ML20084T899

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Ro:On 700605,turbine Tripped & Reactor Scram Occurred.Caused by Spurious Control Sys Signal.Following Reactor Scram, Safety Valves Inadvertently Opened.Two Valves Failed to Close Fully Releasing Primary Coolant to Containment
ML20084T899
Person / Time
Site: Dresden, 05000000
Issue date: 06/12/1970
From: Brian Lee
COMMONWEALTH EDISON CO.
To: Morris P
US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084T734 List:
References
1837, NUDOCS 8306240255
Download: ML20084T899 (1)


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"l Commonwealth Edison Company ONE F1RST NAT10NAL PLAZA
  • CHICAGO. ILLINOIS m.,a.a, POST OFFICE BOX 747
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Dr. Peter A. Morris, Director Division of Reactor Licensing flfd[Q.. -

U.S. Atonic Energy Connission Washington, D.C.

20545

Dear Dr. Morris:

Knowing of your interest in these matters, I an writing to advise you of a spurious turbine controlsysten signal which caused a turbino trip and reactor scram of Dresden Unit 2 on Friday, Junc 5, 1970.

Following the reactor scram, safety valves

' inadvertently opened, two of which failed to fully close resulting linthereleaseofasna11amountofprinarycoolant to the

,containnent.

Safety systems functioned as required during the reactor scran.

No release of radioactivity to the environment in excess of that permitted by the Technical Specifications occurred.

A preliminary review of the environs sampling stations indicated only normal background Icycls.

In accordance with the Dresden 2 Technical Specifications, we notified Region III Compliance within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

We intend to keep the Division of Reactor Licensing informed of the progress of our review which currently is underway with General Electric Company personnel.

iihen the above review is completed, Connonwealth Edison will discuss the findings of this review with the Division of Reactor Licensing.

No will schedule this review with you before our present maintenance outage is com-plcted and prior to startup of the unit.

8306240255 72030s Very truly yours, PDR ADOCK 05000237 S

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