Re: Japanese nuclear accident: Did the reaction oscillate?

[Michael McNaughton <mcnaught@lanl.gov>]

At 06:00 AM 11/29/99 -0600, you wrote:
>My quetion is: How can a neutron dose rate be sustained at 
>approximately the same level for hours after a criticality accident?

My limited understanding is as follows.
1. The intitial criticality causes a large release in energy; this causes
bubbles to form in the water; the bubbles increase the volume so the system
becomes subcritical.
2. After a time (on the order of 10 seconds) the bubbles collapse and there
is another criticality pulse, smaller than the first pulse; again, bubbles
are formed, but smaller than the first time. 
3. The cycle repeats several times causing several pulses per minute. The
amplitude gradually decreases as the energy released becomes smaller and
the bubbles become smaller. Eventually, a steady state is reached.

mike
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html