Radiation in Lunar Regolith

--- In ssi_list@... "Arthur P. Smith"
>
>> Also note that radon is a gas, and a heavy one, which is why it's
a
> ground-level problem for homes etc. But if the regolith in
question was
> on the OUTSIDE of a spinning habitat, (1) it would blow away into
space,
> since "down" is actually "out" and a vacuum, and (2) given that
the
> habitat has to be air-tight anyway, very little of it should get
in
> through the seals. You might want to make sure the very outer
layer of
> the habitat is porous to radon to be sure it would get out. But I
think
> it would be safe to assume radon will not be a significant source
of
> radiation in most space habitats.
>
> Arthur

Good, we won't have to worry about radon exposure. Does that mean we
can increase the cosmic ray exposure? Do the two types of radiation
have the same effect on the body or do cosmic rays cause more damage
because of the secondaries and the nature of the cosmic rays
themselves?

Do we want to hold cosmic rays levels down to 52 millirems (Denver
levels) with the result that the Habitat would be a lower radiation
environment than living on the Earth!

Or would a level of 100 millirems of cosmic rays be acceptable
considering the Habitat would have no radon exposure? This would
reduce the shielding requirements.

Nevertheless, you'll note that the density of lunar regolith is
1.5g/cc.
http://www-curator.jsc.nasa.gov/curator/lunar/letss/Regolith.pdf

So where does the 2 meters of shielding requierment so often quoted,
originate from?

TangoMan