Text

Follow-Up Report to Abnormal Occurrence Entitled Correlation of Fuel Failures Identified by Wet Sipping Tests to Calculated Violations of GE Pciomr.
	ML17252A766
Person / Time
Site:	Dresden
Issue date:	06/20/1975
From:	Stephenson B; Commonwealth Edison Co
To:	James Keppler; NRC/RGN-III
References
	Download: ML17252A766 (17)
	v • d • e

Common*lth Edison

One First Na~I Plaza, Chicago, Illinois Address Reply to: Post Office Box 767 Chicago, Illinois 60690

50-24~

ill *-

-*--':'-,~~

BBS Ltr. #"?f3"j-75 Dresden Nuclear Power Station-~-

R. R. #1

Morris, Illinois 60450 June 20, 1975

Mr. James G. Keppler, Regional Director fi:egulatory Docket flle

~ . -------*----:~~~~

Directorat~ of Regulatory Operations-Region III

u. s. Nuclear Regulatory Comnission 799 Roosevelt Road Glen Ellyn, Illinois 60137

SUBJECT:

roLLOW-UP REPORT TO ABNORMAL OCCURRENCE ENTITLED "CORRELATION OF FUEL FAILURES AT DRESDEN-3 IDENTIFIED BY WEI' SIPPlNG TESTS TO CALCULATED VIOLATIONS OF GE FCIOMRll .

Reference:

NRC Exit Interview of May 20,.. 1975

.. *~

Please find attached the iaoove-mentioned report, provided per NRC request of May 20, 1975. .

.~ . '

L B.. B. Stephen

.'\~ Super;Lntendent BBS:smp . - ~ *-

File/NRC JUN

" T*frr-_: James G. Keppler TITLE 9

June 20, 1975 Fuel Failures Identified at D3-EOC3 by Wet Sipping Tests and Com!n~Regarding the PCIOMR.

SUI'<WARY 724 assemblies were wet sipped out of core and total of 113 defective assemblies were identified. General Elec-tric a{:.rreed they were defective as indicated by the fuel contract and were d.ischarged. Twenty-seven high exposure assemblies were also discharged and a total of 140 new assemblies were inserted in the core for cycle 4. All the defective assemblies were 7X7 fuel enriched to 2.13 w/o U-235. The average fuel failure rate was 15.6%. The core was sipped at an average rate of 40 assemblies per day. Table 1 is a listing of the identified failures, their core locations and exposures.

DISCUSSION Figure 1 is a core map indicating the location of the leakers. Pigures 2 to 4 graph three power distributions (equilibrium xenon) typical of the preconditioned shape (2227-Figure 4 (a)) and the spape at 6:57 a.m. on 10-31-74 (1432-Figure 4 (b)). Xenon transients, depending on core location, will increase the bottom peaks by O to 25%.

Failures that don't appear to be related to 10-31-74 are reviewed as follows:

(a) None of the Cycle 2 edge assemblies, includi.~g those n10ved to the center for Cycl~ 3, failed - Figure 6. -

(b) There were three assemblies from cells that had 3 out of 4 failures at EOC-1 that were moved to uncontrolled locations on the edge for Cycles 2 and 3.

None of these three has failed yet.

(c) Four edge assemblies failed during Cycle 3. One,DD0209, was classified as a suspect leaker at EOC-2.

(d) Of 50 Oycle 3 assemblies that were reconstituted at EOC-1, six failed.

All but one may be attributed to 10-31-74.

No GEB (7X7) or DDB (8X8)assemblies were classified as leak.era. The average

exposure of the GEB's was about 4000 MWD/T, and of the DDB's about 2000 MWD/T.

