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Tritium extraction from radioactively contaminated cement mortar samples was performed using heating and liquid scintillation counting methods. Tritiated water molecules (HTO) can be present in contaminated water along with water molecules (H2O). Water is one of the primary constituents of cement mortar dough. Therefore, if tritium is present in cement mortar, the buildings and structures using this cement mortar would be contaminated by tritium. The radioactivity level of the materials in the environment exposed to tritium contamination should be determined for their disposal in accordance with the criteria of low-level radioactive waste disposal facility. For our experiments, the cement mortar samples were heated at different temperature conditions using a high-temperature combustion furnace, and the extracted tritium was collected into a 0.1 M nitric acid solution, which was then mixed with a liquid scintillator to be analyzed in a liquid scintillation counter (LSC). The tritium extraction rate from the cement mortar sample was calculated to be 90.91% and 98.54% corresponding to 9 h of heating at temperatures of 200 °C and 400 °C, respectively. The tritium extraction rate was close to 100% at 400 °C, although the bulk of cement mortar sample was contaminated by tritium.

Distribution of tritium between vapor and lithium chloride aqueous solutions at 30–80 °C has been studied with the aid of vacuum distillation technique. “Positive” H/T VPIE (separation ratio increases with solute concentration) was observed. This ratio depends linearly on the salt molality and decreases with temperature. The results are in agreement with theoretical estimates of “free” water – hydrate shell H/T isotope equilibrium constants done with DFT force field calculations and harmonic oscillator quantum statistics. Found growth of the separation ratio may be practically important for developing extractive distillation process to remove tritium from technological solutions and liquid wastes of nuclear industry.

Developing an online monitoring system becomes useful for continuously detection of tritium in water. A plastic scintillator chamber was used to tritium detection in hydrogen gas produced by a proton exchange membrane electrolysis cell. The fractionation factor (proton selectivity) was estimated as being of 5.41 ± 0.20, and detection efficiency of the plastic scintillator chamber was 4.25 ± 0.22%. For liquid samples, the minimum detectable activity of the developed system was estimated as 655 kBq L−1. Using this online technique for tritium monitoring based on electrolysis is expected to be useful for analysis of large tritiated water bearing samples.

The electrolysis conditions in a proton exchange membrane (PEM) cell were optimized by varying the current supplied; the detection efficiency for gaseous tritium generated from the PEM cell under optimized electrolysis conditions was analyzed. The current was optimized to 7 A. Under the optimized current condition, the change in activity of the tritiated water before and after electrolysis was 200 ± 11 kBq. When tritiated water with tritium activity concentration of 2912 kBq/L was electrolyzed, the detection efficiency was 31.3 ± 1.3%. Moreover, the minimum detectable activity of gaseous tritium was 10.3 ± 0.8 kBq/m3 in 5 min.

Detection and measurement of low-energy beta particles is commonly achieved by liquid scintillation counting, in particular for low-level tritium samples. When samples are contained in plastic scintillation vials for long-term storage, the tritium activity in the vials has been found to decrease faster than expected from its natural radioactive decay. Different explanations for this observation have attributed some of these tritium activity losses to diffusion of the sample, degradation of the LSC cocktail, and the potential long-term changes in quenching effects of the LSC cocktail. An alternative explanation may also be that the tritium organically binds to the carbon chains in the plastic bottle through direct H and H atom exchange. A study was designed and performed to test this latter hypothesis of H and H atom exchange in plastic. Deionized water was introduced in a plastic vial that previously contained tritiated water to assess any increase in tritium activity from the reverse atom exchange between the vial material and the deionized water. A greater loss in activity concentration is observed in plastic vials compared to glass vials as a function of storage time for the tritiated water. Furthermore, the tritium activity concentration in the deionized water increased when storage occurred in plastic vials, an effect that is not observed for storage in glass vials. The study results indicate that hydrogen atom exchange may possibly take place in plastic vials.

A comparison of the activity concentration measurement of a 3H2O solution was organized by the LNE-LNHB under the auspices of the CCRI(II). The solution was sent to thirteen laboratories and eleven measurement reports were received. The results, as well as relevant information on the measurement techniques, are presented and analysed in this paper. All results are consistent within uncertainties. As the solution was traceable to the solution used in the CCRI(II)-K2.H-3 comparison in 2009, the results of both comparisons are also presented. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

The health hazard of tritium is related to its chemical form. Sampling different chemical forms of tritium simultaneously becomes significant. Here a novel atmospheric tritium sampling system (TS-212) was developed to collect the tritiated water (HTO), tritiated hydrogen (HT) and tritiated methane (CH 3 T) simultaneously. It consisted of an air inlet system, three parallel connected sampling channels, a hydrogen supply module, a methane supply module and a remote control system. It worked at air flow rate of 1 L/min to 5 L/min, with temperature of catalyst furnace at 200 °C for HT sampling and 400 °C for CH 3 T sampling. Conversion rates of both HT and CH 3 T to HTO were larger than 99%. The collecting efficiency of the two-stage trap sets for HTO was larger than 96% in 12 h working-time without being blocked. Therefore, the collected efficiencies of TS-212 are larger than 95% for tritium with different chemical forms in environment. Besides, the remote control system made sampling more intelligent, reducing the operator’s work intensity. Based on the performance parameters described above, the TS-212 can be used to sample atmospheric tritium in different chemical forms.

