How to Calculate a Radioactive Source Term

Radioactive waste has a source term that can be determined with four equations.

Radioactive materials, such as uranium, are measured in half-lives. The source term refers to the origination date of the material. There are also three other measurements that are determined by the source term. These are chemical forms, amounts and frequency of releases. This information is used by environmentalists when coming up with the best way to clean up a radioactive dumping site or contaminated ground. In order to have an accurate plan, they need to know exactly what they are dealing with. There are four equations that can help you find the source term, depending on what information you already have.

Instructions

1. Figure out the becquerels. A becquerel is a unit of radioactivity, and is the quantity of nucleotides that decay in one second. This equation is Q=KT*M*N/W. Q is the amount of becquerels. You will need to know the disintegration constant (KT), the nucleotide mass (M), Avogadro's number (6.02 times 10 to the 23rd power) (N, in the equation) and the radionuclide atomic weight (W).

2. Find the radionuclide atomic weight. The radionuclide is the unstable portion of the material that disintegrates. You will need to know the amount of becquerels (Q), the disintegration constant (KT), the nucleotide mass (M) and Avogadro's number (N). The equation is W=KT*M*N/Q.

3. Calculate the radionuclide mass. This is the weight of the unstable portion of the isotope. The equation for coming up with the measurement is M=Q*W/KT*N. To solve it, you need to know the amount of becquerels (Q), the radionuclide atomic weight (W), the disintegration constant (KT) and Avogadro's Number (N).

4. Solve the equation to determine the disintegration constant, which is a measurement of how much the isotope decays in a given amount of time. In order to come up with this number, you need to know the amount of becquerels (Q), the radionuclide atomic weight (W), the radionuclide mass (M) and Avagadro's Number (N). The equation is KT=Q*W/M*N.

References

• Centers for Disease Control: Source term estimates
• The Free Medical Dictionary: Becquerels
• Lawrence Berkeley National Laboratory: Glossary of nuclear terms
• Georgia State University Department of Physics and Astronomy: Radioactive half-life