WBL-21-013, of Cycle 4 Core Operating Limits Report

of Cycle 4 Core Operating Limits Report

ML21077A067
Person / Time
Site:	Watts Bar
Issue date:	03/18/2021
From:	Anthony Williams Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
WBL-21-013
Download: ML21077A067 (13)

Text

l TENNESSEE VALLEY AUTHORITY Post Office Box 2000, Spring City, Tennessee 37381 WBL-21-013 March 18, 2021 10 CFR 50.4 ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 2 Facility Operating License No. NPF-96 NRC Docket No. 50-391

Subject:

REVISION 1 OF THE WATTS BAR UNIT 2 CYCLE 4 CORE OPERATING LIMITS REPORT (COLR)

In accordance with Watts Bar Nuclear Plant (WBN) Technical Specifications Section 5.9.5.d, Tennessee Valley Authority (TVA) is submitting Revision 1 of the WBN Unit 2, Cycle 4 Core Operating Limits Report (COLR).

There are no new regulatory commitments contained in this letter or the enclosure. Should you have questions regarding this submittal, please contact Tony Brown, WBN Site Licensing Manager, at (423) 365-7720 .

. Williams IV Site Vice President Watts Bar Nuclear Plant

U.S. Nuclear Regulatory Commission Page2 WBL-21-013 March 18, 2021

Enclosure:

Watts Bar Nuclear Plant, Unit 2, Cycle 4 Core Operating Limits Report Revision 1 March 2021 cc (Enclosure):

NRC Regional Administrator - Region II NRR Project Manager NRC Senior Resident Inspector

ENCLOSURE Watts Bar Nuclear Plant, Unit 2, Cycle 4 Core Operating Limits Report Revision 1 March 2021

QA Record L36 210302 800 WATTS BAR NUCLEAR PLANT, UNIT 2, CYCLE 4 CORE OPERATING LIMITS REPORT Revision 1 March 2021 Prepared

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Date of PORC Affected Revision Aooroval Paoes Reason for Revision 0 10/23/2020 All Initial issue 1,4,9,10 Updated W(z) values on Table A.1 and removed 1 See Above TableA.3 Unit2 Cycle4 WATTS BAR Page 1 oflO Revision 1

1.0 CORE OPERATING LIMITS REPORT This Core Operating Limits Report (COLR) for Watts Bar Unit 2 Cycle 4 has been prepared in accordance with the requirements of the Technical Specifications (TS) 5.9.5.

The Technical Specifications affected by this report are listed below:

3.1.4 Moderator Temperature Coefficient (MTC) 3.1.5 Rod Group Alignment Limits 3.1.6 Shutdown Bank Insertion Limits 3.1.7 Control Bank Insertion Limits 3.2.1 Heat Flux Hot Channel Factor (FQ(Z))

3.2.2 Nuclear Enthalpy Rise Hot Channel Factor (F,mN) 3.2.3 Axial Flux Difference (AFD) 3.9.1 Boron Concentration 2.0 OPERATING LIMITS The cycle-specific parameter limits for the specifications listed in section l .O are presented in the following subsections. These limits have been developed using the NRC approved methodologies specified in the Technical Specifications Section 5.9.5.

The following abbreviations are used in this section:

BOL Beginning of Cycle Life ARO All Rods Out HZP Hot Zero Thermal Power EOL End of Cycle Life RTP Rated Thermal Power Unit2 Cycle 4 WATTS BAR Page2 of IO Revision I

2.1 MODERATOR TEMPERATURE COEFFICIENT - MTC (LCO 3.1.4) 2.1.1 The MTC limits are:

The ARO/HZP - MTC shall be less positive than or equal to 0 Ak/k/°F (upper limit).

With the measured BOL/ARO/HZP- MTC more positive than -2.12 x 10-5 Ak/k/°F (as-measured MTC limit), establish control rod withdrawal limits to ensure the MTC remains less positive than or equal to OAfdk/°F (upper limit) for all times in core life.

The EOL/ARO/RTP - MTC shall be less negative than or equal to

-4.50 x 104 &/k/°F (lower limit).

2.1.2 The 300 ppm surveillance limit is:

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

-3.75 x 104 Afc/k/°F.

2.1.3 The 60 ppm surveillance limit is:

The measured 60 ppm /ARO/RTP-MTC should be less negative than or equal to

-4.28 X 104 &/k/°F.

2.2 SHUTDOWN MARGIN - SDM (LCO 3.1.S, 3.1.6, 3.1.7) 2.2.1 For TS 3. 1.5, SOM shall be?: 1.6% .Afc/k in MODE I and MODE 2.

2.2.2 For TS 3.1.6, SOM shall be?: 1.6% llk/k in MODE 1 and MODE 2.

2.2.3 For TS 3.1.7, SOM shall be?: 1.6% Afc/k in MODE 1 and MODE 2 with kerr?: 1.0.

2.3 SHUTDOWN BANK INSERTION LIMITS (LCO 3.1.6) 2.3.1 The shutdown banks shall be withdrawn to a position greater than or equal to 225 steps withdrawn.