A new apparatus for measuring tritiated water in expired air was developed using plastic scintillator (PS) pellets and a low-background liquid scintillation counter. The sensitivity of the apparatus was sufficient when a large adapted Teflon vial was used. The measurement method generated low amounts of organic waste because the PS pellets were reusable by rinsing, and had adequate detection limits. The apparatus is useful for the safety management of workers that are exposed to radioactive materials.

Double strand breaks (DSBs) of DNA molecules in tritiated water was examined under sterilized and non-sterilized conditions using a single molecule observation method. The genome DNA of bacteriophage T4 GT7 was immersed in sterilized tritiated water (5.2 MBq/cm3) and non-sterilized tritiated water (4.2 MBq/cm3) for 1, 7 and 14 day(s). Then the length of DNA molecules was measured using a fluorescence microscope after intercalation of fluorescent dye. The dose rate was 1.4–1.7 × 10−2 Gy/h and the dose level was 0.41–5.8 Gy. The rate of DSBs induced by β-rays from tritium was successfully evaluated under the sterilized conditions and the value comparable with the DSB rate under γ-ray irradiation (Noda et al., Scientific Reports 7 (2017) 8557) was obtained. The length of DNA molecules in non-sterilized tritiated water was clearly shorter than that in the sterilized tritiated water. This observation suggested that the effects of tritium was far weaker than that of microorganisms (e.g. bacteria) and impurities in water even at the tritium concentration as high as 5.2 MBq/cm3.

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.

The luminescence of Eu(DPA)33- induced by beta particles from tritium decay was measured. The solution of Eu3+ was prepared with europium(III) nitrate hexahydrate and was mixed with a DPA (2, 6-pyridinedicarboxylic acid or dipicolinic acid) solution of pH 11 to yield Eu(DPA)33-. The formation of Eu(DPA)33- was confirmed through spectrometry. Tritiated water was added to the prepared solution of Eu(DPA)33-. The luminescence intensity is proportional to the amount of tritium. In this paper we demonstrate the potential of this Eu complex as an inorganic liquid scintillator.

Nuclear fusion technology is expected to create new energy in the future. However, nuclear fusion requires a large amount of tritium as a fuel, leading to concern about the exposure of radiation workers to tritium beta radiation. Furthermore, countermeasures for tritium-polluted water produced in decommissioning of the reactor at Fukushima Daiichi Nuclear Power Station may potentially cause health problems in radiation workers. Although, internal exposure to tritium at a low dose/low dose rate can be assumed, biological effect of tritium exposure is not negligible, because tritiated water (HTO) intake to the body via the mouth/inhalation/skin would lead to homogeneous distribution throughout the whole body. Furthermore, organically-bound tritium (OBT) stays in the body as parts of the molecules that comprise living organisms resulting in long-term exposure, and the chemical form of tritium should be considered. To evaluate the biological effect of tritium, the effect should be compared with that of other radiation types. Many studies have examined the relative biological effectiveness (RBE) of tritium. Hence, we report the RBE, which was obtained with radiation carcinogenesis classified as a stochastic effect, and serves as a reference for cancer risk. We also introduce the outline of the tritium experiment and the principle of a recently developed animal experimental system using transgenic mouse to detect the biological influence of radiation exposure at a low dose/low dose rate.

Tritium is one of the factors of internal exposure of the humans both in occupational and public environments. It enters the body mainly as tritiated water through inhalation, with food, drinks and through the skin; part of tritium gradually transforms into the metabolised organically bound tritium as a result of biochemical reactions. The purpose of this study was to evaluate organically bound tritium contribution to the effective dose of an adult using the biokinetic model and real dosimetric data. The data of long term monitoring from 6 studies with 17 workers or volunteers following single intake of tritiated water in the body were selected from 9 publications (1968-1997). Three two-compartment models of tritium biokinetics were used in this study: recurrent model with gradual transformation of tritium from tritiated water into organically bound tritium and tritiated water excretion; model with instant transformation of tritium into organically bound tritium and tritiated water excretion; model with instant transformation of tritium into organically bound tritium and both tritiated water and organically bound tritium excretion (according to ICRP). The ICRP model doesn’t properly reflect the real tritiated water metabolism in the human body: second exponent of the tritiated water content in the body water and accumulation of the organically bound tritium fraction are absent. The organically bound tritium fraction composes 3% of tritiated water in ICRP model. It is significantly higher compared to two other models (0,4% and 0,8%). According to the first model the contribution of OBT fraction to the mean dose varied from 1,8 to 4,6% for individuals; mean value was 3,0 ± 0,9%. According to the second model the contribution of organically bound tritium fraction was slightly higher: 3,6 ± 1,1%, according to the ICRP model – 9%. The dynamic of excretion of tritium with urine can be described with double-exponential curves and provides the basis for two-compartment modeling. The recurrent model with tritiated water excretion was more adjusted to human physiology. Contribution of organically bound tritium to effective dose can be somewhat higher than that to absorbed dose defined in this work. The presented dose assessment system can be used when specified individual absorbed dose reconstruction in tissues is necessary following accidental intake of large tritium activities.

