Limit not applicable during either a Thermal Power ramp in excess of 5% ofRTP per mim-rte or a Themial Power step m 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 .

Unit 2 Cycle 21 Nuclear Operating Company Core Operating Limits Report Rev. 0 Page 8 of 17 Figure 1 Reactor Core Safety Limits - Four Loops in Operation

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Unit 2 Cycle 21 NuclearOperating Company Core Operating Limits Report Rev, 0 Page 9 of 17 Figure 2 Required Shutdown Margin for Modes 3 & 4 7,0 6,0 5,0 0

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Unit 2 Cycle 21 Nuclear Oparating Company Core Operating Limits Report Rev. 0 Page 11 of 17 Figure 4 MTC versus Power Level 6.0 Fnacceptab]

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Unit 2 Cycle 21 Nuclear Operating Company Core Operating Lunits Report Rev. 0 Page 12 of 17 Figures Conft-ol Rod Insertion Limits* versus Power Level l3,25$)iU2St^Ov<t i2;253)) UlSt^Ovfrf

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Unit 2 Cycle 21 Nuclear Operating Company Core Operating Limits Report Rev, 0 Page 13 of 17 Figure 6 AFD Limits versus Power Level I

sr Nuclear Operating Company Unit 2 Cycle 21 Core Operating Limits Report Rev, 0 Page 14 of 17 Figure?

K(Z) - Normalized FQ(Z) versus Core Height

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0 1 2 34 5 6 78 9 10 11

• 12 13 14 Core Height (ft)

Unit 2 Cycle 21 Core Operating Limits Report Rev. 0 Page 15 of 17 Table 1 (Part 1 of 2)

Unrodded Fxy for Each Core Height for Cycle Burnups Less Than 9000 MWD/MTU (Subject to the exclusion zones of COLR Section 2.7.4)

Core Height Axial Unrodded Core Height Axial Unrodded (Ft.) Point Fxy (Ft.) Point Fxy 14.0 1 7.287 6,8 37 1,968 13.8 2 5.678 6.6 38 2.033 13,6 3 4.072 6.4 39 2.010 13.4 4 2.701 6,2 40 1.944 13.2 5 2,510 6.0 41 1.898 13,0 6 2.224 5,8 42 1.932 12.8 7 2.131 5,6 43 1.940 12.6 8 2.129 5.4 44 1.941 12.4 9 2.087 5.2 45 1,985 12.2 10 2.035 5.0 46 2.055 12.0 11 2.009 4,8 47 2,066 11.8 12 2.027 4.6 48 2,004 11.6 13 2.059 4,4 49 1,934 11.4 14 2.048 4.2 50 1.946 11,2 15 2.005 4,0 51 1,954 11.0 16 1.966 3.8 52 1,946 10.8 17 1.956 3.6 53 1.959 10,6 18 1.944 3.4 54 2.010 10.4 19 1,922 3,2 55 2,050 10.2 20 1.933 3.0 56 1.998 10,0 21 1.964 2.8 57 1,947 9,8 22 1.969 2,6 58 1,955 9.6 23 1.930 2.4 59 1.963 9.4 24 1.906 2.2 60 1,956 9.2 25 1.909 2.0 61 1.957 9.0 26 1.893 1.8 62 1,983 8.8 27 1.892 1,6 63 1,983 8.6 28 1.906 1.4 64 1,897 8.4 29 1.960 1,2 65 1.835 8.2 30 2.035 1,0 66 1,871 8.0 31 1.987 0.8 67 2.179 7.8 32 1.918 0,6 68 2.918 7.6 33 1.907 0.4 69 4.159 7,4 34 1,934 0,2 70 5.903 7,2 35 1,933 0,0 71 8.815 7,0 36 1.919

Unit 2 Cycle 21 Core Operating Limits Report Rev, 0 Page 16 of 17 Table 1 (Part 2 of 2)

Unrodded Fxy for Each Core Height for Cycle Burnups Greater Than or Equal to 9000 MWD/MTU (Subject to the exclusion zones ofCOLR Section 2,7.4)