Initially, one GEB (058) and two DDB's (008 and 011) sipped as leakers. The three were resipped twice and found to be sound. To resolve any questions concerning these assemblies, five other assemblies, initially sipped at approx-imately the same time and classified as leakers, were resipped. Again all five

Mr. James G. Keppler June 20, 1975 e

were found to be defe,ctive. Of the 52 GEB' s in the core, 29 exceeded the PCIOMR. Seven .of these dfd so by more than 2 KW/ft, and were among the most severe variations. The differences from the original core 7X7's introduced in the GEB' s include: different fill gas, lower exposure, *tru:-cker cladding, smaller pellet diameter, and shorter pellets with chamfered edges.

Figure 1 indicates that about 80% of the assemblies on the periphery (one assembly removed) of cells that eA"}Jerienced major rod movements (D7, C6, CB and symmetric locations) failed. Figure 7 shows the local power distribution at about 15,000 MWD/T ,for a controlled and an uncontrolled D3 2.13 w/o assembly.

A 2.13 w/o Gd assembly is included to compare the local factors of pins A7 and Gl, which are about 25% higher £or the D3 assemblies.

An analysis was done with a FLARE-type code to determine the kW/ft of nodes that exceeded 8 kW/ft on a pin. The study was done at equilibrium xenon for 12-inch nodes (a correction factor was applied to account for transient xenon). The results are summarized in Figure 8. Only original core fuel is included, and power changes were assumed to be instantaneous. Some comments on the results follow:

(a) The failures do not appear to be related to previous cycle operation.

(b) 22 Failures of 433 assemblies (5%) were at less than 8 kW/ft on 10/31/74.

Thus, none of these was assumed to be related to the October 31, rod movements.

(c) 5 of 74 assemblies (-7%) failed when the envelope (or 8 kW/ft, which ever was greater) was violated by 1 kW/ft or less. The failure rate increased rapidly as the step change above the envelope increased.

(d) The effect on fuel failures of more gradual increases in power, soak periods, exposure, and length of time fuel remains "preconditioned" requires more data than is currently available.

CONCLUSIONS

1. The fuel rod failures related to rod movements on 10/31/74 were probably caused by a pellet-clad interaction mechanism involving highly localized strain leading to cracking of cladding having a low strain-to-fracture capability. Some cracking could also have been promoted by a stress corrosion phenomenon.

2. GE's PCIOMR, based on the assumption that a minimum tensile stress is required to cause such cracking, were in part substantiated: the evidence appears to support the 8 KW/ft threshold and allows some margin above a "preconditioned" shape.

3. Based on past sipping experience and en the observed care with which sipping operations were conducted, the sipping program for D-3 EOC-3 was judged to be very successful, with an estimated effectiveness of at least 90%.

--fAE::>LE I Defective Fuel Assemblies Identified at Dresden-3, End-of-Cycle 3

-~-

P.ssemb ly Core Exoosure Number location (M\IDL'.t)

DD 001 09-30 12,686 021 13-28 13,.018 025 13-38 13,420 036 13-34 13,008 037 31-48 13,576 053 47-34 12,990 064 51-30 12,814 073 09-34 12,891 079 . 45-32 13,015 081 53-20 12,88~

089 11-30 12,805 090 13-32 13,027 093 47-24 13,439 102 13-30 13,030 107 47-32 13, 01~4 111 09-38 12,580 120 39-20 13,321 121 49-26 13,100 127 09-28 12,906

'r ~*.

128 51-34 12,928 129 43-38 . . 13, 368

.132 09-32 12,, 790 134 47-20 13,298

Assembly Nur.1ber e

Core Location Exposure

( MWD /t) 331 51-38 12,536 332 25-38 12,287 343 31-20 12,978 350 43-30 12,317 351 43-26 9,465 364 09-42 12,385 378 11-40 12,741 401' 51-42 11,244 406 07-26 . 12, 958 424 27-32 11,941 425 19-06 11,774

. 431 51-36 10,501 433 09-44 .11,332 436 45-36 12,788 440 53-26 12,619 450 07-32 12,678 455 51-26 10,568 457 35-24 ;, 12, 303 460 43-34 12;679 465 11-1'6 " 12, 858 474 475 17-26 39-28 9,442

