Tritium Compounds Research Articles

(Invited) Effect of Gaseous Tritium Environments on Betavoltaic Device Longevity

Direct betavoltaic energy conversion is a specialized energy harvesting technology, converting beta radiation from a radiation source directly into electricity using a semiconductor. Of the most common beta emitting isotopes, tritium betavoltaics hold promise owing to the high specific activity of solid tritium compounds, low shielding requirements and relatively high availability. Betavoltaic devices offer great promise to produce continuous quantities of nanowatt to microwatt power over the course of several years, particularly for low-power sensor, medical, and space applications where sunlight is too sparse for solar cell use or where battery replacement is challenging.Canadian Nuclear Laboratories (CNL) is currently developing betavoltaic devices based on tritium. CNL has unique facilities to produce, fabricate and test betavoltaic devices. Computational techniques have been used to address challenges of longevity and electron-hole pair generation in semiconductor materials, in particular (In,Ga)P. Long-term studies on test wafers in different tritium-containing environments and the effects on power output and longevity will also be discussed.

СРАВНИТЕЛЬНОЕ ИССЛЕДОВАНИЕ ИЗМЕНЕНИЙ КОЛИЧЕСТВА ФОКУСОВ γH2AX И 53BP1 В МЕЗЕНХИМАЛЬНЫХ СТРОМАЛЬНЫХ КЛЕТКАХ ЧЕЛОВЕКА, ИНКУБИРОВАННЫХ С 3Н-ТИМИДИНОМ ИЛИ ТРИТИРОВАННОЙ ВОДОЙ

Purpose: Comparative study of changes in the number of foci of DNA (DSB) marker proteins (γH2AX and 53BP1) in human mesenchymal stromal cells (MSCs) incubated with 3H-thymidine or HTO for 24, 48, and 72 h. Material and methods: We used the primary culture of human MSCs of passage 5–6, obtained from the collection of LLC “BioloT” (Russia). A sterile solution of 3H-thymidine or HTO with a specific activity of 100 to 400 MBq/l was added to the nutrient medium and incubated under standard conditions of a CO2 incubator for 24, 48, and 72 hours. To quantify γH2AX foci and the proportion of proliferating cells using antibodies to γH2AX, 53BP1 and Ki67 (a marker protein for cell proliferation), were used, respectively. Statistical analysis of the obtained data was carried out using the statistical software package Statistica 8.0 (StatSoft). To assess the significance of differences between samples, Student’s t-test was used. Results: Incubation of MSCs with 3H-thymidine with a specific radioactivity of 100-400 MBq/l in the first 24 hours leads to a dose-dependent increase in the number of γH2AX and 53BP1 foci. With a further increase in the incubation time to 48 h and 72 h, a saturation effect is observed ‒ the number of foci reaches a plateau. A statistically significant increase in the number of γH2AX and 53BP1 foci in MSCs incubated with HTO was observed only in actively proliferating cells during the first 24 h of incubation in a medium with specific radioactivity of 300 and 400 MBq/l, after which, with a decrease in proliferative activity, it decreased to control values. Calculations made on the basis of the results of a quantitative analysis of γH2AX and 53BP1 foci after 24 h of incubation of MSCs with tritium compounds obtained in the course of the work show, that under the influence of 3H-thymidine ~ 6 times more DNA double-strand breaks are induced than under the influence of HTO.

Ведущая роль турбулентной диффузии в процессах атмосферного рассеяния трития в зоне влияния ядерного реактора

Previously carried out measurements of tritium activity in surface waters or snow with a 10–1000x excess over the background away from industrial sites of nuclear industry enterprises cannot be associated with technological accidents. They fully comply with the standard technological regime peculiar to a specific design of a nuclear reactor. It is shown that the intensity of dispersion of tritium compounds is mainly responsible for turbulent diffusion in “the flare” of the exhaust pipe, even during calm. This fact can be used to organize quantitative control of emissions to atmosphere during the year.

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.

