2012 Fiscal Year Final Research Report
Study on treatment and disposal form for used uranium catalyst for organic synthesis
| Project/Area Number |
21246143
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (A)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Nuclear engineering
|
|---|
| Research Institution | Nagoya University |
|---|
Principal Investigator |
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
SAWADA Kayo 名古屋大学, エコトピア科学研究所, 准教授 (90372531)
|
|---|
| Project Period (FY) |
2009 – 2012
|
| Keywords | 原子力化学工学 / ウラン廃棄物 / 超臨界流体抽出 / ガラス固化 / アンチモン / 塩化揮発 |
|---|
| Research Abstract |
For several decades, catalysts containing depleted U and Sb as a composite oxide were used for organic synthesis of acrylonitrile, and the spent catalysts are stored securely as uranium waste in Japan. A safe and economical disposal should be performed in the future. Unfortunately, however, uranium isotopes have long half lives to decay, and chemical and radioactive toxities of several daughter nuclides are too significant to dispose directly in a shallow land. We should take account of chemical toxity of antimony, too. Then we are proposing a method of decontaminating uranium and antimony and vitrifying the spent catalysts into a glass matrix by making use of the SiO2 supports of the catalyst. The goals of our study are recoveries of uranium and antimony with high yields from the tiny pores in sub-microns in diameter of SiO2 supports of the catalysts, and conditioning into a proper waste form for the shallow land disposal. In order to achieve these goals, treatment of the catalysts utilizing phase segregation phenomena of borosilicate glass was proposed and experimentally tested in a laboratory scale using a real specimen of the catalyst. The recovery yields achieved by the experiments were greater than 99.3% for uranium and 97.0% for antimony, and concentrations of uranium and antimony leached with de-ionized water for the final vitrified solids were below the detection limits by inductively coupled plasma spectrometer, 0.1 mg dm^<-3>.
|
