Development of functional characteristics of vehicle mounted plastic scintillation system

To meet the Yucca Mountain Site Characterization Project Office preactivity survey schedules, increase efficiency, and reduce labor costs, SAIC implemented the use of a Vehicle Mounted Radiation Detector (VMRD). The VMRD consists of two systems, a Global Positioning System (GPS) and a Radiation Detection System (RDS). This paper focuses on the functional characteristics of the RDS. The functional characteristics of the TSA Model GPRS-100 Vehicle Mounted Global Positioning Radiometric Scanner were studied. The tests performed during this study were limited to gamma ray energies between 275 keV and 1275 keV, and source strengths between 16 kBq and 318 kBq. The system's efficiency as a function of vehicle speed, gamma ray energy, detector height, and source activity are presented. The system's efficiency as a function of detector height for Cs-137 ranged from 3.14% for a detector height for Cs-137 ranged from 3.14% for a detector height of 15 cm, to 0.91% for a detector height of 60 cm. The system's efficiency is not dependent upon gamma ray energy or source activity for the sources used in this study. It was determined that the system's efficiency as a function of speed falls within a predictable range dependent upon detector height and vehicle speed. For performing large area preactivity surveys a detector height of 60 cm and vehicle speed of less than 2.5 m/s will optimize this system's efficiency