ML20137K512

From kanterella
Jump to navigation Jump to search
Proposed Tech Specs Allowing Implementation of Relaxed Power Distribution Control
ML20137K512
Person / Time
Site: North Anna Dominion icon.png
Issue date: 01/16/1986
From:
VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML20137K505 List:
References
NUDOCS 8601240116
Download: ML20137K512 (41)
v • d • e


Text

T ATTACHMENT I PROPOSED TECHNICAL SPECIFICATION CHANCES.FOR NORTH ANNA UNIT 2 yh ,,

P

+

+ - _ _ - -

INDEX LIMITING CONDITIONS FOR OPERATION AND SURVEILLANCE REOUIREMENTS SECTION PAGE 3/4.2 POWER DISTRIBUTION LIMITS 3/4.2.1 Axial Flux Difference.................................. 3/4 2-1 3/4.2.2 Heat Flux Hot Channel Factor........................... 3/4 2-5 3/4.2.3 Nuclear Enthalphy Hot Channel Factor................... 3/4 2-9 3/4.2.4 Quadrant Power Tilt Rat 1o.............................. 3/4 2-12 3/4.2.5 DNB Parameters......................................... 3/4 2-15 3/4.3 INSTRUMENTATION 3/4.3.1 REACTOR TRIP SYSTEM INSTRUMENTATION.................... 3/4 3-1 3/4.3.2 ENGINEERED SAFETY FEATURE ACTUATION SYSTEM INSTRUMENTATION...................................... 3/4 3-15 3/4.3.3 MONITORING INSTRUMENTATION Radiation Monitoring................................... 3/4 3-38 Movable Incore Detectors............................... 3/4 3-42 Auxiliary Shutdown Panel Monitoring Instrumentation.... 3/4 3-43 Accident Monitoring Instrumentation.................... 3/4 3-46 a

Fire De tection Inst rumentation. . . . . . . . . . . . . . . . . . . . . . . . . 3/4 3-49 i

Radioactive Liquid Effluent Monitoring Instrumentation 3/4 3-53 Radioactive Gaseous Effluent Monitoring Instrumentation 3/4 3-60 3/4.4 REACTOR COOLANT SYSTEM 3/4.4.1 REACTOR COOLANT LOOPS AND COOLANT CIRCULATION J

Startup and Power Operation............................. 3/4 4-1 H o t S t a ndb y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3/4 4-2 Shutdown................................................ 3/4 4-3 Isolated Loop........................................... 3/4 4-4 Isolated Loop Startup................................... 3/4 4-5 NORTH ANNA - UNIT 2 IV 2 -

INDEX BASES SECTION PAGE 3/4.0 APPLICABILITY ............................................... B 3/4 0-1 3/4.1 REACTIVITY CONTROL SYSTEMS 3/4.1.1 BO RATION CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B 3 / 4 1 - 1 3/4 1.2 BORATION SYSTEMS .......................................... B 3/4 1-3 1

3/4 1.3 MOVABLE CONTROL ASS EMBL IES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B 3 /4 1-4 ,

I 3/4.2 POWER DISTRIBUTION LIMITS 3/4.2.1 AXIAL FLUX DI FFERENCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B 3 /4 2 -1 3/4.2.2 and 3/4.2.3 HEAT FLUX AND NUCLEAR ENTHALPY HOT CHANNEL FACTORS ........................................... B 3/4 2-4 3/4 2.4 QUADRANT POWER TILT RATIO ................................. B 3/4 2-5 3/4.2.5 DNB PARAMETERS ............................................ B 3/4 2-6 NORTH ANNA - UNIT 2 Xa

3/4.2 POWER DISTRIBTUION LIMITS AXIAL FLUX DIFFERENCE (AFD) j LIMITING CONDITION FOR OPERATION 3.2.1 The indicated AXIAL FLUX DIFFERENCE (AFD) shall be maintained within the allowed operational space defined by Figure 3.2-1.

APPLICABILITY: MODE 1 ABOVE 50: RATED THERMAL POWER ACTION:

a. With the indicated AXIAL FLUX DIFFERENCE outside of the Figure 3.2-1 '

limits, 1.) Either restore the indicated AFD to within the Figure 3.2-1 limits within 15 minutes, or 2.) Reduce THERMAL POWER 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 percent of RATED THERMAL POWER within the next 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, f

b. THERMAL POWER shall not be increased above 50% of RATED THERMAL POWER unless the indicated AFD is within the Figure 3.2-1 limits.

SURVEILLANCE REOUIREMENTS 4.2.1.1 The indicated AXIAL F*.UX DIFFERENCE shall :e determined to be within its limits during POWER OPERATION above 50*. of RATED THERMAL POWER by:

4

a. Monitoring the indicated AFD for each OPERABLE excore channel:
1. At least once per 7 days when the AFD Monitor Alarm is OPERABLE, and

! 2. At least once per hour for the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> .after restoring the AFD Monitor Alarm 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 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and at least once per 30 minutes thereaf ter, when the AXIAL FLUX DIFFERENCE Monitor Alarm is inoperable. The logged values of 2

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 limit when at lease 2 OPERABLE excore channels are indicating the AFD to be outside of the limit shown in Figure 3.2-1.

