Japanese nuclear accident: Did the reaction oscillate?

["Bjorn Cedervall" <bcradsafers@hotmail.com>]

Several early information sources about the Japanese nuclear accident said 
that the nuclear reaction oscillated. I find this puzzling when looking at 
the neutron dose rate measurements in the surroundings (IAEA report a few 
weeks ago). My quetion is: How can a neutron dose rate be sustained at 
approximately the same level for hours after a criticality accident?

I realize that there may be (if so, probably a very small fraction of) 
radionuclides that emit neutrons after a fission event - but if so - which 
ones would they be? Or was it an accident where - after the initial Cerenkov 
flash - the nuclear reaction was continuing in some more balanced mode? (I 
assume that the neutron dose rate measured in the surroundings outside the 
building essentially came from the direct source - rather than from any 
released, minor fission product).

As the information stands I question the oscillatory mode description.

Please comment or clarify my thoughts here,

Bjorn Cedervall   bcradsafers@hotmail.com

______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html