Review of the study 2011 on the cost of decommissioning and radioactive waste disposal of the nuclear facilities in Switzerland

Owners of nuclear plants are obliged to estimate the costs for decommissioning their plants and for disposing of the waste and to ensure the relevant financing. For this reason, the owners pay an annual contribution into the decommissioning fund and the disposal fund. The level of contributions to these funds is stipulated on the basis of cost studies and the status of the funds, which must be updated every five years. The cost studies are carried out by 'swissnuclear', the members of which are the four operating companies of Switzerland's nuclear power plants and the Zwischenlager Wuerenlingen AG (ZWILAG/ZZL, Interim Storage Facility Wuerenlingen). The new cost studies indicate that the post-operational phase and decommissioning of Switzerland's nuclear plants, and the disposal of radioactive waste, will cost a total of CHF 20.7 billion. Some of the disposal costs will be incurred during operation and paid by the operators on an ongoing basis: research and preparatory work, reprocessing of spent fuel assemblies, setting up the ZZL and procuring transport and storage containers. This portion amounts to about CHF 7.5 billion up to the point when the five nuclear power plants will be taken out of service. By the end of 2010, the operators had paid about CHF 4.8 billion of this sum. ENSI is mandated to carry out technical reviews of the studies on decommissioning and disposal costs, and to draw up a statement for the Administrative Boards of the Decommissioning Fund and the Disposal Fund. ENSI has called on external experts in order to review the cost studies for the decommissioning of the nuclear plants and for the construction of the underground facilities for the deep geological repositories. The cost estimates 2011 (CS11) are 'best estimates': costs are expenses based on a detailed technical and scientific concept, in accordance with the latest knowledge available. The planned individual work packages fully cover the dismantling of the nuclear plants. ENSI and its experts conclude that the nuclear plants can be dismantled in the planned periods. The best estimate approach assumes that the work can be carried out without delays. The total costs of decommissioning the nuclear plants in Switzerland can be kept, provided that planning is optimised and that lessons already learned are incorporated. The costs of dismantling should reduce in the future because there is a constantly growing experience in dismantling nuclear plants throughout the world. The actual decommissioning costs will be within the usual industrial cost range of -15% to +30% as compared to the cost studies. This level of accuracy is adequate for the current status of planning. ENSI concludes that the documented total costs for the construction of the underground facilities for the deep repositories for low- and intermediate-level waste (L+ILW) as well as for high-level waste (HLW) are clear, complete and plausible in respect of construction procedures, time requirements, materials and maintenance. The costs were determined by Nagra on a thorough basis and with a relatively high level of detail. ENSI assesses the systematic procedure that was selected as adequate and fit for purpose. In practice, cost accuracy rates of ±25-30 % are agreed in the preliminary study phase of projects for underground construction work. The cost estimates include the resources required for positions that cannot yet be determined. The experts and the Nagra studies correspond well, the divergence being of -0.9% for the L+ILW project and +2% for the HLW project. ENSI assesses the CS11 cost estimate for the construction and operation of the L+ILW and HLW deep repositories as complete and plausible. ENSI makes the following recommendations for the next cost estimates: - A large amount of the radioactive waste in the ZZL originates from the disposal of Lucens waste (262 Mg). The costs of repacking and conditioning this waste should be taken into account or reported separately in the next cost study. - The decommissioning objective for the ZZL should also assume complete dismantling of the ZZL. - Conventional contaminants such as asbestos and PCBs can severely impede the dismantling work. They should be taken into account as additional costs.- Building structures below a depth of two meters should remain in the ground. ENSI advises the operators of nuclear plants to clarify the possible impact on groundwater protection. - Potential unforeseen delays should also be taken into account in the calculations of expenditure. - Experience from dismantling projects abroad, and from the computing programmes used in such projects, should be incorporated into the revision of the studies. - The estimates of the type and quantity of decommissioning waste from the nuclear plants by the University of Basel, the PSI, the Swiss Federal Institute of Technology, Lausanne, and CERN should be taken into account or updated. - The cost estimate for the sealing structures of the repositories should be compared with similar deep repository projects in argillaceous rock formations.