Increased storage of spent nuclear fuel at Clab in Sweden
Abstract
The purpose of this report is for Sweden to provide the European Commission with general information on increasing storage from a maximum of 8,000 tonnes to a maximum of 11,000 tonnes of spent nuclear fuel from Swedish nuclear power plants in the central interim storage facility for spent nuclear fuel (Clab) on the Simpevarp Peninsula in Oskarshamn. The report follows the guideline set out in Annex I on the recommendation for applying Article 37 of the Euratom Treaty (2010/635/Euratom). The report shows that an increase of the interim storage will not risk leading to radioactive contamination of water, soil or airspace in another EU Member State.
The licensee for Clab is Svensk Kärnbränslehantering AB (SKB). Commissioned in 1986, the facility consists of a receiving section at ground level and a storage section. The storage section consists of two rock caverns located more than 30 metres below ground, connected by a water-filled transport channel. Each rock cavern contains storage pools where the spent nuclear fuel is interim-stored with approximately eight metres of water cover. The increase in storage entails a gradual increase in the activity inventory and decay heat. The space, cooling of decay heat and maintenance of adequate radiation safety are accommodated within the framework of the current Clab facility. This will enable a gradual increase from 8,000 tonnes to 11,000 tonnes of spent nuclear fuel to be carried out in the existing facility with retained activities. The current limit of 8,000 tonnes will be reached at the beginning of 2024, after which a licence for increased storage will need to be obtained.
The information presented on radioactive discharges to air and water, during normal operation or events during interim storage of spent nuclear fuel, shows that there will be no discharges that would result in measurable dose levels in other Member States. According to the guideline in Annex I, no reporting of effective dose is required in other Member States provided that reporting is provided of doses to the reference group in the vicinity of the installation. This applies if the assessed maximum exposure levels from discharge under normal conditions for adults and children in the vicinity of the installation are below 0.01 mSv per year or below 1 mSv in the event of unplanned discharge and there are no other exposure pathways, such as, food exports. Doses close to the facility due to discharges to air and water is well below 0.01 mSv per year under normal conditions and well below 1 mSv in the event of an unplanned discharge. Therefore, it is not relevant to report calculations of doses to persons outside Sweden’s borders. The data, assessment methods and assumptions used in the calculations have been chosen conservatively to ensure that the results do not underestimate discharges and doses.
This report is based on investigations that form the basis for completed and ongoing licensing in Sweden. The conclusion from the studies is that discharges under normal conditions and possible events are only marginally affected by interim storage of 11,000 tonnes in relation to the current situation with interim storage of 8,000 tonnes. This means that both existing discharges of radioactivity and those from increasing the interim storage are well below the specified doses to persons in the vicinity of the facility and do not pose a risk to any other Member State. In addition, radioactive operational waste from the activities will remain unchanged and take place with previously commissioned facilities for waste management and final disposal.