NL-21-0962, Core Operating Limits Report, Cycle 24, Version 1

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Core Operating Limits Report, Cycle 24, Version 1
ML21299A196
Person / Time
Site: Vogtle Southern Nuclear icon.png
Issue date: 10/26/2021
From: Gayheart C
Southern Nuclear Operating Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-21-0962
Download: ML21299A196 (16)
v • d • e


Text

Cheryl A. Gayheart 3535 Colonnade Parkway Regulatory Affairs Director Birmingham, AL 35243 205 992 5316 cagayhea@southernco.com October 26, 2021 Docket No.: 50-424 NL-21-0962 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Vogtle Electric Generating Plant - Unit 1 Core Operating Limits Report, Cycle 24, Version 1 Ladies and Gentlemen:

In accordance with Technical Specifications (TS) 5.6.5.d for Vogtle Electric Generating Plant (VEGP), Southern Nuclear Operating Company (SNC) submits the VEGP Core Operating Limits Report (COLR) for Unit 1, Cycle 24, Version 1.

All the methods described in the documents listed in TS 5.6.5.b were used to develop the core operating limits contained in the COLR as described in this TS section. There were no additional methods used to develop the core operating limits contained in the COLR other than those described in the documents listed in TS 5.6.5.b. All methods used to determine the core operating limits contained in the COLR have NRC approval via a safety evaluation.

This letter contains no NRC commitments. If you have any questions, please contact Ryan Joyce at 205.992.6468.

Respectfully submitted, Cheryl A. Gayheart Regulatory Affairs Director CAG/kgl/cg

Enclosure:

VEGP Unit 1 COLR, Cycle 24, Version 1 cc: Regional Administrator NRR Project Manager - Vogtle 1 & 2 Senior Resident Inspector - Vogtle 1 & 2 RType: CVC7000

Vogtle Electric Generating Plant - Unit 1 Core Operating Limits Report, Cycle 24, Version 1 ENCLOSURE to NL-21-0962 VEGP Unit 1 COLR, Cycle 24, Version 1

VOGTLE ELECTRIC GENERATING PLANT (VEGP) UNIT 1 CYCLE 24 CORE OPERATING LIMITS REPORT Version 1 June 2021

CORE OPERATING LIMITS REPORT, VEGP UNIT 1 CYCLE 24 JUNE 2021 1.0 CORE OPERATING LIMITS REPORT This Core Operating Limits Report (COLR) for VEGP Unit 1 Cycle 24 has been prepared in accordance with the requirements of Technical Specification 5.6.5.

The Technical Requirement affected by this report is listed below:

13.1.1 SHUTDOWN MARGIN - MODES 1 and 2 The Technical Specifications affected by this report are listed below:

3.1.1 SHUTDOWN MARGIN - MODES 3, 4 and 5 3.1.3 Moderator Temperature Coefficient 3.1.5 Shutdown Bank Insertion Limits 3.1.6 Control Bank Insertion Limits 3.2.1 Heat Flux Hot Channel Factor - FQ(Z) 3.2.2 Nuclear Enthalpy Rise Hot Channnel Factor - FNH 3.2.3 Axial Flux Difference 3.9.1 Boron Concentration Page 1 of 13

CORE OPERATING LIMITS REPORT, VEGP UNIT 1 CYCLE 24 JUNE 2021 2.0 OPERATING LIMITS The cycle-specific parameter limits for the specifications listed in Section 1.0 are presented in the following subsections. These limits have been developed using NRC-approved methodologies including those specified in Technical Specification 5.6.5.

2.1 SHUTDOWN MARGIN - MODES 1 and 2 (Technical Requirement 13.1.1) 2.1.1 The SHUTDOWN MARGIN shall be greater than or equal to 1.30 percent k/k.

2.2 SHUTDOWN MARGIN - MODES 3, 4 and 5 (Specification 3.1.1) 2.2.1 The SHUTDOWN MARGIN shall be greater than or equal to the limits shown in Figures 1 and 2.