. *12, 550 480 15-50 . 12, 904 483 .13-44 10,353 487 . 35-32 12, l l~9

Assembly Number e

Core I..ocation 5 -

Exposure

( MHD /t)

~~

142 47-42 13,292 151 01-30 . 11,531 161 31-12 13,731 162 45-06 11,671 163 11-36 13,061 173 49-32 12,966 175 13-20 13,327 181 49-36 13,101 188 13-42 13,294 191 13-24 13,569 196 47-30 13,044 200 49-30 12,923 204 51-28 12,925 209 47-06 11,342 214 *21-20 13,327 229 29-42 *12, 822 233 47-38 13,437 270 47-28 ..13,114 286 09-36 l0,563 287 . 09-22 10,622 295 07-24 12,653 296 23-30 . 12, 633 300 17-56 11,936 301 '53-36 12,966 319 05-26 11,945

/

Assembly Number e

Core Loe at ion Exposure (MWDLt) 488 07-36 12,530 --~-

491 17-28 12,671 493 53-24 12,678 499 51-22 10,652 511 07~40 12,594 518 53-22 12,663 529 11-18 12,939*

531* 07-44 11,798 537 27-30 ll,944 542 lL-22 12,820 544 07-22 12,636 566 47-26 10,088 573 07-38 12,022 587 25-24. 12,309 613 07-30 12,863 617 11-44 12, 897 . "

618 09-40 10,593 623 53-38 i; 12,"667 624 45-26 12,789 633 49-44 ' 12, 949 .

639 13-26 .. 10, 075 646 13-36 10,060 652 13-40 . 10, 467 663 49-16 12,865 669. 33-30 11,945.

688 49-22 12,802

/

P.ssembly Nuraber

Core Location 8

Expos'.lre (MWD/t)

---~.

693 13-22 10,502

. 698 47-22 10,503 699 49-40 12,791 700 15-36 12,764 705 05-34 12,099 706 09-26 l0,585 710 09-24 12, 519 .

714' 51-40 10,627 7i6 15-26 *12,778 721 17-14 10,356 730 51-20 10,653 745 47-40 10,492 750 53-40 12,648 752 51-24 12', 542 Average exposure of 113 defect:tve a3semblies - 12,29*4 M':tm/t.

--~-

. - *9.: - . . .

Fue1911ures Identified at Dr~en 3.

EOC 3 by Sipping Tests

-~-

0000* **r-~ooo do otj[jo DO l-<'J~~,-**Jl 1

,--*i r::JO DD o-o o-o o~oco*~ D*CJ

L7"'*. C;.='. .Jf~-;'

0 888888 lJQ1GJD{J D~.JOCJ

---*--o 1

l

. ~.

J I

I I

,.I I

s '7 8 . 80 81

-:'t I 4 3 't A-XlF\L' l'\>Ol>c CJ 16.

i/

\

../

I .

J

.1r

-1; .

10

~* . ---. .... - .. .. *-*- *-* *-

'1. . s .Cf 10 II

J I

1-~

/

r

~

\\

~

I.

I\)

>=

/')

II\

--+:

.rw-J_ ,~cu..uv-.... ~ I

-~--~. e

I <j . BO I

r~.

K Eff

/.OOD(~

~. .s _ _..,~.__*.-o_.6:..;;::l...;:;..._____ 0 'j-R)

POvlER LEVEL _ __.....A;....~"--'2__=J_.:....____ t,tyTH C~E INLET SUBCOOLING _ __..;..d~/-'-. ....:5°_ _ _ _ _ BTU/ I e TOT AL CffiE FLO../ _ ___..gc...;:ro:...;..7..:.___ _ _ _ M-le/HR (_""' ~~

PRESSURE _ _-..A..f.._Q-'-/"'-)_ _ _ _ _ PS I A CRD' ]32 O. l:tl DATE OF LAST SE-QUENCE CHANGE .

