AW: [ RadSafe ] Californium vs. Americium

[Franz Schönhofer]

Mike,

I agree, that Pu-238 might be a better choice, but I know for sure, that
Po-210 has been used together with Beryllium as neutron source in nuclear
bombs and in nuclear reactors to start the chain reaction. Po-210 was and
still is produced by neutron irradiation of Bi-209 (naturally occurring).
Natural occurring Po-210 in uranium ores is only abundant in minute amounts
and you might know, that Marie Curie had to use many tons of pitchblende
residues to isolate it and you might know that she called it polonium
because her native country was Poland (which then for a long time did not
really exist). 

Additional hints: When the nuclear reactor at Windscale, England burnt in
Oktober 1957 also large amounts of Po-210 were emitted - the reactor was
also used to produce Po-210 and this is very volatile. 

I do not believe, that nuclear bombs are stored fully assembled and several
occasions confirm my belief: Several accidents are known (e.g. Palomares,
Spain and Thule, Greenland) where nuclear bombs fell to the ground from
airplanes. It was always communicated, that these bombs had not been armed.
In the reports about the nuclear bombs exploded over Hiroshima and Nagasaki
there was always mentioned that the bombs were armed during flight. In the
excellent book "Picturing the Bomb" about the Manhattan Project it says,
that the bomb was finally assembled during flight. It would not be a good
idea in the light of the now prevailing concerns in the USA about terrorism
not to inherently secure the bombs by not having them fully assembled. 

Another hint is, that polonium is still produced. I do not believe that the
Po is still widely used as a static eliminator, so what should the
production otherwise be good for? 

BTW replacement of the extremely poisonous Po-210 by plutonium (238) would
be of occupational health significance, though our green friends always
claim that plutonium is the deadliest substance on this world. No, its
Po-210!

Some information I found confirmed by using at Google "neutron sources
polonium".

Best regards,

Franz

Franz Schoenhofer, PhD
MinRat i.R.
Habicherg. 31/7
A-1160 Wien/Vienna
AUSTRIA


-----Ursprüngliche Nachricht-----
Von: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] Im Auftrag
von Brennan, Mike (DOH)
Gesendet: Donnerstag, 28. Juni 2007 23:21
An: radsafe
Betreff: RE: [ RadSafe ] Californium vs. Americium

Hi, Franz.

Are you sure it isn't Pu-Be rather than Po-Be?  I am sure that one could use
Po-210 and make a compact source with high output, but the 140 day half life
means that you would have to use it quickly, before it decayed too much.
That doesn't sound too good for nuclear weapons, that usually are left
inside their delivery systems for many years at a time.  Pu-238, on the
other hand, has a really nice half life for doing all sorts of things where
you want to balance specific activity and longevity.  

Though both Po-210 and Pu-238 are good from the point of view of not having
screaming hot gammas, which I understand was the biggest problem with RaBe
sources. 

-----Original Message-----
From: Franz Schönhofer [mailto:franz.schoenhofer at chello.at] 
Sent: Thursday, June 28, 2007 1:52 PM
To: Brennan, Mike (DOH); 'radsafe'
Subject: AW: [ RadSafe ] Californium vs. Americium

Mike (and others interested),

Far from being an expert on neutron sources I remember that Cf-252 is used
as a single source of neutrons because of spontaneous fission - as you
pointed out. I never heard that its alpha-particles were used to generate
neutrons together with Be. 

Po/Be neutron-sources have been and are obviously still used in nuclear
reactors and in nuclear bombs. 

The first neutron-sources were obviously Ra-Be mixtures. I doubt they are
still used.

Using DU as a source for alpha-particles would - if it were possible - not
reduce the quantity of DU stored significantly.....