Dry process fluorination of uranium dioxide using ammonium bifluoride
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2003.
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | eng |
| Published: |
Massachusetts Institute of Technology
2010
|
| Subjects: | |
| Online Access: | http://hdl.handle.net/1721.1/58370 |
| _version_ | 1811069787711733760 |
|---|---|
| author | Yeamans, Charles Burnett, 1978- |
| author2 | Kenneth R. Czerwinski. |
| author_facet | Kenneth R. Czerwinski. Yeamans, Charles Burnett, 1978- |
| author_sort | Yeamans, Charles Burnett, 1978- |
| collection | MIT |
| description | Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2003. |
| first_indexed | 2024-09-23T08:16:08Z |
| format | Thesis |
| id | mit-1721.1/58370 |
| institution | Massachusetts Institute of Technology |
| language | eng |
| last_indexed | 2024-09-23T08:16:08Z |
| publishDate | 2010 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/583702022-01-26T16:34:53Z Dry process fluorination of uranium dioxide using ammonium bifluoride Yeamans, Charles Burnett, 1978- Kenneth R. Czerwinski. Massachusetts Institute of Technology. Dept. of Nuclear Engineering. Massachusetts Institute of Technology. Department of Nuclear Engineering Massachusetts Institute of Technology. Department of Nuclear Science and Engineering Nuclear Engineering. Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2003. Includes bibliographical references (p. 59-60). An experimental study was conducted to determine the practicality of various unit operations for fluorination of uranium dioxide. The objective was to prepare ammonium uranium fluoride double salts from uranium dioxide and ammonium bifluoride, then decompose these salts to uranium tetrafluoride through heating to temperatures near 425 °C in either a fluidized bed or a stirred bed. Fluorination in the stirred bed was attempted without pretreatment of the reagents. For the fluidized bed experiments, reagents were ball-milled prior to being heated in the bed. Experiments were conducted in either argon or 4% hydrogen in argon. The ball mill appeared to be an effective technique for fluorinating uranium dioxide with ammonium bifluoride. Samples changed color from brown to bright green, and no oxides could be detected in the x-ray diffraction pattern of the product. It was found that stainless steel is a suitable material of construction for reaction vessels, whereas mild steel parts corroded quickly. Only a small degree of fluidization provided adequate mixing in fluidized beds, but a paddle mixing the stirred beds left an unmixed region around the bed perimeter. Results from the stirred beds showed the initial fluorination reaction completed only when the reagents were heated to 110 °C for at least three hours under argon. Decomposition took place under argon with a temperature ramp up to 425 °C. The product UF4 contained less than 1% oxide as an impurity, and the decomposition appeared to be complete. Fluidized beds were run with both argon and 4% hydrogen in argon as carrier gases. Experiments with 4% hydrogen in argon produced uranium tetrafluoride, with ammonium uranium pentafluoride and uranium dioxide as impurties. Experiments in argon produced uranium tetrafluoride, with uranyl difluoride, ammonium diuranyl pentafluoride and triuranium octoxide as impurities. Minimum temperatures and times needed to decompose the double salt in the fluidized beds were 200 minutes at 115 °C, a 500-minute ramp to 425 °C, and 200 minutes at 425 °C. The intermediate double salt produced at 110 °C appeared to be triammonium uranium septafluoride. by Charles Burnett Yeamans. S.M. 2010-09-03T18:29:04Z 2010-09-03T18:29:04Z 2003 2003 Thesis http://hdl.handle.net/1721.1/58370 54977572 eng M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 86 p. application/pdf Massachusetts Institute of Technology |
| spellingShingle | Nuclear Engineering. Yeamans, Charles Burnett, 1978- Dry process fluorination of uranium dioxide using ammonium bifluoride |
| title | Dry process fluorination of uranium dioxide using ammonium bifluoride |
| title_full | Dry process fluorination of uranium dioxide using ammonium bifluoride |
| title_fullStr | Dry process fluorination of uranium dioxide using ammonium bifluoride |
| title_full_unstemmed | Dry process fluorination of uranium dioxide using ammonium bifluoride |
| title_short | Dry process fluorination of uranium dioxide using ammonium bifluoride |
| title_sort | dry process fluorination of uranium dioxide using ammonium bifluoride |
| topic | Nuclear Engineering. |
| url | http://hdl.handle.net/1721.1/58370 |
| work_keys_str_mv | AT yeamanscharlesburnett1978 dryprocessfluorinationofuraniumdioxideusingammoniumbifluoride |