The description of what leaves the plant in an accident: which radionuclides, how much activity, in what chemical and physical form, and when. Iodine, caesium and noble gases usually dominate the consequences. Design basis source terms are prescribed and conservative for licensing dose calculations, while severe accident source terms come from best-estimate analyses and feed emergency planning and off-site dose projections.
Dose assessment is using the default source term until we get a containment sample back.
Related terms
Severe accident
An accident involving significant damage to the reactor core, with possible fuel melting and large releases.
Plume
The cloud of radioactive gases and particles carried downwind from a release.
Containment
The massive, leak-tight structure around a reactor that holds in radioactive material and steam if the coolant system fails.
EPZ
Emergency planning zone: the area around a nuclear plant where protective actions are pre-planned.