NORTH ANNA - UNIT 2 3/4 2-1

Figure 3.2-1 is provided in the Core Surveillance Report as per TecFrdcal Specification 6.9.1.7.

l Figure 3.2 Axial Flux Difference Limits as a Function of Rated Thermal Power ;

NORTH AMiA - UNIT 2 3/4 2-2

This page has been left blank intentionally.

t b

t i

NORTH ANNA - UNIT 2 3/4 2-3

- __ -. . ~ _ . ,

This page has been left blank intentionally.

NORTH ANNA - UNI'. 2 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:

Fq (Z) s[ 2.20] [K(Z)] for P> 0.5 P

Fq (Z) s[4.40] [K(Z)] for Ps 0.5 where 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.

ACTION:

With Fq(Z) exceeding its limit
a. Reduce THERMAL POWER at least 1% for each 1% F (Z) exceeds the limit within 15 minutes and similarly reduce the Power0 Range Neutron Flux-High Trip Setpoints within the next 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />; POWER OPERATION may proceed for up to a total of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />; subsequent POWER OPERATION may proceed provided the Overpower AT Trip Setpoints i

(value of K g) have been reduced at least 1% (in AT span) for each 1%

Fq (Z) exceeds the limit.

b. Identify and correct the cause 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 providedgF (Z) is demonstrated through incore mapping to be within its limit.

1 NORTH ANNA - UNIT 2 3/4 2-5

POWER DTSTRIBUTION LIMITS SURVEILLANCE REQUIREMENTS 4.2.2.1 The provisions of Specification 4.0.4 are not applicable.

4.2.2.2 by:

Fq (z) shall be evaluated to determine if9F (z) is within its limit

a. Using the movable incore detectors to cbtain a power distribution map at any THERMAL POWER greater than 5 percent of RATED THERMAL POWER.
b. Increasing the measured F 0 (z) component of the power distribution map by 3 percent to account for manufacturing tolerances and further increasing the value by 5 percent to account for measurement uncertainties,
c. Satisfying the following relationship:

F (z) s 2.20 x K(z) for P> 0.5 P x N(z)

F (z) s 2.20 x K(z) for Ps 0.5 N(z) x 0.5 where FF(z) is the measured F z increased by the allowances for

=anufackuringtolerancesandka(as)urement oncertainty, 2.20 is the F limit, K(z) is given in Figure 3.2-2, P .4 the relative THERMAL q

POWER, and N(z) is the cycle dependent ft:nction that accounts for power distribution transients encounterec during normal operation.

This function is given in the Core Surveillance Report as per Specification 6.9.1 7.

d. Measuring F (z) according to the following schedule:
1. Upon achieving equilibrium conditions after exceeding the THERMAI POWER at which F (z) was last determined by 10 percent or more of RATED THERMAL POWER *, or
2. At least once per 31 effective full power days, whichever occurs first.

J

  • During power escalacion, the power level may be increased until a power level for extended operation has been achieved and a power distribution map obtained.

NORTH ANNA - UNIT 2 3/4 2-6

POWER DISTRYBUTTON LIMITS SURVEILLANCE REQUIREMENTS (Con't.)

e. With measurements indicating maximum
  • ~ *

[ F (z) uz) ,

has increased since the previous determination of F (z) either of the following actions shall be taken:

1. F9 (z) shall be increased by 2 percent over that specified in 4.2.2.2.c. or
2. F (z) shall be measured at least once per 7 effective full p her days until 2 successive maps indicate that maximum F'(z) over z is not increasing.

( g(,) )

f.

With the relationships specified in 4.2.2.2.c above not being satisfied:

1. Calculate the percent F0 (z) exceeds its limit by subtracting one from the measurement / limit ratio and multiplying by 100:

(

i =aximum F (z) over z  !

-1 x 100 for P 20.5

.O x K(z)

( P x N(z)

J f

maximum F (z)

< over z -1 x 100 for P <0.5

.O j x

g 0.5 x N(z) g(=))

2. Either of the following actions shall be taken
a. Power operation may continue provided the AFD limits of Figure 3.2-1 are reduced 1% AFD for each percent F (z) exceeded its limit, or 9
b. Comply with the requirements of Specification 3.2.2 for F9 (z) exceeding its limit by the percent calculated above.

NORTH ANNA - UNIT 2 3/4 2-7

POWER DISTRIBUTION LIMITS SURVEILLANCE REQUIREMENTS (Con't.)

g. The limits specified in 4.2.2.2.c, 4.2.2.2.e. and 4.2.2.2.f above are not applicable in the following core pit.ue regions:
1. Lower core region 0 to 15 percent inclusive.
2. Upper core region 85 to 100 percent inclusive.

