Tritium Radiation Research Articles

Measurement Techniques for Low-Concentration Tritium Radiation in Water: Review and Prospects.

Tritium (3H) is one of the most critical nuclides for environmental monitoring, yet it is challenging to measure. Its high natural mobility and its potential to enter the human body through the food chain underscore the importance of not overlooking the radiation safety risks associated with tritium. The need for the online measurement of tritium at low concentrations is becoming increasingly apparent. This review examines the two principal stages of current measurement methodologies: sample preparation and radiation signal detection. It provides a summary of the tritium sample preparation and detection techniques, highlighting advances in the research with potential applications in online monitoring. The review concludes with an analysis of the issues inherent in the current techniques and offers perspectives on possible technological enhancements and future trajectories for the development of online monitoring systems for trace tritium levels.

Теоретический анализ качества излучения и относительной биологической эффективности трития

Introduction 1. Tritium and reference radiation 1.1 Tritium isotope and its energy spectrum 1.2 Reference radiation 2. Methods for determining the quality of radiation and RBE 2.1 Radiation quality in microdosimetry 2.2 RBE by the number of DNA double-strand breaks 2.3 RBE by fraction of secondary low-energy electrons 3. Analysis of calculations of radiation quality and tritium RBE 3.1 Estimation of tritium emission quality factors 3.2 Evaluation of the RBE of tritium radiation during its action on DNA 3.3 Estimation of the RBE of tritium from the fraction of secondary low-energy electrons 3.4 Quality factors and RBE of tritium with respect to reference emissions Conclusion

Assessing OBT formation and enrichment: ROS signaling is involved in the radiation hormesis induced by tritium exposure in algae.

Tritium is the main component of radioactive wastewater from nuclear power plants and can be migrated into organisms to form organically bound tritium (OBT), which may pose a potential risk to aquatic ecosystem. Hence, it is essential to monitor OBT conversion in the presence of tritium exposure. In this study, the effects of pretreatment methods such as digestion on the recovery of tritium were discussed. It was found that microwave digestion pretreatment could improve the recovery of tritium by up to 90 % and allow OBT measurement with a small sample size equivalent to about 60mg (dry weight). In addition, the efficiency of OBT transformation was different among biological samples, and the radiation hormesis phenomenon was induced by tritium exposure (3.7× 106 Bq/L) in microalgae Chlorella vulgaris（C. vulgaris）. The tritium exposure may induce radiation hormesis through the reactive oxygen species (ROS) signaling pathway, thus improving the photosynthetic capacity and metabolism level of C. vulgaris. Furthermore, enhancement of photorespiration metabolism and the antioxidation system may be important means for C. vulgaris to balance damage by tritium radiation. This study provides insights for further investigating OBT behavior, and will contribute to understanding the equilibrium damage mechanism of algae exposed to tritium.

Microfluidic preparation of monodisperse hollow polyacrylonitrile microspheres for ICF

Hollow polyacrylonitrile (PAN) microspheres can be used as fuel carriers in inertial confinement fusion (ICF) experiments due to their high tensile strength, low permeability to hydrogen isotopes, and resistance to tritium radiation corrosion. Monodisperse oil in water in oil (O1/W/O2) compound droplets were fabricated by the microfluidic technique and then monodisperse hollow polyacrylonitrile microspheres were prepared by the solvent evaporation method. The stability of O1/W/O2 compound droplets was improved by the addition of the surfactant (Dow Corning 749), which reduced the interfacial tension between the O2 phase and the W phase as well as the Laplace pressure on the surface of the compound droplets. The sphericity and the surface quality of the microspheres were also improved by the introduction of DMF droplets into the O2 phase to avoid emulsification, decreasing the DMF mass transfer rate. Therefore, fine monodisperse PAN microspheres with the diameter range of 700–800 µm were successfully prepared. Moreover, the size relationship between the compound droplets and the resulting microspheres was also evaluated, which can be used to predict the sizes of the PAN microspheres. The results provide a method for controllable preparation of monodisperse hollow PAN microspheres for ICF experiments.

Enzymatic Responses to Low-Intensity Radiation of Tritium.

