ML20196L578

Ack Receipt of Discussing Info Notice 88-021 on Inadvertent Criticalities.Discovery of Three Repts Dealing W/Three Events Mentioned in Ltr Noted

ML20196L578
Person / Time
Site:	Millstone, Peach Bottom, Fermi, Vermont Yankee, Quad Cities, 05000000
Issue date:	06/16/1988
From:	Rossi C Office of Nuclear Reactor Regulation
To:	Hanauer S TECHNICAL ANALYSIS CORP.
References
IEIN-88-021, IEIN-88-21, NUDOCS 8807080020
Download: ML20196L578 (2)

Text

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• • • .* JUN 161988 Mr. Stepts H. Hanauer Senior Vice President Technical Analysis Corporation 6723 Whittier Avenue, Suite 202 McLean, VA 22101

Reference:

Letter from S. H. Hanauer to C. E. Rossi dated May 16, 1988

Dear Steve:

Thank you for your letter discussing Information Notice 88-21 on inadvertent criticalities. We do consider the three events discussed in the notice to b.)

special cases. The notice was limited to cases in which the operators never intended to go critical during the evolution that led to the events. We believe that these are the types of events where the plant staff might be more apt to disable the trip system, since they would believe that there was no possibility' of going critical. Also, an inadvertent criticality in these situations is especially significant since much of the necessary preparation for plant start-up, such as vessel head installation and systems checkout, may not have been performed. As far as we can determine the Vermont Yankee and Millstone events discussed in the notice are the only ones that have occurred at U.S. reactors that fit this category.

We were able to find reports dealing with three of the events that you men-tioned in your May 16 letter.

During the Femi 2 event on July 2,1985, the reactor was undergoing a planned startup when the operator, failing to follow procedures, moved the rods through the critical position and then reinserted them when he noticed the power in-creasing unexpectedly. This event raised additional concerns at the time because it was not reported until July 15.

At Quad Cities Unit 2, the operators were attempting to demonstrate sub-criticality during preparations for reactor startup on February 17, 1984.

The reactor was supposed to remain suberitical at position 24 on the third rod. However, when the rod was raised to position 18, the reactor went critical and the rods were reinserted.

The March 18, 1986 event at Peach Botton also occurred during a planned startup. As you indicated, the rod worth minimizer was not operable and the rod sequence control system was deliberately bypassed. The reactor had reached 3% power when the operators realized that the rods were out of sequence and 3 scrammed the reactor. lh f) &) Y 8807080020 880616 5 PDR ADOCK 0500 9

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393 1 6 1888 Mr. Steven H. Hanauer We were not able, during our limited search, to locate any information on the 1977 Peach Bottom event.

Sincerely,

\9 Charles E. Rossi, Director Division of Operational Events Assessment Office of Nuclear Reactor Regulation DISTRIBUTION TTMartin, NRR CERossi, NRR CHBerlinger, NRR DCKirkpatrick, NRR WDLanning, NRR MKing (88-65)

NKing-Wertman (88-62)

PDR Central- Files '

DCS DOEA R/F 0GCB R/F DKirkpatrick R/F

• SEE PREVIOUS CONCURRENCES

• 0GCB:DOEA:NRR *C/0GCB:00EA:NRR .P, DKirkpatrick CHBerlinger CER i 06/06/88 06/06/88 6//J88

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