As radioactive wastes, contaminated vacuum pump oils from tritium-processing facilities are challenging to dispose of. In this study, we investigated the mechanism of the tritium–hydrogen (T–H) exchange reaction between the tritiated water (HTO) and many typical organic molecules in vacuum pump oil using a density functional theory (DFT) method. The T–H exchange reaction could proceed with two mechanisms, the direct T–H exchange mechanism and the addition–elimination T–H exchange mechanism. The calculation indicates that the direct T–H exchange mechanism is kinetically favored. The HTO molecule is not only a reactant, but also acts as the proton shuttle in the transition state. The number of HTO molecules participating in the reaction is determined by the formation of the stable six-membered ring proton migration transition state. The T–H exchange reaction is selective, and molecules with COOH and OH groups preferentially undergo hydrogen exchange with HTO. In the case of multiple possible products, the calculations correctly predicted the predominant product. The results here will provide guidance for improving the associated decontamination process and reducing the environmental impact.

A powerful neutron source, the European Spallation Source (ESS), is currently under construction in Lund, Sweden (~90 000 inhabitants). Levels of tritium (3H) in urine were estimated in members of the public in Lund and employees at the ESS using liquid scintillation counting, to obtain baseline levels before the start of operation of the ESS. These were compared with levels in other occupationally exposed radiation workers. Both the spallation reaction in the ESS tungsten target and the activation of various materials by the protons produced by the 5 MW linear accelerator will generate tritium, which will be released into the atmosphere mainly as tritiated water (HTO). Urinary HTO activity concentrations were determined in a total of 55 individuals belonging to four different categories: ESS employees, neighbours of the ESS, members of the general public in Lund and exposed workers from other facilities. The participants were asked to provide information on their beverage intake the day before urine sampling. The urine samples were filtered on activated charcoal and distilled before analysis. The effect of sample preparation on the isotope fractionation of urine samples was investigated by isotope ratio mass spectrometry (IRMS) of 2H/1H, which showed no influence. IRMS was also used to investigate if the ratio between the stable hydrogen isotopes (2H/1H) could provide useful data of the origin, and hence the tritium concentration, of various types of drinking water. Urinary HTO activity concentrations determined using liquid scintillation counting (LSC) were found to be below the minimum detectable activity (MDA) of 2.1 Bq⋅L−1 for most of the participants. Five of the workers actively handling organic tritiated material were found to have activity concentrations between 3.5 and 11 Bq⋅L−1, which were higher than the average value in local tap water of 1.5 ± 0.6 Bq⋅L−1. The results will be used to evaluate the radiological impact on the population from future releases of tritium resulting from the operation of the ESS.

Tritium that is released from nuclear facilities, especially from nuclear reactor units, may be the main origination of tritium in the environment. Atmospheric tritiated water (HTO) is the main chemical form of tritium that is released from nuclear reactor units. HTO in the air, drinking water and foods should be monitored routinely to protect public from the radiological hazards of tritium. Here, concentrations of HTO in the air, drinking water and foods in the vicinity of Qinshan Nuclear Power (QNP) base were measured from 2012 to 2016. And based on the concentrations of HTO measured, annual dose equivalent and collective dose equivalent for adults were calculated to evaluate the radiological hazards derived from HTO. The annual dose equivalent for adults in Qinshan and Wuyuan communities were both far below the dose limit for public exposure, and both showed an increasing trend, indicating that great attention still should be payed to the releasing of tritium from nuclear reactor units in the QNP base.

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•10

Contamination of surfaces by solid material may occur by spillage of powders, by contact between the surface and radioactive material, by the drying of radioactive liquids and solutions on the surface of the material, or by deposition from airborne radioactive material. Surface contamination may also occur by sorption of radioactive gas such as tritium, or vapor such as tritiated water. A potential radiological hazard arises from the presence of radioactive surface contamination. It can become airborne and subsequently may be inhaled, or it may be transferred by contact to the hands and subsequently to food and ingested, or it may penetrate the intact skin or enter an open wound giving rise to an internal radiological hazard. The presence of radioactive contamination at levels, which may not be a health hazard, may interfere with experimental work, leading to erroneous low-level counting results, or cross-contamination of radiochemical experiments. In this study we present the results of international comparison organized by IAEA Vienna, Austria for the tree samples spiked with unknown Alpha and Beta Activity. The source used as alpha emitter was Cm-244 and the beta emitter was Sr-90. The measurements of surface contaminated samples after calibration of the system are done with SAB-100 probe for measurement of surface contamination designed to be used with any CSP survey meter. Its phoswich scintillation detector with 100 cm2 detection area makes it an ideal tool for direct measurement of alpha and beta emitters. The high sensitivity of the system for the determination of the Gross Alpha and Beta activity makes sure detection of low values activity of samples. Our laboratory results are: for sample 01 (beta) Aβ=(1.09±0.12) Bq/ cm2 and Aβ (IAEA)=(1.21±0.01) Bq/cm2: for sample 02 (alpha) Aα=(0.69±0.07) Bq/ cm2 and Aα (IAEA)=(0.71±0.09) Bq/cm2; for sample 03 (mix alpha and beta) Aα=(0.35±0.04) Bq/cm2 and Aα (IAEA)=(0.37±0.04) Bq/cm2; Aβ = (0.76±0.08) Bq/ cm2 and Aβ (IAEA)=(0.6±0.07) Bq/cm2. As it seems our results are in good agreement with reference values given by IAEA (International Atomic Energy Agency).

