[ RadSafe ] Fast neutron reactors, sodium etc.
JPreisig at aol.com
JPreisig at aol.com
Sun Jul 31 17:43:08 CDT 2011
This is from: _jpreisig at aol.com_ (mailto:jpreisig at aol.com) .
Hope you all are well and are enjoying barbecue season or whatever.
Fall earthquake season is upon us (hurricane season in the USA
also): Sept. 21, 2011
+/- 6 weeks. Earthquakes (magnitude 7.5 or above): about 2. Earthquake
Japan, Tonga/Kermadec, Taiwan, Indonesia.
Back to radstuff. Bless the crews of the Scorpion and the
Thresher. They gave their all.
Sodium metal in a submarine (surrounded by all that ocean water) would make
me nervous too.
Kudos to the Chinese for making that fast neutron reactor work on land.
So, when fast neutrons hit a hydrogen atom or molecule, they give
up much of their
incident energy. And when fast neutrons hit sodium atoms (or something
equally heavy), they
bounce off the heavy atom and don't lose that much of their incident
energy. So, sodium, if
heated somewhat is a good choice for the moderating fluid in a fast neutron
reactor. Still, heating
sodium makes me nervous also. Do I really want hot sodium metal in my
fast neutron reactor,
with 95% enriched uranium (enriched in U235) --- do I want such a reactor
that will be taking
a space crew to Mars or whatever???
How about using another material of similar heaviness (i.e atomic
Mineral oil??? Glass microspheres (SiO2) suspended in some water, iron
spheres suspended in some
water, any other suggestions???? I suspect mineral oil is a bad choice
because it will or could
break down upon neutron irradiation??? Can glass and/or iron small
spheres remain in suspension
in water and also be pumped through a reactor primary loop (a pipeline as
Clearly, you need more glass or iron in such a slurry to keep the fast
Someone having MCNP (Monte Carlo Neutral Particle Program} handy (or
someone willing to
do a crude hand calculation) could probably tell us if alternatives to
sodium metal would work.
Otherwise I'll eventually get to this problem via a big money research
grant (guffaw and snickering
noises go here???).
Whose bright idea was it to drill holes in the FFTF reactor core???
Guess we'll have to buy
or order a whole new reactor. Oh, don't let me leave out you experimenter
types out of all this.
Put a glass slurry in your small lab reactor and see what happens.
As for the fusion people and/or migma people, the NSTX, ITER etc. are
plenty big and energetic.
The D,D and D,T fusion reactions occur at 50 to 200 keV. People with 1
MeV Van de Graaff's
around can work on fundamental fusion studies instantly (see my radsafe
postings on warm
fusion). Also many physics departments have 200 keV accelerators around
that are usually
used for ion implantation. W. Michigan U. still has a 6-12 MeV van de
Or if you are all for library and/or web searches, you can look back
into when the original
fusion studies were done and what the results were. Some academic posters
(not radsafe lurkers!!!) may actually remember when such fusion studies
Guess I'd better dust off my copy of MCNP and get back to work.
Have a good week!!!! Joseph R. (Joe) Preisig, PhD
More information about the RadSafe