Page 2 of 13

CORE OPERATING LIMITS REPORT, VEGP UNIT 1 CYCLE 24 JUNE 2021 2.3 Moderator Temperature Coefficient (Specification 3.1.3) 2.3.1 The Moderator Temperature Coefficient (MTC) limits are:

The BOL/ARO/HZP-MTC shall be less positive than +0.7 x 10-4 k/k/°F for power levels up to 70% RTP with a linear ramp to 0 k/k/°F at 100% RTP.

The EOL/ARO/RTP-MTC shall be less negative than -5.35 x 10-4 k/k/°F. 1 2.3.2 The MTC Surveillance limits are:

The 300 ppm/ARO/RTP-MTC should be less negative than or equal to

-4.60 x 10-4 k/k/°F. 1 The revised predicted near-EOL 300 ppm MTC shall be calculated using Figure 6 and the following algorithm:

Revised Predicted MTC = Predicted MTC* + AFD Correction** + Predictive Correction***

where,

  • Predicted MTC is calculated from Figure 6 at the burnup corresponding to the measurement of 300 ppm at RTP conditions,
    • AFD Correction is the more negative value of:

{0 pcm/°F or (AFD

  • AFD Sensitivity)}

where: AFD is the measured AFD minus the predicted AFD from an incore flux map taken at or near the burnup corresponding to 300 ppm, AFD Sensitivity = 0.08 pcm/°F / AFD

      • Predictive Correction is -3 pcm/°F.

The 60 ppm/ARO/RTP-MTC should be less negative than -5.20 x 10-4 k/k/°F. 1 where: BOL stands for Beginning of Cycle Life ARO stands for All Rods Out HZP stands for Hot Zero THERMAL POWER EOL stands for End of Cycle Life RTP stands for RATED THERMAL POWER 1

Applicable for full-power T-average of 580.0 to 587.0 °F.

Page 3 of 13

CORE OPERATING LIMITS REPORT, VEGP UNIT 1 CYCLE 24 JUNE 2021 2.4 Shutdown Bank Insertion Limits (Specification 3.1.5) 2.4.1 The shutdown banks shall be withdrawn to a position greater than or equal to 225 steps.

2.5 Control Bank Insertion Limits (Specification 3.1.6) 2.5.1 The control rod banks shall be limited in physical insertion as shown in Figure 3.

2.6 Heat Flux Hot Channel Factor - FQ(Z) (Specification 3.2.1)

FQRTP 2.6.1 FQ ( Z ) K ( Z ) for P > 0.5 P

FQRTP FQ ( Z ) K ( Z ) for P 0.5 0.5 THERMAL POWER where: P=

RATED THERMAL POWER 2.6.2 FQRTP = 2.50 2.6.3 K(Z) is provided in Figure 4.

FQRTP K ( Z )

2.6.4 FQ ( Z ) for P > 0.5 P W (Z )

FQRTP K ( Z )

FQ ( Z ) for P 0.5 0.5 W ( Z )

2.6.5 W(Z) values are provided in Table 2.

2.6.6 The FQ(Z) penalty factors are provided in Table 1.

Page 4 of 13

CORE OPERATING LIMITS REPORT, VEGP UNIT 1 CYCLE 24 JUNE 2021 2.7 Nuclear Enthalpy Rise Hot Channel Factor - FNH (Specification 3.2.2) 2.7.1 H ( 1 + PFH (1 P ))

FNH FRTP THERMAL POWER where: P=

RATED THERMAL POWER 2.7.2 FRTP H = 1.65 2.7.3 PFH = 0.3 2.8 Axial Flux Difference (Specification 3.2.3) 2.8.1 The Axial Flux Difference (AFD) Acceptable Operation Limits are provided in Figure 5.

2.9 Boron Concentration (Specification 3.9.1) 2.9.1 The boron concentration shall be greater than or equal to 2000 ppm. 2 2

This concentration bounds the condition of keff 0.95 (all rods in less the most reactive rod) and subcriticality (all rods out) over the entire cycle. This concentration includes additional boron to address uncertainties and B10 depletion.

