Quantity of radionuclides (number of nuclear decays per time interval).

Caesium-137 (also Cs-137) has a half-life of approximately 30 years, which means that after a period of 30 years, the amount of Cs-137 will have halved due to radioactive decay. Due to its long half-life, caesium-137 is the most important nuclide in respect of long-term contamination and, without countering actions, the most significant nuclide for…

Containment comprises the primary and secondary containment. Primary containment is the containment building that surrounds the nuclear part of a nuclear power plant. Containment forms a part of the safety barriers which, in the event of an accident, prevent the uncontrolled release of radioactive substances into the environment. For more information, see the sixth part of…

The radioactive decay of fission products generates heat which, if there is no cooling, results in impermissible overheating of the fuel. Then a core meltdown occurs when the fuel heats up until its melting point is reached.

Decontamination refers to any work that contributes to the removal of contamination. The deposited radioactivity is thus reduced, for example by the removal of a soil layer or by the high-pressure rinsing of a surface. This produces radioactive waste which must be captured and correctly disposed of.