ML20235M415

Cycle 6 Core Performance Rept

ML20235M415
Person / Time
Site:	North Anna
Issue date:	05/31/1987
From:	Farley M, Ford C, Snow C VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML20235M405	List: ML20235M402 ML20235M415
References
VP-NOS-32, NUDOCS 8707170188
Download: ML20235M415 (49)

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VP-NOS-32 l l

l

\

NORTH ANNA UNIT 1, CYCLE 6 -

CORE PERFORMANCE REPORT {

i t

by i

'l 1 M. K. Farley i

}

Reviewed: Approved: J J

~

)

e c2 C. A. Ford, Staff Engineer c.JL C. T. Snow, Supervisor

)

Nuclear Fuel Operation Nuclear Fuel Operation J l

k Operations and Maintenance Support Subsection Nuclear Operations Department 1 Virginia Electric and Fower Company )

l Richmond, Virginia 6 May, 1987  !

1 l

l 4

l' l l l l

i I

l I

l l

l r CLASSIFICATION / DISCLAIMER

1

\ l

\

i l The data, techniques, information, and conclusions in this report have been j 4

prepared solely for use by the Virginia Electric and Power Company (the

)

Company), and they may not be appropriate for use in situations other than )

l those for which they were specifically prepared. The Company therefore makes no claim or warranty whatsoever, express or implied, as to their ]

j accuracy, usefulness, or applicability. In particular, THE COMPANY MAKES 1 i

NO WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, NOR SHALL ANY WARRANTY BE DEEMED TO ARISE FROM COURSE OF DEALING OR USAGE OF TRADE, with respect to this . report or any of the data, techniques, information, or conclusions in it. By making this report available, the Company does not authorize its use by others, and any such use is expressly forbidden except with the prior written approval of the Company. Any such l

written approval shall itself be deemed to incorporate the disclaimers of '

liability and disclaimers of warranties provided herein. In no event shall the Company be liable, under any legal theory whatsoever (whether contract, j I tort, warranty, or strict or absolute liability), for any property damage, mental or physical injury or death, loss of use of property, or other 1

damage resulting from or arising out of the use, authorized or unauthorized, of this report or the data, techniques, information, or I conclusi in it.

i i

i I

1 1

f l 1

)

I 1

1 1

TABLE OF CONTENTS i

1 t

! SECTION TITLE PAGE NO.

1 I

Classification / Disclaimer . . . . . . . . . . . .i l

List of Tables .... . . . . . . . . . . . . . iii )

List of Figures . . . . . . . . . . . . . . . . iv 1 Introduction and Summary. . . . . . . . . . . ..I l 2 Burnup Follow . ... . . . . . . . . . . .. . .7 3 Reactivity Depletion Follow . . . . . . . . . . . 14 4 Power Distribution Follow . . . . . . . . . .. . 16 5 Primary Coolant Activity Follow . . . . . . . . . 37 6 Conclusions .. .... . . . . . . . . . .. . 41 7 References. .. .... . . . . . . . . . . . . . 42 I

• 11

l i

l i

LIST OF TABLES  !

I i

TABLE TITLE PAGE NO.

4.1 Summary of Flux Maps for Routine Operation . . . . . . . . . 20 t

i

)

I l

111

l I

l l

l i

LIST OF FIGURES l 1

FIGURE TITLE PAGE NO.

4 1.1 Core Loading Map . . . .................... 4 1.2 Movable Detector and Thermocouple Locations. . . . . . . . . .5 1.3 Control Rod Locations. ...... . . . . . . . . . . . . .6 2.1 Core Burnup History . ... . . . . . . . . . . . . . . . . .9 2.2 Monthly Average Load Factors . . . . . . . . . . . . . . . . . 10 l J

l 2.3 Assemblywise Accumulated Burnup: Measured and Predicted . . 11 1 2.4 Assemblywise Accumulated Burnup: Comparison of Measured and Predicted . . . . . . . . . . . . . . . . . . . 12 2.5 Sub-Batch Burnup Sharing . . . . . . . . . . . . . . . . . . . 13 3.1 Critical Boron Concentration versus Burnup - HFP-ARO . . . . . 15 4.1 Assemblywise Power Distribution - N1-6-09 . . . . . . . . . 22 4.2 Assemblywise Power Distribution - N1-6-19 . . . . . . . . . . 23 l

4.3 Assemblywise Power Distribution - N1-6-33 . . . . . . . . . . 24 l 4.4 Hot Channel Factor Normalized Operating Envelope . . . . . . . 25 4.5 Heat Flux Hot Channel Factor, F (Z) - N1-6-09 . . . . . . . . 26 4.6 Heat Flux Hot Channel Factor, F (Z) - N1-6 . . . . .. . . 27 4.7 Heat Flux Hot Channel Factor, F (Z) - N1-6-33 . . . . . . . . 28 4.8 Maximum Heat Flux Hot Channel Factor, F q*P, vs.

Axial Positiot. . . . . .... . . . . . . . . . . . . . . . 29 4.9 Maximum Heat Flux Hot Channel Factor, F-Q, versus Burnup . . . 30 4.10 Enthalpy Rise Hot Channel Factor, F-DH(N), versus Burnup . . 31 4.11 Target Delta Flux versus Burnup . . . . . . . . . . . . . . . 32 IV

i I

I LIST OF FIGURES CONT'D i FIGURE TITLE PAGE NO.

i i

i 4.12 Core Average /.xial Power Distribution - N1-6-09 . . . . . . . 33 4.13 Core Average Axial Power Distribution - N1-6-19 . . . . . . . 34  !

4.14 Core Average Axial Power Distribution - N1-6-33 . . . . . . . 35 4.15 Core Average Axial Peaking Factor, F-Z, versus Burnup . . . . 36 q

5.1 Dose Equivalent I-131 versus Time . . . . . . . . . . . . . . 39 a 5.2 I-131/I-133 Activity Ratio versus Time . . . . . . . . . . . 40 1

1 I

v

f f

i I

Section 1 l

l l

l l INTRODUCTION AND

SUMMARY

On April 19, 1987, North Anna Unit 1 completed Cycle 6. Since the initial criticality of Cycle 6 on December 23, 1985, the reactor core produced approximately 93 x 10' MBTU (15,705 Megawatt days per metric ton of contained uranium), which has resulted in the generation of approximately 9.2 x 10' WHr gross (8. 7 x 10' KWHR net) of electrical energy. The purpose of this report is to present an analysis of the core performance for routine operation during Cycle 6. The physics tests that were performed during the startup of this cycle were covered in the North Anna Unit 1, Cycle 6 Startup Physics Test Report and, therefore, will not 2

be included here.

On August 27, 1986 North Anna Unit 1 executed a core uprate to 2893 MWth from 2775 MWth. The core follow data and core peaking factors reflect this uprate.

North Anna Unit 1 was in coastdown from March 27, 1987, at which time the burnup was approximately 14,842 MVD/MTU. The coastdown, therefore, accounted for an additional core burn of 863 MWD /MTU from the end of full power reactivity.

The sixth cycle core consisted of five batches of fuel: a twice burned batch from North Anna 1, Cycles 4 and 5 (batch 6A); two once-burned batches 1

l from North Anna 1, Cycle 5 (batches N1/7A and N2/5B); and two fresh batches (batches 8A and 8B). The North Anna 1, Cycle 6 core loading map specifying the fuel batch identification, fuel assembly locations, burnable poisons locations and source assembly locations is shown in Figure 1.1. Movable detector locations and thermocouple locations are shown in Figure 1.2.

Control rod locations are shown in Figure 1.3.

Routine core follow involves the analysis of four principal performance indicators. These are burnup distribution, reactivity depletion, power distribution, and primary coolant activity. The core burnup distribution is followed to verify both burnup symmetry and proper batch burnup sharing, thereby ensuring that the fuel neld over for the next cycle will be compatible with the new fuel that is inserted. Reactivi.ty depletion is monitored to detect the existence of any abnormal reactivity behavior, to determine if the core is depleting as designed, and to indicate at what burnup level refueling will be required. Core power distribution follow includes the monitoring of nuclear hot channel f actors to verify that they are within the Technical Specifications

• limits, thereby ensuring that adequate margins for linear power density and critical heat flux thermal limits are maintained. Lastly, as part of normal core follow, the primary coolant activity is monitored to verify that the dose equivalent iodine-131 concentration is within the limits specified by the North Anna Unit 1 Technical Specifications and to assess the integrity of the fuel.

Each of the four performance indicators is discussed in detail for the North Anna Unit 1, Cycle 6 core in the body of this report. The results are summarized below:

2

I i

1. Burnup Follow -

The burnup tilt (deviation from quadrant symmetry) on the core was no greater than 0.21% with the burnup accumulation in each batch deviating from design prediction by less than 1.5%.

2. Reactivity Depletion Follow -

The critical boron concentration, used to monitor reactivity depletion, was consistently 1

within 0.31% AK/K of the design prediction which is well within the 1%

AK/K margin allowed by Section 4.1.1.1.2 of the Technical Specifications.

l 3. Power Distribution Follow - Incore flux maps taken each month indicated that the as s emblyvise radial power distributions deviated from I the design predictions by an average difference of 1.6%. The hot channel factors met their respective Technical Specifications limits.

