The off-gas from the reprocessing of HTGR fuel elements is unique among reprocessing nuclear fuel reprocessing off-gases because of the large amount of CO produced by the burning of the fuel element which contains about ten times 4* as much graphite as heavy metals. The relatively high temperature of the burning process (i>800°C) releases virtually all of the volatile fission proist£* ducts« and troublesome amounts of some which are normally solid. There filters to remove particulate solids and sorbtion methods for I and HO which have good potential for application to this off-gas, but no existing technology was found to remove and concentrate the Kr. The high concentration of CO in the filtered gas stream (^90% CO , 10% light gases, 10-20 ppm Kr), and the similarity of CO behavior to that of Kr preclude the use of commonly employed processes such as membrane permeation, sorption on charcoal or molecular sieves, and physical absorption by a third component. The removal of CO 2 before such an operation appears feasible, but undesirable. A process involving Kr absorption in liquid CO. (KALC), which exploits the fact that Kr is more soluble in liquid CO than.is O , N , or CO, appears to be a natural solution to this particular problem.The solubility of Kr in liquid CO_ has been experimentally determined by 85 an ill situ radioactive counting method using Kr. This method avoided the problems usually associated with sampling systems of highly volatile components.Kr (a total content of about 100 ppm) and CO ? were contained in a sealed stainless steel tube, brought to equilibrium by rocking in a constant temperature bath, and counted with the tube in a vertical position to measure the radioactivity in each phase. DISTRIBUTION Of THIS DOCUMENT IS UNLIMITEEngineering calculations, based on literature values for the solubility of 0_, N_, and CO and the measured values for Kr, on a KALC system which employs a fractionator and a stripper as well as an absorber indicate that a decontamination factor for Kr of 1000 can be achieved and that the Kr can be concentrated such that it comprises several percent of the removal stream.Die Rare Gas Removal Pilot Plant at the ORGDP was used to explore the feasibility of operating a KALC system. In addition to demonstrating that feasibility, the initial pilot campaign provided encouragement that the KALC process will be a good way to decontaminate the HTGR reprocessing off-gases. DECONTAMINATION OF HTGR REPROCESSING OFF-GASES*M. E. Whatley, R. W. Glass, P. A. Haas, A. B. Meservey, and K. J. NotzOak Ridge National Laboratory Oak Ridge, Tennessee Off-gas from the reprocessing of HTGR fuel elements is unique among the processing plant off-gases because the graphite and other carbon components of the HTGR fuel must be burned. This means that the quantity of gas is larger than that evolved from LWR, or LMFBR processing and the composition is different since it is mostly C0 ? . While alternative processing schemes were suggested which proposed the separation of the graphite by physic...

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Co-precipitation methods are attractive for the preparation of mixed tkia-urania sols, as possible alternates to solvenf extraction methods. Excepttonally stable sols (>I8 mo.) resulted from the coprecipitation of thorium and U(IV) hydroxides in Th/U ratios of 1/1 and 3,5/1. Satisfactory microspheres were formed and calcined from one of these sols. A new co-precipitation method was developed for preparing 3 Th/l U mole ratio sols using hexavalent uranium, featuring the attainment of low nitrate-to-metal ratios by a "seed sol " techniqw, The sols readily formed noncracking microspheres i n 2-ethyl-1-hexanol by the conventional ORNL method and were fired to 99.5% of theoretical density and less than 1% porosity. MOTlCEThis document contains information of a preliminary nature and was preporad primarily for internal use at the Oak Ridge Notional Laboratory. It is subject to revision or comction and therefore dew not reprerent a find report.