ML20032D680

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Proposed Tech Spec Section 3/4.2 on Power Distribution Limits,Allowing Continued Full Power Operation at Steam Generator Tube Plugging Levels Up to 7%,per LOCA-ECCS Reanalysis
ML20032D680
Person / Time
Site: North Anna  Dominion icon.png
Issue date: 11/12/1981
From:
VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML20032D546 List:
References
NUDOCS 8111170383
Download: ML20032D680 (22)
v • d • e


Text

{{#Wiki_filter:- ~ Proposed Technical Specification Changes 8111170383 811112 PDR ADOCK 05000338 i P PDR

. ~. ( t ) i Unit 1 Technical Specifications s k I i k

_5/4.2 POWER DISTRIBUTION LIMITS AXIAL FLUX DIFFERENCE (AFD) LIMITING CONDITION FOR OPERATION 3.2.1' The indicated AXIAL FLUX DIFFERENCd (AFD) shall be maintained within a 15% target band (flux difference units) about the target' flux difference. APPLICABILITY: MODE 1 ABOVE 50% RATED THERMAL POWER

  • ACTION:

a.- With the indicated AXIAL FLUX DIFFERENCE outside of'the tS% 4 target band about the targst flux difference and with THERMAL i POWER: 1. Above 84% of RATED THERMAL POWER, within 15 minutes: a) Either restore the indicated AFD to within the target band limits, or b) Reduce THERMAL POWER to less than 84% of RATED l THERMAL POWER. 2. Between 50% and 84% of RATED THERMAL POWER: J l a) POWER OPERATION may continue provided:

1) The indicated AFD has not been outside cf the 25% target band for more than 1 hour penalty deviation cumulative during the previous 24-hours, and t
2) The indicated AFD is within the limits shown on I.

Figure 3.2-1. Otherwise, reduce THERMAL POWER l to less than 50% of RATED THERMAL POWER within 30 minutes and reduce the Power Range Neutron Flux-High Trip Setpoints to less than or equal to 55% l of RATED THERMAL POWER within the next 4 hours. ] b) Surveillance testing of the Po 'tr Range Neutron Flux Channels may be performed pursuant en "pecification i 4.3.1.1.1 provided the indicated AFD is maintained within the limits of Figure 3.2-1. A total of 16 hour i of operation may be accumulated with the AFD outside { of the target band during this testing without penalty i deviation. l. (

  • See Special Test Exception 3.10.2.

I NORTH ANNA - UNIT 1 3/4 2-1 1 i i ~ -. .-.---._-,...?

i POWER DISTRIBUTION LIMITS LIMITING CONDITION FOR OPERATION (Continued) b. THERMAL POWER shall not be increased above 84% of RATED THERMAL POWER unless the indicated AFD is within the 25% target band and ACTION 2.a.1, above has been satisfied. c. THERMAL POWER shall not bt increased above 50% of RATED THERMAL POWER unless the indicated AFD has not been outside of the 25% target band for more than I hour penalty deviation cumulative during the previous 24 hours. SURVEILLANCE REQUIREMEN"S 4.2.1.1 The indicated AXIAL FLUX DIFFERENCE shall be determined to be within its limits during POWER OPERATION above 15% of RATED THERMAL POWER by: 0 Monitoring the indicated AFD for each OPERABLE excore channel: a. 1. At least once per 7 days when the AFD Monitor Alam is OPERABLE, and 2. At least once per hour for the first 24 hours after restoring the AFD Monitor Ala m to OPERABLE status, b. Monitoring and logging the indicated AXIAL FLUX DIFFERENCE for each OPERABLE excore channel at least once per hour for the first 24 hours and at least once per 30 minutes thereafter, when the AXIAL FLUX DIFFERENCE Monitor Alarm is inoperable, The logged values of the indicated AXIAL FLUX DIFFERENCE shall be assumed to exist during the interval preceding each logging. 4.2.1.2 The indicated AFD shall be considered outside of its 25% target band when at least 2 OPERABLE excore channels are indicating the AFD to be outside the target band. Penalty deviation outside of the tS% target band shall be accumulated on a time basis of: One minute penalty deviation for each one minute of POWER OPERATION a. outside of the target band at THERMAL POWER levels equal to or above 50% of RATED THERMAL POWER, and b. One-half minute penalty deviation for each one minute of POWER OPERATION outside of the target band at THERMAL POWER levels between 15% and 50% of RATED THERMAL POWER. NORTH ANNA - UNIT 1 3/4 2-2 si