4. Primary Coolant Activity Follow - The average dose equivalent iodine-131 activity level in the primary coolant during Cycle 6 was apprey.imately 3.1 x 10 -2 pCi/gm. This corresponds to approximately 3% of the operating limit for the concentration of radiciodine in the primary coolant.

3

(

Figure 1.1 NORTH ANNA UNIT 1 - CYCLE 6 CORE LOADING MAP R P N M L k J H G F E D C B A F51 $61 F60 1

002 G37 H41 TT H33 G42 G28 4DP 4DP 2 l W~ $65 H29 12P C12 H49 20P G13 H45 1EP 77 F18 3

F68 G48 H01 "T.T6~~ H37 C16 ' H53 "C H04 TII~ F27 j 12P 20P SS 20P 12P 4 i TT $59 H07 G20 H12 F66 3 75[~ Hl4 G16 H23 $62 G38 l

12P 16P i 16P 12P S l

Gl9 M48 12P G24 Hl6 G21 H21 G26 TF TTF ~H19 C23 H30 C47 16P 20P 20P 166 12P 6

, F61 H36 MI H56 F46 H03 F43 H10 F02 HOS F56 H38 'G14 H42 77 40P 20P 20P 12P 20P 20P 4DP 7 l

G56 F64 ~WH 20P GO) G18 006 H06 12P F40 HOP W G55 G33 H50 ~ F !.J "' Cl?

12P SS 20P 8 FSO H44 C54 H40 7IT"* H24 F39 #12 0 F21 H17 F16 H54 G10 H34 F17 40P 20F 20P 12P 20P 20P 4DP 9 G04 H32 G$1 HIS C53 ~7 H "DUT~ Hl3 G49 H22 G32 H46 Y 12P 15P 20P 20P 16P 12P 10 C22 $43 H25 12P G31 Hl8 16P W- G06 F35 H26 G58 HOS $58 G25 16 P 12P 11 TC G35 H11 G29 H55 G45 H39 052 H09 G44 F53 12P 20P SS 20P 12P 12 F58 N~ H47 12P G50 H51 20P G03 -H31 j 12P

$64 W 13 G46 C40 H35 F23 H43 G59 C27 4DP 4DP 14 l --> ASSEMBLY ID F'9 C39 W l --> ONE OF THE FOLLOWING 15 l

A. SS - SECONDARY SOURCE B. XXP - BURNABLE PolSON ASSEMBLY (XX-NUMBER OF RODS)

C. 4DP - 4 DE PLET[D SURNABLE POISON ROD CLUSTER FUEL ASSEMBLY DESIGN PARAMETERS SUB-BATCH N2/SB 7A 6A 8A BB l INITI AL ENRICHMENT (W/0 U235) 3.59 3.50 3.59 3.60 3.80 ASSEMBLY TYPE 17).17 17X17 17X17 17X17 17X17 NUMBER OF ASSEMBLIES 9 59 33 28 28 FUEL RODS PER ASSEMBLY 264 264 264 264 264 ASSEMBLY IDENilflCATION S$7 - $65 Col + C59 F02,F04,F07,F13,F16 H01 = H28 H29

• H56 F18,F21,F23,F26,F27, F30,F31,F33 F35,F37 F39,F40,F43,F46,F50-F53,F56,F58,F60,F61 F64,F66,F68,F69

_ _ _ _ _ _ _ _ _ . _ _ _ _ _ . _ _ _ _ . . _ _ _ _ . _ _ _ . ___ A

I

(

\

)

Figure 1.2 NORTH ANNA UNIT 1 - CYCLE 6 i

MOVABLE DETECTOR AND THERMOCOUPLE LOCATIONS' R P N M L K J H C F h.' j D C 0 A MD TC s 1 lr TC TC MD 2 MD l MD MD TC TC l MD TC j, TC TC 3 s

i TC MD i ND MD TC 4

', ~~ ~

MD MD TC MD TC TC MD l

' HD TC MD <

TC ' 5 MD TC TC MD TC MD 6 TC TC MD MD MD TC MD MD 7 MD MD HD MD TC TC TC 1C TC TC MD TC TC MO TC 8 MD l TC MD TC ., '

MD TC 4, MD 9 MD 7D~ ~~M b-TC 1 TC TC , MD 1 TC 1D

• MD MD TC MD TC TC TC MD 11 MD MD MD TC '

TC TC MD TC 12

~~

MD MD TC TC 13 MD TC MD TC 14 MD - Movable Dettktor TC - The rmocouple MD TC TC 15 1

5

Figure 1.3 NORTH ANNA UNIT 1 - CYCLE G CONTROL ROD LOCATIONS R P N H L K J H G F E D C B A 18 [

l Loop C Loop B Outlet Inlet 1

IA D A .I 2

, ,,1 ~

W SA l SP N-43 3 C . B ,

B C

i 4 SP l SB SP SB

~~

l f 4- 5 A I "

l Loop C B lD C D B A i 1 i 6 Inlet i SA SB SB SP SA l_ Loop 9 90 - D lC '

~ " ~

C D

1. ut'*t D 7

- 270 8 i SA SP ,

SB SB

'~

l SA 9 l

A , _\ l B 0 C D 1 B A i I l 10 SB SP SB SP 11 C B f B C '

1 1 l 12 SP I SA SA l ~~~

N-44 ,

13 i A N-42 D A 14 Loop A l 15 Abso rbe r pA Outlot Material inlet I

Ag-in-Cd 00 Function Number of' Clusters Cont rol Bank D 8 Control Bank C 8 Control Bank B 8 Control Bank A 8 Shutdown Bank $8 8 Shutdown Bank SA 8 SP (Spare Rod Locetlons) 8 6

(

l Section 2 BURNUP FOLLOW The burnup history for the North Anna 1, Cycle 6 core is graphically depicted in Figure 2.1. The North Anna 1, Cycle 6 core achieved a burnup of 15,705 MWD /MTU. As shown in Figure 2.2, the average load factor for l Cycle 6 was 83.3% when referenced to rated thermal power (2775 W(t) before i

being uprated to 2893 MW(t) on August 27, 1986.)

Radial (X-Y) burnup distribution maps show how the core burnup is shared among the various fuel assemblins, and thereby allow a detailed burnup distribution analysis. The NEWTOTE' computer code is used to calculate these assemblywise burnups. Figure 2.3 is a radial burnup distribution map in which the assemblywise burnup accumulation of the core at the end of Cycle 6 operation is given. For comparison purposes, the design values are also given. Figure 2.4 is a radial burnup distribution map in which the percentage difference comparison of measured and predicted assemblywise burnup accumulation at the end of Cycle 6 operation is also given. As can be seen from this figure, the accumulated assembly burnups were generally within i2.6% of the predicted values. In addition, deviation from quadrant symmetry in the core throughout the cycle was no greater than i0.21%.

The burnup sharing on a batch basis is monitored to verify that the core is operating as designed and to enable accurate end-of-cycle batch burnup predictions to be made for use in reload fuel design studies. Batch definitions are given in Figure 1.2. As seen in Figure 2.5, the batch 7

)

burnup sharing for North Anna 1, Cycle 6 followed design predictions closely with each batch deviating less than 1.5"!, from design. Symmetric burnup in conjunction with agreement between actual and predicted assemblywise burnups and batch burnup sharing indicate that the Cycle 6 core did deplete as designed.

8

Figure 2.1 NORTH ANNA UNIT 1 - CYCLE 6

( CORE BURNUP HISTORY 17000 16000 --- -- - - - - --

---

~ - -- - - ~ ~ -- - -

16000 /

14000 - - - - --- -- -

13000 -

/

C 12000 l 7

E 11000 B 10000 '

u R 9000 '/

p 8000 a M 7000 f 0 6000 M

5000 -

U 4000 ,

3000 f 2000 7

1000  !

7 0,

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 I i 1 1 1 0 J F M R H J J R S 0 N O J F M A N E R E R P R U U U E C 0 E R E R P R C N S R R Y N L G P T V C N B R R Y 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 6 6 6 6 6 6 6 6 6 6 6 6 6 7 7 7 7 7 TIMEtMONTHS1 CYCLE G MAXJMUM OESIGN BURNUP 16500 MWO/MTU

---

BURNUP WINDOW FOR CYCLE 7 OESIGN - 14000 TO 16000 MWO/MTU 9

~~"

==

PERCENT 00 -

80 -

l 0

!!!!!!!!!!!!!!!!! E

'e"e""=ali!";@;jjyjijyl"yj!";j";ijfE!!w

)

I Figure 2.3 NORTH ANNA UNIT 1 - CYCLE 6 ASSEMBLYWISE ACCUMULATED BURNUP MEASURED AND PREDICTED l

(1000 MWD /MTU)

R P N M L M J H C F E D C 8 A 1

1 35.751 24.411 35.831 i MEASURE 0 l 2

.................5 13 1 24 98...... ...331.35.981..............

..... 1.. ..........

PRE 0lCTE0 1 1

l 23.921 28.011 16.35l 30.841 16.44l 28.151 23.891 2 3

.......1 23.441 28.

