Tritiated Species Research Articles

Material Studies to Reduce the Tritium Memory Effect in BIXS Analytic Systems

Beta-induced X-ray spectrometry (BIXS) is a promising method for activity monitoring of tritiated gas species. BIXS systems measure bremsstrahlung and characteristic X-rays generated by interactions of beta decay electrons with surfaces within the measurement chamber. BIXS and other highly sensitive methods such as ionization counting are limited in accuracy by the tritium memory effect, a preconditioning dependent background signal caused by the sorption of tritium on surfaces. In this work, different surface materials have been investigated aiming at reducing the tritium memory effect while providing a high bremsstrahlung yield. A modular BIXS setup was developed that allows the consecutive investigation of different measurement cells utilizing the same detector while protecting it from contamination during cell exchanges. An uncoated stainless steel cell was compared to cells coated with Au, Ir, Ti-W, Ti-Au-Al, and Ti-Au-Cu layer systems. The sample cells were repeatedly exposed to 1100 Pa of molecular tritium. The development of the resulting memory effect was measured during the evacuation between consecutive exposures. Additionally, the background signal decay was investigated in a long-term measurement after the last exposure. In this presentation, the measurement results of the relative tritium memory effect from various surfaces will be shown. The lowest memory effect was measured for the gold-coated sample cell, reaching a background signal equal to (0.83 ± 0.14)% of the signal during exposure after a total dosage of 21.33 × 104 Pa h.

Dimensioning of ideal membrane cascade systems for the separation of binary gas mixtures for nuclear fusion applications

In the DEMO reactor highly efficient separation systems are required for the recovery of tritiated species to ensure a continuous re-fuelling of the plasma. For some of these systems, porous inorganic membranes have been proposed due to their promising modularity and cost-effectiveness for gas separation. For instance, zeolite membranes have been considered for the pre-concentration of Q2 in He (Q = H, D, T) in the European helium-cooled pebble bed (HCPB) to decrease the dimensions and costs of Pd/Ag membranes implemented downstream. Due to the similar sizes and masses of Q2 and He, the separation is limited with one membrane, hence a membrane cascade is required to achieve the desired performance requirements. In this paper, a numerical model is presented, which was developed to calculate the number of stages, surface area and power consumption of a membrane cascade using as input parameters the selectivity of the membrane α, permeances Π, pressures-ratio γ and the target separation requirements, the enrichment factor E and recovery fraction R. A sensitivity study was conducted to evaluate the impact of these parameters on the dimensioning of the membrane cascade.The pre-concentration of H2 in He using the zeolite membrane cascade with αH2/He=2 was first used as reference scenario for an inlet flow of Ffinj=8.06×103m3h−1 with E≥20 and R≥90%. The resulting membrane cascade consists of 16 stages, with 2563 m2 and 33.8 MW. For an improved selectivity of α = 10, the membrane cascade would have only 6 stages, with 260 m2 and 6 MW. The sensitivity analysis revealed that the cost-effectiveness and technological relevance of a membrane cascade are highly dependent on α, E and R.

Comparison of MFI-ZSM5 and NaA zeolite-type tubular membranes for the separation of water vapour from helium for tritium processes in future fusion reactors

Zeolite membranes have been increasingly used for gas separation applications, where the most studied are the MFI and NaA types. Typically, NaA membranes are used for dehydration applications whereas MFI are used for the separation of large/small molecules (e.g., CO2/H2). In the Tritium Laboratory Karlsruhe (TLK), both NaA and MFI-ZSM5 were selected for tritium processes where both molecular and oxidized tritiated species diluted in helium have to be processed in a continuous mode, as it is the case of the Tritium Extraction System of the Helium Cooled Pebble Bed breeding blanket. This paper presents and discusses the results obtained for the separation of a binary mixture of water vapour and helium, down to 0.2vol%, where hydrogen replaces its radioactive counterpart. These experiments were performed in the temperature range between 25 and 100°C. NaA demonstrates much better performances for feed concentrations ≥5vol%, eventually reaching separation factors higher by a factor of 100 than that of MFI-ZSM5. However, the MFI-ZSM5 membrane must be selected instead when moisture levels are ≤1vol%. In fact, at these conditions, the H2O/He separation factor for NaA barely exceeds 2, whereas it can be as high as 9.6 for MFI-ZSM5. Moreover, rather high permeances for H2O of around 1–2μmolm−1s−2Pa−1 were measured for both membranes. In the case of helium, the permeances were highly dependent on the temperature for high water contents, reaching values as low as 1×10−3μmolm−1s−2Pa−1 for the NaA membrane.