The present study considers a possible role of enzymatic reactions in the adaptive response of cells to the beta-emitting radionuclide tritium under conditions of low-dose exposures. Effects of tritiated water (HTO) on the reactions of bacterial luciferase and NAD(P)H:FMN-oxidoreductase, as well as a coupled system of these two reactions, were studied at radioactivity concentrations ≤ 200 MBq/L. Additionally, one of the simplest enzymatic reactions, photobiochemical proton transfer in Coelenteramide-containing Fluorescent Protein (CLM-FP), was also investigated. We found that HTO increased the activity of NAD(P)H:FMN-oxidoreductase at the initial stage of its reaction (by up to 230%); however, a rise of luciferase activity was moderate (<20%). The CLM-FP samples did not show any increase in the rate of the photobiochemical proton transfer under the exposure to HTO. The responses of the enzyme systems were compared to the ‘hormetic’ response of luminous marine bacterial cells studied earlier. We conclude that (1) the oxidoreductase reaction contributes significantly to the activation of the coupled enzyme system and bacterial cells by tritium, and (2) an increase in the organization level of biological systems promotes the hormesis phenomenon.

Monitoring of Tritium Internal Exposure Doses of Heavy-Water Reactor Workers in Third Qinshan Nuclear Power Plant

To analyze the tritium internal exposure dose of workers in the Third Qinshan Nuclear Power Plant over the past 15 years. Urine samples provided by workers are tested directly to analyze the tritium concentrations and estimate internal exposure dose. Since 2004, an average of approximately 1600 workers have been monitored annually, with an average annual monitoring frequency of approximately 11 000. Since 2004, the average annual collective dose of tritium internal exposure was 149.62 person·mSv, accounting for 19.07% of the total annual collective dose. A total of 18 workers’ annual individual internal tritium radiation doses exceeded 2 mSv, of which 5 workers’ internal tritium radiation doses in a single intake exceeded 2 mSv. The occupational population with the largest total internal tritium radiation doses consists of maintenance personnel, fuel operators, and radiation protection personnel, whose collective doses of internal exposure account for 75.51% of the total collective doses within the plant. Over 15 years of operation, the internal tritium radiation doses of workers in the Third Qinshan Nuclear Power Plant have been strictly controlled within the national regulatory limit and power plant management target, ensuring the health and safety of the workers.

Reactive Oxygen Species and low-dose effects of tritium on bacterial cells

The paper continues study of exposures of luminous marine bacteria to low-dose radiation of tritium; tritiated water (HTO) was applied as a source of the irradiation. Hypothesis on involvement of Reactive Oxygen Species (ROS) to signaling mechanism of bacterial cells under exposure to low-intensity tritium radiation was verified. Bacterial bioluminescence intensity was considered as a tested physiological parameter; it was compared to the ROS production in the bacterial environment of different activity concentrations: 0.03, 4.0, and 500 MBq/L. Exposure of the bacteria to chronic low-dose tritium irradiation (<0.08 Gy) increased bioluminescence intensity and ROS production considerably (up to 300%). Spearman rank correlation coefficients were calculated and confirmed relations between the bioluminescence intensity and ROS production. Additional peculiarities of HTO effect were: independence of the bioluminescence intensity and ROS content on HTO activity concentration; low ROS content in bacteria-free aquatic environment. Effects of HTO on bacterial bioluminescence were attributed to: (1) trigger function of tritium decay products in the bacterial metabolic oxygen-dependent processes, with bioluminescence involved; (2) signaling role of ROS as intercellular messengers in “bystander effect”; (3) fixed amount of bacterial cells (3•107 cells/mL) provided the upper limits of the bioluminescence intensity and ROS content. As an outlook, in spite of low energy of tritium decay, its influence on aquatic biota via ROS production by microorganisms should be taken into consideration.

Antibody-Free Assay for RNA Methyltransferase Activity Analysis.

There are more than 100 chemically distinct modifications of RNA, two thirds of which consist of methylations. Interest in RNA modifications, and especially methylations, has re-emerged due to the important roles played by the enzymes that write and erase them in biological processes relevant to disease and cancer. Here, a sensitive in vitro assay for accurate analysis of RNA methylation writer activity on synthetic or in vitro transcribed RNAs is provided. This assay uses a tritiated form of S-adenosyl-methionine, resulting in direct labeling of methylated RNA with tritium. The low energy of tritium radiation makes the method safe, and pre-existing methods of tritium signal amplification, make it possible to quantify and to visualize the methylated RNA without the use of antibodies, which are commonly prone to artifacts. While this method is written for RNA methylation, few tweaks make it applicable to the study of other RNA modifications that can be radioactively labeled, such as RNA acetylation with 14C acetyl coenzyme A. Overall, this assay allows to quickly assess RNA methylation conditions, inhibition with small molecule inhibitors, or the effect of RNA or enzyme mutants, and provides a powerful tool to validate and expand results obtained in cells.

