1988 Fiscal Year Final Research Report Summary
Chemical Behavior of Actinoids in Geological Formation
| Project/Area Number |
62580170
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Nuclear engineering
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
TOCHIYAMA Osamu Associate Professor, 工学部, 助講師 (70005479)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAZAKI Hiromichi Assistant, 工学部, 助手 (00166654)
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| Project Period (FY) |
1987 – 1988
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| Keywords | Actinoids / Migration in Geo- and Hydrosphere / Neptunium / Complex-Formation / Hydrous Oxide / Sorption / 収着機能 / 弱酸性イオン交換体 |
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| Research Abstract |
In order to assess the chemical behavior of actinoids, originating from radioactive wastes, in the hydrosphere and geosphere, distributions among varius oxidation states and chemical forms in the aqueous solution are estimated and their sorption behavior on amorphous hydrous metal (niobium and tin) oxides is investigated based on the proposed sorption model.
Among the actinoids, neptunium is the most mobile in the hydrosphere since its most stable oxidation state takes the least complex forming species NpO_2+ and its formation of water-soluble carbonato complexes supress the formation of insoluble hydroxieds. Since the complex formation constants of NpO_2+ closely correlate with those of UO_22+, it is to some degree degree possible to assess the environmental behavior or NpO_2+ from that of naturally occurring UO_22+.
Besides the behavior of actinoids in the homogeneous aqueous solutions, clarification of sorption mechanism of actinoids at solid-liquid interface is very important to understand their transport behavior in hydrosphere and geosphere. A proposed model based on the ion-exhange treatment on weakly acidic exchangers revealed that many transition metal and actinoid ions are sorbed through the formation of coordinated bond with hytoxyl groups of hyrous oxides while alkali and some alkali-earth metal ions are sorbed as free ions. Since the sorption of many metal inos depends on the specific bonding interactions, more detailed studies should be carried out on various naturally occurring sorbing materials.
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Research Products
(2 results)
