Distribution of tritium and its compounds in the environment under normal conditions of operating of Kalininskaya nuclear power plant

Tritium is one of the most important dose-forming radionuclides that determine the radiation situation in the area where nuclear fuel cycle enterprises are located. At the same time, it is not possible to catch the tritium formed during the operation of a nuclear power plant using modern, efficient and cheap technologies. This causes an increase in its concentration in environmental objects and an increase in the contribution of technogenic tritium to the radiation load of the population. Therefore, the task of monitoring the formation of tritium during the operation of nuclear power plants, the content of tritium in emissions and discharges of nuclear power plants, as well as the distribution of this radionuclide in the environment is especially urgent today. The study aims to analyze the environmental pollution due to emissions and discharges of tritium from the Kalininskaya nuclear power plant, the process of spreading tritium by air, as well as the accumulation of this radionuclide in water bodies, soil and food products grown in the area of the nuclear power plant. The following methods, developed by the specialists of the Burnasyan Federal Medical Biophysical Center were used during the research: 1) "Method for determining the volumetric activity of organic and inorganic tritium compounds in water bodies by liquid scintillation spectrometry". 2) "Methodology for determining the concentration of organic and inorganic tritium compounds in the air of the environment and industrial premises". 3) "The method for determining the specific activity of tritium compounds in soil and vegetation" was developed and tested in the course of field studies at the Kalinin NPP. As a sample preparation we used the method based on burning a selected sample in a specialized Pyrolyser-6 Trio oven. All prepared counting samples were measured by liquid scintillation spectrometry on a counter Tri-Carb 3180TR/SL. On the basis of an integrated approach to assessing the content of tritium and its compounds in air, water, soil and food, an analysis of the formation of environmental pollution due to emissions and discharges of tritium from the Kalinin NPP was carried out. It is shown that the transport of emissions from the NPP by air and the wind direction prevailing in the territory of the NPP location have a significant importance in the formation of the contribution to the ingress of tritium into foodstuffs. The necessity of taking into account the ingress of tritium and its compounds with nuclear plant emissions into the environment in the task of optimization of radiation protection of the population under conditions of normal operation of NPP is shown.

Influence of Soil Depth on Sorption and Desorption Processes of Hexazinone

ABSTRACT: Herbicides with a high leaching capacity, such as hexazinone, tend to reach deeper soils more easily, where retention of the product affects its availability in the soil solution. Therefore, it is important to understand the behavior of hexazinone at a variety of soil depths. The objective of this research was to evaluate the sorption and desorption of hexazinone throughout the soil profile. The sorption and desorption processes of 14C-hexazinone [triazine-6-14C] at three soil depths (0-10, 10-20, and 20-30 cm) were evaluated by the equilibrium batch method, and the radioactivity of the herbicide was quantified by liquid scintillation spectrometry. Five different concentrations of hexazinone (0.12, 0.19, 0.25, 0.31, and 0.38 µg mL-1) in a methanol solvent were used. The concentrations of the herbicide in equilibrium and sorbed in the soil were adjusted by using isotherms according to the Linear, Freundlich, and Langmuir models. Hexazinone sorption at soil depths of 0-10, 10-20, and 20-30 cm showed decreasing Freundlich coefficients (Kf) with values of 0.18, 0.11, and 0.08 g (1-1/n) L1/n kg-1 (50.49, 47.58, and 46.37% sorbed), and in the desorption the Kf were 7.96, 7.93, and 9.82 g (1-1/n) L1/n kg-1 (26.17, 26.58, and 28.68% desorbed), respectively. The small difference in organic carbon content between soil depths was sufficient to affect hexazinone retention, interfering with the bioavailability of this product in the soil solution for weed control.

