Which term is the number assigned to a package, overpack, or freight container to provide control over fissile material?

• A. Criticality Safety Index
• B. Transport Index
• C. Contamination
• D. Activity

Answer: (A)

The key idea is subcriticality control during transport of fissile material. The number assigned to each package, overpack, or freight container containing fissile material is the Criticality Safety Index. This index quantifies how much fissile material is present and is used to ensure that, when all such packages are loaded together, the total remains within limits that keep the system subcritical. That’s why this index guides how many packages can be shipped together and how they’re arranged.

The other terms refer to different safety aspects. The Transport Index measures external radiation level from the package and is used for radiation safety labeling, not subcriticality. Contamination describes radioactive material on surfaces or within environments, not a control parameter for fissile transport. Activity denotes the quantity of radioactive material, a measure of its decay rate, but not the specific subcriticality control used for fissile shipments.