A comparison of calculations of the activity of a 3H2O liquid scintillation source using the same experimental data set collected at the LNE-LNHB with a triple-to-double coincidence ratio (TDCR) counter was completed. A total of 17 laboratories calculated the activity and standard uncertainty of the LS source, using the files with experimental data. The results, as well as relevant information on the computation techniques are presented and analysed in this paper. All results are compatible, even if there is a significant dispersion between the reported uncertainties. An output of this comparison is the estimation of the dispersion of TDCR measurement results when measurement conditions are well defined. KEY WORDS FOR SEARCH Radionuclide metrology, supplementary comparison, tritium, liquid scintillation Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

This work presents the capability of digital autoradiography, a non-destructive technique, to improve diffusion parameters determination by mean of high resolution radionuclide mapping. The results show a good agreement between Cl-36 diffusion profiles acquired by digital autoradiography compared to the classic protocol based onto multi-step-abrasive-surface-peeling procedure. The digital autoradiography technique has been successfully used to localize and quantify Cl-36-labelled radiotracer on the surface of a concrete sample and into the contaminated depth. This study shows how optimized in-diffusion investigations can be performed in only 100 days to assess the diffusion parameters of Cl-36 in a low diffusive concrete sample, prepared from a composite cement (CEM V/A), while a through-diffusion experiment would take several years to reach diffusion steady state for tritiated water, considered as the reference tracer, and consequently, to allow the estimation of the diffusion parameters for Cl-36.

Li2TiO3 with excess Li (Li2+xTiO3+y) has been developed as an advanced tritium breeder. With respect to the tritium release characteristics of the blanket, the optimum grain size after sintering was less than 5 μm. Therefore, an emulsion method was developed to fabricate pebbles with this target grain size. The predominant factor affecting grain growth was assumed to be the presence of binder in the gel particles; this remaining binder was hypothesized to react with the excess Li, thereby generating Li2CO3, which promotes grain growth. To inhibit the generation of Li2CO3, calcined Li2+xTiO3+y pebbles were sintered under vacuum and subsequently under a 1% H2–He atmosphere. The average grain size of the sintered Li2+xTiO3+y pebbles was less than 5 μm. Furthermore, the tritium release properties of Li2+xTiO3+y pebbles were evaluated, and deuterium–tritium (DT) neutron irradiation experiments were performed at the Fusion Neutronics Source facility in the Japan Atomic Energy Agency. To remove the tritium produced by neutron irradiation, 1% H2–He purge gas was passed through the Li2+xTiO3+y pebbles. The Li2+xTiO3+y pebbles exhibited good tritium release properties, similar to those of Li2TiO3 pebbles. In particular, the released amount of tritiated hydrogen gas for easier tritium handling was greater than the released amount of tritiated water.

A new tritiated water measurement method with plastic scintillator pellets (PS-pellets) by using a conventional liquid scintillation counter was developed. The PS-pellets used were 3 mm in both diameter and length. A low potassium glass vial was filled full with the pellets, and tritiated water was applied to the vial from 5 to 100 μl. Then, the sample solution was scattered in the interstices of the pellets in a vial. This method needs no liquid scintillator, so no liquid organic waste fluid is generated. The counting efficiency with the pellets was approximately 48 % when a 5 μl solution was used, which was higher than that of conventional measurement using liquid scintillator. The relationship between count rate and activity showed good linearity. The pellets were able to be used repeatedly, so few solid wastes are generated with this method. The PS-pellets are useful for tritiated water measurement; however, it is necessary to develop a new device which can be applied to a larger volume and measure low level concentration like an environmental application.

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 &le, 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 (&lt, 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 &lsquo, hormetic&rsquo, 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.

An exhaust detritiation system using commercially available hollow fiber-type polyimide membrane modules, a PM system, was installed and applied for tritium recovery in the vacuum vessel purge gas of a large fusion test device. The PM system is operated annually and there were no serious malfunctions after starting the operation for approximately 2.5 y. The continuous recovery of tritiated water without the heating operation and the switching of valves as well as the regeneration operation of molecular sieves, was demonstrated. The tritium in the process gas was successfully recovered by the PM system even though the average tritium concentration at the inlet of the PM system was less than the order of 10−3 Bq/cm3. The detritiation factor and tritium recovery ratio were greater than 103 and 0.97, respectively. The tritium concentration at the outlet of the PM system was maintained in the order of 10−6 Bq/cm3 irrespective of the tritium concentration at the inlet of the PM system. Thus, the operating data indicates that the PM system has a potentially higher detritiation factor than DF = 103., The exhaust detritiation system using a polymer membrane was operated for 2.5 y., There were no serious malfunctions after starting the operation., The operating data indicates that the system has a potentially higher detritiation factor than DF = 103.

