Modeling a Chain Reaction
In a nuclear fission chain reaction, a nucleus is struck by a neutron, which causes the nucleus to split into two smaller nuclei and to release other neutrons. If these neutrons strike other nuclei, a chain reaction can occur. In this lab, you will model a nuclear fission chain reaction using dominoes.
Problem How can you make a model of a nuclear fission chain reaction?
Materials
20 dominoes
watch with a second hand, or stopwatch
metric ruler
Skills Observing, Using Models
Procedure
Stand 15 dominoes in a single straight row in such a way that the distance between them is about one half of their height. Knock over the first domino. Measure and record the time it takes for all the dominoes to fall.
Repeat Step 1 two more times. Then, average the three time measurements to get a more accurate time.
Arrange 15 dominoes as shown below so that each domino will knock over two others. Observe what happens when you knock over the first domino. Measure and record how long it takes for the whole set of dominoes to fall over.
Repeat Step 3 two more times. Average the three time measurements to get a more accurate time.
Set up 15 dominoes again as you did in Step 3. This time, however, hold a metric ruler on end, in the middle of the arrangement of dominoes, as shown in the photograph on the next page. Knock over the first domino. Observe what happens.
Set up 15 dominoes as you did in Step 3, but this time, place 5 additional dominoes behind and at right angles to 5 randomly chosen dominoes for support, as shown below. The 5 supported dominoes represent atoms of a different isotope that must be struck with more energy to undergo fission.
Knock over the first domino. Measure and record the time it takes for the dominoes to fall and how many dominoes fall.
Repeat Steps 6 and 7 two more times. Then, average the three time measurements to get a more accurate time.
Repeat Steps 6 through 8, but this time, place supporting dominoes behind only 3 dominoes.
Repeat Steps 6 through 8, but this time, place a supporting domino behind only 1 domino.