4.2.2.3 When F (z) is measured for reasons other than meeting the requirements of9 Specification 4.2.2.2 an overall measured F 0(z) shall be obtained from a power distribution map and increased by 3 percent to account for manufacturing tolerances and further increased by 5 percent to account for measurement uncertainty.

A 4

1 i

1 j

NORTH ANNA - UNIT 2 3/4 2-7a

Pages 3/4 2-17 through 3/4 2-20 are to be deleted.

This page has been left blank intentionally.

NORTH ASNA - UNIT 2 3/4 3-31

~*

This page has been left blank intentionally.

NORTH ANNA - UNIT 2 3/4 3-52

1 . ,

i SPECIAL TEST EXCEPTIONS l GROUP HEIGHT, INSERTION AND POWER DISTRIBUTION LIMITS LIMITING CONDITION FOR OPERATION 3.10.2 The group he igh t ',' insertion and power distribution limits of Specifications 3.1.3.1, 3.1.3.5, 3.1.3.6, and 3.2.4 may be suspended during r.he performance of PHYSICS TESTS provided:

a. The THERMAL POWER is maintained less than or equal to 85% of RATED THERMAL POWER, and
b. The limits of Specifications 3.2.2 and 3.2.3 are maintained and determined at the frequencies specified in Specification 4.10.2.2.

below.

APPLICABILITY: MODE 1.

ACTION:

With any of the limits of Specifications 3.2.2 or 3.2.3 being exceeded while the requirements of Specifications 3.1.3.1, 3.1.3.5, 3.1.3.6, and 3.2.4 are suspended, either:

a. Reduce THERMAL POWER suf ficient to satisfy the ACTION requirements of Specifications 3.2.2 and 3.2.3, or
b. .Se in HOT SIANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

SURVEILLANCE REQUIREMENTS 4.10.2.1 The THERMAL POWER shall be determined to be less than or equal to 85% of RATED THERMAL POWER at least once per hour during PHYSICS TESTS.

4.10.2.2 The Surveillance Requirements of the below listed Specifications shall be performed at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> during PHYSICS TESTS.

a. Specification 4.2.2.2 and 4.2.2.3.
b. Specification 4.2.3.1and4.d.3.2.

\

NORTH ANNA - UNIT 2 3/4 10-2 w

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 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 eve.nts 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:

Eq (2) Heat Flux Hot Channel Factor, is defined as the maximum local 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.

Ff~H Nu lear 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 r:d power.

3/4.2.1 AXIAL FLUX DIFFERENCE (AFD)

The limits on AXIAL FLUX DIFFERENCE assure that the Fq (Z) upper bound envelope, as given in Specification 3.2.2, is not exceeded during either normal operation or in the event of xenon redistribution following power changes.

NORTH ANNA - UNIT 2 B 3/4 2-1

POWER DISTRIBUTION LIMITS BASES e

f 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 excore detector outputs and provides an alarm message immediately if the AFD for at least 2 of 4 or 2 of 3 OPERABLE excore channels are outside the allowed AI-power operating space and the THERMAL POWER is greater thin 50% of RATED THERMAL FO'a'ER .

I 1

NORTH ANNA - UNIT 2 B 3/4 2-2

This page has been left blank intentionally.

NORTH ANNA - UNIT 2 8 3/4 2-3 1

POWER DISTRIBUTTON LZMITS BASES When F H is measured, 4% is the appropriate experimental error allowance for a Yull core map t ken with the incore detection system. The specified limit for H also contains an 8% allowagee for uncertainties which means that norm 1 operation will result in F H less than or equal to 1.55/1.08. The8%allowanceisbasedcathefoklovingconsiderations:

a. abnormal perturbations in ghe radial power shape, such as from rod misalignment, ef fect F' 3 H aore directly than Fq, T
b. although rod movement has a direct influence upon limiting Fq towithgnitslimit, such concrol is not readily available to limit F H, and 3

c.

errors in prediction for control power shape detected during startup physics tests can be compensated for inO F byJestrict-ing axial flux distributions. This compensation ror r H is less readily available. 3 The cyclehotandchannel factor F'bbower factoris height depende measured

, N(Z), to provideperiodically assurance and that increase the limit on the hot channel factor, Fn (Z), is met. N(Z) accounts for the non-equilibrium effects of normal Operatien transients and was determined from expected power control maneuvers over the full range of burnup conditions in the core.

The N(Z) function for normal operation is provided in the Core Surveillance Report per Specification 6.9.1.7.

3/4.'.' .4 OUADRANT POWER TILT RATIO The quadrant power tilt ratio limit assures that the radial power distribution analysis.

satisfies the design values used in the power capability Radial power distribution measurements are made during start-up testing and periodically during power operation.

The limit of 1.02 at which corrective action is required provides DNB and linear heat generation rate protection with x-y plane power tilts.

