Tritiated Hydrogen Gas Research Articles

Tritium Concentrations in Pine Needle, Litter and Soil Samples.

Samples of pine needle, litter and soil samples collected in/around Akita City and Rokkasho Village in 1989 were analyzed for both free water 3H (FWT) and organically-bound 3H (OBT). The FWT concentrations decrease in the order, litter or soil > pine needle. FWT concentrations in soil depend on the moisture content, and tend to increase with decreasing soil moisture content. This relationship is consistent with the observation that FWT in the soil increases with oxidation of atmospheric tritiated hydrogen gas (HT) and decreases with rainwater dilution. The OBT concentrations increase in the order pine needle < litter < soil at most of the sampling locations. This suggests that historically high soil 3H concentrations may be reflected as high OBT concentrations in soils of the present.

Coal liquefaction mechanism using a tritium tracer method

AbstractTo determine the behavior of hydrogen in tetralin, the reaction of tetralin with tritiated gaseous hydrogen was studied in a flow reactor at 400–450°C, 2.5–9.8 MPa for various residence times. The amount of hydrogen exchange between tetralin and tritiated hydrogen was estimated from the balance of hydrogen and tritium. Although yields of methylindan and naphthalene, and the hydrogen‐exchange ratio (HER) of tetralin increased monotonously with residence time, these values were scarcely influenced by the reaction pressure at every temperature. It was thought that the formation of tetralyl radicals in this system would be the rate‐determining step for both the conversions of tetralin into methylindan and naphthalene, and the hydrogen exchange of tetralin. Conversions of tetralin into methylindan and naphthalene, and the hydrogen‐exchange reaction using the autoclave were very close to those using the flow reactor.

Elucidation of hydrogen transfer mechanisms in coal liquefaction using a tritium tracer method: Effects of solvents on hydrogen exchange reactions of coals with tritiated molecular hydrogen

To estimate the hydrogen mobility of coal and solvent quantitatively, reactions of tetralin, decalin and 1-methylnaphthalene with tritiated gaseous hydrogen in the absence and presence of Wandoan coal were performed under conditions generally used for coal liquefaction: 300–400°C, initial H 2 pressure 5.9 MPa. Tritium in the gas phase was transferred to coal and solvent mainly through hydrogen exchange and slight hydrogen addition. The amount of hydrogen exchanged between the gas phase, coal and solvents was estimated from hydrogen and tritium balances. At 400°C and 120 min, coal conversion in the presence of tetralin, decalin and 1-methylnaphthalene was 87, 45 and 54%, respectively. Under these conditions, the amount of hydrogen exchanged between the gas phase and coal decreased in the order 1-methylnaphthalene (1.38 g 30 g −1 of coal) > tetralin (0.85 g 30 g −1 of coal) > decalin (0.72 g 30 g −1 of coal). Compared with the amount of hydrogen exchanged, the amount of hydrogen added from the gas phase to the coal was smaller than 0.07 g in each solvent. Coal hydrogen exchange reactions in the presence of tetralin or decalin were similar to those in the absence of solvent. On the contrary, remarkable hydrogen exchange with coal in the presence of 1-methylnaphthalene occurred with a rise from 350 to 400°C. Further, a significant amount of 1-methylnaphthalene decomposed to naphthalene and methane in this temperature range, while hydrogen addition from 1-methylnaphthalene to coal did not occur. This suggests that hydrogen exchange reactions among the gas phase, coal and 1-methylnaphthalene proceeded by radical chain mechanisms, with the supply of radicals from coal.

Pyrolysis mechanism of pitch for carbon fiber using tritium tracer method

Tritium has been introduced into three coal tar pitches and a naphthalene pitch by two methods, one by isotope exchange with tritiated water using Pt/Al 2O 3 catalyst, and the other by hydrogenation with tritiated gaseous hydrogen using Ni-Mo/Al 2O 3 catalyst. The tritium-labelled pitches were carbonized up to 1000°C under nitrogen atmosphere. The release behaviors of hydrogen and tritium during the carbonization of tritiated pitches were investigated by comparing the rates of dehydrogenation and detritiation. The results indicate that the hydrogen introduced into the pitch by the isotope exchange is released more rapidly than the original hydrogen in the pitch while the hydrogen introduced into the pitch by the isotope addition is slightly more difficult to release relative to the original hydrogen in the pitch during the pyrolysis of the pitch. Moreover, it was clarified that the extent of development of optically anisotropic texture of the pitch is related not to the hydrogen exchange ratio but to the rate of hydrogen release during pyrolysis.

The derived emission limit for tritiated hydrogen gas from the Darlington Tritium Removal Facility

The derivation of the emission limit for tritiated hydrogen gas (HT) from Tritium Removal Facility is described using the model CEDM-HT. This compartment model assumes equilibrium between HT in air and tritium oxide (HTO) in the soil resulting from HT oxidation by soil bacteria. Subsequent transfer of this HTO occurs to air and food, resulting in dose to people. The factors taken into account in determining the critical group and the dose and emission limit calculations are described. The consumption of local-grown fruits and root vegetables was found to be potentially the major contributor to adult dose resulting from HT emissions. For young children, milk consumption is also potentially significant.