l i i ._h I L_ ' -y 110 _I 'I I i i I i I I j i i i i 'R o i i i l I ~E 100 l 'm I 5 ? t I 'O W i i j l._. j i i t !(-10'.0. M _ 00LOM) I I t 80 i i ! -/ N i 1 -i/ i .{ \\ j l i UNACCEPTABLE-i ! ;' UNACCEPTABLE - i - 03E?lTIO!2 ' OPEP A. TION 60 -i d / ~!- -k i I /i .! \\ ~ ! -j l i/ ACCEPTABLE OPERATION.\\ l ~-(d7.0;40) (-N.0;50) I I .I I i i 40 8 i -I i i l t i l 1 -t - i -i i __; 20 i i I i l 1 I i i t I l 4 l 'l i I i i 0 I I I I _-5 0..._ _.40._-30 -io -f0 0 10 70 ___30_4d 50____ p FLUX DIFFERENCE (41) % FIGURE 3.2-1 AXIAL FLUX DIFFERENCE LIMITS AS A FUNCTION OF RATED THERMAL POWER NORTH ANNA - UNIT 1 3/4 2-4

POWER DISTRIBUTION LIMITS HEAT FLUX HOT CHANNEL FACTOR-F (Z) LIMITING CONDITION FOR OPERATION 3.2.2 F (Z) shall be limited by the following relationships: q I F (Z) 1 [2.14] [K(Z)]for P > 0.5 l q P i F 9 ; [4.28] [K(Z)]for P 10.5 9 waere P = THERMAL POWER RATED THERMAL POWER and K(Z) is the function obtained from Figure 3.2-2 for a given core height location. APPLICABILITY: MODE 1. ACTIOg With F (Z) exceeding its limit: q a. Comply with either of the following ACTIONS: 1. Reduce THERMAL POWER at least t% for each 1% F (Z) exceeds the 9 limit within 15 minutes and sbn11arly reduce the Power Range Neutron Flux-High Trip Setpoints within the next 4 hours; POWER OPERATION may proceed for up to a total of 72 hours; subsequent POWER OPERATION may proceed provided the Overpower aT. Trip Setpoints Psve been reduced at least 1% for each 1% F (Z) q exceeds the limit. The Overpower AT Trip Setpoint reduction shall'be performed with the reactor ir. at least HOT STANDBY. 2. Reduce THERMAL POWER as necessary to meet the limits of Specificatior 3.2.6 using the APDMS with the latest incore map and updated R. b. Identify and correct the cause of the ouc of limit condition prior to increasing THERMAL POWER above the reduced limit required by a, above; THERMAL POWER may then be increased provided F (Z) is demonstrated througb incore mapping to be within its limit. NORTH ANNA - UNIT 1 3/4 2-5 - + v ri +/-e a-ami3y-y---- ,vr-we-aAv-y-- eu------.- e- ,,---ye-n--, --e m -n-- --v~- g- +- &w

i ~ -i + ( 6-0,-t -D ) ~ t ~~-(10 9 0.93) -- i i 0.8 i i \\. ~ D f 0.6 i -E N 3 ~j i- ) 6 ~ ~"tl2-C,0 46F s2 I. ?!? 0.4 E t -y o.2 i i-- t i -I t 1 I t t l o l 2 4 6 8 10 12 CORE HEIGHT (FT) Figure 3.2-2 K(Z) - Normalized F (Z) as a Function of Core Height NORTH ANNA - UNIT 1 3/4 2-8

