Message-ID: <AZggASO00VcJIDZE4v@andrew.cmu.edu>
Reply-To: space+@Andrew.CMU.EDU
From: space-request+@Andrew.CMU.EDU
To: space+@Andrew.CMU.EDU
Date: Tue, 16 Jan 90 01:45:50 -0500 (EST)
Subject: SPACE Digest V10 #432

SPACE Digest                                     Volume 10 : Issue 432

Today's Topics:
		Re: reactors in space, active control
----------------------------------------------------------------------

Date: 16 Jan 90 01:55:39 GMT
From: rochester!dietz@pt.cs.cmu.edu  (Paul Dietz)
Subject: Re: reactors in space, active control

In article <4481@scolex.sco.COM> natei@sco.COM (Nathaniel Ingersoll) writes:

>I may not understand the above right, but -
>water stops, or at least slows, neutrons in order to capture
>some of their energy, turning it into heat.  Neutrons that are
>slowed do not take further part in the nuclear reaction;

No -- slow neutrons are *more* effective than fast.  In general,
the cross section of nonresonant neutron reactions at moderately
low energy is inversely proportional to the velocity of the
neutron.

The TRIGA research reactors achieve passive safety by making the
fuel rods out of uranium hydride.  As a result, the hydrogen
there (and therefore the neutrons) heats up instantly if the
reaction accelerates.  You can yank the control rods completely
out of a TRIGA; the power goes up for an instant to some very
large value before settling down.

	Paul F. Dietz
	dietz@cs.rochester.edu

------------------------------

End of SPACE Digest V10 #432
*******************