Re: MOX Program

["Ron L. Kathren" <rkathren@tricity.wsu.edu>]

Jaro --

I stand corrected -- that's what happens when you are old enough (as am I)
to have taken freshman physics from Newton!  Your clarification was exactly
what was needed and I think we can agree (and I will revise my comments) to
read that it is a practical impossibility (whatever that is!).

Ron


----- Original Message -----
From: Franta, Jaroslav <frantaj@aecl.ca>
To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
Sent: Wednesday, August 23, 2000 3:25 PM
Subject: RE: MOX Program


>
> Ron, Group,
>
> Its not that simple, unfortunately.
>
> While its true that "Pu-240 is not fissile," this only means it can not
> support a thermal neutron chain reaction. But Pu-240 CAN support a FAST
> neutron chain reaction (neutron energy ~ 0.5 to 4 MeV). This is quite
unlike
> U-238, which can't do either (but is called fissionable, because it can be
> fissioned by VERY fast neutrons - like those from hydrogen fusion
reactions,
> i.e. energy > 4MeV). For that reason, a new term has been coined for
> nuclides like Pu-240 (which also includes Pa-231, Am-241 and Np-237),
dubbed
> "fissible."
>
> I think that Jacques Read said it best when he wrote that "It is
> theoretically possible to drive any fissile material to super-criticality
if
> you use enough chemical high explosive to compress it, but the fission
> density suffers and the resulting object doesn't give a big multiplier
over
> the same weight of TNT." ...its just that he was being a bit liberal with
> his usage of the word "fissile" (am I right, Jacques ?).
>
> Its very educational to view the differences in fission x-sections as a
> function of neutron energy. You can do this by going to an interactive
> nuclear x-sections database like the one at JAERI, and plotting out the
> x-section curves for these nuclides.
> The web site is at
> http://wwwndc.tokai.jaeri.go.jp/Figs/endfplot.html
>
> For your convenience, I have prepared one such graph, with the following
URL
> - which I'm hoping you can manage to stuff into your web browser address
> line - let me know if it works... it worked when I clicked on the URL in
> this message, but it will get chopped up in the Radsafe posting & will
need
> to be reassembled on your web browser address line; also, give it a couple
> of seconds before the graph appears -- the first display is the input
page,
> which then automatically switches to the plot... in the worst case, I can
> always just send you the picture to your personal address) :
>
http://wwwndc.tokai.jaeri.go.jp/cgi-bin/w3endf/?lab=Pu239%3BPu240%3BU238&mt=
>
Pu-239%3D18%2FPu-240%3D18%2FU-238%3D18&ax=log&e0=50000&e1=4000000&ay=log&y0=
> 0.0001&y1=10&sx=&sy=
>
> PS. my offer of an AVI color animation illustrating the real problem in
> making RGPu bombs, called "Mark's RGPu dud," still stands (it was
initially
> made in a Radsafe post of Wednesday August 16, 2000 2:43 PM), in case you
> are interested.   BUT PLEASE DON'T reply on RADSAFE - contact me
personally
> at frantaj@aecl.ca
>
> Regards
>
> Jaro
>
> -----Original Message-----
> From: Ron L. Kathren [mailto:rkathren@tricity.wsu.edu]
> Sent: Wednesday August 23, 2000 5:00 PM
> To: Multiple recipients of list
> Subject: Re: MOX Program
>
>
> Pu-240 is not fissile; it cannot therefore support a chain reaction and
> cannot be made into a nuclear explosive.  It is physically impossible to
> make a bomb with Pu-240, unless there are some new laws of physics.
>
> Ron Kathren
>
>
> ----- Original Message -----
> From: William Prestwich <prestwic@mcmail.cis.McMaster.CA>
> To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
> Sent: Wednesday, August 23, 2000 6:50 AM
> Subject: MOX Program
>
>
> > The MOX program is being criticized as not fulfilling its purpose
> > of rendering the fuel unusable for nuclear weapons. The Carson Mark
report
> > is quoted as stating that any mix of Pu isotopes may be used to make a
> > weapon. I know there were excellent postings on this subject-I am sorry
to
> > say I haven't yet found out about going to the archives. But the above
> > statement would imply in the extreme that a weapon could be made using
> > pure 240Pu-is that really possible?
> > If anyone has the time, could they please enlighten me directly,
> > unless they feel their comments are beneficial to the community at
large.
> > Thanks,
> > Bill Prestwich
> > McMaster University,
> > Hamilton, Ont.
> > E-mail: prestwic@mcmaster.ca
> >
> > ************************************************************************
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