ML20084D816
| ML20084D816 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 09/25/1970 |
| From: | Hoyt H COMMONWEALTH EDISON CO. |
| To: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8304120432 | |
| Download: ML20084D816 (2) | |
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Commomvealth Edison Company ONE fr I R S T N A T IO N A L PLAZA
- C H I C A G O.
BLLINOIS Addren tenir se:
POST OFFICE BOX F47
- C H I C A G O, Ilt lH OIS 40490 Dresdon I:uclear Pouer Station
! rr5.s Illinois 60450
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- >...,y'S Sojtenbor 25, 1970
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.'g Dr. Zeter
't. Morris f.Ff G li g};-lJ Division of 2eactor Licensing U. 3. Atonic harry Co:nission jl Usshington, D. C. 20545 y
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Licenso 2:~a - 19, Dresden 1:uclear Power atation Unit 2, Section 6.6.C.1 of the Technical Specifications.
Dear 1:
- r..: orris This is to report a condition relating to tho operation c,f the station in uhich control rod drives exceeded the 7.03 second macinum insortion t,im as required for 90ls insortion as specified by section 3 3.C.2 of the technical specifications.
Problen. Investi~ation and Corrective Actinn A roviou of scran ti-ing traces on the 29 monitored drives du-ing a scram on September 11, 1970 revoal d that ono drive had a scran tL.o of 2.S5 coconds for 50,' insertion.
As a result of this infornation individual drivo scran tests woro perforned in the power operating condition botucon Septenber 15 and 19, 1970.
Analysis of the individual drivo scran data rovcaled that two drives had tines excoeding 7.C0 secoads for 90,2 insertion.
Those tuo drives,G____9 (99.! innertion tine = 12.62 seconds) and Q_,_2 (900 insortion tino:' 8.61 seconds), uero olectrically disarmed and cbclared inoperable.
In accordance with our letter to you of Docenbor 15, 1969, signed by ietor J. Van:: ort we have tabulated below all drives excooding 3.6 seconds for 90;; insertion.
The averazo scrau ti.ce for all operable control rod drives is now 2.69 sceands.
The tuo control rod drives with excossivo scran ti es were roplaced during the maintenance outage which began Septenbor 23, 197C.
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EO 8304120432 700925 c
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o7 Control Rod Time in Seconds (Data taken 9/15 to 9/19/70)
Drivo 10I 50 S d
Insertion G-9 1.00 6.25 12.62 G-7 0 50 4.14
.8.61 J-9 0 50 3 24 6.71 F-1 0.42 1 79 3 67 Very Truly Tours, k'
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H. K. Hoyt Superintendent
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