2.4 CONTROL BANK INSERTION LIMITS (LCO 3.1.7) 2.4.1 The control banks are fully withdrawn or shall be limited in physical insertion as shown in Figure 1.

2.4.2 Each control bank shall be considered fully withdrawn from the core at greater than or equal to 225 steps.

2.4.3 The control banks shall be operated in sequence by withdrawal of Bank A, Bank B, Bank C, and Bank D. The control banks shall be sequenced in reverse order upon insertion.

Unit2 Cycle 4 WATTS BAR Page 3 ofl0 Revision I

2.4.4 Each control bank not fully withdrawn from the core shall be operated with the following overlap as a function of park position.

Park Position (steps) Bank Overlap (steps) Bank Difference (steps) 225 109 116 226 110 116 227 111 116 228 112 116 229 113 116 230 114 116 231 115 116 2.S HEAT FLUX HOT CHANNEL FACTOR - FQ(Z) (LCO 3.2.1)

FQ(Z) ~ [CFQ/P]

• K(Z) for P > 0.5 FQ(Z) ~ [CFQ/ 0.5]

• K(Z) for P::;; 0.5 Where P = Thermal Power / Rated Thermal Power 2.5.1 CFQ = 2.50 2.5.2 K(Z) is provided in Figure 2.

2.5.3 FQw(Z) = FQc(Z)

• W(Z)/P for P > 0.5 FQw(Z) = FQc(Z)

• W(Z)/0.5 for P :5 0.5 where: W(Z) values are provided in Table A. l.

This table provides sufficient information to determine W(Z) versus core height for all cycle burnups.

2.5.4 The W(Z) values provided by Table A.I may be used when the part power surveillance is performed using the fixed incore detector system.

2.5.5 FQw(Z) Penalty Factor The FQW(Z) penalty factor is provided in Table A.2.

Unit2 Cycle4 WATTS BAR Page 4 of 10 Revision I

2.6 NUCLEAR ENTHALPY RISE HOT CHANNEL FACTOR-FAnN (LCO 3.2.2) where P ::::: Thermal Power / Rated Thermal Power EmRTP = 1.65 for RFA-2 fuel, and PF = 0.3

2. 7 AXIAL FLUX DIFFERENCE - AFD (LCO 3.2.3) 2.7.1 The AFD limits for Cycle 4 arc provided in Figure 3.

2.8 REFUELING BORON CONCENTRATION (LCO 3.9.1) 2.8.1 The refueling boron concentration shall be ~ 2300 ppm.

3.0 NUMBER OF TPBARS IN REACTOR CORE (TS 4.2.l) 3.0.1 There are 544 tritium producing burnable absorber rods (TPBARs) in the reactor core for Cycle 4.

Unit2 Cycle 4 WATTS BAR Page 5 of 10 Revision 1

200 1175 E

3: 150 t

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0.0 0.2 0.4 0.6 0.8 1.0 FRACTION OF RATED THERMAL POWER Figure 1 Control Bank Insertion Limits Versus Thermal Power Four Loop Operation

• FuUy withdrawn region shall be the condition where shutdown and control banks are at a position within the interval of~ 225 and~ 231 steps withdrawn.

Unit2 Cycle4 WATTS BAR Page6 of 10 Revision I

1.2 1.1 1

0.9 0.8 cu

! 0.7 A.

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"'0 0.6 Core Height K(Z)

-~ 0.000 1.000 I

.. 0.5 6.000 12.000 1.000 1.000 0

z 0.4 0.3 0.2 0.1 0

0 1 2 3 4 5 6 7 8 9 10 11 12 Core Height (feet)

Figure2 K(Z) - Normalized FQ(Z) as a Function of Core Height Unit2 Cycle4 WATTS BAR Page 7 of 10 Revision l

120 110 i <-12. 100) 1 1 (7, 100) I 100 I \

I 90 I

Acceptable Operation I '\\

80 LJ Unacceptable Operation r-*** II \ I Unacceptable Operation t

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-50 -40 -30 -20 -10 0 10 20 30 40 Flux Difference (A I) %

Figure3 Axial Flux Difference Acceptable Operation Limits as a function of Rated Thermal Power (RAOC)