...... 031.16.6

...... .....N.31.121.16.

..... .....671 28.031

...... 23.44 )

1 35.14) 26.201 18.491 33.281 19.651 32.871 19.001 27.03l 34.831 3

.......1.34.851

..... 26.401.18.771

...... ..... ...... 33.381.19 968.33.381.18.776

. ... ..... ..... ...... ..... 26.401.34.851.......

4 1 35.221 26.391 18.88) 34.561 20.521 35.081 20.301 35.111 19.171 26.751 34.586 4

........l.34.451 ..... 26.621 18.951.34.961

............. 20.641.35.........1

............ 33)20.64 34.961 5

...... ... 18.951 26.621.34.451.......

l 23.491 26.50l 18.641 36.171 20.811 43.201 32.13l 42.701 21.191 36.421 18.821 26.201 23.771 5 6 1.23.41)

............ 26.24f.18.961.36.721.21.091

..... ..... ............ 43.078.32.411 43.07l.21.091...36.721

..... ...... ................ ...... 18 ...... 961 26.241 23.411

.......1l 28.091 18.851 34.501 20.601 37.151 20.301 37.06) 20.301 37.311 20.821 34.411 18.691 28.131 6

28. 048.16.171........ 34 9.11 21.091

...... ......37.111 20.121.36.774 20.121.37.111 21.091 34.911.18.771 7 .......v.... ..... ...... ...... ..... ...... 28.041.......

1 35 1 36.071 16.371 33.191 20.30l 42.351 19.971 42.301 20.861 41.38l 20.261 42.691 19.981 32.751 16.331 7 35.851 8

.... 771 16,66l.33.451.20.641

.......... ..... ............ 42.896 00.101

...... 41.34) 20.691

............. ....... 41,34)

. ... .. 20 101 42 891 20.641 33.451.16.661 35.771 l124.711 24.371 30.551 19.781 34.941 32.011 36.87l 21.041 50.651 20.68) 36.631 31.991 34.581 19.551 30.84! 25.04l

.........30.751 8

9 19.961.35 301 32.311.36.811 20.671 50.291

..... ...... ............. 20.671..........

...... ......... 36.814 32.311 35 301 19.961.30.751 24.71 l 35.691 16.041 32.931 20.361 43.151 19.991 40.751 20.58l 41.071 26.131 42.82l 20.431 33.481 16.601 9 35.721 10 1.35 4771 27,85l16.661

. ................. 33.45l.20.641 42.891 18.304 34.605 21.19)

...... 20.101 41.34l.20.691

...... ...... ...... ............. 41.341 20.101 42.891 20.641 33.45 19.011 28.331 10 11 1..............

28.041 18.771.34.911............ ..... ....... 21.091.37.111

..... ...... ..... 20.121 36.771 20.121.37.111 21.091.34.9 l 23.40) 26.481 19.111 36.821 20.581 42.821 31.92l 42.821 20.861 36.55) 19.261 26.49l 23,75 11 12 .l..............

23.41] 26.241.18.961 36.721

..... ............. ......21.091 43.071 32.414

...... ............. ..... 43.07 4 21.09l.36.721.18.961

.. ... ....... ...1 26.24 l 23.41 l ll 34.111 34.4 27.106 19.05) 34.601 20.03) 34.631 20.1P1 34.481 18.811 27.231 35.031 12

......51 26.621.18.951

....... ............ 34.961

...... 20.641.35.331

..... ....... ..... 20.641 34.95l.18.951

..... ...... .... 26.621.34.451 13 l 35.08l 26.581 18.551 32.631 19.38l 32.76l 18.38l 26.351 35.501 13 14 1.34.851 26.401 18.77) 33.381

..... ..................... 19.961

..... ...... 33.381.18.771

..... ...... .... 26.408.34.854 1

1 23.44) 23.44l 28.451 16.561 31.188 16.231 27.811 23.121 28.03) 16.67 14 15

...................1 . 31.121.16.671 28.03l.23.44!

1 36.481 24.471 36.341 15 1.35

. 981

. . 24.331 35.981 R P N M L k J H 0 F E D C 8 A 11

Figure 2.4 NORTH ANNA UNIT 1 - CYCLE 6 ASSEMBLYWISE ACCUMULATED BURNUP COMPARISON OF MEASURED AND PREDICTED (1000 MWD /MTU)

R P N M L K J H 0 F [ 0 C 8 A 1

1 35.751 24.411 35.831 1 MCAsuRED 1 1 0.64

.....................1.

l l

i 0.3bt.

. . . .0.42).................... .i .M/.P

.. .  %..O l F F......l 2 1 23.921 28.011 16.351 16.44l 28.151 23.891 s

.......1. ..... 2.051. 0.04) .1.871.30.840.891.

............ ..... ...... .....* .... 1.33l. 0.441

.1.951.......

3 1 35.141 26.201 18.491 33.281 19.651 32.871 19.001 27.031 34.831 3

.......1. 0.841. 0.764.

..... ..... 1.491.

...... 0.30) .1.551.

............. ......1.528..1.221. ......0.071.......

2.381.

4 1 35.221 26.391 18.881 34.56l 20.521 35.081 20.301 35.118 19.178 26.751 34.581 4

.......1. 2.231. ..... .....0.851. ......

0.391. 1.151.

..... 0.581. ......0.731. 1.661. 0.421..1.151.

.... ...... ..... ... . 0 ... 488. 0.391.......

5 1 23.491 26.501 18.641 36.171 20.811 43.201 32.131 42.701 21.191 36.421 18.821 26.201 23.771 5

..1 0.311 0.991.

.... ..... .1.671.

. .... ......1.481.

..... 1.331. 0.30) 0.

........ 861. ...0.851.

.....0.451. 0.801......

.... ..... 0.721...... 0.151..1.541 6 1 28.091 18.851 34.501 20.601 37.151 20.301 37,081 20.301 37.311 20.821 34.411 18.601 28.131 6 7

...... 1. 0.171. ..... 0.421. ..... ....1.19.1. ......2.321...... 0.111. ..... 0.871.

.....0.861...... 0.901. 0 561. .....

. ... ...... 1.241...... 1.451. 0.331.......

.....0.441.

1 36.071 16.37) 33.191 20.301 42.351 19.971 42.301 20.861 41.381 20,261 42.69) 19.98l 32.751 16.331 35.851 7

.l .. 841.

0.

.1.641. 1.261. 0.64). . ....... ............1.

1.731 2.32 8

0.791. ..... . .... ...... 0.831.

..... ..... ...........1 0.111. 0.80) 0.48 3.211......

. ..... 2.101. 1.991.

..... 0.25) l 24.374 1 1. 36130.55) 0.651 19.781 34.94) 32.011 36.87 8 21.04) 50.651 20.681 36.631 31.991 34.581 1f.551 30.841 25.041 8 9 ..................... 0.891. 1.03 ......8... 0.921.

.. ..... 0.161..1.

.... .....8 t i......

0. 701. 0.061.-0.

...... ... . 481..0.99

...... ...... ) .2.061.

..... 2.031.

.m 0.301..1. 331 1 35.691 16.041 32.931 20. 361 43.151 19.991 40.751 20. 58 l 41.071 20.131 42.821 20.43 8 33.48 8 16.601 35. 721 9 10

.i....... 0.231. .....3.731.

..... 1.551. 1.361. 0.591. 0.511. 1.431. 0.531. 0.641. 0.164. 0.181

..... ..... .... . ...... .... . ...... ..... ..... ...... 1.001. 0.071. ..... ......0.361. 0.141 1 27.851 18.301 34.601 21.191 36.921 19.601 36.231 20.021 36.561 2

l. 10 1.34 11

..1 230.681.

..... ...... 2.501....... 0.891. 0.5.11.

.. . ...... ......0.501.

......2.601. 1.451.

..... ...... 0.491.

.....1 1.478.

. .1.071..1.281..1.03)

.... .... .... 0.80l 35.291 19.011 28.331

..l .0.041 401 26.0.90 481 19.111 36.821 20.58) 42.821 31.921 4 7.821 20.861 36.551 19.261 26.491 23.751 11 12

...........1. 0.811. 0.2?l .2.421. 0.571..1.504..0.571 1.091. 0.471..1.614. 0.954..1.451 1 34.111 27.101 19.05] 34.601 20.031 34.631 20.181 34,481 18.811 27.231 35.031

) .1.00

.......1 .

2.261 12 13

. .1.781. 0.49) -1.031.

.... ............ .... 2.95.4. 1.99)....... ........ 388 1

.... 2.308..1.691

0. 771.....

l 35.081 26.581 18.551 .................. 13 14

1. .....

0.661.

... 0.69.1. 1.191

....... 2.231. .32.631 2.921..1.861.

..... ..... .... 19.381 32.761 1.8 18.381 2.101..0.181.........

..... 61..

26.351 AVG l ARl7HMCitC 35.501 1

8 23.44l 28.451 16.561 31.18l 16.231 27.811 2 .I. ................

PCT DIFF = .0.361 14 1.34 15 1 STANDARD DEV l

1. .....

0.011..1.521.

