[ RadSafe ] [RadSafe]Mission to Mars---Fission Propulsion
JPreisig at aol.com
JPreisig at aol.com
Fri Jan 2 23:17:43 CST 2009
This is from: jpreisig at aol.com .
Radsafers <Happy 2009>,
Thanks to Jerry Lahti for discussing NERVA and publication
NASA-TM X-2440. Maybe someday I'll get my hands on this document.
Project cancelled in 1972??? Too bad --- I know there are University
research projects still focussed on fission/fusion space propulsion at
Michigan, Princeton, etc. I'm sure NASA, etc. is still making progress
in this area, even if it is not being too vocal about it. Tactical flight
velocity advantages over the Soviets, etc. are still a consideration in
this. Perhaps Jane's Aeronautical publications out of Great Britain would
Yes, shielding of a spaceship space crew and reactor would be
necessary for space flight. And of course some shielding for solar
cosmic rays, etc. for the spacecraft would be necessary also.
The American Geophysical Union <not really a trade union, but rather
a scientific society like the HPS> has publications and AGU Meetings
which have sections dedicated to solar flares, ionosphere, etc. for
with interest in those things. Membership is something like 20 dollars
per year in the USA which includes subscriptions to Physics Today and
EOS, a weekly AGU newsletter. See their website. Other AGU publications
As for "gamma modelling from large sources", another topic on
Radsafe, sure take your best shot at making an analytical or numerical
calculation, first. Make measurements also. Then do yourself a big
buy a copy of MCNP from Oak Ridge or Los Alamos, and set up the
problem on MCNP. A good analyst can probably set up the basic geometry
in one day. With today's PC's one can probably set up an overnight MCNP
run which will give excellent statistics by the next morning. Then
the problem's detector positions as needed, and run MCNP again.
Compare ALL results --- modelling CAN BE DONE on such a problem
Neutron problems??? --- Use MCNP also. Use calibration equations
given in the papers by Eisenhauer and Schwartz <USA> and Hunt
<Great Britain>. If necessary, make measurements using Bonner Spheres
and activation detectors --- see Patterson and Thomas's book for
background on all this. Analyze the neutron data using BON4/BON5 or
whatever unfolding code for neutron data you have. BON4/BON5 is
available from Oak Ridge <RSICC --- Radiation Shielding Information
A PC version of BON4/BON5 might be available from H. Kahnhauser
<a manager> at Brookhaven Lab. I've discussed the problems with
BON4/BON5 and its data graphics in the Radsafe archives. When in
doubt with BON4/BON5, plot the flux density/fluence data by hand on
graph paper. You'll see nice neutron cascade, evaporation neutron peaks
and thermal neutron peaks in your BON results, just like the
big USA national laboratories get. Neutron data normalization should be
properly done with respect to an array of all <7 or whatever?> Bonner
detectors --- data normalization with respect to only one detector is
good enough. The factors "C or c" in the Bonner unfolding equation,
referred to in Patterson and Thomas's book are calibration factors and
can be found empirically or by another less empirical way. My goodness,
I'm not going to tell you all in one e-mail how to do all this to the
one percent Percent Average Error level in BON4/BON5. Kahnhauser has
my Bonner Multisphere Spectrometer procedure at Brookhaven. Who he
chooses to share such a document with is D.O.E.'s <USA> business.
Sorry, I've started to go off on all this a bit. LOUHI, BUNKI,
all probably pretty good neutron unfolding etc. codes.
Some USA business-man is financing his own spacecraft flight
Have a good week at work.
Regards, Joseph R. <Joe> Preisig, Ph.D.
P.S. To the guy in Paris, the lone geoscientist on Radsafe????, my MA and
Ph.D are in geophysics. I'm sure there are other geoscientists
on Radsafe also!!! Do not feel so alone!!!!
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