1 s POWER DISTRIBUTION LIMITS AXIAL POWER DISTRIBUTION i LIMITING CONDITION FOR OPERATION 3.2.6 The axial power distribution shall be limited by the follewing relationship: [F)(Z)]g = (R )(P )(1.03)(1 A ej) (1.07) 1 Where: F (Z)'is the normalized axial power distribution from thimble a. j at core elevation Z. i b. P is the fraction of RATED THERMAL POWER. c. K(Z) is the function obtained from Figure 3.2-2 for a given core height location. d. R, for thimble j, is determined from at least n=6 incore flux mapa covering the full configuration of permissible red patterns above 94% of RATED THERMAL POWER in accordance with: n R = j 13 i=1 Where: y,,, 01 ij [Ff(Z)] Max and[F (Z)]h is the maximum value of the norm ized axial distribution at elevation Z frog thimble j in map i which had a measured peaking factor without uncertainties eas or densification allowance of F NORTH ANNA - UNIT 1 3,4 2-16

POWER DISTRIBUTION LIMITS i LIMITING CONDITION FOR OPERATION (Continued) l og is the standard deviation asr ociated with thimble j, expressed e. ao a fraction or percentage of R), and is derived from n flux maps } from the relationship below, or 0.02, -(2%) whichever is greater. n)] [nl1 i=1(5 - Rij)} _e j j ij r f. The factor 1.07 is comprised of 1.02 and 1.05 to account for the axial power distribution instrumentation accuracy and the measure-ment uncertainty associated with ?q using the movable detector system, respectively. g. The factor 1.03 is the engineering unwertainty frctor. APPLICABIIITY : MODE 1 ABOVE 94% OF RATED THERMAL POWER. t' ACTION: a. With a F (Z) factor exceeding [F)(Z)]g by less than or equal to 4 l percent, reduce THERMAL POWER one percent tar every percent by which the F (Z) factor exceeds its limit within 15 minutes and within the next two hours either reduce the F)(Z) factor to within its limit or reduce TERMAL POWER to 94% or less of RATED THERMAL POWER. With a F (Z) factor exceeding [F (Z)]g by greater than 4 percent, b. reduce THERMAL POWER to 94% or less of RATED THERMAL POWER within 15 minutes. i

  1. The APDMS may be out of service when surveillance for determining power distribution maps is being performed.

1 NORTH ANNA - UNIT 1 3/4 2-17 k %^

1 POWER DISTRIBUTION LIMITS 1 } a j. SURVEILLANCE REQUIREMENTS 4.2.6.1 F (Z) shall be determined to be within_its limit by: a. Either using the APDMS to monitor the thimbles required per Specification 3.3.3.8 at the following frequencies. 1. At least once per 8 hours, and 2. Immediately and at intervals of 10, 50, 60, 90, 120, 240 and 480 minutes following: 4 j a) Increasing the THERMAL POWER above 94% of RATED j THERMAL POWER, or b) Movement of control bank "D" more than an accumulated total of 5 steps in any one direction. 4 b. Or using the movable incore detectors at the following fre-quencies when the APDMS is inoperable: 1. At least once per 8 hours,.and 2. At intervals of 30, 60, 90,120, 240 and 480 minutes following: + a) Increasing the THEPM/L POWER above 94% of RATED THERMAL POWER, or b) Movement of control bank "D" more than an accumulated total of 5 steps in any one direction. 4.2.6.2 When the movable incore detectors are used to monitor F (Z), 3 l at least 2 thimbles shall be monitored and an F (Z) accuracy equivalsit l to that obtained from the APDMS shall be maintained. i i i f 1 4 { h t i NORTH ANNA - UNIT 1 3/4 2-18 i i i e ,-_.,-,,w+= .,--m-g,,,--rv.-,i,,.4 +e. .-......-,-.~-.,--v---ym,,,w,,wy,-v,,,_y--w-r-,---.-.--e ..----v., ---w-- w, -,-y. y-et-~y -+-mr. r - f*-~

1 3/4.2 POWER DISTRIBUTION LIMITS BASES The specifications of this section provide assurance of fuel integrity during Condition I (Normal Operation) and II (Incidents of Moderate Frequency) events by: (a) maintaining the minimum DNBR in the core > 1.30 during normal operation and in short term transients, and (b) limiting the fission gas release, fuel pellet temperature & cladding mechanical properties to within assumed design criteria. In addition, limiting the peak linear power density during Condition - I events provides assurance that the initial conditions assumed for the LOCA analyses are met and the ECCL acceptance criteria limit of 2200 F is not exceeded. The definitions of certain hot channel and peaking factors as used in these specific'ations are as follows: F (Z) Heat Flux Hot Channel Factor. is defined as the maximum local q heat flux on the surface of a fuel rod at core elevation Z divided by the average fuel rod heat flux, allowing for man-ufacturing tolerances on fuel pellets and rods. Nuclear Enthalpy Rise Hot Channel Factor, is defined as the H ratio of the integral of linear power along the rod with the highest integrated power to the average rod power.

