ML20128C090

Forwards Suppl Info on Util SG Tube Rupture Analysis Submittal of 920428

ML20128C090
Person / Time
Site:	Millstone
Issue date:	01/29/1993
From:	Rooney V NRC
To:	West G NRC
References
NUDOCS 9302030308
Download: ML20128C090 (3)

Text

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qgq Pb4 January 29, 1993 Millstone 3, 50-423 NOTK_TO: Garmon West. HilFB FROM: Vernon Rooney, Millstone 3 PM j, -

CUIUECT: SUPPLEMENTAL INFORMATION ON S/G TUBE (RUPTURE ANALYSIS SUBMITTAL OF 4/28/92

====================================================

By reiephone discussion with Ravi Joshi of Northeast Nuclear Energy

• /om v.in y we learned that the operator action time to initiate SI t ermination should be 3.30 minutes when correctly calculated rather than J minutes as reported in Table 1 of the 4/28/92 submittal. By

' el ephone dieeussion on 1/29/93 Joshi informed us that corrections

hould 91so be applied to:

t i n.e to identify & isolate 15.5 min. rather than 16.5 min, the ruptured steam generator

.iperstar action time to 1.48 min. rather than 3 min.

ini' late depreesurization Al* hough the rounding off of operator action time to initiate SI

++rminstion is slightly nonconservative, the net effect-of all of t 1 -e e e corrections is to reduce the total time from S/G tube rupture te 31 termination by 137 seconds, which is an improvement. These

-orrectiene do not affect any conclusions.

Ahl f axed me the at.tached table showing the corrected sequence of

-m nt:.

Enclorure: As stated

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Millstone Unit 3 Four Loop Operation i-Steam Generator Tube Rupture D 1

Margin to Overfill Analysis i TABLE 2 SE00 ENC [ OF EVENTS EVENT Time (sec)

SG Tube Rupture 0 ,

Reactor Trip 110 51 Actuation 338 '

Ruptured SG isolated i t . f ; -+

992 932 a- "'M * *T g

• As RCS Cooldown Initiated C ' * ' "

1476 pi t y RCS Cooldown Terminated 2300 3 -.es 7239 -- g.ga * *s RCS Depressurization Initiated 2484 73n .

RCS Depressurization Terminated 2612 21W N 3, , y ,y 3 wwi SI Terminated .3 d d b d 2794 W.67 /

Steam Relief to Maintain RCS Subcooling 3420 Break flow Terminated 4040 nd cbqc.

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t l-l WP0519:lD/080891 21