Occupational Dose Evaluation in Support of the Development of the
October, 2012
Rare Element Resources, Inc. Bear Lodge Project
19
Table 3.1 lists the activity concentration and total activity specified in 49 CFR 173.436
for natural uranium and thorium.
Table 3.1 Exempt Activity Concentrations and Activity Limits for Transportation
Radionuclide
Activity
concentration
for exempt
material
(pCi/g)
Activity limit
for exempt
consignment
(pCi)
Mass
concentration
for exempt
material
(wt %)
Mass limit
for exempt
consignment
(mg)
10 x Mass
concentration for
exempt material
(wt %)
Natural
Thorium
≤ 27
≤ 27,000
≤ 0.012
≤ 123
≤ 0.12
Natural
Uranium
≤ 27
≤ 27,000
≤ 0.004
≤ 38
≤ 0.04
Based on the concentrations of natural uranium and thorium in Table 2.1 and the amount of
material typically transported, most materials generated from the mining, PUG and Hydromet
operations would meet the DOT definition of radioactive material. Exemptions to the
requirements in 49 CFR 173, Subpart I are contained in 49 CFR 173.401. An exemption for
NORM is included as stated below:
(b) This subpart does not apply to:
(4) Natural material and ores containing naturally occurring radionuclides
which are not intended to be processed for use of these radionuclides, provided
the activity concentration of the material does not exceed 10 times the values
specified in §173.436
Table 3.1 provides the mass-based concentration in percent weight, below which NORM would
be exempted from DOT regulations for radioactive materials. If material requiring off-site
transport were to be produced at concentrations exceeding the exemption limits contained in
Table 3.1, the material would be classified as Low Specific Activity (LSA-1) material. The pre-
concentrate from the PUG process is the only material to be transported on public roadways and
based on the information in Table 2.1 would be classified as LSA-1 material. The transport
requirements for LSA-1 are straightforward and are in 49 CFR 173.427. These regulations
include requirements for but not limited to the following items:
1
Packaging
2
Placarding
3
Marking
4
Instructions to maintain shipment exclusive use
5
Shipping Papers
6
Emergency Response