  • Y(Z)

Radial Peaking Factor, is defined as the ratio of peak power F density to average power density in the horizontal plane at core elevation Z. 3/4.2.1 AXI3L FLUX DIFFURENCE (AFD) The limits on AXIAL FLUX DIFFERENCE assure that the F (Z) upper bound q l envelope of 2.14 times the nor=alized axial peaking factor is not exceeded during either normal operation or in the event of xenon redistribution-following power changes. Target flux difference is determined at equilibrium xenon conditions. The full length rods may be positioned within the core in accordance with their respective insertion limits and should be inserted near their normal position for steady state operaticn at high power levels. The value of the target flux difference obtained under these conditions divided by the fraction of RATED THERMAL POWER is the target flux difference at RATED THERMAL POWER for the associated core burnup conditions. Target flux differences for other THERMAL POWER levels are obtained by multiplying the RATED THERFJJ. POWER value by the appropriate fractional THERMAL POWER level. The periodic updating of the target flux difference valae ia necessary to reflect core burnup considerations. NORTH ANNA - UNIT 1 B 3/4 2-1

POWER DISTRIBUTION LIMITS BASES Although it is intended that the plant will be operated with the AXIAL FLUX DIFFERENCE within the :5% target band about the target flux difference, during rapid plant THERMAL POWER reductions, control rod motian wi.ll cause che AFD to deviate outside of the target band at reduced THERMAL POWER levels. This deviation will not affect the xenon redistribution sufficiently to change the envelope of peaking factors which may be reached on a subsequent return to RATED THERMAL POWER (with the AFD within the target band) provided the time duration of the deviation is limited. Accordingly, a 1 hour penalty deviation lit:it cumulative during the previous 24 hours is provided for operation outside of the target band but within the limits of Figure 3.2-1 while' at THERMAL POWER levels between 50% and 84% of RATED THERMAL POWER. For THERMAL POWER levels between 15% and 50% of RATED THERMAL POWER, deviations of the AFD outside of the target band are less significant. The penalty of 2 hours actual time reflects this reduced significance. Provisions for monitoring the AFD on an automatic basis are derived from the plant process computer through the AFD Monitor Alarm. The computer determines the one minute average of each of the OPERABLE excora detector l outputs and provides an alarm message immediately if the AFD for at least 2 OPERABLE excore channels are outside the target band and the THERMAL POWER is greater than 84% of RATED THERMAL POWER. During operation at THERMAL POWER levels between 50% and 84%.nd 15% and 50% RATED THERMAL POWER, the computer outputs an alarm message when the penalty deviation accumulates beyond the limits of I hour and 2 hours, respectively. Figure B 3/4 2-1 shows a sypf cal monthly target band. NORTH ANNA - UNIT 1 B 3/4 2-2 Q.-

POWER DISTRIBUTION LIMITS BASES 3/4.2.5 DNB PARAMETERS The limits on tne DNB related parameters assure that each of the parameters are maintained within the nors:al steady state ennlope of operation assumed in the transient and accident analyses. The limits are consistent with the initis' FSAR assumptions and have been analytically demonstrated adequate to maintain a minimum DNBR of 1.30 throughout each analyzed transient. Tne 12 hour periodic surveillance of these para =eters thru instrument readout is sufficient to ensure that the parameters are restored within their limits following load changes tud other expected transient operation. The 18 month periodic measurement of the RC'i total flow rate is adequate to detect flow degradation and ensure correlation of the flow indication channels with measured flow such that the indicated percent flow will provide sufficient verification of flow rate on a 12 hour basis. 3/4.2.6 AXIAL ?OWER DISTtlouTION The limit on axial power distribution ensures that F will be controlled q and monitored on a more exact basis through use of the APDMS when operating above 94% of RATED THERMAL POWER. This additional limitation on F is q necessary in order to provide *ssurance that peak clad temperatus.s will remain below the ECCS acceptano. criteria limit of 2200 F h the event of a LOCA. NORTH ANNA - UNIT 1 B 3/4 2-6