Tritiated Hydrogen Gas Storage Systems for a Fusion Plant

This paper reports that USSI INGENIERIE has carried out a study financed by European Communities Commission concerning the NET/ITER project, on tritium Fuel Management and Storage systems of the International Thermonuclear Experimental Reactor. A processing block diagram for hydrogen isotopes represents all interfaces and possible links between these systems and tritiated gas mixtures flowing through the Fusion plant. Large quantities of hydrogen isotopes (up to several thousand moles of protium, deuterium and tritium) in gaseous form associated with torus fuelling and exhaust pellet injection, and neutral beam injection, must be stored and managed in such a plant.

Theory of separation of ternary hydrogen isotope by thermal diffusion process including isotope exchange reaction.

An advanced theory of separation by the thermal diffusion method is proposed which accounts for isotope exchange reactions on the surface of the hot wire of the separation unit in a ternary isotopic mixture such as the D2-HD-H2 system or the T2-HT-H2 system. The theory has been developed in order to evaluate the performance of recovery of tritium and the separation rate from tritiated hydrogen gas by this process.The proposed theory can be applied not only to the batch process (total reflux process) but also to the continuous draw-off process for the simulation of mechanisms for D- or T-enrichment from a mixture of hydrogen isotopes. A theoretical model is derived on the basis of a ternary system, and the concept of ternary transport relations, a thermal diffusion coefficient correction factor and the effect of the isotope exchange reaction on the hot wall surface are introduced. Although the model is formally for a ternary system, the theory is also applicable even if the isotopic concentration of one or two components is extremely low.Overall separation performance decreases due to the isotope exchange reaction as compared with that with no reaction. It is very important to know that the existence of the T2 molecule and also of the isotope exchange reaction play significant roles in the separation performance of tritium, even at a tracer level of tritium.

4‐3H]‐labelling of the calcium ionophore A 23187 (calcimycin)

Abstract[4‐3H‐labelled]‐A 23187 (or calcimycin) has been obtained as a magnesium salt from the corresponding 4‐bromo derivative using tritiated hydrogen gas in the presence of 10% Pd/C catalyst. The specific radioactivity proved to be 50.6 Ci/mmole (1872.2 GBq/m mole).

Metabolism and Dosimetry of Tritium from Tritium Gas Contaminated Surfaces

Experiments by Hutchin and Vaughan on rats and by Eakins et al. on humans have shown that a surface contaminated by tritiated hydrogen gas (T2) that is brought into contact with intact skin will re...

A Discriminating Tritium Monitor Engineered for Tritium Handling Facility Applications

Tritium instrumentation is required for the protection of personnel in any facility handling significant quantities of tritium. In such facilities, in a chronic or accidental tritium release situation, tritium may be present in the air as tritiated hydrogen gas (HT, DT, T2) or tritiated water vapour (HTO, T2O, DTO). For health protection purposes, the airborne tritium concentration of each species should be determined separately since the two species represent very different radiological hazards.This paper describes a tritium monitor that is capable of measuring the airborne concentration of tritium species in the range from 0.037 MBq/m3 (1 µCi/m3) to 7.4×104 MBq/m3 (2.0×106 µCi/m3) with a resolution of 0.074 MBq/m3 (2 µCi/m3) in the lowest range. The measurement principle is based on the separation of tritium species by a permeable membrane and the measurement of sample air activities by conventional ion chamber based tritium monitors.

HT/HTO Conversion in Mammals

This paper describes a study on metabolism of inhaled tritiated hydrogen gas (HT) in mammals. Rats and human volunteers were exposed to HT gas for periods from one minute to ten minutes. The amount...

HT/HTO conversion in mammals

This paper describes a study on metabolism of inhaled tritiated hydrogen gas (HT) in mammals. Rats and human volunteers were exposed to HT gas for periods from one minute to ten minutes. The amount...

Tritium solubility in SUS-316 stainless steel

Tritium solubility in SUS-316 stainless steel was determined with a gas absorption method, in which tritium gas diluted by protium was used. The tritium absorption experiments were carried out at temperatures of 703, 804 and 903 K under pressures of 10, 30, 50 and 100 torr of tritiated hydrogen gas. The radioactivity of tritium dissolved in the specimen was measured by the method of liquid scintillation counting. The tritium solubility was derived from the experimental data by taking into consideration of isotopic equilibrium among H 2, T 2 and HT molecules. The determined tritium solubility can be expressed by the equation: C T=1.94×10 −7 exp − 10.2 RT/kJ p 1 2 T 2 mol T2/cm 3 Pa 1 2

Sorption behavior of hydrogen gas and tritiated hydrogen gas on potassium-carbon intercalation compounds

The sorption behaviors of hydrogen gas at 77 K on several different potassium-carbon intercalation compounds (KC x ) have been studied. Samples of KC x were prepared from petroleum-coke carbons heat-treated at 800, 1000, 1500 and 2300°C by the modified two-bulb method. The isotherms of hydrogen absorption and the isotropic H 2-HT partition coefficients between the absorbed phase and the gas phase determined on them were found to be considerably influenced by the composition of KC x as well as the heat-treatment temperature (HTT) of the starting carbon materials. In order to account for such behavior, which is not only different from those of ordinary compounds prepared from graphite but inconsistent with the so-called KC 8-KC 24 mixture model, a possibility is suggested that there may exist an absorptive intermediate phase between KC 8 and KC 24 in the case of KC x compounds prepared from low-HTT-carbons.