DISCLAIMERPortions of this document may be illegible in electronic image products. Images are produced from the best available original document. SUMMARY. _ .When gaseous uranium h e x a f l u o r i d e ( U F 6 ) i s r e l e a s e d i n t o t h e atmosphere, i t r a p i d l y reacts w i t h ambient moisture t o form an a e r o s o l of u r a n y l f l u o r i d e ( U 0 2 F 2 ) and hydrogen f l u o r i d e ( H F ) .A s p a r t of o u r S a f e t y , A n a l y s i s program, w e have performed s e v e r a l e x p e r i m e n t a l releases of U F 6 i n c o n t a i n e d volumes i n o r d e r ' t o i n v e s t i g a t e t e c h n i q u e s f o r sampling and c h a r a c t e r i z i n g t h e a e r o s o l materials.The a g g r e g a t e part i c l e morphology and s i z e d i s t r i b u t i o n have been found t o be dependent upon s e v e r a l c o n d i t i o n s , i n c l u d i n g t h e temperature of t h e UF6 a t t h e t i m e of i t s release, t h e r e l a t i v e humidity of t h e a i r i n t o which i t is r e l e a s e d , and t h e e l a p s e d t i m e a f t e r t h e release. Aerosol composition and s e t t l i n g rate have been i n v e s t i g a t e d u s i n g s t a t i o n a r y samplers f o r t h e separate c o l l e c t i o n of U02F2 and HF and v i a laser spectroscopic remote s e n s i n g ( M i e scatter and i n f r a r e d s p e c t r o s c o p y ) .

No abstract

LJhen gaseous UF6 is released into the atmosphere, it rapidly reacts with ambient moisture to form an aerosol of uranyl fluoride and HF. As part of our Safety Analysis program, we have performed several experimental releases of UF (from natural uranium) in contained volumes in order to investigate techniques for sampling and characterizing the aerosol materials. The aggregate particle morphology and size distribution have been found to be dependent upon several conditions, including the relative humidity at the time of the release and the elapsed time after the release. Aerosol composition and settling rate have Seen investigated using isokinetic samplers for the separate collection of UO F and HF, and via laser spectroscopic remote sensing (Mie scatter and infraA2 spectroscopy). I UF6 (g) + 2 HzO (9) * U0f2 (S) + 4 HF (9) (1) DISTRIBUTION OF mils DOCMENT IS UNLIMITED

A series of experiments has been performed in which UF6 was released into flowing air in order to characterize the solid particulate material produced under non-static conditions. In two of the experiments, the aerosol was allowed to stagnate in, a static chamber after release and examined further but in the other experiments characterization was done only on material collected a few seconds after release. Transmission electron microscopy and mass measurement by cascaded impactor were used to characterize the aerosol particles which were usually single spheroids with little agglomeration in evidence.

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