Nuclear waste to be scanned before final disposal

At Olkiluoto in Eurajoki, preparations are underway to start the disposal of spent nuclear fuel in the Finnish bedrock next year – as the first place in the world. After use, nuclear fuel becomes strongly radiating and dangerous waste. It contains a large amount of uranium and plutonium, which are building blocks for nuclear weapons. All these materials must be intact when the fuel rods are stored in their final deposit. This is why they must be meticulously and dependably measured before depositing them.

All the important information must be gathered before the final disposal. The measurements must also be stored in a way that will be accessible and understandable to human beings for thousands, even hundreds and thousands of years. For her doctoral thesis, Riina Virta has studied measuring methods for nuclear waste at the University of Helsinki in cooperation with the Helsinki Institute of Physics (HIP). Virta also works as an inspector in the nuclear materials safeguards section of the Radiation and Nuclear Safety Authority.

In her thesis work, Riina Virta developed a PGET device, i.e. an imaging method called passive gamma emission tomography, which measures the gamma radiation emitted by spent nuclear fuel. Nuclear fuel consists of rods, a few metres long and containing uranium, which are gathered into an assembly to act as a fuel element. The PGET instrument can produce an exact cross-section image of the fuel assembly.

Source: University of Helsinki