Pursuant to Articles 26 and 31 of the Swiss Nuclear Energy Act (NEA), the owners of nuclear installations in Switzerland are responsible, at their own cost, for the final shutdown of their installations and for disposing of any radioactive waste originating from the installations. To safeguard the financing of decommissioning and disposal, the owners are obliged to make contributions to the decommissioning and disposal funds (Art. 77 NEA).
The estimated costs of decommissioning and disposal are regularly reviewed. According to Art. 4 of the Decommissioning and Disposal Fund Ordinance, (DDFO), the owners of the nuclear power plants and the Central Interim Radioactive Waste Storage Facility at Würenlingen (ZZL) who are liable to pay contributions, are obliged to prepare a study every five years on the estimated disposal costs (cost study).
The 2021 cost study was submitted to the Administrative Commission of the Nuclear Installation Decommissioning and Nuclear Power Plant Disposal Fund (STENFO) in October 2021 and forms the basis for the assessment of provisions and fund contributions for the years 2022 to 2026.
With the support of external experts, ENSI has examined the information contained in the 2021 cost study in respect of the safety-relevant aspects (Art. 4 para. 4 DDFO). ENSI’s review focussed on issues that may be relevant in determining the costs and its statement concerning the 2021 cost study was submitted to the STENFO Administrative Commission in May 2022 as planned.
ENSI came to the conclusion that the technical, scheduling, organisational and operational assumptions for the cost calculation comply with applicable regulations and standards, and reflect the state of the art. The technical data basis for determining the decommissioning and disposal costs in the 2021 cost study is complete and of suitable quality. The information is also consistent with other documents and projects and is, therefore, a suitable basis for further considerations to be made by the STENFO Administrative Commission. In its statement, ENSI also formulated 13 recommendations on decommissioning and 9 recommendations on disposal. The individual findings of the ENSI safety assessment on the “Decommissioning” and the “Disposal” sections are summarised in Chapter 6 of ENSI’s statement.
Essentially, ENSI notes that the provisions of the STENFO Administrative Commission for the 2021 cost study relating to the basic technical information have been implemented in respect of content, albeit with two exceptions: Provision 8 regarding recommendations for reviewing the 2016 Cost Study and Provision 12 regarding decommissioning planning have not been fully implemented.
ENSI’s recommendations from the Statement on the 2016 Cost Study concerning the “Disposal” part have been considered in full, those relating to the “Decommissioning” part have, however, only partially been taken into consideration. The experience from the ongoing decommissioning of the Mühleberg Nuclear Power Plant and the decommissioning planning for the Beznau Nuclear Power Plant have only partly, or have not, been immediately considered. These findings have been incorporated into ENSI’s recommendations for the next cost study.
Following prior legal proceedings, STENFO was able to finalise the 2016 and 2021 cost studies, and the decisions taken by STENFO in this regard became legally binding at the start of 2026. Subsequently, ENSI published its statement on the 2021 cost study.
