ML20074A016
| ML20074A016 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 05/02/1983 |
| From: | Kunishi H, Pritchett P, Roberts E WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| To: | |
| Shared Package | |
| ML20074A014 | List: |
| References | |
| WCAP-10252, NUDOCS 8305110398 | |
| Download: ML20074A016 (66) | |
Text
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l WESTINGHOUSE PROPRIETARY CLASS 3 Di
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i SECOND CYCLE PERFORMANCE OF BEAVER VALLEY UNIT 1 FUEL
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By 3
P. A. Pritchett !
H. Kunishi j Approved:
E. Roberts, Manager Irradiation Testing i Westinghouse Electric Corporation Nuclear Energy Systems P. O. Box 355 Pittsburgh, Pennsylvania 15230 8305110398 830502' PDR ADOCK 05000334 PDR p _
WESTINGHOUSE PROPRIETARY CLASS 3 Table of Contents Section Title Page 1 Introduction 1-1 2 Beaver Valley Unit 1 Fuel Design 2-1 3 Beaver Valley Unit 1 Second Cycle Operating History 3-1 4 Fuel Examination 4-1 4.1 Binocular Examination 4-1 4.2 Television Examination 4-5 4.2.1 Fuel Rod Surface Condition 4-5 4.2.2 Peripheral Fuel Rod Channel Closure 4-6 4.2.3 Peripheral Fuel Rod-to-Nozzle Gap 4-11 and Rod Growth 4.2.4 Examination of Fuel Assemblies at 4-27 Baffle Joint 5 Conclusion 5-1 6 References 6-1 1
Appendix A iii 0239L:6
WESTINGHOUSE PROPRIETARY CLASS 3 List of Illustrations Jigure Title Page 3-1 Cycle 2 Power History 3-4 3-2 Cycle 2 Moderator Temperature History 3-5 3-3 Cycle 2 Core Loading Pattern 3-6 3-4 Cycle 2 Coolant Activity 3-7 3-5 Boron Versus Lithium Concentration in DLW's 3-8 Reactor Coolant During Cycle 1 and Cycle 2 4-1 Surface Condition of Peripheral Fuel Rods in Beaver 4-7 Valley Fuel Assembly C49. Left Side EOC-1 and E0C-2 4-2 Maximum Channel Closure [ ] Percent Assembly B13, 4-13 (b,c)
Face 4, Span 4 Rods 10 and 11 4-3 EOC-2 Axial Variatics in 95th Percentile 4-14 Fuel Rod Channel Closure in Beaver Valley Unit 1 4-4 Worst-Span Channel Closure Behavior at the 4-15 95th Percentile Level 4-5 EOC-2 Distribution of Peripheral Fuel Rod-to-Nozzle 4-17 Gaps (Bottom Gap plus Top Gap) in Beaver Valley 4-6 Face-to-Face Variation of Rod-te-Nozzle Gap in Fuel 4-18 Assembly B13 af ter Two Cycles of Operation 4-7 Typical Rod-to-Nczzle Gaps at EOC-1 and EOC-2 4-20 (Assembly B13, Face 2, Left Sice) 4-8 Top and Bottom Gap of Assembly B04 Left Side 4-21 Face 1, EOC-1, and EOC-2 4-9 Bottom Gap Change Versus Burnup 4-24 4-10 Top Gap Change Versus Burnup 4-25 4-11 Fuel Rod Growth Variation with Fluence 4-26 4-12 Location of Fuel Assemblies Examined for effects of 4-29 Coolant Cross Flow Through Baffle Joints 4-13 Example of White Clean Mark on Grid 6 on Face 3 of 4-33 Assembly D41 j 4-14 Assembly D36 Face 3 (Rod 12 Exhibits Downward 4-34 Slippage) v 0239L:6
WESTINGHOUSE PROPRIETARY CLASS 3 i
1
~
List of Illustrations (continued) i Figure Title Page
]
4-15a Illustration of Mechanism of Channel Closure Due to 4-35 Bernoulli Effect 4-15 Detectable Reduction in Channel Between Rods 4-36 15 and 16 at Midspan Between Grids 1 and 2 on Face 1 of D24 j
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WESTINGHOUSE PROPRIETARY CLASS 3 l
i List of Tables i Table Title Page
- . 2-1 Core Design and Operating Characteristics 2-2 3-1 Power and Burnup History Summary for Beavar Valley 3-3
- Unit 1 4-1 Beaver Valley E0C-2 Binocular Examination of 4-2 l Assemblies 4-2 Beaver Valley Unit 1 Planned EOC-2 T. V. Visual 4*3 Examination 4-3 Beaver Valley Unit Unplanned EOC-2 Examination 4-4 4-4 Fuel Rod Channel Closures > [ ] percent in Beaver 4-12 (b,c)
Valley Unit 1 Fuel at E0C-2 I 4-5 Beaver Valley E0C-2 Rod-to-Nozzle Gap and Rod Growth 4-23 f 4-6 Beaver Valley EOC-2 High Mag T. V. Visual of Baffle 4-30
- Assemblies 1
4-7 Assemblies Exhibiting Clean White Mark on Grids 4-32 a
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) vii 0239L:6 4
I .
i WEST!NGHOUSE PROPRIETARY CLASS 3 ;
i 4
1.0 INTRODUCTION
i I i
The 17x17 fuel assembly is in extensive operation in recent Westing-
{
house 3-loop and 4-loop reactors with power up to 3800 MWT and average l
{ linear power of 5.4 kw/ft. This design extends fuel capability beyond !
j that of the 15x15 design in use to date in reactors of this size. It l l was adopted primarily in response to the ' lowered average kw/ft require- !
ments imposed by the AEC Interim Acceptance Criteria. While the primary intent of the design is to reduce stored energy in fuel rods for LOCA l conditions, it is also expected that rod bow will be decreased because
- of the shorter grid span lengths characteristic of the 17x17 design.
l The NRC has required fuel surveillance inspections on the first several 17x17 plants to go into operation, including Beaver Valley Unit 1, to verify satisfactory fuel performance. ,
, l j The purpose of the Beaver Valley fuel examination was to evaluate the j mechanical integrity of fuel rods and fuel assembly structural compo-nents, fuel surface condition, rod-to-nozzle gap and fuel rod bow; and f - to compare the Beaver Valley fuel performance with that of other 17x17 ,
, fuels.
