| DOI: | 10.2172/1045370
|
| 报告号: | LAB-RPT-12-00001
|
| 报告题名: | LABORATORY REPORT ON THE REDUCTION AND STABILIZATION (IMMOBILIZATION) OF PERTECHNETATE TO TECHNETIUM DIOXIDE USING TIN(II)APATITE |
| 作者: | DUNCAN JB; HAGERTY K; MOORE WP; RHODES RN; JOHNSON JM; MOORE RC
|
| 出版年: | 2012
|
| 发表日期: | 2012-06-01
|
| 总页数: | 23
|
| 国家: | 美国
|
| 语种: | 英语
|
| 中文主题词: | 磷
; 硝酸
; 氧
; PH
; 磷酸盐
; PH值
|
| 主题词: | PHOSPHORUS
; NITRIC ACID
; OXYGEN
; PH
; PHOSPHATE
|
| 英文摘要: | This effort is part of the technetium management initiative and provides data for the handling and disposition of technetium. To that end, the objective of this effort was to challenge tin(II)apatite (Sn(II)apatite) against double-shell tank 241-AN-105 simulant spiked with pertechnetate (TcO{sub 4}{sup -}). The Sn(II)apatite used in this effort was synthesized on site using a recipe developed at and provided by Sandia National Laboratories; the synthesis provides a high quality product while requiring minimal laboratory effort. The Sn(II)apatite reduces pertechnetate from the mobile +7 oxidation state to the non-mobile +4 oxidation state. It also sequesters the technetium and does not allow for re-oxidization to the mo bile +7 state under acidic or oxygenated conditions within the tested period oftime (6 weeks). Previous work (RPP-RPT-39195, Assessment of Technetium Leachability in Cement-Stabilized Basin 43 Groundwater Brine) indicated that the Sn(II)apatite can achieve an ANSI leachability index in Cast Stone of 12.8. The technetium distribution coefficient for Sn(II)apatite exhibits a direct correlation with the pH of the contaminated media. Table A shows Sn(II)apatite distribution coefficients as a function of pH. The asterisked numbers indicate that the lower detection limit of the analytical instrument was used to calculate the distribution coefficient as the concentration of technetium left in solution was less than the detection limit. The loaded sample (200 mg of Sn(II)apatite loaded with O.311 mg of Tc-99) was subjected to different molarities of nitric acid to determine if the Sn(II)apatite would release the sequestered technetium. The acid was allowed to contact for 1 minute with gentle shaking ('1st wash'); the aqueous solution was then filtered, and the filtrate was analyzed for Tc-99. Table B shows the results ofthe nitric acid exposure. Another portion of acid was added, shaken for a minute, and filtered ('2nd wash'). The technetium-loaded Sn(II)apatite was also subjected to water leach tests. The loaded sample (0.2 g of Sn(II)apatite was loaded with 0.342 mg of Tc-99) was placed in a 200-mL distilled water column and sparged with air. Samples were taken weekly over a 6-week period, and the dissolved oxygen ranged from 8.4 to 8.7 mg/L (average 8.5 mg/L); all samples recorded less than the detection limit of 0.01 mg/L Tc-99. The mechanism by which TcO{sub 2} is sequestered and hence protected from re-oxidation appears to be an exchange with phosphate in the apatite lattice, as the phosphorus that appeared in solution after reaction with technetium was essentially the same moles of technetium that were taken up by the Sn(II)apatite (Table 6). Overall, the reduction of the mobile pertechnetate (+7) to the less mobile technetium dioxide (+4) by Sn(II)apatite and subsequent sequestration of the technetium in the material indicates that Sn(II)apatite is an excellent candidate for long-term immobilization of technetium. The indications are that the Sn(II)apatite will lend itself to sequestering and inhibiting the reoxidation to the mobile pertechnetate species, thus keeping the radionuclide out of the environment. |
| URL: | http://www.osti.gov/scitech/servlets/purl/1045370
|
| Citation statistics: |
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| 资源类型: | 研究报告
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/40832
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| Appears in Collections: | 过去全球变化的重建
影响、适应和脆弱性
科学计划与规划
气候变化与战略
全球变化的国际研究计划
气候减缓与适应
气候变化事实与影响
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| Recommended Citation: | |
DUNCAN JB,HAGERTY K,MOORE WP,et al. LABORATORY REPORT ON THE REDUCTION AND STABILIZATION (IMMOBILIZATION) OF PERTECHNETATE TO TECHNETIUM DIOXIDE USING TIN(II)APATITE. 2012-01-01.
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