3-dimensional eksternal electric field effect (Stark effect) on the ground state energy of Tritium atom

Tritium Atom is a Radioisotope that has a half-life of 12.3 years. This atom produces beta decay with a maximum generated energy of 18.598 KeV and an average energy of 5.7 KeV. Tritium radiation is still relatively safe, so it is widely used in the field of electronics especially in the development of betavoltaics batteries. This research will delve into the effect of 3-dimensional external electric field on Tritium energy on the ground state. The method applied in this research is Rayleigh-Schrodinger Perturbation Theory, which also encompasses second order correction. In addition, by reviewing the movement of electrons fast enough to surround the nucleus, then the relativistic effect will also exert effect to the energy of Tritium atoms. The 3-dimensional electric field effect (in the x, y and z axis) will give different energy shifts with the 1-dimensional perturbation effect. This shift of energy will have an impact on the binding energy of nucleus and electron. The results of mathematical calculations have proven that a significant shift in energy only occurs in a strong external electric field, approximately higher than 1 × 1011 V/m.

Tritium biology in Japan: A search for a new approach

The health effects of tritium are a major public concern in Japan due to the presence of tritium (HTO) contaminated water at the Fukushima Dai-ichi Nuclear Power Plant (Fukushima NPP). From a scientific view, the biological effects of the contaminant HTO at the Fukushima NPP could conceivably be quite small, but the possibility of stochastic effects from tritium radiation cannot be neglected. This reasoning is based on the linear no-threshold (LNT) model, which is cited in ICRP recommendations and suggests an elevation in the frequency of the stochastic effects of radiation, even when the doses are less than 100 mGy. However, at the present, only a small amount of experimental data is available describing the biological effects of low doses radiation, and there are no established experimental systems that can clearly show whether or not the LNT model is appropriate. This is due to a wide scatter in data for the incidence of stochastic effects, which makes it difficult to distinguish radiation-induced events from spontaneous events. We propose overcoming this difficulty for radiobiology experiments using low doses or low dose rate radiation by establishing hypersensitive assay systems, and report on the current status of work investigating tritium radiobiology in Japan.

Fluorescent coelenteramide-containing protein as a color bioindicator for low-dose radiation effects

The study addresses the application of fluorescent coelenteramide-containing proteins as color bioindicators for radiotoxicity evaluation. Biological effects of chronic low-dose radiation are under investigation. Tritiated water (200MBq/L) was used as a model source of low-intensive ionizing radiation of beta type. 'Discharged obelin,' product of bioluminescent reaction of marine coelenterate Obelia longissimi, was used as a representative of the coelenteramide-containing proteins. Coelenteramide, fluorophore of discharged obelin, is a photochemically active molecule; it produces fluorescence forms of different color. Contributions of 'violet' and 'blue-green' forms to the visible fluorescence serve as tested parameters. The contributions depend on the coelenteramide's microenvironment in the protein, and, hence, evaluate distractive ability and toxicity of radiation. The protein samples were exposed to beta radiation for 18days, and maximal dose accumulated by the samples was 0.28Gy, being close to a tentative limit of a low-dose interval. Increase of relative contribution of 'violet' fluorescence under exposure to the beta irradiation was revealed. High sensitivity of the protein-based test system to low-dose ionizing radiation (to 0.03Gy) was demonstrated. The study develops physicochemical understanding of radiotoxic effects. Graphical abstract Coelenteramide-containing protein (discharged obelin) changes fluorescence color under exposure to low-dose ionizing radiation of tritium.

Gas-filled radioluminescent light sources and prospects for their further development

Luminescence of various inorganic compounds of rare earth elements as radioluminophores was studied with the aim of fabricating weak permanent light sources. Under the action of UV and tritium radiation, all the luminophores tested emit light of different colors. In the tritium gas medium, six luminophores showed emission, and for three of them (Y2O3:Eu, Y2O3:Eu, Bi, Gd2O3:Eu) the emission brightness was acceptable for practical use. Attempt to prepare permanent light sources with new types of luminophores using a phosphoric acid solution as a binder demonstrated the need for searching for a new binder firmly fixing the luminophore on the glass surface.

