L-2024-140, Cycle 28 Core Operating Limits Report

Cycle 28 Core Operating Limits Report

ML24227A985
Person / Time
Site:	Saint Lucie
Issue date:	08/14/2024
From:	Rasmus P Florida Power & Light Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
L-2024-140
Download: ML24227A985 (1)

Text

U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-00001 Re:

St. Lucie Nuclear Plant, Unit 2 Docket 50-389 August 14, 2024 Cycle 28 Core Operating Limits Report L-2024-140 10 CFR 50.36 Pursuant to St. Lucie Unit 2 Technical Specification (TS) 5.6.3, Florida Power & Light Company (FPL) is submitting the Core Operating Limits Report (COLR) for operating Cycle 28.

Should you have any questions regarding this submittal, please contact Mr. Kenneth Mack, Senior Manager, Licensing and Regulatory Compliance, at 561-904-3635.

Sincerely,

/Y~

Paul Rasmus General Manager, Regulatory Affairs

Enclosure:

St. Lucie Unit 2, Cycle 28 Core Operating Limits Report cc:

USNRC Regional Administrator, Region II USNRC Project Manager, St. Lucie Nuclear Plant USNRC Resident Inspector, St. Lucie Nuclear Plant Florida Power & Light Company 6501 S. Ocean Drive, Jensen Beach, FL 34957

Prepared by:

Verified by:

ST. LUCIE UNIT 2, CYCLE 28 CORE OPERATING LIMITS REPORT Revision O

~

07/26/2024 E. A. Rernandez Date

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07/26/2024 R. Hunter Date L-2024-140 Enclosure Approved by: ~**

0R.Norring f/21/Z)j Date St Lucie Unit 2 Cycle 28 COLR Rev.O Page 1 of 13

Table of Contents Description 1.0 Introduction 2.0 Core Operating Limits 2.1 Moderator Temperature Coefficient (MTC) 2.2 Control Element Assembly (CEA) Alignment 2.3 Regulating CEA Insertion Limits 2.4 Linear Heat Rate (LHR) and Axial Shape Index (ASI) 2.5 TOTAL INTEGRATED RADIAL PEAKING FACTOR (FrT) 2.6 RCS Pressure, Temperature and Flow Departure from Nucleate Boiling (DNB) Limits 2.7 Boron Concentration 2.8 SHUTDOWN MARGIN (SOM)- Tavg Greater Than 200 °F Page 3

4 4

4 4

4 5

5 5

6 2.9 SHUTDOWN MARGIN (SOM) - Tavg Less Than or Equal To 200 °F 6

2.10 Reactor Core Safety Limits (SLs) 6 List of Tables and Figures Title Page Table 3.2-2 DNB Margin Limits 7

Fig 3.1-1a Allowable Time To Realign CEA vs. Initial F?

8 Fig 3.1-2 CEA Group Insertion Limits vs. THERMAL POWER 9

Fig 3.2-1 Allowable Peak Linear Heat Rate vs. Burnup 10 Fig 3.2-2 AXIAL SHAPE INDEX vs. Maximum Allowable Power Level 11 Fig 3.2-3 Allowable Combinations of THERMAL POWER and F?

12 Fig 3.2-4 AXIAL SHAPE INDEX Operating Limits vs. THERMAL POWER 13 St. Lucie Unit 2 Cycle 28 COLR Rev.O Page 2 of 13

1.0 INTRODUCTION

This CORE OPERATING LIMITS REPORT (COLR) describes the cycle-specific parameter limits for operation of St. Lucie Unit 2. It contains the limits for the following as provided in Section 2.

Moderator Temperature Coefficient (MTC),

Control Element Assembly (CEA) Alignment, Regulating CEA Insertion Limits, Linear Heat Rate (LHR) and Axial Shape Index (ASI),

TOTAL INTEGRATED RADIAL PEAKING FACTOR - Fl RCS Pressure, Temperature and Flow Departure from Nucleate Boiling (DNB)

Limits, Boron Concentration, SHUTDOWN MARGIN (SOM) - Tavg Greater Than 200 °F, SHUTDOWN MARGIN (SOM) - Tavg Less Than or Equal To 200 °F, Reactor Core Safety Limits (SLs).

This report also contains the necessary figures which give the limits for the above listed parameters.

Terms appearing in capitalized type are DEFINED TERMS as defined in Section 1.0 of the Technical Specifications.

This report is prepared in accordance with the requirements of Technical Specification 5.6.3.

St. Lucie Unit 2 Cycle 28 COLR Rev.O Page 3 of 13

2.0 CORE OPERATING LIMITS 2.1 Moderator Temperature Coefficient (TS 3.1.3)

The moderator temperature coefficient (MTC) shall be less negative than -32 pcm/°F at RATED THERMAL POWER (RTP).

The maximum positive limit shall be:

a. +5 pcm/°F with THERMAL POWER :5 70% RTP, and

b. +5 pcm/°F with THERMAL POWER at 70% RTP with a linear decrease to O pcm/°F at 100% RTP.

2.2 Control Element Assembly (CEA) Alignment (TS 3.1.4)

The time constraints for full power operation with one full-length CEA misaligned from any other CEA in its group by more than 15 inches are shown in Figure 3.1-1a.

2.3 Regulating CEA Insertion Limits (TS 3.1.6 and 3.1. 7)

The regulating CEA groups shall be limited to the withdrawal sequence and to the insertion limits shown on Figure 3.1-2, with CEA insertion between the Long Term Steady State Insertion Limits and the Power Dependent Insertion Limits restricted to:

a.

