When the operator of a nuclear facility (i.e. the licence holder) is to decommission the facility, this must be done in a way that protects people and the environment from radioactivity in the facility. The Swedish Radiation Safety Authority issues regulations governing the planning and undertaking of dismantling activities; what’s more, the Authority performs checks to ensure that the licence holder takes responsibility for the safe decommissioning of the facility.
The nuclear power industry is responsible for ensuring that its nuclear facilities are decommissioned in a safe way. The industry is also responsible for the management and disposal of its radioactive waste. Both the processes of preparation and the actual dismantling of facilities can take many years.
The objective of decommissioning is to remove radioactive material from the site in question so that the area can be used for other purposes. Decommissioning starts when the original operation is permanently terminated. In the case of a reactor, this for instance involves removal of all fuel from the reactor core.
Keeping radiation protection in mind
When a nuclear power reactor is going to be shut down for decommissioning, the Swedish Radiation Safety Authority intensifies its regulatory supervision since there is a risk that the safety culture might deteriorate in connection with the shutdown. For this reason, we visit the facility more frequently until the reactor in question has been shut down. We closely monitor the impact that the decision to shut down the reactor has on the organisation to ensure that all employees continue to maintain awareness of safety and radiation protection and so that a sufficient number of competent personnel remain in the organisation.
When the reactor has been shut down, the risk of serious accidents is reduced considerably, particularly once the spent nuclear fuel has been removed from the facility. At that point in time, our work focuses on checking to ensure that those responsible for the facility prepare the dismantling work in such a way that it can be carried out as safely as possible. This includes planning to ensure that the personnel’s radiation doses are as low as reasonably achievable and so that the risk of discharges of radioactive material and accidents is also as low as possible. They must also plan for how the waste from dismantling will be sorted, treated and stored, alternatively recycled.
Dismantling step by step
During decommissioning, the licence holder operating the nuclear power plant is required to remove all radioactive material and restore the site so that it can be used for other purposes. In an initial phase, all the spent fuel is transported to Clab, the central interim storage facility for spent nuclear fuel located in Oskarshamn. Remaining personnel work on preparations at the facility for its future dismantling. Besides keeping the facility in a safe state, the personnel determine the presence of radioactive substances at the facility, remove radioactive contamination if possible and manage new and remaining radioactive waste. It is common to clean the reactor system using chemicals in order to remove most of the radioactive contamination from surfaces. After this stage, the facility can be dismantled in different ways, for example depending on whether or not it is possible to treat and store waste at the facility site.
During decommissioning, the reactor system is dismantled together with other system components and pieces of equipment that have become radioactively contaminated, in some cases using special tools that are remotely controlled. Virtually all installed systems are removed to make it possible to perform careful checks to ensure that no radioactivity in the buildings has been overlooked. Ultimately, the buildings that are not going to be used for any other purposes are demolished.
Decommissioning gives rise to large quantities of low level and intermediate level radioactive waste. The intention is for this waste to be disposed of underground at SFR in Forsmark, in local shallow land disposal facilities for nuclear waste or stored in some other way until a repository has been constructed. However, it is possible to recycle or manage as much as 98 per cent of waste from dismantling as ordinary construction waste because it has never been exposed to any radioactive contamination. On the other hand, materials that might be radioactively contaminated must be carefully surveyed to ensure that the materials are safe and to prevent radioactive waste from being misplaced. Special authorisations are required under the Act on Nuclear Activities and Environmental Code in order to dismantle and demolish the facility.
Once radioactive materials have been removed and the radioactivity has been reduced to the levels prescribed, the decommissioning is viewed as completed under the Act on Nuclear Activities and Radiation Protection Act.