ML20115G812

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Proposed Tech Specs Re Moveable Incore Detector Thimble Reduction
ML20115G812
Person / Time
Site: Prairie Island  Xcel Energy icon.png
Issue date: 07/15/1996
From:
NORTHERN STATES POWER CO.
To:
Shared Package
ML19311C094 List:
References
NUDOCS 9607220076
Download: ML20115G812 (12)
v • d • e


Text

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+ .

i l

l Exhibit B  !

Prairie Island Nuclear Generating Plant j License Amendment Request Dated July 15, 1996 h i

Proposed Changes Marked Up On Existing Technical Specification Pages ,

i i

Exhibit B consists of existing Technical Specification pages with the proposed -

changes highlighted on those pages. The pages affected by this License l Amendment Request are listed below: ';

i TS.3.10-1  !

TS.3.10-2 .

.TS.3.10-3 TS.3.11-1 B.3.11-1 '

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l I o .

l I

s e i i

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9607220076 960715 PDR ADOCK 05000282 p PDR:

TS.3.10-1 RE" 111 S/10/9^

3.10 CONTROL ROD AND POWER DISTRIBUTION LIMITS Applicability Applies to the limits on core fission power distribution and to the limits on control rod operations.

Obiective To assure 1) core suberiticality after reactor trip, 2) acceptable core power distributions during POWER OPERATION, and 3) limited potential reactivity insertions caused by hypothetical control rod ejection.

Specification A. Shutdown Marcin

1. Reactor Coolant System Averane Temperature > 200'F The SHUTDOWN MARGIN shall be greater than or equal to the applicable value shown in Figure TS.3.10-1 when in HOT SHUTDOWN and INTERMEDIATE SHUTDOWN.
2. Reactor Coolant System Averane Temperature s 200*F The SHUTDOWN MARGIN shall be greater than or equal to 1%Ak/k when in COLD SHUTDOWN.
3. With the SHUTDOWN MARGIN less than the applicable limit specified in 3.10.A.1 or 3.10.A.2 above, within 15 minutes initiate boration to restore SHUTDOWN MARGIN to within the applicable limit.

B. Power Distribution Limits 1.Atalltimes,exceptduringlowpowerPHYSICSTESTING,measuredhotchannel factors, Fn8 and F a, as defined below and in the bases, shall meet the following limits:

RTP F8 n x 1.03 x 1.051 s (Fn / P) x K(Z)

RTP 8

Fa x 1.04 M $ Fa x [1+ PFDH(1-P)]

where the following definitions apply:

RTP

- Fn is the Fo limit at RATED THERMAL POWER specified in the CORE OPERATING LIMITS REPORT.

RTP

- Fu is the Fu limit at RATED THERMAL POWER specified in the CORE OPERATING LIMITS REPORT.

8

- PFDH is the Power Factor Multiplier for F a specified in the CORE OPERATING LIMITS REPORT.

l

- K(Z) is a normalized function that limits F n (z) axially as specified in the  !

CORE OPERATING LIMITS REPORT. l l

[* For' Unit1,'" Cycle'18; when' the numbet of available' moveabis detector thimbles is

~

t greater than or equal to 50% and less than 75% of the total, the 54 measurement" f uncertainty'shall be increased to j$t f,(3-T/9)(3%)),[vhere T, is',the number of, ^

g,available , thimbles.

1

    • iFoMUni't@MCyc1M1;8Mwhesi!thsZnumbeWof#va11ableisofsabl4?detEEtorE#himbles!!ij

% [greaterRthan M rtequal(toiS0tjandilessythan275t?ofithe1? totals thsj4M messdrement, f tuncertainty@halllbslinerease.dMoy[3%MQtT/9)J2%))j#hereiT?isithsinsmberfof

!$dayai} @ ehth}mb}e,g j l

l 1

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= l TS.3.10-2 1 D. T*17 111 .O,/1. A,/

- O, A i

3.10.B.l. - Z is the core height location.

