Procedure

Decommissioning and disposal

Responsibility and duties

The owners of Swiss nuclear facilities are legally obliged to dismantle their facilities after decommissioning and to dispose of all radioactive waste safely. They bear all costs associated with decommissioning and disposal.

Decommissioning includes all activities up to the point at which the nuclear facilities are no longer bound by the Nuclear Energy Act (NEA). The obligation to dispose of waste ceases once the waste has been emplaced in the deep geological repository and the financial resources for the subsequent monitoring phase and any sealing of the repository has been secured.

Decommissioning project and preparation for dismantling

For the definitive decommissioning of a nuclear facility, the owners draw up a decommissioning project while the facility is still in operation and submit it to the Swiss Federal Office of Energy (SFOE). Once the documents have been successfully reviewed by the Federal Nuclear Safety Inspectorate (ENSI), the responsible Department of the Environment, Transport, Energy and Communications (DETEC) issues the decommissioning order.

If a nuclear power plant is shut down and no longer generates electricity, its operational status is deemed to have been permanently terminated. Following this, the post-operational phase is established and the plant is prepared for decommissioning. Once this has been completed and the legally binding decommissioning order has been issued, the plant can be taken out of service for good.

Nuclear and conventional dismantling

Nuclear dismantling is carried out from the inside out. The first step is to remove the fuel assemblies from the plant. As the deep geological repository is not yet in operation, they are safely stored in the central interim storage facility (Zwilag) in Würenlingen (AG) or at the Beznau interim storage facility (Zwibez).

In parallel with the removal of the fuel assemblies, the first systems and plant components at the nuclear power plant that are no longer required are taken our of service, dismantled and removed. During dismantling, the non-radioactive components are separated out and recycled or disposed of like conventional waste.

Components on which radioactive substances have been deposited are decontaminated before they are also recycled or disposed of. In the end, only a few percent of all dismantling material is stored as low- or intermediate-level waste.

Around six to eight years after the fuel assemblies have been removed, the plant which is in the process of being dismantled is free of radioactive material. Once this has been confirmed by ENSI, the site of the former nuclear power plant is regarded as a normal industrial site. Conventional dismantling begins once approval has been granted. The entire decommissioning process, from the final termination of the operational status, preparatory work, nuclear and conventional dismantling through to conversion or near-natural reuse, takes between twelve and fifteen years, according to our present knowledge.

Disposal

Radioactive waste is disposed of independently of the operational, post-operational and dismantling phases of a nuclear power plant. Spent, high-level radioactive fuel assemblies and low- and intermediate-level radioactive waste are temporarily stored at Zwilag and Zwibez. Once the deep geological repository has been commissioned, the waste is gradually transferred to the underground storage chambers. According to the Nuclear Energy Act (NEA), it must be possible to retrieve the stored materials without undue effort during the monitoring phase. The deep geological repository will then be permanently sealed.