PDF(Pubmed)
Abstract：
Bentonite is an integral part of the engineered barrier system (EBS) in deep geological repositories (DGR) for nuclear waste, but its indigenous microorganisms may jeopardize long-term EBS integrity. To predict microbial activity in DGRs, it is essential to understand microbial reactions to the early hot phase of DGR evolution. Two bentonites (BCV and MX-80) with varied bentonite/water ratios and saturation levels (compacted to 1600 kg.m- 3 dry density/powder/suspension), were subjected to heat (90-150 °C) and irradiation (0.4 Gy.h- 1) in the long-term experiments (up to 18 months). Molecular-genetic, microscopic, and cultivation-based techniques assessed microbial survivability. Exposure to 90 °C and 150 °C notably diminished microbial viability, irrespective of bentonite form, with negligible impacts from irradiation or sample type compared to temperature. Bentonite powder samples exhibited microbial recovery after 90 °C heating for up to 6 months but not 12 months in most cases; exposure to 150 °C had an even stronger effect. Further long-term experiments at additional temperatures combined with the mathematical prediction of temperature evolution in DGR are recommended to validate the possible evolution and spatial distribution of microbially depleted zones in bentonite buffer around the waste canisters and refine predictions of microbial effects over time in the DGR.
摘要：
膨润土是核废料深层地质储存库（DGR）中工程屏障系统（EBS）的组成部分，但其本土微生物可能会危及EBS的长期完整性。为了预测DGR中的微生物活性，了解微生物对DGR演化早期热期的反应至关重要。两种膨润土（BCV和MX-80），具有不同的膨润土/水比例和饱和度（压实至1600kg。m-3干密度/粉末/悬浮液)，进行加热（90-150°C）和辐照（0.4Gy。h-1）在长期实验中（长达18个月）。分子遗传学,微观,和基于培养的技术评估微生物的生存能力。暴露于90°C和150°C显着降低微生物活力，无论膨润土形式如何，与辐射或样品类型相比，温度的影响可忽略不计。膨润土粉末样品在90°C加热长达6个月但在大多数情况下不是12个月后表现出微生物恢复;暴露于150°C具有更强的效果。建议在其他温度下进行进一步的长期实验，并结合DGR中温度演变的数学预测，以验证废物罐周围膨润土缓冲区中微生物耗尽区的可能演变和空间分布，并完善对微生物随时间变化的预测DGR。
