Mixtures Of Hydrogen Isotopes Research Articles

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.

Muon catalysis and fusion reactions at low energies

Abstract The essence of the phenomenon of the muon catalysed fusion (μCF) is explained. The today status of the muon catalysis investigations is presented and various aspects of μ CF application are discussed. Muon catalysed fusion as a probe of few nucleon system structure is considered and the theoretical analysis of the methods to obtain the relevant information is presented. The kinetics of μ CF processes in the hydrogen isotope mixture is considered and the observables in μ CF are related to the characteristics of the fusion reactions between hydrogen isotopes. The perspectives and unsolved problems are outlined.

Early experiments of JAERI fuel cleanup system at the tritium systems test assembly

The Tritium Process Laboratory (TPL) at the Japan Atomic Energy Research Institute (JAERI) has developed a Fuel Cleanup System (FCU) which accepts simulated fusion reactor exhaust and produces pure hydrogen isotopes and tritium-free waste. Under the collaboration program of USDOE and JAERI, an integrated process, the “JAERI Fuel Cleanup System” (JFCU) was designed and fabricated for testing at the Tritium Systems Test Assembly (TSTA) as a major subsystem of the simulated fusion fuel cycle. The JFCU has the capability to continuously process a mixture of hydrogen isotopes and impurities of 15 mol/h. The major components are: a palladium diffuser for hydrogen isotopes purification, a catalytic reactor for oxidation of tritium in impurities, cold traps for separation of tritiated water to produce exhaust containing a very low level of tritium, a ceramic electrolysis cell for decomposition of tritiated water, and zirconium-cobalt beds for hydrogen isotopes storage. In early 1990, the JFCU was installed in the TSTA and preliminary testing without tritium was initiated. Components such as the palladium diffuser, cold traps, catalytic reactor, scroll pump and electrolysis cell were tested independently as well as in the integrated process tests.

Application of an omegatron type high resolution mass spectrometer for the analysis of mixtures of hydrogen and helium isotopes

Gaseous mixtures containing the hydrogen isotopes H 2, HD, HT, D 2, DT and T 2, together with the stable helium isotopes 3He and 4He, can be analyzed with an omegatron, also known as a cyclotron resonance type mass spectrometer. This instrument has sufficient resolution to separate all hydrogen/helium isotope ions, except 3He + and T +. Main advantages of the combination of an omegatron with an appropriate vacuum gauge as an instrument for quantitative analysis are seen in its extremely low sample requirement, very low memory effects, simple operation, comparatively small overall volume (fits in a conventional glove box), and relatively low price.

PC-fortran programs for muon reactivation calculations in muon-cataluzed fusion

The introduction of a μ - particle into a mixture of hydrogen isotopes brings about a repetitive cycle of processes leading to nuclear fusion and the release of energy. Sticking is one of the critical processes limiting the number of fusions induced by one muon during its lifetime. When the (αμ) + ion created with the energy E=3.46 MeV is slowed down in a dense DT mixture, the muon can be stripped (reactivated), thus allowing the muon to return to the catalytic cycle. The coupled differential equations describing the reaction process are solved using the computer code as documented by L.F. Shampine and M.K. Gordon [Computer Solution of Ordinary Differential Equations, the initial value problem (Freeman, San Francisco, 1975)].

The cryogenic diffusion pump and its implementation in a complete fusion reactor forevacuum system

A cryogenic diffusion pump has been developed and tested. It uses the main constituent of the fusion reactor exhaust gas, i.e., deuterium–tritium (D–T), as a working fluid in a diffusion pump operating at low temperature, to separate and compress the minor constituent 4He. Since a suitable tritium-handling facility was not available, a prototype was tested using mixtures of deuterium with 1%, 2%, and 4% helium. As the deuterium is pumped by cryocondensation at 4 K, the entrained helium is staying in the gas phase, is compressed, and leaves the pump outlet at pressures up to 80% of the total inlet pressure. Compression ratios of up to 80 (for 1% helium) and inlet pumping speeds ranging from 1 to 2 m3 s−1 have been measured for operating pressures between 3 and 10 Pa. Deuterium carry-over into the helium exhaust was below the detection limit of the equipment. A design is presented incorporating the cryogenic diffusion pump in a complete fusion reactor forevacuum system, including the separation of impurities from hydrogen isotope mixtures.

Key components of the JET Active Gas Handling System — experimental programme and test results

The JET Active Gas Handling System is designed to process mixtures of hydrogen isotopes, helium and impurities during the operation of the JET tokamak with deuterium/tritium plasmas. Elements of crucial importance for plant operation have been built as prototypes and tested. The results show that • - the separation of hydrogen mixtures from impurities in the elements of the cryogenic forevacuum system works to the low ppm levels; • - uranium beds with internal cooling are capable of high take-up rates of hydrogen (100% of capacity in ∼15 minutes); • - uranium and iron beds are capable of tritium recovery from tritiated water, ion beds are regenerable; • - all metal valves, actuators and pressure regulators designed to work in all-metal vacuum double containments meet the design requirements. Furthermore, new methods for the recirculation of hydrogen streams in a cryodistillation system and the detection of isotopic transitions in a preparative gas chromatogtraphy system are described. The present state of the JET AGHS is reported.

