Solubility and speciation results from over- and undersaturation experiments on neptunium, plutonium, and americium in water from Yucca Mountain region well UE-25p {number_sign}1
Solubility and speciation results from over- and undersaturation experiments on neptunium, plutonium, and americium in water from Yucca Mountain region well UE-25p {number_sign}1
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DOI：
10.2172/171272
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发表时间：
1995-11
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通讯作者：
H. Nitsche;K. Roberts;K. Becraft;T. Prussin;D. Keeney;S. Carpenter;D. Hobart
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文献类型：
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作者：
H. Nitsche;K. Roberts;K. Becraft;T. Prussin;D. Keeney;S. Carpenter;D. Hobart
溶解度和形态对于了解水体放射性核素在地质圈中的传输非常重要。结果是通过在改良的 UE-25p-1 地下水（来自丝兰山地区， 内华达州，正在将其作为潜在的高放核废料处置场进行研究），温度为 60°C，三个 pH 值（6.0、7.0、8.5）。在过饱和实验中，确定了控制溶解度的稳态固体，并确定了上清液中存在的形态和/或氧化态。然后将表征的固体重新引入改良的 UE-25p-1 地下水的新鲜溶液中，以从欠饱和状态接近稳定状态。对于欠饱和实验，还鉴定了控制溶解度的稳态固体，并确定了上清液中存在的形态和/或氧化态。在过饱和和欠饱和实验中，Np 溶解度随着 pH 值的增加而降低。两个实验的稳态浓度在一个数量级内一致。在 pH 6 和 7 的实验中，过饱和和欠饱和的 Pu 浓度非常一致。 pH 8.5 过饱和实验产生的稳态浓度比欠饱和浓度高一个数量级。对于 Am/Nd 溶液，pH 6 和 pH 7 实验在过饱和和欠饱和条件下均产生了等效的稳态浓度。 pH 8.5 过饱和实验的溶解度是其欠饱和实验的 100 倍。 48 参考文献
Solubility and speciation are important in understanding aqueous radionuclide transport through the geosphere. Results are compared from solubility and speciation experiments from oversaturation and undersaturation of {sup 237}NpO{sub 2{sup +}}, {sup 239}Pu{sup 4+}, and {sup 241}Am{sup 3+}/Nd{sup 3+} in a modified UE-25p-1 groundwater (from the Yucca Mountain region, Nevada, which is being investigated as a potential high-level nuclear waste disposal site) at 60 C and three pH values (6.0, 7.0, 8.5). In the oversaturation experiments, the solubility-controlling steady-state solids were identified and the speciation and/or oxidation states present in the supernatant solutions were determined. The characterized solids were then reintroduced into fresh solutions of the modified UE-25p-1 groundwater to approach the steady state from undersaturation. For the undersaturation experiments, the solubility-controlling steady-state solids were also identified and the speciation and/or oxidation states present in the supernatant solutions were determined. The Np solubility decreased with increasing pH in both the over- and undersaturation experiments. The steady-state concentrations from the two experiments agreed to within an order of magnitude. Pu concentrations from over- and undersaturation agree very well in the pH 6 and 7 experiments. The pH 8.5 oversaturation experiment resulted in a steady-state concentration one order of magnitude above its undersaturation counterpart. For the Am/Nd solutions, the pH 6 and pH 7 experiments resulted in equivalent steady-state concentrations from both over and undersaturation. The pH 8.5 oversaturation experiment was 100 times more soluble than its undersaturation counterpart. 48 refs.