The tritium release from the ceramic materials of the DEMO Breading Blanket (BB) is a complex mechanism due mainly to the chemistry of the interface between the breeder material and the purge gas. The tritium atomic form produced inside the ceramics structure is converted into tritiated water at the surface of the breeder material due to interaction with residual moisture / water layer on the ceramics and free oxygen atoms after Li burn-up. Therefore, in contrast to the liquid BB where tritium is produced as Q2 solely, the Tritium Extraction and Recovery (TER) from any solid BB must handle both the molecular tritium and the tritiated water. Most of the processes considered for T extraction from the purge gas foresee to handle Q2O and Q2 separately and consecutively, making necessary a two-stage process for full tritium removal.

The tritium release experiments of Li4SiO4 pebbles, Li2TiO3 pebbles and Li4SiO4-Li2TiO3 biphasic pebbles were conducted to investigated the tritium release behavior of Li4SiO4-Li2TiO3 biphasic pebbles. The results indicate that the biphasic ceramic pebbles with uniform structure and small grain size exhibit good tritium release performance. The tritium release temperature is around 450 °C, and most of tritium is released in the form of tritiated water. The tritium release behavior of Li4SiO4-Li2TiO3 biphasic pebbles is controlled by the release of both Li2TiO3 and Li4SiO4, and the interfaces between Li2TiO3 and Li4SiO4 can promote the tritium release. Besides, the surface reaction is the key process affected the tritium release of the Li4SiO4-Li2TiO3 biphasic pebbles, because the release behavior is significantly affected by the composition of purge gas. Under 0.1% H2+He purge gas, with the combined effect of the two-phase interface and the isotope exchange reaction, the tritium release properties of the biphasic pebbles are promoted.

The purpose of this study was to investigate the effects of Chahuangjing, a novel traditional Chinese medicinal compound, on decorporation and radiation protection against tritiated water (HTO). Sixty male specific-pathogen-free-grade C57BL/6J mice were randomly divided into 12 groups: mice in 4 control groups were intraperitoneally injected with sterile water; mice in 4 HTO groups were intraperitoneally injected with 11.1 × 105 Bq/g of HTO; and mice in the other 4 groups were administered with HTO and a Chahuangjing compound (0.2 mL, once daily). After 1, 7, 14, and 21 days, the mice were killed and samples were collected. A liquid scintillation counting method was used for tritium measurement. A fully automated hematology analyzer was used to assess blood samples. The superoxide dismutase (SOD) and malondialdehyde (MDA) content was analyzed using commercial kits. Chahuangjing significantly increased decorporation and shortened the effective half-life of tritium. To a certain extent, Chahuangjing alleviated the HTO-induced reduction in white blood cells and elevated red blood cells after HTO exposure. Moreover, Chahuangjing alleviated the HTO-induced reduction in SOD activity and reduced MDA. Our study demonstrated that Chahuangjing can enhance the elimination of tritium and reduce free radicals to alleviate HTO-induced radiation injury.

We set out to improve the accuracy of absorbed dose calculations for in vitro measurements of the relative biological effectiveness (RBE) of tritiated water (HTO) for the clonogenic cell survival assay, also considering the influence of the end-of-track linear energy transfer (LET) of low-energy electrons.The COmputation Of Local Electron Release (COOLER) program was adopted to investigate the cell geometry and the tritium full beta-decay spectrum impact on the S-values and subsequently on the RBE of HTO for clonogenic cell survival at similar high dose rates (HDR).S-values for cells growing in suspension are usually comparable to those for adherent cells. RBEs calculated at the 10% survival fraction through the use of the average energy are almost similar to those obtained with the beta-spectrum. For adherent cells, an RBE of 1.6 was found when HTO cell survival curves were compared to acute γ-ray exposures. Irrespective of the geometrical configuration, the RBE was 2.0 when the comparison was made with similar dose rates.These results underline the importance of irradiating at equal dose rates and cell culture conditions when measuring in vitro RBE-values.

The correlation between water desorption and tritium release from Li 4 SiO 4 pebbles was studied by temperature programmed desorption. The released water and tritium from irradiated samples were monitored simultaneously. The main peak for tritium release from the irradiated samples that were exposed to air for more than a month, was shifted from 500 to about 250 °C, as compared to that from the unexposed samples. The peak temperatures for water desorption and tritium release overlapped very well, suggesting a strong correlation between the two processes. Accordingly, a two-step mechanism, involving isotope exchange between the tritium trapped on the grain surface and the surface hydroxyls (–OH), and subsequent desorption of tritiated water through recombination of the –OH/–OT groups, was proposed to explain the tritium release behavior for the air-exposed samples. It is believed that the formation and desorption of surface hydroxyl groups at 200–300 °C can affect the behavior of tritium release from Li 4 SiO 4 significantly.