l Beaver Valley completed cycle 1 in November, 1979. Thirty-five fuel assemblies were non-destructively examined with underwater television and a large number of assemblies were binocular examined. The visual l examination showed the assemblies to be in excellent mechanical
! condition.(1) I Cycle 2 of Beaver Valle/ Unit I was completed in December, 1981. One hundred fifty-three (153) fuel assemblies were binocular examined and thirty (30) fuel assemblies were T.V. visually examined with underwater i television consistent with the planned program. Of the thirty fuel assemblies. ten fuel assemblies.were selected as representative fuel assemblies from Regions 2 and 3 and the remaining twenty fuel assem-blies were examined for possible effects of coolant cross flow through i baffle joints. In addition, several assemblies, supplementary to the
- planned program were examined due to fuel handling problems. ;
1-1 0239L:6
WESTZNGHOUSE PROPRIETARY CLASS 3 2.0 BEAVER VALLEY UNIT 1 FUEL DESIGN Duquesne Light, Beaver Valley Unit 1 is a 3-loop 17x17 reactor with 2652 MW thermal power rating. The fuel in Beaver Valley Unit 1 is of the low 8
parasitic design. Each of the 157 fuel assemblies in the reactor core l l contains 264 Zircaloy-4 clad fuel rods. Each rod is approximately thirteen feet long and contains a twelve-foot long column of fuel pel-i lets. Spacing between the fuel rods is maintained by eight Inconel 718 i alloy grids nearly equally spaced along the length of the fuel rods. In each fuel assembly, the top and bottom nozzles and the eight grids are attached to twenty-four Zircaloy-4 thimble tubes which extend between the n'ozzles and through thG eight grids. In the Region 4 fuel, pellet
! density was 95 percent of theoretical density, and the fuel rods were
- prepressurized with helium to [ ] psig. In Table 2-1, several Beaver (a,c)
Valley Unit I core design and operating characteristics are compared j with those of Salem Unit 1 (Public Service Electric and Gas Co.), Salem Unit 2 (Public Service Electric and Gas Co.), and Trojan (Portland i
General Electric Company) reactors.
While physical dimensions of the Beaver Valley Unit 1 fuel are the same ,
l as in the standard 17x17 design in the Salem Unit 1, Salem Unit 2 and i 4
Trojan reactors the nuclear and thermal characteristics are not iden-tical. Core average linear power is lower in Beaver Vality than Trojan -
and both Salem Units.
8 1
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2-1 0239L:6 i i
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WESTfNGHOUSE PROPRIETARY CLASS 3 TABLE 2-1 CORE DESIGN AND OPERATING CHARACTERISTICS U02 Enrichment w/o U-235 (a,c)
Region 1 Region 2 Region 3 Region 4 Coolant Temperature Hot Zero Power, F Initial Inlet Initial Core Ave.
HFP, F Operating Coolant Pressure, psig Average Linear Power kw/ft 2-2 0239L:6
WESTINGHOUSE PROPRIETARY CLASS 3 1
i f 3.0 BEAVER VALLEY UNIT 1 SECOND CYCLE OPERATING HISTORY Beaver Valley Unit 1 achieved criticality in the second cycle in November, 1980 and completed the second cycle in December, 1981 with Cycle 2 average burnup of 9,640 MWD /MTU. A brief summary of region burnup and powers is given in Table 3-1.(2) 1 Reactor power history and temperature history are plotted in figures 3-1 and 3-2. The Cycle 2 core loading pattern is shown in figure 5-3.
The activity of the fission products I-131 and I-133 in the primary coolant was measured during Cycle 2 to monitor the defect condition of the fuel. Iodine activity is an important indicator of fuel integrity.
Although there is no quantitative correlation of activity with the number of fuel rod defects, because large defects release more activity than small defects and because reactor power transients cause sudden transient activity increases or spikes, activity levels in a general sense reflect the condition of the fuel. The I-131/I-133 activity ratio is an indicator of the type of defect. A low I-131/I-133, ratio results from an open fuel rod defect, one which allows rapid release into the coolant of both the longer half life I-131 and the shorter half life I-133. A closed defect restricts release of iodine from the fuel rod and since the short-lived I-133 decays to its daughter Xe 133 more rapidly than does the I-131 the ratio of I-131 to I-133 in the coolant is higher. A ratio of 0.1 to 0.3 indicates rapid release through an open defect and a ratio greater 0.5 indicates delay of iocine release through a tight defect. Figure 3-4 shows the activity in the coolant 4 during Cycle 2. All iodine measurements reported Fere were made at or near full power thus avoiding transients or spikes associated with increasing or decreasing power. At the beginning of Cycle 2, iodine activity was similar to that at the end of Cycle 1. During Cycle 2, the activity remained constant until near the end of Cycle 2 where a small increase in the iodine levels appears to have occurred. Some scatter in the data exists, however, the I-131/I-133 activity ratio also apoears to
! have decreased late in the cycle, indicating the possibility of an open 3-1 ,
0239L:6
WESTINGHOUSE PROPRTETARY CLASS 3 i ;
I type defect. The coolant iodine activity remained less than 5 percent of the technical specification limit (1p Ci/ml of I-131) for most of I the Cycle 2, typcial of a low-defect core.
Figure 3-5 shows boron-lithium concentration for Cycles 1 and 2. Beaver l Valley operated in a crud dissolving mode for both cycles. The critical solubility curve of figure 3-5 represents the dividing line between crud precipitating and crud dissolution based on the crud transportation
- processes developed by Westinghouse.(3) Below the solubility curve, i there is a tendency for magnetite precipitation on hotter surfaces, assuming a saturated solution. Above the curve, the solubility of magnetite increases with temperature, thus there should be a tendency to dissolve the material from the core surface, or at least retard the precipitation.(4) 1 J
i f
3-2
. 0239L:6
WEST!NGHOUSE PROPRIETARY CLASS 3 TABLE 3-1 POWER AND BURNUP HISTORY
SUMMARY
FOR BEAVER VALLEY UNIT 1 Cycle 1 Cycle 2 Average Power Burnup Average Power Burnup Region kw/ft) (MdD/MTU) (kw/ft) _ (KdD/MTU) 1 (a,c) 2 3
4 4A 3-3 0239L:6
24852 WESTINGHOUSE PROPRIETARY CLASS 3 1
2800
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r g- y) e 2400 q @
2000 h.
