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RE: Errors in NRC TMI Factsheet
Norm Cohen passed along a farrago of mis-information. I'll comment in an area I know quite a bit about:
-----Original Message-----
From: Norm Cohen [mailto:ncohen12@comcast.net]
Sent: Sat 3/6/2004 3:07 PM
To: unplugsalem@yahoogroups.com; Know_Nukes@yahoogroups.com; radsafe@list.vanderbilt.edu
Cc:
Subject: Errors in NRC TMI Factsheet
What?s Wrong With the NRC?s 2004 Fact Sheet on the TMI Accident?
Published by
Three Mile Island Alert - March 2004
(NRC Fact sheet available at
http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html)
<snip>
It was only by luck that the reactor walls were not breached. The industry
conjectured that voids in the coolant prevented molten fuel from burning
through the reactor walls. It is not known if these voids will form to
prevent
a total meltdown in future accidents. Fifteen million curies of
radiation is a
?massive quantity.?
<snip>
===================
It was actually not luck, but a previously unanalyzed aspect of heat transfer during the accident.
As the molten core materials (corium) dropped into the lower reactor vessel head, it contacted the relatively cool lower RV head and froze. The frozen corium was a mixture of metals and metal oxides (mostly metal oxides). As such, it was a ceramic material and had a relatively low heat transfer coefficient. The molten corium was enclosed in a "cup" of frozen corium. The small flow of heat through the frozen corium was easily conducted to the outside of the lower RV head by the metal in the head (which has a high heat transfer conductivity). This combination of low heat flow through the frozen corium and easier heat flow through the metal head kept the temperatures in the head low enough to prevent melting.
This previously unanalyzed phenomena is being incorporated into the design of next generation reactors as a passive safety feature. It has been thoroughly analyzed by reactor vendors and others and accepted by the NRC during its review of the new designs.
Best regards.
Jim Dukelow
Pacific Northwest National Laboratory
Richland, WA
jim.dukelow@pnl.gov
These comments are mine and have not been reviewed and/or approved by my management or by the U.S. Department of Energy.
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