Core Height Axial Unrodded Core Height Axial Unrodded (Ft.) Point J?xy (Ft.) Point Fxy 14.00 1 6,448 6.80 37 2.198 13.80 2 5.133 6.60 38 2.243 13.60 3 3.818 6.40 39 2.208 13.40 4 2,694 6,20 40 2.141 13.20 5 2.544 6.00 41 2.103 13,00 6 2,268 5,80 42 2.095 12.80 7 2,120 5.60 43 2,083 12.60 8 2.067 5.40 44 2,067 12.40 9 2.019 5.20 45 2.088 12.20 10 1,976 5.00 46 2.129 12.00 11 1,971 4.80 47 2.127 11,80 12 2.013 4.60 48 2,066 11,60 13 2.075 4.40 49 2.016 11.40 14 2.068 4,20 50 2,012 11.20 15 2.029 4.00 51 2.001 11.00 16 1.988 3.80 52 1,986 10.80 17 2.011 3,60 53 1.990 10.60 18 2.020 3.40 54 2,030 10,40 19 2.022 3,20 55 2.059 10.20 20 2,055 3,00 56 2,002 10.00 21 2.114 2.80 57 1,949 9.80 22 2.140 2.60 58 1,930 9.60 23 2.097 2.40 59 1,909 9.40 24 2.047 2.20 60 1,882 9,20 25 2.060 2.00 61 1.901 9.00 26 2.080 1,80 62 1,945 8.80 27 2.087 1.60 63 1,976 8.60 28 2.106 1,40 64 1,955 8.40 29 2.168 1,20 65 1,969 8,20 30 2.224 1,00 66 2.082 8.00 31 2.178 0.80 67 2.454 7,80 32 2.132 0.60 68 3,200 7.60 33 2.133 0,40 69 4.337 7,40 34 2.144 0.20 70 5.894 7.20 35 2.152 0,00 71 8,647 7.00 36 2.155

Unit 2 Cycle 21 Core Operating Limits Report Rev, 0 Page 17 of 17 Table 2 Core and 5rid Plam ?xy Exclusion Zones Core Core Core Core Axial Height Height Axial Height Height Point _(^L _(%}_ Top/Bottom Grid Poiat (in.) (%) Top/Bottom Grid 1 168,0 100.0 Excluded 37 81,6 48.6 2 165,6 98.6 Excluded 38 79.2 47,1 Excluded 3 163.2 97,1 Excluded 39 76.8 45,7 Excluded 4 160.8 95,7 Excluded 40 74,4 44.3 5 158,4 94.3 Excluded 41 72,0 42.9 6 156.0 92.9 Excluded 42 69,6 41.4 7 153,6 91.4 Excluded 43 67,2 40.0 8 151,2 90,0 Excluded 44 64,8 38.6 9 148.8 88.6 45 62,4 37.1 10 146.4 87.1 46 60,0 35,7 Excluded 11 144,0 85,7 47 57.6 34,3 Excluded 12 141.6 84.3 48 55,2 32.9 Excluded 13 139.2 82.9 Excluded 49 52.8 31.4 14 136.8 81.4 Excluded 50 50,4 30,0 15 134,4 80,0 Excluded 51 48,0 28.6 16 132,0 78,6 52 45,6 27.1 17 129.6 77,1 53 43,2 25,7 18 127.2 75,7 54 40.8 24.3 Excluded 19 124.8 74,3 55 38,4 22.9 Excluded 20 122.4 72,9 56 36,0 21,4 Excluded 21 120,0 71.4 Excluded 57 33,6 20.0 22 117.6 70.0 Excluded 58 31.2 18,6 23 115,2 68,6 Excluded 59 28.8 17,1 24 112.8 67.1 60 26,4 15.7 25 110,4 65.7 61 24,0 14,3 26 108,0 64,3 62 21.6 12.9 Excluded 27 105.6 62.9 63 19.2 11.4 Excluded 28 103,2 61.4 64 16.8 10.0 Excluded 29 100.8 60.0 Excluded 65 14,4 8.6 Excluded 30 98.4 58.6 Excluded 66 12.0 7.1 Excluded 31 96,0 57,1 Excluded 67 9,6 5.7 Excluded 32 93,6 55.7 68 7,2 4.3 Excluded 33 91.2 54,3 69 4.8 2.9 Excluded 34 88,8 52.9 70 2,4 1,4 Excluded 35 86,4 51,4 71 0,0 0.0 Excluded 36 84,0 50,0