ML20027A287

LER#76-072/03X-1 on 761228:CRD J-11 Uncoupled & Overtraveled When W/Drawn to pos.48.An Unlatched Inner Filter & Abnormally Long Rod Resulted in Coupling of CRD J-11.QA Coverage Improved & Procedures Rev to Prevent Uncoupling

ML20027A287
Person / Time
Site:	Dresden
Issue date:	10/27/1976
From:	Wujciga J COMMONWEALTH EDISON CO.
To:
Shared Package
ML17173A345	List: ML17173A344 ML20027A287
References
LER-76-072-03X, LER-76-72-3X, NUDOCS 7811090142
Download: ML20027A287 (2)

Text

y,g - - . . . . _ . . , , , , , _ . . , . . . , _ . . . . . _ . .

, ,. LICENSEE EVENT REPORT CONTROL BLOCK: l l l l l l 6

lh (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATI:N)

Io IiId III 9 L l LICE?.3EE D I RCODE l S l 2 l@l:5 0 l 0 l- l 0 LICENSE I4 l0l0 l 0 l 0 l- l0 l 0 Nu'A8ER 25 l@l 26 4lLICENSE 1l 1l TYPE 1l 1l@l J0 l

57 GAT 5d l@

Corri loIiI 8

3a[,] l L l@l 0 l 5 l 0 l 0 l 0 l 2 l 3 l 7 l@l 1 ( 2 [ 2 1817 l / I@l1 10 l 2 l 7 l 7 l 8 l@

60 61 OOCKET NUVS ER Gd 63 EVENT DATE 74 75 REPORT oATE 8J EVEfJT DE.SCRIPTION AND PROBABLE CONSEQUENCES h Ioi2I lDuring routine startup operations, CRD J-11 uncoupled and overtraveled when withdrawn ;

ol3l lto pos. 48. Insertion to pos. 46 and subsequent withdrawalto pos. 48 showed drive l lol.l land blade recoupled. CRD J-11 again inserted and withdrawn to pos. 48 and again un- l f o i s ; l coupled. J-11 then inserted and withdrawn again to pos. 48 without incident. Re- l j o go l l coupling verified by cycling the CRD three times. Because the potential for uncoupling g 7J lcxisted only at pos. 48, the safety implications of event were minimal. CRD uncoupling l n3 J l events had occurred before. I d 9 00 SYSTE'A CAUSE CAUSE Co*J P.

CODE VALVE CODE SUSCODE COMPONENT CODE SUSCODE SUSC00E ioi9l d

l R l B l h l A l@ l F l @ l C l R l D l R l V l E lh W@ l_Z_,j h J .J 11 12 I3 13 TJ 20

- S E C'.;EN TI A L OCCURRENCE REVISION REPCRT RE80RT No. CODE TYPE NO.

h .'tg:a.pg l IVENT YEAR l-l

'fyT {! 71 6 !

21 22 23

[ 0 l 71 2 !

04 .6 y

27

[013I 29 23 lX l 30 l-l l11 J1 JJ ACT17N FUTURE EF5ECT SN U TOCWN ATT ACHV ENT N P R D-4 FRivE COMP. COMPONENT T A

• E '4 ACTI O N ON PLAT.T 'AETHOD HOURS .- SUB MITTE D FoRu g:8. SUPPLIE R MANUFACTURER lG JJ i@lJa Z!@ lJaZ l@ lZ ao l@ JJ

[0 l0 l0 !O ! (Y l@ lY l@ l40 Nl@ l G l 0 ! 8 I 047 l@

40 di 42 44 CAUSE GESCRIPTION AND CORRECTIVE 3 0TICNS h

,il0llAn unlatched inner filter and abnormally long uncoupling rod resu3ted in the uncouplind

,l;; lof CRD J-11. Since the earliar overhaul of CRD J-11 in Jan. 1975, a pull test on the !