5 l E
g 1600 - - -
B a
y 1200 L n
2 800 -
400 -
0 O 50 100 150 200 250 300 350 400 TIME (days since first data point)
Figure 3-1. Cycle 2 Power History 3-4
WESTINGHOUSE PROPRIETARY CLASS 3 24853 600 590 -
C 580 -
570 E
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n S 1
$ 560 l t
3 550 - ,
o 540 -
a 6 530 -
O C
2 520 -
510 -
I ! !
500 O 50 100 150 200 250 300 350 400 TIME (days since first data point)
Figure 3-2. Cycle 2 Moderator Temperature History 3-5 l
i
2m WESTINGHOUSE PROPRIETARY CLASS 3
, 180*
R P N M L K J H G F E D C 8 A D03 D19 D22 3
D35 D38 002 543 047 DOS D31 H-7 2 D32 D27 861 816 824 818 833 D29 D18 J4 E-5 H3 G4 3 F5 D21 C32 800 C40 C13 C22 C44 C52 831 C06 D01 J1 J6 J2 L2 H1 E2 G2 G4 G1
- D35 D16 SOS *C49 815 C15 838 C47 837 C14 847 011 D43 5 K7 A -9 L4 L3 M4 E3 E4 R9 F7 D41 805 C04 807 C20 817 C36 850 C34 839 C06 812 034 M-7 P7 M-5 N4 K3 K -2 F3 C4 D-6 8-7 D7 6 D50 D33 822 C27 C09 845 C30 C07 C23 802 C18 C51 823 D30 040 y L4 P5 N5 N4 M-3 F2 D-3 C4 C5 8-5 E6 201 835 827 C39 841 C45 C21 A11 C03 C17 803 C41 808 814 ZD2 90* N4 R8 270' J-8 L4 P4 P 10 D 12 8 10 R4 E4 A4 C8 G8 010 045 862 C42 C16 820 C29 C19 C11 828 C34 C12 804 DOS D20 L 10 P 11 N 11 N-10 M 13 F-14 D 13 C 10 C 11 8 11 E 10 8 D39 836 C26 848 C37 846 COS 819 C24 842 C50 832 D25 M-9 P9 M-11 N-12 K 13 K 14 F 13 C 12 0 11 8-9 D-9 10 042 D44 821 C28 840 C35 825 C01 829 C43 849 D49 004 K -9 A7 L 12 L 13 H-11 E 13 E 12 R-7 F-9 11 048 CO2 811 C46 C44 C31 CIO C33 834 C25 005 J 15 J 10 J-14 L 14 H-15 E 14 G 14 G 10 G 15 12 014 007 813' B10 E44 801 826 D15 D24 J-12 K 11 H-13 F 11 G 12 13 D23 D12 D37 830 D28 046 D26 H-9 D13 D17 D06 15 0*
A REGION 1 (2.1 w/o) D STA D -
- LED FACE 4 es e REL Ry.2i?. , w w 8 REGION 2 (2 6 w/o) Z OPTIr 4ED FUw ." ED y w
w C REGICN 3 (3.1 w/ol FACE 2 XXX ASSEMBLY IDENTIFICATION Figure 3 3. Cycle 2 Core Loading Pattern 3-6
WESTINGHOUSE PROPRIETARY CLASS 3 10'l ~ 102 8 _
LEGEND:
6 -
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6 l-133 4 _ O l 131 O l-131/1133 2 - A BEAVER VALLEV UNIT 1 10-2 -
101 0 8 0 b
o 6 3 O w
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10 0{n
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6 -
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Figure 3-4. Cycle 2 Coolant Activity 3-7
WESTINGH0USE PROPRIETARY CLASS 3 LEGEND:
O EOC-1 O EOC-2 N
2.0 N
\ WESTINGHOUSE
\ RECOMMENDED BORON /
\ \
,,,a LITHlUM CONCENTRATION
< N sN 1.5 -
3 N s
\
1.0 -
N N k '\
N %
MINIMUM LITHlUM CONCENTRATION \
FOR ZERO TEMPERATURE COEFFICIENT Q C--
OF SOLUBILITY AT 2850C 0.5 -
0.0 1200 1100 1000 900 800 700 600 500 400 300 200 100 0 ppm B i
i Figure 3-5. Boron Versus Lithium Concentration in DLW's Reactor Coolant During Cycle 1 and Cycle 2 3-8 b
i WESTINGHOUSE PROPRIETARY CLASS 3
, 4.0 FUEL EXAMINATION i At the end of cycle 2, Duquesne Light Company and Westinghouse conducted j a planned, non-destructive visual examinations, one hundred fifty-three i assemblies were examined by binocular to assess the overall integrity i (the assemblies are listed in Table 4-1); ten (10) fuel assemblies from Regions 2 and 3 were examined by T.V. visuals to assess fuel assembly and fuel rod mechanical integrity, distribution of crud deposits, t
corrosion of fuel rod surfaces, and fuel rod bow (the assemblies examined are listed in Table 4-2); twenty Region 4 fuel assemblies located adjacent to the core baffle were examined by T.V. visuals for effects of possible coolant cross flow through baffle joints (the assemblies are listed in Table 4-6).
In addition, several fuel assemblies, supplementary to the planned pro-gram were examined. The fuel assemblies examined and the reason for the examination are given in Table 4-3.
4.1 BINOCULAR EXAMINATION As fuel assemblies were transferred from the upender to the fuel storage rack in the spent fuel pool, 153 were viewed from above water at the side of the pool with 7X binoculars, to assess the overall condition.
l Examinations were performed on one (1) Region 1 assembly, 50 (fifty)
Region 2 assemblies, 49 (forty-nine) Region 3 assemblies, 47 (forty-seven Region 4 assemblies and 6 (six) Region 5 assemblies (new assem-blies).
Each assembly was examined as it was rotated about its longitudinal axis before it was inserted into the storage rack. The binocular examinatien did not reveal any anomalies such as failed rods, damaged grids, unusual conditions of rod bow, or unusual crud distribution or corrosion on peripheral fuel rods which could reouire a more detailed examination with underwater television.
