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Re: [Phys-l] recriticality at Fukushima




In a message dated 11/3/2011 1:40:20 P.M. Eastern Daylight Time,
jsd@av8n.com writes:

On 11/03/2011 09:45 AM, Jeff Radtke wrote:
Cf-252 has a half life of 2.6 years, and 3% of these decay events are
spontaneous fissions.

Right.

As of today, Tepco has figured this out, and has retracted the
announcement about recriticality.

As of yesterday, they had definitely not figured it out. They
were dumping boron onto the reactor, in an effort to stop the
"reaction". This proves they were taking the recriticality
issue seriously.

This leaves us with a couple of minor mysteries, such as why
they observed xenon recently but not earlier ... and why they
didn't know how to interpret the xenon observation when they
did get it.






Cf 252 is likely produced from neutron bombardment of plutonium during
power operations and does in part decay by spontaneous fission.It also
undergoes alpha decay. When I heard about the claims of re criticality I was
surprised, these cores have only 3% enriched Uranium , but they would have
significant plutonium, so who knows. The Cf-252 explanation makes more sense.

Bob Zannelli