Page 5 of 13

CORE OPERATING LIMITS REPORT, VEGP UNIT 1 CYCLE 24 JUNE 2021 Table 1 FQ(Z) PENALTY FACTOR Burnup Penalty (MWD/MTU) Factor 0 1.0594 150 1.0594 368 1.0569 585 1.0538 803 1.0504 1020 1.0470 1238 1.0430 1456 1.0364 1673 1.0306 1891 1.0257 2108 1.0218 2326 1.0200 7766 1.0200 7983 1.0202 8201 1.0210 8418 1.0200 Notes:

1. The Penalty Factor, to be applied to FQ(Z) in accordance with SR 3.2.1.2, is the maximum factor by which FQ(Z) is expected to increase over a 39 EFPD interval (surveillance interval of 31 EFPD plus the maximum allowable extension not to exceed 25% of the surveillance interval per SR 3.0.2) starting from the burnup at which the FQ(Z) was determined.
2. Linear interpolation is adequate for intermediate cycle burnups.
3. For all cycle burnups outside the range of the table, a penalty factor of 1.0200 shall be used.

Page 6 of 13

CORE OPERATING LIMITS REPORT, VEGP UNIT 1 CYCLE 24 JUNE 2021 Table 2 RAOC W(Z)

Axial Elevation 150 4000 8000 12000 16000 20000 Point (feet) MWD/MTU MWD/MTU MWD/MTU MWD/MTU MWD/MTU MWD/MTU

  • 1-5 12.072 - 11.267 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 6 11.066 1.3733 1.4042 1.2807 1.2524 1.2279 1.2288 7 10.865 1.3592 1.3892 1.2714 1.2511 1.2252 1.2237 8 10.664 1.3419 1.3696 1.2569 1.2461 1.2119 1.2118 9 10.462 1.3243 1.3477 1.2420 1.2392 1.1946 1.2012 10 10.261 1.3032 1.3235 1.2331 1.2382 1.1967 1.1895 11 10.060 1.2799 1.2969 1.2245 1.2395 1.2029 1.1869 12 9.859 1.2544 1.2649 1.2132 1.2404 1.2071 1.1850 13 9.658 1.2448 1.2309 1.2046 1.2287 1.2063 1.1876 14 9.456 1.2433 1.2035 1.1971 1.2238 1.2078 1.1907 15 9.255 1.2406 1.1870 1.1866 1.2224 1.2059 1.1962 16 9.054 1.2314 1.1714 1.1819 1.2178 1.2049 1.2024 17 8.853 1.2250 1.1656 1.1769 1.2031 1.2024 1.2048 18 8.652 1.2208 1.1660 1.1767 1.1947 1.1963 1.2063 19 8.450 1.2213 1.1704 1.1829 1.1974 1.1982 1.2120 20 8.249 1.2174 1.1728 1.1860 1.2010 1.2074 1.2250 21 8.048 1.2228 1.1734 1.1872 1.2093 1.2212 1.2399 22 7.847 1.2252 1.1725 1.1868 1.2150 1.2324 1.2523 23 7.646 1.2247 1.1694 1.1842 1.2185 1.2412 1.2623 24 7.444 1.2221 1.1653 1.1805 1.2204 1.2483 1.2710 25 7.243 1.2164 1.1589 1.1740 1.2184 1.2510 1.2747 26 7.042 1.2087 1.1509 1.1659 1.2138 1.2505 1.2750 27 6.841 1.1995 1.1434 1.1568 1.2080 1.2483 1.2738 28 6.640 1.1883 1.1364 1.1493 1.2003 1.2439 1.2705 29 6.438 1.1766 1.1299 1.1417 1.1910 1.2372 1.2676 30 6.237 1.1653 1.1232 1.1343 1.1814 1.2294 1.2627 31 6.036 1.1534 1.1207 1.1260 1.1709 1.2204 1.2567 32 5.835 1.1452 1.1179 1.1215 1.1597 1.2100 1.2491 33 5.634 1.1390 1.1197 1.1196 1.1583 1.2034 1.2398 34 5.432 1.1386 1.1326 1.1259 1.1642 1.2035 1.2355 35 5.231 1.1448 1.1440 1.1366 1.1686 1.2082 1.2367 36 5.030 1.1521 1.1550 1.1463 1.1727 1.2118 1.2391 37 4.829 1.1589 1.1653 1.1557 1.1777 1.2138 1.2395 38 4.628 1.1651 1.1751 1.1643 1.1813 1.2141 1.2379 39 4.426 1.1706 1.1842 1.1724 1.1839 1.2128 1.2342 40 4.225 1.1750 1.1922 1.1794 1.1851 1.2100 1.2289 41 4.024 1.1782 1.1994 1.1858 1.1863 1.2060 1.2220 42 3.823 1.1823 1.2056 1.1910 1.1870 1.1995 1.2120 43 3.622 1.1888 1.2108 1.1949 1.1857 1.1912 1.1995 44 3.420 1.1950 1.2151 1.1982 1.1841 1.1822 1.1864 45 3.219 1.1992 1.2187 1.2002 1.1816 1.1741 1.1738 46 3.018 1.2056 1.2318 1.2057 1.1867 1.1750 1.1743 47 2.817 1.2141 1.2489 1.2211 1.1969 1.1846 1.1842 48 2.616 1.2276 1.2646 1.2408 1.2060 1.1952 1.1955 49 2.414 1.2436 1.2847 1.2606 1.2150 1.2057 1.2074 50 2.213 1.2608 1.3090 1.2806 1.2266 1.2162 1.2192 51 2.012 1.2778 1.3332 1.2999 1.2377 1.2253 1.2293 52 1.811 1.2946 1.3570 1.3186 1.2484 1.2340 1.2388 53 1.610 1.3103 1.3795 1.3366 1.2589 1.2431 1.2490 54 1.408 1.3253 1.4006 1.3535 1.2693 1.2525 1.2598 55 1.207 1.3395 1.4202 1.3693 1.2792 1.2619 1.2708 56 1.006 1.3526 1.4379 1.3837 1.2888 1.2714 1.2823
  • 57-61 0.805 - 0.000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000