The two hour time allowance for operation with a tilt condition greater than 1.0 but less than 1.09 is provided to allow identification and correction of a crepped or misaligned rod. In the event such action does not correct the tilt, the margin for uncertainty on qF is rein-stated by reducing the pcwer by 3 percent for each percent of tilt in excess of 1.0.

NORTH ANNA - UNIT 2 B 3/4 2-5

_ .- , . _ . ._~

POWER DISTRIBUTION LIMITS BASES For purposes of monitoring QUADRANT POWER TILT RATIO when one excore detector is inoperable, the moveable incore detectors are used to confirm that the normalized symmetric power distribution is consistent with the QUADRANT POWER TILT RATIO. The incore detector monitoring is done with a full incore flux map or two sets of 4 symmetric thimbles. The two sets of i

4 symmetric thimbles is a unique set of 8 detector locations. These locations are C-8 E-5 E-11, N-3, H-13, L-5, L-11, and N-8.

3/4.2.5 DNB PARAMETERS The limits on the DNB related parameters assure chas each of the parameters are maintained within the normal steady state envelope of operation assumed in the transient and accident analyses. The limits are consistent with the initial FSAR assumptions and have been analytically demonstrated-adequate to maintain a minimum DNBR of 1.30 throughout each analyzed transient.

The 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> periodic surveillance of these parameters thru instrument readout is sufficient to ensure that the parameters are restored within their li=its following load changes and other expected transient operation. The 18 month periodic measurement of the RCS total flow rs:e is adequate to detect flow degradation and ensure correlation of the fic. indication channels with measured flow such that the indicated percent flow will provide sufficient verification of flow rate on a 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> basis.

NORTH ANNA - UNIT 2 B 3/4 2-6

l INSTRUMENTATION BASES 3/4.3.3.7 FIRE DETECTION INSTRUMENTATION OPERABILITY of the fire detection instrumentation ensures that adequate warning capability is available for the prompt detection of fires. This capability is required in order to detect and locate fires in their early stages. Prompt detection of fires will reduce the potential for damage to safety related equipment and is an integral element in the overall facility fire protection program.

In the event that a portion of the fire detection instrumentation is inoperable, the establishment of frequent fire patrols in the affected areas is required to provide detection capability until the inoperable instrumentation is restored to OPERABILITY.

3/4.3.3.8 This section has been deleted.

NORTH ANNA - UNIT 2 B 3/4 3-3

ADMXNISTRATIVE CONTROLS CORE SURVEILLANCE REPORT 6.9.1.7 The N(Z) function for normal operation and the Axial Flux Difference limits (T.S. Figure 3.2-1) shall be provided to the Regional Administrator, Region II, with c copy to:

Director, Office of Nuclear Reactor Regulation Attention: Chief, Reactor Systems Branch Division of PWR Licensing-A U. S. Nuclear Regulatory Commission Washington, D. C. 20555 at least 60 days prior to cycle initial criticality unless otherwise approved by the Commission by letter. In the event that this information would be submitted at some other time during the core life, it shall be submitted 60 days prior to the date the information would become effective unless otherwise approved by the Commission by letter.

Any information needed to support N(Z) and/or the Axial Flux Difference limits will be by request from the NRC and need not be included in this report.

NORTH ANNA - UNIT 2 6-18

ADMINISTRATIVE CONTROLS (Continued)

ANNUAL RADIOLOGICAL ENVIRONMENTAL OPERATING REPORT

  • 6.9.1.8 Routine Radiological Environmental Operating Reports covering the operation of the unit during the previous calendar year shall be submitted prior to May 1 of each year. The initial report shall be submitted prior to May 1 of the year following initial criticality.

The Annual Radiological Environmental Operating Reports shall include summaries, interpretations, and an analysis of trends of the results a ! the radiological environmental surveillance activities for the report period, including a comparison (as appropriate) with preoperational studies, operational controls, and previous environmental surveillance reports, and an assessment of the observed impacts of the plant operation on the environment.

The reports shall also include the results of land use censuses required by Specification 3.12.2.

The Annual Radiological Environmental Operating Reports shall include the results of analysis of all radiological environmental samples and of all environmental radiation measurements taken during the period pursuant to the locations specified in the Table and Figures in the ODCM, as well as summarized and tabulated results of these analys=4 and measurements in the format of the table in the Radiological Assessment Branch Technical Position, Revision 1. November 1979. In the event that some individual results are not available for inclusion with the report, the report shall be submitted noting and explaining the reasons for the missing results. The missing data shall be submitted as soon as possible in a supplementary report.

The reports shall also include the following: a summary description of the radiological environmental monitoring program; at least two legible maps **

covering all sampling locations keyed to a table giving distances and directions from the centerline of one reactor; the results of licensee participation in the Interlaboratory Comparison Program, required by i

Specification 3.12.3; discussion of all deviations from the sampling schedule of Table 4.12-1 and discussion of all analyses in which the LLD required by Table 4.12-3 was not achievable.

