Semester of Graduation

Summer 2019


Master of Science (MS)


Physics and Astronomy

Document Type



Radioactive isotopes of iodine are produced by nuclear power plants as a byproduct of nuclear fission reactions. If these isotopes are released into the environment, such as during a breach of containment, they constitute a health risk to exposed individuals. To mitigate the risk of thyroid cancer due to exposure to radioactive iodine, “iodide prophylaxis,” also known as “thyroid blockade,” can be used, usually by administration of potassium iodide (KI). In some areas of the world, KI has been provided to the general public by their governments as a precautionary measure against potential nuclear power plant incidents. However, in the state of Louisiana, only evacuation and sheltering of the general public are the planned response to such incidents. The question of whether Louisiana’s government should provide KI to the public is a question of risk management. This project’s risk assessment provides a framework for determining radiation risk from radioiodine release from a nuclear power plant, enabling an assessment of the potential benefit of providing KI to the general public in Louisiana. In this assessment, a hypothetical radiological incident of similar severity to the Fukushima accident was modeled for a nuclear power plant in Louisiana. Environmental transport of discharged radioactive iodine was modeled with a Gaussian plume model. Thyroid dose was calculated using representative parameters from International Commission on Radiological Protection Publication 71. Age- and sex-specific values of excess relative risk, lifetime attributable risk, and excess lifetime thyroid cancers were calculated. Lastly, the number of excess lifetime thyroid cancers mitigated by thyroid blockade was estimated through two separate approaches. This assessment found that a plume traveling over highly populated parishes near the power plant could result in approximately 200 excess lifetime thyroid cancers over all age groups. The largest number would likely occur in females exposed as children. Thyroid blockade could potentially mitigate 80 or more of the excess cancers. These results suggest that more comprehensive assessments of KI distribution in Louisiana may be warranted.

Committee Chair

Wang, Wei-Hsung