Effects of electrical fields on final storage of nuclear fuel
Swedish Nuclear Fuel and Waste Management Company, SKB, is constructing a facility for the final storage of spent fuel from nuclear power plants. The facility is being built to last 100 000 years and safety is essential. Swerea has studied how electrical fields in the bedrock affect corrosion of the storage capsules.
In collaboration with Swerea, SKB has calculated how corrosion of copper capsules, intended for use in the final storage of nuclear fuel, will be affected by electrical fields. Results show that the fields cause an insignificantly higher capsule corrosion rate.
Cause for corrosion
Current estimates of corrosion are based on diffusion of oxygen and sulphides. As a complement to the study, Swerea has also performed calculations to assess the corrosion resulting from electrical fields in the bedrock.
There is a direct current connection between Sweden and Finland that can be powered with only a single cable. The return current goes through water and bedrock. Electrical fields that occur around the system’s electrodes can, in principle, affect capsule corrosion.
Measurement data for accurate calculations
Calculations have been made based on measurements and simulations. The calculations also took into account that the system’s electrodes might be moved closer to the storage facility and that the seawater level may change in the future.
“Swerea has worked in this field for quite some time, building up knowledge and a bank of measurement data that make calculations more accurate,” says Claes Taxén, researcher at Swerea.