- P is the fraction of RATED THERMAL POWER at which the core is i operating. In the r"n limit determination when P 50.50,  ;

set P - 0.50, I

8

- Fn or F"a is defined as the measured Fn or Fu respectively, with ,

the smallest margin or greatest excess of limit.  ;

i

- 1.03 is the8 engineering hot channel factor, F Eg, applied to the i measured F n to account for manufacturing tolerance.

- 1.053 is applied to the measured F Nn to account for measurement ,

uncertainty. l 1.04pf is applied to the measured F"a to account for measurement uncertainty. ,

l

2. Hot channel factors, Fn8 and F8g , shall be measured and the target flux difference determined, at equilibrium conditions according to l the following conditions, whichever occurs first:  !

i (a) At least once per 31 effective full-power days in conjunction i with the target flux difference determination, or ]

(b) Upon reaching equilibrium conditions after exceeding the reactor power at which target flux difference was last determined, by 10% or more of RATED THERMAL POWER.

F8 n (equil) shall meet the following limit for the middle axial 80%

of the core: l

. RTP I F"n (equil) x V(Z) x 1.03 x 1.053 s (Fn / P) x K(Z) j 1

where V(Z) is specified in the CORE OPERATING LIMITS '

REPORT and other terms are defined in 3.10.B.1 above.

l

3. (a) If either measured hot channel factor exceeds its limit l specified in 3.10.B.1, reduce reactor power and the high neutron flux trip set-point by 1% for each percent that the measured NFn or by the factor specified in the CORE l OPERATING LIMITS REPORT for each percent that the measured F"a exceeds the 3.10.B.1 limit. Then follow 3.10.B.3(c).

(b) If the measured FN g (equil) exceeds the 3.10.B.2 limits but not the 3.10.B.1 limit, take one of the following j actions: '

1. Within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> place the reactor in an equilibrium configuration for which Specification 3.10.B.2 is satisfied, or ,

l 2.

Reduce reactor power and the high neutron flux trip setpoint by 1% for each percent that the measured  ;

F8 n (equil) x 1.03 x 1.05*] x V(Z) exceeds the limit.  !

i ** For Unit 1l Cycle"18 7'when^ the number *Lf'available" moveable detector "

I t thimbles is greater than or' equal to 50% and less than 754 of the

{ total, the 54 measurement uncertainty shall be" increased to '

t [541(3-T[9),(3%)j vhere T is the number of;available, thimblis'^"

    • For Unit ^1', Cycle' 1B l'~when' the" number ~of 'available 'mov'eable"deteetor

! ' thimbles'is greater than or equal to 50% and less than 75% of the' i totsi, the 44' measurement uncertainty shall be increased to' b_I441 s(.3-T/9)Qt)J where,,T is the number,of 'available thimblesE

i TS.3.10-3 j RE" 92 2/12/90 3.10 B.3. (c) If subsequent in-core mapping cannot, within a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period, i demonstrate that the hot channel factors are met, the reactor  ;

shall be brought to a HOT SHUTDOWN condition with return to l power authorized up to 50% of RATED THERMAL POWER for the

7 purpose of PHYSICS TESTING. Identify and correct the cause j

. of the out of limit condition prior to increasing THERMAL POWER j above 50% of RATED THERMAL POWER. THERMAL POWER may then be  :

8 increased provided F*o or F$m is demonstrated through in-core  ;

mapping to be within its limits. ,

i (d) If two successive measurements indicate an increase in the i peak rod power F53 with exposure, either of the following j actions shall be taken:

1. F*o (equil) shall be multiplied by 1.02 x V(Z) x 1.03 x 1.05&gforcomparisontothelimitspecifiedin3.10.B.2,or
2. F*o (equil) shall be measured at least once per seven effective full power days until two successive maps indicate that the peak pin power, Pka, is not increasing.
4. Except during PHYSICS TESTS, and except as provided by specifica-tions 5 through 8 below, the indicated axial flux difference for at least three operable excore channels shall be maintained within the target band about the target flux difference. The target. band is specified in the CORE OPERATING LIMITS REPORT.

l

5. Above 90 percent of RATED THERMAL POWER:

l If the indicated axial flux difference of two OPERABLE excore channels deviates from the target band, within 15 minutes either i eliminate such deviation, or reduce THERMAL POWER to less than 90 percent of RATED THERMAL POWER.  !

