Interim Baseline Radiological Investigation Report
November 14, 2012
Bear Lodge Project, for Rare Element Resources, Inc.
Rev.1
7
3.0
GPS-BASED GAMMA (DIRECT RADIATION) SURVEY
This section documents the results of the baseline gamma radiation survey of the Project
conducted in August 2011. The findings discussed in this section are reflected largely in the
supporting figures; the text is limited to a discussion of trends and salient findings.
3.1 GPS Survey Methods
A GPS-based gamma survey was conducted at the Project on six days, between August 2 and 10,
2011. The detection systems were unshielded 2-in. by 2-in. sodium iodide detectors (Ludlum
Model 44-10), each of which was coupled to a ratemeter/scaler (Ludlum Model 2221, set in
ratemeter mode) and, in turn, a Trimble Pro XRS GPS Receiver with Trimble TSCe Datalogger.
With the exception of Miller Creek Road, survey transects were spaced at approximately 500 m
intervals. Scanning was performed at less than 1.5 meters per second (m/s) with differentially
corrected x- and y-coordinates and gamma count rates recorded every second. The survey was
conducted on foot while carrying the requisite equipment in backpacks, with the exception of the
work on Miller Creek Road, which was performed using an ATV. The detectors were held at
approximately 0.5 m above ground surface in the walking survey. They were fixed to the ATV at
the same height, for the survey of Miller Creek Road.
The survey instruments were in current calibration and function checked daily, before and after
use. Calibration and function forms are provided in Appendix A.
3.2 Results of GPS-Based Gamma Survey
The gamma count rate data obtained in the GPS-based survey were divided into those collected
in the Project and those along Miller Creek Road outside the Project.
The gamma count rates were converted into exposure rates, using the method and linear
correlation described in Section 3.3. The count rates are displayed as exposure rates in Figure
3.3, which is presented and discussed in Section 3.3. All of the statistical analyses and
summaries presented henceforth, including the illustrations, were developed using Minitab 15,
statistical software.