Study on potential energy curves and ro-vibrational energies of DT, HT and T2 molecules

Accurately monitoring and effectively controlling the tritium compounds based on their ro-vibrational energy structure are important issues in various nuclear systems. Because of their radioactivity, it is difficult to obtain the corresponding energies directly through experiments. In this paper, the potential energy curves and the corresponding ro-vibrational full spectrum of DT, HT and T2 systems are derived by ab initio methods. However, it is difficult to verify the reliability of the calculated results due to the lack of direct experimental support. Therefore, a data-driven reliability analysis method is proposed, which can confirm the reliability by extracting information from the relevant calculations and multiple experimental data (the vibrational level, rotational level, and molar heat capacity) of similar systems (HD, H2, D2). The results show that: 1) The potential energy curves obtained by the ab initio method can provide the full ro-vibrational energy spectrum with an accuracy of approximately 10 cm−1; 2) Macroscopic heat capacity information can be used to distinguish and calibrate the overall reliability of microscopic ro-vibrational energies; 3) For the isotopic energy level structure of hydrogen, the influence of isotopes is mainly mass effect.

К ВОПРОСУ О ДОЗЕ ТРИТИЯ НА КЛЕТОЧНОМ УРОВНЕ

Purpose: To adapt traditional method of soft beta emitters’ dose calculation to the individual biological cells, to estimate the value of absorbed dose-rate factors for different tritium compounds on a cellular level. Material and methods: Approximation for point-source function obtained by L.V. Timofeev, G.B. Radzievsky et al. was used to adapt macroscopic beta-particle dosimetry methods to the area of subcellular structures. Results: Using the introduced concept of irradiated cell model base states the analytical expressions for absorbed dose in subcellular structures were suggested for non-uniform activity distributions of soft beta emitters in human tissue. The values of absorbed dose-rate factors for the case of organically bounded tritium confined to the nucleus (1.8 mGy/decay for 3H-thymidine) and for the case of tritiated water uniformly distributed throughout tissue (3.510-3 mGy/decay) were obtained. Conclusion: It can be assumed that traditional method of soft beta emitters’ dose calculation is adapted to the individual biological cells. The proposed methodology is supposed to be used in the future when constructing, based on experimental data, a biokinetic model of the intake of tritium organic compounds in the human body.

Tritium in the urine of the Mayak PA workers in the period from 2017 to 2019

Objectives. To define the levels of volume activity of tritium compounds and fraction of organically bound tritium in urine of chemical production workers of “Mayak Production Association” in present-day conditions; to identify the relationship between volume activity levels and professional occupation (department and profession). Material and methods. 245 urine samples from 171 workers of Mayak Production Association tritium production facility were collected in the period from 2017 to 2019. Volume activity of tritium compounds was measured by liquid scintillation method using spectrometer Quantulus-1220. The samples were distilled or dried and then combusted using an automatic preparation and oxidization system Sample Oxidizer A307. The “R” software was used for statistical analysis and for processing the measurement results and occupational factors. Chaddok’s scale was applied to determine the degree of correlation. The significance level was taken equal to 5%. Results. The value of total tritium volume activity in the urine and tritium volume activity in the water phase varied within 4 orders of magnitude (from ~30 Bq/dm3 to ~250 kBq/dm3). The value of volume activity of organically bound tritium in the urine varied within 2 orders of magnitude (from ~6 Bq/dm3 to ~3000 kBq/dm3). The fraction of organically bound tritium in the urine of the workers was within the range from 0,07% to 74%, and did not differ statistically significantly from lognormal distribution with parameters GM=2,7% and GSD=3,7. Very high rank correlation was detected between total volume activity of tritium compounds and tritium volume activity in the water phase in the urine. Noticeable rank correlations were detected between the total volume activity of tritium compounds in the urine and volume activity of organically bound tritium, as well as between tritium volume activity in the water phase and volume activity of organically bound tritium in the urine. The total tritium volume activity and tritium volume activity in the water phase in the urine of the workers of the 1st department and of the analytical laboratory of Mayak Production Association tritium production facility were statistically significantly higher than in the workers of the 2nd department according to median values. Statistically significant differences between medians of the total tritium volume activity in the urine and tritium volume activity in the water phase related to profession were observed only in the workers in the 1st department. Conclusion. Estimation of tritium volume activity in the water phase by the level of total tritium volume activity in the urine without sample preparation is possible with 95% reliability within limits of one order of magnitude towards the model value. Estimation of volume activity of organically bound tritium in the urine without sample preparation by the level of total tritium volume activity in the urine without sample preparation is possible with 95% reliability within limits of two orders of magnitude towards the model value. The effect of occupational factors to the levels of volume activity of tritium compounds in the urine of Mayak Production Association professional workers was detected.

