E.4.4—Fission products and waste
- Syllabus
- First assessment 2025
- Objective
- —
- Level
- SL
Manage Fission Products
Identify the products and the hazard
Fission produces two medium-mass fragments, free neutrons, radiation and energy. Many fragments are neutron-rich and radioactive; their decay produces ionizing radiation and continues to release thermal energy after the chain reaction stops.
| Property of waste | Consequence | Management response |
|---|---|---|
| High initial activity and decay heat | Strong radiation and continued heating | Shield and cool spent material, often first in water ponds |
| Mixture of half-lives | Hazard changes over different timescales | Monitor, classify and contain waste according to activity and lifetime |
| Long-lived radionuclides | Isolation is needed beyond normal operational times | Use durable containers and secure long-term storage, such as a suitable geological repository |
Judge the management problem
A long half-life does not automatically mean a greater activity: for the same number of nuclei, a longer half-life means a smaller decay constant. Waste decisions must consider amount, radiation type, activity, heat, containment and timescale together.
Common trap
Do not assume shutting down the chain reaction makes spent fuel immediately safe. Unstable fission products continue to decay after neutron-induced fission has stopped.
Retrieve the Fission Model
Retrieve the chain
Fission converts nuclear binding and mass defect into energy. A controlled chain reaction depends on neutron energy and losses; moderator, control rods, heat exchanger and shielding perform different jobs.
Retrieve the safety boundary
Fission products can be radioactive and require containment, shielding and long-term waste management.