. .. ...... 0.651. ..... ...0.201. 2.59.6. 0.786. 3.121...... ............... ......l I 36.481 24.47) 36.341 l AVO ABS PCT I 15

.l .....=.0. 7 4.........I .i..1.38) 0. l DIFF = 1.07

....... 611. 0.991

... ..... ...............i R P N M L k J H 0 F L 0 C 8 A BATCH SHARING (MWD /MTU) BURNLM TILT BATCH CYCLE 4 CYCLE 5 CYCLE 6 TOTALS NW = +0.07 6A 13797 12626 11436 37859 7A --

16218 15047 31265 NE = +0.10 N2/5B --

13263 12988 26251 BA -- --

20083 20083 SW = -0.21 8B -- --

18595 18595 SE = +0.04 CORE AVERAGE = 15705 12

Figure 2.5 NORTH ANNA UNIT 1 - CYCLE 6 SUB-BATCH BURNUP SHARING SUB-BATCH . N1/6 N1/7 N2/58 N1/BR N1/BB SYMBOL .

DIRMOND SQUARE TRIANGLE STAR X 40000 a f 36000 7-s #

d 32000

/

. / /

S a f f B 28000 X-d-

B V / A-

~

A /

T f

24000 -

h

-/

? /

/

8 - f /

U R 20000 --

/= f /_

/ /~ / /

p # # / f '

16000 /A M f //

H f O 77-f fA M 12000 /7 T

U

//

//

A '

8000 #

AY

// ~

//

4000 j ,#

/

/

O-[

0 2000 4000 6000 6000 10000 12000 14000 16000 CYCLE BURNUP MWO/MTU 13

Section 3 REACTIVITY DEPLETION FOLLOW The primary coolant critical boron concentration is monitored for the purposes of following core reactivity and to identify any anomalous reactivity behavior. The FOLLOW" computer code was used to normalize

" actual" critical boron concentration measurements to design conditions taking into consideration control rod position, xenon and samarium concentrations, moderator temperature, and power level. The normalized critical boron concentration versus burnup curve for the North Anna 1, Cycle 6 core is shown in Figure 3.1. It can be seen that the measured data  ;

typically compare to within 41 ppm of the design prediction. This corresponds to less than 0.31% AK/K which is well within the 1% AK/K criterion for reactivity anomalies set forth in Section 4.1.1.1.2 of the Technical Specifications. In conclusion, the trend indicated by the critical boron concentration verifies that the Cycle 6 core depleted as expected without any reactivity anomalies.

14

i Figure 3.1 NORTH ANNA UNIT 1 - CYCLE E CRITICAL BORON CONCENTRATION vs. BURNilP l (HFP, ARO)

X HEASURED -

PRE 01CTED 1800 1600 i

C R

1 1400 T

1 C

R l

1200 E B

A N "

R A k1000 hr .

C  %

C 800  %

E '%

y  %

R R

s 600 k 1 s a wh n g P 400  %

P  %

N -g 200  %

0'.. ... .. .. ,, , ., , ,, , ,,,, ,

0 2000 4000 6000 8000 10000 12000 14000 16000 CYCLE BURNUP (MN0/NTU) 15

Section 4 POWER DISTRIBUTION FOLLOW Analysis of core power distribution data on a routine basis is necessary to verify that the hot channel factors are within the Technical Specifications limits and to ensure that the reactor is operating without any abnormal conditions which could cause an " uneven" burnup distribution.

Three-dimensional core power distributions are determined from movable detector flux map measurements using the INCORE' computer program. A summary of the full core flux maps taken since the completion of startup physics testing for North Anna 1, Cycle 6 is given in Table 4.1. Power distribution maps were generally taken at monthly intervals with additional maps taken as needed.

Radial (X-Y) core power distributions for a representative series of incore flux maps are given in Figures 4.1 through 4.3. Figure 4.1 shows a power distribution map that was taken early in cycle life. Figure 4.2 shows a power distribution map that was taken near mid-cycle burnup.

Figure 4.3 shows a map that was taken at the end of Cycle 6 life. The measured relative assembly powers were generally within 3.5% and the average percent difference was equal to 1.6%. In addition, as indicated by the INCORE tilt factors, the power distributions were essentially symmetric for all cases.

An important aspect of core power distribution follow is the monitoring of nuclear hot channel factors. Verification that these factors are within Technical Specifications limits ensures that linear power density and critical heat flux limits will not be violated, thereby providing adequate thermal margins and maintaining fuel cladding integrity. The Cycle 6 Technical Specifications limit on the axially dependent heat flux hot 16 i

channel factor, Fq (Z), was 2.20 x K(Z) prior to uprating, where K(Z) is I. the hot channel factor normalized operating envelope. After the uprating to 2Pt MWth on August 27, 1986 the limit was 2.15 x K(Z). Figure 4.4 is a plot of the K(Z) curve associated with the 2.20 limit. The axially dependent heat flux hot channel factors, qF (Z), for a representative set of flux maps are given in Figures 4.5 through 4.7. Throughout Cycle 6, l the measured values of qF (Z) were within the Technical Specifications 1

limit. A summary of the maximum values of axially-dependent heat flux hot channel factors measured during Cycle 6 is given in Figure 4.8. Figure 4.9 shows the maximum values for the heat flux hot channel f actor measured during Cycle 6. As can be seen from the figure, there was an approximate 18% margin to the limit at the beginning of the cycle, with the margin generally increasing throughout cycle operation. 1 The value of the enthalpy rise hot channel factor, F-delta H, which is the ratio of the integral of the power along the rod with the highest integrated power to that of the average rod, is routinely followed. The Technical Specifications limit for this parameter is set such that the departure from nucleate boiling ratio (DNBR) limit will not be violated.

Additionally, the F-delta H limit ensures that the value of this parameter used in the LOCA-ECCS analysis is not exceeded during normal operation.

Prior to the uprating, the enthalpy rise hot channel factor limit was 1.55(1+0.3(1-P)); after the uprating the limit was 1.49(1+0.3(1-P)). The 4% measurement uncertainty is not applied to the measured F-delta-H for flux maps taken at the uprated conditions. A summary of the maximum values for the enthalpy rise hot channel factor measured during Cycle 6 is given in Figure 4.10. As can be seen from this figure, the smallest margin to the limit was in the middle of the cycle and was equal to approximately 4.4%.

17

i The Technical Specifications require that target delta flux

• values be determined periodically. The target delta flux is the delta flux which would occur at conditions of full power, all rods out, and equilibrium xenon. Therefore, the delta flux is measured with the core at or near these conditions and the target delta flux is established at this measured point. Since the target delta flux varies as a function of burnup, the target value is updated monthly. Operational delta flux limits are then established about this target value. By maintaining the value of delta flux rele.tively constant, adverse axial power shapes due to xenon redistribution are avoided.

The plot of the target delta flux versus burnup, givan in Figure 4.11, shows the value of this parameter to have been approximately -3.0% at the beginning of Cycle 6. Near the middle of the cycle, delta flux values had shifted to -4.5% and then moved to -4.0% near the end of the cycle. At the end of Cycle 6 delta flux values rose dramatically to +3.5% due to the coastdown. This axial power shift can also be observed in the corresponding core average axial power distribution for a representative series of maps given in Figures 4.12 through 4.14. In Map N1-6-09 (Figure 4.12), taken at 378 MVD/MTU, the axial power distribution had a shape peaked slightly toward the bottom of the core with a peaking factor of 1.20. In Map N1-6-19 (Figure 4.13), taken at approximately 8,170 MWD /MTU, the axial power distribution had become more peaked toward the bottom of the core with an axial peaking factor of 1.15. Finally, in Map N1-6-33 (Figure 4.14), taken at approximately 15,532 MWD /MTU, the axial peaking factor was 1.16, with a slightly concave axial power distribution. The history of F-Z during the cycle can be seen more clearly in a plot of F-Z versus burnup given in Figure 4.15.

Pt-Pb

• Delta Flux = -- -- X 100 where Pt = power in top of core (MW(t))

2893 Pb = power in bottom of core (MW(t))

18

In conclusion, the North Anna 1, Cycle 6 core performed satisfactorily with power distribution analyses verifying that desigt. predictions were accurate and that the values of the Fq(Z) and F-delta H hot channel factors were within the limits of the Technical Specifications.

19

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FIGURE 4.1 NORTH ' ANNA UNIT .1 - CYCLE 6 ASSEMBLYWISE POWER DISTRIBUTION N1-6-09  !

l

}

R P N M L k J H 0 F E O C 8 A

................ ...................... ................ l

. PRE 06CTED .. . O.34 . 0.47 . 0.34 . . PRtDicit0 . l

. MEASURED . . 0.33 . 0.46 . 0.33 . . MCA$URCO . 1

. PCT DIFFERENCE. . -1.4 . -1.5 . -1.3 . . PCT DIFFERENCE.

..;.;g.. 9 5...g ;y..; 3 ...y;;.. 9 5.. 9 5..

. 0.41 . 0.69 . 1.11 . 0.96 . 1.11 . 0.69 . 0.41 . 2  :

. 3.I'. -1.5 . -2.2 . -2,3 . -2.1 . -1.2 . 1.0 .  !

