ML20052E485

Updated LER 81-026/03X-1:on 810915,during Shutdown Process, Rod P-10 Showed Wrong Position on Rod Worth Minimizer.Caused by Diode Failure Resulting in Multiple Output Distributor Error Forcing Rod Block to Occur.Five Diodes Replaced

ML20052E485
Person / Time
Site:	Dresden
Issue date:	04/01/1982
From:	Schroeder B COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20052E481	List: ML20052E480 ML20052E485
References
LER-81-026-03X, LER-81-26-3X, NUDOCS 8205110149
Download: ML20052E485 (2)

Text

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LICENSEE EVENT REPORT REVISED REPORT cpNTROL SLOCK: l PREVIOUS REPORT DATE: 9/29/81 i

l l l  ! l l@ (PLEAss PmNT OR TYPE ALL REQUIRED INFOZMATIONI W lIlLlDlRlSl'*

7 8 9 uCENSEE CODE Q O l0 l-IS l 0 l 0 l 0 l 0 l0 l -l 0 l 0 l@l 4 l 1uCENSE I4 UCENSE hyMSER 2S 28 l1 l1Typgl 1l@l 40 l

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60 61 QOCKET NUMS ER 68 69 EVENT QATE 74 75 REPORT QATE 40 EVENT DESCRIPT!CN AND PROBASLE CONSECUENCES l o 121 l The unit was in the process of being s utdown when rod P-10 showed the wrong position on [

gg the rod worth minimizer (RWM). This caused rod-in and rod-out blocks from the RWM. Tne ;

,g,,, , RWM was placed in bypass and a second independent operator verified proper rod movement g g ,,, , so the shutdown could continue. All protective systems functioned properly and there was; no effect on public health or safety. This is the first event of this type. ,

1017] I I lo!ali I 7 8 9 80 CE CD su E COMPONENT COQE sus CQ'E su a lol91 7 8 lIlBlh d h W h lIlNlSlTlRlUlh lXlh d h 9 to 11 12 13 18 19 20

,,, SEQUENTIAL OCCURRENCE REPORT REVISION g ggfp0 EVENTvEAR R EPORT NO. COCE TYPE NO.

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8 l 1l l-l 10 12 l6 l l/l 10 l3 l lXl l,-d l ll 22 23 24 26 27 28 23 30 31 32 EEN 7CEEE oEPt Nr **"ES$o" u wovRs 22 *5e*MITTE#

s Pc"RIaS e. sEEuE uaNPAc"ERER l33A lgl34 Zl@ l Zl g 35 l36Zl@ 3Jl0 l0 l 0l l l N lg lN [g l N lg l Gl 0l 8l 0lg 40 41 42 43 44 47 CAUSE DESCRIPTION ANC CCRRECTIVE ACTIONS @

g i g o l l The cause was failure of one diode. This caused a multiple output distributor error thatl g,,,jg forced the rod-block to occur as a fail-safe measure. An additional five diodes were  ;

replaced on the printed ciruit boards (IDDAl'and IHBAl) of the RWM because they were ,

, , y near their design limits. Tests were satisfactorily conducted after replacement. No y further action required.

7 8 9 80 Arus %Powem OT14ER STATUS 08 O ERv OlsCOVERY CESCRIPT10N N/A l8 I5 l l Dl@ l 0l 0l 0l@l

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• a$nvify co'0 TENT 4e so

• ELEAsto or *ELEAsE LOCATION CP RELEASE @

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l l AMOUNT N/A OF "

ACTIVITY l

N/A l l PERSONNEL ExPosuEEs

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lhloEsCRimoN N/A h l etasoNNE'L iNau'dits

• NUMeER QEsCRiPTION lt lall0l0 7 8 9 l0[@l 11 12 N/A l 30 Loss 08 OR OAMacE TO PACluTY TvPE DEsCRIPTt0N N/A li 191 l Zlhl l

• UsusTv 8205110149 820401

• PDR ADOCK 05000249 NRC USE CNLY 121 o 1 [, N,,jhlCEsCRIMON issuto N/A S h PDR ]

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30. ;

B. Schroeder 815-942-2920, X-548 o NAME OF PREPARER P54CN E: g

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SUPPLEMENT TO DVR DVR NO. .

STA UNIT. YEAR NO. .

D- 12 - 3 . 81 . 53 PART l l TITLE OF EVENT OCCURRED Rod Worth Minimizer Failure During Shutdown 9-15-81 0235 DATE TIME REASON FOR SUPPLEMENTAL REPORT In Item 27, the cause of failure was changed to state that only one diode actually failed and to clarify the reason for replacement of five additional diodes.

PART 2 l . .

f t ACCEPTANCE BY STATION REVIEW \Q 8% /f// [A/

,w j DATE 3 4 2 L\ f(1--

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SUPPLEMENTAL REPORT APPROVED AND AUTHORIZED FOR DISTRIBUTION. S . ./ .5Np- Y / l'1/7L

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