~ 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> per 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> interval,

b.

< 5 Effective Full Power Days per 30 Effective Full Power Days, and

c.

< 14 Effective Full Power Days per 365 EFPD.

2.4 Linear Heat Rate (TS 3.2.1) and Axial Shape Index (TS 3.2.4)

The linear heat rate shall not exceed the limits shown on Figure 3.2-1.

The AXIAL SHAPE INDEX power dependent control limits are shown on Figure 3.2-2.

Excore Detector Monitoring System During operation, with the linear heat rate (LHR) being monitored by the Excore Detector Monitoring System, the AXIAL SHAPE INDEX required by TS 3.2.1 shall be maintained within the limits of Figure 3.2-2.

lncore Detector Monitoring System During operation, with the linear heat rate being monitored by the lncore Detector Monitoring System, the Local Power Density alarm setpoints shall be adjusted to less than or equal to the limits shown on Figure 3.2-1.

St. Lucie Unit 2 Cycle 28 COLR Rev.O Page 4 of 13

The AXIAL SHAPE INDEX required by TS 3.2.4 shall be maintained within the limits shown on Figure 3.2-4.

The instrumentation AXIAL SHAPE INDEX (Y1) used for the trip and pretrip signals in the reactor protection system is the AXIAL SHAPE INDEX value (YE) modified by an appropriate multiplier (A) and a constant (B) to determine the true core axial power distribution for that channel (Y1 =AYE+ B). Where YE is the power level detected by the lower excore nuclear instrument detectors (L) less the power level detected by the upper excore nuclear instrument detectors (U), divided by the sum of these power levels, [YE = (L-U) / (L +U)].

2.5 TOTAL INTEGRATED RADIAL PEAKING FACTOR - Fr1 (TS 3.2.2)

The calculated value of Fl shall be limited to.:: 1.65.

The power dependent Fl limits are shown on Figure 3.2-3.

2.6 RCS Pressure, Temperature and Flow Departure from Nucleate Boiling (DNB) Limits (TS 3.4.1)

The following DNB-related parameters shall be maintained within the limits shown on Table 3.2-2:

a.

Cold Leg Temperature

b.

Pressurizer Pressure 2.7 Boron Concentration (TS 3.9.1)

With the reactor vessel head closure bolts less than fully tensioned or with the head removed, the boron concentration of all filled portions of the Reactor Coolant System, the refueling canal, and the refueling canal shall be maintained uniform and sufficient to ensure that the MORE RESTRICTIVE of the following reactivity conditions is met:

a.

Either a Keff of 0.95 or less, OR

b.

A boron concentration of greater than or equal to 1900 ppm.

2.8 SHUTDOWN MARGIN-Tava Greater Than 200 °F (TS 3.1.1)

The SHUTDOWN MARGIN shall be greater than or equal to 3600 pcm.

2.9 SHUTDOWN MARGIN - Tava Less Than or Equal To 200 °F (TS 3.1.1)

The SHUTDOWN MARGIN shall be greater than or equal to 3000 pcm.

St. Lucie Unit 2 Cycle 28 COLR Rev.O Page 5 of 13

2.10 Reactor Core Sls (TS 2.1)

The fuel melt limit is defined as [(2790 - 17.9 x P - 3.2 x 8) x 1.8 + 32] °F, where Pis the maximum weight percent of Gadolinia (%) and B is the maximum pin burnup (GWD/MTU).

St. Lucie Unit 2 Cycle 28 COLR Rev.O Page 6 of 13

Table 3.2-2 DNB MARGIN LIMITS PARAMETER FOUR REACTOR COOLANT PUMPS OPERATING Cold Leg Temperature (narrow Range) 535°F** ~ T ~ 551°F Pressurizer Pressure*

2225 psia ~ PPzR ~ 2350 psia**

Limit not applicable during either a THERMAL POWER ramp increase in excess of 5% per minute of RA TED THERMAL POWER or a THERMAL POWER step increase of greater than 10% of RATED THERMAL POWER.

Applicable only if power level ~ 70% of RA TED THERMAL POWER.

St. Lucie Unit 2 Cycle 28 COLR Rev.O Page 7 of 13

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FIGURE 3.1-2 CEA Group Insertion Limits vs. THERMAL POWER St. Lucie Unit 2 Cycle 28 COLR Rev.O Page 9 of 13

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FIGURE 3.2-1 Allowable Peak Linear Heat Rate vs. Burnup St. Lucie Unit 2 Cycle 28 COLR Rev.O Page 10 of 13

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FIGURE 3.2-2 0.5 0.7 AXIAL SHAPE INDEX vs. Maximum Allowable Power Level Note: AXIAL SHAPE INDEX limits for Linear Heat Rate when using Excore Detector Monitoring System St. Lucie Unit 2 Cycle 28 COLR Rev.O Page 11 of 13

1.1 1.0 0.9 0.8 Allowable Fraction 0_7 of RATED THERMAL POWER (P}

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(The expression specified in the Figure may be used for F? at all power levels)

St. Lucie Unit 2 Cycle 28 COLR Rev.O Page 12 of 13

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(AXIAL SHAPE INDEX limits for DNB)

St. Lucie Unit 2 Cycle 28 COLR Rev.O Page 13 of 13 0.7