A tritium imaging plate technique has been applied to visualize hydrogen distribution and examine hydrogen solubility and diffusivity in a proton-conducting oxide, Y-doped BaCeO 3 (BaCe 0.9 Y 0.1 O 3 − α ). Tritium charging of the BaCe 0.9 Y 0.1 O 3 − α specimens was carried out by a gas absorption method using partially tritiated water vapor (HTO, 3 kPa, T/H ~ 10 − 6 ) at temperatures ranging from 673 K to 873 K for a given time. After charging, tritium distributions of the surface and cross section of the halved specimens were visualized using an imaging plate technique. From the tritium concentration and distributions of the surface and cross section, hydrogen solubility and hydrogen (tritium) diffusivity of the BaCe 0.9 Y 0.1 O 3 − α specimens were determined.

The Savannah River National Laboratory has demonstrated a potential process that can be used to remove tritium from tritiated water using Pt-catalyzed molecular sieves. The process is an elemental ...

Tritium is usually measured by using a liquid scintillation counter. However, liquid scintillator used for measurement will become radioactive waste fluid. To solve this issue, we have developed a method of measuring tritium samples with plasma-treated plastic scintillator (PS)sheets (Plasma method). The radioactive sample is held between 2 PS sheets and the whole is enclosed in a a low-potassium glass vial. With the Plasma method of 2-min plasma treatment, we have obtained measurement efficiency of 48 ± 2 % for 2 min measurement of tritium except for tritiated water. The plasma treatment makes the PS surface rough and hydrophilic which contributes to improve the contact between tritium and PS. On the other hand, it needed almost 6 hours to obtain constant measurement efficiency. The reason was that the dry-up handling in the vial needed longer time to vaporize H{sub 2}O molecules than in the air. We tried putting silica gel beads into vials to remove H{sub 2}O molecules from PS sheet surface quickly. The silica gel beads worked well and we got constant measurement efficiency within 1-3 hours. Also, we tried using other kinds of PS treated with plasma to obtain higher measurement efficiencies of tritium samples.

Tritium Facility staff at Chalk River Laboratories (CRL) have successfully prepared highly tritiated water for use in radiation resistance of PEM (Proton Exchange Membrane-based)electrolyser membrane. The goal of System A was to convert a known amount of elemental tritium (HT) into tritiated water vapour using a copper(II) oxide bed, and to condense the tritiated water vapour into a known amount of chilled heavy water (D{sub 2}O). The conversion and capture of tritium using this system is close to 100%. The goal of System B was to transfer tritiated water from the containment vessel to an exposure vessel (experiment) in a controlled and safe manner. System B is based on the pushing of D{sub 2}0 with low-pressure argon carrier gas to a calibrated volume and then to the exposure vessel. A method for delivering a known and controlled amount of tritiated water has been successfully demonstrated at CRL. Using both systems Tritium Facility staff have made and distributed highly tritiated water in a safe and controlled manner. This paper focuses on how the tritiated water was produced and dispensed to the experiment.

The β-ray induced X-ray spectrometry (BIXS) is a promising technique to monitor the tritium concentration in a fuel cycle of a fusion reactor. For in-situ measurements of high level tritiated water...

Out-of-pile tritium release experiments were performed on Li4SiO4 pebbles produced from lithium hydroxide under various compositions of sweep gas (He, 1.1% H2/He) and environmental moisture conditions. The experimental results indicate that tritium gas can be released directly from “dry” Li4SiO4 under pure He gas. This phenomenon did not happen on “wet” samples, which means that the chemical form of released tritium is sensitive to moisture. Adding H2 to sweep gas may increase the overall desorption rate of tritium gas through H2 isotope exchange reaction, which occurs at a lower temperature than those of directly released tritium gas. Yet, the threshold of the H2 isotope exchange reaction is higher than the desorption reaction of tritiated water. Consequently, the effect of H2 isotope exchange reaction would reduce significantly on water adsorbed Li4SiO4 samples.

The CAPER facility at TLK originally devoted to R&D on tokamak exhaust processing has been significantly upgraded over the last years. Beside new R&D on highly tritiated water, CAPER is presently l...

Proton Exchange Membrane (PEM) type electrolysis cells have a potential use for tritium removal and heavy water upgrading. AECL is currently exposing various commercial PEM materials to both gamma (Cobalt-60 source) and beta (tritiated water) radiation to study the effects of radiation on these materials. This paper summarizes the testing methods and results that have been collected to date. The PEM materials that are or have been exposed to radiation are: Nafion 112, 212, 117 and 1110. Membrane characterization pre- and post- exposure consists of non-destructive inspection (FTIR, SEM/XPS), mechanical (tensile strength, percentage elongation, and modulus), electrical (resistance), or chemical (ion-exchange capacity - IEC). It has appeared that the best characterization techniques to compare exposed versus unexposed membranes were IEC, ultimate tensile strength and percent elongation. These testing techniques are easy and cheap to perform. The non-destructive tests, such as SEM and FTIR did not provide particularly useful information on radiation-induced degradation. Where changes in material properties were measured after radiation exposure, they would be expected to result in poorer cell performance. However, for modest γ-radiation exposure, all membranes showed a slight decrease in cell voltage (better performance). In contrast, the one β-radiation exposed membrane did show the expected increasemore » in cell voltage. The counterintuitive trend for γ-radiation exposed membranes is not yet understood. Based on these preliminary results, it appears that γ- and β-radiation exposures have different effects.« less