4-1 0239L:6
WESTINGHOUSE PROPRIETARY CLASS 3 TABLE 4-1 BEAVER VALLEY EOC-2 BINOCULAR EXAMINATION OF ASSEMBLIES Region 1 Region 2 Region 3 Region 4 Region 5 All B01 C01 ZD1 E14 B02 C02 ZD2 E36 B03 C03 001 E10 B04 C05 002 E40 B05 C06 003 E46 B07 C07 D04 E44 B08 C08 D05 B09 C09 006 B10 C10 D07 B11 C11 008 B12 C12 D09 B13 C13 011 B14 C14 D12 B15 CIS D13 B16 C16 D14 B17 C17 D15 B18 C18 D16 B19 C19 D17 B20 C21 D18 B21 C22 D19 B22 C23 D20 B23 C24 D21 B24 C25 022 825 C26 023 B26 C27 D24 B27 C28 D25 B28 C29 D26 -
B29 C31 D27 B30 C32 028 B31 C33 029 B32 C34 D31 B33 C35 D32 B34 C36 033 B35 C37 D34 836 C38 D35 B37 C39 D36 B38 C40 038 B39 C41 039 B40 C42 040 B41 C43 041 B42 C44 043 B43 C45 D44 '
844 C46 045 B45 C47 D46 B46 C48 047 B47 C49 D48 )
848 C50 D49 \
B49 C51 B51 C52 B52 4-2 0239L:6
UESTINGHOUSE PROPRIETARY CLASS 3 TABLE 4-2 BEAVER VALLEY UNIT 1 PLANNED E0C-2 T.V. VISUAL EXAMINATION Fuel -Core Assembly No. Location Comment B04 C09 Examined at E0C-1 B07 LO6 Examined at EOC-1 B13 K13 Examined at E0C-1 B20 K09 Examined at EOC-1 B31 E04 Examined at EOC-1 C03 G08 Examined at EOC-1 C06 006 Examined at EOC-1 CIS J05 Examined at E0C-1 C39 M08 Examined at EOC-1 C49 LOS Examined at EOC-1 i i
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I 4-3 0239L:6
WESTINGHOUSE PROPRIETARY CLASS 3 TABLE 4-3 BEAVER VALLEY UNIT 1 UNPLANNED E0C-2 EXAMINATION Core Fuel Location Assembly No. [ Cycle 2) Comment C40 K04 Prematurely lowered in upender C10 G12 Tilt in the core during reload 017 H15 Adjacent to C10 C52 F04 Suspected to be bowed and twisted and suspected to cause C10 to tilt
(
4-4 0239L:6
WESTINGHOUSE PROPRIETARY CLASS 3 l
4.2 TELEVISION EXAMINATION - GENERAL FUEL CONDITION The low magnification television examination was a full face examination of all fuel assembly faces from the bottom nozzle to the top nozzle.
Each fuel assembly was positioned in front of the television camera so that the field of view covered an area 3 x 4 inches of the assembly face. The assembly was lowered or raised in front of the television camera, scanning from nozzle to nozzle. The left half of the assembly face was examined in the first scan, and the right half of the face was examined in the second scan. Routinely, each scan was halted, briefly, ,
at the bottom and top nozzles at each grid and at each mid-span position between grids.
T.V. tapes of the 10 (ten) fuel assemblies, which were also T.V.
visually examined at the EOC-1, 5 (five) from Region 2 and 5 (five) from Region 3 were reviewed to assess general fuel assembly mechanical conditions. All fuel assemblies were in good mechanical condition.
None of the fuel rods, top and bottom nozzles, grids, or hold-down springs were damaged.
T.V. tapes of the 4 (four) fuel assemblies examined supplementary were also reviewed to identify the possible anomaly. Assembly C40 which was prematurely lowered in the upender before it was completely positioned in the upender anc released from the fuel assembly handling tool, showed no damage. Assembly C10, which tilted in the core during the core reload contacting with the norch baffle wall showed no apparent damage; only minor scratches were observed on the assembly. Assembly D17 which was adjacent to C10 showeo no damage. Assembly C52, suspected as being '
bowed and twisted and suspected to cause C10 to tilt showed no unusual conditions.
4.2.1 FUEL RCD SURFACE CONDITION
/ The T.V. tapes of ten representative fuel assemblies from Regions 2 and 3 were reviewed to examine corrosion patterns and crud distribution on fuel rods. No unusual crud deposits or cladding corrosion patterns was ocserved.
4-5 0239L:6
WESTINGHOUSE PROPRIETARY CLASS 3 fuel. rods for Regions 2 and 3 exhibited the same general appearance.
The fuel rod surfaces at the EOC-2 were generally similar to the E0C-1 observations with the additional deposition of crud during cycle 2.
Figure 4-1 illustrates the comparison between E0C-1 and EOC-2 fuel rod surface appearance at corresponding elevation for assembly C49. The fuel rod surface from spans 1 through span 4 exhibited a mottle appear-ance similar to span 3 at the EOC-1. Spans 5 through 7 showed a rela-tively dark non-reflective and uniformly distributed crud.
The comparison between the EOC-1 and E0C-2 distribution suggests that the crud build up in cycle 2 is less than that in cycle 1. Less crud deposition in the observed cycle 2 is attributed to the high lithium concentration in cycle 2 as mentioned in Section 3.
4.2.2 PERIPHERAL FUEL ROD CHANNEL CLOSURE Ten representative fuel assemblies from Regions 2 and 3 were evaluated to determine the peripheral rod channel closure with a low magnification T.V. Instead of measuring the data for every channel, only channel closures greater than [ ] percent were measu-ed. Each closure was (a,c) calculated from the expression M
CLOSURE =
[1- 155]x100 wnere 2
M = spacing between two adjacent fuel rods at mid-span location between grids T = spacing between two adjacent fuel rods at the top of the grid span B = spacing between two adjacent fuel rods at the bottom of the grid span
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Figure 4-1 Surface Condition of Peripheral Fuel Rods in Beaver Valley Fuel Assembly C49 Face 3 Left Side E0C-1 and E0C-2 (Sheet 2 of 4)
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Figure 4-1 Surface Condition of Peripheral Fuel Rods in Beaver Valley Fuel Assembly C49 Face 3 Left Side E0C-1 and E0C-2 (Sheet 3 of 4)
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Figure 4-1 Surface Condition of Peripheral Fuel Rods in Beaver Valley Fuel Assembly C49 Face 3 Left Side E0C-1 and E0C-2 (Sheet 4 of 4)
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WESTINGHOUSE PROPRIETARY CLASS 3 The largest closure observed at E0C-2 was [ ] percent, the channel (b,c) i between rods 10 and 11, span 4, face 4 of Region 2 fuel assembly B13.
