Radiation Safety Practice Exam

What is a major risk associated with thorium alloys?

1. High internal exposure risk

2. Environmental pollution

3. Low risk of internal exposure

4. High risk of chemical reaction

The correct answer is: Low risk of internal exposure

The choice indicating a low risk of internal exposure aligns with the understanding that thorium, while radioactive, has certain characteristics that contribute to a reduced risk of internal exposure, particularly when compared to other radioactive materials. Thorium's primary isotope, thorium-232, has a long half-life of about 14 billion years, meaning it decays very slowly and emits low levels of radiation. In many applications, such as in foundry metal additives or certain types of nuclear reactors, thorium is more stable than other uranium-based systems, which can lead to fewer occupational exposure scenarios. Additionally, the compounds of thorium that might be of concern tend to have lower solubility in biological systems, which reduces the likelihood of absorption in the body and subsequent internal exposure. It's important to note that while thorium has a lower risk of internal exposure relative to some other radioactive elements, this does not eliminate all risks associated with its use, such as environmental pollution or other chemical hazards. However, in contexts where thorium alloys are managed properly, the risk of internal exposure can indeed be considered low.