Synthesizing nuclear power plant fouling with fractal characteristics enables an in-depth study of concerned nuclear safety issues

Fouling deposit on nuclear fuel cladding causes wick boiling and boron hideout, resulting in localized corrosion and power shift with great potential security and economic risks. Herein, a cost-effective time-saving adjustable reproduction method combining sol-gel with ceramic sintering is presented to enable wide coverage of fouling's morphologies and microstructures. Based on fractal analysis, structurally self-similar fouling deposits from different reactors conform to proposed porosity-fractal dimension law under 3% relative error. Wick boiling and boron hideout numerical simulation based on fractal dimension is implemented to treat different morphologies and structures in a unified way. Cladding surface underneath fouling deposit has a maximum 9.243 K temperature increasement due to thermal resistance, and H3BO3 is concentrated 11.274 times by mean of wick boiling, causing Li2B4O7 precipitation under extreme conditions with low porosity and high heat flux. The insights in this study provide a precise approach for quantitative evaluation of localized corrosion and power shift.

Oxidative dissolution of Cr-doped UO2 nuclear fuel

Alternative UO₂ nuclear fuels, incorporating Cr as a dopant, are currently in use in light-water reactors. Dissolution experiments using Cr-doped UO₂, performed as a function of Cr content in a simplified groundwater solution and under oxic conditions, established that the addition of Cr to the UO₂ matrix systematically reduced the normalised dissolution rate of U at 25 and 40 °C. This effect was most notable under dilute solution conditions, and is the result of galvanic coupling between Cr and U, resulting from the presence of Cr²⁺ in the UO₂ matrix, as corroborated by activation energy determination. Under conditions of solution saturation, where schoepite ((UO₂)₈O₂(OH)₁₂·(H₂O)₁₂) and Na₂U₂O₇·6H₂O were identified as secondary phases, the rate of U dissolution was invariant with Cr content. Moreover, at 60 °C, the trend was reversed and the rate of U dissolution increased with increasing Cr content. Under these conditions, other factors, including U solubility or bicarbonate-surface interactions, exert a stronger influence on the U dissolution kinetics than Cr. Increased grain size, a feature of Cr-doped UO₂ fuel, was also found to reduce the normalised dissolution rate of U. In establishing the mechanisms by which Cr dopants influence UO₂ fuel dissolution, it can be concluded that, overall, Cr-doped UO₂ nuclear fuel possesses similar dissolution kinetics to undoped UO₂ fuel, giving confidence for its eventual disposal in a geological facility.

On the consensus nomenclature rules for radiopharmaceutical chemistry - Reconsideration of radiochemical conversion

Radiochemical conversion is an important term to be included in the "Consensus nomenclature rules for radiopharmaceutical chemistry". Radiochemical conversion should be used to define reaction efficiency by measuring the transformation of components in a crude reaction mixture at a given time, whereas radiochemical yield is better suited to define the efficiency of an entire reaction process including, for example, separation, isolation, filtration, and formulation.

Consensus nomenclature rules for radiopharmaceutical chemistry - Setting the record straight

Over recent years, within the community of radiopharmaceutical sciences, there has been an increased incidence of incorrect usage of established scientific terms and conventions, and even the emergence of 'self-invented' terms. In order to address these concerns, an international Working Group on 'Nomenclature in Radiopharmaceutical Chemistry and related areas' was established in 2015 to achieve clarification of terms and to generate consensus on the utilisation of a standardised nomenclature pertinent to the field. Upon open consultation, the following consensus guidelines were agreed, which aim to.