Numerical analysis of H2/He gas separation experiments performed with a MFI-type tubular zeolite membrane

Zeolite membranes were identified to be used in the future fusion reactors to separate traces of tritiated species from large helium flows. Due to the lack of data in the literature, separation experiments with helium, hydrogen and water vapor have been performed in the Tritium Laboratory Karlsruhe (Germany). The obtained results shall be used to predict performances at reactor scale. Therefore, a simulation tool of a permeator has been developed to perform calculations ab-initio of its performance at several experimental conditions. In the present work, numerical results for the binary mixture hydrogen/helium at different concentrations are compared with the experimental results obtained with a zeolite MFI-ZSM5 tubular membrane, where separation factors below 2 were measured for different cuts. Very good agreement between experiments and simulations was observed. This agreement gives confidence to integrate this numerical tool into a membrane cascade simulator, in development in the TLK, toward the modeling of the zeolite membranes’ performances at reactor scale.

Adsorption Characteristics of Water Vapor on Gear-Pellet and Honeycomb-Pellet Types of Adsorbents Containing A-Type Zeolite

It is necessary to recover or process tritiated species that are extensively coexistent in nuclear fusion installations. A conventional way to recover tritium release to atmosphere is catalytic oxidation of tritiated species and adsorption of tritated water vapor on adsorbents with high surface areas. However, pressure loss would become more serious with increase in the size of adsorbent beds, which could lead to greater power needs for ventilation systems. Therefore, new adsorbents with low pressure loss and high surface areas need to be developed and utilized for such large-scale adsorption systems. Thus, the authors tested new types of adsorbents, which are gear-type and honeycomb-type pellet adsorbents. The experimental results reveal that the gear-type pellet adsorbents have larger adsorption capacity than the honeycomb-type pellet adsorbent. It was also found that the gear-type MS4A adsorbent possesses larger adsorption capacity than other adsorbents tested in this work. Furthermore, it was found that new types of adsorbents are lower pressure than conventional-type of adsorbents. Among the new adsorbents studied in this work, the gear-type MS4A adsorbent appears to be most promising for the application to the adsorption systems in terms of adsorption capacity and adsorption rate.

Development, description and validation of a Tritium Environmental Release Model (TERM)

Tritium is a radioisotope of hydrogen that exists naturally in the environment and may also be released through anthropogenic activities. It bonds readily with hydrogen and oxygen atoms to form tritiated water, which then cycles through the hydrosphere. This paper seeks to model the migration of tritiated species throughout the environment – including atmospheric, river and coastal systems – more comprehensively and more consistently across release scenarios than is currently in the literature. A review of the features and underlying conceptual models of some existing tritium release models was conducted, and an underlying aggregated conceptual process model defined, which is presented. The new model, dubbed ‘Tritium Environmental Release Model’ (TERM), was then tested against multiple validation sets from literature, including experimental data and reference tests for tritium models. TERM has been shown to be capable of providing reasonable results which are broadly comparable with atmospheric HTO release models from the literature, spanning both continuous and discrete release conditions. TERM also performed well when compared with atmospheric data. TERM is believed to be a useful tool for examining discrete and continuous atmospheric releases or combinations thereof. TERM also includes further capabilities (e.g. river and coastal release scenarios) that may be applicable to certain scenarios that atmospheric models alone may not handle well.

