Tritium Isotope Separation Research Articles

Tritium separation from radioactive wastewater by hydrogen isotope-selective exchange of hydrogen-bonded fluorine

The separation of tritium (3H) from radioactive wastewater is a persistent challenging problem in the nuclear industry from an environmental perspective. This study provides new insight into the tritium separation by investigating hydrogen isotope-selective exchange reaction on hydrogen-bonded fluorine (F····H····O) site. In this study, fluorinated mesoporous silica, F-MCM-41_NCs were prepared as a novel tritium sorbent that showed a significantly enhanced tritium isotope separation factor (α) compared to the pristine MCM-41 (α = 1.2). The optimal α of 3.3 is achieved using 0.5F-MCM-41_NC prepared with 0.5 g of NH4F per gram of MCM-41. This optimal α is attributed to an excellent compromise between the amount and the stability of (NH4)2SiF6 on the pore channel with the integrity of the MCM-41 framework. Experimental, theoretical, and analytical characterization results consistently support chemical affinity quantum sieving effect at F····H····O hydrogen-bonding sites via the hydrogen isotope-selective exchange reaction as the dominant tritiumseparation mechanism.

Optimization for the tritium isotope separation factor and permeation by selecting temperature and thickness of the diffusion Pd–Ag alloy cathode

Large quantities of tritiated water will be produced in the controlled fusion reactors for power generation. To eliminate the concentrated tritiated water and for recycling tritium, an industrial electrolyzer was developed. The aim of this paper is to give the design of this electrolyzer and the results for optimization in diffusion and in isotopic exchange by selecting thickness of a thimble-shaped Pd–25%Ag cathode working at high temperature and current. In this process, the tritium recovery system is based on the principle of the tritium diffusion Pd–Ag cathode which produces very pure hydrogen isotopes from enriched tritiated water.

Tritium Removal and Separation Technology Developments

Recent increased interest from regulators and the public has led more organizations to consider the environmental impact and safety considerations of tritium handling. Examples include the significance of the tritium isotope separation system on ITER licensing, remediation of ground water from power utilities and government facilities and concerns of high tritium concentrations within operational CANDU reactors.GE Healthcare, formerly Amersham plc, has been producing tritium-labelled chemicals since the late 1940s. GE’s manufacturing site located near Cardiff, UK has installed a tritium waste treatment and enrichment facility to radically reduce tritium discharges to the environment. This facility employs a continuous processing plant that recovers tritium from a complex mixture of tritiated organic and aqueous waste compounds. Two isotope separation techniques are used to achieve a final pure tritium product, which is used in the manufacturing of labelled compounds.Building upon this experience, together with Special Separations Applications Inc. (SSAI), GE has developed a large-scale diffusion-based isotope separation process as an alternative to conventional cryogenic distillation. Having a tritium inventory an order of magnitude lower than conventional cryogenic distillation, this process is attractive for heavy water detritiation, applicable to single and multi-unit CANDU reactors and research reactors as well as fusion applications. Additionally, the new process has advantages of being cryogen-free, less complex, simple to operate and having improved conventional and radiological safety.

Hydrogen Isotope Separation by Plasma-Chemical Method

Deuterium transfer (exchange) reaction as shown in HDO+H2=H2O+HD was studied as a case similar to the tritium transfer reaction as shown in DTO+D2=D2O+DT, the first step in tritium isotope separation of the tritiated heavy water DTO. The transfer reaction was plasma-chemically catalyzed by allowing a gas mixture such as H2O/D2, D2O/H2, H2O/HDO/H2 or H2O/D2O/HDO/H2 to flow through an atmospheric pressure discharge zone formed in a reaction chamber, the inner temperature of which was maintained just above 100°C. The plasma-chemical reactions diagnosed by infrared and emission spectroscopy revealed that the mixture underwent instantaneous deuterium transfer reactions as it passed the zone. The effectiveness of the method was demonstrated by high deuterium transfer rate, high separation factor of the transfer and a possibility of miniaturizing the separation facility.

Hydrogen Isotope Separation by Plasma-Chemical Method

Deuterium transfer (exchange) reaction as shown in HDO+H2=H2O+HD was studied as a case similar to the tritium transfer reaction as shown in DTO+D2=D2O+DT, the first step in tritium isotope separation of the tritiated heavy water DTO. The transfer reaction was plasma-chemically catalyzed by allowing a gas mixture such as H2O/D2, D2O/H2, H2O/HDO/H2 or H2O/D2O/HDO/H2 to flow through an atmospheric pressure discharge zone formed in a reaction chamber, the inner temperature of which was maintained just above 100°C. The plasma-chemical reactions diagnosed by infrared and emission spectroscopy revealed that the mixture underwent instantaneous deuterium transfer reactions as it passed the zone. The effectiveness of the method was demonstrated by high deuterium transfer rate, high separation factor of the transfer and a possibility of miniaturizing the separation facility.

