ML11186A863

Cycle 18, Core Operating Limits Report

ML11186A863
Person / Time
Site:	Sequoyah
Issue date:	07/01/2011
From:	Krich R Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L36 110613 803
Download: ML11186A863 (14)

Text

Tennessee Valley Authority 1101 Market Street, LP 3R Chattanooga, Tennessee 37402-2801 R. M. Krich Vice President Nuclear Licensing July 1, 2011 10 CFR 50.4 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Sequoyah Nuclear Plant, Unit 2 Facility Operating License No. DPR-79 NRC Docket No. 50-328

Subject:

Sequoyah Nuclear Plant, Unit 2, Cycle 18, Core Operating Limits Report The purpose of this letter is to submit the Sequoyah Nuclear Plant (SQN), Unit 2, Cycle 18, Core Operating Limits Report (COLR), Revision 0, as required by SQN Technical Specification (TS) 6.9.1.14.c. TS 6.9.1.14.c requires the COLR to be provided to the NRC within 30 days after cycle startup (i.e., Mode 2) for each reload cycle. SQN, Unit 2, entered Mode 2 on June 22, 2011, for the current reload cycle.

Therefore, the Tennessee Valley Authority is submitting the enclosed COLR prior to July 22, 2011.

There are no new regulatory commitments in this letter. Should you have any questions concerning this submittal, please contact Dan Green at (423) 751-8423.

Respectfully, -

R. M. Krich

Enclosure:

Sequoyah Nuclear Plant, Unit 2, Cycle 18, Core Operating Limits Report, Revision 0 cc (Enclosure):

NRC Regional Administrator- Region II NRC Senior Resident Inspector - Sequoyah Nuclear Plant , V printed on recycled paper

ENCLOSURE SEQUOYAH NUCLEAR PLANT UNIT 2, CYCLE 18 CORE OPERATING LIMITS REPORT REVISION 0

QA RECORD L36 110613 803 SEQUOYAH UNIT 2 CYCLE 18 CORE OPERATING LIMITS REPORT REVISION 0 June 2011 Prepared by:

PWR Fuel Engineering Date Verified by:

PWR Fuel Engineering Date Reviewed by:

P*F*eI Engineering Manager Date

,eactor*ngineering Supervisor Date Approved, by: ,

PORC Chairman Date Date aae Plasint Revision 0 Pages affected All Reason for Revision- Initial Issue SEQUOYAH - UNIT 2 Page 1 of 12 Revision 0

COLR FOR SEQUOYAH UNIT 2 CYCLE 18 1.0 CORE OPERATING LIMITS REPORT This Core Operating Limits Report (COLR) for Sequoyah Unit 2 Cycle 18 has been prepared in accordance with the requirements of Technical Specification (TS) 6.9.1.14.

The TSs affected by this report are listed below:

TABLE 2.2-1 fl(AI) trip reset function for OTAT Trip (QTNL, QTPL) and rates of trip setpoint decrease per percent Al (QTNS, QTPS)

TABLE 2.2-1 f2(AI) trip reset function for OPAT Trip (QPNL, QPPL) and rates of trip setpoint decrease per percent Al (QPNS, QPPS) 3/4.1.1.3 Moderator Temperature Coefficient (MTC) 314.1.3.5 Shutdown Rod Insertion Limit 3/4.1.3.6 Control Rod Insertion Limits 314.2.1 Axial Flux Difference (AFD) 3/4.2.2 Heat Flux Hot Channel Factor (FQ(X,Y,Z))

3/4.2.3 Nuclear Enthalpy Rise Hot Channel Factor (F&H(XY))

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 the NRC approved methodologies specified in TS 6.9.1.14. The versions of the topical reports which describe the methodologies used for this cycle are listed in Table 1.