DETERMINING CONTRIBUTION OF 3Н TO RADIATION EXPOSURE OF POPULATION AND PERSONNEL WHEN ENTERING WITH AIR AT THE TERRITORY OF SEMIPALATINSK TEST SITE

The paper provides tritium (3Н) concentrations in atmospheric air in the venues of tunnels at the «Degelen» testing site of Semipalatinsk Test Site (the STS). Tritiated water (НТО) and gaseous tritium compounds (НТ) in air environment were registered in air environment both at the «Degelen» testing site and beyond its boundaries. Based on the data obtained, contribution of 3Н entering with air into radiation exposure of personnel and population was determined through the example of the «Degelen» testing site. It was found, that contribution of 3Н to radiation exposure of the personnel (inhalational intake), carrying out works in the venues with the maximum concentration of 3Н in the air does not exceed 1%. Contribution of 3Н to the radiation exposure of population, performing economic activities beyond the «Degelen» site, in the venues of streamflows with high concentration of 3Н in water and in air will be approximately 10%.

Биологические эффекты органических и неорганических соединений трития

The review represents comparative data on the biological effects of inorganic (HTO) and organic (OBT) compounds of tritium at the molecular, cytogenetic and system levels. The data of the relative biological effectiveness (RBE) of OBT and HTO depending on their distribution in the cells and tissues of the body are presented. Experimental studies show that the calculation of the RBE of tritium compounds at different levels of organization leads to contradictory data. Such observation is associated with the interaction both of HTO and OBT with critical biomolecules in the cells as well as the proliferative activity of different cells and tissues. The experiments revealed that the effectiveness of OBT is much higher than the HTO which is associated with their rapid inclusion in the critical biomolecules such as proteins and DNA with the further formation of a significant biological effect. Based on the recently obtained data in different laboratories on the effect of tritium compounds at the molecular and cellular levels, it is concluded that a new approach for HTO and OBT risk assessment is necessary.

Comparative Analysis of the Formation of γH2AX Foci in Human Mesenchymal Stem Cells Exposed to 3H-Thymidine, Tritium Oxide, and X-Rays Irradiation.

We performed a comparative study of the formation of γН2АХ foci (a marker of DNA doublestrand breaks) in human bone marrow mesenchymal stem cells after 24-h incubation with 3Н-thimidin and tritium oxide with low specific activities (50-800 MBq/liter). The dependence of the number of γH2AX foci on specific activity of 3H-thymidine was described by a linear equation y=2.21+43.45x (R2=0.96), where y is the number of γH2AX foci per nucleus and x is specific activity in 1000 MBq/liter. For tritium oxide, the relationship was described by a linear equation y=2.52+6.70x (R2=0.97). Thus, the yield of DNA double-strand breaks after exposure to 3H-thymidine was 6.5-fold higher than after exposure to tritium oxide. Comparison of the effects of tritium oxide and X-ray radiation on the yield of DNA double-strand breaks showed that the relative biological efficiency of tritium oxide in a dose range of 3.78-60.26 mGy was 1.6-fold higher than that of X-ray radiation. Improvement of the methods of analysis of DNA double-strand breaks repair foci is highly promising in the context of creation of highly sensitive biodosimetry technologies for tritium compounds in humans.

Measurement of tritium with plastic scintillators in large vials of a low background liquid scintillation counter: an organic waste-less method

The tritium compounds, tritiated water as a volatile compound and 3H-methionine as a non-volatile compound, were measured with two types of plastic scintillators (PSs) using a low background liquid scintillation counter (LSC). It is advantage that minimal organic waste is generated when a plastic scintillator is used for LSC measurement. The effect of large vials on counting efficiency, plasma effects with three types of plasma devices for PS-sheets, the effect of UV-light on PS-pellets, the relationship between the activity and the count rate, and the detection limits of tritium were studied with respect to the development of large-scale measurement systems.

