ML20092P626

Confirms Util Commitment to Fully Investigate 840623 Event in Which Six Control Rod Pairs Failed to Insert Into Core Under Automatic Velocity Limited free-fall Sys.Nrc Approval of Resolutions Will Be Obtained Prior to Reactor Startup

ML20092P626
Person / Time
Site:	Fort Saint Vrain
Issue date:	06/26/1984
From:	Lee O PUBLIC SERVICE CO. OF COLORADO
To:	Johnson E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
P-84188, TAC-55294, NUDOCS 8407090187
Download: ML20092P626 (1)

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4 l jk PUBLIC SERVICE COMPANY OF COLORADO ()'

l P. O. BOX 840 DENVER, COLORADO 80201 OSCAR R. LEE 16805 WCR 19 1/2, Platteville, Colorado 80651 l V8 ',E PR ES' D E** T l

June 26, 1984 Fort St. Vrain Unit #1 Mr. E. H. Johnson, Chief bb$Nb -

Reactor Projects Branch 1 Region IV Nuclear Regulatory Commission gggg 611 Ryan Plaza Drive, Suite 1000 '

p Arlington, TX 76011

SUBJECT:

Malfunction of Fort St. Vrain Control Rods To Automatically Insert Following Scram

Dear Mr. Johnson:

As you are aware, an event occurred at Fort St. Vrain during a  :

reactor scram transient on June 23, 1984, in which six control rod pairs (from Regions 6, 7, 10, 14, 25, and 28) failed to insert into the core under the automatic velocity limited free-fall system.

Appropriate actions were taken by control room operators to manually drive the affected control rods into the core after discovery of the situation, and all control rods were fully inserted within 20 minutes following the automatic scram signal.

Calculations have verified that cold shutdown conditions were achieved and maintained before manual insertion of the six affected control rod mechanisms. Additionally, the reserve shutdown system, totally independent of and redundant to the control rod system, was fully operational and available.

This letter serves to confirm Public Service Company's commitment to fully investigate this event, examine all six of the affected control rod mechanisms, and obtain Nuclear Regulatory Commission approval of ensuing resolutions prior to reactor startup.

If you have any questions or require any further clarifications, please contact Mr. Don Warembourg or Mr. L. M. McBride of my staff.

Very truly yours, 8407090187 840626 PDR ADOCK 05000267 PDR 0. R. Lee -

S l

l Vice President ctric Production )b ORL/djm

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