The following abbreviations are used in this section:

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 2.1 Moderator Temperature Coefficient - MTC (Specification 314.1.1.3) 2.1.1 The MTC limits are:

The BOLIARO/HZP MTC shall be less positive than 0 Ak/k/°F (BOL limit). With the measured BOL/ARO/HZP MTC more positive than -0.07 x 10"5 Ak/k/°F (as-measured MTC limit), establish control rod withdrawal limits to ensure the MTC remains less positive than 0 Ak/k/°F for all times in core life.

The EOL/AROIRTP MTC shall be less negative than or equal to -4.5 x 10-4 Ak/k/OF.

SEQUOYAH - UNIT 2 Page 2 of 12 Revision 0

COLR FOR SEQUOYAH UNIT 2 CYCLE 18 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 10"4 Ak/k/°F.

2.2 Shutdown Rod Insertion Limit (Specification 3/4.1.3.5) 2.2.1 The shutdown rods shall be withdrawn to a position as defined below:

Cycle Burnup (MWD/MTU) Steps Withdrawn

>0 > 225 to < 231 2.3 Control Rod Insertion Limits (Specification 3/4.1.3.6) 2.3.1 The control rod banks shall be limited in physical insertion as shown in Figure 1.

2.4 Axial Flux Difference - AFD (Specification 314.2.1) 2.4.1 The axial flux difference (AFD) limits (AFDLurn) are provided in Figure 2.

2.5 Heat Flux Hot Channel Factor - EQ(XYZ) (Specification 3/4.2.2)

Fa (X,Y,Z) shall be limited by the following relationships:

FQRTP Fo (X, YZ) < -

• K(Z) for P > 0.5 P

FQRTP Fa (X,Y,Z)ý - -*K(Z) for P < 0.5 0.5 where P = Thermal Power/ Rated Thermal Power 2.5.1 FQRTP = 2.62 2.5.2 K(Z) is provided in Figure 3.

SEQUOYAH - UNIT 2 Page 3 of 12 Revision 0

COLR FOR SEQUOYAH UNIT 2 CYCLE 18 The following parameters are required for core monitoring per the Surveillance Requirements of Specification 3/4.2.2:

2.5.3 NSLOPEAFD = 1.16 where NSLOPEAFO = Negative AFD limit adjustment required to compensate for each 1% that FQ (X,YZ) exceeds BQDES.

2.5.4 PSLOPEAFD = 2.76 where PSLOPEAFD = Positive AFD limit adjustment required to compensate for each 1% that F0 (X,Y,Z) exceeds BQDES.

2.5.5 NSLOPE CA)= 1.44 where NSLOPE f2( = Adjustment to negative OPAT f (Al) limit required to compensate 2

for each 1% that FQ (X,Y,Z) exceeds BCDES.

2.5,6 PSLOPE f2W) = 2.33 where PSLOPE f2(A)= Adjustment to positive OPAT f2(Al) limit required to compensate for each 1% that FQ (X,Y,Z) exceeds BCDES.

2.5.7 BQNOM(X,Y,Z) = Nominal design peaking factor, increased by an allowance for the expected deviation between the nominal design power distribution and the measurement.

2.5.8 BQDES(X,Y,Z) = Maximum allowable design peaking factor which ensures that the FQ (X,Y,Z) limit will be preserved for operation within the LCO limits, including allowances for calculational and measurement uncertainties.

2.5.9 BCDES(X,Y,Z) = Maximum allowable design peaking factor which ensures that the centerline fuel melt limit will be preserved for operation within the LCO limits, including allowances for calculational and measurement uncertainties.

BQNOM(X,Y,Z), BQDES(X,Y,Z), and BCDES(XY,Z) data bases are provided for input to the plant power distribution analysis codes on a cycle specific basis and are determined using the methodology for core limit generation described in the references in Specification 6.9.1.14.