The Cryogenic Forevacuum System for the JET Active Gas Handling Plant

The Cryogenic Forevacuum System (CFV) of the JET Active Gas Handling System is designed to collect gas mixtures from the torus and injection systems. The CFV separates hydrogen isotope mixtures from helium and impurities and stores isotope mixtures for separation. All crucial process elements are located in all-metal secondary containments. Prototype test on accumulation panels have shown the capability of pumping hydrogen/helium/impurity mixtures.

Experimental Appratus for Cryogenic Hydrogen Isotope Separation Process in the Tritium Process Laboratory

An experimental apparatus for the developemnt of cryogenic hydrogen isotope separation system (ISS) was designed and fabricated at the Tritium Process Laboratory (TPL) in Japan Atomic Energy Research Institute (JAERI). This apparatus will serve to study the separation characteristics of hydrogen isotope mixture with 104 Ci of tritium. It consists of two distillation columns with isotopic equilibrators for H-D-T mixtures and can be operated with both single column distillation mode and two interlinked cascade modes. Installation of this system in a glovebox was completed by late January, 1988. Tests with tritium will start late 1988.

Experimental Apparatus for Thermal Diffusion Process in the Tritium Process Laboratory

At the Tritium Process Laboratory (TPL) in the Japan Atomic Energy Research Institute, the Thermal Diffusion process is applied to enrich and recover tritium diluted by the operation and experiments of the other apparatus installed in the gloveboxes. The apparatus is required to process 200-liter of hydrogen isotope mixture containing up to lg tritium by batch operation and enrich tritium to 90%. Preliminary studies were performed numerically as well as experimentally, and good agreement was obtained. Based on the results, the apparatus was designed. Major components are four 2.5m-high diffusion columns, reservoirs, pumps, active metal beds and a mass spectrometer. Whole apparatus was installed in the glovebox in the TPL by the end of 1987. The function of the apparatus was tested with H-D mixtures.

Determination of muonic helium x-ray yields after muon-catalyzed pd, dd, and dt fusion.

X-ray yields of the muonic helium (2-1) transition from $\ensuremath{\mu}$-catalyzed fusion have been measured for the first time in various mixtures of hydrogen isotopes. They were determined to be 0.032(4), 0.016(2), and 0.0019(5) for $\mathrm{pd}$, $\mathrm{dd}$, and $\mathrm{dt}$ fusion, respectively.

Thermally induced behavior of liquid mixtures of hydrogen isotopes inside a spherical inertial confinement fusion target

A theory is presented which is intended to explain thermally induced formation of uniform liquid layers of ternary mixtures of hydrogen isotopes inside a spherical inertial confinement fusion (ICF) target. The governing equations are the equations of stream function, modified vorticity, and energy, and the equations of conservation of the individual isotopic species. The equations for the diffusion fluxes of the species include both ordinary and thermal diffusions. These coupled equations are solved by a finite-difference method using upwind schemes and variable mesh. The results demonstrate the influence of the concentration- and temperature-induced surface tension gradients in creating the uniform liquid fuel layer inside an ICF target. Comparison of the present theory with the experimental data is made for targets filled, respectively, with D2 and mixtures of H2 and D2, producing good agreement in both cases.

A Simulation Study for Hydrogen Isotope Distillation Columns in the Tritium Breeding Blanket System of a Fusion Reactor

In the tritium breeding system for a fusion reactor, the addition of a large flow rate of hydrogen (H2) or deuterium (D2) to the helium purge gas is considered essential to avoid a large amount of tritium inventory. However, the tritium concentration in the hydrogen isotope mixture to be separated is reduced by two or three orders of magnitude by the addition. The effects of the drastic dilution of tritium by H2 or D2 on the isotope separation by cryogenic distillation are analyzed. The analysis is made under the conditions of the Japanese Fusion Engineering Reactor where the tritium production rate is 3 g/h.It is shown that the dilution requires a specific cascade in addition to the cascade in the mainstream fuel circulation system. The H2 addition is much more favorable than the D2 addition in terms of the cascade scale needed, tritium inventory within the cascade, and refrigeration capacity required. The dilution of tritium by H2 by two orders of magnitude requires a two-column cascade, and the tritium inventory and refrigeration capacity required are ∼8 g and 65 W, respectively. The dilution by three orders of magnitude requires a three-column cascade, and the values of the two parameters are ∼12 g and 630 W, respectively. In these cases, the tritium inventory and refrigeration capacity required for the cascade in the mainstream fuel circulation system are ∼70 g and 110 W, respectively. Thus, the dilution up to three orders of magnitude could pose no serious problem in the isotope separation.

