From: "Marcus H. Mendenhall" <firstname.lastname@example.org>
Subject: Re: Wax
Date: 05 May 1996
Along with the other good responses to the question about parrafin as
radiation shielding, I will add this. As was pointed out, it is
commonly used to slow neutrons to thermal velocities, but is very poor
at actually absorbing them. Actually, now, more often people use any
simply hydrogen-rich plastic, such as polyethylene or polypropylene,
since they have the same basic chemical makeup as paraffin (CH2 building
block, lots of hydrogen), but don't tend to melt on a warm day.
For best neutron shielding, though, these materials are often loaded
with borax, since boron is a very good absorber of thermal neutrons. It
is the combination of hydrogen as a moderator and boron as an absorber
which provides extremely good neutron shielding.