Research Assignment: Modeling Radioactive Decay

Research a radioactive material used within your community (city, state, or country) whose decay can be modeled using a differential equation.
State the equation for your model and cite the reference.
Graph the equation for the model. The graph does not have to be to scale.
Make a prediction using the model.
Find the limit of your model. How long will it take for the material to become “safe”? “Safe” means that the radiation coming from the material is no longer a danger to public health.