Interim Baseline Radiological Investigation Report
November 14, 2012
Bear Lodge Project, for Rare Element Resources, Ltd.
Rev.1
30
6.0
RADON FLUX MEASUREMENTS
This section summarizes the results of baseline Radon-222 (Rn-222) flux measurements
conducted in accordance with Section 2.3.6 of the SAP. Field data and analytical results
supporting the Rn-222 flux data are contained in Appendix C.
In accordance with the SAP, Rn-222 flux rates were measured at five locations, which coincided
with sample locations as shown on Figure 4.1. Five, plus two duplicate canisters were deployed
and retrieved on August 14 and 15, 2011, respectively. These canisters were analyzed using EPA
Test Method 115,
Monitoring for Radon-222 Emissions
.
Table 6.1 lists Ra-226 concentrations in corresponding soil samples. Rn-222 flux rates ranged
between 0.94 and 11.11 picocuries per meter squared second (pCi/m
2
-s). These values are below
the National Emissions Standards for Hazardous Air Pollutants (NESHAPS) requirement of 20
pCi/m
2
-s prescribed in 10
Code of Federal Regulations
40, Appendix A, Criterion 6. Although
the latter requirement applies to tailings and thus is not directly germane to this characterization,
it is useful as a context to demonstrate the relative magnitude of baseline radon flux levels
measured in the areas where construction and mining activities are anticipated to occur. With the
exception of Sample Location SS-33-SS-081311, Rn-222 fluxes increase with increasing Ra-226
concentrations; however, there are too few data points to consider additional trends.
Table 6.1. Radon Flux Results
Radon-222 (pCi/m
2
-s)
Sample Location
Rn-222
Flux
Flux Error
(±1σ)
LLD
Average Flux
Ra-226
Concentration
(pCi/g)
SS-05-SS-081211
a
2.21
0.07
2.21
1.85
1.2
1.48
0.06
1.48
SS-33-SS-081311
11.11
0.20
11.11
11.11
3.4
SS-23-SS-081211
6.26
0.13
6.26
6.26
4.8
SS-13-SS-081311
0.94
0.06
0.94
0.94
0.9
SS-35-SS-081311
a
7.18
0.14
7.18
6.84
9.8
6.49
0.13
6.49
Notes:
a
Duplicate canister deployed.
LLD = lower limit of detection
Ra-226 = Radium-226
pCi/g = picocuries per gram
Rn-222 = Radon-222
pCi/m
2
-s = picocuries per meter squared second
σ = standard deviation