.i a

' *A single submittal may be made for a multiple unit station.

    • 0ne map shall cover stations near the SITE BOUNDARY; a second shall include the more distant stations.

NORTH ANNA - UNIT 2 6-19 I

O e

ATTACHMENT 2 DISCUSSION OF PROPOSED CHANCES

l DISCCSSION OF PROPOSED CHANGES 1

, INTRODUCTION I

L

! i The heat flux hot channel f actor (FQ) operating limit specified in the North Anna Technical Specifications is established by LOCA/ECCS analyses performed in accordance with 10 CFR 50 Appendix K. These analyses show that if the FQ limit is not exceeded, the predicted LOCA peak clad temper-ature will not exceed the 2200*F limit specified in the Final ECCS Accept-1 ance Criteria. The Technical Specifications also -tablish the required method for verification that the actual peaking dtor realized during operation will not exceed the axially dependent puking factor (FQ(Z))

limit.

i

,j I

This verification is currently performed by combining the axially depend-I ent radial peaking factor, Fxy(Z), which is determined t.y periodic sur-veillance with the core flux monitoring system, with an analytically determined axial peaking factor (PZ(Z), Refs.1-2). 'The determination of

{ PZ(Z) involves evaluating various plant operating manuevers such as load following. The analysis currently assumes the Constant Axial Offset Con-trol (CACC) operating strategy discussed in Reference 1. During CAOC i

operation, the measured core axial flux difference (AFD) is maintained I

t 1

l

1 J

within a fixed band (+ or - 5*) of a target value. The target AFD is established by equilibrium operating conditions.

The proposed changes will replace the CAOC AFD limits with a set of limits established by the Relaxed Power Distribution Control (RPDC) methodology discussed in Reference 2. The important feature of the RPDC strategy is that, instead of analytically verifying the peaking factor (FQ) margin for a fixed AFD limit band, the AFD band is varied until the available FQ mar-gin, which increases as power decreases, is utilized. Because a wider range of axial shapes can be realized under RPDC normal operation, addi-tional analyses must be performed to verify that the overtemperature delta-T (OTDT) and overpower delta-T trips continu- to provide adequate DSB and local overpower (high kw/f t) protection over the entire range of anticipated Condition II events. In addition, the shapes are evaluated as potential preconditions for the Complete I.oss of Flow accident, to ensure that no DSB violations would occur during the bounding, non-0 TDT protected accident. The methodology for performing this verifi-cation is discussed in further detail in Reference 2.

i Additionally, the current requirement for monitoring the axially depend-ent radial peaking factor, Fxy(Z), is being replaced by a requirement to monitor the total peaking factor TQ(Z). This is accomplished by taking a full core flux map under equilibrium and increasing the measured value by appropriate factors to account for manufacturing tolerances and measure-2

nent uncertainties. Finally, since the FQ(Z) is measured under equilibrium conditions, a nonequilibrium factor, N(Z), is applied. N(Z) accounts for the maximum potential increase in local peaking which could occur during transient, nonequilibrium operation. In accounting for the transient effects, N(Z) thus has a function which is similar to PZ(Z) in the current approach. The difference is that where PZ(Z) is a nonequilibrium axial peaking factor, N(Z) envelopes the potential equilibrium-to-nonequilibrium FQ increase and accounts for both axial and radial xenon and power redistribution effects.

ITEM BY ITEM DISCUSSION OF CHANCES

1. Replacement of CAOC Axial Flux Difference (AFD) Limits with RPDC Limits (Sections 3.2.1, 4.2.1, B3/4.2.1 and 3.10.2)

All references to the indicated AFD target and operating band have been deleted, replacing them with AFD limits consistent with the RPDC methodology of Reference 2. These limits will be provided on a cycle specific basis in the Core Surveillance Report. In the Action Statement associated with the Limiting Condition for Operation (LCO), the requirement to restare the indicated AFD to within the limits within 15 minutes has been retained. If this requirement is not met, power must be reduced to less than 50% of rated within 30 minutes. As discussed in Reference 2, maintaining the AFD within the prescribed limits will ensure that: 1) the maximum expected FQ(Z) will not exceed the limit specified in Section 3.2.2; 2) the axial power 3

. ~ - . ~ . .. . _ . . _ = - . - -.- . .

i I

i distribution in the core will not fall outside the range of preconditions j used to ensure that the overtemperature delta-T and overpower delta-T 1

functions provide adequate core protection ; and 3) the UFSAR analysis of

) the Complete Loss of Flow event remains limiting. The lower limit of 50*

i i

power on imposing AFD lieits is consistent with the current Technical Spe-I cifications.

1 i

Reference to the Special Test Exception of Section 3.10.2 has been removed from Section 3.2.1. Thus the specified axial flux difference limits will 1 apply during the performance of physics tests, l-i 4

2. Deletion of the Requirement to place the Reactor in at least Hot i

Standby to Reduce the Overpower Delta-T Trip Se: paint (Section 3.2.2,

?