................................... ............................ 1

. 0.38 . 0.87 . 1.20 . 1.25 . 1.24 . 1.25 . 1.20 . 0.87 . 0.38 .

. 0.38 . 0.87 . 1.17 . 1.22 . 1.21 . 1.22 .'1.18 . 0.87 . 0.39 . 3

. 0.7 . 0.4 . 1.9 . -2.7 . 2.8 . 2.3 . -1.1 . 0.4 . 3.3 .

. 0.38 . 0.84 . 1.18 . 1.26 . 1.26 . 1.26 . 1.26 . 1.26 . 1.18 . 0.84 . 0.30

. 0.38 i 0.84 . 1.18 .'1.25 . 1.24 . 1.24 . 1.22 . 1.26 . 1.18 . 0.85 . 0.38 . 4

. 2.0 . O. 2 . -0. 2 . -0. 9 . -1. 7 . - 1. 8 . -2. 6 . 0. 7 . 0.0 . 0.4 0.9 .

.,................a.......... .......-...........,...........................................

. 0.40 . 0.87 1.18 . 1.24 . 1.28 . 1.11 1.23 . 1.11 . 1.28 . 1.24 . 1.18 . 0.87 . 0.40 .

. 0.41 . 0.88 . 1.17 1.22 . 1.27 1.10 . 1.22 . 1.09 . 3.28 . 1.23 . 1.17 . 0.86 . 0.41 . $

. . 0.9 . 0.9 . -1.0 .. -1.7 . -0.9 . =0.7 . -0.8 . -1.2 -0.4 -0.8 . -1.2.. -0.3 . 1.2 .

............................................................................................ l

. 0.70 . 1.20 . 1.26 . 1.28 , 1.22 . 1.16 . 1.20 . 1.16 . 1.22 . 1.28 . 1. 26 . : 1. P0 . 0. 70 .  :

. 0.71 . 1.21 . 1.26 . 1.26 . 1.22 . 1.17 1.21 . 1.17 . 1.22 . 1.27 . 1.25 . 1.19 . 0.70 . 6 'I

. 0.8 . 0.8 . -0.3 . -1.4 .' O.2 . 1.0 . 1.1 . 0.4 . 0.5 . -0.9 . -1.2 . -0.7 . 0.1 .

. 0.34 1.14 1.25 . 1.26 1.11 . 1.?6 . 1.07 1.23 . 1.07 1.16 . 1.11 . 1.26 . 1.25 .;1.14 . 0.34

. 0.34 1.13 . 1.25 . 1.25 . 1.09 . 1.16 . 1.08 . 1.24 1.07 . 1.17 1.10 . 1.24 1.24 . 1.13 . 0.34 7

. 0.8 . -0.3 . =0.3 . -0.7 . -1.0 . 0.2 . 1.0 . 1.2 . 0.5 . 0.8 . -0.4 . -1.6 . -0.8 . -0.6 . 0.1 .

. 0.47 . 0.98 , 1.24 1.P6 . 1.23 . 1.19 . 1.22 . 0.97 1.P2 . 1.19 . 1.23 . 1.26 . 1.24 0.98 . 0.47 .

. 0.46 . 0.98 . 1.23 . 1.26 1.25 . 1.21 . 1.25 . 0.99 . 1.24 1.20 , 1.22 . 1.24 1.23 . 0.98 . 0.47 8

. -I.S . -0.4 -0.5 . 0.3 . 1. 0 . 1.5 . 2.5 . 2.5 . 1.1 . 1.0 . -0.6 . -1.6 . *0.8 . 0.2 . 1.0 .

..................... j

. 0.34 . 1.14 ........ ...................................................... ....................

1.16 . 1.07 1.25 . 1.26 . 1.11 1.23 . 1.07 1.16 . 1.11 1.26 . l.25 . 1.14 0.34 .

. 0.33 . 1.12

-1. $ - 1. 5 . - 1. 6 1.23 . 1.25 1.12 . 1.16 . 1.05 . 1.23 . 1.08 . 1.17 1.11 . 1.25 . 1.25 . 1.15 . 0.34 -9

. -0.2 . 1.2 . 0.1 . -2. 0 . 0.5 . 0.9 . 0. 7 . 0.1 . =0.5 . 0.3 . 0.9 . 1.8 t

................................................. ..... .................................................. .1

. 0.70 . 1.20 . 1.26 . 1.28 1.P2 . 1.16 1.20 , 1.16 . 1.22 1.28 . 1.26 1.20 . 0.70 . 1

. 0.69 . 1.18 . 1.27 . 1.30 . 1.k2 . 1.14 . 1.70 , 1.17 . 1.23 '1.29 . 1.28 . 1.21 . 0.71 . 10

. -1,6 . =1.6 . 0.5 . $

1.6 . 0.4 -2.0 . 0.3 . 0.6 . 0.8 . 0.4 . 1.3 . 1.0 . 2.0 .

. 0.41 6:4F: 0.896:iiTi:ir.

. 1.P0 . 1.25 i:m:. 1.27i:ir.

, 1.09 i:iiTi:ir: i:ii : i:ir: i:54Ti:ir:6:ir:6:46:

1.21 . 1.10 , 1.29 . 1.25 . 1.21 . 0.89 . 0.41 11

. 2.1 . 2.1 1.7 . 1.0 . -0.8 . -1.7 . -1.7 . -0.3 . 0.6 . 1.1 . '2.4 2.4 3.2 .

3 .... ......... ...............................................o............................

. 0.38 . 0.84 . 1.18 . 1.26 1.26 . 1.P6 . 1,26 . 1.26 . 1.18 . 0.84 . 0.38 .

. 0.40 . 0.87 . 1.19 . 1.26 . 1.24 . 1.24 1.24 1.26 . 1.19 . 0.87 . 0.39 . 12

. S . 8 .. 3.5 . 1.0 . -0.3 . -1.6 . -1.6 . -1.1 . -0.0 . 0.5 . 2.9 . 3.7 .

................................. 1.20 , 1.25 ............................................

. 1.24

. 0.38 . 0.87 1.25 . 1.20 . 0.87. 0.38 0.39 . 0.88 , 1.20 . 1.23 . 1.23 . 1.24 . 1.19 . 0.87 . 0.39 . 13 3.8 . 1.7 . 0.1 . -1.6 . -0.8 . -0.7 . -0.4 I 0.2 . 3.6 .

"~" Tar: 6:m: i:ir: ar: i:ir: 6:m: 6 46u " -

iN : 'i?! : 'i'i : '6?! . '6'i  : ?6?? : ?d :

. STANDARD . . 0.34 . 0.47 . 0.34 . AvtRACE .

. DEVIAff0N . . 0.35 . 0.48 . 0.34 .PC7 OlfftRENCE. ] '

. =0.939 . . 3.7 . 2.3 . 0.9 . . = 1.2 .

................ ....o........... .... ................

I 1

SUMMARY

j MAP NO: N1 9 DATE: 1/28/86 POWER: 100%

CONTROL ROD POSITIONS: F-Q(T) = 1.803 QPTR:

D BANK AT 219 STEPS F-DH(N) = 1.M5 NW 0.994 NE 1.000 F(Z) = 1.196 SW 1.000 SE 1.006 F(XY) = 1.533 BURNUP = 378 MWD /MTU A.0 = -3.00(%) i

~

c 1

l l

22

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j l

FIGURE 4.2 NORTH ANNA UNIT 1 - CYCLE 6 ASSEMBLYWISE POWER DISTRIBUTION N1-6-19 R P N M L k J H C F E O C 8 A

. PRE 0lCIED . . 0.33 . 0.46 . 0.33 . . PRE 0lC1E0 .

. MEASURE 0 . . 0.33 . 0.46 . 0.33 . . MEASURED . 1

. PCT OlFFERENCE. . 1.0 . 1.0 . 1.3 . . PCT OtffERENCE.

......p......... . .. ... . ... .. ... ... . ................

. 0.43 . 0.68 . 1.02 . 0.90 . 1.02 . 0.68 . 0.42 . 2

. 3.3 . 1.2 . -0.3 . -0.4 . -0.2 . 1.6 . 2.7 .

• 6 56* 6.*ih* Yi i8**i$55***I!ii*'I!i$*'\le'*685 * .'

• 6

• 5b' 0.40 . 0.8S . 1.17 . 1.14 1.25 . 1.15 . 1.20 , 0.87 . 0.41 . 3

. 0. 5 . 0.1 . -0.9 . -1.0 . -1.2 . =0.6 . 1.2 . 2.1 . 3.9 .

q i

."6:46' "6:44 T i $i6T i:i6 T i:iiT i:ibT i :iiT i:46T

. 0.41 . 0.84 . 1.20.. 1.20 . 1.32 . 1.19 . 1.31 . 1.21

2. 0 .. 0.2 . ~0.3 . -0.2 .. -0.4 *0.5 . -1.2 . 1.0 .

