Preparation of Plutonium Hexafluoride. Recovery of Plutonium from Waste Dross; PREPARATION DE L'HEXAFLUORURE DE PLUTONIUM. RECUPERATION DU PLUTONIUM DES SCORIES D'ELABORATION
The influence of various physical factors on the rate of fluorination of solid plutonium tetrafluoride by fluorine was studied. In a horizontal oven with a circulation for pure fluorine at atmospheric pressure and 520#DEC, at a fluorine rate of 9 liters/hour, it is possible to transform 3 gm of tetrafluoride to hexafluoride with about 100% transformation and a recovery yield of over 90%, in 4 to 5 hours. The fluorination rate is a function of the temperature, the fluorine flow rate, the crucible surface, the depth of the tetrafluoride layer, and the reaction time. It does not depend on the diffusion of the fluorine into the solid but is determined by the reaction at the gas-solid interface and obeys the kinetic law (1 - T/sub T/)/sup 1/3/ = kt + 1. The existence of intermediate fluorides, in particular Pu/sub 4/ F/sub 17/, was confirmed by a break in the Arrhenius plot at about 370 deg C, by differences in the fluorination rates inside the tetrafluoride layer, and by reversible color changes. The transformation to hexafluoride occurs with a purification with respect to the foreign elements present in the initial plutonium. A study was made of plutonium recovery from waste based on the transformation of occluded plutonium particles to gaseous hexafluoride which is then decomposed thermally to the tetrafluoride which can be reintroduced directly in the production circuit. Under the conditions considered this process is not applicable industrially. After milling, it is possible to separate the dross into enriched (75% Pu in 2.6 wt. % of dross) and depleted portions. By prolonged fluorination (16 hrs) of the various fractions it is possible to recover about 80% of the plutonium. A treatment plant using fluidization should make it possible to substantially improve the yield. (auth)
- Research Organization:
- France. Commissariat a l'Energie Atomique. Centre d'Etudes Nucleaires, Saclay
- NSA Number:
- NSA-17-001555
- OSTI ID:
- 4774396
- Report Number(s):
- CEA-2161
- Country of Publication:
- France
- Language:
- English
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