Zeolite membranes and palladium membrane reactor for tritium extraction from the breeder blankets of ITER and DEMO

While the tritium technology for the inner DT fuel cycle of fusion reactors shall be demonstrated in ITER, the tritium management in the breeder blanket remains very challenging. Most of the process options rely on ad(b)sorption/desorption cycles, using dedicated packed beds to handle separately the molecular and oxide forms of tritium. This approach seems satisfactory for ITER, but seems difficult to scale up to DEMO. The alternative use of a catalytic membrane reactor in combination with inorganic membranes would simplify and improve the overall tritium management. Zeolite membranes should enable in a single step the pre-concentration of all tritiated species. This tritium enriched stream could be afterwards processed using PERMCAT (catalytic Pd-based membrane reactor) to finally recover the tritium in its pure molecular form. This paper discusses at the conceptual level such approach. The latest experimental results on zeolite membrane and multi-tube PERMCAT reactor are presented. Next R&D activities for technical scale demonstrations and refined simulation tools are proposed to finally estimate the sizes of the components to be operated in ITER and DEMO.

Computation and comparison of Pd-based membrane reactor performances for water gas shift reaction and isotope swamping in view of highly tritiated water decontamination

In a D–T fusion machine, due to the possible reaction between tritium and oxygen, some potential sources of highly tritiated water (HTW) can be identified. Therefore, a dedicated detritiation process has to be assessed either for economic and safety reasons. In this view, the use of a Pd-based membrane reactor performing isotopic exchange reactions can be considered since hydrogen isotopes exclusively permeate the Pd–Ag membrane and their exchange over the catalyst realizes the water detritiation.In this activity, the treatment of highly tritiated water, generated by an ITER-like machine (i.e. 2kg of stoichiometric HTO containing up to 300g of tritium), via a Pd-membrane reactor is studied in terms of decontamination capability. Especially, a parametric analysis of two processes (water gas shift and isotopic swamping) performed in a Pd-based membrane reactor is carried out by using two mathematical models previously developed and experimentally verified. Particularly, the effect of the reactor temperature, the membrane thickness, the reaction pressure and the protium sweep flow-rate is investigated. Moreover, a comparison in terms of the decontamination factor and the number of reactors necessary to detritiate the HTW are provided. Generally, the results reveal a higher decontamination capability of the WGS reaction respect with the IS (maximum DF values of about 120 and 1.6 in the case of WGS and IS, respectively). However some drawbacks, mainly related with the formation of tritiated species, can occur by performing the WGS.

Accurate calibration of the laser Raman system for the Karlsruhe Tritium Neutrino Experiment

The Karlsruhe Tritium Neutrino (KATRIN) experiment aims to measure the neutrino mass via high-precision electron spectroscopy of the tritium β-decay with a sensitivity of mν=200meV/c2 (90% C.L.). This can only be achieved if systematic uncertainties are minimized. An important parameter is the isotopic composition of the tritium gas used as the gaseous β-electron source, which is measured inline by Raman spectroscopy. The KATRIN experiment requires a measurement trueness of better than 10% of said composition; to achieve this, accurate calibration of the Raman system for all hydrogen isotopologues (H2, HD, D2, HT, DT, T2) is required. Here we present two independent calibration methods, namely (i) a gas sampling technique, which promises high accuracy, but which is difficult to apply to tritiated species; and (ii) an approach via theoretical Raman signals (theoretical intensities plus spectral sensitivity), which in principle includes all six isotopologues. For the latter method we incorporated ab initio off-diagonal matrix elements of the polarizability from the literature; these have been verified by depolarization measurements. The system’s spectral sensitivity was determined by a NIST-traceable SRM2242 luminescence standard. Both methods exhibited their individual merits and difficulties, but in cross calibration proved to be successful: a comparison for the non-radioactive isotopologues (H2, HD, D2) yielded agreement to better than 2% for the relative Raman response function. This is within the estimated (dominant) uncertainty of the theoretical Raman signal approach of about 3%. Therefore, one can be confident that, when using this approach, the trueness requirement of 10% for the KATRIN-relevant species (T2, DT, D2 and HT) will in all likelihood be exceeded.