2.5.10 The increase in FQM (X,Y,Z) for compliance with the 4.2.2.2.e Surveillance Requirements is defined as follows:

For cycle bumups 0 to 2796 MWd/mtU, use 2.0%

For cycle burnups >2796 to 4924 MWd/mtU, use 3.47%

For cycle burnups > 4924 to 11699 MWd/mtU, use 2.0%

For cycle burnups >11699 to 11897 MWd/mtU, use 2.09%

For cycle burnups > 11897 MWd/mtU, use 2.0%

SEQUOYAH - UNIT 2 Page 4 of 12 Revision 0

COLR FOR SEQUOYAH UNIT 2 CYCLE 18 2.6 Nuclear Enthalpy Rise Hot Channel Factor - FAH (X.Y) (Specification 3/4.2.3)

FAH (X,Y) shall be limited by the following relationship:

FAH(XY) < MAP(X,Y,Z)/AXlAL(X,Y) 2.6.1 MAP(X,Y,Z) is provided in Table 2.

AXIAL(X,Y) is the axial peak from the normalized axial power shape.

The following parameters are required for core monitoring per the Surveillance Requirements of Specification 3/4.2.3:

FAHRM (X,Y) < BHNOM(XY) where FAHRM (XY) = FHM (X,Y) I MAPM / AXIAL(X,Y)]

FAHM (X,Y) is the measured radial peak at location X,Y.

MAPM is the value of MAP(X,Y,Z) obtained from Table 2 for the measured peak.

2.6.2 BHNOM(X,Y) = Nominal design radial peaking factor, increased by an allowance for the expected deviation between the nominal design power distribution and the measurement.

2.6.3 BHDES(X,Y) = Maximum allowable design radial peaking factor which ensures that the FAH (X,Y) limit will be preserved for operation within the LCO limits, including allowances for calculational and measurement uncertainties.

2.6.4 BRDES(X,Y) = Maximum allowable design radial peaking factor which ensures that the steady state DNBR limit will be preserved for operation within the LCO limits, including allowances for calculational and measurement uncertainties.

BHNOM(X,Y), BHDES(X,Y) and BRDES(X,Y) data bases are provided for input to the plant power.distribution analysis computer codes on a cycle specific basis and are determined using the methodology for core limit generation described in the references in Specification 6.9.1.14.

2.6.5 RRH = 3.34 when 0.8 <P < 1.0 RRH = 1.67 when P_< 0.8 where RRH = Thermal power reduction required to compensate for each 1% that FH(X,Y) exceeds its limit.

P = Thermal Power / Rated Thermal Power SEQUOYAH - UNIT 2 Page 5 of 12 Revision 0

COLR FOR SEQUOYAH UNIT 2 CYCLE 18 2.6.6 TRH = 0.0334when 0.8 < P_< 1.0 TRH = 0.0167 when P < 0.8 where TRH = Reduction in OTAT K1 setpoint required to compensate for each 1%

FAH(X,Y) exceeds its limit.

P= Thermal Power / Rated Thermal Power 2.6.7 All cycle burnups shall use a 2% increase in FHm (X,Y) margin for compliance with the 4.2.3.2.d.1 Surveillance Requirement.

3.0 REACTOR CORE PROTECTIVE LIMITS 3.1 Trip Reset Term [f(AI) I for Overtemperature Delta T-Trip (Specification 2.2.1)

The following parameters are required to specify the power levekdependent fl(AI) trip reset term limits for the Overtemperature Delta-T trip function:

3.1.1 QTNL=-20%

where QTNL = Maximum negative Al setpoint at rated thermal power at which the trip setpoint is not reduced by the axial power distribution.

3.1.2 QTPL = +5%

where QTPL = Maximum positive Al setpoint at rated thermal power at which the trip setpoint is not reduced by the axial power distribution.

3.1.3 QTNS=2.50%

where QTNS = Percent reduction in Overtemperature Delta-T trip setpoint for each percent that the magnitude of Al exceeds its negative limit at rated thermal power (QTNL).

3.1.4 QTPS= 1.40%

where QTPS = Percent reduction in Overtemperature Delta-T trip setpoint for each percent that the magnitude of Al exceeds its positive limit at rated thermal power (QTPL).