6. Between 50 and 90 percent of RATEL THERMAL POWER:
a. The indicated axial flux difference may deviate from the target band for a maximum of one* hour (cumulative) in any 24-hour period provided that the difference between the indicated axial flux difference about the target flux difference does not exceed the envelope specified in the CORE OPERATING LIMITS REPORT.
b. If 6.a is violated for two OPERABLE excore channels then the THERMAL POWER shall be reduced to less than 50% of RATED THERMAL POWER and the high neutron flux setpoint reduced to less than 55% of RATED THERMAL POWER.
  • May be extended to 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> during incore/excore calibration.

f* **~ For' Unit ^ 1'," Cycle :18;';when'the~numbiir of'availablf nioviable" detector

) thimbles is greater than or, equal to 50% and less chan 75t'of the ~ '

h tota 1L the 50 measurement uncertainty shall be increased to ~' '

k_.s(54;f;(3-7/9)(3tH where T is;the number of ,availableithimblesg m

1

6 TS.3.11-1 PS1 91 10/27/89 3.11 CORE SURVEILLANCE INSTRUMENTATION Acolicability Applies to the OPERABILITY of the moveable detector instrumentation system and the core thermocouple instrumentation system.

Obiective To specify OPERABILITY requirements for the moveable detector and  !

core thermocouple systems. .

t Soecification~

f A. The moveable detector system shall be OPERABLE following each refueling i so that the power distribution can be confirmed. If the moveable  :

detector system is degraded to the extent that less than 75% of the  !

detector thimbles are'available, the measurement error allowance due to ,

incomplete mapping shall be substantiated by the licensee.  !

B. A minimum of 2 moveable detector thimbles per quadrantg, and  :'

sufficient detectors, drives,'and readout equipment to map these thimbles, shall'be operable during recalibration of the excore axial l offset detection system per Specification 4.1. If this OPERABILITY:  !

for recalibration of excore nuclear instruments when required by.-  !

Specification 4.1 cannot be achieved, power"shall be limited to 904 l of RATED THERMAL POWER until recalibration is completed in accor-  ;

dance with this specification.  ;

}

r C. A minimum of 4 thermocouples or 2 moveable detectors per quadrant j

shall be operable'for readout if.the reactor is operated above 854'of 4

-RATED THER. MAL POWER with one excore nuclear power channel inoperable (see. Specification 3.10.C.4). J D. The provisions of specification 3.0.C are not applicable.

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B.3.11-1 P9' 91 10/27/99 j 3.11 CORE SURVEILLANCE INSTRUMENTATION Bases The moveable detector system is used to measure the core fission power density distribution. A power map made with this system following each fuel loading will confirm the proper fuel arrangement within the core. The moveable detector system is designed with substantial redundancy so that part of the system could be out of service without reducing the value of a power map. If the system is severely degraded, large measurement uncertainty factors must be applied. The uncertainty factors would necessarily depend on the operable configuration.

Two detector thimbles per quadrant are sufficient to provide data for the normalization of the excore detector system's axial power offset feature.

For' Unit *1, Cycle' 18',' when th~e" number of availableTaoveable'~ detector thimbles is greater than' or equal,to 50% and less than 75% of the total, the' requirements are, modified to require a minimum'!-( two, thimbles'available per quadrant, where qutdrist' includes t ':b borizontalJvertical q'uadrants and diagonallylbo mded ' quadrants'< (eight individual quadrants in total). This requires /Q' rises from the use

'f o random thimble deletion' events'as the basis 1 e the Westin6housa analysis. ,As a result of random failures, distribution of remaining

' thimbles would be relatively uniform, while systematic failure ~could

'esult in large areas of the core being uninstrumented. In order to r

a' pply the error correction' develop'ed in the Westinghouse analysis, and I to establish the bounds of applicability of the peaking factor uncertainties, coverage,is, required in each of the eight, quadrants defined,above.3 The core thermocouples provide an independent means of measuring the balance of power among the core quadrants. If one excore power channel is out of service, it is prudent to have available an independent means of determining the quadrant power balance.