l The closure is shown in figure 4-2. This channel was [ ] percent (b,c)
- closed at E0C-1. Only [ ] of the 10880 peripheral channels (b,c) examined were closed [ ] percent or more. Table 4-4 lists all channels (b,c) with greater than [ ] percent closure. A summary of the closure for (b,c) each assembly is given in the Appendix A. ,
1 J
The axial variation of channel closure in each region is shown in figure 4-3. The span 1 closure in figure 4-3 has been normalized to compensate for the longer length of the first span (24 inches in span 1 and 20 inches in the upper span), The closure in span 1 was normalized by the ratio Q0)2. (This is derived from ratio of flexural rigidity 24 (I/1)2 between 24-inch-span and 20-inch-span). The worst span closure occurred in span 4 for Region 2 assemblies and span 2 for the Region 3 assemblies as can be seen in figure 4-3. The occurrence of worst-span closura in the bottom half of the fuel assembly was also observed in previous examination of Trojan 8 grid 17 x 17 fuel (6) , Salem 8 grid, 17x17 fuel (5) and the Surry 7 grid, 17x17 demonstration fuel l assemblies ( ' ) In figure 4-4, the 95th percentile closure in the l worst-axial grid span of Beaver Valley at EOC-1 and EOC-2 as well as i Surry 7 grid 17x17 assemblies, Trojan 8 grid 17x17 assemblies and Salem i 1
8 grid 17x17 assemblies are shown. The rod bow design limit curve approved by the NRC is also shown. The Surry data (7 grid) have been normalized to the same length as the 8 grid standard 17x17 fuel in other reactors. As seen in figure 4-4, Beaver Valley closures are well below the design curve for the 8 grid 17x17 design and consistent with other data.
4.2.3 PERIPHERAL FUEL ROD-TO-N0ZZLE GAP AND ROD GROWTH f
The axial gap between peripheral fuel rod and assembly nozzle for nine y assemolies, B04, 807, B13, B20, B31, C03, C06, C15 and C39 was measured from the low magnification image on the television monitor.
4-11 0239L:6
WESTINGHOUSE PROPRIETARY CLASS 3 TABLE 4-4 FUEL R0D CHANNEL CLOSURES [ ] PERCENT IN BEAVER VALLEY UNIT 1 FUEL AT EOC-2 r
Assembly Face Span Rod EOC-1 EOC-2 B07 (b,c)
B13 B31 CIS C39 r
C49 4-12 0239L:6
Westinghouse Proprietary Class 3
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B13, Face 4 Span 4 between Rods 10 and 11 ,
l 4-13
WESTINGHOUSE PROPRIETARY CLASS 3 3760 50 g 40 -
E a
3 30 -
o 3
P (b, c)
$ 20 -
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0 0 1 2 3 4 5 6 7 GRID SPAN i
Figure 4-3. EOC-2 Axial Variation in 95th Percentile Peripheral Fuel Rod Channel Closure in Beaver Valley Unit 1 4-14 l
1.0 (b, c) 0.8 -
E o s O E s -<
U 0.6 -
DESIGN VALUE 17x17 E y HOT 8-GRID @
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NOTE: ACTUAL DATA ARE FOR COLD $
CONDITIONS; MULTIPLY BY 1.2 FACTOR w TO COMPARE WITH NRC DESIGN CURVE 0.0 0 5000 10000 15000 20000 25000 30000 35000 REGION BURNUP (MWD /MTU x 10-3) g 8
Figure 4-4. Worst-Span Channel Closure Behavior at the 95th Percentile Level
i
! WESTINGHOUSE PROPRIETARY CLASS 3 The low magnification television measurements of rod-to-nozzle gaps were calibrated for each fuel assembly face by measuring the television image
- of several grid springs (approximately the same length as the rod-to-nozzle gap) on the outside straps in the top grid and bottom grid on each assembly face. Measurements were taken from the television screen with drafting dividers and scaled from a machinist's ruler divided in 5
0.01-inch increments. The spring siot lengths on each top grid on each assembly face were averaged ano used as a standard for determining the top nozzle-to-rod gaps on that face. .Similarly, the spring slot lengths on each bottom grid were averaged and used as a standard for determining the bottom nozzle-to-rod gap on that face. The uncertainty in the cali-bration measurements and the rod-to-nozzle gap measurements was 5 per-cent.
1 The frequency distribution of total rod-to-nozzle gap (bottom plus top rod-to-nozzle gap) is shown in figure 4-5. The total rod-to-nozzle gap
- range from [ ] to [ ] inches with an average of [ ] inches for (b,c)
Region 2 assemblies and [ ] for Region 3 assemblies. Table 4-5 (b,c)
, shows a summary of the average bottom gap, top gap, total gap and the maximum and minimum for the total gap. Figure 4-6 shows a typical example of face to face variations of top and bottom nozzle gaps in assembly B13. A decrease in the rod-to-nozzle gap at the top implies upward movement of the rod. A decrease in the gap at the bottom implies a downward movement of the rod. If the top gap remains uneffected, but i the bottom gap decreases, rods are growing downwards. Slippage would be i manifested as a decrease in the bottom gap and an increase in the top gap. The data generally show a downward growth, with substantial closure of bottom gap and little change in the top gap. This trend is consistent with data from other plants. Figure 4-6 shows that the bottom gaps on faces 1, 4 and 2 have changed slightly more from the nominal pre-irradiation value than the gaps of face 3. As shown in figure 3-3, face 3 of assembly B13 is located the farthest from the center of th9 core and will have the least burnuo and since growth is burnup dependent, this observation is expected. One rod (red 6) of face i I 2 of B13 was in contact with the bottom nozzle but it can be seen from figures 4-6 and 4-7 that the same rod has a larger top gap than the i
! 4-16 0239L:6 1
WESTINGHOUSE PROPRIETARY CLASS 3 3760 40 30 - (b, c)
W o
$ 20 -
8 e
u.
