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From power operation to decommissioning

The final shutdown of a nuclear power plant is followed by the post-operational phase in the course of which measures can be carried out to prepare decommissioning.

Timetable decommissioning Timetable decommissioningTimetable for the transition between power operation, post-operational phase and decommissiong of a nuclear power plant until it is released from nuclear regualtory control

Measures in the post-operational phase

The measures in the post-operational phase are covered by the operating licence held by the nuclear power plant owner. Generally, the following measures are carried out in the post-operational phase:

  • Unloading of fuel elements from the reactor,
  • Reloading of the fuel elements into storage containers and storage in the on-site interim storage facilities,
  • Utilisation of radioactive materials and removal of radioactive waste having accrued in the operational phase,
  • Decontamination of facility and systems,
  • Taking samples from systems and components required for application for decommissioning.

It is the operators decision to apply to the competent nuclear licensing and supervisory authority for further adjustments in the post-operational phase, taking into account the relevant risk potential.

Safety in the post-operational phase

During the post-operational phase the necessary precaution against damages needs to be taken according to the state of the art of science and technology. As in the operational-phase the radioactive material must be enclosed and the radiation exposure must be limited.

As long as fuel elements are in the nuclear power plant precautions have to be continued to cool the fuel elements and to control the reactivity. The control of reactivity must ensure,

  • that during operation exactly one fission neutron causes a new fission (criticality) and
  • that after shut down the reactor will not become critical.

The precautions in the post-operational phase are covered by the operational licence still in force.

After the post-operational phase

The decommissioning of a nuclear power plant following the post-operational phase requires a comprehensive licensing procedure comprising in particular radiation protection aspects and possible impacts to the environment. Only after a decommissioning licence has been granted can those works start that change the systems and components essentially and will finally lead to the dismantling of the nuclear power plant.

State of 2016.08.29

© Federal Office for the Safety of Nuclear Waste Management