The
primary pathway by which radionuclides can move off-site is
through the air. Air is the primary focus of monitoring on and
around the INL.
Low
Volume Air Samplers
Radioactivity associated with airborne particulates is monitored
continuously by 18 ESER Program air samplers at 16 locations.
Three of these samplers are located on the INL, seven are
located off the INL near the boundary, and six are at locations
distant the INL. Placement
of these samplers is based on wind dispersal patterns and
regulatory requirements to monitor population centers. These
locations allow samplers
to be divided into INL, Boundary and Distant groups to determine
if there is a gradient of radionuclide concentrations,
increasing towards the INL.
Filters
are changed weekly at each station.
Each filter is screened for gross
alpha and gross
beta radioactivity using thin-window gas flow proportional
counting systems after waiting about four days for
naturally-occurring daughter products of radon and thorium to
decay. (Gross
versus Specific Analyses)
Weekly filters for each location collected during the quarter are
composited and analyzed for gamma-emitting
radionuclides. Composites
are also analyzed by location for strontium-90
(90Sr), or plutonium-238
(238Pu), plutonium-239/240
(239/240Pu), and americium-241
(241Am).
Gross
alpha and gross beta analyses are an excellent screening technique
to detect radioactivity in any environmental media. These
analyses look at the total activity in a sample from both
naturally-occuring and man-made radionuclides. The present
monitoring system will detect any increase in gross activity
levels. If an increase in an activity occurs in either
analysis, radionuclide specific analyses can be conducted to
resolve a source.
Charcoal
Filters
Charcoal
filters placed at each air sampling location are also collected
weekly. The cartridges are screened for Iodine-131 by gamma
spectrometry. Iodine-131
is of great interest because it is produced in relatively large
quantities by nuclear fission, is readily accumulated in human and
animal thyroids, and has a half-life of eight days.
This means any 131I that is detected would be
from a recent release of fission products.
Atmospheric
Moisture
Tritium
in water vapor is monitored at four locations: Idaho Falls,
Atomic City, Rexburg and Blackfoot. The samples are analyzed using liquid scintillation.
Gross
alpha and gross beta analyses are an excellent screening technique
to detect radioactivity in any environmental media. These
analyses look at the total activity in a sample from both
naturally-occuring and man-made radionuclides. The present
monitoring system will detect any increase in gross activity
levels. If an increase in an activity occurs in either
analysis, radionuclide specific analyses can be conducted to
resolve a source.