ML20041C646
| ML20041C646 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 06/06/1982 |
| From: | Gorman J, Oboyle D AFFILIATION NOT ASSIGNED, COMMONWEALTH EDISON CO. |
| To: | |
| Shared Package | |
| ML20041C631 | List: |
| References | |
| NUDOCS 8203020412 | |
| Download: ML20041C646 (14) | |
Text
_ . .
I ANALYSIS OF BWR FUEL CHANNEL DEFORMATION Dennis R. O'Boyle Commonwealth Edison Company Chicago, Illinois Jeffrey A. Gorman Dominion Engineering, Inc.
McLean, Virginia Summary of Paper to be Presented at the American Nuclear Society 1982 Annual Meeting June 6-11, 1982 Los Angeles, California i
i 9203020412 820223 PDR ADOCK 05000237 J PDR ATTACHMENT NO. 1
ANALYSIS OF BWR FUEL CHANNEL L r0RMATION Dennis R. O'Boyle Commonwealth Edison Company j Jeffrey A. Gorman I
Dominion Engineering, Inc.
Results of the dimensional inspection of 875 Zircaloy-4 fuel channels irradiated in a BWR-3 were previously reported (Ref.
1). These measurements established that iongitudinal bowing was the dominant deformation mechanism, with side-wall bulging (rounding) next in importance, and with channel twist being relatively insignificant. Results of additional analyses
- of channel deformation mechanisms are discussed herein, with special emphasis on large channel bowing.
The core location histories of 15 channels with he largest longitudinal bows (ranging from 6.25-mm to 9.80-mm), were reviewed to establish the relationship between bowing and flux gradients near the periphery of the core. Based on fuel assembly burnup data and epithermal flux maps, significant fast flux gradients are believed to extend into the core for about four fuel assemblies from the outer edge. The channel material, Zircaloy-4, increases in length in the longitudinal direction due to exposure to a f ast neutron flux. For a channel having uniform metallurgical structure with walls exposed to a flux gradient, the side receiving the higher fluence will grow more, which results in bow. Thus channels located in the peripheral core region are expected to bow toward the core center since the f ast neutron flux decreases near the edge of the Core.
- Work reported in this paper was supported in part by EPRI under Project RP1943-1.
l m
r.
l
. The analysis of channels having the 15 largest bows revealed little correlation with flux gradients since most of the channels were irradiated in mid-core locations. Thus the mechanism j for large channel bow is not the peripheral-core-region flux l gradient. However, all 15 of the channels were bowed in the direction of the non-welded channel faces, which suggests that the two channel halves do not have tht same metallurgical structure and growth rate.
The probable mechanism for large bowing is that the channels were manufactured from " unmatched halves" of Zircaloy i.e.,
the two channel halves were not made from the same side-by-side sheet of material, and differential growth of the two halves occurred during irradiation. This hypothesis is supported by the following: 1.) Exposure to in-core flux gradients does not explain the large bowing. 2.) All 15 of the largest bows occurred in the direction of the non-welded channel sides, which indicates that bowing is due to some non-symmetric property of the two channel halves. 3.) Small changes in texture, cold work, or recrystallization can strongly affect irradiation-induced growth of Zircaloy (Ref. 2). Thus small changes in any of these parameters becween unmatched cha.inel halves could cause large bowing.
4.) The manufacturing method for the channels examined typically resulted in a fraction of the channels having unmatched halves.
The bowing behavior of five channels that had been irradiated in the same core location for four cycles also was investigated. Four of the channels were located in the center of the core, and one was located on the core periphery. The measured deformation and exposure of these channels is summarized in Table
- 1. Significant results are: 1) As expected bowing of the peripr:eral channel (core location 48/5) was larger than that of the central channels. This channel had an equivalent bow of 3.25-mm, and this bow was directed to within a few degrees of the core center. Assuming that the channel was initially straight, its
1 bowing rete was about 0.4-mm per GWD/MTU of burnup. 2.) Bowing of the four central channels appeared to be essentially random in direction and was relatively small (1.1-mm average, 2.0-mm maximum).
Preliminary conclusions based on an analysis of in-core channel deformation are: 1.) The largest channel bows observed are l not caused by peripheral flux gradients but are due to the use of l unmatched channel halves having non-uniform structure and different I growth rates. 2.) Flux gradients at the core periphery cause )
channel bowing toward the core center at a rate of about 0.4-mm per GWD/MTU of burnup for the class of channels measured. 3.) Based on the deformation behavior of channels located in the center of the core for four cycles, bowing of central channels having matched halves is small in magnitude and is essentially random in direction.