These W(Z) values are consistent with Figure 5, and are valid over the HFP Tavg temperature range from 580.0 to 587.0°F.

Page 7 of 13

CORE OPERATING LIMITS REPORT, VEGP UNIT 1 CYCLE 24 JUNE 2021 FIGURE 1 REQUIRED SHUTDOWN MARGIN FOR MODES 3 AND 4 (FOUR LOOPS FILLED AND VENTED AND AT LEAST ONE REACTOR COOLANT PUMP RUNNING)

Page 8 of 13

CORE OPERATING LIMITS REPORT, VEGP UNIT 1 CYCLE 24 JUNE 2021 FIGURE 2 REQUIRED SHUTDOWN MARGIN FOR MODES 4 AND 5 (MODE 4 WHEN FIGURE 1 NOT APPLICABLE)

Page 9 of 13

CORE OPERATING LIMITS REPORT, VEGP UNIT 1 CYCLE 24 JUNE 2021 FIGURE 3 ROD BANK INSERTION LIMITS VERSUS % OF RATED THERMAL POWER (Fully Withdrawn*)

Fully withdrawn shall be the condition where control rods are at a position within the interval 225 and 231 steps withdrawn.

NOTE: The Rod Bank Insertion Limits are based on the control bank withdrawal sequence A, B, C, D and a control bank tip-to-tip distance of 115 steps.

Page 10 of 13

CORE OPERATING LIMITS REPORT, VEGP UNIT 1 CYCLE 24 JUNE 2021 FIGURE 4 K(Z) - NORMALIZED FQ(Z) AS A FUNCTION OF CORE HEIGHT Page 11 of 13

CORE OPERATING LIMITS REPORT, VEGP UNIT 1 CYCLE 24 JUNE 2021 FIGURE 5 AXIAL FLUX DIFFERENCE LIMITS AS A FUNCTION OF % RATED THERMAL POWER FOR RAOC Page 12 of 13

CORE OPERATING LIMITS REPORT, VEGP UNIT 1 CYCLE 24 JUNE 2021 FIGURE 6 PREDICTED HFP 300 PPM MTC VS CYCLE BURNUP

-28.0 Moderator Temperature Coefficient

-28.5 (pcm/°F)

-29.0

-29.5

-30.0 16000 17000 18000 19000 20000 21000 Cycle Burnup (MWD/MTU)

Cycle Burnup Moderator Temperature Coefficient (MWD/MTU) (pcm/°F) 16000 -28.24 17000 -28.54 18000 -28.81 19000 -29.12 20000 -29.37 21000 -29.62 Page 13 of 13

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