Chemical Behavior of Transuranium Elements in Underground Environments

地下环境中超铀元素的化学行为

• 批准号: 63470137
• 负责人: TANAKA Satoru
• 金额: $ 2.94万
• 依托单位: University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1988
• 资助国家: 日本
• 起止时间: 1988 至 1989
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-63470137/
• 关键词: T R U; geological disposal; speciation; paper electrophoresis; ultrafiltration; colloid; adsorption; retardation; 限外ろ過法; 遠心分離; ネプツニウム; 溶解度; 熱力学データ; 口紙電気泳動法; 限外口過法; 酸化還元電位

Speciation, colloidal behavior, solubility/precipitation, and retardation phenomena of neptunium were experimentally studied. These are essential to clarify TRU migration in geologic media relating to safety assessment of high level radioactive wastes.1. Paper electrophoresis was found to be a useful method for studying speciation of the species which had opposite charge each other at low concentration and also for studying solubility of precipitate if the dissolved species had a charge. Using paper electrophoresis, hydrolysis constants for NpO_2OH^O and NpO_2(OH)^-_ were obtained. Solubility product of undissolved Np(IV) species was also obtained from experiments under anoxic conditions.2. Chemical behavior of neutral Np(V) species, under oxidizing conditions, and effects of coexisting SiO_2OH^O and Fe(III) colloids were studied using ultrafiltration and centrifugation; (1)NpO_2OH^O,NpO_2OH^O, and NpO_2OH^O+Fe(III) were partially trapped by ultrafiltration with the trappea fractions i … More ncreasing with respect to time. (2)Ultrafiltration trapped fractions were found to be higher than centrifuging precipitated fractions which indicates the possibility of adsorption onto the filter or the formation of small particles that were not centrifuged. (3)A Np-FE(III) pseudocolloid was formed and the trapped ratio was higher at increased Fe(III) concentrations.Under reducing conditions the chemical behavior of undissolved amorphous NpO_2.H_2O(am) was studied. Ultrafiltration was determined to be a difficult method to study the chemical behavior because of adsorption on the filter and the non-trapping of some undissolved species.3. From column experiments using quartz powder, the following conclusions were obtained; (1)The adsorption mechanism of NpO^+_ was made clear. NpO_2 is thought to be adsorbed electrostatically on the quartz surface. (2)Reiardation of NpO_2OH^O was found to be different from that of NpO^+_. Filtration of aggromeate was found to play an important role in the retention mechanism. In addition, sorption of NpO_2OH^O is also thought to be effective. (3)Retardation of megatively charged carbonate complexes was found to be little. (4)Neptunium(IV) undissolved species (NpO_2.xH_2O(am)) retarded in comparison with the Np(V) dissolved species, and the retardation factor increased with increasing pH and with decreasing particle size of quartz. Less

对镎的形态、胶体行为、溶解度/沉淀和延迟现象进行了实验研究。这些对于澄清与高放废物安全评估相关的地质介质中的 TRU 迁移至关重要。1．纸电泳被发现是一种有用的方法，可用于研究低浓度下彼此具有相反电荷的物质的形态，并且还可用于研究沉淀物的溶解度（如果溶解的物质具有电荷）。利用纸电泳，获得了NpO_2OH^O和NpO_2(OH)^-_的水解常数。缺氧条件下的实验还得到了未溶解的Np(IV)物质的溶解度乘积。 2．利用超滤和离心研究了氧化条件下中性 Np(V) 物质的化学行为以及共存 SiO_2OH^O 和 Fe(III) 胶体的影响； (1)NpO_2OH^O、NpO_2OH^O和NpO_2OH^O+Fe(III)被超滤部分截留，且陷阱分数随时间增加。 (2)发现超滤捕获的级分高于离心沉淀的级分，这表明有可能吸附到过滤器上或形成未离心的小颗粒。 (3)随着Fe(III)浓度的增加,形成了Np-FE(III)假胶体,且捕获率较高。研究了还原条件下不溶解的无定形NpO_2.H_2O(am)的化学行为。超滤由于过滤器上的吸附以及一些未溶解物质的不捕获而被认为是研究化学行为的一种困难方法。 3．通过使用石英粉的柱实验，得到以下结论： (1)明确了NpO^++的吸附机理。 NpO_2被认为是静电吸附在石英表面上的。 (2)发现NpO_2OH^O的反应与NpO^+_的反应不同。研究发现团聚物的过滤在保留机制中发挥着重要作用。此外，NpO_2OH^O的吸附也被认为是有效的。 (3)发现带大量电荷的碳酸盐配合物的延迟很小。 (4)镎(IV)未溶解物质(NpO_2.xH_2O(am))与Np(V)溶解物质相比具有延迟作用,并且延迟因子随着pH值的增加和石英颗粒尺寸的减小而增加。较少的

项目成果

S. Nagasaki, S. Tanaka and Y. Takahashi: "Speciation and Solubility of Neptunium in underground Environments by Paper Electrophoresis" Journal of Radioanalytical and Nuclear Chemistry, Articles, 124, 383-395 (1988).

S. Nagasaki、S. Tanaka 和 Y. Takahashi：“纸电泳在地下环境中镎的形态和溶解度”《放射分析与核化学杂志》，文章，124, 383-395 (1988)。

S.Tanaka: "Speciation and Retardation Phenomena of Neptunium in Underground Environments" Proceedings of the 1989 Joint International Waste Management Conference. 2. 375-382 (1989)

S.Tanaka：“地下环境中镎的形态形成和延迟现象”1989 年国际废物管理联合会议论文集。

S. Tanaka, S. Nagasaki, H. Itagaki and M. Yamawaki: "Speciation and Retardation Phenomena of Neptunium in Underground Environments" High Level Radioactive Waste and Spent Fuel Management (Proc. of the 1989 Joint International Waste Management Conference)

S. Tanaka、S. Nagasaki、H. Itagaki 和 M. Yamawaki：“地下环境中镎的形态和延迟现象”高放射性废物和乏燃料管理（1989 年国际废物管理联合会议议程）

S.,Tanaka: Proceedings of the 1989 Joint International Waste Management Conference. (1989)

S.,Tanaka：1989 年国际废物管理联合会议记录。

H.Itagaki,S.Tanaka,M.Yamawaki: "Neptunium Chemical Behavior in Underground Environments Using Ultrafiltration and Centrifugation" Proc.Migration '89(Radiochimica Acta.). (1990)

H.Itagaki、S.Tanaka、M.Yamawaki：“利用超滤和离心在地下环境中的镎化学行为”Proc.Migration 89（Radiochimica Acta.）。