ML20236F121

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PNO-76-190:on 761112,while Performing Shutdown Margin Test Following Partial Refueling of Reactor,(Head Off) Inadvertent Reactor Criticality Occurred.Event Caused by Operator Error
ML20236F121
Person / Time
Site: Millstone Dominion icon.png
Issue date: 11/12/1976
From: Dreher F, Roy G, Thompson D
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
To:
References
PNO-76-190, NUDOCS 9807020033
Download: ML20236F121 (1)


Text

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_s PRELIMINARY NOTIFICATION v ~

November 12, 1976 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-76-190 This preliminary notification constitutes EARLY notice of an event of POSSIBLE safety or public interest significance. The information presented is as initially received without verification or evaluation and is basically all that is known by IE staff on this date. '

N Facility: Millstone Point Unit 1 Subj ect: SHUTDOWN MARGIN TEST - INADVERTENT CRITICALITY {

At 4:50 a.m. on November 12, while performing a shutdown margin test following the partial refueling of the reactor, (head off) an inadvert-eut reactor criticality occurred. The event was caused by operator error when the operator selected an adjacent control rod to the al-  !

j ready withd: awn rod instead of the specified diagonally opposite rod. '

The licensee reported that no personnel overexposure occurred, nor was there any equipment malfunction or damage resulting from the criticality.

All safety interlocks and controls were reported to be operational at the time of the event. The reactor safety circuits scrammed on the resulting flux increase.

A reactor inspector was dispatched and is at the site. An investi-gator and health physics inspector were dispatched from the office.

Media interest is expected because of ongoing attention to events at this facility. The State of Connecticut has been and is being kept informed. A press release is planned.

Region I, NRC, Philadelphia, Pennsylvania received notification of this occurrence by telephone from the licensee at 8:35 a.m., November 12, i 1976. I

Contact:

FADreher, IE x27261 GWRoy, IE x27261 DThompson, IE x27541 Distribution:

Chairman Rowden Commissioner Mason S. J. Chilk, SECY Commissioner Gilinsky C. C. Kammerer, CA G. F. Murphy, JCAE Commissioner Kennedy L. V. Gossick, EDO E. Volgenau, OIE J. A. Harris, PA B. C. Rusche, NRR H. K. Shapar, ELD T. J. McTiernan, AIA K. R. Chapman, NMSS R. G. Ryan, OPS Transmitted: PBldg  ; H St.  ; MNBB  ; Luge  ;

PRELIMINARY NOTIFICATION 9807020033 761112 PDR I&E PNO-76-190 PDR

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