New knowledge about plutonium calms scientists

New analyses from KTH in Stockholm are creating order in the uncertainty that has prevailed for the last four years about how plutonium dioxide, one of the most important radioactive compounds in nuclear waste, behaves when it comes into contact with water. The findings are being published in the latest issue of Nature Materials.

In January 2000 an article was published in the American scientific journal Science. A research team had discovered that plutonium dioxide, PuO2, quite unexpectedly could be transformed by oxidation to form a new stable compound PuO2,27.

This sparked heated discussions and a great deal of uncertainty in the scientific community, since the world was now facing a new radioactive compound with unknown characteristics.

The consequences of this would be that hazardous nuclear waste was probably much more easily soluble in water that was previously thought, and thereby much more unstable. Previous risk assessments were turned on end.

A research team at the Royal Institute of Technology (KTH) in Stockholm, with scientists from KTH, Uppsala University, and a research institute in Budapest were commissioned by SKB, the Swedish Nuclear Fuel and Waste Management Company, to study this. It has taken four years, and advanced calculations have been carried out in order to explain the earlier findings. The results are considered to be of vital importance.

“It’s good news. It seems that this compound PuO2,27, is not stable. It can only be created temporarily under special conditions, which means that there is no reason to revise previous risk analyses. We have filled in a few gaps in our knowledge and found an explanation for the findings of the other scientists,” says Pavel Korzhavyi, a researcher at KTH Materials Science.

The team’s findings are based on computer simulations, and neither Pavel nor his colleagues have been in contact with plutonium.