Final report on feasibility of real-time geochemical analysis at Yucca Mountain, Nevada, using LIBS technology

摘要

Laser-induced breakdown spectroscopy (LIBS) is an analytic method whereby an intense laser pulse is used to vaporize and excite a small volume of material into atomic emission. Calibrated spectral analysis of the laser spark light provides detection and quantification of the elemental composition of the target material. We performed laboratory and field tests to assess the feasibility of developing field-portable LIBS-based instruments for real-time analyses of Yucca Mountain rocks in conjunction with Yucca Mountain Project drilling, coring, sampling, and characterization tasks. We developed one prototype instrument designed to analyze air core drilling dust and another prototype instrument designed to analyze rock and fracture surfaces. In realistic field tests at the Exploratory Studies Facility at Yucca Mountain, Nevada, we demonstrated that the LIBS prototypes are capable of measuring major, minor, and some trace elements in real time. Laboratory LIBS analyses show that we can identify characteristic element ratios in a range of manganese oxide minerals present at Yucca Mountain as fracture surface coatings and matrix grains. Preliminary LIBS analyses also indicate that the U/Na ratio may distinguish tuffs containing the hazardous zeolite mineral erionite from non-erionite bearing tuffs, and that a LIBS-based instrument may be useful to detect in real time the probable presence of erionite encountered in core drilling and other operations at Yucca Mountain.