-ROO PATTERN:

15 1 14 3b ?>h 13 L/D . w 12 4J.j Oo ~2. ~2.. 00 411 11 L/-D .'f-0 4D 10 l32' lb g es I lo ~

9 IW 158 8 :J...b 00 OD IOo Do tzl::

~-

7 B8 *- 36"'

~--;

6 . lb R 8' lb

~).. ~

5 V-1-o 1-/-o 'rf o

4 Lf1 sl. Do

{) 0 2-> l.. ~

3 lfo f./D 2

?~ 5b A B C D E. f G H J K . L M H P R

,4 -

' : . /o-~1-'1t../ e f>:S'l f7M ~

K EFT.

- /.OO°fbt

(_Pt'i-- RJ *

,P()..JER LEVEL ---"-'4=~):..:..;J...;:_..;.____ Mw TH

_ _..:;:,l.~)......:..";....::~::._,...._ _ _ _ _ BTU/1e ccnE INLET.SUBCOOLING TOTAL CCflE fL()..J _ _ _=f~8_:._*.::;:0:....._._ _ _ _ M-le/HR ('v-.-... ~)

PRESSURE ___Cf..:.._;t.....:::b~---- PS I A CRD DATE OF LAST SE-QUENCE CHANGE .

-ROO PATTERN:

. ~

15 14 lf'f ~'I 1 13 H'-f if Lf~

12

~o <? g OD ~

II 4'f IL/1f 'l'f f 10 8 B6 ~b r? l' 9

8 llf;i_ If ~2. ff-,.t t> !Ji.

7 I 6

5 g'

L-/lf

){:,

'fl-/

~

~'f g r I

f- '

4 t?

Do 8 bo 3 'IL/- "f't 2

'i tf ~'I A B c D E f G H J K L M p

~' R Yt 6--Vi RE t-f Cb).

N 1:11'~1, T\....,~_r-11.. \ -s N~ \-\.'\'"""'" 5"' ....

N ~ * ~ ~ ~ ~ 00 ~ 0 = N ~ ~ ~

0 0 0 0 0 - - - - - N N N N N ~ ~ ~ ~ A* A A A A ~ ~ ~ ~ ~

- ~ ~ ~ w - ~ ~ ~ w - ~ ~ ~ w ~

- ~ ~ ~ w - ~ ~ ~ w - ~ ~ ~ w m- .. ' G. * .

D 1

l .

Dn00 ':J D

~ouooc DODJODfJ

~DDDlJtfD 0000 D1lD r:1lO OODDCJL0[Jf0 DO 010 0[] O:CJ f&i OD cro [JD [)O 1

.. vJ

-+- ~ O.CJ [][J OLJ Cl[]

. LJD orJ CJO [TL]

J*.

Q[J CJr:J CJfJ CJ{J

-t . CY=10:0 L

,-"1:r**-**1 l_ _i ~ l_

LJ r-y--1 _1 Ii~ 1\.1] l-1r1 1!1 f f\J

--- "-- L---o>).,_, ,.J:~~*** [- **e:-.Lt..J I' 1CJCJ 0{] [_JD I/"' i

' - - * ~--

I ! -*- : [] :**'] t: "]

~ L,.,.Jb,

,-,*-,,,.J_

!_J{J[JiO

- D 1* *II

/

0000,I 0000~,!n 00000' 00000 0 0 0 0 0 0 /J 0 0 0 0 0 0 t--

I

"':r.*

c -~+ __-___

lJ.J .

1-0.00000'

~ 0 0 000 u

0000 O.O*O @

0 00 . 18 z l l-

\

j:. ~

1

l

\* ~

0

(

.:.i: i ii; Ii : ~::

a

ML17252A766

Text

SUBJECT:

Reference:

Navigation menu

Search