Human circulating plasma DNA significantly decreases while lymphocyte DNA damage increases under chronic occupational exposure to low-dose gamma-neutron and tritium β-radiation

The blood plasma of healthy people contains cell-fee (circulating) DNA (cfDNA). Apoptotic cells are the main source of the cfDNA. The cfDNA concentration increases in case of the organism’s cell death rate increase, for example in case of exposure to high-dose ionizing radiation (IR).The objects of the present research are the blood plasma and blood lymphocytes of people, who contacted occupationally with the sources of external gamma/neutron radiation or internal β-radiation of tritium N=176). As the controls (references), blood samples of people, who had never been occupationally subjected to the IR sources, were used (N=109). With respect to the plasma samples of each donor there were defined: the cfDNA concentration (the cfDNA index), DNase1 activity (the DNase1 index) and titre of antibodies to DNA (the Ab DNA index). The general DNA damage in the cells was defined (using the Comet assay, the tail moment (TM) index).A chronic effect of the low-dose ionizing radiation on a human being is accompanied by the enhancement of the DNA damage in lymphocytes along with a considerable cfDNA content reduction, while the DNase1 content and concentration of antibodies to DNA (Ab DNA) increase. All the aforementioned changes were also observed in people, who had not worked with the IR sources for more than a year. The ratio cfDNA/(DNase1×Ab DNA×TM) is proposed to be used as a marker of the chronic exposure of a person to the external low-dose IR. It was formulated the assumption that the joint analysis of the cfDNA, DNase1, Ab DNA and TM values may provide the information about the human organism’s cell resistivity to chronic exposure to the low-dose IR and about the development of the adaptive response in the organism that is aimed, firstly, at the effective cfDNA elimination from the blood circulation, and, secondly – at survival of the cells, including the cells with the damaged DNA.

Hydrogen Isotope Equilibration Induced by Tritium Radiation - Ab Initio Approach to Reaction Kinetics

Radiation-induced isotopic equilibration in hydrogen gas containing tritium has to be accounted for when cryogenic distillation of hydrogen isotopes is used for their separation. In the absence of sufficient experimental data on the reaction kinetics an appropriate theoretical model is proposed. Unknown parameters of the model have been estimated with use of Möller-Plesset ab initio method. The results of calculations are in a reasonable agreement with certain experiments performed earlier by other authors. The dependencies of equilibration rate on temperature, pressure, and tritium molar fraction are established for isotope mixtures containing no impurities.

Assessment of Biological Effect of Tritiated Water by Using Hypersensitive System

An exposure of human or animals to tritium radiation from nuclear fusion reactor is expected to be a low dose and with low dose-rate. We are focusing on the biological effects of tritiated water (HTO) given at low dose and/or with low dose rate. Hypersensitive assay systems for radiation biological experiments using cultured mammalian cells or transgenic mice have been established and their availability for assessment of biological effects of HTO were tested. A hypersensitive detection system for mutagenesis at Hprt locus was established by using hamster cells carrying a human X-chromosome. The cells present more than 50-fold sensitivity for Hprt-deficient mutation, and this allowed us to detect a significant elevation of mutation frequency by radiations at the dose of less than 0.2 Gy.Because the reverse dose rate effect has been reported for mutation induction by high LET radiation such as neutrons, we first tested whether the reverse dose rate effects could be seen for HTO (tritium beta-rays) or not. No significant change in mutation frequency by HTO was observed in the range of dose rates between 0.05 cGy/h and 2.0 cGy/h, whereas clear reverse dose rate effects was observed in the case of fission neutrons or carbon beam. The result suggests that the reverse dose rate effect does not apply in the case of mutation induction by HTO. In addition, mutation spectrum in the mutants induced by HTO was similar to those in spontaneously induced mutants, suggesting that exposure to a certain level of HTO could enhance the spontaneous mutagenesis.

Three-dimensional nuclear analysis for the US dual coolant lead lithium ITER test blanket module

Detailed 3-D neutronics calculations have been performed for the US DCLL TBM. The neutronics calculations were performed directly in the CAD model using the DAG-MCNP code that allows preserving the geometrical details. Detailed high-resolution, high-fidelity profiles of the nuclear parameters were generated using fine mesh tallies. These included tritium production, nuclear heating, and radiation damage. The TBM heterogeneity, exact source profile, and inclusion of the surrounding frame and other in-vessel components result in lower TBM nuclear parameters compared to the previous 1-D predictions. This work clearly demonstrates the importance of preserving geometrical details in nuclear analyses of geometrically complex components in fusion systems.