SEQUOYAH - UNIT 2 Page 6 of 12 Revision 0

COLR FOR SEQUOYAH UNIT 2 CYCLE 18 3.2 Trip Reset Term r f2(AlI 1 for Overpower Delta-T Trip (Specification 12.21)

The following parameters are required to specify the power level-dependent f2(Al) trip reset term limits for the Overpower Delta-T trip function:

3.2.1 QPNL = -25%

where QPNL = Maximum negative Al setpoint at rated thermal power at which the trip setpoint is not reduced by the axial power distribution.

3.2.2 QPPL = +25%

where QPPL = Maximum positive Al setpoint at rated thermal power at which the trip setpoint is not reduced by the axial power distribution.

3.2.3 QPNS= 1.70%

where QPNS = Percent reduction in Overpower Delta-T trip setpoint for each percent that the magnitude of Al exceeds its negative limit at rated thermal power (QPNL).

3.2.4 QPPS = 1.70%

where QPPS = Percent reduction in Overpower Delta-T trip setpoint for each percent that the magnitude of Al exceeds its positive limit at rated thermal power (QPPL).

SEQUOYAH - UNIT 2 Page 7 of 12 Revision 0

COLR FOR SEQUOYAH UNIT 2 CYCLE 18 Table 1 COLR Methodology Topical Reports

1. BAW-10180-A, Revision 1, "NEMO- Nodal Expansion Method Optimized," March 1993.

(Methodology for Specification 3/4.1.1.3 - Moderator Temperature Coefficient)

2. BAW-10169P-A, Revision 0, "RSG Plant Safety Analysis - B&W Safety Analysis Methodology for Recirculating Steam Generator Plants," October 1989.

(Methodology for Specification 3/4.1.1.3 - Moderator Temperature Coefficient)

3. BAW-10163P-A, Revision 0, "Core Operating Limit Methodology for Westinghouse-Designed PWRs,"

June 1989.

(Methodology for Specifications 2.2.1 - Reactor Trip System Instrumentation Setpoints [fi(AI), f2(AI) limits], 3/4.1.3.5 - Shutdown Rod Insertion Limit, 3/4.1.3.6 - Control Rod Insertion Limits, 3/4.2.1 -

Axial Flux Difference, 3/4.2.2 - Heat Flux Hot Channel Factor, 3/4.2.3 - Nuclear Enthalpy Rise Hot Channel Factor)

4. BAW-10168P-A, Revision 3, "RSG LOCA - BWNT Loss of Coolant Accident Evaluation Model for Recirculating Steam Generator Plants," December 1996.

(Methodology for Specification 3/4.2.2 - Heat Flux Hot Channel Factor)

5. BAW-10227P-A, Revision 1, "Evaluation of Advanced Cladding and Structural Material (M5) in PWR Reactor Fuel," June 2003.

(Methodology for Specification 3/4.2.2 - Heat Flux Hot Channel Factor)

6. BAW-10186P-A, Revision 2, "Extended Burnup Evaluation," June 2003.

(Methodology for Specification 3/4.2.2 - Heat Flux Hot Channel Factor)

7. EMF-2103P-A, "Realistic Large Break LOCA Methodology for Pressurized Water Reactors",

April 2003.

(Methodology for Specification 3/4.2.2-Heat Flux Hot Channel Factor)

SEQUOYAH - UNIT 2 Page 8 of 12 Revision 0

COLR FOR SEQUOYAH UNIT 2 CYCLE 18 Table 2 Maximum Allowable Peaking Limits MAP(X,Y,Z)

