Tritium physical properties

Tables 2,3, and 4 outline many of the physical and thermodynamic properties ofpara- and normal hydrogen in the sohd, hquid, and gaseous states, respectively. Extensive tabulations of all the thermodynamic and transport properties hsted in these tables from the triple point to 3000 K and at 0.01—100 MPa (1—14,500 psi) are available (5,39). Additional properties, including accommodation coefficients, thermal diffusivity, virial coefficients, index of refraction, Joule-Thorns on coefficients, Prandti numbers, vapor pressures, infrared absorption, and heat transfer and thermal transpiration parameters are also available (5,40). Thermodynamic properties for hydrogen at 300—20,000 K and 10 Pa to 10.4 MPa (lO " -103 atm) (41) and transport properties at 1,000—30,000 K and 0.1—3.0 MPa (1—30 atm) (42) have been compiled. Enthalpy—entropy tabulations for hydrogen over the range 3—100,000 K and 0.001—101.3 MPa (0.01—1000 atm) have been made (43). Many physical properties for the other isotopes of hydrogen (deuterium and tritium) have also been compiled (44).

Tritium is the subject of various reviews (6—8), and a book (9) provides a comprehensive survey of the preparation, properties, and uses of tritium compounds. Selected physical properties for molecular tritium, are given in Table 1. 

Properties of T2O. Some important physical properties of T2O are Hsted in Table 2. Tritium oxide [14940-65-9] can be prepared by catalytic oxidation of T2 or by reduction of copper oxide using tritium gas. T2O, even of low (2—19% T) isotopic abundance, undergoes radiation decomposition to form HT and O2. Decomposition continues, even at 77 K, when the water is fro2en. Pure tritiated water irradiates itself at the rate of 10 MGy/d (10 rad/d). A stationary concentration of tritium peroxide, T2O2, is always present (9). AH of these factors must be taken into account in evaluating the physical constants of a particular sample of T2O. 

Table 3.2 Physical properties of hydrogen, deuterium and tritium...

Because isotopes of the same element have the same number of protons and the same number of electrons, they have essentially the same chemical and physical properties. However, the mass differences between isotopes of hydrogen are comparable to the masses themselves, leading to noticeable differences in some physical properties and slight variations in some of their chemical properties. Hydrogen has three isotopes (Table B.2). The most common ( H) has no neutrons so its nucleus is a lone proton. The other two isotopes are less common but nevertheless so important in chemistry and nuclear physics that they are given special names and symbols. One isotope (2H) is called deuterium (D) and the other ( H) is called tritium (T). 

Isotopes of hydrogen. Three isotopes of hydrogen are known H, 2H (deuterium or D), 3H (tritium or T). Isotope effects are greater for hydrogen than for any other elements (and this may by a justification for the different names), but practically the chemical properties of H, D and T are nearly identical except in matters such as rates and equilibrium constants of reactions (see Tables 5.1a and 5.1b). Molecular H2 and D2 have two forms, ortho and para forms in which the nuclear spins are aligned or opposed, respectively. This results in very slight differences in bulk physical properties the two forms can be separated by gas chromatography. 

As tritium is used only in tracer proportions, only the physical properties of deuterated sugars (into which the deuterium is usually introduced at 100% abundance) are of interest. Many of these properties have been discussed in Section IV, as they are very useful for localizing the deuterium. 

The primary assumption is that radioactive isotopes are chemically identical with stable isotopes of the same element, i.e. the substitution of for in a conqxiund of carbon does not change the type or strmgth of the chemical bonds nor does it affect the physical properties of the compound. The validity of this assumption depends on the precision of measurement of the chemical and physical properties. The difference in mass between the various isotopes does cause some change in these properties ( 2.5) but even in the case of and with a mass differmce of approximately 15%, the isotope effect is rather small and difficult to detect. Normally only for systems involving hydrogen-deuterium-tritium substitution must isotope effects be considered. For heavier elements it can be neglected in almost every situation. 

Material is selected for various applications in a reactor facility based on its physical and chemical properties. This chapter discusses the physical properties of material Appendix A contains a discussion on the compatibility of tritium with various materials. 

Since 1952, most of the tritium measured in the atmosphere originates from thermonuclear explosions. Like hydrogen, deuterium and tritium also exhibit molecular isomerism. Because of the important differences between the relative atomic masses of the three isotopes, their physical properties (e.g., density, enthalpy of vaporization) differ greatly. This allows an easier isotopic separation than for any other element. Several separation processes are used for the enrichment and separation of hydrogen isotopes. Most of these processes use isotopic exchange reactions (e.g., H D-H O or NH3-HD) and to a lesser extent fractional distillation and water electrolysis (e.g., Norway, Canada). 

Neutron-physical parameters of the salt coolants make it possible to use them effectively both as neutron moderators and reflectors thermo-physical and neutron-physical properties of NaF-BeF2 salt are slightly worse than those of LiF-BeF2, but tritium production using this salt in the reactor is considerably smaller to improve the neutron balance and reduce the tritium production, the initial enrichment by Xi shall be at least 99.999%. 

The properties of tritium and carbon-14 are well suited for use as tracers in many life sciences and chemistry applications. Table 1.1 lists the important physical properties of the isotopes. 

Preparation of Compounds Labeled with Tritium and Carbon-14 Table 1.1 Physical properties of tritium and carbon-14... 

In addition to H2, D2, and molecular tritium [100028-17-8] the following isotopic mixtures exist HD [13983-20-5] HT [14885-60-0] and DT [14885-61-1]. Table 5 Hsts the vapor pressures of normal H2, D2, and T2 at the respective boiling points and triple points. As the molecular weight of the isotope increases, the triple point and boiling point temperatures also increase. Other physical constants also differ for the heavy isotopes. A 98% ortho—25/q deuterium mixture (the low temperature form) has the following critical properties = 1.650 MPa(16.28 atm), = 38.26 K, 17 = 60.3 cm/mol3... 

Electronically excited states of organic molecules, acid-base properties of, 12,131 Energetic tritium and carbon atoms, reactions of, with organic compounds, 2, 201 Enolisation of simple carbonyl compounds and related reactions, 18,1 Entropies of activation and mechanisms of reactions in solution, 1,1 Enzymatic catalysis, physical organic model systems and the problem of, 11, 1 Enzyme action, catalysis of micelles, membranes and other aqueous aggregates as models of, 17. 435... 

---