Design of Pd-based membrane reactor for gas detritiation

The development of a Pd-based membrane reactor to be applied in processes for tritium removal from various gaseous streams of tokamak systems has been carried out. In particular, the membrane reactor has been designed for decontaminating soft housekeeping wastes of JET. This membrane reactor consists of Pd–Ag permeator tube fixed in a finger-like mode into a stainless steel shell. The feed stream (gases to be detritiated) is fed inside the membrane lumen where the isotopic exchange takes place on to a catalyst bed while pure hydrogen (protium) is sent in countercurrent mode in the shell side. The feed stream consists of 200 Ncm 3 min −1 of helium with 10% of tritiated water (tritium content 1.11 × 10 8 Bq h −1). The membrane reactor design has been based on a simplified calculation model which takes into consideration the very low tritium content of the gas to be processed and the complete oxidation of the tritiated species in the feed stream. The model considers a tubular Pd–Ag membrane divided into finite elements where the mass balances are performed according to both the thermodynamic equilibrium reactions and permeation rates through the membrane of the hydrogen isotopes. The reactor model has permitted to verify that a Pd–Ag commercial tube of diameter 10 mm, length 500 mm and wall thickness 0.150 mm is capable to attain a decontamination factor larger than 10. A new mechanical design of the Pd membrane reactor has been also developed: especially, harmful mechanical stresses of the long permeator tube consequent to the hydrogenation and thermal cycling has been avoided. Furthermore, an innovative effective heating system of the membrane has been also applied.

Effects of H2O and H2O2 on Thermal Desorption of Tritium from Stainless Steel

Tritiated stainless steel was subjected to thermal desorption at various temperatures, different temperature profiles, and in the presence of different helium carrier gas additives. In all cases the identities of the desorbing tritiated species were characterized as either watersoluble or insoluble. The samples were found to contain 1.1 mCi±0.4 mCi. Approximately ninety-five percent of this activity was released in molecular water-soluble form. Additives of H2O or H2O2 to dry helium carrier gas increase the desorption rate and lower the maximum temperature to which the sample must be heated, in order to remove the bulk of the tritium. The measurements validate a method of decontamination of tritiated steel and suggest a technique that can be used to further explore the mechanisms of desorption from tritiated metals.

Interaction of Tritium with Oils and Tritiated Waste Oil Decontamination

Mineral and synthetic oils used as lubricants or operating fluids in pumps are mixtures of branched or cyclic saturated hydrocarbons. They are chemically inert but their slow partial oxidation is possible even at room temperature. Specific activity of pump oils contacted with gaseous tritium for a long time may exceed 1013 Bq/kg.Studies of waste oils show that more than 90% of the radionuclide is bound with oxidation products. This selectivity is owned to predominant formation of quasifree tritons or 3HeT+ ions when one of the two nuclei in the T2 molecule decays. The sequence of ion-molecule triton transport reactions is the mechanism responsible for accumulation of tritium by oxidation products with higher proton affinity.The most effective technique of oil decontamination is adsorption of tritiated species by polar adsorbents (silica gels, zeolites). The detritiation degree for these adsorbents amounts to 95%. Then complete thermal oxidative destruction can be used to convert adsorbed organic compounds into CO2 and water. Thus, adsorption, thermal oxidation and adsorbent regeneration may be proposed as the technology of tritium recycling since HTO returns to the isotope separation system. As a result, the radiation danger related with storage of high activity waste oils can be significantly decreased.