The moveable detector system and the thermocouple system are not integral parts of the reactor protection system. These systems are, rather, surveillance systems which may be required in the event of an abnormal occurrence such as a power tilt or a control rod misalignment. Since such occurrences cannot be predicted a priori, it is prudent to have the surveillance systems in an OPERABLE state.

1 I

I Exhibit C i Prairie Island Nuclear Generating Plant l

License Amendment Request Dated July 15, 1996 Revised Technical Specification Pages Exhibit C consists of revised pages for the Prairie Island Nuclear Generating Plant Technical Specifications with the proposed changes incorporated. The revised pages are listed below:

TS 3.10-1 TS 3.10-2 TS.3.10-3 ,

TS.3.11-1  !

B.3.11-1 l

1 l

I 1

l l

i

4 TS.3.10-1 3.10 CONTROL ROD AND POWER DISTRIBUTION LIMITS Applicability Applies to the limits on core fission power distribution and to the limits on control rod operations.

Obiective a

To assure 1) core suberiticality after reactor trip, 2) acceptable core power 1 distributions during POWER OPERATION, and 3) limited potential reactivity insertions caused by hypothetical cont :o1 rod ejection.

f Specification I A. Shutdown Marzin

1. Reactor Coolant System Averare Temperature > 200*F The SHUTDOWN MARGIN shall be greater than or equal to the applicable value  !

l shown in Figure TS.3.10-1 when in HOT SHUTDOWN and INTERMEDIATE SHUTDOWN. '

2. Reactor Coolant System Averare Temperature s 200*F The SHUTDOWN MARGIN shall be greater than or equal to 1%Ak/k when in COLD SHUTDOWN.
3. With the SHUTDOWN MARGIN less than the applicable limit specified in 3.10.A.1 or 3.10.A.2 above, within 15 minutes initiate boration to restore SHUTDOWN ,

MARGIN to within the applicable limit. l B. Power Distribution Limits l 2

l 1.Atalltimes,exceptduringlowpowerPHYSICSTESTING,measuredhotchannel i factors, F"q and F gg, as defined below and in the bases, shall meet the following limits:

RTP F"q x 1.03 x 1.05* s (Fg / P) x K(Z)

RTP FN ;m x 1.04** s Fig x [l+ PFDH(1-P)]

where the following definitions apply:

RTP

-F n is the Fg limit at RATED THERMAL POWER specified in the CORE OPERATING LIMITS REPORT.

RTP

- Fin is the Fig limit at RATED THERMAL POWER specified in the CORE OPERATING LIMITS REPORT.

- PFDH is the Power Factor Multiplier for F g specified N

f in the CORE OPERATING LIMITS REPORT.

- K(Z) is a normalized function that limits Fn(z) axially as specified in the CORE OPERATING LIMITS REPORT.

  • For Unit 1, Cycle 18, when the number of available moveable detector thimbles is greater than or equal to 50% and less than 75% of the total, the 5% measurement uncertainty shall be increased to [5% + (3-T/9)(3%)] where T is the number of available thimbles.
    • For Unit 1, Cycle 18, when the number of available moveable detector thimbles is greater than or equal to 50% and less than 75% of the total, the 4% measurement uncertainty shall be increased to [4% + (3-T/9)(2%)] where T is the number of available thimbles.

TS.3.10-2 e

3.10.B.l. - Z is the core height location.

P is the fraction of RATED THERMAL POWER at which the core is operating. In the Fun limit determination when P 50.50, set P - 0.50.