A Method of Calibration for Measurement of Low Level Tritium in Environmental Water using a Liquid Scintillation Counter

When low levels of tritium are measured in water, quantifying and removing the background reading caused by other influences is very important. A liquid scintillation counter (LSC) and tritium-free water are most commonly used for measuring tritium and estimating the background caused by various sources. Tritium-free water is difficult to obtain and maintain, and developing a method for estimating the background without using tritium-free water is an important contribution. This study establishes such a method using a tritium enrichment operation on tritiated water samples which have several concentration levels. Because the value measured by the LSC is composed of the tritium signal and the background, an enrichment operation will only increase the tritium radiation signal. On this premise, tritiated water samples with several levels of tritium activity were enriched and used to quantify the background statistically.

Tritium Test of a Ferrofluidic Rotary Seal

The ferrofluidic seal is being investigated as an internal rotary seal for tritium compatible mechanical roots type vacuum pumps. After its successful testing with helium and integration into a small (250 m3/h) test roots pump, the seal, made as a cartridge, has been integrated into a special test unit and is currently being tested with tritium in order to define the leak rates and the possible degradation of the ferrofluid under long term exposure to tritium radiation. The tritium pressure from one side of the seal is 0.125 MPa, the nitrogen pressure from the other side is 0.075 MPa, the rotation speed is maintained at 1500 rpm. The tritium leak through the cartridge contributes to the tritium concentration in the nitrogen, which is continuously measured by an ionisation chamber; the pressure in both chambers is continuously registered by precise pressure gauges. The experimental program is discussed.

Biologically Based Analysis of Lung Cancer Incidence in a Large Canadian Occupational Cohort with Low-Dose Ionizing Radiation Exposure, and Comparison with Japanese Atomic Bomb Survivors

Lung cancer incidence is analyzed in a large Canadian National Dose Registry (CNDR) cohort with individual annual dosimetry for low-dose occupational exposure to gamma and tritium radiation using the two-stage clonal expansion model (TSCE) and extensions of the model with up to 10 initiation steps. Models with clonal expansion turned off provide very poor fits and are rejected. Characteristic and distinct temporal patterns of excess relative risk (ERR) are found for dose response affecting early, middle, or late stages of carcinogenesis, that is, initiation with one or more stages, clonal expansion, or malignant conversion. Both fixed lag and lag distributions are used to model time from first malignant cell to incidence. Background rates are adjusted for gender and birth cohort. Lacking individual smoking data, surrogate annual smoking doses based on U.S. annual per capita cigarette consumption appear to account for much of the birth cohort effect, leaving radiation dose response relatively unchanged. The mean cumulative exposure for males receiving nonzero cumulative doses of gamma and tritium radiation was 18.2 mSv. The males have a significant dose response with 33 out of a total of 322 lung cancer cases attributable to radiation. There were 78 incident lung cancer among females, (with mean cumulative exposure of 3.8 mSv among females with nonzero exposure). The dose response for females appears smaller than for males but does not differ significantly from zero or from the male dose response. Findings for males include significant dose-response relationships for promotion and malignant conversion, but not initiation, and a protraction effect (sometimes called an inverse-dose-rate effect, where risk increases with protraction of a given dose). The dose response predicted by our analysis appears consistent with the risk for lung cancer incidence in the Japanese atomic bomb survivors cohort, provided that proper adjustments are made for duration of exposure and differences in background rate parameters. We acknowledge support from the Department of Energy (DOE) under grant DE-FG02-03ER63675, and from the Center for Disease Control (CDC) under grant R01 0H07864. This report makes use of data obtained from the Radiation Effects Research Foundation (RERF) in Hiroshima, Japan. RERF is a private foundation funded equally by the Japanese Ministry of Health and Welfare and the U.S. Department of Energy through the U.S. National Academy of Sciences. The conclusions in this report are those of the authors and do not necessarily reflect the scientific judgment of RERF or its funding agencies.

Analysis of mutation induction by low dose rate tritium radiation using a hyper- sensitive system

Analysis of mutation induction by low dose rate tritium radiation using a hyper- sensitive system