1 Unit 2 Technical Specifications ?

3/4.2 POWER DISTRIBUTION LIMITS AXIAL FLUX DIFFERENCE (AFD) LIMITING CONDITION FOR OPERATION 3.2.1 The indicated AXIAL FLUX DIFFERENCE (AFD) shall be maintained within a 25* target band (flux difference units) about the target flux difference. APPLICABILITY: MODE 1 ABOVE 50% RATED THERMAL POWER

  • ACTION:

a. With the indicated AXIAL FLUX DIFFERENCE outside of the 25% target band about the target flux difference and with THERMAL ?OWER: 1. Above 82* of RATED THERMAL POWER, within 15 minutes: l a) Either restore the indicated AFD to within the target band limits, or b) Reduce THERMAL POWER to less than 82" of RATED l THERMAL POWER. 2. Between 50% and 82% of RATED THERMAL POWER: l a) POWER OPERATION may continue provided:

1) The indicated AFD has not been outside of the 25% targer band for more than 1 hour penalty deviation etmulative during the previous 24 hours, and
2) The indicat ed AFD is within the limits shown on Figure 3.2-1.

Otherwise, reduce THERMAL POWER to less than 50% of ' LATED THERMAI., POWER within 30 minutes and reduce ele Power Rtnge Neutron Flux-High Trip fetpoints to less than or equal to 55% of RATED THERMAL POWER within the next 4 hours. b) Surveillance cesting of the Power Range Neutron Flux Channels may be performed pursuant to Specification 4.3.1.1.1 provided the indicated AFD is maintained within the limits of Figure 3.2-1. A total of 16 hours of operation may bc accumulated with the AFD outside of the target band during this testing without penalty deviation. ~

  • See Special Test Exception 3.10.2.

NORTH ANNA - UNIT 2 3/4 2-1

POWER DISTRIBUTION LIMITS LIMITING CONDITION FOR OPERATION (Continued) b. THERMAL POWER shall not be increased above 82% of RATED THERMAL POWER unless the indicated AFD is within the 25% target band and ACTION 2.a.1, above has been satisfied, c. THERMAL POWER shall not be increased above 50% of RATED THERMAL POWER unless the indicated AFD h3s not been outside of the 25% target band for more than 1 hour penalty deviation cu=ulative during the previous 24 hours. SURVEILLANCE REOUIREMENTS 4.2.1.1 The indicated - AXIAL FLUX DIFFERENCE shall be detemined to be within its li=its during POWER OPERATION above 15% of RATED THERMAL POWER by: a. Monitoring the indiccted AFD for each OPERABLE excore channel: 1. At least once per 7 days when the AFD Menitor Alarm is OPERABLE, and 2. At.' east once per hour for the first 24 hours after restoring the AFD Monitor Alarc to OPFRABLE status, b. U nitoring and logging the indicated AXIAL FLUX DIFFERENCE for each OPERABLE excore channel at laast once per hour for the first 24 hours and at leset once per 30 minutes thereafter, when the AXIAL FLUX DIFFERENCE Monitor Alam is inoperable. The logged values of the indicated AXIAL FLUX DIFFERENCE shall be assumed to exist during the interval preceding each logging. 4. 1.2 The indicated AFD shall be considered outside of its 25% target vand when at least 2 OPERABLE excore channels are indicating the AFD to be outside the target band. Penalty deviation outside of the 25% target band shall be accumulated on a time basis ofI a. Ore minute penalty deviatien for each ont minute of POWER OPERATION outside of the target band at THERMAL POWER levels equal to or above 50% of RATED THERMAL POWER, and b. One-half minute penalty deviation for each one minute of POWER OPERATION outside of the target band.:: THERMAL POWER levels between 15% and 50% of RATED THERMAL POWER. NORTE ANNA - UNIT 2 3/4 2-2

i t i i I 1 120 I I I ~ i $a:U. l f 1 i i Y., o"1 -{.. 1 fY 'l f i 100 -.-j. i o w -g l -t j ..} -- L in G -} i j. . zg-a ,.j._g.. i.. 4 j I 80 l~ i i t- + -- - f: \\ i-i 1 .'JNACCEPTABLE- --UNACCEPTAHLf noen sTn 1 i-[j \\ l-1 non rrin.1 t .A. ~~ i /i i I.\\ l i. l 60 -i - / -i: -N - - -i. l fi t-q-j- . ;\\ : i..

