Heavy water thermal conductivity

In a study conducted by the Armour Research Foundation (Ref 41) a-Pb azide crystals wrapped in a thin A1 foil were subjected to fast and thermal neutrons in the heavy water pile at Argonne National Laboratory. With a thermal flux rate of about 10l4n/cm2/sec the crystals were irradiated for 8, 17 and 170 hours. The crystals decompd to a brown powder which was identified as Pb carbonate by X-ray techniques and infrared absorption spectra. From a mass spectrographic analysis of the isotopes of carbon and oxygen in the decompn products, it was determined that the mechanism of carbonate formation is a reaction with the atmosphere by broken surface bands produced by the neutrons. Subsequently, Raney (Ref 60) reported... 

Many methods have been used to determine the deuterium content of hydrogen gas or water. For H2/D2 mixtures mass spectroscopy and thermal conductivity can be used together with gas chromatography (alumina activated with manganese chloride at 77 K). For heavy water the deuterium content can be determined by density measurements, refractive index change, or infrared spectroscopy. 

Uranium dioxide UO2 is the form in which uranium is most commonly used as a reactor fuel for light-water, heavy-water, and fast-breeder reactors. It is a stable ceramic that can be heated almost to its melting point, around 2760°C, without serious mechanical deterioration. It does not react with water, so that it is not affected by leakage of cladding in water-cooled reactors. Its principal disadvantages compared with uranium metal are its lower uranium atom density and lower thermal conductivity. At 100°C, thermal conductivities are metal, 0.25 UO2, 0.09 W/(cm-°C). 

Heat is deposited in the heavy water moderator contained within the calandria during normal operation, from direct gamma and neutron interaction and through thermal conduction from the fiiel channels. This heat is removed by the moderator cooling system, which circulates and cools the heavy water in an external circuit connected to the calandria the heat is rejected to the recirculated coolant water system. 

This treatise is an exhaustive compilation of physical data on heavy water (deuterium oxide). Some of the more relevant properties that are covered include densities, critical constants, vapor pressures, enthalpies of transition, viscosity, and thermal conductivity, equation of state, and tables of thermodynamic properties as functions of temperature and pressure. 

Example 6.2. A heavy-water-moderated reactor has fuel in the form of natural uranium metal rods of diameter 1 in., with cladding of 0.04-in. aluminum. The heat generation rate per unit volume of a fuel element at the center plane of the reactor is 1.85 x 10 Btu/h ft. The maximum fuel temperature is 690°F and the heat transfer coefficient to the coolant is 5500 Btu/h ft °F. If the thermal conductivities of uranium and aluminum are 18.5 Btu/h ft °F and 131 Btu/h ft F, respectively, calculate the bulk coolant temperature at the center plane. 

Viscosity and thermal conductivity of heavy water substance... 

The viscosity and thermal conductivity of heavy water and steam, the heavy water substance D2O, show trends which are similar to those of ordinary water substance. 

Formulations for general and sdentiflc use have also been adopted for other properties of water. The most industrially important of these are probably the viscosity and the thermal conductivity, although some other properties such as the static dielectric constant and the refractive index are important in research. There are also lAPWS formulations for some properties of heavy water (deuterium oxide, D2O). 

In order to limit thermal stresses and to reduce corrosion of the steel vessel, the reflector temperature was regulated near 350°F. About 50 kw of heat conducted from the fuel core to the reflector liquid was removed by circulating the heavy water with a 30-gpm canned-rotor pump through a reflector cooler which acted as a boiler feedwater preheater. A jet was located in this high-pressure circulating loop, the suction of which drew a continuous stream of gas from the vapor space above the reflector to a catalytic recombiner so that the concentration of deuterium and oxygen gases in this vapor space could be kept below explosive limits. 

Battery safety is so important for mobile and vehicle apphcations. Especially for vehicles, on the road, accident likely becomes heavy, and the crash accident should not bring more danger by release of the energy stored in the cells. And various tests are usually conducted. In ZEBRA battery case, test results were reported. Crash of an operative battery against a pole with 50 km/h, overcharge test, overdischarge test, short circuit test, vibration test, external fire test, and submersion of the battery in water have been specified and performed [6]. The ZEBRA battery did pass all these tests owing to its four-barrier safety concept [7, 8] chemical aspects, cell case, thermal structure, and battery controller. 

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