Metoder för tjockleksmätning av kopparoxidskikt på kopparkapslar, samt tillverkning av referensprover

Sammanfattning: Swedish Nuclear Fuel and Waste Management Company, SKB, main mission is to manage and take care of the Swedish nuclear waste. The method chosen is to store the waste far down in the ground in capsules made of copper, which needs to be intact for 100 thousands years. Friction stir welding is used to seal the capsules, which causes oxidation due to heat, but is avoided by using gas protection. If this protection fails, SKB needs to be able to measure the thickness of the oxide to be able to determine if there is too much oxygen in the capsules, which can cause problems in the long run by making the capsules disintegrate and leaking nuclear waste. In this work different methods that SKB can use to measure the thickness of the copperoxide are examined. To find a method for thickness measurements several methods were examined through literature (Spectral-reflectance, Terahertz Time-Domain Spectroscopy, Laser absorption and usage of color). One of these was tested in practice, which was spectral-reflectance. Reference samples were manufactured with known oxide thickness to be used for callibration and teseting of the chosen instrument. The spectral-reflectance measurements were performed on the samples from the work which gave results that agreed with ellipsometry measurements that were made to verify the thickness of the oxides. Since spectral-reflectance worked on the samples and it is a non-contact and non-destructive method, it was the chosen method to be suggested to SKB.