Navy Rx neutrons

["George R. Cicotte" <gcicotte@cbvcp.com>]

The U.S. Navy nuclear propulsion program differs in neutron exposure
primarily in that they perform essentially no at-power reactor compartment
entries, whereas commercial nuclear power does so periodically, for a
variety of reasons.  Navy reactors use shielding which captures enough of
the neutron flux, and the reactors are designed to reflect neutrons inward
for reactivity purposes, such that dose rates are very low.  I recall an
article in Scientific American, which was cleared by the Navy for
publication, in about December 1975 or January 1976, which described these
aspects of Navy reactor design in what I thought at the time was shocking
detail.  They even had a cutaway view of the internals of an S5W reactor.

At any rate, I've performed neutron surveys on the shield walls of Navy
reactors while at 100% power, with a tissue-equivalent BF3 detector, and the
dose rate was such that if you lived there for 24 hours a day, you still
would just barely receive an occupational exposure to neutrons.  Add the
gamma and it's a little different story, but you weren't supposed to sleep
there anyway.

Sincerely,

George R. Cicotte
gcicotte@cbvcp.com

DISCLAIMER:  No one to blame but myself