- 1. D. R. O'Boyle, H. G. Lihou, and B. R. Strub, " Measured In-Reactor Deformation of BWR Fuel Channels," Trans. Am. Nucl.
Soc., 38, 310 (1981).
- 2. R. B. Adamson, " Irradiation Growth of Zircaloy," Zirconium in the Nuclear Industry, ASTM STP 633, A. L. Lowe, Jr. and G. W. Parry, Eds. ASTM, 1977.
ID: 5949A5
4-I Table 1 MEASURED DEFORmTION OF BWR FUEL CHANNELS IRRADIATED IN QUAD CITIES-1 FOR FOUR CYCIES IN 1HE SAME CORE IDCATION.
End-of-Cycle Burnup, GWD/MIU Maximum Deformation Gamel at EOC-5, m Core Face location Cycle 2 Cycle 3 Cycle 4 Cycle 5 Measured
- Bulge Bw**
30/29 9.82 15.87 24.63 32.34 3 0.84 1.32 4 0.84 -0.36 l 32/31 9.82 15.87 24.63 32.34 3 0.84 1.27 4 0.79 1.22 30/31 9.82 15.87 24.63 32.33 3 0.81 0.56 4 0.84 1.22 32/29 9.82 15.85 23.22 31.05 3 0.81 2.03 4 0.84 -0.69 48/5 2.70 4.21 6.27 8.53 3 0.28+ 2.72 4 0.23+ 1.78
- Channel faces 3 and 4 are both toward the control blade.
- Positive bow is towards the control blade, negative bow is away.
t Snaller bulge results from lower pressure drop across the channel wall in peripheral core location.
ID:5949A5
DEVIATION REPORT O
c zj) Commonwrith Edison I ova co gTAo . 4 -UNf7 2
81 ~ '44 TEAR 50.
_._ i n - il ?!TLE or cEv1AT1oM oCCURREi O-21 -31 0300 f, The Finding of a piece of fuel bundle spacer. DATE Tint PLANT STATUC AT TIME OF SVENT TESTING f1 STEM AFFECTED g MODE Refuel , twRinwT 0 , LeAoinwE 0 hh DESCRIPTION The OF EVENT f uel handlers found a side of ere of a fuel hnnal, ense.r t=utnn rn ,
fuel rack near fuel preparation machine #2.
Apparently during channelling of fuel, as the channel was being installed It knocked off part of a spacer.
The piece was found near FPM #2 where the discharced fuel was havine scent channels installed.
lo CrRso.72 NRc rec PucNE O G WCTIFICATION MADE YES NO EQUIPMENT FAILURE OYES O No we., RECats? o. R..,on.ie!. s o . . . . i .'o r erran o. seems e.,.in-3,_o,
/ pap! 21 OPERATING enc 1NEER'S COMMENTS The spacer was from a fuel bundle beino discharced and war a-narant!v-an isolated case caused by an extremely bowed channel.
a' O tve": or rus'2e tarrats: O 24-"oua "ac "or2r2c^ 2 " arc'o
~
TELEPH O TECE. SPEC. VIOLATION REGION !!! DATE TIME
$ hCN REPOR*ASLE OCCURRENCE TELECM/TELECOPY REGION III CATE TIME Q 14 DAY REPORTA8LE/T.S.
crea com'oaatz "or2r2ca22c" "act O 2o o^r arroa an'z/t.$- IF ABOVE NOT1FICATION !$ PER loCFR21 C ANNUAL /$PECL REPORT REQ'D O 5-car wa222 = arroat arc'o era 2acr=22 A.I.R. I L.E.R. 4 TELEPM DaTE T2"E Ceco CORPORATE OFFICER PRELIMINARY REPORT Rich Robey 10-21-81 COMPLETED AND REVIEWED DATE OPERAT1uG ENGINEER g INVESTICATED REPORT & RESCLUTION ACCEPTEE SY STATION REVIEW G. 7:2A WL/ .
"l':'!!!"b":"';R'"l TIN /[ MIe/ - MfeM 86-5176 (Fom 15-52-1) 10-81
QUAD-CITIES NUCLEAR' POWER STATION DEVIATION REPORT D-4-2-81-44 REPORT DATE: November 25, 1981 DEVIATION DATE: October ~), 1981 es~
IDENTIFICATION OF DEVI ATION: D i. g ,
A side piece of a fuel bundle spacer was found on the fuel pool floor. hotpJ J e.4 9
CONDITIONS PRIOR TO DEVIATION:
Unit 2 was in refueling. The Fuel Handlers were removing channels which were found to exhibit excessive bow or bulge, and placing them on spent fuel bundles.