1.23. i :ibT6:44 0.87 . 0.41 T6: 46' .: 4 l

. 1.9 . 2.6 . 3.2 . j

.'6IkI*.**6 85* 'i!i6* *i.ih* *I 55* *I li* *$*.56* 5 55* *5 5$*Ui ihS*$*i6I *6 55* *6 $i*.*

. 0.42 . 0.86 . 1.19 . 1.17 . 1.34 . 1.11 . 1.20 . 1.11 . 1.36 . 1.20 1.22 . 0.87 . 0.42 . S

. 0.8 . 0.8 . -1.4 . -2.1 . -1.2 . 0.1 . 0.0 . =0.1 . 0.8 . 0.4 . 1.2 . 2.5 . 2,5 . A

. 0.67 . 1.18 1.20 . 1.35 . 1.23 . 1.31 . 1.20 . 1.31 1.23 . 1.35 . 1.20 . 1.18 . 0.67

. 0.67 . 1.20 .'t.20 1.33 . 1.23 . 1.33 . 1.22 1.32 . 1.24 1.35 . 1.19 . 1.18 . 0.67 6

. 1.0 . 1.0 . -0.4 . -1.8 . 0.0 . 1.2 . 1.3 . 0.7 . 1.1 . =0.2 . -0.6 . -0.1 . 1.0 ..

. 0.33 . 1.03 . 1.15 . ....................................................................................

1.32 . 1.11 . 1.31 . 1.12 . 1.34 . 1.12 . 1.31 . 1.11 . 1.32 . 1.15 . 1.03 . 0.33 .

. 0.33 . 1.02 . 1.15 . 1.30 . 1.08 1.30 . 1.14 . 1.36 . 1.13 . 1.32 . 1.10 . 1.29 . 1.14 . 1.02 , 0.33 . 7

, 1.2 . =0.6 . *0.5 . -1.3 . -2.1 . -0.6 . 1.1 . 1.3 . 0.6 . 0.8 +0,6 . -2.7 . -1.1 . *0.6 . 0. 6 ..

i$ik*

'656.6hb'$i5i*'I$i6*.*iih' 0.45 . 0.90 . 1.26 . 1.20 1.205$ib'.

. 1.21 1.37 . 5.63 1.05 . i1.34 i$ 5. 1.20 kb 'k. 1.18 ih* 5 66 1.17.' .51.25 ii b$h6

. 0.91 .'6 $5 0.47 8 j

. *2.S'. -0.7 . -0.8 . -0.2 . 0.2 . 0.9 . 2.2 . 2.1 0.4 . 0.3 . *1.6 . -2.7 . 1.1 0.6 . 1.9 . j 0.33 . 1.03 . 1,15 . 1.32 . 1.11

. 1.31 . l.12 1.34 1.12 1.31 4.11 1.32 .. 1.15 . 1.03 . 0.33 . j

. 0.32 1.00 . 1.12 . 1.31 . 1.11 1.30 . 1.09 . 1.33 . 1.12 . 1.31 . 1.10 , 1.31 1.16 . 1.04 . 0.34 . 1

-2.6 -2.6 . -2.6 . -1.1 . 0.4 . =0.8 . -3.3 . -0.6 9 1

-0.1 . -0.4 . =0.5 . =0.9 . 0. 4 . 1.4 . 2.9 .

.. ..................................................... ...............................................n

. 0.67 , 1.18 . 1.20 . 1.35 . 1.23 . 1.31 . 1. 20 . 1.31 . 1.23 . 1.35 . 1.20 . 1.18 . 0.67 .

. 0.65 . 1.15 . 1.20 1.37 1.23 . 1.28 . 1.19 . 1.30 . 1.23 . 1.35 . 1.21 . 1.20 . 0.69 . 10

. -2.6 . -2.6 . =0.1 . 1.3 . -0.3 . *2.2 . -0.8 . -0.9 . *0.4 . *0,5 . 1.2 . 1.6 . 3.1 . ,

. 0.41 . 0.85 . 1.20 1.19 . 1.35 . 1.11 . 1.20 1.11 1.35 1.19 . 1.20 . 0.85 . 0.41 . 1 0.42 . 0.86 . 1.22 . 1.20 . 1.33 1.08 . 1.17 1.09 . 1 35 . 1.20 1.23 . 0.87 . 0.43 . 11

. 1.2 . 1.2 . 1.0 . 0.7 . -1.9 . -2.4 . 2.3 . -1.h . -0.4 . 0.7 . 2.3 . 2.5 . 3.3 .

"""T6:46T6:44Ti:56Ti:46Ti:iiTi:56Ti:iiTi:i6Ti:56T6:44T6:46T"""

. 0.42 . 0.87 1.21 . 1.18 . 1.29 . l.17 . 1.29 . 1.19 1.20 . 0.87 . 0.41 12 i

. 5.0 4 2.9 . 0. 7 .

• 1. 3 . *2. 5 . -2. 5 . -2. 3 . -1. 2 . -0. 3 . 2.7 . 3.4 .

. 1

• • i

• • • • • • 6*$6* *6 i$*.*i'iE*.**i ih*.**i ii'.*i i$* *i.55*.**6*85*;*6 56* "*****

. 0.413.5 .

. 0.87 . 1.18 . 1.12 . 1.24 . 1.13 . 1.16 . 0.85 . 0.41 . 13

. 1.9 . -0.6 . -3.3 . 2.4 . -2.2 . -1.8 . -0.5 . 3.3 .

" " " T 6:4i T 6: &iT i:6i' : '6: h6T i:6iT 6:4iT 6: 41 T " " "

. 0.42 . 0.69 . 1.03 . 0.90 . 1.01 . 0.66 . 0.40 14

. 1.9 . 2.7 . 0.1 . *0.2 . 2.1 . *1.7 . =3.0 .

, STANDARD . 0.33 . 0.46 . 0.33 . . AVERACE .

. OEvtAtt0N . . 0.34 . 0.47 . 0.33 . . PCT DIFFERENCE. i

. *1.013 . . 3.4 1.6 . -0.4 . . = 1.4 .

SUMMARY

MAP NO: N1-6 19 DATE: 10/ 7/86 . POWER: 96%'

CONTROL ROD POSITIONS: F-Q(T) = 1.775 QPTR:

D BANK AT 228 STEPS F-DH(M) = 1.416 NW 0.996 NE 1.007 l F(Z) = 1.149 SW 0.997 SE 1.000 i

F( XY) = 1.552 BURNUP = 8170 MWD /MTU 'A.0 = -4.00(%)

I 23 m

(

i l

l I

FICiLJFIE 4.3 NORTH ANNA UNIT 1 - CYCLE 6 I ASSEMBLYWISE POWER DISTRIBUTION N1-6-33 R P N M L M J H 0 F E D C 8 A (

i

' ' AAi616ii6":

MEASURED .

.'6:it':'6:ii'.'6:ii'.

0.37 . 0.52 . 0.38 .

"kAi616ti6":

. MEASURED 1

. PCT DIFFERENCE. . -0.1 . -0.1 . 0.6 . PCT OlFFERENCE..

6$k6$bhi.'i6k 6hi.ib4 b$ii'. 6 E6

. 0.47 0.72 . 1.04 . 0.93 1.04 . 0.72 . 0.47 . 2

. 2.2 . 1.7 . 0.0 . -0.0 . -0.1 . 1.4 . 2.2 .

3

. 0.45 . 0.88 . 1.19 . ).13 . 1.28 . 1.13 . 1.19 . 0.88 . 0.45 .

. 0.45 . 0.89 . 1.20 . 1.13 . 1.28 . 1.14 . 1.21 . 0.90 . 0.46 . 3

. 0.8 . 0.6 0.5 . ~0.1 . -0.3 . 0.2 , 1.6 . 2.1 . 3.0 .

. 0.45 . 0.88 . 1.20 . 1.16 . 1.31 1.17 . 1.31 . 1.16 . 1.20 . 0.88 . 0.45 .

. 0.45 . 0.88 . 1.21 . 1.17 . 1.32 . 1.17 , 1.31 . 1.18 . 1.23 . 0.90 . 0.45 . 4

. 1.5 . 0.6 . 0.3 . 0.6 0.3 . 0.2 . -0.2 . 1.8 . 2.2 . 2.5 2. 0 .

. 0.46 . 0.88 . 1.20 . 1.15 . 1.31 . 1.08 . 1.15 1.08 . 1.31 . 1.15 1.20 . 0.88 . 0.46 .

. 0.47 0.89 . 1.20 . 1.14 . 1.31 . 1.09 . 1.16 . 1.09 . 1.33 . 1.16 . 1.23 . 0.89 0.47 . 5

. 0.9 . 0.9 . -0.4 . -0.8 . -0.2 . 0.5 . 0.4 . 0.5 . 1.4 . 1.5 . 1.9 . 1.0 . 1.0 .

. 0.71 . 1.19 . 1.16 . 1.31 . 1.18 1.29 . 1.15 . 1.29 . 1.18 . 1.31 . 1.16 . 1.19 . 0.71 .

. 0.71 . 1.21 . 1.16 1.30 1.19 . 1.31 . 1.17 1.39 . 1.19 . 1.31 . 1.16 . 1.18 . 0.71 . 6 -

. 1.1 . 1.1 . 0.1 . -0.9 . 0.5 1.5 . 1.5 . 0.9 . 1.4 . -0.0 . -0.5 . -0.9 . 1.0 .