Tritium Isotope Separation by Water Distillation Column Packed with Silica-gel Beads

Tritium enrichment or depletion by water distillation was investigated using a glass column of 32 cm in height packed with silica-gel beads of 3.4mm in average diameter. The total separation factor of the silica-gel distillation column, αH-T—, was compared with those of an open column distillation tower and of a column packed with stainless-steel Dixon rings. Depletion of the tritium activity in the distillate was enhanced by isotopic exchange with water adsorbed on silica-gel beads that have a higher affinity for HTO than for H2O. The value of alphaH-T-1 of the silica-gel distillation column was about four times larger than that of a column without any packing and about two times larger than that of the Dixon-ring column. The improvement of αH-T by the silica-gel adsorbent indicated that the height of the distillation-adsorption column becomes shorter than that of the height of conventional distillation columns.

Tritium Isotope Separation by Water Distillation Column Packed with Silica-gel Beads

Tritium Isotope Separation by Water Distillation Column Packed with Silica-gel Beads

Dynamic Simulation of the ITER Fuel Cycle

This paper discusses a dynamic simulation developed for the ITER fuel cycle including vacuum pumping, fuel processing, fueling, pellet injection, tritium breeding blanket detritiation, fuel purification and isotope separation. The dynamic simulation model is used for calculating the unsteady-state flow of materials through the various fuel processing systems. since many of the systems have substantial hold-up times, and the ITER reactor burn and dwell cycle is periodic, a steady state model cannot provide a complete picture of system behavior. The dynamic model allows assessment of flowrates and minimum and maximum inventories under a wide range of dynamic conditions. This information is necessary for proper specification of system design requirements.

Selectivity enhancement in tritium isotope separation by multiple frequency multiple photon dissociation of the CTF3/CHF3 System

Isotope separation of tritium by multiple photon dissociation process in multiple frequency fields of a TEA-CO2 laser is reported for the first time. A ten-fold improvement in the bulk selectivity was obtained in 8.5 Torr CTF3/CHF3 in the presence of buffer gas at room temperature using 9R(8) to 9R(14) CO2 laser lines compared to single frequency excitation. Investigations of various process parameters such as exciting laser frequencies, pulse energy, sample and buffer gas pressure indicate that this is a promising technique for the separation of tritium.

Variable Stage-Number Model for Simulating Batch Operation of Water Distillation Column for Tritium Isotope Separation

Variable Stage-Number Model for Simulating Batch Operation of Water Distillation Column for Tritium Isotope Separation

Variable stage-number model for simulating batch operation of water distillation column for tritium isotope separation.

A batch distillation of tritiated water (10 nCi/cm3) has been performed in a packed column 1, 6 cm inner diameter × 100 cm high. Packings were Dixon rings made of SUS. Time variations of tritium activity were measured by changing vapor flow rate within the column, and then the separative performances, such as the separation factors and the separative power per unit charge, were obtained. The maximum values of the total separation factor and the separative power per unit charge were 1.45 and 2.0×10-2, respectively. The vapor flow rate from the reboiler decreases as the batch operation proceeds, so that a simulation with a fixed stage-number, the usual case, could not sufficiently predict the experimental values. We have therefore developed a simulation procedure where the number of hypothetical stages can be changed during the batch operation in order to predict the dynamic column behavior obtained from the experiments. The simulation result with the variable stage-number agreed with the experimental one.

Radio-Gas Chromatographic Measurement of Separation Factors in Laser Isotope Separation of Tritium

Abstract A new method is proposed for the evaluation of the separation factors in laser isotope separation of tritium using radio-gas chromatograph technique, when the radioactivity detection is severely affected by the quenching effect. It is shown mathematically that the overall efficiency of radioactivity measurement with a proportional counter (internal gas flow type) can be described as functions of the intrinsic detection efficiency and the shape of the elution curve. This mathematical treatment is shown to be useful for the experimental determination of the separation factors for the system of CF3CTBrF/CF3CHBrF which is an excellent working substance for tritium isotope separation.

