Search results for "Tritiated water"
showing 10 items of 11 documents
Determination of Diffusion Parameters by a Computer Code (FDP) Based on Mathematica 6.0
2010
A computer code named Fitting for Diffusion Parameters (FDP) based on Mathematica 6.0 has been developed for modeling through- and out-diffusion experiments. FDP was used to determine the diffusion coefficients (De ) and the rock capacity factors (α) for tritiated water (HTO) and 22 Na+ and the distribution coefficient (Kd ) of 22 Na+ in Opalinus Clay (OPA). The values for De and α were obtained by fitting the results of experimental data of both transient and steady-state phases to the analytical solution of accumulated activity. The quality of the parameters De and α was tested by using them as input parameters in the equation of flux. Moreover, the diffusion parameters of HTO and 22 Na+ …
Self radiolysis of tritiated water
2003
The mechanism of water radiolysis implies several reactions and depends on many parameters such as the radiation characteristics (type of radiation, energy…), the temperature and the chemical composition of irradiate water. Thus it is very difficult to foresee, without experimental data, the overall effect of these parameters. If radiolysis of pure water under γ rays or α particles has been widely studied, it is not the case for self radiolysis of tritiated water (low energy β− particles radiation). In order to fill this lack of experimental knowledge and to understand the radiolysis of stored tritiated water produced in tritium plants, we studied the evolution of hydrogen and oxygen concen…
The preparation of (14C) and [3H] labelled benzene oxide
1977
Benzene oxide -[U-14C] was prepared from benzene -(U-14C) by modifications of methods described for the inactive compound. Benzene oxide-[3.6–3H] was prepared by decomposition of 3.6-bis-trimethylsilyl-1,4-cyclohexadiene with tritiated water. bromination of the 1,4-cyclohexadiene-[3,6-3H] so obtained. epoxidation and dehydrobromination. With the latter method benzene oxide-[3,6–3H] can be prepared at a much lower cost and higher specific activity than benzene oxide-[U-14C].
Self-Radiolysis of Tritiated Water Stored in Zeolites 4A: Production and Behavior of H 2 and O 2
2015
International audience; Radiolysis of confined water and self-radiolysis of tritiated water give rise to several unanswered questions. To take into account this double specificity, we studied systems of zeolites 4A containing tritiated water at different water loading ratios. Two tritiated waters were synthesized at the volumetric activities of 27 and 60 TBq L −1. For each one, five samples were prepared, differentiated by their water loading ratios, expressed in percentage, close to 4%, 7%, 11%, 14%, and 19%. The study of the radiolysis in those systems revealed a double role of zeolites 4A: first, they increase the decomposition of water. Then they enhance the recombination of the major s…
Radioactively labelled epoxides. Part IV. Tritium labelled α- and β-methyl styrene oxides
1983
Tritium labelled α-methyl styrene oxide (2-methyl-2-phenyloxirane) and cis- and trans-β-methyl styrene oxides (Z- and E-2-methyl-3-phenyl oxirane) have been prepared using tritiated water as the inexpensive source of tritium. The two geometrical isomers of β-methyl styrene oxide were synthesized by a sequence of reactions which led to stereochemically pure products, and obviated any need to separate the isomers.
Bipolar electrolysis for tritium recovery from weakly active tritiated water
2001
Abstract Detritiation facilities produce low activity tritiated water from which tritium cannot be recovered. Bipolar electrolysis, based on the electrochemical permeation of hydrogen and its isotopes through Pd–Ag alloy membranes, allows tritiated water enrichment together with negligible gaseous tritium release. Our purpose is to enrich water from 500 Ci/l (1.85×1013 Bq/l) to more than 2000 Ci/l (7.40×1013 Bq/l). We first describe the principle of bipolar electrolysis and its application to isotopic enrichment. The experimental part of this work consists of the determination of the isotopic separation factors. From these experimental values, we simulated the working of an operational cell…
Neptunium(V) Sorption and Diffusion in Opalinus Clay
2009
The sorption and diffusion behavior of 8 x 10(-6) M Np(V) in Opalinus Clay (OPA) with synthetic pore water (pH 7.6) as mobile phase was studied under ambient conditions by batch and diffusion experiments, respectively. The Kd value determined by batch experiments with OPA suspensions is equal to 0.025 +/- 0.005 m3/kg. The diffusion-accessible porosity epsilon of intact OPA as determined by through- and out-diffusion experiments with tritiated water (HTO) is equal to 0.15 +/- 0.01. The diffusion coefficient De and the rock capacity factor alpha of 22Na+ in OPA were measured by through-, out-, and in-diffusion experiments and asserted the reliability of these diffusion techniques. For the dif…
Adsorption of water in Na-LTA zeolites: an ab initio molecular dynamics investigation
2021
The very wide range of applications of LTA zeolites, including the storage of tritiated water, implies that a detailed and accurate atomic-scale description of the adsorption processes taking place in their structure is crucial. To unravel with an unprecedented accuracy the mechanisms behind the water filling in NaA, we have conducted a systematic ab initio molecular dynamics investigation. Two LTA structural models, the conventional Z4A and the reduced one ZK4, have been used for static and dynamic ab initio calculations, respectively. After assessing this reduced model with comparative static DFT calculations, we start the filling of the α and β cages by water, molecule by molecule. This …
Basic study of influence of radiation defects on tritium release processes from lithium silicates
1997
The radiolysis of Li2SiO3 and Li4SiO4 was studied using the chemical scavengers method (CSM), thermoluminescence, lyoluminescence, electron spin resonance and spectrometric methods. The influence of the absorbed dose and many another parameters such as: irradiation conditions, sample preparation conditions and concentration of impurities on the accumulation rate of each type RD and RP were studied. Several possibilities for reducing the radiolysis of silicates were discussed. It has been found that tritium localization on the surface and in grains proceed by two different mechanisms. Tritium thermoextraction from the surface proceeds as chemidesorption of tritiated water, but from the bulk …
Radioactively labelled epoxides. Part III. Tritium labelled steroid 16α, 17α-epoxides
1980
Tritium labelled (17-3H) 16α, 17α-epoxy-androst-4-en-3-one and 16α, 17α-epoxy-estra-1,3,5(10)-trien-3-ol have been prepared on a large scale (200-300 mg amounts) with efficient (i.e. activity of product exactly predictable) introduction of label. The preparative method is very inexpensive, since the tritium derives from tritiated water, the steroid starting materials are readily available, and high yields are obtained in all steps.