Low radioactivity spectral gamma calibration facility

A low radioactivity calibration facility has been constructed at the Nevada Test Site (NTS). This facility has four calibration models of natural stone that are 3 ft in diameter and 6 ft long, with a 12 in. cored borehole in the center of each model and a lead-shielded run pipe below each model. These models have been analyzed by laboratory natural gamma ray spectroscopy (NGRS) and neutron activation analysis (NAA) for their K, U, and Th content. Also, 42 other elements were analyzed in the NAA. The /sup 222/Rn emanation data were collected. Calibrating the spectral gamma tool in this low radioactivity calibration facility allows the spectral gamma log to accurately aid in the recognition and mapping of subsurface stratigraphic units and alteration features associated with unusual concentrations of these radioactive elements, such as clay-rich zones

Monitoring and modeling for radon entry into basements: A status report for the small structures project

The approach, status, and initial findings of a research project on radon transport through soil and entry into buildings are described. We have constructed two room-size precisely-fabricated basements at a site with relatively homogeneous soil. The structures have adjustable-size openings to the soil, are otherwise very air-tight, and are mechanically ventilated using a system that also controls the indoor-outdoor pressure difference. Numerous probes have been installed in the soil surrounding the structures to permit multipoint measurement of soil moisture content, soil temperature, permeability of soil to air, soil-gas pressure and radon concentration. State-of-the-art instrumentation is being installed for real-time monitoring of these parameters plus structure ventilation rate, indoor and entering soil-gas radon concentrations, and meteorologic parameters for a period of at least one year. Many of the factors that control or influence radon entry will be modified intentionally or by changes in environmental parameters during the course of the measurements. We have found it necessary to design and fabricate a new type of probe for more accurate measurements of soil permeability. We have also verified and improved procedures for more accurate, rapid, multipoint measurements of radon concentrations using a continuous radon monitor. Identical structures, with the same instrumentation, will be constructed at additional sites with difference soil characteristics and climates. Core samples of the soil from each site are analyzed to determine density, porosity, permeability, radium content, and radon emmanation coefficient. The research project also includes steady-state and transient numerical modeling efforts that complement the experimental research and that will use the experimental data for model validation. 32 refs., 12 figs., 5 tabs