Cryopumping Hydrogen Isotope Mixtures in MFTF-B With and Without Argon Adsorbent

Mixtures of hydrogen isotopes, primarily deuterium (D2), protium-deuterium (HD), and protium (H2) must be pumped by the vacuum system in the Mirror Fusion Test Facility at Lawrence Livermore Nation...

A low temperature distillation system for separating mixtures of protium deuterium, and tritium isotopes

A low temperature (24 K) distillation system for separating mixtures of hydrogen isotopes has been designed, fabricated, and delivered for use as the main component of the Hydrogen Isotope Separation System (HISS) at Mound. The HISS will handle feed mixtures of all six isotopic species of hydrogen (H2, HD, HT, D2, DT, T2) and will enrich the tritium while producing a stackable raffinate. Arther D. Little, Inc. (ADL) was the prime contractor for the distillation system. The design and fabrication techniques used for the HISS distillation system are similar to those used for previous stills which were also designed and built by ADL. The distillation system was tested with mixtures of protium and deuterium at the ADL shop. This system, as well as the feed, product, and raffinate handling systems are presently being installed at Mound where integrated testing is scheduled next calendar year.

Muon-catalysed fusion as a finite Markov process

By regarding muon catalysis of nuclear fusion in a mixture of hydrogen isotopes as a series of stochastic processes. Markov chain theory is used to derive several exact analytic equations relating the rates of the various reactions and the sticking coefficients for the fusion channels. These include expressions for the mean number of pd, dd, dt, tt and pt fusion per muon, the mean total number of fusions per muon and the muon cycling rate lambda c, which reduce to the corresponding well known expressions for catalysis in a deuterium-tritium mixture. Inclusion of the fusion reaction dd mu to p mu +t provides a particularly interesting complication, as this process gives rise to a catalysis cycle that may not return a free muon to the system. The application of Markov chain theory to more complex catalysis schemes, such as those including hyperfine states of the mesic atoms and mesic molecules, is considered briefly.

The latest ultrahigh vacuum technique...On cryopump.

Cryopump is one type of storage pumps and offers truly contamination free vacuum. Commercial cryopumps which are cooled by refrigerator have made remarkable development in the last ten years and become practical industrial tool, for instance, in the field of semiconductor manufacture. Cryopumps which are cooled by liquid helium have been used to pump large amount of hydrogen gas in high energy neutral beam injector of large plasma devices and their applicability to pumping system of fusion reactor which exhausts mixtures of hydrogen isotopes and helium gases is now under study.

Characteristics of the permeation of hydrogen-inert gas mixtures through a palladium alloy tube wall

A hydrogen window for the selective separation of hydrogen and deuterium in a gas stream permeating a palladium alloy tube wall was investigated. The palladium alloy used was Pd-20%Ag-5%Au and the tube was 100 mm long with an internal diameter of 1.44 mm. Permeabilities of hydrogen and deuterium were measured at 400 °C and atmospheric pressure using H 2-Ar and D 2-Ar mixtures. A similar permeation experiment was performed using an H 2-D 2-Ar mixture. The permeation data for the mixture agreed with the theoretical predictions made using the permeability values obtained from the H 2-Ar and D 2-Ar experiments. Hence it was established that the permeation rates of hydrogen isotope mixtures through a hydrogen window can be estimated by our equations.

Electrolytic hydrogen isotope separation factors within low voltage hydrogen transfer cells

Measurements are reported of the ratios of hydrogen to deuterium in gas mixtures of hydrogen isotopes outgassed from palladium electrodes which had been acting in 1:1 H 2SO 4: D 2SO 4 electrolytes, as both cathodes and anodes of hydrogen transfer cells in which the effective overall cell reaction was the transfer of hydrogen (deuterium) from one electrode to the other.

Performance of BNL‐TSTA compound cryopump

The Tritium Systems Test Assembly Vacuum Facility at Los Alamos Scientific Laboratory is intended to demonstrate realistic fuel supply and cleanup operations similar to those anticipated on fusion devices. The plasma exhaust gases are expected to be mixtures of helium and hydrogen isotopes which can be pumped most efficiently by cryopumping. A compound cryopump for on‐line operation at TSTA using cryocondensation for hydrogen isotopes and cryosorption for helium has been designed by BNL and fabricated by Janis Research. The details of this compound cryopump are described in this paper. The performance of the pump during the pre‐delivery testing at BNL, such as the heat load during operation and the pumping speed and pump capacity for helium and hydrogen, are also discussed in detail.