8 Fn or F8g is defined as the measured Fn or Fu respectively, with ,

the smallest margin or greatest excess of limit. i

- 1.03 is the engineering hot channel factor, FE, g applied to the measured F"o to account for manufacturing tolerance.

1.05* is applied to the measured F n8 to account for measurement l I uncertainty.

1.04** is applied to the measured F N to account for measurement l uncertainty.

2. Hot channel factors, F 8n and F"a , shall be measured and the target flux difference determined, at equilibrium conditions according to the following conditions, whichever occurs first:

(a) At least once per 31 effective full-power days in conjunction with the target flux difference determination, or (b) Upon reaching equilibrium conditions after exceeding the reactor power at which target flux difference was last determined, by 10% or more of RATED THERMAL POWER.

FN n (equil) shall meet the following limit for the middle axial 80%

of the core:

RTP l FN n (equil) x V(Z) x 1.03 x 1.05* s (Fn / P) x K(Z) I where V(Z) is specified in the CORE OPERATING LIMITS REPORT and other terms are defined in 3.10.B.1 above.

3. (a) If either measured hot channel factor exceeds its limit specified in 3.10.B.1, reduce reactor power and the high neutron flux trip set-point by 1% for each percent that the measured F"o or by the factor specified in the CORE OPERATING LIMITS REPORT for each percent that the measured F"a exceeds the 3.10.B.1 limit. Then follow 3.10.B.3(c).

(b) If the measured Fun (equil) exceeds the 3.10.B.2 limits i but not the 3.10.B.1 limit, take one of the following actions:

1. Within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> place the reactor in an equilibrium configuration for which Specification 3.10.B.2 is satisfied, or
2. Reduce reactor power and the high neutron flux trip setpoint by 1% for each percent that the measured F"o (equil) x 1.03 x 1.05* x V(Z) exceeds the limit.
  • For Unit 1, Cycle 18, when the number of available moveable detector l thimbles is greater than or equal to 50% and less than 75% of the total, the 5% measurement uncertainty shall be increased to

[5% + (3-T/9)(3%)] where T is the number of available thimbles.

    • For Unit 1, Cycle 18, when the number of available moveable detector thimbles is greater than or equal to 50% and less than 75% of the j total, the 4% measurement uncertainty shall be increased to (4% + (3-T/9)(2%)] where T is the number of available thimbles.

I

\

TS.3.10-3 3.10.B 3. (c) If subsequent in-core mapping cannot, within a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period, demonstrate that the hot channel factors are met, the reactor shall be brought to a HOT SHUTDOWN condition with return to power authorized up to 50% of RATED THERMAL POWER for the purpose of PHYSICS TESTING. Identify and correct the cause of the out of limit condition prior to increasing THERMAL POWER above 50% of RATED THERMAL POWER. THERMAL POWER may then be increased provided F"o or F"a is demonstrated through in-core mapping to be within its limits.

(d) If two successive measurements indicate an increase in the peak rod power F%a with exposure, either of the following actions shall be taken:

1. F"o (equil) shall be multiplied by 1.02 x V(Z) x 1.03 x 1.05** for comparison to the limit r,pecified in 3.10.B.2, or l 8
2. F g (equil) shall be measured at least once per seven effective full power days until two successive maps indicate that the peak pin power, F53, is not increasing.
4. Except during PHYSICS TESTS, and except as provided by specifica-tions 5 through 8 below, the indicated axial flux difference for at least three operable excore channels shall be maintained within the target band about the target flux difference. The target band is specified in the CORE OPERATING LIMITS FIPORT.
5. Above 90 percent of RATED THERMAL POWER:

If the indicated axial flux difference of two OPERABLE excore channels deviates from the target band, within 15 minutes either eliminate such deviation, or reduce THERMAL POWER to less than 90 percent of RATED THERMAL POWER.

6. Between 50 and 90 percent of RATED THERMAL POWER:
a. The indicated axial flux difference may deviate from the target band for a maximum of one* hour (cumulative) in any 24-hour period provided that the difference between the indicated axial flux difference about the target flux difference does not exceed the envelope specified in the CORE OPERATING LIMITS REPORT.
b. If 6.a is violated for two OPERABLE excore channels then the THERMAL POWER shall be reduced to less than 50% of RATED THERMAL POWER and the high neutron flux setpoint reduced to less than 55% of RATED THERMAL POWER.

