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Occupational radiation exposure has been one of the most important issues in light water reactors. The radiation source is dominantly radioactive cobalt incorporated in oxide film on structural materials. To lower radiation intensity, zinc injection has been implemented widely in light water reactors. Application of the zinc injection leads to incorporation of zinc in the oxide film and changes in the oxide film. Chemical decontamination is applied after shutdown and removes the radioactive cobalt. When the chemical decontamination was applied to plants which experienced the zinc injection, decontamination factor was sometimes lower than before the zinc injection. Then, in the present work thermodynamic solubility of divalent cobalt and divalent zinc was calculated with a thermodynamic code, assuming typical conditions of oxidizing steps of the chemical decontamination. It has been concluded that the solubility limit of divalent cobalt is 22 to 26 times higher than that of divalent zinc under any oxidizing condition. These figures are consistent with the plant data observed during the application of the chemical decontamination. It has been concluded that the oxidizing step of the typical chemical decontamination methods are suitable condition for effective dissolution of cobalt and less effective dissolution of zinc.

Base metal corrosion forms a significant issue during the chemical decontamination of the primary coolant loop in nuclear power plants as it is directly related to the economic and safety viability of decommissioning. In this technical note, potentiodynamic evaluations of several base metals (304 stainless steel, SA106 Grade B carbon steel, and alloy 600) were performed to determine their corrosion behavior during the hydrazine (N2H4)-based reductive ion decontamination (HyBRID) process. The results suggested that N2H4 protected the surface of the base metals in the HyBRID solution, which is primarily composed of H2SO4. The corrosion resistance of the carbon steel was further improved through the addition of CuSO4 to the solution. The corrosion rate of carbon steel in the H2SO4-N2H4-CuSO4 solution was lower than that exhibited in an oxalic acid solution, a commonly used reaction medium during commercial decontamination processes. These results indicate the superiority of the HyBRID process with respect to the base metal stability.

Surface chemistry evaluation is crucial in assessing the efficacy of chemical decontamination products for titanium implants. This study aimed to investigate the effectiveness of chemical decontamination solutions in cleaning a contaminated dental implant surface and to evaluate the potential of combining Pluronic gel with hydrogen peroxide (NuBone®Clean) by evaluating pellicle disruption and re-formation on implant surfaces. In addition, ensuring safety with in vitro and human testing protocols. X-ray Photoelectron Spectroscopy (XPS) was utilised for surface analysis. All the tested gels had some effect on the surface cleanness except for PrefGel®. Among the tested chemical decontamination candidates, NuBone®Clean demonstrated effectiveness in providing a cleaner titanium surface. Furthermore, none of the tested chemical agents exhibited cytotoxic effects, and the safety assessment showed no adverse events. The results of this study highlight the significance of conducting comprehensive evaluations, encompassing safety and efficacy, before introducing new chemical agents for dental treatments. The findings suggest that NuBone®Clean shows potential as a chemical decontamination solution for implant surfaces. However, further investigation through randomised clinical trials is necessary. By adhering to rigorous testing protocols, the development of safe and efficient chemical decontamination strategies can be advanced, benefiting patients and promoting progress in implant dentistry.

Decontamination for military purposes represents the process of removing/neutralizing of [...]

Chemical, biological, radiological, and nuclear (CBRN) decontamination is the removal of CBRN material from equipment or humans. The objective of the decontamination is to reduce radiation burden, salvage equipment, and materials, remove loose CBRN contaminants, and fix the remaining in place in preparation for protective storage or permanent disposal work activities. Decontamination may be carried out using chemical, electrochemical, and mechanical means. Like materials, humans may also be contaminated with CBRN contamination. Changes in cellular function can occur at lower radiation doses and exposure to chemicals. At high dose, cell death may take place. Therefore, decontamination of humans at the time of emergency while generating bare minimum waste is an enormous task requiring dedication of large number of personnel and large amount of time. General principles of CBRN decontamination are discussed in this review with emphasis on radiodecontamination.