. '6:ii':'i:64':"i:ii':'i:ii'",1.06

. 0.38 . 1.04 . 1.13 . 1.30 .i:64':'i:56'.'i:66':'i:ii':'i:66'.'i:56':'i:66':'i:ii':'i:ii':'i:64*:*6:ii':

1.29 . 1.11'. 1.31 . 1.10 . 1.30 . 1.07 . 1.27 , 1.11 . 1.03 . 0.37 . 7 j l

. 1.2 -0.4 -0.3 . -1.1 . -1.8 . =0.4 . 1.4 . 1.5 . 0.7 . 0.7 . -0.9 . -3.1 . -2.0 . 1.4 . 0.6 . )

........................................................ ............................................... . 1

. 0.52 . 0.93 . 1.28 . 1.17 . 1.15 . 1.15 . 1.29 . 1.00 . 1,29 . 1.15 . 1.15 . 1.17 . 1.28 . 0.93 . 0.52 .

. 0.51 . 0.93 . 1.27 . 1.16 . 1.15 . 1.16 . 1.32 . 1.02 1.30 . 1.15 . 1.14 . 1.13 . 1.25 . 0.92 . 0.52 . 8

. -2.0 . -0.5 . -0.5 . -0.5 . -0.5 . 0.5 . 2.4 . 1.9 . 0. 3 . 0.2 . -1.6 . -3.1 . -2.0 . -1.3 . 0.6 .

0.37 1.04 . 1.13 . 1.31 1.08 . 1.29 . 1.09 . 1.29 , 1.09 , 1.29 . 1.08 . 1.31 . 1.13 . 1.04 . 0.37 .

. 0.37 1.02 . 1.11 1.30 . 1.08 . 1.28 , 1.06 . 1.29 . 1.09 . 1.29 . 1.08 . 1.30 . 1.13 . 1.03 . 0.38 . 9

. -2.0 . 2.0 -2.0 -0.9 . -0.3 . -1.0 . -2.4 . -0.4 . -0.1 . -0.3 . ~0.4 . -1.2 . -0.2 . -0.5 . 0.9 .

. 0.71 . 1.19 . 1.16 . 1.31 . 1.18 . 1.29 . 1.15 . 1.29 . 1.18 . 1.31 1.16 . 1.19 . 0.71 .

. 0.69 . 1.17 . 1.17 1,32 . 1.17 . 1.27 1.14 1.28 . 1.18 . 1.31 . 1.17 . 1.21 . 0.71 . 10

> . -2.0 . -2.0 . 0.6 . 0.6 . =0.4 . -1.9 . -0.8 . -0.7 . -0.2 . -0.3 . 1.0 . 1.1 . 1.3 .

. '6: 4& ' :

• 6:ii' : ' i:i6' : 'i: is' " i: ii' : ' i: 66' . ' i: ii' :

• i:66':

• i:ii' : ' i : ii': ' i:i6': '6: 66' :

• 6: 4i' :

0.48 . 0.92 . 1.23 . 1.15 , 1.29 . 1.06 . 1.13 . 1.07 . 1.31 . 1.15 . 1.22 . 0.90 . 0.47 . 11

. 3.8 . 3.8 . 1.9 . 0.1 . -1.6 . -2.1 . -2.1 . -1.4 . -0.3 . 0.3 . 1.3 . 1.4 1.9 .

" " " ' : '6: si' : ' 6 :ii' :

• i:i6' : ' i' ii' :

• i:ii' : 'i: ii' :' i:ii ': 'i: i& * :

• i:i6' : ~ 6:ii' :

• 6: 46' :'" ' " '

. 0.46 . 0.90 . 1.21 . 1.15 . 1.28 . 1.14 . 1.28 . 1.15 1.20 . 0.89 . 0.45 . 12

. 3.8 . 2.0 . 0.1 . -1.3 . 2.6 . -2.6 . -2.2 . -0.9 . -0.4 1.4 . 1.7 .

. 0.45 . 0.88 . 1.19 . 1.13 1.28 , 1.13 . 1.19 0.88 . 0.45 .

. 0.45 . 0.89 . 1.18 . 1.10 . 1.25 . 1.11 . 1.17 . 0.88 . 0.45 . 13

) 2.0 0.2 . -1.3 . -3.3 . -2.7 -2.4 . -1.7 . -0.9 . 1.6 .

" * "' ' : ~ 6: 4& ' ' '6:ii':' i:64 * : '6: 6i' : 'i:64 ' :"6:ii' : '6:4&' : " " "'

. 0.46 . 0.71 . 1.03 . 0.92 . 1.02 . 0.69 . 0.45 . 14

. 0.2 . 0.6 . -1.4 . -1.4 . -2.3 . -1.7 . -2.2 g... .

...g.g .......... ..... .....;ggg;gg....

. DEVIATION . 0.38 . 0.52 . 0.37 . . PCT DI F FERENCE.

. =0.866 . . 1.0 . -0.1 . -1.2 . . = 1.2 .

SUMMARY

MAP NO: N1-6-33 DATE: 4/14/87 POWER: 87%

CONTROL ROD POSITIONS: F-Q(T) = 1.705 QPTR:

D BANK AT 228 STEPS F-DH(M) = 1.360 NW 1.001 l NE 1.007

...........j..........

F(Z) = 1.156 SW 0.999 i SE 0.993 F(XY) = 1.486 BURNUP = 15532 MWD /MTU A.0 = + 3. 38( %)

24

FIGURE 4.4 HOT CHANNEL FACTOR NORMAllZED OPERATING ENVELOPE 12 (6.00, 1.00) 1.0  % (10.91, 0.94)

~

K n

Z 0.8 \

\

N O

R M

A06

• L 1

Z E

F (12.00, 0.45)

)

0 m

0.4 Z

0.2 0.0- 4 0 2 4 6 8 10 12 CORE HEIGHT tFT1 BOTTOM TOP 25

l 1

3 i

i i

1 i

i FIGURE 4.5 s NORTH ANNA UNIT 1 - CYCLE 6  !

HEAT FLUX HOT CHANNEL FACTOR, F[(Z) )

N1-6-09 e.3 +

e R

I h

e.0 +

l H CY N

• 4

\

I MMMM g *

=

MMMM MM XM XMMMMMX )

C MM b

M M MMMMM M XM o =

M M M i.. .

. x x M M M

M M

. M a M, a

ta

M a M M

• l i

• M U MM 1.0 +

M b

• e

-  :=

= M g - M #

a -

e  : x 0.5 +

) s -

M l

g  :

=.  :

0.0

• BOTTOM Of CORE TOP OF CORE AXIAL POSIT 0N (NODES) l 26

I- l 1  :

l l

1 NORTH ANNA UNIT 1 - CYCLE 6 HEAT FLUX HOT CHANNEL FACTOR, F (Z)

N1-6-19 )

2.

2 s

2.0 v

sNcx  : ,

• xxxxx l, e - xxx xx xxxxx

• M XX = x xxxxxxx xxxx Q ,

x s

U ... .

x x x x x x x xxx x

N x x x x x

J  : x W . x

. x <

ex x x j

\

1.0 + x j U

• H = x x 1

) D

• Y O'9 ,*

v b

=

0.0 + l j

50 5' O' 5' 30' 25' 20' 15' O'

TOP OF CORE AXIAL POSITION (NODES) 27 l

I.

? FIGURE 4.7 l NORTH ANNA UNIT 1 - CYCLE 6 HEAT FLUX HOT CHANNEL FACTOR, F (Z) l N1-6-33 2.5 +

)

I

. I'

) =

• 4

=  !

a n

h v

2.0 +

x -

O b

U 1.5 + MM

< - MM MM .

• MMMMMMM M M i

• M MM MMMMMM M j

= MM MM M MMMM MMMMMMM M MM M

= M M M M

- M M M X

-M M

. X

_ . . x U 1.0 + .

• M M l b = 1 O - M

= -

• M X

• O -

d  :

0.5 +

H* -

<d r.

0.0 +

BOTTOM OF CORE TOP OF CORE AXIAL POSITION (NODES) i 28

FIGURE 4.8 NORTH ANNA UNIT 1 - CYCLE 6 MAXIMUM HEAT FLUX HOT CHANNEL FACTOR, Fg *P, VS.

AXIAL POSITION 2.4 2.2 -

2.0

.. . . ..... 1 i.e

,,, .- ., , . . ....., g at .

, Jt - JL .

i .e . .

+ .. g i.4

\

F . .,< k

, 1. 2 \

e .

1.0 ~)

e 0.8 0.6 04 02 0.0 -

4' Si 55 50 45 40 35 30 25 20 15 10 5 i RX1AL POSIT 10N fNODE1 BOTTOM OF CORE TOP OF CORE 29

{ FIGURE 4.9 l

l NORTH ANNA UNIT 1 - CYCLE 6 MAXIMUM HEAT FLUX HOT CHANNEL FACTOR, F (Z), VS. BURNUP n

2.4 2.3 M

R g ,g X

1 M

U 2.1 M

H l2.0 T

[1.9 U .

X 18

• x x x x K x T '-

x x C

I '7 H .

