Project Title:

Nuclear Decay

Brief Description of Project:
This project is to be used after the rabbit model. It will create a model of nuclear decay.  This simple model could be the basis of a full project.

Grade Level:
9-12

Desired Number of Participants (if collaboration with other classes):
Class

Project Timeline:
1 hr

Curriculum Subject Area(s):
Physics, Physical Science, Earth Science

Objectives of Project:
The student will:

Materials/Resources: (List Both on-line and off-line materials/resources needed)

On-line:

Off-Line:
STELLA

Procedure(Step by step instructions for developing the project):

After the teacher has demonstrated exponential growth with a STELLA model, the students should be given these instructions.

Computer Simulation of Nuclear Decay

Seemingly unrelated phenomena, like the growth of a rabbit population and the decay of a radioactive sample, can in fact be quite closely related mathematically. A model for the growth of a rabbit population exhibited an exponential growth curve.

The decay of a radioactive sample exhibits exponential decay. Try modifying the rabbit population growth equation

N = Ninitial x emt

to produce exponential decay (this will involve the introduction of a negative sign at some point in the equation). Experiment with the rabbit model to find where the negative sign should be introduced. Then change the initial population to 1000, change the label of the initial population from "initial rabbits" to "initial atoms," change the title of Column B from "rabbits" to "atoms," change the y axis label of the graph to "atoms," change the x axis label to "time (days)," and change the title of the graph to "Nuclear Decay."

Now, try the following experiments, and fill in the worksheet:

1. Given the following multipliers for several radioactive isotopes, use your model to determine how long it will take for each isotope to decay to half the original population of atoms (this elapsed time is called the halflife of the isotope).
 
Isotope Multiplier Halflife
P-32 0.04854/day
S-35 0.00789/day
Ca-45 0.00420/day
Fe-59 0.0152/day
Zn-65 0.00283/day
 

2. One of the major products of the fission of U-235 is I-131, which has a halflife of about 8 days. Determine, by experimenting with your model, what the value of the multiplier would have to be in this case:______________.
 
 
Extensions to other subject areas:
Hazardous Waste storage
 
Student Evaluation Method:
Worksheet answers
 
Project Evaluation