Yeast Hsl7 (histone synthetic lethal 7) catalyses the in vitro formation of ω-N G-monomethylarginine in calf thymus histone H2A

The HSL7 (histone synthetic lethal 7) gene in the yeast Saccharomyces cerevisiae encodes a protein with close sequence similarity to the mammalian PRMT5 protein, a member of the class of protein arginine methyltransferases that catalyses the formation of omega-N(G)-monomethylarginine and symmetric omega-N(G),N'(G)-dimethylarginine residues in a number of methyl-accepting species. A full-length HSL7 construct was expressed as a FLAG-tagged protein in Saccharomyces cerevisiae. We found that FLAG-tagged Hsl7 effectively catalyses the transfer of methyl groups from S-adenosyl-[methyl-3H]-L-methionine to calf thymus histone H2A. When the acid-hydrolysed radiolabelled protein products were separated by high-resolution cation-exchange chromatography, we were able to detect one tritiated species that co-migrated with an omega-N(G)-monomethylarginine standard. No radioactivity was observed that co-migrated with either the asymmetric or symmetric dimethylated derivatives. In control experiments, no methylation of histone H2A was found with two mutant constructs of Hsl7. Surprisingly, FLAG-Hsl7 does not appear to effectively catalyse the in vitro methylation of a GST (glutathione S-transferase)-GAR [glycine- and arginine-rich human fibrillarin-(1-148) peptide] fusion protein or bovine brain myelin basic protein, both good methyl-accepting substrates for the human homologue PRMT5. Additionally, FLAG-Hsl7 demonstrates no activity on purified calf thymus histones H1, H2B, H3 or H4. GST-Rmt1, the GST-fusion protein of the major yeast protein arginine methyltransferase, was also found to methylate calf thymus histone H2A. Although we detected Rmt1-dependent arginine methylation in vivo in purified yeast histones H2A, H2B, H3 and H4, we found no evidence for Hsl7-dependent methylation of endogenous yeast histones. The physiological substrates of the Hsl7 enzyme remain to be identified.

PRMT7 Is a Member of the Protein Arginine Methyltransferase Family with a Distinct Substrate Specificity

We have identified a mammalian arginine N-methyltransferase, PRMT7, that can catalyze the formation of omega-NG-monomethylarginine in peptides. This protein is encoded by a gene on human chromosome 16q22.1 (human locus AK001502). We expressed a full-length human cDNA construct in Escherichia coli as a glutathione S-transferase (GST) fusion protein. We found that GST-tagged PRMT7 catalyzes the S-adenosyl-[methyl-3H]-l-methionine-dependent methylation of the synthetic peptide GGPGGRGGPGG-NH2 (R1). The radiolabeled peptide was purified by high-pressure liquid chromatography and acid hydrolyzed to free amino acids. When the hydrolyzed products were separated by high-resolution cation-exchange chromatography, we were able to detect one tritiated species which co-migrated with an omega-NG-monomethylarginine standard. Surprisingly, GST-PRMT7 was not able to catalyze the in vitro methylation of a GST-fibrillarin (amino acids 1-148) fusion protein (GST-GAR), a methyl-accepting substrate for the previously characterized PRMT1, PRMT3, PRMT4, PRMT5, and PRMT6 enzymes. Nor was it able to methylate myelin basic protein or histone H2A, in vitro substrates of PRMT5. This specificity distinguishes PRMT7 from all of the other known arginine methyltransferases. An additional unique feature of PRMT7 is that it seems to have arisen from a gene duplication event and contains two putative AdoMet-binding motifs. To see if both motifs were necessary for activity, each putative domain was expressed as a GST-fusion and tested for activity with peptides R1 and R2 (acetyl-GGRGG-NH2). These truncated proteins were enzymatically inactive, suggesting that both domains are required for functionality.