Action a) -

The requirement to place the unit in Hot Standby in order to reduce the j Overpower delta-T trip setpoint has been deleted since the reduction can be performed, one channel at a time, while at power.

i l

4 i

i j .

l I

! 4

3. Removal of all References to the Axial Fower Distribution Monitoring System (APDMS) (Section 3.2.2, Action a.2, Sections 3.2.6, B 3/4.2.6, 6.9.1.7)-

Under the existing Specifications, use of APDMS is required at or above power levels for which the product of the analytically predicted FQ (from the load follow analysis dicussed previously) and power exceeds the cur-rent LOCA limit. Under the RPDC philosophy, the operating limits on axial of fset are established to ensure that the FQ LOCA limit is not exceeded.

Thus the cycle-to-cycle variations in analytically predicted maximum FQ (and therefore APDMS turn-on power level) which occur under the existing specifications will be eliminated. Rather, the del:a-I (Axial Flux Dif-ference) envelope is now the i=portant analysis on:put variable that is subject to cycle-by-cycle analytic verification. The revised Specifica-tions provide a =ethod for compensating for any FQ violations that could potentially occur under nonequilibrium conditions by narrowing the Delta-I limits. APDMS is a redundant measure and therefore not required for operation with RPDC/FQ surveillance.

5

4. Replacement of Fxy Surveillance Requirement with FQ Surveillance (Sections 4.2.2, B3/4.2, B3/4.2.3, 6.9.1.7) -

The existing specifications require periodic verification that FQ(Z) remains below its limit by monitoring the radial peaking factor Fxy(Z) and comparing to a cycle-specific limit. This limit is established such that 1

the maximum product of the Fxy(Z) limit and the analytically predicted nonequilibrium axial peaking factor PZ(Z) remains below the FQ(1) limit (Ref.1). The revised specifications require a direct seasurement of FQ at least once per 31 effective full power days. The measured - FQ is then increased by the nonequilibrium factor N(Z) to account for power distrib-ution transients during normal operation. Development of the cycle-specific N(Z) factor negates the requirement to generate the axial peaking factor (PZ(Z)) for each reload cycle. Since FQ is measured directly, the requirement for cycle-dependent Fxy surveillance is no lon-i ger necessary.

i f

3

(

I

_ _ _ _ _ _ _ _ _ _ . _ _ _ _ - - - _ - _ _ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ' ^ -

5. Modification of the Core Surveillance Report (Section 6.9.1.7)

As discussed previously. FQ surveillance requires the use of the N(Z) function as a cycle specific multiplier on FQ(measured) in order to incorporate nonequilibrium effects. The Core Surveillance Report provides this function to the commission on a cycle-by-cycle basis, replacing the

, current requirement to provide the Fxy limit, the surveillance power level l and the FQ flyspeck. The Core Surveillance Report also contains the cycle j specific Axial Flux Difference limits for Technical Specification 3.2.1. '

j SAFETY EVALUATION RESULTS Virginia Electric and Power Company has performed a detailed review of the impact of operation with Relaxed Power Distribution Control /FQ Surveillante on the various accident scenarios discussed in Chapter 15 of the North Anna UFSAR. Specifically, the impact of the wider axial flux difference on key safety parameters which could influence accident analysis results has been assessed. Among those parameters considered are: trip reactivity, both total value and reactivity as a function of rod insertion; shutdown margin;

reactivity insertion rates due to rod withdrawal from suberitical and at power; and rod worths and/or peaking factors for ejected, dropped or misaligned control rods.

I This review has demonstrated that, apart from the RPDC limit generation

! procedures discussed in detail in Reference 2, no changes will be required

)

J 7

to the other safety analysis methods described in Reference 3 to incorpo-rate the effect of the widened delta-I band resulting from the RPDC meth-odology. The current analysis methods used by Virginia Electric and Power Company already employ a conservative method for incorporating the offacts of skewed axial power distributions. As is currently the practice, the accident analyses will continue to be evaluated on a reload basis for RPDC operation to ensure that the key input parameters remain bounding. Should an accident analysis be determined to be impacted by a specific reload design, that accident will be evaluated or reanalyzed, as appropriate.

APPLICATICS TO L3IT 2 CYCLE 4 The North Anna Unit 2 Cycle 4 (50C4) reload core des.;n has been evaluated for operation under the proposed RPDC Technical Spec;fications in accord-ance with the methodology presented in Reference 2. The analysis included examination of the LOCA and complete Loss of Flow Accident (LOFA) precon-ditions, the peak linear power (kw/ft), the overtemperature delta-T f(delta-I) function and the fuel rod design criteria. Each analysis was performed at beginning, middle and end of cycle. The analysis results yielded two conclusions:

1) none of the normal operation conditions allowed by RPDC were found to violate the key safety criteria, and 2) all of the Condition II events examined in the FSAR were shown to yield acceptable results when initiated from an> of these normal operation con-
  • ditions.