A continuous reactor for laser-induced tritium isotope separation.

The design procedure and the operation performance of a new continuous photoreactor for laser-induced tritium isotope separation were studied experimentally. The investigation of the design procedure consists of the following three steps: (1) extraction of the parameters for dissociation characteristics from focused-beam batch irradiation experiments: (2) model modification in the vicinity of the critical fluence and (3) prediction of reactor performance as a function of externally controllable variables such as the pulse energy and the gas flow rate. The results of continuous reactor experiments under realistic operating conditions were found to agree with the predicted performance and a design method was established.

CO 2 laser isotope separation of tritium with heptafluoropropanes (CF 3CF 2CTF 2 and CF 3CTFCF 3

Tritium isotope separation was attempted by laser-induced multiphoton dissociation (MPD) of tritiated heptafluoropropanes CF 3CF 2CTF 2 ( n-C 3TF 7) and CF 3CTFCF 3 ( i-C 3TF 7) using a transversely excited atmospheric pressure CO 2 laser. The isotopically selective MPD of n-C 3TF 7 was expected at frequencies below the 10 μm region. The MPD spectrum of i-C 3TF 7 showed a maximum at about 1000 cm −1 where i-C 3HF 7 was almost transparent. The dissociation rate constant and isotopic selectivity were studied as a function of the sample pressure, the temperature and the irradiation geometry. The critical fluence for dissociation of i-C 3TF 7 was found to be as low as 9 J cm −2 at 10 R(30) (982.1 cm −1), which is lower than those for tritiated trifluoromethane (CTF 3) and pentafluoroethane (C 2TF 5). High isotopic selectivities exceeding 1400 were attained with i-C 3TF 7- iC 3HF 7 at 982.1 cm −1. An extremely large hydrogen isotope exchange rate was observed between i-C 3HF 7 and tritiated water. These results indicate that i-C 3TF 7 can be used as one of the most promising molecules for laser isotope separation of tritium.

Tritium isotope separation by CO2-laser irradiation at low temperatures

Tritium isotope separation by CO2-laser induced multiphoton dissociation of CTF3 is investigated. For the optimization of the performance of this working substance, trifluoromethane, the conditions to yield high-selectivity at high-operating pressure and low-critical fluence for complete dissociation are studied using our deconvolution procedure. The irradiation conditions are varied over the following ranges; wavenumber: 1052–1087 cm−1, gas temperature: 25°C to −78°C, CHF3 pressure: 5–205 Torr. The selectivities exceeding 104 are observed for 85–205 Torr CHF3 at −78°C by the irradiation at 1057 cm−1.

Tritium Isotope Separation by Multiphoton Dissociation of CF3CTCIF

Tritium Isotope Separation by Multiphoton Dissociation of CF₃CTCIF

Tritium isotope separation by multiphoton dissociation of CF3CTClF.

Click to increase image sizeClick to decrease image sizeKEYWORDS: laser isotope separationtritiumcarbon dioxide lasermultiphoton dissociation2-chloro1, 1, 1, 2-tetrafluoroethane

Tritium isotope separation by multiphoton dissociation of CTF3 under CO2-laser pulses

Isotopic separation of tritium by CO2 laser induced multiphoton dissociation of tritiated fluoroform is reported. It is found that maximum dissociation occurs around 1060 cm−1, that is close to the center of P branch of ν2 (CTF3). (AIP)

CO2 laser tritium isotope separation: Collisional effects in multiphoton dissociation of trifluoromethane

Multiphoton dissociation of ppm level CTF3 in CHF3 is reported. The effect of buffer gas pressure on the specific dissociation rates and the isotopic selectivity is investigated. Pulse energy dependence of the dissociation rates is converted to the intrinsic relation between the fractional conversion per pulse and the fluence by means of the new deconvolution technique. By addition of 100 Torr argon, the critical fluence of CTF3 was decreased from 136 to 34 J/cm2, while the intrinsic selectivity was increased from 34 to 580. In the absence of buffer gas argon, the fractional conversion per pulse exhibits two different pressure dependences. Unlike in the case below 15 Torr, the system shows strong pressure dependence and loss of the isotopic selectivity above 15 Torr. Possible application to the tritium removal process is also discussed.

Tritium Isotope Separation by CO2Laser Irradiation at Dry Ice Temperature

KEYWORDS: laser isotope separationtritiumcarbon dioxide lasermultiphoton dissociationtrifluoromethaneradio gas chromatographycryogenic isotope separationlow temperaturemedium pressure