The operating range for the reactor is between the minimum fluidization condition co' and co. Particles are lost if the rotational speed is less than co, and the bed is not fluidized if the rotational speed exceeds co The pressure drop across the bed remains about 1 psi. The temperature difference between the center of the fuel particle and its surface is calculated from Thus, exit gas temperatures in the range of 2000°K should be possible without danger of particles melting. Derivation of SPS configurations to utilize the above reactor concepts is given in section 5.0. where Nu = h Dp/kg. With e = 0.4 and Pr close to unity, h has a value of about 60,000 W/m2°K. 500 micron UO2 particles have a surface area of 1.09 m^/Kg. For a critical mass of uranium fuel of 1000 Kg, the total mass loading of UO2 particles in the reactor is 1137 Kg, with a total surface area of 1239 m^. The difference in temperature between the particle surface and the bulk gas is then REFERENCES 1) "Fluidized Carbon Coated Particles Reactor Concept," ERDA Contract No. E-(40-1 )-5273, Georgia Institute of Technology, Amt. S40,000, Duration Oct. 1, 1976-Dec. 31, 1976. 2) "Rotating Fluidized Bed Reactor for Space Nuclear Propulsion," Brookhaven National Laboratory Report BNL 50362, September 1972. 3) "Engineering Study of Cooloid Fueled Nuclear Rocket," Aerospace Research Laboratories Report No. 69-0234, prepared by Westinghouse Astronuclear Laboratory, December 1969. 4) "Analysis of UFg Breeder Reactor Power Plants," J. R. Williams. J. D. Clement and J. H. Rust, Georgia Tech, NASA Grant NSG-7067, November 1974. 5) "Fluidization and Fluid Particle Systems," Zenz and Othmer, Reinhold Publishing Corp., New York, 1960. 6) "Two Component Vortex Flow Studies, With Implications for the Colloid Core Nuclear Rocket Concept," L. A. Anderson, S. Hasinger and B. N. Turman, AIAA Paper No. 71-637. 7) Ted Mock, Garrett Corporation, private communication. 8) Wen, C. Y. and Yu, Y. H., "Mechanics of Fluidization," Chem. Eng. Progr. Symp. Ser., No. 67, Vol. 62, 100, (1966). 4.10 RADIATORS 4.10.1 Meteoroid Environment The fluid-loop thermal radiator design must consider meteoroid armoring requirements. Armoring places significant design constraints and mass penalties on the radiator. The average total meteoroid environment (average sporadic plus a derived stream) was derived using the flux-mass model described in Reference (1). The flux-mass environment is shown in Figure 4-39. A mass density of 0.5 gm/cm^ (.018 Ibm/ in^) was used for all meteoroid particle sizes.
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