The RPDC bands were thus found to be an acceptable operating space.

8 w___ _ ---_______ - ___-_ --_ _ _ _ _ _ _ _ - _ _ _ - _ _ - - - _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ - _ _ _ _ _ _ - - _ _ - _ - _ - _ - _ _ _ _ _ _ -

10 CFR 50.59 SAFETY REVIEW Based on a detailed safety evaluation, Virginia Electric and Power Company ,

has concluded that implementation of the proposed Relaxed Power Distrib-ution Control / FQ Surveillance Technical Spec'ifications will not intro-duce an unreviewed safety question as defined in 10 CFR 50.59.

Specifically:

1. Since the proposed changes involve only a relaxation of the limits in axial power distribution skewing, neither the prob-ability of occurrence nor the consequences  ;: any accident or malfunction of equipment important to safety previously evaluated in the safety analysis report is increased L- these proposed changes. Furthermore, the RPDC analysis procedures and continued application of current reload design and safety analysis methodology will ensure that the UFSAR accident analyses remain bounding.

2 The proposed changes do not involve any alterations to the physical plant which introduce any new or unique operational modes or accident precursors. Thus the possibility for an accident or malfunction of a different type than any evaluated previously in the safety analysis report is not being created 9

i 1

+

l by these proposed changes.

3. htile a relaxation of the axial offset operating limits is .

realized, the margin of safety as defined in the basis for any i

technical specification is not reduced by these proposed changes; the margins of safety are preserved by the imposition of a frequent FQ surveillance requirement and by effectively reducing the limit on measured equilibrium FQ by a conservative nonequilibrium factor, N(Z).

L 10 CFR 50.92 SIGNIFICANT HAZARDS REVIEW i

i j The proposed changes do not pose a significant hazards consideration as j

defined in 10CFR50.92. This conclusion is based upon Example vi of those -

s types of license amendments that are considered unlikely to involve sig-(

ntficant hazards considerations. Example vi, which was published in the Federal Register, Vol. 48, No. 67. April 6,1983, p. .870, " Standards for Determining Whether License Amendments Involve No Significant Hazards Considerations, Interim Final Report," cites "a change which either may .

result in some increase to the probability or consequences of a previously analyzed accident or may reduce in some way a safety margin, but where the I results of the change are clearly within all acceptable criteria with t respect to the systems or components specified in the Standard Review j

10

Plan." Virginia Electric and Power Company's evaluation shaws that all of the acceptance criteria for the transient analyses presented in the UFSAR are met and the appropriate safety margins are maintained.

REFERENCES

1. Morita, T., et al.: " Topical Report- Power Distribution Control Load Following Procedures," WCAP-8385, Westinghouse Electric Corporation, (September 1974).
2. Basehore, K., et al. " Relaxed Power Distribut.;n Control Methodology and Associated FQ Surveillance Techn. 21 Specifications,"

VEP-NE-1, Virginia Electric and Power Company, (C.tober 1984).

3. Bordelon, F. M., et al.: " Westinghouse Reload Safety Evaluation Methodology," WCAP-9272, Westinghouse Electric Corporation, (March 1978).

11

ATTACHMENT 3 i

CORE SURVEILLANCE REPORT FOR NORTH ANNA UNIT 2. CYCLE 4

NORTH ANNA UNIT 2 CYCLE 4 CORE SURVEILLANCE REPORT This Core Surveillance Report is provided in accordance with Section 6.9.1.7 of the North Anna Unit 2 Technical Specifications.

The burnup-dependent Cycle 4 N(z) function for Technical Specification 4.2.2.2 is shown in Figures 1-3. N(z) was calculated according to the procedure of VEP-NE-1.

The N(z) function

  • will be used to confirm that the heat flux hot channel factor, F0(z), will be limited to the Technical Specifications values of FQ(z) 5 2.20 K(z), P >0.5 and P

F0(z) 1 4.40 K(z), P < 0.5.

The Cycle 4 Axial Flux Difference (AFO) limits for Technical Specification 3.2.1 are shown in Figure 4. These Ifmits were calculated according to the nethods of VEP-NE-1.

The limits on Axial Flux Difference assure that the F0(z) upper bound envelope is not exceeded during either normal operation or in the event of xenon redistribution following power changes.

  • The N(z) function, when applied to a power distribution reasured under equilibrium conditions, demonstrates that the initial conditinnt. assumed in the LOCA analysis are net, along with the ECCS acceptance criteria of 10CFR50.46, 84R629RCA207

10P Ar4D BOT 10!! 15 PLRCt:11 LXCLUDfD A', Pill ti(1) IutiCT10N IL Clift ! CAL $PL C l f l L A T 10:1 4. 2. 2. 2. C 140RIt: ANNA Uiill 2 CYCLL 4 BURNUPS LESS lilAN 7,000 flWD/tiTU I IILIGilf N(Z) 0.19 .

0.56 . -

0.94 .

1.31 .