DESCRIPTION OF DEVIATION:
While the Fuel Fendlers were channeling fuel, one side of a fuel bundle spacer was found on the fuel pool tivve. The piece was fouwl near the fuel prepara-tion machine where the discharged fuel was being channeleo with bowed channels.
To locate the fuel bundle with the missing spacer piece, a Nuclear Component Transfer List was written to examine fuel bundles. Examination began with the fuel bundle which had the most recently installed spent channel. The channels were removed to check the integrity of the fuel bundle. The third fuel bundle inspected, LJ0148, was discovered to have a total of four sides missing on two spacers (SEE FIGURE 1). Close inspection of the fuel pool floor revealed three sides of the spacers.
DESIGNATION OF APPARENT CAUSE OF DEVI ATION:
The apparent cause of this deviation is equipnent failure. Spent channel, CY0151, with a large bow and bulge (SEE FIGURES 2, 3, 4, 5, and 6), was being installed on the fuel bundle. The large bowing of the fuel channel caused a large amount of leverage on the fourth spacer. This large force then sheared off three sides of the fourth spacer and then one side on spacer number 3 ANALYSIS OF DEVIATION:
The safety implications of this occurrence are minimal due to the fact that all ,
channels are measured and discharged if the bow. is excessive. Channels with !
large deformations are then installed on discharged fuel, so it is unlikely that fuel to be loaded would be damaged. Fuel bundle, LJ3367, from which channel CYO151 was removed was examined and found to be intact.
Following the discovery of the spacer pieces, General Electric was consulted ,
concerning the safety significance and the generic applicability of this occur- !
rence. J l
l i
1
. The following conclusions were derived:
- 1. If a similarly damaged bundle were to be loaded and operated in the Reactor, no problems or safety concerns would be encountered.*
- 2. There is small possibility of fuel pin to channel contact but if the channel were to cone in contact with a fuel pin there should be no fuel pin failures.**
3 There will be a slight increase in vibration amplitude but no fuel pin wear should be observed.*
- 4. There is a possible chance of a piece of the spacer causing a flow blockage. However, to cause a blockage a large piece would be required.
This would either prevent proper channel Installation or else become trapped inside a channeled bundle. During transients, broken spacers should not be of great concern because any vibration would be of short duration and any departure from nucleate boiling would be extremely localized (1 or 2 fuel pins in one bundle).
- G.E. experience at a foreign Reactor where five fuel bundles had seven spacers moved as much as 20 inches without detect-able problems.
- G.E. referenced an ASME paper in which fuel pin to channel
( contact resulted in no fuel failures.
General Electric felt that this incident is not an indication of a generic problem of fuel bundle spacers because they have examined spacers wi.th a much higher burn-up and not found embrittlement problems. G.E. has expressed interest to examine the pieces of the spacer at a later date.
CORRECTIVE ACTION:
No further corrective action is needed as the damaged fuel bundle was not scheduled for re-insertion into the Reactor. Also, channels with large
. deformations are not installed on fuel that will be reloaded in the core.
FAILURE DATA:
There is no previous record of spacers being damaged in this maaner. General Electric also is not aware of any spacer damage in the industry.
Prepared By: E- -
Brian R. Strub Approved By: S. M TechnicalSt(ffSupervisor Action item Yes X No AIR Number
SROK EM FUEL ROD SPACERS
, . s9,,,, c\ p FUEL BMNOLE:
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g, FitES 99 +100 C. 4 A u N G t. Ex7o$E b c4 BugDLES 0.10156 A tlD L "I 336 7
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- - , --- - . - - - _ g PROCESSED DATA CHAllHEL cvoisi p DEFLECTION (nlls) EUNDLE LJ3367 EF,Q EQH EML .Tjg SURFACE 4 l 200-- . TA E 18 150.1 0 15 0 -
FIL 100 140,5 74 25 -7 -
DAT :0/09/81 131.0
~
131 41 -13 150- .-
120.9 171 40 -13 110.9 218 58 -10 -
~
100.6 256 58 -13 _
90.6 289 68 -7 100- -
00.0 302 66 1 70.7 295 68 9 : " "
v "_".
60.1 269 72
~
3 -
50.8 243 67 -4 50- -
40.5 221 75 -4 30.2 193 74 -7 -
q' 20.0 149 70 -8 0-
' ' ' 'A ' ' ' ' '
. 10.5 80 56 -6 a' 1 1 ;-' '
'W1 "
O.5 0 33 -11 - -
h) -
-100- -
+ BOW + BULGE n BOW
-150-k BULGE 4 TWIST .