1 -+ - } - /X~ci:EPTABLE~OFERATION\\: 1

=l =(-25 4 50) il -1 if 25A.ioY i -f !I f. 40 e i I 1 i ~ i i I i. i 1 .I -- l - i~ i i .l -i - Jj - ) ,g I l i i I i l-1 .I 0 i l' +- l' -i- -50 39 -20 -10 0 10 20 30 40 50 FLUX DIFFERENCE (AI)% Figure 3.2-1 Axial Flux Difference Limits as a Function of Rated Thermal Power NORTd ANNA - UNIT 2 3/4 2-4

- _. ~ l l POWER EISTRIBUTION LIMITS HEAT FLUX HOT CHANNEL FACTOR-F LIMITING CONDITION FOR OPERATION 3.2.2 F (Z) nhall be limited by the rollowing relationships: q F (Z) 1 [2.14l [K(Z)]for P > 0.5 1 q P F (Z) i [4.28] [K(Z)]for P 10.5 q where P = THE1LML POWER RATED THERMAL POWER and K(Z) is the function obtained from Figure 5.2-2 for a given core height location. t APPLICABILITY: MODE 1. f ACTION: With F (Z) exceeding its limit: q a. Comply with eithe of the following ACTIONS: 1. Feduce THERMAL POWER at least 1% for each 1% F (Z) exceeds the 9 limit within 15 minutes and similarly reduce the Power Range i Neutron Flux-High Trip Setpoints within the next 4 hours; POWER OPERATION may proceed for up to a total of 72 hours; subsequent FOWER OPERATION may proceed provided the Over..,ver AT Trip Setpoints have been reduced at least 1% for each 1% F (Z) 4 q exceeds tM limit. The Overpower AT Trip Setpoint, reduction shall be performed with the reactor in at least HOT STANDBY. 2. Reduce THERMAL POWER as necessary to meet the limits of Specification _ 3.2.6 using the APDMS with the latest incore map + I and updated R. b. Identify and correct the caves of the out of limit condition prior ,~ to increasing THERMAL POWER above the reduced limit required by a, above; THERMAL POWER may then be increased provided F (Z) is q demonstrsced through incore mapping to be within iu li=1t. l 1 NORTH ANNA - UNIT 2 3/4 2-5 u ey w&w e*+ yy wew vn ee-- y s-w w gwy,...y-,,wyv,--m,w,-,-ar. ,,$--,,e, yn,-,,

1 J i i e q .p cu ; . 3 j i' '-l 8 t ID*bk1*b}!- L.2_q ..i i 1.0 ~ i -i (IUN 33-i{\\ l:

. j

- -i i i t 0.8 I i t-i i i N i 'I f __ !--- ) 0.6 r 1 \\. n g .c

i. -- i

-t i \\ i -. __l = e ......;; - 3. il., u,U. Le 67-i 5 4 5 i 1 a i l ^ N ,h ' x o.9 _ o. - - + .--_ i.. .i 1 -r j _.j _l h . i _-. i .i 1. i t - r r 0 2 4 6 8 10 12 CORE HEIGHT (FT) as a Function of Core Height Figure 3.2-2 K(Z) - Nomalized F (Z) i l NORTH ANNA - UNIT 2 374,_ g l

POWER DISTRIPUTION LIMITS AXIAL POW DISTRIBUTION LIMITING CONDITION FOR OPERATION 3.2.6 The axial power distribution slyll be limited by the following relationship: [2.14] [K(Z)] [F (Z)]3 = j (R )(P )(1.03)(1 + o})(1.07) Where: a. F (Z) is the nomalized axial pcwer distribution from thimble j at core elevation Z. I b. P is the fraction of RATED THERMAL POWER. c. K(2) is the function obtained from Figure 3.2-2 for a given core height location. d. R, for thimble j, is detemined from at least n=6 incore j flux maps covering the full configuration of permissible rod patterns above 91% of RATED THERMAL POWER in accordance with: 1 E= R j t 1=t i' Where: eas 01 ij [F (Z)]Ma and [F (Z)] is the maximam value of the normalized axial distribution at elevation Z from thimble j in map i i ~ L l NORTH ANNA - UNIT 2 3/4 2-17 i