10 -
0 -
0.60 0.70 0.80 0.90 1.00 1.10 1.20 1.30 1.40 1.50 1.60 1.70 ROD TO NOZZLE GAP (inches) TOTAL Figure 4 5. EOC-2 Distribution ot' Peripheral Fuel Rod to Nozzle Gaps (Bottom Gap Plus Top Gap) in Beaver Valley 4-17
WESTINGHOUSE PROPRIETARY CLASS 3 3760 1.1 NOMINAL PREIRRADIATION GAP -
(TOP AND BOTTOM) 1.0 -
0.9 -
y 0.8 -
5 0.7 -
(b, c) 0 0.6 -
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1 5 9 13 17 5 9 13 17 5 9 13 17 5 9 13 17 e - FACE 1 : : FACE 4 : : FACE 3 z' ; FACE 2 -->
ROD NUMBER l
Figure 4-6. Face-to-Face Variation of Rod to-Nozzle Gap in Fuel Assembly B13 After Two Cycles of Operation i
4-18
WESTINGHOUSE PROPRIETARY CLASS 3 1 nominal pre-irradiation value which indicates that there has been some downward slippage of the rod through the grid cell. The top gaps on the average for all faces of assembly B13 show a larger value than the nominal pre-irradiated value which is due primarily to a small amount of downward slippage of the rods.
One rod was observed to be in contact with the top riozzle, assembly 804, face 1, rod 3. Figure 4-8 shows the top and bottom gap for assembly B04 at the EOC-1 and E0C-2. The fact that the clearance between the rod and the bottom nozzle was also much larger than that of adjacent rods suggests that the rod has moved physically upward. As shown in figure 4-8, at the time when the visual examination was conducted at the EOC-1, rod 3 had the same axial position at the top as adjacent rods. The reason for the rod movement is not understood and is not consistent with prior 17x17 fuel examination experience.
Figure 4-7 shows typical rod-to-nozzle gaps at the EOC-1 and EOC-2.
This figure shows that the bottom gap was substantially reduced at the higher burnup, while the top gap changed very little. Figures 4-9 and 4-10 respectively, show bottom gap change and top gap change data obtained for the nine assemblies as a function of region average burnup, and compare with data from several other plants is also il.lustrated.
These figures indicate that the gap changes observed in Beaver Valley are consistent with the gap changes seen in other plants. As shown in figures 4-7 and 4-9, the bottom gap decreases continuously with burnup.
However, the top gap changes little with burnup. This observation implies that fuel rods tend to grow predominantly downward until the bottom gap is fully closed, although occasionally fuel rods slip slightly downward through the grids. The gap data obtained for Beaver Valley assemblies indicate than an adequate rod-to-nozzle gap exists to accommodate continued rod growth for further cycles of irradiation.
4-19 0239L:6
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I WESTINGHOUSE PROPRIETARY CLASS 3 Fuel rod growth for each rod examined was derived from the rod-to nozzle gap data and the predicted fuel assembly growth based upon data from other sites.
Fuel rod growth was derived from the gap measurements using the equa-tion:
Rod Growth = 100 x [ A+B-C ]
D A = Preirradiation nominal total gap 2
B = Irradiation change in nozzle-to-nozzle length (nominal preirradiation nozzle-to-nozzle length times the EOC-2 assembly growth)
Nominal preirradiated nozzle-to-nozzle length = [ ] (a,c) l C = EOC-2 rod-to-nozzle gap D = Preirradiation nominal rod length = [ ] (a,c)
. Fuel rod growth after 2 cycles, summarized in Table 4-5 range from [ ] (b,c) to [ ] percent with a mean of [ ] percent for Region 2 and [ ] (b,c) percent for Region 3.
Figure 4-11 plots the combined rod growth data for the nine Beaver Valley assemblies as a function of fast fluence, together with data from several other plants. The Beaver Valley rod growth data are consistent with the data obtained from other plants.
Figure 4-11 shows that there is a large degree of variability in rod
! growth among the peripheral rods, probably resulting from varying i
4 w
i 4-22 0239L:6
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WESTINGHOUSE PROPRIETARY CLASS 3 3760 100 3
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-50 0 10 20 30 40 BURNUP (x 103MWD /MTU) l l 1 1
Figure 4-9. Bottom Gap Change Versus Burnup 4-24 l _
WESTINGHOUSE PROPRIETARY CLASS 3 3760 100 (b, c)
]
4 50 -
6 C
o F-E w
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z O
-50 I I l 0 10 20 30 40 3
SURNUP (x 10 MWD /MTU)
Figure 410. Top Gap Change Versus Burnup 4-25
t WESTIN2 HOUSE PROPRIETARY CLASS 3 3760 101 9 -
S- -
7 -
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5 -
(b, c) 4 -
3 -
2 -
=
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I I I I I l III I I I I I IIi 10-1 10-1 2 3 4 5 6789100 2 3 4 5 6789101 2
ASSEMBLY AVERAGE FAST FLUENCE (x 1021 n/cm ) (E > MeV)
Figure 411. Fuel Rod Growth Variation with Fluence 4-26
. l
Yk WESTINGHOUSE PROPRIETARY CLASS 3 fluences, slight difference in metallurgical conditions of the tubing, and varying amounts of stress components from red to rod. Irradiation growth studies have shown that the free growth components increases with fast fluence and is strongly dependent on cladding texture, degree of cold work, and heat treatment. Additionally, Zircaloy growth is influenced by stress components which act on the Zircaloy structure, due to externally applied grid forces and internally applied fuel pellet forces.
4.2.4 EXAMINATION OF FUEL ASSEMBLIES AT BAFFLE JOINT Recent fuel inspections at several reactors reveal that when coolant cross flow through leaking baffle joints impinges against peripheral fuel rods, fuel rod vibration and resultant fretting wear in the grids may occur. Since Beaver Valley has similar baffle joint geometries (center injection joints) to plants where damage has beta observed, assemblies in Beaver Valley adjacent to these joint types were examined. Twenty fuel assemblies were inspected to determine the condition of the fuel reos and of corresponding grid cells located adjacent to the baffle jotets. The core locations of these assemblies are shown in figure 4-12. The examinations were performed on seven rods on the face of the assembly directly adjacent to the center injection baffle joint using two high magnification scans with four rods per scan (one rod overlap); Table 4-6 lists the assemblies, faces, and fuel rods that were examinec:.
