Evaluation of Gas-Graphite Suspensions as Nuclear Reactor Coolants. Final Report

ALL survey was made of experimental and theoretical work pertaining to the use of a suspension of graphite particles in a gas as a nuclear reactor coolant. Following a general review of the state-of-the-art and a detailed study of recent experimental data, it was concluded that present theoxy and experimental data are encouraging but inadequate as a basis for reactor design. Especially lacking are both theoretical and experimental work defining the hydrodynamic and thermal requirements for preventing the platingout of the solids from the suspension. Future work is recommended in which the stability of suspensions receives primary attention. Supporting parallel studies of basic theory, erosion, effects of nuclear radiations, and compatibility of materials, as well as development of specialized instrumentation and plant components, are also recommended. These would then be followed by experimental heat transfer and pressure drop studies to obtain correlations for reactor designm applications. (auth

The Elusive Structures of Pentakis [(triphenilphosphine)gold]ammonium(2+)Bis[tetraflouroborate(1-)]

{Pentakis[(triphenylphosphine)gold(I)]ammonium(2+)} bis[(tetrafluoroborate)(1-)] was prepared from {tetrakis-[(triphenylphosphine)gold(I)]-ammonium(1+)} [tetrafluoroborate(1-)] and [(triphenylphosphine)gold(I)] tetrafluoroborate in hexamethyl phosphoric triamide and tetrahydrofuran at 20 °C in 53% yield and crystallized from dichloromethane as the new solvate {[(Ph 3P)Au] 5N} 3 [BF 4] 6 [CH 2Cl 2] 4. The crystal structure of this product has been determined by single-crystal X-ray methods [monoclinic, P2 1/n, a = 34.200(3), b = 15.285(1), c = 53.127(3) Å, = 107.262(2)°, V = 26521(3) Å 3, Z = 12, at 153 K]. The lattice contains three independent trinuclear dications that have no crystallographically imposed symmetry and are mutually similar in their molecular structure. The geometry of the [Au 5N] core with pentacoordinate nitrogen atoms is intermediate between trigonal-bipyramidal and square pyramidal with severe distortions to minimize the Au-Au distances along some of the edges of the polyhedra. The three structures are thus different from that found previously in the tetrahydrofuran solvate {[(Ph 3P)-Au] 5N}(BF 4) 2(C 4H 8O) 2, where the geometry of the same trinuclear dication is closer to the trigonal-bipyramidal reference model. The new results are discussed in the light of the structures of tetra(gold)ammonium cations in salts of the type {[(Ph 3P)Au] 4N} +X - and of related tetra-, penta-, and hexacoordinate poly(gold)phosphonium, -arsonium, -sulfonium, and -selenonium cations