POWER DISTRIB1TIION LIMITS fIMITING CONDITION FOR CPERATION (Continued) which had a measured peaking factor without uncertainties eas or densification allowance of F e) is the standard deviation associated with thimble j, expressed e. as a fraction or percentage of.R), and is derived from n flux maps from the relationship below, or 0.02, (2%) whichever is greater. ( n11 i=1(I - Rij)) g. j j I J f. The factor 1.07 is comprised of 1.02 and 1.05 to account for the axial power distribution instrumentation accuracy and the measure-ment uncertainty associattd with F using the movable detector q l system, respectively. 4 g. The factor 1.03 is the engineering uncertainty-factor. APPLICABILITY-MODE 1 ABOVE 91% OF RATED THERMAL POWER. 4 ACTION: a. With a F (Z) facter excee' ding [F (Z)]g by less than or equal to

  • 3 percent, reduce THERMAL POWER one percent for every percent by which
  1. The APDMS may be out of service when surveillance for determining i

~ power distribution maps is being performed. i NORTH ANNA - UNIT 2 3/4 2-18 L f

L i l POWER DISTRIBUTIOK f.ITS ACTION (Continued) j the F (Z) factor exceeds its limit within 15 minutes and wit.hin the 3 next two hours either reduce the F)(Z) factor to within its limit or reduce THERMAL POWER to 91% or less of RATED THERMAL POWER. With a F)(Z) f actor exceeding [F (Z)]g by greater than 4 percent, b. reduce THERMAL POWER to 91% or less of RATED THERMAL POWER within 15 minutes. SURVEILLANCE REQUIRE 1ENTS i a A 4.2.6.1 F (Z) shall be determined to be within its limit by: 2 a. Either using the APDMS to monitor the thimbles required per Specification 3.3.3.8 at the following frequencies. 1. At least once per 8 hours, and 2. Immediately and at intervals of 10, 30, 60, 90, 120, 240 and 480 minutes following: a) Increasing the THERMAL POWER above 91% of RATED THERMAL POWER, or b) Movement of control bank "D" more than an accumulated total of 5 steps in any one direction. b. Or using the movable incere detectors at the following fre-quencies when the APDMS is inoperable: 1. At least once per 8 hours, and 2. At intervals of 30, 60, 90,120, 240 and 480 minutes following: NORTH ANNA - UNIT 2 3/4 2-19

N POWER DISTRIBUTION LIMITS SURVEILLANCE REQUIREMENTS (Cantinued) a) Increasing the THERMAL POWER above 91% of RATED l ^ THERMAL POWER, or b) Movement of control bank "D" more than an recumulated total of 5 steps in any one direction. 4.2.6.2 Wha.n the movable incore detectors are used to monitor F (Z), at least 2 thimbles shall be monitored and an F (Z) accuracy equivalent: 3 to that obtained from the APDMS shall be maintained. If a l F I 4 1 1 i 1 I 4 t h l NORTH ANNA - UNIT 2 3/4 2-20

3 /4..: POWER DISTRIBUTION LIMITS BASES The specifications of this ser. tion provide assurance of fuel integrity during Condition I (Nomal Operation) and II (Incidents of Moderate Frequency) events by: (a) maintaining the minin.um DNBR in the core greater than or equal to 1.30 during normal operation and in short term transients, and (b) limiting the fission gas release, fuel pellet temperature & cladding mechanical properties to within assumed design criteria. In addition, limiting the peak linear power density during Condition I evente provides assurance that the initial conditions assumed for the LOCA analyses are met and the ECCS acceptance criteria limit of 2200 F is not exceeded. The definitions of certain hot channel and peaking factors as used in these specifications are as follows: F (Z) Heat Flux Hot Channel Facto., is defined as the maximum local q heat flux on the surface of a fuel rod at core elevation Z divided by the average fuel rod heat flux, allowing for man-ufacturing to L rances on fuel pellets and rods. N F; Nuclear Enthalpy Rise Hot Channel Factor, is defined as the ratio of the integral of linear power along the rod with the highest integrated power to the average rod power.