-200 Ei 20 40 60 80 100 120 140 160 ELEVATIDH (in.)
GOING UP '
GOING DOHN TAPE 18 CHAllHEL CYol61 ELEU A B~ C ELEU= ~~~ A B C FILE 100 ButIDLE LJ3367 DATE 10/09/81 SUPFACE 4 f
150.1 98 98 48 150.1 98 88 48 140.5 168 164 111 140.7 169 173 116 l
131.0 222 230 158 130.8 224 234 161
. 120.?
110.9 100.6 254 291 323 262 319 349 190 120.6 231 110.9 260 100.3 258 292 327 276 324 350 197 235 270
[/
/
90.6 346 306 289 90.0 347 390 296 / /
80.0 347 309 298 80.0 346 391 301 / / -
%g 70.7 329 377 288 70.1 327 377 290 /
[/ / /
r
~
60.1 298 346 251 60.5 290 346 259 j e 50.8 269 309 214 50.3 267 309 223 40.5 30.2 20.0 10.5 239 204 153 84 206 250 194 112 184 147 95 27 40.3 30.5 21.0 10.8 239 206 157 87 209 251 198 116 197 147 98 28
,[/[
O.5 -9 -7 -71 0.7 -8 -5 -72 /,
CALIBRATIOH CALIBRATION [
-3.7-248-252-254
-4.5 2 0 -10
-3.7 -250 -250 -261
-4.5 0 0 -15
[
MAX. MISMATCH: 14 AT ELEU : 120.6 MAX. DISPLCMT: 389 AT ELEU : 80.0 j
PROCESSED DATA CHAllHEL cvoist 4 DEFLECTION (nils) BUNDLE LJ3367 ELEIA B.DR R1 IMI 200-- SURFACE 3
~
TAPE 10 150.1 0 9 0 . FILE 99 140.2 -29 2? 1
~
DATE 10/09/81 130.0 -68 25 5 g'50- ~
120.7 -90 29 8 -
110.3 -106 35 20 -
160.1 -118 37 21 :
90.3 -125 40 24 100- -
80.2 -125 38 26 -
70.4 -121 44 34 : .
43 33 60.0 -114 -
50.3 -107 42 33 50- M = r_ . . y __ ,,
^^
40.0 -94 48 32 _
e Z :. M T uh 30.0 -75 48 35 -
2.
i 20.3 -51 50 31 8'
. . . . . . . . . h- .
10.5 -26 ' '
44 ' ' ' '
24 '
(p\ 9.1 0 16 8 - -
-l
-100- -
{ W- ,
- B0H+ BULGE o BOW
- -150- ,
.* BULGE
[ 4 THIST
-200ii 20 40 60 80 100 120 140 160 ELEUATION (in.)
-s G0IldG UP COIllG D04lIl TAPE 10 CHAHHEL cvoisi C ELEU A B C FILE 99 Bull 0LE LJ3367 ELEU A B 3
~~~~ -
DATE 10/09/81 SURFACE I
f 150.1 -7 -21 -53 150.1 -7 -21 -52 h'ef
/'
140.2 -31 -31 -76 140.5 -29 -30 -76 ff
-65 106 130.3 -63 106 ,f l .TTT 130.0 / ff!
. sas 120.7 73 -121 120.9 72 -121 '
/
/ /,
110.3 77 -125 110.0 80 -135 s' / // / !
100.1 -104 130 101.0 -105 137 s 90.3 -107 130 90.3 -106 134
/
j/
I kd' # /'/ -
80.2 -102 123 80.1 -102 127 l
l 70.4 59 -109 70.2 50 -113 60.0 -03 -47 -96 60.4 -85 101
' ,f-f f/j /'
50.3 -70 -35 -83 50.4 -69 82 ,/ f j l
40.0 -50 -9 -64 41.0 -51 64 t
30.0 -23 19 -35 #
30.0 -27 15 -38 -
20.3 6 49 -9 20.8 5 47 -1'8 10.5 41 74 19 10.4 44 76 12 / s 0.1 81 78 43 0.0 82 77 31
{/
CAL 18RATIOH CALIBRAT10H i
-3.7-249-226-245
-4.5 2 1 3 -
-3.7 -248 -250 -257
-4.5 3 1 -12 [pj
/
/ /
i MAX. MISMATCH: 12 AT ELEU : 0.0 /
MAX. DISPLCMT: 81 AT ELEU : 0.1 i
.