Preparation of 93Mo solution using proton irradiated Nb

93Mo is an important long-lived radionuclide in nuclear waste, and is required to be measured during the characterization of decommissioning waste. However, no commercial 93Mo solution is available to be calibrated and used as standard in the analysis of nuclear waste. This work presents a method for separation of 93Mo from Nb metal used in cyclotron as a target holder and irradiated with protons for long time. The separation of 93Mo from Nb matrix was implemented by combination of precipitation and chromatographic separation. The Nb matrix was first removed by precipitating oxides-hydroxides of Nb (e.g. Nb2O5) and then by Fe(OH)3 co-precipitation; Mo in the solution was purified using an alumina (Al2O3) column. A decontamination factor of ca. 105 was achieved for Nb. A pure carrier-free 93Mo solution was successfully prepared, and the 93Mo purity was verified by liquid scintillation spectrometry.

Sequential analysis of uranium and plutonium in environmental matrices by extractive liquid scintillation spectrometry

A methodology for sequential separation of uranium (U) and plutonium (Pu) followed by their estimation, using extractive liquid scintillation spectrometry was standardized for matrices like soil, fish and sediment. Various parameters for selective and efficient extraction and separation of Pu and U in the presence of interfering matrix elements with HDEHP bis(2-ethylhexy1) phosphoric acid as an extracting agent were investigated. Quenching effect of the various extracting reagents on resolution of α spectrum of analytes and reduction in these interferences is discussed in the current study. Standardized procedure gave about 91% of extraction of spiked Pu into the organic phase. Performance of the method was tested by separating and estimating U and Pu in International Atomic Agency (IAEA) certified reference materials like soil/sediment/fish.

Study of radiotoxic 210Po in Indian tobacco using liquid scintillation spectrometry

A fast radioanalytical method has been developed to measure 210Po in tobacco samples. After microwave digestion polonium is extracted quantitatively from a 1 M hydrochloric acid solution into a solution of triisooctylamine in toluene. The extract was measured by liquid scintillation counting in α mode. Caused by the high counting efficiency the counting time per sample can be reduced significantly compared to conventional α spectrometry, allowing for high sample throughput. The method was applied to 11 brands of cigarettes, beedis and or chewing tobaccos from India. Based on the resulting activity concentrations and typical consumption habits, annual and lifetime equivalent doses were calculated. They were found to be ~100–700 μSv/a or ~5–35 mSv, respectively.

Absorption, Translocation, and Metabolism of14C-Halosulfuron in Grafted Eggplant and Tomato

Grafted plants are a combination of two different interspecific or intraspecific scion and rootstock. Determination of herbicidal selectivity of the grafted plant is critical given their increased use in vegetable production. Differential absorption, translocation, and metabolism play an important role in herbicide selectivity of plant species because these processes affect the herbicide amount delivered to the site of action. Therefore, experiments were conducted to determine absorption, translocation, and metabolism of halosulfuron in grafted and non-grafted tomato and eggplant. Transplant type included non-grafted tomato cultivar Amelia, non-grafted eggplant cultivar Santana, Amelia scion grafted onto Maxifort tomato rootstock (A-Maxifort) and Santana scion grafted onto Maxifort rootstock (S-Maxifort). Plants were treated POST with commercially formulated halosulfuron at 39 g ai ha-1followed by14C-halosulfuron under controlled laboratory conditions. Amount of14C-halosufuron was quantified in leaf wash, treated leaf, scion shoot, rootstock shoot, and root at 6, 12, 24, 48, and 96 h after treatment (HAT) using liquid scintillation spectrometry. No differences were observed between transplant types with regard to absorption and translocation of14C-halosulfuron. Absorption of14C-halosulfuron increased with time, reaching 10 and 74% of applied at 6 and 96 HAT, respectively. Translocation of14C-halosulfuron was limited to the treated leaf, which reached maximum (66% of applied) at 96 HAT, whereas minimal (<4% of applied) translocation occurred in scion shoot, rootstock shoot, and root. Tomato plants metabolized halosulfuron faster compared to eggplant regardless of grafting. Of the total amount of14C-halosulfuron absorbed into the plant, 9 to 14% remained in the form of the parent compound in tomato compared with 25 to 26% in eggplant at 48 HAT. These results indicate that grafting did not affect absorption, translocation, and metabolism of POST halosulfuron in tomato and eggplant.