Tritium Inventories in the High Vacuum Pumps of ITER

ABSTRACTThe tritium inventory of an experimental fusion reactor like ITER is determined by a broad range of influential factors. The tritium retention in the vacuum system is one important contribution to the overall tritium inventory. The high vacuum system for ITER is based on a set of cryogenic pumps, and sees the whole spectrum of tritiated gas species. The cryopumps are accumulation pumps; thus, the semi-permanent tritium inventory present in them is governed by the effectiveness of pump regeneration. Moreover, a permanent inventory background must also be envisaged. This paper delineates the staggered pump concept and a multi-stage regeneration scheme as main measures for step-wise minimisation of the tritium inventory in the high vacuum pump system and outlines the different contributions which add to it. By these methods, the 268 g of tritium inventory present after nominal long pulse operation of ITER, depending on the chosen fuelling case, can be reduced to 6 g in the pumps themselves, plus up to 100 g of codeposited tritium needing recovery clean-up.

PRMT5 (Janus Kinase-binding Protein 1) Catalyzes the Formation of Symmetric Dimethylarginine Residues in Proteins

We have identified a new mammalian protein arginine N-methyltransferase, PRMT5, formerly designated Janus kinase-binding protein 1, that can catalyze the formation of omega-N(G)-monomethylarginine and symmetric omega-N(G),N(G')-dimethylarginine in a variety of proteins. A hemagglutinin peptide-tagged PRMT5 complex purified from human HeLa cells catalyzes the S-adenosyl-l-[methyl-(3)H]methionine-dependent in vitro methylation of myelin basic protein. When the radiolabeled myelin basic protein was acid-hydrolyzed to free amino acids, and the products were separated by high-resolution cation exchange chromatography, we were able to detect two tritiated species. One species co-migrated with a omega-N(G)-monomethylarginine standard, and the other co-chromatographed with a symmetric omega-N(G),N(G')-dimethylarginine standard. Upon base treatment, this second species formed methylamine, a breakdown product characteristic of symmetric omega-N(G),N(G')-dimethylarginine. Further analysis of these two species by thin layer chromatography confirmed their identification as omega-N(G)-monomethylarginine and symmetric omega-N(G),N(G')-dimethylarginine. The hemagglutinin-PRMT5 complex was also able to monomethylate and symmetrically dimethylate bovine histone H2A and a glutathione S-transferase-fibrillarin (amino acids 1-148) fusion protein (glutathione S-transferase-GAR). A mutation introduced into the S-adenosyl-l-methionine-binding motif I of a myc-tagged PRMT5 construct in COS-1 cells led to a near complete loss of observed enzymatic activity. PRMT5 is the first example of a catalytic chain for a type II protein arginine N-methyltransferase that can result in the formation of symmetric dimethylarginine residues as observed previously in myelin basic protein, Sm small nuclear ribonucleoproteins, and other polypeptides.

Dosimetric implications of atmospheric dispersal of tritium near a heavy-water research reactor facility.

An estimate of the tritium dose to the public in the vicinity of the heavy water research reactor facility at AECL-Chalk River Laboratories, Ontario, Canada, has largely been accomplished from analyses on regularly-collected samples of air, precipitation, drinking water and foodstuffs (pasture, fruit, vegetables and milk) and environmental dose models. To increase the confidence with which public doses are calculated, tritium doses were estimated directly from the ratio of tritiated species in urine samples from members of the general public. Single cumulative 24 h urine samples from a few adults living in the vicinity of the heavy-water research reactor facility at Chalk River Laboratories, Canada were collected and analysed for tritiated water and organically bound tritium. The participants were from Ottawa (200 km east), Deep River (10 km west) and Chalk River Laboratories. Tritiated water concentrations in urine ranged from 6.5 Bq.l-1 for the Ottawa resident to 15.9 Bq.l-1 for the Deep River resident, and were comparable to the ambient levels of tritium-in-precipitation at their locations. The ultra-low levels of organically bound tritium in urine from these same individuals were measured by 3He-ingrowth mass spectrometry and were 0.06 Bq.l-1 (Ottawa) and 0.29 Bq.l-1 (Deep River). For Chalk River Laboratories workers, tritiated water concentrations in urine ranged from 32 Bq.l-1 to 9.2 x 10(4) Bq.l-1, depending on the ambient levels of tritium in their workplace. The organically bound tritium concentrations in urine from the same workers were between 0.08 Bq.l-1 and 350 Bq.l-1. With a model based on the ratio of tritiated water to organically bound tritium in urine, the estimated dose arising from organically bound tritium in the body for the Ottawa and Deep River residents was about 26% and 50%, respectively, of the body water tritium dose. The workers in a reactor building at Chalk River Laboratories had less than 10% dose contribution from organically bound tritium, but had higher overall tritium dose due to frequent intakes of tritiated water vapour in the workplace. The results of this study suggest that most of the tritium dose to workers at Chalk River and general population near Chalk River is the result of tritiated water intakes and not due to dietary intake of organically bound tritium.

