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Title: Low temperature cold trapping of uranium hexafluoride containing hydrogen fluoride

Abstract

The use of a freezer-sublimer system operating at low desublimation pressures to replace 10-in. nuclearly safe cold traps for low assay (<5% U-235) uranium hexafluoride (UF{sub 6}) would significantly simplify operations and is economically attractive provided the nuclear safety of the system can be assured. A major requirement of such assurance is the availability of conditions guaranteeing that the nuclear safety design criterion, which requires that the H/U atomic ratio in the condensate in the freezer-sublimer always be less than 0.33 for assays up to 5%, will never be violated. A general vapor pressure equation giving the vapor pressure of HF-UF{sub 6} solutions as a function of temperature and mole fraction UF{sub 6} has been developed. The precision of the data at the 95% confidence level is {plus minus}0.1 torr at temperatures between {minus}100{degree}F and {minus}121{degree}F. The calculated vapor pressure of pure HF is 4.6 torr at {minus}100{degree}F and 3.1 torr at {minus}108{degree}F. Theoretical considerations suggest that the true value will be slightly lower. In experimental studies of the cold trapping operation at {minus}108{degree}F and at a trap pressure of 2.2 torr, only 7.3% of the HF entering the trap was retained in the trap. At a trap pressure ofmore » 4.6 torr, over 80% of the HF entering the trap was retained. The data obtained in this study confirms that the physical chemistry of the HF-UF{sub 6} system previously developed accurately describes the behavior of the system and that so long as the pressure in the trap is maintained below the vapor pressure of pure HF at the trap temperatures, there is no way that sufficient HF can be trapped to give an H/U ratio of 0.33 regardless of the HF/UF{sub 6} ratio in the feed to the trap. 5 refs., 4 tabs.« less

Authors:
; ;
Publication Date:
Research Org.:
Oak Ridge Gaseous Diffusion Plant, TN (USA)
Sponsoring Org.:
DOE/NE
OSTI Identifier:
6291490
Report Number(s):
K/ETO-37
ON: DE91005200
DOE Contract Number:  
AC05-84OT21400
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; COLD TRAPS; HYDROFLUORIC ACID; PHASE TRANSFORMATIONS; VAPOR CONDENSATION; URANIUM HEXAFLUORIDE; CHEMICAL REACTION KINETICS; ENRICHMENT; LOW TEMPERATURE; QUANTITATIVE CHEMICAL ANALYSIS; SAFETY; STATISTICAL DATA; STATISTICAL MECHANICS; STATISTICAL MODELS; VAPOR PRESSURE; VAPORIZATION HEAT; ACTINIDE COMPOUNDS; CHEMICAL ANALYSIS; CONDENSERS; DATA; ENTHALPY; FLUORIDES; FLUORINE COMPOUNDS; HALIDES; HALOGEN COMPOUNDS; HYDROGEN COMPOUNDS; INFORMATION; INORGANIC ACIDS; KINETICS; MATHEMATICAL MODELS; MECHANICS; NUMERICAL DATA; PHYSICAL PROPERTIES; REACTION KINETICS; THERMODYNAMIC PROPERTIES; TRANSITION HEAT; TRAPS; URANIUM COMPOUNDS; URANIUM FLUORIDES; VAPOR CONDENSERS; 050500* - Nuclear Fuels- Uranium Enrichment; 050700 - Nuclear Fuels- Fuels Production & Properties

Citation Formats

Hobbs, W.E., Barber, E.J., and Jones, C.G.. Low temperature cold trapping of uranium hexafluoride containing hydrogen fluoride. United States: N. p., 1990. Web. doi:10.2172/6291490.
Hobbs, W.E., Barber, E.J., & Jones, C.G.. Low temperature cold trapping of uranium hexafluoride containing hydrogen fluoride. United States. doi:10.2172/6291490.
Hobbs, W.E., Barber, E.J., and Jones, C.G.. Mon . "Low temperature cold trapping of uranium hexafluoride containing hydrogen fluoride". United States. doi:10.2172/6291490. https://www.osti.gov/servlets/purl/6291490.
@article{osti_6291490,
title = {Low temperature cold trapping of uranium hexafluoride containing hydrogen fluoride},
author = {Hobbs, W.E. and Barber, E.J. and Jones, C.G.},
abstractNote = {The use of a freezer-sublimer system operating at low desublimation pressures to replace 10-in. nuclearly safe cold traps for low assay (<5% U-235) uranium hexafluoride (UF{sub 6}) would significantly simplify operations and is economically attractive provided the nuclear safety of the system can be assured. A major requirement of such assurance is the availability of conditions guaranteeing that the nuclear safety design criterion, which requires that the H/U atomic ratio in the condensate in the freezer-sublimer always be less than 0.33 for assays up to 5%, will never be violated. A general vapor pressure equation giving the vapor pressure of HF-UF{sub 6} solutions as a function of temperature and mole fraction UF{sub 6} has been developed. The precision of the data at the 95% confidence level is {plus minus}0.1 torr at temperatures between {minus}100{degree}F and {minus}121{degree}F. The calculated vapor pressure of pure HF is 4.6 torr at {minus}100{degree}F and 3.1 torr at {minus}108{degree}F. Theoretical considerations suggest that the true value will be slightly lower. In experimental studies of the cold trapping operation at {minus}108{degree}F and at a trap pressure of 2.2 torr, only 7.3% of the HF entering the trap was retained in the trap. At a trap pressure of 4.6 torr, over 80% of the HF entering the trap was retained. The data obtained in this study confirms that the physical chemistry of the HF-UF{sub 6} system previously developed accurately describes the behavior of the system and that so long as the pressure in the trap is maintained below the vapor pressure of pure HF at the trap temperatures, there is no way that sufficient HF can be trapped to give an H/U ratio of 0.33 regardless of the HF/UF{sub 6} ratio in the feed to the trap. 5 refs., 4 tabs.},
doi = {10.2172/6291490},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1990},
month = {10}
}