  • 7(Z)

Radial Peaking Factor, is defined as the ratio of peak power F density to average power density in the horizontal plane at core elevation Z. 3/4.2.1 AXIAL FLUX DIFFERENCE (AFD) The limita on AXIAL FLUX DIFFERENCE assure that the F (Z) upper bound q l envelope of 2.14 times the normalized axial peaking factor is not exceeded during either normal operation or in the event of xenon redistribution following power changes. Target flux difference is determined at equilibrium xenon conditions. The full length rods may be positioned within the core in accordance with their respective insertion limits and should be inserted near their normal position for steady state operation at high power levels. The va? se of the target flux difference obtained under these conditions divided by the Ccaction of RATED THERRod, POER is the target flur utfference at RATED THERMAL POWER for the associated core burnup conditions. Target flux differences for other NORTH ANNA - UNIT 2 B 3/4 2-1

POWER DISTRIBUTION LI*1ITS BASES THERMAL POWER levels are obtained by multiplying the RATED THEREL POWER value by the appropriate fr:tetional THERMAL POWE' level. The periodic updating of the target flux difference value is necessary to reflect core burnup considerations. Although it is intended that the plant will be operated with the AXIAL FLUX DIFFERENCE within the 15% target band about the target flux difference, during rapid plant THERMAL POWER reductions, control rod motion will cause the AFD to deviate outside of the target band at reduced THERMAL POWER levels. This deviation will not affect the xenon redistribution sufficiently to change the envelope of peaking tactors which may be reached on a subsequent return to RATED THERMAL POWER (with the AFD within the target band) provided the time duration at the deviation is limited. Accordingly, a 1 hour penalty deviation limit cumulative during the previous 24 hours is provided for operation outside of the target band but within the limits of Figure 3.2-1 while at l THERMAL POWER levels between 50% and 82% of RATED THERMAL POWER. For THERMAL POWER levels between 15% and 50% of RATED THEFliAL POWER, deviations of the AFD outside of the target band are less significant. The penalty of 2 hours actual time reflects this reduced significance. Provisions for monitoring the AFD on an autcmatic basis are derived f rom the ' ant process couputer through the AF'i Monitor Alarm. The computer deter:Lnes the one minute average of each of the OPERABLE excore detector outputs and provides an alarm message irmediately if the AFD for at least 2 l OPERABLE excore channels are outside the target band and the THERMAL POWER is greater than 82% of "ATED THERMAL POWER. During operation at THERMAL POWER levels between 50% and 82% and 15% and 50% RATED THERMAL POWER, the computer outputs an alarm message when the penalty deviatic,n accumulates beyond the limits of 1 hour and 2 hours, respectively. s Figure B 3/4 7-1 etows a typical monthly target band. l NORTH ANNA - UNIT 2 B 3/4 2-2

POWER DISTRIBUTION LIMITS BASES 3/4.2.5 DNB PARAMETERS The limits on the DNB related parameters assure that each of the parameters are maintained within the normal steady state envelope of operation assumed in the transient and accident analynes. The limits are consistent with the initial FSAR assumptions and have been analytically demonstrated adequate to caintain a minimum DNBR of 1.30 throughout each analyzed transient. The 12 hour periodic surveillance of these parameters thru instrument readout is sufficient to ensure that the parameters are restored wichin their limits following load changes and other expected transient operation. The 18 month periodic measurement of the RCS total flow rate is adequate to detect flow degradr. tion and ensure correlation of the flow indication channels with measured flow such that the indicated percent flow will provide sufficient verification of flow rate on a 12 hour basis. 3/4.2.6 AXIAL POWER DISTRIBUTION The limit on axial power distribution ansures that F will be controlled q and =enitored on a more exact basis through use of the APDMS when operating l above 91% of RATED THERMAL POWER. This additional limitation on F is q necessary in order to provide assurance that peak clad tecperatures will remain below the ECCS acceptance criteria limit of 2200*F in the event of a LOCA. NORT11 ANNA - UNIT 2 B 3/4 2-6 l}}

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