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Re: Why Hafnium?



At 8:05 AM on 4/29/97, <phys-l@mailer.uwf.edu> wrote:


A student of mine that went through a nuclear training program while
in the Navy mentioned that Naval reactors use Hafnium as control rods
instead of Cadmium. It was interesting to then find that several
consecutive stable isotopes of Hafnium have a fairly high cross section
for neutron capture. However, elemental Cadmium has a cross section
of 2,450 barns while elemental Hafnium has a cross section of only
about 100 barns.

Question: Why is Hafnium used instead of Cadmium?

Could it be that the use of Cadmium for such a size of reactor would
make the control TOO sensitive??

Tom Walkiewicz walkiewicz@edinboro.edu
Department of Physics http://www.edinboro.edu/~Walkiewicz/home.html
Edinboro University office: (814)732-2468
Edinboro, PA 16444

The apocryphal story is that ADM Rickover was presented with two control
rods, one of cadmium and one of hafnium. He slammed them on the desk, and
the cadmium rod broke.

J. D. Sample (501) 698-4625
Math-Physics Dept sample@lyon.edu
Lyon College
2300 Highland Road
Batesville, Arkansas 72501