None of the rods in the 20 region 4 fuel assemblies examined showed g obvious baffle joint flow induced rod damage such as ocen defects, cracks, axial clad splits, worn clad flats, or detectable cnannel spac-ing reduction at grids. However, T.V. visual examinations indicatec that several assemblies exhibited clean white marks en the grids. Thus ar indication of minor baffle joint flow. The assemblies, faces, grids at.d rod locations exnibiting the marks are summarized in Table 4-7. A typical example of the clean white mark is shown in figure 4-13. In 4-27 0239L:6
WESTINGHOUSE PROPRIETARY CLASS 3 addition to this evidence of minor jetting, other characteristics of jetting from flow were noted. Rod 12 on face 3 of assembly D36 exhibited about 1/4 inch downward slippage as shown in figure 4-14.
This is believed to be due to excessive vibration and grid cell relaxation. Three assemblies 038, 024 and 009 exhibited rod bow cue to the Bernoulli effect. The rod bow was caused by Bernoulli forces generated due to pressure difference around the rods due to crossflow through the baffle joint. Bernoulli rod bow occurred directly opposite the jet in the lower grid spans. Figure 4-15a illustrates the mechanism of the Bernoulli effect. Figure 4-15 shows an instance of Bernoulli bow for fuel assembly 024. Another indication of baffle joint flow was a clean darker clad surface along the rod generally seen on rod number 3 counted from the assembly corner closest to the center injection baffle joint.
None of the assemblies exhibited evidence of fuel rod failure, or damage due to baffle jetting sufficient to prevent the fuel assemblies from being reloaded for continued irradiation.
4-28 0239L:6
248 s14 WESTINGHOUSE PROPRIETARY CLASS 3 R P N M L K J H G F E D C B A 180" 1
2 ID !D09 t_36 > D38,! $
3 ID32 IDY8 t-> t 1 &
4 l _
D] 001 5 ID43 6 D41 034
--> ie 7 NOTE: ARROW INDICATES DIRECTION OF COOLANT 9 CROSS FLOW IN EVENT OF 270 8
BAFFLE JOINT LEAKAGE.
9 l --> e-10 D39 D25 11 D4);
A *-A -
12 DO5I D$1 13 _-
h4f A A *-A 14 D12 ID46 D26i 15 FACE 4 0 l FACE 3 FACE 1 1
FACE 2 l
l Figure 4-12. Location of Fuel Assemblies Examined for Effects of Coolant Cross Flow Through Baffle Joints 4 29
WESTINGHOUSE PROPRIETARY CLASS 3 TABLE 4-6 BEAVER VALLEY EOC-2 HIGH MAG T.V. VISUALS OF BAFFLE ASSEMBLIES Assembly Number Core Position Face Rods D09 F01 3 1-8 4 10-17 046 F14 2 1-8 3 10-17 D26 E14 1 10-17 4 1-8 D36 LO2 3 10-17 2 1-8 032 M03 3 10-17 2 1-8 D24 D13 1 11-17 4 1-7 D14 M13 1 1-7 2 11-17 018 003 3 1-7 4 11-17 038 K02 1 11-17 4 1-7 D12 K14 1 1-7 2 11-17 D41 P06 2 1-7 3 11-17 D34 B06 1 1-7 2 11-17 D21 N04 2 1-7 3 11-17 D48 N12 1 1-7
- 11-17 D01 C04 3 1-7 4 11-17 005 C12 1 11-17 4 1-7 4-30 0239L:6
WESTINGHOUSE PROPRIETARY CLASS 3 4L TABLE 4-6 (Cont'd)
BEAVER VALLEY E0C-2 HIGH MAG T.V. VISUALS OF BAFFLE ASSEMBLIES Assembly Number Core Position Face Rods D43 B05 3 1-7 4 11-17 042 P11 1 1-7 2 11-17 D25 B10 1 11-17 4 1-7 039 P10 3 1-7 j 4 11-17 4-31 0239L:6
WESTINGHOUSE PROPRZETARY CLASS 3 TABLE 4-7 ASSEMBLIES EXHIBITING CLEAN WHITE MARK ON GRIDS Assemblics No. Face No. Grid No.* Rod Location **
D41 3 4,5,6 between rods 2 and 3 034 1 5,6 D38 4 4.5,6 l
D32 3 3,4,5,6 " I l
D46 2 3,4,5 "
D25 1 4,5,6 "
- Grid location counted from the bottom of the assembly.
- Rod counted from the assembly corner closest to the center injection baffle joint.
4-32 0239L:6 l
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Westinghouse Proprietary Class 3 i
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'4 Figure 4-13 Example of ilhite Clean fiark on Grid 6 on Face 3 of Assembly D41 4-33
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i Figure 4-14 Assembly D36 Face 3 (Rod 12 Exhibits Downward Slippage) 4-34
2m3 WESTINGHOUSE PROPRIETARY CLASS 3 BAFFLE PLATE (3) l BAFFLE PLATE I
I I
l P P 2 2 V
(4) - -(4)
\ '
(2) (2) ol FUEL I i FUEL I O P2 P2 P, P, (1) P,. COOLANT PRESSURE P:2 COOLANT PRESSURE P, > P2 (2) BERNOULLI FORCE WORKED ON ROD (3) BAFFLE JETTING CROSS FLOW (4) CROSS FLOW AROUND ROD GENERATED BY BAFFLE JETTING FLOW Figure 4-15A. Illustration of Mechanism of Channel Closure Due to Bernoulli Effect 4-35 l
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i Figure 4-15 Detectable Reduction in Channel Between Rods 15 and 16 at Midspan Between Grids 1 and 2 on Face 1 of Assembly D24 4-36
UESTlNGHOUSE PROPRIETARY CLASS 3 SECTION 5 CONCLUSIONS The examination of a representative sample of Beaver Valley Unit 1 fuel assemblies after two cycles of operation showed the assemblies to be in excellent condition. Crud deposits were moderate, there was no evidence of thick crud of the type which could cause concern for excessive cladding corrosion.
Less than [ ] percent of the peripheral fuel rod channels in 10 (b,c) assemblies examined were closed [ ] percent or more due to rod bow. (b.c)
The 95th percentile worst-span rod bow is consistent with other 17x17 data and well within the NRC design limit. Rod growth was observed to be consistent with other 17x17 data; ample fuel rod-to-nozzle gap exists for continued irradiation without risk of interference. Examination of 20 assemblies adjacent to center injection baffle joints showed no gross baffle joint flow induced rod damage such as open defects, cracks, worn clad flats or detectable channel spacing reduction at the grids.