Dose contribution from metabolized organically bound tritium after chronic tritiated water intakes in humans.

Our earlier study of acute tritiated water intakes in humans has demonstrated that the dose contribution from metabolized organically bound tritium is less than 10% of the body water dose. To further demonstrate that the dose contribution from the organically bound tritium per unit intake of tritiated water is the same, regardless of whether the intake is acute (all at once) or chronic (spread over time), urine samples from six male radiation workers with chronic tritiated water intakes were collected and analyzed for tritium. These workers have a well-documented dose history and a well-controlled tritium bioassay database, providing assurance that their tritium intakes were in the form of tritiated water. Each month for a full calendar year, urine samples were collected from each exposed worker. The monthly concentration of tritiumin-urine for each exposed worker was no lower than 10(4) Bq L(-1) but no higher than 10(5) Bq L(-1). These urine samples were analyzed for tritiated water and organically bound tritium to determine the ratio of these tritiated species in urine. The average ratio of tritiated water to organically bound tritium in urine for each exposed worker was 330 +/- 129 (range, 297-589). In calculating the dose to these workers, we assumed that, under steady-state conditions, the ratio of the specific activity of tritium (3H activity per gH) in the organic matter and water fractions of urine is representative of the ratio of the specific activity of tritium in the organic matter and water fractions of soft tissue. A mathematical model was developed and used to estimate the dose increase from the metabolized organically bound tritium based on the ratio of tritiated water to organically bound tritium in urine. The resulting average dose from the organically bound tritium was 6.9 +/- 3.1% (range, 4.7-9.9%) of the body water dose for the six male workers, and agrees well with the value obtained from our acute tritiated water intakes study in humans. The observed dose contribution from organically bound tritium, relative to body water dose, is in agreement with current recommendations of assigning 10% of total body water dose for organically bound tritium in soft tissues after tritiated water intakes.

Corrosion des aciers et superalliages inoxydables en eau tritiée ‐ influence du tritium et des espèces radiolytiques

AbstractTo better understand the phenomena in metl equipment corrosion in tritiated water, a study of the behavior of oxide layers on a cobalt‐based stainless superalloy was made in this highly radioactive medium. The oxide characteristics are modified from the corrosion potential, in passivity and up to teh passivity and transpassivity limits. The corrosion of oxide sublayers, as exfoliation of the oxide, was shown. This would appear to be due to diffusion of tritiated species in the oxide. These species accumulate at the oxide‐alloy interface, thus modifying the number of charge carriers in te oxide.

Tritiated Waste Management - Tritiated Oil Packaging and Decontamination

Tritium Handling facilities often have oil lubricated vacuum pumps in active portions of tritium systems. The interaction of tritium with the oil can lead to the formation of various classes of tritiated species, both volatile and non-volatile. These tritiated species can cause problemats in terms of handling, dosimetry and ultimate waste disposal. Knowledge of these species and their relative concentrations will allow the safe and cost effective use of oil-filled pumps in tritium environments. In order to understand more accurately the specific dosimetry hazards, improve handling procedures and minimize waste volumes, the distribution of tritium amongst the several classes of tritiated species was determined. The change in tritium content and distribution over time was also determined.