1.69 g 1.4 -

2,06 g -

1.333

~ 2.44 1.30d 2.81 f

3. 9 1.279 1.247

> 3.do 1.227 J .

3.94 1.215 D 1.3 - - -- -

4.31 1.201

! I 4.69 1.183 S.06 1.161 l I 5.44 1.154 g  %

S.Sl 6.19 1.169 1.200 A 6.56 1.225 1.2 g ( 6.94 1.241 3 1 7.31 a 1.246 0 b 7.69 1.240 O 0.06 1.231

  1. a.44 1.224 I 8.81 1.217 0 9.19 1.200 l

I l.1 - - -

9.56 1.180 9.94 1.133 10.31 .

10.69 .

11.06 .

11.44 .

11.11 .

I 8 2 4 8 8 le 12

EEM .

, Figure 1 - !0R111 Klilifill 2 CYfil~ 1 1;1(D 1111Clifn FOR Bti4RA*i LESS ItW17,llh i&D411u

N(Z) FUNCTION 10P AilD B0110i.15 Pf!:CINT iXCLUDiD A'2 l'l 1: NORTil ANNA UNIT 2 CYCLE 4 TLCliHICAL SPI Cll lCAl l0N /. 2.2..'.G BURNOPS I!ETWEEN 7,000 AND 14,700 MWD /Miu g3 1101G11I N(Z) 0.19 .

0.56 .

0.94 . .

1.31 .

1.69 .

g'g_ ,_ _ _._ _ .

2.06 1.197 E

2.44 1.182 9 2.Pil 1.16S J 3.13 1.151

, b 3.56 1.146 l y 3.94 1.145 l

J 4.31 1.153 3 gj. . _ . _ _ ._ __ __ ____ _ ___._

4.69 1.155 3 5.05 1.154 5.44 1.136 3 5.ill 1.212 3

g h 6.19 1.230 6.S6 1.245 g 6.91 1.257

= gy .. . _ _ ._ _._ . - - . __

7.31 1.250 d 7.69 1.246 3 3.05 1.23d O S.44 1.226 0 #

S.J1 1.217

% 9.13 1.202' O 9.5G 1.184 1 g,g _ .

9.94 1.1c9 10.31 .

10.69 .

11.06 .

11.44 .

!!.01 .

1 l

8 2 4 6 8 14 12 mmpur) .

riouve 2 _ WMil Km IIllT 2 CYCtf 31 CID llIlCIlai r0R BUHWS BETE (EN 7,00 AND I1,/.h it.id61Ill

. _ - - - _ = _ . . _ . . .-- _ -. __ - . _ --- - - ___ _ - __-._ __-_ _ _ _ _ _ ___. __ - _ . _ _ - - _ - - . _ ..

N(Z) fuf4CTI0f4 TOP AND 80IIOl1 !S P1RCilll LXCL0010 AS P1!: NORili AN*4A UNIT 2 CVCLC 4 ILCli!;ICAL SPLCIllCAllull 4.2.2.2 G BURiluPS Gi< EATER TilA:l 14.700 FED /t1TU g3 ____

llEICllI N(Z) l l l 0.19 .

0.55 .

l 0.94 . ,

! 1.31 .

g 1.69 .

g,4 .__ _ . . _ .

__1. _ _. _ __ __

2.06 1.197 8 2.41 1.182 E 2 .*11 1.165 J l 3.19 1.151 l

3.S5 1.146 y 3.94 1.145 J ,

4.31 1.153 3 33 ___.

L_ . . _ .. _ _ _ .

4.69 1.15S 3 5.06 1.154 S.44 1.136 3 I S.81 1.212 3  % 6.19 6.56 1.230 1.245 g

g 6.94 1.257

= g2 8

____ ___ 7.31 1.258 d l ,

7.69 1.246 3  ; .

J.05 1.238 8.44 0 I 1.226 l M k '

l 3.81 1.209 Z j 9.19 1.134 0 l 9.56 1.134 1 l 9.9<  !.139 1.3 10.31 .

10.69 .

11.06 .

11.44 .

11.01 .

g __.

s 4 2 4 4 8 it 12 M M lf E f)

Figure 3 - lGilli A'in Itill 2 CYCLE 4 (~12) III!CTilti fOR buh!3UPS U1A1LR lilMI III,Ml IUD /mu

120

~

1IO

(-15.100) (+< ,,100) 100 -

,- . I 1

E , / ace.e.. .1. ( a ee m.u.

, , - e... .

X 70 x - . . ..

~

3:

60 / \,

O 50 /

- \, ;

g ..> ..,., ...,

g 40 h

O 30 an to 10 0 g

-50 -30 -10 10 30 50 FLUX DIFFERENCE (DELTA-1) PERCEhT

Figure 4 - Axial flux Difference Limits as a function of Rated Thermal Power for North Anna Unit 2 Cycle 4

__ _

Retrieved from "https://kanterella.com/w/index.php?title=ML20137K512&oldid=2832688"