This program is basically intended to model the nuclear chain
reaction in a very simplified way. Different arrangements can be collected from some
beforehand defined triangular shaped components, like uranium rods with different
enrichment (natural, 5% and 100%), different moderators (light water, heavy water,
graphite), control rods and neutron sources. Then it can be checked whether a controlled
nuclear chain reaction has developed or how it can be made controlled. The enrichment of
the uranium and the moderator can be defined in the Options menu.
How the program works:
The neutrons in the separate cells can be
divided into two groups: fast neutrons and thermal neutrons. The quantity of these
neutrons is indicated by numbers of different colour. On each time signal the following
things can happen (with different probabilities) to the neutrons in the cells:
- neutron generation (as fast neutron in uranium rods or neutron
sources)
- neutron absorption (except for the empty cells)
- fission (only in the uranium rods)
- neutron moderation (only the fast neutrons)
- neutron passing to an adjacent cell
The "multiplication factor" is
calculated by the computer in the following way: the program divides the number of
neutrons in the cells, which are not empty, by the number of previous generation neutrons
in the same cells. (Since the number of neutrons varies statistically, therefore the
calculated multiplication factor also varies.)
Task:
Create an arrangement which exactly critical by using natural
uranium and as low number of components as possible. How many uranium rods did you have to
use?
Check how many uranium rods with at least 5% enrichment is required
for a critical system when using water, heavy water or graphite as a moderator.
Why it is reasonable to switch off the temperature feedback when you look
for critical mass?
Some advices: To start a self-supporting nuclear chain reaction a neutron
source is always required. Therefore when making the arrangements include a neutron source
and keep it in operation over a few generations, then replace it with an other component.
The program makes it possible to modify an arrangement "in operation" (Push
the Pause button, then modify the arrangement and then you can continue the simulation).
Some parts of the diagrams can be highlighted and zoomed by pushing the Shift button and
clicking on them by the mouse. By pushing the Shift button and clicking by mouse on the
diagram the original size can be reset.
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