- , j inner filter has been incorporated in the overhaul & assembly procedure. Revised l

,;3l l procedure and improved 0A coverage is believed adequate to prevent future CRD un- l iia l l couplings,  ;

8 3 80 STA 5 %SQWER OTHER STA TUS IS OV Y DISCOVERY DESCRIPTION .

lt

{sllCl@

8 9 l0l0l0l@l TO 12 11 NA 44 l l45A l@l' Ooerational Event l AC TivlTY CON TE NT 46 80 AELE SED JF RELE ASE A*.90VNT OF ACTIVITY

• LOCATION OF RELEASE -

li NA

' l l z l @ l z!@l i 1 10 11 44 l l 45 NA l I

PERSONNEL E APCSUR ES 80 l

N U*AS E R TYPE DESCRIPTION 39

!71l0!Ol0l@lzl@l 4 3 11 TJ 13 NA l PE RSCNNE L INJURIES 80 NUVdER O E SC R t 8 TICN lai l0l0;Ol@l 4 9 NA l 11 12 90 LOSS CF QR CAttAM TO FACr lTY NDE WCPIP *lCN i

t ,i I z q)l NA  !

uaJTv iSSUEOp OE!CRIPT!ON v e 78110R0l@- NRc usE cNtY

}

13I 6l NA J 3 to l ll ll!lI IlI!III 6d 63 30 3 NAME OF PREPARER ob Wd ciga X265 PHONE:

{

ATTACHMENT TO LICENSEE EVENT REPORT 76-072/03X-1 COMMONWEALTH EDISON COMPANY (CWE)

DRESDEN UNIT-2 (ILDRS-1)

} DOCKET # 050-237 i During routine startup operations, CRD J-11 was-found to uncouple and over-travel when withdrawn to position 48. An insertion to position 46 and sub-

, sequent withdrawal to position 48 showed the drive and the blade to be recoupled.

l CRD J-11 was again inserted and withdrawn to position 48, and again the over-i travel alarm annunciated, indicating that the blade and drive had uncoupled.

The drive was then inserted and withdrawn a third time to position 48 without incident. Recoupling was verified by cycling the CRD three times; no over-l travel alarm or loss of position indication resulted.

On 12/30/76 an on-site review determined that a loosened (unlatched) inner

l. filter could cause the blade and drive to uncouple at position 48. It was 1 .

also determined that the loosened filter could not exert sufficient pressure to uncouple the Blade except when the drive was fully withdrawn to position 48; upon insertion, the blade and drive automatically recoupled. Since the possi5111ty of uncoupling the blade existed only when the drive was withdrawn

} to position 48, CRD J-11 was considered to be operable. As a precautionary j -

measure, an operating order was issued to ensure that a coupling check was performed whenever drive J-11 was withdrawn to position 48. Should subsequent-uncoupling occur, immediate actionwould Be taken to ensure that the drive's .

j status complied with Tech Spec section 3.3.B.1.

Because the potential for uncoupling the blade existed only at position 48, the safety implications of this event were minimal. Control rod drive /b' lade uncoupling incidents had occurred several times in the past.

, As mentioned, symptom and performance evaluations indicated that a loosened inner filter could cause the Blade and drive to uncouple at the fully with-

, drawn position. Loosening of the filter could have resulted from a combination of improper installation and latching spring fatique.

7 On November 23,1977 CRD J-11 was disassembled and inspected per Control Rod

, ,' 9. % . Drive Inspection and Maintenance Procedure DMP 209. To assure.a~ comprehensive,. ,

j inspection a special operating procedure (SOP 216) inns prepared and ~ followed.

Upon inspection it was found that the inner filter was latched. However, the inner filter retaining ring was found bowed apart and galled which indicates l' that the inner filter was relatched during the recoupling process at power.-

In addition the distance Between the CRD flange'and the.end of the fully seated uncoupling . rod was abnormally long (173.406 + .0625") . The' abnormal length' coupled with an unlatched inner filter resulted in the uncoupling of the CRD

~

l, during normal operating conditions.

. 4 e

P i  !

1

- - L- - . -- - .- , . . . . . , . - . . . - , , - -,.

. u CRD J-11 had been overhauled in January,1975. Since May, 1975 a 20 to 30 pound pull test on the inner filter has been incorporated in the overhaul and reassembly procedure. Control Rod Drives overhauled and reassembled under this revised procedure have not experienced uncoupling. The revised procedure coupled with improved Quality Control Coverage of CRD overhaul and reassembly cre believed to be adequate to prevent future CRD uncoupling.

4 i

i e

l l

I I

- ~ w- .o -e .. . ,