However, evidence of minor jetting at the joints was noted.
k 5-1 0239L:6 l
l 1
WESTINGHOUSE PROPRIETARY CLASS 3 SECTION 6 i
REFERENCES
! 1. W. G. Kotsenas, J. B. Melehan, First Cycle Performance of Beaver Valley Unit 1 Fuel, WCAP-9731, August, 1980. (Westingnouse Proprietary) i
- 2. P. H. Huang, L. A. Klotz, The Nuclear Design and Core Management of the Beaver Valley Unit 1 Power Plant Cycle 3, WCAP-10037, February, 1982. (Westinghouse Proprietary) i i 3. Solomon Y., and J. Roesmer, Some Observations on the Possible Relationship of Reactor Coolant Chemistry and Radiation Level Buildup, WCAP-9407, November, 1978.
1 i
- 4. Sweeton, F. H. and C. F. Baes Jr. , The Solubility of Magnetite and 4 Hydrolysis of Ferrous Ion in Aoueous Solutions at Elevated Temperatures, J. Chem Thermodyn 2, pp 479-500 (1970).
) 5. H. Kunishi, Second_ Cycle Performance of Salem Unit 1 Fuel _,
WCAP-9874, May, 1981. (Westinghouse Proprietary)
- 6. J. B. Melehan, et al., Trojan Cycle 3 Fuel Performance, WCAP-9963, December, 1981. (Westinghouse Proprietary) i i 7. DeStefano, J. et al . , Interim Report Surry Unit 1 EOC-3 Onsite Fuel Examination of 17x17 Demonstration Assemblies after Two Cycles of Exposure, WCAP-9139, June, 1978.
- 8. Schmidt, G. R., et al., Interim Report Surry Unit 2 EOC-3 Fuel Examination of 17x17 Demonstration Assemblies after Two Cycles of Exposure, WCAP-9233, January, 1979.
l l
\
l 6-1 0239L:6 i
UESTINGHOUSE PROPRIETARY CLASS 3 APPENDIX A
SUMMARY
OF PERIPHERAL ROD CHANNEL CLOSURES IN BEAVER VALLEY UNIT 1 FUEL ASSEMBLIES A
0239L:6
WESTlNGHOUSE PROPRIETARY CLASS 3 Fuel Number cf Channel Closures in Magnitude Ranges Assembly Span B04 7 6 (b,c) 5 (EOC-1) 4 3
2 1
Fuel Number of Channel Closures in Magnitude Ranges As sembly Sean 804 7 (b,c) 5 (E0C-2) 4 3
2 1
A-1 0239L:6
WESTINGHOUSE PROPRIETARY CLASS 3 Fuel Number of Channel Closures in Magnitude Ranges Assembly Span 807 7 6 (b,c) 5 (EOC-1) 4 3
2 1
Fuel Number of Channel Closures in Magnitude Ranges Assembly Span B07 7 6
(b,c) 5 (EOC-2) 4 3
2 1
A-2 0239L:6
WESTINGHOUSE PROPRZETARY CLASS 3 Fuel Number of Channel Closures in Magnitude Ranges Assembly Span B13 7 6
(b,c) 5 (EOC-1) 4 3
2 1
Fuel Number of Cnannel Closures in Magnitude Ranges Assembly Span B13 7 6
(b,c) 5 (EOC-2) 4 3
2 1
A-3 0239L:6 l
WESTINGHOUSE PROPRIETARY CLASS 3 Fuel Number of Channel Closures in Magnitude Ranges Assembly Span B20 7 (b,c) 6 5
(EOC-1) 4 3
2 1
Fuel Number of Channel Closures in Magnitude Ranges Assembly Span B20 7 (b,c) 6 5
(EOC-2) 4 3
2 1
A-4 0239L:6
WESTINGH0'JSE PROPRIETARY CLASS 3 i Fuel Number of Channel Closures in Magnitude Ranges l
Assembly Span 831 7 6 (b,c) 5 (EOC-1) 4 3
2 1
Fuel Number of Channel Closures in Magnitude Ranges Assembly Span B31 7 6
(b,c) 5 (EOC-2) 4 3
2 1
4
)
A-5 0239L:6
WESTINGHOUSE PROPk!ETARY CLASS 3 Fuel Number of Channel Closures in Magnitude Ranges Assembly Span C03 7 (b,c) 6 5
(EOC-1) 4 3
2 1
Fuel Number of Channel Closures in Magnitude Ranges Assembly Span C03 7 6
(b,c) 5 (EOC-2) 4 3
2 1
(
A-5 0239L:6 l
WEST 1NGHOUSE PROPRIETARY CLASS 3 Fuel Number of Channel Closures in Magnitude Ranges Assembly Span C06 7 6 (b,c) 5 (EOC-1) 4 3
2 1
l Fuel Number of Channel Closures in Magnitude Ranges Assembly Span j l
C06 7 6
(b,c) 5 (EOC-2) 4 3
2 1
{
A-7 0239L:6
WESTINGHOUSE PROPRIETARY CLASS 3 Fuel Number of Channel Closures in Magnitude Ranges Assembly Span C15 7 6 (b,c) 5 (EOC-1) 4 3
2 1
1 Fuel Number of Channel Closures in Magnitude Ranges Assembly Span C15 7 6
5 (EOC-2) 4 3
2 1
I A-8 0239L:6
WESTINGHOUSE PROPRZETARY CLASS 3 Fuel Number of Channel Closures in Magnitude Ranges Assembly Span C39 7 6 (b,c) 5 (EOC-1) 4 3
2 1
l l
l Fuel Number of Channel Closures in Magnitude Ranges Assembly Span C39 7 6
,c) 5 (EOC-2) 4 3
2 1
i A-9 0239L:6
WESTINGHOUSE PROPRIETARY CLASS 3 i
Fuel Number of Channel Closures in Magnitude Ranges Assembly Span C49 7 6
(b,c) 5 (EOC-1) 4 3 ,
2 1
Fuel Number of Channel Closures in Magnitude Ranges Assembly Span C49 7 6 (b,c) 5 (EOC-2) 4 3
2 1
A-10 0239L:6
, . . . . . . . __ .. .. . .