The activity of tritiated water has been standardized by two liquid scintillation counting methods: The CIEMAT/NIST method with the 54Mn-standard efficiency tracing and the triple-to-double coincidence ratio (TDCR) method. The samples were prepared with Ultima Gold™ AB liquid scintillation cocktail in low-potassium glass vials. In the application of the CIEMAT/NIST method, the computer program EMILIA was used to calculate the efficiency of 3H and 54Mn according to the KL1L2L3M atomic rearrangement model. And the detection efficiency of the TDCR counter was calculated using TDCR07 code, which makes it possible to allow for the potential asymmetry between the three photomultiplier tubes. The influence of stopping power and kB factor is discussed in the paper. When a power approach is adopted for the stopping power for electrons below 1 keV and kB is chosen to be 0.0075 cm/MeV, the relative deviation will be only 0.3% between the two methods.

In this study, the yields of unstable chromosome aberrations in human lymphocytes induced by β particles from low-dose HTO have been measured. HTO was mixed with heparinized blood in varying amounts so that a dose of 6.24 × 10－4 Gy to 1.23 Gy were delivered in 24 and 48 h, respectively. After 72-h culture, the dicentric yield was measured as a function of dose to the blood and compared with data from 60Co γ-radiation. Using a linear-quadratic dose-effect relation to fit the experimental data, a significant linear contribution Y = 0.062D + 0.053D2 was found. The main difference between the coefficients for β and γ-radiation was in the a values, indicating that HTO β-rays were more efficient, particularly at low doses. As per the theory of dual radiation, the relative biological effectiveness (RBE) of HTO β-particles relative to γ-rays is 2.21 at 0.06 Gy and decreases with increasing dose. Micronucleus yield at low doses was fitted to a linear equation Y = C + αD, indicating that the RBE value of MN for HTO β-rays irradiation was between 1.46 and 2.17, which is similar in shape to the chromosome aberrations experiments. Thus, β-rays were found to be more efficient in producing two lesions with single ionizing tracks at low dose.

Tritium (H-3) can discharge mainly in the form of HT and/or HTO as gaseous and/or liquid waste into the environment from the nuclear power plant, and participate in the cycle among hydrosphere, atmosphere and biosphere, which would lead to the long-term radiological effects on organisms. Thus, in the daily operation of the nuclear power station, tritium became one of the most concerned nuclides in the source term analysis. In high temperature gas-cooled reactors (HTGRs), tritium was mainly generated by the ternary fission reaction of heavy nuclei in the fuel and neutron activation reaction of impurities like lithium-6 (Li-6), lithium-7 (Li-7) and boron-10 (B-10) in the graphite matrix, carbon bricks, etc. Tritium would be resorted completely in the intact tristructural-isotropic (TRISO) coated particles, while tritium in the graphite can diffuse into the primary loop depending on the local temperature. In the helium purification system of a typical HTGR, the molecular adsorber can adsorb the tritium in the primary coolant, and then the tritiated water was formed from the regeneration and desorption process of the molecular adsorber. Meanwhile, since the high permeability of tritium at a high temperature, it can permeate into the secondary loop through stainless steel heat exchange tube from the primary loop, and entered into the environment with leakage of the secondary water. Therefore, it was very important to analyze the production, transport and release mechanism of tritium for the estimation of the inventory and distribution of tritium in a nuclear power plant. With the rapid development of nuclear energy and the commercial application of HTGRs, tritiated water treatment technologies attracted more attention in the field of radioactive nuclear waste. Current paper will introduce and summarize general tritiated water treatment technologies, including water distillation, tritium sorbent process, palladium membrane reaction (PMR), and combined electrolysis catalytic exchange (CECE).

Luminous marine bacteria are widely used in bioassays with luminescence intensity being a physiological parameter tested. The purpose of the study was to determine whether bacterial genetic alteration is responsible for bioluminescence kinetics change under low-dose radiation exposure. The alpha-emitting radionuclide 241Am and beta-emitting radionuclide 3H were used as the sources of low-dose ionizing radiation. Changes of bioluminescence kinetics of Photobacterium phosphoreum in solutions of 241Am(NO3)3, 7 kBq/L, and tritiated water, 100 MBq/L, were studied; bioluminescence kinetics stages (absence of effect, activation, and inhibition) were determined. Bacterial suspension was sampled at different stages of the bioluminescent kinetics; the doses accumulated by the samples were close or a little higher than a tentative limit of a low-dose interval: 0.10 and 0.85 Gy for 241Am, or 0.11 and 0.18 Gy for 3H. Sequence analysis of the 16S ribosomal RNA gene did not reveal a mutagenic effect of low-dose alpha and beta radiation in the bacterial samples. Previous results on bacterial DNA exposed to low-dose gamma radiation (0.25 Gy) were analyzed and compared to those for alpha and beta irradiation. It is concluded that bioluminescence activation and/or inhibition under the applied conditions of low-dose alpha, beta and gamma radioactive exposure is not associated with DNA mutations in the gene sequences tested.