4

  • May be extended to 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> during incore/excore calibration.
    • For Unit 1, Cycle 18, when the number of available moveable detector thimbles is greater than or equal to 50% and less than 75% of the total, the 5% measurement uncertainty shall be increased to

[5% + (3-T/9)(3%)) where T is the number of available thimbles.

TS.3.ll-1 3.11 CORE SURVEILLANCE INSTRUMENTATION Applicability Applies to the OPERABILITY of the moveable detector instrumentation system and the core thermocouple instrumentation system.

i Obiective j To specify OPERABILITY requirements for the moveable detector and ]

core thermocouple systems.

l Specification '

A. The moveable detector system shall be OPERABLE following each refueling so that the power distribution can be confirmed. If the moveable detector system is degraded to the extent that less than 75% of the detector thimbles are available, the measurement error allowance due to incomplete mapping shall be substantiated by the licensee.

B. A minimum of 2 moveable detector thimbles per quadrant *, and sufficient detectors, drives, and readout equipment to map these j thimbles, shall be operable during recalibration of the excore axial  !

offset detection system per Specification 4.1. If this OPERABILITY for recalibration of excore nuclear instruments when required by Specification 4.1 cannot be achieved, power shall be limited to 90%

of RATED THERMAL POWER until recalibration is completed in accor-  ;

dance with this specification. I C. A minimum of 4 thermocouples or 2 moveable detectors per quadrant  ;

i shall be operable for readout if the reactor is operated above 85% of RATED THERMAL POWER with one excore nuclear power channel inoperable (see Specification 3.10.C.4).

D. The provisions of specification 3.0.C are not applicable.

  • For Unit 1, Cycle 18, when the number of available moveable detector thimbles is greater than or equal to 50% and less than 75% of the total, there should be a minimum of two thimbles available per quadrant, where quadrant includes both horizontal-vertical quadrants and diagonally-bounded quadrants (eight individual quadrants in total).

B.3.11-1 REV 91 10/27/89 3.11 CORE SURVEILLANCE INSTRUMENTATION Bases The moveable detector system is used to measure the core fission power density distribution. A power map made with this system following each fuel loading will confirm the proper fuel arrangement within the core. The moveable detector system is designed with substantial redundancy so that part of the system could be out of service without i reducing the value of a power map. If the system is severely  !

degraded, large measurement uncertainty factors must be applied. The j uncertainty factors would necessarily depend on the operable '

configuration, j 1

Two detectc; thimbles per quadrant are sufficient to provide data for the normalization of the excore detector system's axial power offset feature.

For Unit 1, Cycle 18, when the number of available moveable detector thimbles is greater than or equal to 50% and less than 75% of the total, the requirements are modified to require a minimum of two thimbles available per quadrant, where quadrant includes both horizontal-vertical quadrants and diagonally-bounded quadrants (eight individual quadrants in total). This requirement arises from the use of random thimble deletion events as the basis for the Westinghouse analysis. As a result of random failures, distribution of remaining thimbles would be relatively uniform, while systematic failure could result in large areas of the core being uninstrumented. In order to  !

apply the error correction developed in the Westinghouse analysis, and to establish the bounds of applicability of the peaking factor uncertainties, coverage is required in each of the eight quadrants defined above.

The core thermocouples provide an independent means of measuring the balance of power among the core quadrants. If one excore power channel is out of service, it is prudent to have available an independent means of determining the quadrant power balance.

The moveable detector system and the thermocouple system are not integral parts of the reactor protection system. These systems are, rather, surveillance systems which may be required in the event of an abnormal occurrence such as a power tilt or a control rod misalignment. Since such occurrences cannot be predicted a priori, it is prudent to have the surveillance systems in an OPERABLE state.

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