AXIAL(X,Y) ELEVATION (ft) MAP (X,Y,Z) AXIAL (X,Y) ELEVATION (ft) MAP(X,Y,Z) 2 1.9796 2 2.8084 4 1.9750 4 2.9772 1.1 6 1.9675 1.9 6 2.9986 8 1.9561 8 2.8424 10 1.9346 10 2.6948 2 2.1787 2 2.5301 4 2.1683 4 2.6821 1.2 6 2.1890 >1.9 6 2.7014 8 2.1626 8 2.5607 10 2.0894 10 2.4278 2 2.4200 2 2.6742 4 2.4024 4 3.3050 1.3 6 2.4119 2.2 6 3.1569 8 2.3100 8 3.0147 10 2.1923 10 2.7071 2 2.6650 2 2.6810 4 2.6238 4 3.5687 1.4 6 2.5696 2.6 6 3.5402 8 2.4224 8 3.3006 10 2.2895 10 2.9649 2 2.7164 2 2.9366 4 2.7476 4 3.7887 1.5 6 2.6782 3.0 6 4.1090 8 2.5262 8 3.6762 10 2.3832 10 3.3366 2 2.7673 2 2.9665 4 2.9138 4 4.0948 1.7 6 2.8590 3.5 6 4.1053 8 2.7018 8 3.7168 10 2.5502 10 3.4708 SEQUOYAH - UNIT 2 Page 9 of 12 Revision 0

COLR FOR SEQUOYAH UNIT 2 CYCLE 18 (0.606,231) 220 200 -

-" ] - 1 - , ,-Ts 21USX ---___

_ _

180oT o 160 o 140 IL 120 -

V) (0,110)

-* 100 _ _ - --

80 tBANK D x*0 60 --

1_ _ _

_T_

__

-

_

__

40 20 (0.09,0 0

0 0.2 0.4 0.6 0.8 (Fully Inserted)

Fraction of Rated Thermal Power FIGURE 1 Rod Bank Insertion Limits Versus Thermal Power, Four Loop Operation

• Fully withdrawn region shall be the condition where shutdown and control banks are at a position within the interval of >225 and <231 steps withdrawn, inclusive.

Fully withdrawn shall be the position as defined below, Cycle Burnup (MWd/mtU) Steps Withdrawn

>0 >225 to <231 This figure is valid for operation at a rated thermal power of 3455 MWt when the LEFM is in operation.

Ifthe LEFM becomes inoperable, then prior to the next NIS calibration, the maximum allowable power level must be reduced by 1.3% in power, and the rod insertion limit lines must be increased by 3 steps withdrawn until the LEFM is returned to operation.

SEQUOYAH - UNIT 2 Page 10 of 12 Revision 0

COLR FOR SEQUOYAH UNIT 2 CYCLE 18 120 110 - -I- - -

Uacceptp ble Unac(

90 n \- i-e Acceptable so _**

• pra-o _ _* -

870 ..... to 60 5-4-

70

"*I - I 30 - --

40 2O I __ (2, 20

_OI _ -

10 7-F -I-_

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

FIGURE 2 Axial Flux Difference Limits As A Function of Thermal Power For Burnup Range 0 EFPD to EOL This figure is valid for operation at a rated thermal power of 3455 MWt when the LEFM is in operation.

If the LEFM becomes inoperable, then prior to the next NIS calibration, the maximum allowable power level must be reduced by 1.3% in power, and the AFD limit lines must be made more restrictive by 1%

in AFD until the LEFM is returned to operation.

SEQUOYAH - UNIT 2 Page 11 of 12 Revision 0

COLR FOR SEQUOYAH UNIT 2 CYCLE 18 1.2 2i 1.0 III I I I

I

~ r I

I I ~ I 0.8 0.6 Elevation Klz) 0.000 1 .0000 0.4 ---

-- -- - -- 6.285 1.0000 '- -- - -- - - - - -

7.995 1.0000 9.705 1.0000 12.000 1.0000 r------------ ----

• -.-.-----------.- -

0.2 0.0 0 2 4 6 8 10 12 Core Height (Feet)

FIGURE 3 K(Z) - Normalized FQ(XY,Z) as a Function of Core Height SEQUOYAH - UNIT 2 Page 12 of 12 Revision 0