Leaching Tests of the Tritium Waste Immobilized in New Cement Mixtures

The study was conducted in order to determine the immobilization performance of low-level tritium waste in new cement mixtures. The grouts analyzed are fine mortars, fluid, self- compacting, with flowability, able to fill the smallest gaps in the solid waste container. The grouts curing showed compact and structural integrity without pores and cracks, so as to ensure radioactive tritium waste encapsulation.Two types of solid/liquid tritium radioactive waste with known tritium activity have been prepared: one type containing a hydrophilic tritium compound and the other one a hydrophobic tritium compound.The tritium waste was mixed with three different types of grout and poured in a cylindrical mould. The leaching of tritium from waste solidified/encapsulated in the cement mixtures immersed in an aqueous environment has been studied in order to select the most appropriate grout type as waste immobilization matrix.Samples from the liquid surrounding the cements blocks were collected at predetermined time intervals and placed in the liquid scintillation cocktail and measured. The activity of the tritium released was then calculated.

Tritium Modeling for ITER Test Blanket Module

HCPB (Helium Cooled Pebbles Bed) Test Blanket Model (TBM) is based on solid breeder. Tritium has to be extracted using Helium purge gas flowing through breeder pebbles bed. He-stream must be cooled down and processed and all these steps are carried out in TES (Tritium Extraction System). A modeling work has been performed to study the behavior of the TES of the HCPB TBM and for Molecular Sieve 5A as adsorbent material. The result is the capability to model the extraction process of gaseous tritium compounds and to estimate the breakthrough curves of two main tritium gaseous species (H2 and HT).

Tritium control in fusion reactor materials: A model for Tritium Extracting System

In fusion reactors, tritium is bred by lithium isotopes inside the blanket and then extracted. However, tritium can contaminate the reactor structures, and can be eventually released into the environment. Tritium in reactor components should therefore be kept under close control throughout the fusion reactor lifetime, bearing in mind the risk of accidents, the need for maintenance and the detritiation of dismantled reactor components before their re-use or disposal. A modeling work has been performed to address these issues in view of its utilization for the TES (Tritium Extraction System), in the case of the HCPB TBM and for a molecular sieve as adsorbent material. A computational model has been setup and tested. The results of experimental measurement of fundamental parameters such as mass transfer coefficients have been implemented in the model. It turns out the capability of the model to describe the extraction process of gaseous tritium compounds and to estimate the breakthrough curves of the two main tritium gaseous species (H2 and HT).

The case for fractional solubility profiles

Default values for the solubility of various compounds in the lung are provided in publications of the International Commission on Radiological Protection as absorption types to characterizes the potential uptake of radionuclides to blood. The default assignments are conservative and reflect compounds likely to be encountered in the workplace. In practice, solubility profiles for many compounds, both natural and man-made, are complex, with a fraction of the compound in each absorption type, denoted as F, M, or S. Only soluble compounds of tritium and iodine can be reasonably assumed to be of one absorption type. The assumption of a single absorption type for airborne distributions of solid particulate matter can introduce order of magnitude errors in internal dosimetry calculations. The problem is particularly acute for isotopes with dual toxicity (e.g. uranium which is both nephrotoxic and radiotoxic), and when a dose estimate must be derived with only a single bioassay measurement. For inhalation exposures during an accident, treatment decisions frequently must be made quickly to be effective. While much work has been done to develop rapid bioassay methods that will provide data in a clinically useable timeframe, little consideration has been given to the magnitude of the error in the dose estimate resulting from the assumption of the default solubility profiles.

