[ RadSafe ] Fukishima Pu-239

[Peter Bossew]

>only a tiny, tiny fraction


indeed. Atmospheric Pu release from Fukushima (state of knowledge 2012):

http://www.sbpr.org.br/anais22.asp  

pb.




"The International Radiation Protection \(Health Physics\) Mailing List"
<radsafe at health.phys.iit.edu> schreibt:
>I suspect that it is largely a matter of what "more" means in this
>context: more per unit mass of fuel, more per operating hour, more per
>unit of energy produced, etc.  It also depends on whether you are taking
>about Pu-239 made or Pu-239 releasable/recoverable (not fissioned in  the
>reactor where it is created).
>
>You certainly can make Pu-239 with both heavy and light water reactors. 
>If you are looking to recover Pu for bomb making you want to be able to
>refuel online, because you don't want your fuel to "over cook", as Pu-240
>and Pu-241 both present problems in processing plutonium (but are of much
>less concern if you are planning to burn up the fuel in a reactor).  
>
>As to the release of Pu of any flavor from Fukushima: almost certainly. 
>How much and in what chemical form probably is still in the "anyone's
>guess" category, but it is quite reasonable to guess that it makes up
>only a tiny, tiny fraction of what has been released, whether measured by
>mass, atom, or activity.
>
>-----Original Message-----
>From: radsafe-bounces at health.phys.iit.edu
>[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Jaro Franta
>Sent: Friday, June 06, 2014 6:32 PM
>To: 'The International Radiation Protection (Health Physics) Mailing List'
>Subject: Re: [ RadSafe ] Fukishima Pu-239
>
>Actually, enriched fuel like Fukishima produces MORE Pu than a heavy
>water reactor using unenriched fuel, for the simple reason that the
>irradiation of enriched fuel is about five times greater.
>
> Jaro
>^^^^^^^^^^^^^^^^^^^^^^^^^
>
>
>
>
>
>-----Original Message-----
>From: radsafe-bounces at health.phys.iit.edu
>[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of
>sfisher373 at aol.com
>Sent: June-06-14 8:15 PM
>To: radsafe at health.phys.iit.edu
>Subject: [ RadSafe ] Fukishima Pu-239
>
>
>
>Pu-239 comes from the U-238 in the fuel.  So enriched fuel like Fukishima
>produces less Pu than a heavy water reactor using unenriched fuel.  
>
>
>
>The neutrons are thermalized in the fuel and cause the U-235 to fission.
>The ideal place for fissioning is on the outside of the fuel bundle. 
>Deeper in the neutrons have lost energy and are resonantly absorbed by
>the U-238.
>The U-239 fissions easier than the U-235 so any U-239 formed on the
>outside will fission.  However, burnup also depends on where in the
>reactor the fuel bundle is. So the statement that there is more Pu on the
>outside of the bundle rather than deeper in does not make much sense.  
>
>
>In Candu reactors about half the energy comes from the Pu-239 fissions. 
>One of the reasons why nuclear non proliferation groups do not like the
>CANDU reactor, along with on line refueling so it is theoretically easier
>to steal a bundle.  
>
>
>However, separating the isotopes from a spent fuel bundle requires more
>expertise than just enriching fuel.  
>
>
>Spencer M Fisher
>
>