Uncertainties remain regarding the fate of atmospheric tritium after it has been assimilated in grasslands (ryegrass) in the form of TFWT (Tissue Free Water Tritium) or OBT (Organically Bound Tritium). One such uncertainty relates to the tritium forms discrimination during transfer from TFWT to OBT resulting from photosynthesis (OBTphoto), corresponding to the OBTphoto/TFWT ratio. In this study, the OBT/TFWT ratio is determined by experiments in the laboratory using a ryegrass model and hydroponic cultures, with constant activity of tritium in the form of tritiated water (denoted as HTO) in the “water” compartment (liquid HTO) and “air” compartment (HTO vapour in the air). The OBTphoto/TFWT ratio and the exchangeable OBT fraction are measured for three parts of the plant: the leaf, seed and root. Plant growth is modelled using dehydrated biomass measurements taken over time in the laboratory and integrating physiological functions of the plant during the first ten days after germination. The results suggest that there is no measurable discrimination of tritium in the plant organic matter produced by photosynthesis.

Effects of Americium-241 (241Am), alpha-emitting radionuclide of high specific radioactivity, and tritium (3H), beta-emitting radionuclide, on luminous bacteria Photobacterium phosphoreum were compared. Bioluminescence intensity served as a marker of bacterial physiological activity. Three successive stages in the bioluminescence response to 241Am and 3H were found under conditions of lowdose irradiation: (1) absence of effects, (2) activation, and (3) inhibition. They were interpreted in terms of bacterial response to stressfactor as stress recognition, adaptive response/syndrome, and suppression of physiological function (i.e. radiation toxicity). Times of bioluminescence activation (TBA) and inhibition (TBI) were suggested as parameters to characterize hormesis and toxic stages in a course of chronic low-dose irradiation of the microorganisms. Values of TBA and TBI of 241Am were shorter than those of 3H, revealing higher impact of alpha-irradiation (as compared to beta-irradiation) under comparable radiation doses. Increases of peroxide concentration and NADH oxidation rates in 241Am aquatic solutions were demonstrated; these were not found in tritiated water. The results reveal a biological role of reactive oxygen species generated in water solutions as secondary products of the radioactive decay. The study provides a scientific basis for elaboration of bioluminescence-based assay to monitor radiotoxicity of alpha- and beta-emitting radionuclides in aquatic solutions.

Low concentration tritium permeation experiments have been performed on uncoated F82H and Er2O3-coated tubular samples in the framework of the Japan-US TITAN collaborative program. Tritium permeability of the uncoated sample with 1.2 ppm tritium showed one order of magnitude lower than that with 100% deuterium. The permeability of the sample with 40 ppm tritium was more than twice higher than that of 1.2 ppm, indicating a surface contribution at the lower tritium concentration. The Er2O3-coated sample showed two orders of magnitude lower permeability than the uncoated sample, and lower permeability than that of the coated plate sample with 100% deuterium. It was also indicated that the memory effect of ion chambers in the primary and secondary circuits was caused by absorption of tritiated water vapor that was generated by isotope exchange reactions between tritium and surface water on the coating.

Monte Carlo track chemistry simulations were used to determine the yields (or G-values) of hydrogen peroxide in the radiolysis of neutral water and dilute aqueous bromide solutions by low linear energy transfer (LET ∼ 0.3 keV μm−1) radiation (e.g., γ-rays from 60Co, fast electrons or high-energy protons) and tritium β-particles (mean LET ∼ 6 keV μm−1) at 25 °C. We investigated the influence of Br− ions, as selective scavengers of ˙OH radical precursors of H2O2, on the inhibition of G(H2O2) for these two types of radiation. Studying this system under a wide range of Br− concentrations (5 × 10−7 to 0.2 M) and using a well-accepted mechanism for radiolysis in the presence or absence of air, we examined the chemical changes in the scavengeability of H2O2 produced by 300 MeV irradiating protons (used in this work to reproduce the effects of 60Co γ/fast electron radiolysis) and tritium β-electron radiolysis. We found that these changes could be related to differences in the initial spatial distributions of radiolytic species (i.e., the structure of the electron tracks, the low-energy β-electrons of tritium depositing their energy almost entirely as cylindrical “short tracks” and the energetic Compton electrons produced by γ-radiolysis forming mainly spherical “spurs”), in full agreement with previous experimental and theoretical work. Simulations showed that the short track geometry of higher LET tritium β-electrons in both water and aqueous bromide solutions favored a clear increase in G(H2O2) compared to 60Co γ-rays. Moreover, the presence of oxygen was seen to scavenge hydrated electrons (eaq−) and H˙ atoms on the ∼10−7 s time scale, thereby protecting H2O2 from further reactions with these species in the homogeneous stage of radiolysis. This protection against eaq− and H˙ atoms therefore led to an increase in the long time H2O2 yields, as seen experimentally. Finally, for both deaerated and aerated solutions, the H2O2 yield in tritium β-radiolysis was found to be more easily suppressed than in the case of cobalt γ-radiolysis, and interpreted by the quantitatively different chemistry between spurs and short tracks. These differences in the scavengeability of H2O2 precursors in passing from 300 MeV irradiating protons to tritium β-electron irradiation were in good agreement with experimental data, thereby lending strong support to the picture of tritium β-radiolysis in terms of short tracks of high local LET.