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All
replies I have seen on this subject are correct. The primary isotope of
concern is Radium and it's associated daughters. This material (Black
Beauty) was used for years in the oil and gas industry. When state NORM
regulations came around, several companies were faced with the problem of
differentiating from the contamination from the grit and regulated NORM (most
all states with NORM regs exempt blasting grit). One oil company in
Louisiana had to remediate a significant plot of land where they used to blast
equipment because they could not prove the radium contamination did not come
from a regulated source. I have seen radium concentrations in this grit as
high as 60-70 pCi/gm. Most states with NORM regs regulate NORM at 30
pCi/gm (some at 5 pCi/gm). In one instance, I was able to convince a state
regulator to allow a client to use radium contaminated blasting grit (the client
said nothing else would do the job) by sampling the material by batch prior to
use and sampling the material after use. If the after use sample did not
exceed the before use sample by greater than the exemption level (i.e. by more
than 30 pCi/gm) then the blasting grit would maintain its' exemption.
However, I do not recommend its' use in potential NORM situations unless
absolutely necessary.
Mitchell Davis, RRPT
RSO,
NORM Decon Services, LLC
Midland, TX
915-563-1123
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