Development of Methods to Evaluate Several Levels of Uranium Concentrations in Drainage Water Using Total Reflection X-Ray Fluorescence Technique

As a country's law stipulates the effluent standard uranium concentration in drainage water, the uranium concentration must be determined when drainage water is released from a uranium handling facility, such as the Fukushima Daiichi nuclear power plant. The maximum allowable limit for uranium release at each facility is defined taking into consideration the situation of the facility, such as 1/10 to 1/100 of this effluent standard value. Currently, the uranium concentration of drainage water is commonly determined by α-particle spectrometry, in which several liters of drainage water must be evaporated, requiring about half of a day followed by 2–3 h of measurements, due to the low specific radioactivity of uranium. This work proposes a new methodology for the rapid and simple measurement of several levels of uranium in drainage water by a total reflection X-ray fluorescence (TXRF) analysis. Using a portable device for TXRF measurements was found to enable measurements with 1/10 the sensitivity of the effluent standard value by 10 times condensation of the uranium-containing sample solution; a benchtop device is useful to measure uranium concentrations <1/100 of the effluent standard value. Therefore, the selective usage of methods by a portable and benchtop devices allows for screening and precise evaluation of uranium concentrations in drainage water

Protective Efficacy of Neutralizing Monoclonal Antibodies in a Nonhuman Primate Model of Ebola Hemorrhagic Fever

Ebola virus (EBOV) is the causative agent of severe hemorrhagic fever in primates, with human case fatality rates up to 90%. Today, there is neither a licensed vaccine nor a treatment available for Ebola hemorrhagic fever (EHF). Single monoclonal antibodies (MAbs) specific for Zaire ebolavirus (ZEBOV) have been successfully used in passive immunization experiments in rodent models, but have failed to protect nonhuman primates from lethal disease. In this study, we used two clones of human-mouse chimeric MAbs (ch133 and ch226) with strong neutralizing activity against ZEBOV and evaluated their protective potential in a rhesus macaque model of EHF. Reduced viral loads and partial protection were observed in animals given MAbs ch133 and ch226 combined intravenously at 24 hours before and 24 and 72 hours after challenge. MAbs circulated in the blood of a surviving animal until virus-induced IgG responses were detected. In contrast, serum MAb concentrations decreased to undetectable levels at terminal stages of disease in animals that succumbed to infection, indicating substantial consumption of these antibodies due to virus replication. Accordingly, the rapid decrease of serum MAbs was clearly associated with increased viremia in non-survivors. Our results indicate that EBOV neutralizing antibodies, particularly in combination with other therapeutic strategies, might be beneficial in reducing viral loads and prolonging disease progression during EHF

Screening of uranium surface contamination on demolition debris by TXRF analysis

With the progressing decommissioning of the Fukushima Daiichi Nuclear Power Plant, the possibility that demolition debris could be contaminated with uranium will increase. Total reflection X-ray fluorescence (TXRF) analysis has been used to detect trace uranium in water [1-3]. Thus, it is likely that TXRF analysis of acid elution solution of demolition debris samples could be used to evaluate uranium surface contamination on demolition debris. In this study, we developed a methodology for screening of uranium surface contamination on demolition debris using TXRF analysis. As a model of surface shavings of contaminated demolition debris, a series of uranium solutions with different concentrations were placed on 5 g of crashed concrete/soil mixtures and dried. Subsequently, 20 mL of 4 M nitric acid solution was added to the samples and shaken for 30 min. After filtration using a hydrophilic polyvinylidene difluoride membrane (pore size of 0.1 µm), chromatography resin separation was performed. During this step, uranium was separated from the native elements of the soil and concrete including iron (present in soil and concrete in large concentrations), calcium (present in concrete in large concentrations), and rubidium whose Kα line overlaps that of the U Lα line. Bromine, with a Kβ line that also overlaps the U Lα line, remained in solution more than the other elements tested and the U Lα peak was easily separated from the Br Kβ peak by Gaussian fitting. For the TXRF measurements, 190 μL of the sample solutions were mixed with 10 μL of a 100 μg/mL gallium standard. Subsequently, 10 μL of the resulting mixture was dropped onto a fluorine resin-coated glass slide and dried for ~5 min using a heater at 80 °C. TXRF measurements were performed using a benchtop-type TXRF instrument (NANOHUNTER-II, Rigaku Corporation, Tokyo, Japan). The uranium contents of the sample solutions were higher than the spiked uranium contents due to uranium elution from the soil and concrete. This method will be useful for screening of contaminated demolition debris. This research project was conducted as regulatory supporting research funded by the Secretariat of Nuclear Regulation Authority (S/NRA/R), Japan.[1] Matsuyama et al., J. Nucl. Sci. Technol. 54, (2017), 940.[2] Yoshii et al., Spectrochim. Acta Part B 148, (2018) 183.[3] Matsuyama et al., Spectrochim. Acta Part B 149, (2018), 35.18th International Conference on Total Reflection x-ray Fluorescence Analysis and Related Methods (TXRF2019

X-ray Fluorescence-based Screening Method for Uranium Contamination

Uranium, which is used as nuclear fuel, is a radioactive material, and screening for uranium contamination is often performed by radiation measurements. However, a method targeting the number of atoms is more effective than radiation measurements for detecting uranium, which is a long-half-life nuclide with very low specific radioactivity. X-ray fluorescence analysis is one such analytical method that is suitable for screening measurements because of the simple pretreatment required. In this article, the properties of uranium and the superiority of X-ray fluorescence analysis as a screening method for uranium contamination are described first. Furthermore, we provide a comprehensive overview of screening methods based on X-ray fluorescence (XRF) analysis for uranium-contaminated wounds, on the basis of our recent studies. These methods can be used in radiation emergency medicine. In addition, we discuss methods based on total reflection X-ray fluorescence (TXRF) analysis for analyzing uranium-contaminated drainage water which will be found in the decommissioning field of Fukushima Daiichi Nuclear Power Plant