Unit2 Cycle 4 WATTS BAR Page 8 of 10 Revision I

TableA.1 RAOCW Z) Surveillance Factors Height 150 2000 8000 12000 14000 16000 (Ft) (MWD/MTU) (MWD/MTU) <MWD!MTU) (MWD/MTU) (MWD/MTU) (MWD/MTU) 12.0720 1.0000 1.0000 1.0000 l.0000 l.0000 l.0000 11.8708 l.0000 LOOOO 1.0000 1.0000 1.0000 1.0000 11.6696 l.0000 1.0000 1.0000 1.0000 1.0000 1.0000 11.4684 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 11.2672 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 11.0660 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 10.8648 1.2448 1.2607 1.2818 1.2400 l.2528 1.2621 10.6636 1.2318 1.2401 1.2398 1.2212 1.2258 1.2348 10.4624 1.2230 1.2278 1.2261 1.2082 1.2194 1.2242 10.2612 1.2102 1.2077 1..2134 1.1938 1.2005 1.2116 10JJ600 1.1982 1.1919 1.1974 1.1802 1.1829 1.1949 9.8588 1.1869 1.1775 1.1834 1.1710 1.1759 1.1825 9.6576 1.1854 1.1780 1.1760 1.1676 1.1760 1.1857 9.4564 1.1850 1.1753 1.1731 1.1807 1.1764 1.1877 9.2552 1.1843 1.1738 1.1752 1.1800 1.1756 1.1893 9.0540 1.1820 1.1761 1.1781 1.1816 1.1809 1.1946 8.8528 1.1871 1.1808 1.1795 1.1855 1.1815 1.1956 8.6516 1.1941 1.1818 1.1814 1.1978 1.1833 1.1979 8.4504 1.2016 1.1851 1.1905 1.2133 1.1944 1.2086 8.2492 1.2059 1.1882 1.2036 1.2262 1.2124 1.2272 8.0480 1.2077 1.1913 1.2116 1.2365 1.2273 1.2425 7.8468 1.2145 1.1944 1.2186 1.2443 1.2381 l.2560 7.6456 1.2182 1.1975 1.2221 1.2489 1.2470 1.2651 7.4444 1.2198 1.1988 1.2253 1.2515 1.2538 1.2728 7.2432 1.2192 1..1979 1.2234 1.2509 1.2575 1.2770 7.0420 1.2172 1.1954 1.2213 1.2481 1.2579 1.2775 6.8408 1.2132 1.1916 1.2164 1.2431 1.2574 1.2762 6.6396 l.2070 1.1856 1.2109 1.2364 1.2533 1.2720 6.4384 l.1998 1.1786 1.2033 1.2314 1.2477 1.2673 6.2372 1.1918 1.1768 1.1943 1.2244 1.2402 1.2594 6.0360 1.1827 1.1770 1.1829 1.2151 1.2314 1.2490 5.8348 1.1787 1.1741 1.1707 1.2046 1.2184 1.2364 5.6336 1.1734 1.1714 1.1632 l.1920 1.2060 1.2223 5.4324 1.1705 1.1700 1.1605 1.1785 1.1914 1.2054 5.2312 1.1696 1.1672 1.1587 1.1777 1.1856 1.1946 5.0300 1.1694 1.1635 1.1590 1.1752 1.1840 1.1910 4.8288 1.1692 1.1580 1.1595 1.1726 1.1807 1.1871 4.6276 1.1689 1.1564 1.1605 1.1682 1.1756 1.1822 4.4264 1.1678 1.1561 1.1596 1.1638 1.1705 1.1762 4.2252 1.1649 1.1550 1.1585 1.1585 1.1666 1.1712 4.0240 1.1624 1.1533 1.1565 1.1542 1.1629 1.1661 3.8228 1.1589 l.1514 1.1544 1.1511 1.1582 1.1599 3.6216 1.1580 1.1495 1.1512 1.1509 1.1525 1.1525 3.4204 1.1626 1.1529 1.1515 1.1543 1.1477 1.1465 3.2192 1.1672 1.1578 l.1559 1.1580 1.1478 1.1454 3.0180 1.1766 1.1722 1.1665 1.1606 1.1507 1.1515 2.81.68 1.1963 1.1958 1.1846 1.1727 1.1622 1.1691 2.6156 1.2172 1.2184 1.2056 1.1910 1.1796 1.1881 2.4144 1.2374 1.2422 1.2242 1.2080 1.1956 1.2067 2.2132 1.2578 l.2643 1.2437 1.2254 1.2129 1.2248 2.0120 1.2773 1.2874 1.2627 1.2418 1.2289 1.2420 1.8108 1.2973 1.3082 1.2804 1.2574 1.2434 1.2582 1.6096 1.3143 1.3290 1.2973 1.2715 1.2578 1.2736 1.4084 1.3287 1.3458 1.3130 1.2838 1.2701 1.2877 1.2072 1.3428 1.3601 1.3270 1.2946 1.2812 1.2988 1.0060 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 0.8048 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 0.6036 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 0.4024 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 0.2012 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 0.0000 l.0000 1.0000 1.0000 1.0000 1.0000 1.0000 Unit2 Cycle 4 WATTS BAR Page9 of 10 Revision I

TableA.2 FQw(z) Penalty Factor Cycle Burnup F:J' (Z) Penalty (MWD/MTU) Factor 8296 1.0200 8485 1.0215 8675 1.0231 8864 1.0247 9054 1.0261 9243 1.0250 9433 l.0234 9622 1.0218 9812 1.0202 10001 1.0200 Note:

1. The Penalty Factor, which is applied to FQw(Z) for compliance with Surveillance Requirement 3.2. l.2, is the maximum factor by which FQw(Z) is expected to increase per 31. Effective Full Power Days (EFPD) starting from the bumup at which the FQ w(Z) was determined. This Penalty Factor is applicable for the set ofW(Z) Surveillance Factors provided in Table A.I.

Unit2 Cycle 4 WATTS BAR Page 10 of lO Revision 1