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Ao:On 700605,turbine electro-hydraulic Control Sys Transient Caused Turbine Trip & Reactor Scram,Followed by Inadvertently Opened Safety Valves.Two Safety Valves Failed to Close,Releasing Primary Coolant to Containment
	ML20084T882
Person / Time
Site:	Dresden, 05000000
Issue date:	06/15/1970
From:	Brian Lee; COMMONWEALTH EDISON CO.
To:	Morris P; US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084T734	List: ML20084T789; ML20084T813; ML20084T820; ML20084T882; ML20084T899; ML20084T979;
References
	02053, 2053, NUDOCS 8306240240
	Download: ML20084T882 (4)
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, ONE F1RST NATIONAL P L A a. A

C H I C A G O. ILLINOIS \

Addr.n Rwly to:

POST OFFICE BOX 767

C H I C A G O, I L L I N O 15 60490 1

June 15, 1970 Dr. Peter A. .lorris, Director e Division of fleactor Licensing U.S. Atomic Energy Conaission Washington, D.C. 20545

Subject:

' License DPR-19, Dresden Nuclear Power Station Unit No. 2, Section 0.6. D.3 of the Technical Specifications

Dear Dr. .'torris :

The purpose of this letter is to report an abnormal occurrence in which a~ transient in the turbine electro-hydraulic control systen ccused a turbine. trip and reactor scram of Dresden Unit 2 on Friday, June 5, 1970 Following the reactor scram, the safety valves inadvertently opened, two of which failed to close fully resulting in the release of a snall amount of primary coolant to the prinary containnent. The safety systens functioned as required during the reactor scrau. ~

Dresden radiation protection procedures pere followed.

All drywell entries were made according to Dresden procedures and Continuing radiation surveys were perforood in the 10 CFR Part 20 drywell and through the plant. A bioassay program was started on selected individuals who had entered the drywell.

Preliminary results of environnental surveillance sampics collected after the event have not exhibited higher data in the dounuind quadrant from the plant than the data obtained upwind. On and off site Ionization Chanbers and on-site air particulate sample results were norual.

Initial action following the reactor scran verified that the reactor was in a sate shutdown condition with all control rods inserted and the reactor core covered with water. -

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1)r , Peter A. Morris June 15, 1970 i

A review of this occurrence is currently underway with j General lilectric Company personnel. The I)ivision of Compliance, Region III, is naintaining close contact with the progress of the review. h' hen the review is completed, Connonwealth F.dison will report the findings of the review with the Division of Reactor Licensing. h'c uill schedule this revicu uith you before our present maintenance outage is completed and prior to startup of the unit.

Very truly yours,

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l Byron Lee, Jr.'

Assistant to the President i

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.occdrrenco'in which a trangientThe in .thepurpose turbine c1cetro-hydraulic- of this letter is to re' port an abnor '

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. control systen caused Unit 2 on Friday, June a5,tutbine 1970 trip and reactor scram of Dresden -

Following the reactor scram, the -

saf'ty valves inadvertently opened, two of which failed to close fully to theresulting primary containnent. in the release of a snall amount .of primary coolant .

required during the reactor scrau.The safety systems functioned as Dresden radiation protection procedures perc followe'd. " .

- A11cdrywc11,entrics 10 CFR.Part 20 were made according to Dresden; procedures and 4

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ML20084T882

Text

Subject:

Dear Dr. .'torris :

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