Researchers have uncovered a fascinating revelation about the behavior of hydrogen atoms in irradiated gibbsite, a material used extensively during the Cold War-era plutonium production. This study, published in the journal Physical Chemistry Chemical Physics, sheds light on the impact of residual impurities on the stability of these hydrogen atoms, with significant implications for energy security and radioactive waste management.
Mystery solves the secret of hydrogen in irradiated gibbsite
Aluminum was used preferentially for fuel cladding material during the time of the Cold War at the US Department of Energy’s Hanford Site in Washington State. Fuel processing results in gooey byproducts which are stored under the ground in tanks, and this aluminum is probably present there as boehmite and gibbsite.
This research is of fundamental nature and deals with irradiated fuel wastes situations (i.e., one of the most complex and extreme conditions). Here we explore a complex between Al and trace species, the residues of synthetic precursors that might influence radical presence in gibbsite. They also tested irradiated boehmite, which is already known to capture and stabilize hydrogen. The implications of this study in terms of energy–security nexus, energy de-carbonization nexus and safe management and disposal of legacy-radioactive waste are far-reaching.
Small Amounts Of Impurities: The X-Factor For Hydrogen Atoms To Stay Broken
The results indicate that hydrogen atoms detected in gibbsite nanoplates induced by gamma radiation are related to some degree of residual contamination. Concomitantly the concentration of these hydrogen atoms decreases faster, because their lattice site are interstitial gibbsite layers instead of edge and surface sites like in boehmite. The authors suggest that such experimental evidence of different behavior for hydrogen atoms in gibbsite and boehmite can assist with understanding the extreme chemical complexity of radioactive waste.
This has generated expectations about the potential of this mineral for use in high-level waste repositories and nuclear power plants, the research recently published in The Journal of Physical Chemistry C concluded that ions remaining from different precursors (Al(NO3)3 or AlCl3) used during synthesis influence the generation and stabilization of gamma-radiation-induced hydrogen atoms inside gibbsite nanoplates . This work further explored the binding and desorption energies of hydrogen within boehmite, which will serve to both trap and stabilize hydrogen atoms in a structure.
Revealed structures: Diffuse Reflectance Infrared Fourier transform Spectroscopy and X-ray Photoelectron Spectroscopy
The IDD researchers used a range of analytical tools to determine the impact of impurities that remain in gibbsite on how hydrogen atoms are stored. Hydroxyl groups in gibbsite synthesized from nitrate and chloride, as well as nitrate in gibbsite form Al(NO3)3 was analysed by diffuse reflectance infrared Fourier transform spectroscopy. X-ray Photoelectron Spectroscopy also revealed the presence of chloride residuals in AlCl3-based gibbsite.
Although the fractions of these residual ions on the surface were ~0.4 atom % for nitrate and ~0.6 atom % for chloride, their concentrations far exceeded any amounts that had measurable effects on the bulk properties of gibbsite, yet this level was sufficient to affect material response to radiolysis. Hydrogen Atoms and electron paramagnetic resonance spectroscopy All doses contained hydrogen atoms (to a lesser or greater extent) in the Cl-gibbsite as quantified by the method of catalytic generation, which is less sensitive to anions such as OOH than direct EPR did. NADA was not present (or below limits of detection) at any sampling timepoint for NO3 -gibbsite by all methods used. This suggests that hydrogen atoms are produced for in both conditions, however, they only get stored when Nitrate is not present.
