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Gamma irradiation method has been applied to produce paramagnetic spherically shaped single crystals tricobalt tetraoxide (Co 3 O 4) nanoparticles from cobalt oxyhydroxide sols, in alkaline medium pH ~ 12. The present investigation has proven the efficiency of gamma rays in inducing changes in structure and morphology of the sols prepared before irradiation. Characterization techniques so far discussed in this study revealed that the sol product prepared before irradiation corresponded to the standard cobalt(III) oxyhydroxide, CoO(OH) , which, under gamma irradiation, was transformed to tricobalt tetraoxide, Co 3 O 4 , with an average particle size of ~ 30-45 nm.

Two severe accident scenarios are investigated in this paper as they have never been considered previously in the safety analysis report (SAR) of the Congo TRIGA Mark II research reactor (TRICO II) in Kinshasa, the Democratic Republic of Congo. The source term is derived from the reactor core after two postulated accidents: (1) a large plane crash with total destruction of the reactor building and (2) full damage of one fuel element while the reactor building remains intact. Total effective dose (TED), after core inventory, and dose profiles to human organs are derived to assess the operational safety of the reactor. Results from the study will be used to upgrade the current SAR of the reactor as the reactor safety and licensing concepts are changing over the years; the knowledge and lessons learned from the past experience are being updated accordingly with the available data. TEDs to workers of the facility show that higher values are obtained at areas near the source term at the time of the plane crash accident, which dies out as quickly as the plume is carried away following predominant meteorological conditions at the site. The situation with one fuel element totally damaged poses no threat as far as radiation protection is concerned and reveals a maximum TED of 1.30×10−7  mSv at 100 m from the reactor core. This shows that the operation of this type of research reactor is reliable and safe.

Magnetic cobalt ferrite has wide spread applications, especially as catalyst for the conversion of alkenes to related aldehydes. Despite several studies found in the literature concerning the fabrication of cobalt ferrite, none has reported on gamma irradiation as a tool for the synthesis of submicrometer sized inverse spinel CoFe 2 O 4 . The actual investigation reports on the application of γ-irradiation method for the synthesis of superparamagnetic CoFe 2 O 4 , using metal salts precursors and organic reagents. The material fabrication occurs in two main steps as sofar described. The obtained powder was isolated after irradiation and was characterized using X-ray diffraction method, transmission electron microscopy, FT-IR spectroscopy, Raman spectroscopy, UV-visible measurements and vibrating sample magnetometer. Furthermore, the X-ray diffraction data revealed the presence of a reverse spinel structure. The magnetic properties of the fabricated powder exhibited the measured lower coercivity and remanence, demonstrating that the spinel powders are made of superparamagnetic particles and finally, to gain information about the photocatalytic properties of the synthetized material, the room temperature recorded optical measurements for different samples proved that these powder materials may probably exhibit new opportunities which could improve their high photocatalytic efficiency under visible light. The prepared materials could be used as potetentiel candididates for the oxidation of organics compounds.