Doctoral dissertation

The colour of radioactivity: how optics made in Tampere can see invisible alpha radiation

Thomas Kerst
Why is it so expensive to shut down a nuclear power plant? And does it really have to take tens of years to do so? The clever use of the radioactive glow suggests that there might be safer, faster and more economical ways to go about nuclear decommissioning.

If the journalists of the British newspaper The Guardian are to be believed, then the European energy companies (and their unsuspecting customers) are “facing [a] €253bn nuclear waste bill”. The authors refer to the estimated amount of money it costs to shut down the many nuclear power plants that will soon go out of service. The estimate is not unrealistic when considering that the well-managed and unproblematic Finnish Loviisa plant already incurs costs of about €359m at the end of its lifetime. Even though shutting down a power plant like this might not be a problem, its price tag most certainly is one.

What drives the price is the detection and safe removal of radioactive waste. It is not the removal of nuclear fuel that is (overly) expensive, nor is its transport to places like Olkiluoto. It is the safe and careful removal of every bit of nuclear material that is extremely expensive. And this careful removal is necessary. It ensures that after the power plant is gone, no radioactive waste or nuclear material is left behind.

Even though removing nuclear material makes it is necessary to maintain high security standards, it is not necessary to rely on expensive and time-consuming procedures to enforce them. In the Photonics Laboratory at Tampere University, researchers developed a technology that promises to make the removal safer, faster and cheaper. The technology finds nuclear material by looking for the radioactive glow that appears around alpha radiation. Doctoral student Thomas Kerst argues and demonstrates that a specific shade of ultraviolet light (the colour of radioactivity) is best suited to do the job.

The doctoral dissertation of MSc Thomas Kerst in the field of Photonics titled Stand-Off Detection of Alpha Radiation in Nuclear Facilities will be publicly examined in the Faculty of Engineering and Natural Sciences at Tampere University at 12 o’clock on Friday 4th of October in Hervanta camus Rakennustalo building room RG202, Korkeakoulunkatu 5, 33720 Tampere. The Opponent will be Dr Lars René Lindvold of the Technical University of Denmark. The Custos will be professor Juha Toivonen of the Photonics Laboratory.

The dissertation is available online at the

Photo: Jaakko Muikku