陶瓷固化体的浸出行为及其机理

doi:10.15541/jim20180374

摘要/Abstract

摘要：

高放废物(HLW)在深地质处置后, 其中的放射性核素有可能浸出并伴随地下水循环进入人类环境。这是固化体中放射性核素进入生物圈最可能的途径, 因此HLW固化体的化学稳定性是固化基材筛选的主要依据。陶瓷固化体作为第二代HLW固化体, 具有长程有序的特点, 相比玻璃固化体, 更容易定量表征, 这对于固化体浸出机理的研究有着重要的意义。然而陶瓷固化体的浸出机理与评价方法研究都处于起步阶段, 也缺乏被处置库接收的标准。为规范/建全陶瓷固化体化学稳定性评价方法, 认识放射性核素的浸出机制, 本文概述了核废物固化体化学稳定性研究方法、研究重点; 总结了相关陶瓷的水热蚀变研究现状, 分析了其中核素的浸出率; 探讨了影响因素及其影响方式; 最后归纳了目前提出的浸出机制以及存在的问题。

关键词: 化学稳定性, 固化体, 浸出机制, 综述

Abstract:

The radionuclides in high-level radioactive waste (HLW) forms may be leached out over geological time and enter the human environment with groundwater circulation after deep geological disposal. This is likely the potential way for radionuclides to enter the biosphere. Therefore, the long-term chemical durability of HLW waste forms is the key issue for selecting suitable waste forms. Ceramic waste forms, regarded as the second generation of HLW forms, are of long-range ordered structures, whose physical properties can be easily characterized quantitatively. It is of great importance and significance to study the leaching mechanism of ceramic waste forms. However, not only the studies of leach mechanisms, but also the evaluation methods of ceramic waste forms are in their infancy. There is also lack of the standards of ceramic waste forms received by the repository. The present paper summarizes the research methods and key points of chemical durability, reviews the research status of hydrothermal alteration of related ceramics, and analyzes the leaching rate of radionuclides. In addition, the paper also discusses the influencing factors and their influencing modes, and finally concludes the leaching mechanisms and existing problems.

Key words: chemical durability, waste form, leaching mechanism, review

中图分类号:

TL94

孙亚平, 王洪龙, 褚健, 王绪, 潘社奇, 张铭. 陶瓷固化体的浸出行为及其机理[J]. 无机材料学报, 2019, 34(5): 461-468.

Ya-Ping SUN, Hong-Long WANG, Jian CHU, Xu WANG, She-Qi PAN, Ming ZHANG. Leaching Behavior and Mechanism of Ceramic Waste Forms[J]. Journal of Inorganic Materials, 2019, 34(5): 461-468.

图/表 8

参考文献 48

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Parameters	Glass	Ceramic
Loading of waste/wt%	10-30	15-30
Density/(g·cm^-3)	2.5-2.8	3.0-5.8
Leach rate/(g·cm^-2·d^-1)	10^-4-10^-7	10^-6-10^-10
Anti-pressure ability	Low	High
Radiation tolerance/Gy	10^-9	~10^-9

Parameters	Glass	Ceramic
Loading of waste/wt%	10-30	15-30
Density/(g·cm^-3)	2.5-2.8	3.0-5.8
Leach rate/(g·cm^-2·d^-1)	10^-4-10^-7	10^-6-10^-10
Anti-pressure ability	Low	High
Radiation tolerance/Gy	10^-9	~10^-9

Mineral	Formula	Immobilized nuclide^a
Zircon	ZrSiO₄	An
Titanite	CaTiSiO₅	Ln, An
Apatite	Ca₅(PO₄)₃(OH, F, O)	U, Th, REE, I, Cs
Monazite	CePO₄	Ce, La, Eu, Gd, U, LREE
Xenotime	YPO₄	HREE
Pyrochlore	CaUTi₂O₇	Ln, An
Baddeleyite	ZrO₂	Ln, An
Perovskite	CaTiO₃	Sr, REE, Fe, Na, An
Zirconolite	CaZrTi₂O₇	Ln, An, Fe, Ni, Cr, Zr
Brannerite	UTi₂O₆	Ln, An
Rutile	TiO₂	Zr
Alkali Psilomelane	BaA1₂Ti₆O₁₆	Cs, Sr, Ba, Rb, A1

Mineral	Formula	Immobilized nuclide^a
Zircon	ZrSiO₄	An
Titanite	CaTiSiO₅	Ln, An
Apatite	Ca₅(PO₄)₃(OH, F, O)	U, Th, REE, I, Cs
Monazite	CePO₄	Ce, La, Eu, Gd, U, LREE
Xenotime	YPO₄	HREE
Pyrochlore	CaUTi₂O₇	Ln, An
Baddeleyite	ZrO₂	Ln, An
Perovskite	CaTiO₃	Sr, REE, Fe, Na, An
Zirconolite	CaZrTi₂O₇	Ln, An, Fe, Ni, Cr, Zr
Brannerite	UTi₂O₆	Ln, An
Rutile	TiO₂	Zr
Alkali Psilomelane	BaA1₂Ti₆O₁₆	Cs, Sr, Ba, Rb, A1

Sample	State	Temperature/ ℃	(SA/V)/ (m^-1·g^-1)	Duration time/d
MCC-1	Static	40, 70, 90	10	3, 7, 14, 28
MCC-2	Static	150, 200, 250	10	3, 7, 14, 28
MCC-3	Static	90, 150	680
MCC-4	Dynamic	75
PCT-A	Static	90	1000	7
PCT-B	Static	90	1000^b	28
PCT-C	Static	40, 70, 90	1000^b	28
PCT-D	Static	90	1000^b	56, 182, 364…
PCT-E	Static	40, 70, 90	1000^b	56, 182, 364…