Thermal Conductivity of Composites of Beryllia and Lithium Titanate
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JMEPEG DOI: 10.1007/s11665-013-0606-z
Thermal Conductivity of Composites of Beryllia and Lithium Titanate B.N. Rath, S.J. Ghanwat, Santu Kaity, Chandan Danani, R.V. Kulkarni, V.D. Alur, D. Sathiyamoorthy, and S. Anantharaman (Submitted October 1, 2012; in revised form May 8, 2013) The International Thermonuclear Experimental Reactor (ITER) is designed to demonstrate the scientific and technological feasibility of fusion power for energy purposes. Wide varieties of solid breeders and multiplier materials have been proposed for fusion blankets. Beryllium and lithium titanate (Li2TiO3) have been accepted as neutron multiplier and breeder materials, respectively. However, swelling of beryllium due to helium and tritium permeation through metallic beryllium and low thermal conductivity of lithium titanate have caused serious limitations when ITER is in the demo version. It has been well established that BeO due its highest thermal conductivity among the known ceramics, low neutron absorption cross section, and high neutron reflection cross section is a good neutron multiplier. In the present investigation, a novel ceramic single compound of BeO-Li2TiO3 was synthesized, keeping the BeO content to Li2TiO3 in the volume ratio of 80:20, 75:25, 65:35, and 55:45 with the aim of maintaining the tritium breeding ratio as more than one, and characterized for phases present by x-ray diffraction and scanning electron microscopy.
Keywords
beryllium oxide, composite, ITER, lithium titanate, neutron breeder, neutron multiplier, tritium breeding ratio
1. Introduction Thermal conductivity is an important physical property which is required in modeling heat transfer through solids and structures. The primary functions of a fusion reactor blanket are to breed sufficient tritium and to maximize the blanket heat deposition per deuterium-tritium (D-T) fusion neutron (Ref 1). Higher thermal conductivity of the blanket is desired as it will increase the heat extraction efficiency. Among the candidate materials for tritium breeding, lithium titanate (Li2TiO3) is one of the best materials because of many advantages like reasonable lithium atom density, low activation, excellent tritium release characteristics at low temperature, and compatibility with structural material (Ref 2). Beryllium is chosen as the neutron multiplier by many countries to increase the neutron population inside the reactor. Also, Beryllium oxide due to its high thermal conductivity, low neutron capture cross section, good strength, low neutron moderation, and an appreciable fast neutron multiplication factor due to the (n, 2n) reaction (Ref 3) and good compatibility with SS316LN is a good choice for neutron multiplier material. By mixing beryllium oxide with lithium titanate in the proper ratio,
thermal conductivity of the blanket can be increased without any significant change in tritium generation and neutron multiplication. However, no experimental results or theoretical data on the properties of mixed BeO-Li2TiO3 composite are available for a breeder-multiplier system.
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