DISSOLUTION RATE AND BIOKINETIC MODEL OF ZIRCONIUM TRITIDE PARTICLES IN RAT LUNGS

Metal tritide has been used for different areas such as research, purification, compression, and storage of tritium. Current radiation protection guidelines for tritium compounds describe the behavior of the metal tritide as the same as that of organically bound tritium. However, the biokinetic behavior of metal tritide varies according to materials. This study evaluated the behavior of zirconium tritide (ZrT) particles in rat lungs. The dissolution rate of the ZrT particles in simulated lung fluid was obtained from a specific setup. The ZrT was classified as type-S material according to its low dissolution rate. The ZrT particles were then instilled into rat lungs. The tritium retention time in different rat organs and tritium clearance from rats was obtained by sacrificing a total of 44 rats in a 6 mo period. A biokinetic model for ZrT particles in rat lungs was developed. The predicted retention curves with various phases of tritium in each organ agreed very well with the experimental data. The result can be used to estimate the human annual limit of intake and derived air concentration of ZrT particles.

Radiation doses from some [3H]-labelled organic compounds following ingestion

Published information, especially human data, on the biokinetics of 11 compounds labelled with 3H was used to develop simple, cautious compound-specific models and to calculate both tissue absorbed doses and effective doses using the OLINDA computer code. The compounds were [3H]-cortisol, 3alpha-Hydroxy-5beta-pregnane-11, 20-dione-7-[3H], cyclic 20 trimethylene acetal, [3H]-ifetroban, [3H]-digoxin, 7-[2'-alpha-methylphenylethylamino[3H]]theophylline, 7-[2'-alpha-methylphenylethylamino]theophylline-[3H], [3H]-amphetamine, [17(3)H]-nicergoline, [3H]-colestipol, [3H]-5(S)-benzamido-4-oxo-6-phenylhexanoyl-l-proline and [6-(3)H]-thymidine. The calculated effective doses ranged from 6 to 87% of that predicted by the ICRP default model for uncharacterised organic compounds of tritium (OBTM). For all the compounds studied, the retention of 3H in the body was less than that predicted by the OBTM and the route of excretion was found to influence both tissue and effective doses. It is concluded that although the ICRP OBT model may underestimate doses for specific compounds by up to an order of magnitude, it can still be applied with caution for prospective radiological protection purposes, but it should not be applied for the interpretation of bioassay data.

Low level cleaning of a fusion target chamber

Fusion experiments involving a deuterium–tritium compound can be considered in the near future at CEA/DAM/Cesta using the laser integration line facility (LIL; prototype of the laser mega joule (LMJ), under construction). Nevertheless, non-contaminated materials are currently favoured in order to minimise exploitation constraints. Hence, as it presented low but significant levels of contamination (tritium and beryllium), the LIL target chamber was cleaned up before being installed. A comparison of selected decontamination methods has been made based on their ability to reach very low levels of contamination (i.e. the lowest contamination threshold in transportation regulations and beryllium public limit), their efficiency and compatibility with vacuum objectives. The process was thereby performed at CEA/DAM/Cesta in 2001, using an acid foam technique in a dedicated installation. Its implementation and effectiveness are further discussed in this paper.

Application of the ICRP clarification of the tritium metabolic model.

In 2001, the International Commission on Radiological Protection published a clarification to the model for tritium metabolism. This clarification described the use of the gastrointestinal tract model, respiratory tract model, and transfer compartment in calculations of tritium metabolism. This information was used to derive intake retention fractions for tritium and tritium compounds including tritiated water, organically bound tritium, and tritides. In addition, dose coefficients were derived for tritide compounds including general categories described by the ICRP and some specific compounds.

Separation of Tritium Compounds Using Porous VYCOR Glass Tube Wall

ABSTRACTTritium compounds need to be separated to each chemical form for reasonable and continuous monitoring of tritium compounds. In this study, the continuous monitoring of HT in the air containing HT and HTO was investigated using the separation cell made of porous Vycor glass tube. The apparatus for a continuous and selective monitoring of tritium compounds in the air containing HT and HTO was constructed of radioactive gas monitor, ion chamber and the separation cell. An air containing tritium compounds (HT, HTO, etc.) was provided by Research Reactor Institute of Kyoto University. In the air containing of HT and HTO, HT is found to permeate selectively through the pores of the porous Vycor glass tube wall.