Re: Japanese nuclear accident: Did the reaction oscillate?

["Michael Kay" <makay@teleport.com>]

The OKLO reactor did oscillate when it was active, however, that was about
2.3 billion years ago. The decay of the U-235 since then brought the system
to a point where it could not go critical with water moderation.

Michael A. Kay, ScD, CHMM
makay@teleport.com
----- Original Message -----
From: <Kerembaev@cs.com>
To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
Sent: Monday, November 29, 1999 9:21 PM
Subject: Re: Japanese nuclear accident: Did the reaction oscillate?


> Douglas,
>
> Do not forget the natural phenomena in South Africa.
> That reactor has been around for a while and as far as I know, it is still
> sustaining fission.
> Emil.
> kerrembaev@cs.com
>
> In a message dated 11/29/99 7:42:31 Pacific Standard Time,
> Douglas.Minnema@ns.doe.gov writes:
>
> <<
>  Bjorn and others,
>
>  Your are quite correct.
>
>  Depending on the initial conditions, a criticality accident can indeed
>  oscillate for some time period until the system thermally equilibriates,
and
>  then it can achieve a quasi- steady state mode of operation, which is
>  exactly what seems to have happened in Japan.
>
>
>  Note that this is also what happened in the Russian criticality accident
of
>  1997 with the metal system.  There was no liquid, and the heat losses
were
>  sufficient to not allow the fuel to heat up to melting; consequently the
>  system operated until it was physically dismantled by a robot after a
couple
>  of days.
>
>  A very simple but effective model for this type of system is the
>  point-reactor kinetics equations, which can be found in most nuclear
>  engineering text books.
>
>  Hope this helps,
>
>  Douglas M. Minnema, PhD, CHP
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