Re: How are neutrons accelerated in nuclear Fission reactors?

Edward,

Neutrons are not accelerated in nuclear fission reactors.

The fission reaction is started with a neutron source inside the reactor 
vessel
which may emit neutrons through an alpha,neutron reaction, for example.

Starting out, control rods are inserted in amongst the fuel rods to "kill"
neutrons that may be interacting with the fuel.  The control rods are made 
of
materials that are generally referred to as neutron "poisons" and other
materials that moderate (or slow down) neutrons.  With the control rods 
fully
inserted in the core, the nuclear chain reaction is referred to as "sub
critical" or non-self-sustaining at this point.

As the control rods are slowly removed from the core, more neutrons are 
freed
up to create more and more chain reactions which eventually become
self-sustaining.  The of the nuclear chain reaction is to have it become
"critical" or have a neutron multiplication factor at or slightly above 1 - 
-or for every one neutron that creates a fission, only one neutron of the 
three
emitted during the fission is allowed to go on and create a secondary 
fission
and so on.

Neutron multiplication factors well above 1 (2, 3, 4, etc.) are highly
undesirable and generally result in a runaway or "supercritical" reaction.

So the "acceleration" of neutrons during the fission process is only due to 
the
kinetic energy imparted by the break up of the atom, not due to any external
acceleration process.

A web search on "nuclear fission" will yield may links that will provide
additional information on this subject.

v/r
Michael