Course of events leading, for safety reasons, to a discontinuation of the facility’s operation or the activity. The facility must be designed for this course of events or precautions must be taken for the activities.

Temporally limited storage of spent fuel elements or radioactive waste prior to their disposal. Spent fuel elements are to be stored in decentralised interim storage facilities on the sites of the nuclear power plants, in fact until they have been conditioned suitably for disposal in a repository.

Facilities where spent fuel elements can be stored in appropriate transport and storage containers on the site of a nuclear power plant until their conditioning suitable for disposal in a repository. Storage time is planned to be 40 years at maximum, starting at loading of the first container.

Radioactive waste requiring additional shielding of the containers when being handled.

Atoms of one and the same chemical elements with the same number of protons (same atomic number but different nuclear number) and electrons but different number of neutrons. Isotopes have the same chemical but different nucleonic characteristics.