Deuterium/tritium-containing

OtherApphca.tlons. Many appHcations of adsorption involving radioactive compounds simply parallel similar appHcations involving the same compounds in nonradio active forms, eg, radioactive carbon-14, or deuterium- or tritium-containing versions of CO2, H2O, hydrocarbons. For example, molecular sieve 2eohtes are commonly employed for these separations, just as for the corresponding nonradio active uses. 

The most plausible fusion reaction for producing energy commercially involves two isotopes of hydrogen, deuterium (D) and tritium (T), or H and H. Deuterium contains one proton and one neutron for an atomic number of two. Tritium contains one proton and two neutrons for an atomic number of three. The reaction is... 

Both deuterium and tritium have been used for tracer studies of hydrogen—that is, following the course of hydrogen through a chemical or biochemical reaction. However, the j3 ray given off from tritium is so very soft that its emission is difficult to detect with ordinary radiation counters (for which generally the instrument is placed near the sample) rather, the tritium-containing sample is often put -within the chamber of the instru-... 

For example, there are three distinct kinds of hydrogen atoms, commonly called hydrogen, deuterium, tritium. (This is the only element for which we give each isotope a different name.) Each contains one proton in the atomic nucleus. The predominant form of hydrogen contains no neutrons, but each deuterium atom contains one neutron and each tritium atom contains two neutrons in its nucleus (Table 5-2). All three forms of hydrogen display very similar chemical properties. 

Only a small amount deuterium is required to fuel a fusion reactor. Natural sources of hydrogen contain 0.0156% deuterium. A metric ton (1000-kg) of hydrogen from any source contains 156 grams of deuterium. Tritium is unknown in nature however, the neutrons produced by fusion react with lithium to produce tritium. There is sufficient deuterium and lithium to provide energy for thousands of years. 

Atoms of a given element do not all have the same mass. Most elements have two or more isotopes, atoms that have the same atomic number but different mass numbers. For example, there are three isotopes of hydrogen. One, simply known as hydrogen, has one proton and no neutrons. The deuterium isotope contains one proton and one neutron, and tritium has one proton and two neutrons. The accepted way to denote the atomic number and mass number of an atom of an element (X) is as follows ... 

Isotope effects on equilibria are generally smaller than isotope effects on rate and not so informative, but attention will be devoted to them for reactions involving hydrogen- vs deuterium-or tritium-containing molecules. These effects can have a marked influence on over-all rate when pre-equilibria involving proton transfers are part of the over-all reaction. 

Small cells are utilized to electrolyse deuterium or tritium containing water There are two applications for these cells (t) they may be operated in a similar fashion to conventional water clectrolysers but producing deuterium or tritium gas (in place of pure hydrogen) frorn DjO. DHO or HTO (2) (and more commonly) the cells may be used to concentrate the amount of deuterium or tritium in the electrolyte (DTO DHO HTO or DjO), This is made possible by kinetic factors which determine that hydrogen is evolved more rapidly than deuterium or tritium, e.g. hydrogen is evolved from 2 to 10 times faster than deuterium. The natural abundance of deuterium in water is very low (c. 150 mg dm" Hence, extensive electrolysis is required to produce a stgnih-cant level of heavy (dcutcriatcd) water. 

Pulsed plasmas containing hydrogen isotopes can produce bursts of alpha particles and neutrons as a consequence of nuclear reactions. The neutrons are useful for radiation-effects testing and for other materials research. A dense plasma focus filled with deuterium at low pressure has produced 10 neutrons in a single pulse (76) (see Deuterium AND TRITIUM). Intense neutron fluxes also are expected from thermonuclear fusion research devices employing either magnetic or inertial confinement. 

Thermodynamic Properties. Ordinary water contains three isotopes of hydrogen [1333-74-0] (qv), ie, H, H, and H, and three of oxygen [7782 4-7] (qv), ie, O, and The bulk of water is composed of and O. Tritium [15086-10-9] H, and are present only in extremely minute concentrations, but there is about 200-ppm deuterium [16873-17-9], H, and 1000-ppm in water and steam (see Deuterium and tritium). The thermodynamic properties of heavy water are subtly different from those of ordinary water. lAPWS has special formulations for heavy water. The properties given herein are for ordinary water having the usual mix of isotopes. 

Hydrogen as it occurs in nature is predominantly composed of atoms in which the nucleus is a single proton. In addition, terrestrial hydrogen contains about 0.0156% of deuterium atoms in which the nucleus also contains a neutron, and this is the reason for its variable atomic weight (p. 17). Addition of a second neutron induces instability and tritium is radioactive, emitting low-energy particles with a half-life of 12.33 y. Some characteristic properties of these 3 atoms are given in Table 3.1, and their implications for stable isotope studies, radioactive tracer studies, and nmr spectroscopy are obvious. 

The amino acid methionine is formed by a melhylation reaction of homo cysteine with iV-methyltetrahydrofolate. The stereochemistry of the reactior has been probed by carrying out the transformation using a donor with a "chiral methyl group" that contains protium (H), deuterium (D), and tritium (T isotopes of hydrogen. Does the methylation reaction occur with inversion oi retention of configuration ... 

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