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  • 1 Harry Reid Center for Environmental Studies, University of Nevada Las Vegas (UNLV), 4505 Maryland Parkway, Las Vegas, NV 89154, USA
  • 2 Department of Chemistry, UNLV, Las Vegas, USA
  • 3 Department of Geoscience, UNLV, Las Vegas, USA
  • 4 Department of Earth and Environmental Sciences, New Mexico Institute of Mining and Technology, MSEC 202, 801 Leroy Place, Socorro, NM 87801, USA
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Samples of rock, soil and seepage were collected from Yucca Mountain, USA, and analyzed for 36Cl/Cl ratios by accelerator mass spectrometry (AMS). Rock excavated from the Drill Hole Wash fault at repository horizon depths produced a ratio suggesting that small amounts of water with “bomb-pulse” 36Cl had percolated to that site over the past 50 years. Rock from four other sites within the exploratory studies facility did not yield bomb-pulse ratios. Ratios in the soil varied depending on depth and location, with some samples producing bomb-pulse signatures. Ratios for seep water were slightly elevated above the present cosmogenic background value. This paper also discusses results from a column study mimicking the passage of 36Cl through volcanic rock and from an experiment using bromide instead of chloride as a carrier in sample preparation for AMS.