ML20136E264

Discusses 851226 Loss of Integrated Control Sys Event at Facility.Incident Investigation Team Will Investigate Event & Issue Rept within 45 Days

ML20136E264
Person / Time
Site:	Rancho Seco
Issue date:	12/31/1985
From:	Dircks W NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO)
To:	Asselstine, Palladino, Roberts NRC COMMISSION (OCM)
References
NUDOCS 8601060479
Download: ML20136E264 (2)

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UNITED STATES

~,t NUCLEAR REGULATORY COMMISSION h

WASHINGTON, D. C. 20555 DEC 311985 S o 3/L MEMORANDUM FOR:

Chairman Palladino Commissioner Roberts Commissioner Asselstine Comissioner Bernthal Commissioner Zech FROM:

William J. Dircks Executive Director for Operations

SUBJECT:

INVESTIGATION OF DECEMBER 26, 1985 EVENT AT yANrHO 9FCO WILL BE CONDUCTED BY AN INCIDENT INVESTIGATION TEAM (IIT)

At about 4:15 a.m. on December 26, 1985, Rancho Seco experienced a loss of the Integrated Control System (ICS).

Subsequently, the reactor tripped on high pressure and a severe overcooling transient occurred. Other equipment failures and personnel errors occurred. A radioactive release within technical specifi-cations also occurred. An adequate subcooling margin was maintained throughout the event and the plant is now in cold shutdown.

Because of the potential significance of the event, an NRC Augmented Inspection Team (AIT) was sent to the site on December 27 and started transcribed personnel interviews on December 28. The initial results of this investigatory effort has indicated that this event is complex and has potentially significant generic implications. Consequently, I have directed that the investigation be upgraded and that an Incident Investigation Team (IIT) be established.

This IIT is to:

(a) fact find as to what happened; (b) identify the probable cause as to whf 'it happened; and (c) make appropriate findings and conclusions which would form the basis for any necessary follow-on actions. A specific focus of the team will be on the design and response of ICS, and operator performance and training as they related to the loss of ICS during the event.

The team will report directly to me and will be led by Mr. Frederick Hebdon, l

Chief, Program Technology Branch, AE0D. Other team members include:

i J. T. Beard, NRR; R. Eaton, NRR; H. Bailey, IE; and G. Edison, NRR. The team was selected on the basis of their knowledge and experience in the fields of l

reactor systems, reactor operations, human factors, and instrumentation and control systems.

l The licensee has agreed to a request by Jack Martin, Regional Administrator, to preserve the equipment in an "as-found" state until the licensee and the NRC Team have had an opportunity to evaluate the event. The licensee has also agreed to maintain the plant in a shutdown condition until concurrence is received from the NRC to return to power.

8601060479 851231 PDR ADOCK 05000312 S

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4 The Commission ;

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The IIT report will constitute the single NRC fact-finding investigation f

~ report.

It is expected that the team report will be issued within 45 days from now.

gip::D Yliniau[Did4 h

William J. Dircks Executive Director for Operations j

cc: SECY c

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j OGC i

ACRS i

OPA i

. Regional Administrators i

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Distribution:

i DCS R. Minogue F. Hebdon E

AE00 CF J. Davis W. Lanning i

AE0D SF J. Fouchard PDR W. Dircks C. Kammerer

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Roe' J. Shea l

T. Rehm E. Jordan j

V.'Stello B. Faulkenberry l

i J. Sniezek ED0 R/F H. Denton C. J. Heltemes i

J. Taylor T. Ippolito

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Region V concurred via telecon 12/30/85.

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AEOD:D EDO i_____:____________:_____g,_":____________:___________.:.___________:.__..____.:......_____

]NAME:CJHeltemes:cg'WJ0ircks' 4..___:_..__.....:___.__._____:___________:____________:-___________:___..___.:__________

i DATE : 12/30/85

/ 7' /fr/85 i

0FFICIAL RECORD COPY i

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