A '

N N 1.6 E

L F 1.5 A -

C 1

0 I4 R

1.3 I'2', .. ., .... , .. .... .... .. .... .... . . .... . .. .. . .... .. . .. .

0 2000 4000 6000 8000 10000 12000 14000 16000 CYCLE BURNUP (MWO/MTU) 30

FIGURE 4.10 l

NORTH ANNA UNIT 1 - CYCLE 6 MAXIMUM ENTHALPY RISE HOT CHANNEL FACTOR, F-DELTA H, VS.

BURNUP 1.60 1.55 E

, N 1.50 3 ._

H v A x ^

l X p 1.45 x x Y X R *

X X V

S 1 40 E

• x H >:

0

• y 1.35 C

H 1.30 N

E L

1.25 A

C T

0 1.20 R

1.15 1 10 ,, . .. . ,, , , , .., , , .. . .. ... ., . ,, , . . . . .

0 2000 4000 6000 6000 10000 12000 14000 16000 CYCLE BURNUP (MWD /MTU) 31

_ _ _ _ _ _ _ _ _ _ _ _ _ , - ----- __ "~

FIGURE 4.11 NORTH ANNA UNIT 1 - CYCLE 6 TARGET DELTA FLUX VS. BURNUP 10 1

i l 6 1

6 T

R R

G 4 E

i 3 D

E 2

L T

R 0

L 0

X y a N -2 L

P ~

~

~

E g a a C -4 a a '

E a a t

a

-6

-6

-10 ,, ,

0 2000 4000 6000 8000 10000 12000 14000 16000 CYCLE BURNUP (MWD /MTU) 32

FIGURE 4.12 NORTH ANNA UNIT 1 - CYCLE 6 CORE AVERAGE AXlAL POWER DISTRIBUTION N1-6-09 1.5 + F Z

= 1.196

[- AXIAL OFFSET = -3.00 1.2 + MMMMM M

=

MMMM M j' M MMM MM M M M M MMMM M

MM

= M MM M M

^ = M MM MMM A . M LLI . M M M N = M M N 0.9 +

4 . M M k = M M C)

• Z

', e MM v a M M

g 0.6 .+ M M

=

g .

X

."M M

=

M 0.3 .+. M 0.0

• 61 SS' 50' 5' * '

0' 35' 30 5' 0' 15' BOTTOM OF CORE 10' S TOP OF COR[

AXIAL POSITION (NODES) 33

FIGURE 4.13 NORTH ANNA UNIT 1 - CYCLE 6 CORE AVERAGE AXIAL POWER DISTRIBUTION N 1 19

,,3 F7 = 1. M

AXIAL OFFSET = -4.00 1.2 .+

• MMMMXM

=

MMM M MMMMM K M A

M x xxxxgg xxxg M

Q * # X M M MMK w -

x M M M M bJ , X x K

X

] 0.9 + "

$ - M ta  : ",,

o .

5  : " x x

0.6 +

m .

N . X x v .x A .

. MM 0.3 +

0.0 +

6 O' S'

• 0* *l5' *

• 30' S' 0*

15' 10 t

TOP OF CORE AXIAL POSITION (NODES) 1 34

FIGURE 4.14 NORTH ANNA UNIT 1 - CYCLE 6 CORE AVERAGE AXIAL POWER DISTRIBUTION N1-6-33 1

F = 1.156 7

AXIAL OFFSET = +3.38 1.2 +

MM

• MM MM MMM l

m XX X MMMXXX XXMxxx x l p - x x x x W

• x x x x M x h

a 0.9 + x x

x e

0.6 + X A .

N . M v .

N

• N

• e 0.3 .+

0.0 +

0' **

• $$' ts**ho* ****ln** TOP S' $0' $0

• n, 9 1s *h* ,

OF CORE AXIAL POSITION (NODES) 35

Figure 4.15 NORTH ANNA UNIT 1 - CYCLE 6 CORE AVERAGE AXIAL PEAKING FACTOR vs. BURNUP 1

1. 4 l

l l

l 1.3 A

X 1

p ...-

L P

E R

1 1.2 a N A G

a F 4 A 3 3 a 3 3 j, 3 4 C a -

3 T

0 -

R .

1 ,

11 10,. . . . ,,, . ,, ,

..=,, . ,... .. , , ,. . .. ..,

0 2000 4000 6000 8000 10000 12000 14000 16000 CYCLE BURNUP (MHD/MTU) 36

Section 5

\

PRIMARY COOLANT ACTIVITY FOLLOW l

Activity levels of iodine-131 and 133 in the primary coolant are important in core performance follow analysis because they a e used as indicators of defective fuel. Ar'ditionally, they are important with respect to the offsite dose calculation values associated with accident analyses. Both I-131 and I-133 can leak into the primary coolant system through a breach in the cladding. As indicated in the North Anna 1 Technical Specifications, the dose equivalent I-]31 concentration in the primary coolant was limited to 1.0 pCi/gm for normal steady state operation. Figure 5.1 shows the dose equivalent I-131 activity level history for the North Anna 1, Cycle 6 core. The demineralized flow rate averaged 77.5 gpm during power operation. The data shows that during Cycle 6, the core operated substantially below the 1.0 pCi/gm limit during steady state operation. Specifically, the average dose equivalent I-131

-2 concentration of 3.1 x 10 pCi/gm is equal to approximately 3*; of the Technical Specifications limit.

During most of Cycle 6, the core operated with one leaking fuel rod that was carried over from Cycle 5. At the end of. cycle 6, another defect formation event apparently occurred as indicated by the increased coolant activity level during March and April. During the post-irradiation ultrasonic fuel examination, a second failed fuel rod was found. Both fuel assemblies containing these two failed rods were discharged from the core and suitable replacements have been found for Cycle 7.

37

The ratio of the specific activities of I-131 to I-133 is used to characterize the type of fuel failure which may have occurred in the reactor core. Use of the ratio for this determination is feasible because I

\

I-133 has a short half-life (approximately 21 hours2.430556e-4 days <br />0.00583 hours <br />3.472222e-5 weeks <br />7.9905e-6 months <br />) compared to that of i I-131 (approximately eight days). For pinhole defects, where the diffusion time through the defect is on the order of days, the I-133 decays leaving the I-131 dominant in activity, thereby causing the ratio to be 0.5 or more. In the case of large leaks and " tramp"* material, where the diffusion mechanism is negligible, the I-131/I-133 ratio will generally be less than 0.1. Figure 5.2 shows the I-131/I-133 ratio data for the North Anna 1, Cycle 6 core at a general average value of 0.12.

• " Tramp" consists of fissionable material as an impurity in the reactor core materials or fissionable material which has adhered to the surface of reactor core components.

38

NORTH ANNA UNIT 1 CYCLE 6 DOSE EQUIVALENT I-131

, TEChN1 CAL SPECIF}cpTIONS LIMIT

,, o

~_ o t

_ o

- o O

g O

0 0 0

'a

- e M .

O e

• o 8 e O O o e y e O

EQ 0- m  ?  ?

8 0 N -

o e O 53 0

-0 e

- _ e m _ o O O O o -

e O O m -

om 0

~b e o I- - O Q

_ O O

O e

O gO a

~- m $O o

o O O

- .100

/

b I 5 y , _

5

- 8 50 cc tu O

b j $

~ ll i i g '

l

' i ,

0 JAN FEB Man APR hay JUN JUL AUG SEP OCT Ney OEC' JAN' FE8I NARi APF.

4 ,

1986 1967

,n

Figure 5.2 NORTH ANNA UNIT 1 CYCLE 6 I-131/ I-133 ACTI VI TY R AT I O vs. TIME o

e o 0 o

O l O C

1 Ho l C l C C-Wo r o

l > o'

- o w

(J g C O mm

- 0 0 0 o @

s g o ,

mm o ,c o m O

}

~

Cq ?

o 9 o S d

8

-n $ MSsmo- p

-+56% Gy =' -f ~pps -

fT ""Q -

hhNY

"'f O

8 5

ei 200

[ 1 y y _

-50 e it

\l i i i .JO i i i i i i i i i i i JAN FEB HAR APR MAY JUN JUL RUG SEP OCT NOV DEC JRN FEB Nrh APR 1986 '

1987

_________ _ 40

Section 6 CONCLUSIONS Throughout Cycle 6 of North Anna Unit 1, the core performance indicators compared favorably with the design predictions and the core related Technical Specifications limits were met with significant margin. No significant abnormalities in reactivity or burnup accumulation were detected. In addition, the mechanical integrity of the fuel did not change significantly throughout Cycle 6 as indicated by the radiciodine analysis.

41

Section 7 REFERENCES J

1) C. A. Ford and J. V. Iannucci, " North Anna Unit 1, Cycle 6 Startup Physics Test Report," VEP-NOS-21, February 1986.

2) North Anna Power Station Unit 1 Technical Specifications, Sections 3/4.1 and 3/4.2.

3) T. K. Ross, "NEWTOTE Code", VEPCO NFO-CCR-6 , Rev. 8, April, 1984.

4) R. D. Klatt, W. D. Leggett, III, and L. D. Eisenhart,

" FOLLOW Code," WCAP-7482, February, 1970.

5) W. D. Leggett, III and L. D. Eisenhart, "INCORE Code,"

WCAP-7149, December, 1967.

42

_ _ - _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ .