A group of researchers from the HZDR Institute (Helmholtz Zentrum Dresden-Rossendorf), Germany, accidentally discovered a completely new stable form of plutonium. This unstable and radioactive element needs special measures during transportation, storage and disposal, and the discovery of German scientists may become a new way to solve the problems mentioned above.
The instability of plutonium makes it an incredibly powerful source of energy, on the one hand, and, on the other hand, a potentially destructive force that can cause an environmental disaster. Some of the plutonium isotopes can exist for tens of millions of years and it is easy to imagine what the contamination of groundwater, for example, with such isotopes will lead to. Therefore, scientists are constantly looking for new ways to more safely store, transport, and dispose of plutonium and its compounds. And just during such studies, scientists from HZDR accidentally found a new stable form.
One of the safest forms of plutonium is plutonium dioxide, which is a ceramic material that is insoluble in water and has a fairly high melting point. Plutonium dioxide nanoparticles can be prepared in a variety of ways, using various starting materials called precursors containing plutonium isotopes. German scientists in their experiments used precursors called Plutonium (VI) (Pu (VI)), dissolved in water and noticed very strange chemical reactions.
Pu (VI), during its conversion to plutonium dioxide, passed through a transition phase in which this material became solid and stable. Under normal conditions, pentavalent plutonium Pu (V) is neither solid nor stable material, therefore, what scientists had noticed, was attributed by them to the incorrect course of chemical reactions of plutonium dioxide synthesis.
“Every time we make nanoparticles from Pu (III), (IV) or (V) precursors, the reaction proceeds very quickly. But in this case we noticed a strange phenomenon somewhere in the middle of the path,” the researchers write, “Like scientists, we were very surprised by the chemists, but our results clearly indicated something new”.
In order to confirm some of the assumptions, the researchers used a Rossendorf Beamline X-ray spectrometer (ROBL). This device allows you to measure the energy of radioactive elements by irradiating them with x-ray radiation and measuring the intensity of their fluorescence. These studies confirmed the existence of a new Pu (V) phase, and the samples were re-tested after three months, which confirmed the stability of the new form of plutonium for a long time.
It is still not very clear what results the discovery will lead to. But scientists believe that now there is a need to revise some known and unknown effects that occur during long-term storage of nuclear fuel waste. “This is a rather complicated and difficult task, the solution of which now mainly uses theoretical premises, conjectures and assumptions. But the existence of a new solid and stable form of Pu (V) should be taken into account in all this,” the researchers write, “and this will certainly change all that we know about the behavior of plutonium under conditions that are specially created during storage of nuclear waste”.