Scholarlink

<p>Surface detection of signature noble gas radionuclides (RN) can provide positive confirmation of an Underground Nuclear Explosion (UNE). However, predicting RN gas migration in the subsurface following a UNE involves complex processes of gas migration through an intact and fractured rock, active rock damage including opening and closing of fractures, and fractionation of RN gases. In this study, we conducted Triaxial Direct Shear (TDS) experiments on granite samples relevant to the Nevada National Security Site to investigate the effects of hydro-mechanical coupling and rock damage induced by a UNE on the transport properties and fractionation behavior of signature noble gases through intact and fractured rock. The testing system features a low-pressure mass spectrometer integrated into the high-pressure TDS system, allowing for accurate characterization of signature noble gases migrating in subsurface conditions. Our results indicate that the gas permeability of intact granite is less dependent on the magnitude of the stress applied to it and more dependent on the applied pore pressure due to the Klinkenberg effect. We observed Klinkenberg effect up to 3.0&#xa0;MPa of differential pore pressure in intact granite, but this effect does not prevail in fractured granite. With respect to gas fractionation behavior, we observed that more diffusive helium (He) gas broke through later than less diffusive sulfur hexafluoride (SF<sub>6</sub>) gas in intact granite under higher effective stress conditions, which is attributed to the higher transverse diffusion of He. However, the more diffusive gas consistently broke through faster when migrating through fractures during pressure driven advective flow. The results from this study indicate that large fracture displacements, analogous to extensive rock damage during a UNE, homogenize breakthrough times as RN gases have more open flow paths available for migration. Overall, this study sheds light on the dynamics of subsurface RN gas migration during early post-UNE gas flow and provides crucial input data and validation for numerical models that will improve predictions of gas migration following a UNE.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Laboratory Investigation of Signature Gas Transport and Fractionation Behavior in Granite for Underground Nuclear Explosion Detection

  • 期刊论文

  • 发表日期：

    2025年9月1日

查看全文
  • Bijay KC,
  • Meng Meng,
  • Wenfeng Li,
  • Luke P. Frash,
  • Chelsea W. Neil,
  • Philip H. Stauffer

摘要

Surface detection of signature noble gas radionuclides (RN) can provide positive confirmation of an Underground Nuclear Explosion (UNE). However, predicting RN gas migration in the subsurface following a UNE involves complex processes of gas migration through an intact and fractured rock, active rock damage including opening and closing of fractures, and fractionation of RN gases. In this study, we conducted Triaxial Direct Shear (TDS) experiments on granite samples relevant to the Nevada National Security Site to investigate the effects of hydro-mechanical coupling and rock damage induced by a UNE on the transport properties and fractionation behavior of signature noble gases through intact and fractured rock. The testing system features a low-pressure mass spectrometer integrated into the high-pressure TDS system, allowing for accurate characterization of signature noble gases migrating in subsurface conditions. Our results indicate that the gas permeability of intact granite is less dependent on the magnitude of the stress applied to it and more dependent on the applied pore pressure due to the Klinkenberg effect. We observed Klinkenberg effect up to 3.0 MPa of differential pore pressure in intact granite, but this effect does not prevail in fractured granite. With respect to gas fractionation behavior, we observed that more diffusive helium (He) gas broke through later than less diffusive sulfur hexafluoride (SF6) gas in intact granite under higher effective stress conditions, which is attributed to the higher transverse diffusion of He. However, the more diffusive gas consistently broke through faster when migrating through fractures during pressure driven advective flow. The results from this study indicate that large fracture displacements, analogous to extensive rock damage during a UNE, homogenize breakthrough times as RN gases have more open flow paths available for migration. Overall, this study sheds light on the dynamics of subsurface RN gas migration during early post-UNE gas flow and provides crucial input data and validation for numerical models that will improve predictions of gas migration following a UNE.