Nuclear power

Assignment: Create a page that illustrates the following aspect of nuclear power production. Use other sources as much as possible and acknowledge them properly. Note that these questions are rooted in topic 6 in the syllabus, but are developed in topic 8 which discusses energy production.

The Role of the Chain Reaction in Nuclear Power Production

(1)

In nuclear power production, a neutron is fired at an atom, causing fission and in the case of Uranium-235, the release of two more neutrons. This causes the process to repeat itself all over again; each neutron triggers another atom's nuclear fission and produces two neutrons for another two nucleuses. Therefore the rate of fission rises exponentially in nuclear reactors.

235U92 +  1n0    -->   fission products + (2.5)1n0   +  200 MeV Energy

This equation defines how U-235 reacts with neutrons and splits.

However, while nuclear fission produces several neutrons, not all of these neutrons can go on to cause fission elsewhere; only low-energy neutrons can cause fission. Low energy refers to about 1 eV. Therefore it follows that if useable neutrons are not produced faster than fission takes place, the chain reaction will eventually die out and end.

(3)

"The smallest mass of fossile material that will support a self-sustaining chain reaction under specified conditions" (2), or the smallest amount of material that won't die out and end, is known as the Critical Mass.

The figure for critical mass can change. Depending on the shape of the material, what the material is made of and how dense it is, and whether or not it is contained within a "neutron reflector," the amount of material necessary for a sustainable chain reaction can be changed. (1)

WERLIN :) AOKI :) and LEE :)

(1) Atomic Archive. accessed 15/09/08. "Nuclear Chain Reactions." URL: http://www.atomicarchive.com/Fission/Fission2.shtml

(2) World Nuclear Organization. accessed 15/09/08. URL: http://www.world-nuclear.org/info/inf51.html

(3) Settle, Frank. accessed 17/09/08. URL: http://www.chemcases.com/nuclear/nc-05.htm