Delayed radiation is caused by decay of which substances?

Delayed radiation is caused by decay of which substances?

• A. Fission fragments
• B. The initial fuel pellet
• C. Reactor coolant
• D. Shielding material

Answer: (A)

When a nucleus fissions, a wide array of fission fragments is produced, and many of these fragments are unstable. They decay over time toward more stable nuclei, emitting radiation in the process. This decay happens after the fission event itself, so the radiation is observed as delayed rather than immediate. The fission fragments dominate the residual, long-lasting radiation within the reactor and its surroundings. While materials like coolant or shielding can become radioactive through activation and contribute to residual radiation, the primary source of delayed radiation is the decay of the fission fragments.

When a nucleus fissions, a wide array of fission fragments is produced, and many of these fragments are unstable. They decay over time toward more stable nuclei, emitting radiation in the process. This decay happens after the fission event itself, so the radiation is observed as delayed rather than immediate. The fission fragments dominate the residual, long-lasting radiation within the reactor and its surroundings. While materials like coolant or shielding can become radioactive through activation and contribute to residual radiation, the primary source of delayed radiation is the decay of the fission fragments.