J. W. Schmidt, A. R. Johnson, B. M. Markes, S. M. McKinney, and C. J. Perkins
Several types of environmental media are sampled near nuclear facilities to monitor the effectiveness of waste
management and restoration activities, and effluent treatment and control practices. These media include air,
surface water and springs, surface contamination, soil and vegetation, investigative sampling (which can
include wildlife), and external radiation. Sampling and analysis information and analytical results for 1994
for each of these media are summarized below. Additional data and more detailed information may be found
in Westinghouse Hanford Company Operational Environmental Monitoring Annual Report, Calendar Year
1994 (Schmidt et al. 1995).
Near-Facility Environmental Monitoring at Hanford
Near-facility environmental monitoring is defined as routine monitoring near facilities that have potential to
discharge or have discharged, stored, or disposed of radioactive or hazardous contaminants. Monitoring
locations are associated mostly with major nuclear facilities, such as the PUREX Plant and N Reactor, and
waste storage or disposal facilities such as burial grounds, tank farms, ponds, cribs, trenches, and ditches.
Much of the monitoring program consists of collecting and analyzing environmental samples and
methodically surveying areas near waste sites and facilities releasing effluents and waste streams. The
program also evaluates acquired analytical data, determines the effectiveness of facility effluent monitoring
and controls, measures the adequacy of containment at waste disposal units, and detects and monitors unusual
conditions. The program implements applicable portions of DOE Orders 5400.1, 5484.1, 5400.5, and
5820.2A.
Monitoring activities routinely include sampling and monitoring ambient air, water from surface-water
disposal units, external radiation dose, soil, sediment, vegetation, and animals. Some of the parameters
typically monitored are pH, radionuclide concentrations, radiation exposure levels, and concentrations of
some hazardous chemical constituents. Samples are collected from known or expected effluent pathways.
These pathways are generally downwind of potential or actual airborne releases and downgradient of liquid
discharges. The annual routine activities of near-facility monitoring are summarized in Table 3.2.1, which
shows the type, quantity, and location of samples collected. A detailed discussion of results for ground-water
wells used specifically to monitor operating facilities may be found in Schmidt et al. (1995).
Waste disposal sites and the terrain surrounding them are surveyed to detect and characterize any radioactive
surface contamination. Routine survey locations include cribs, trenches, retention basin perimeters, pond
perimeters, ditch banks, solid waste disposal sites (for example, burial grounds, trenches), unplanned release
sites, tank farm perimeters, stabilized waste disposal sites, roads, and firebreaks in and around the Site
operational areas.
Air Monitoring
Near-facility air sampling monitors the effectiveness of waste management and effluent treatment and
controls in reducing liquid effluents and air emissions; these systems also monitor diffuse source emissions.
Sample Collection and Analysis
Radioactivity in air was sampled by a network of continuously operating samplers at 41 locations near nuclear
facilities: four were located in the 100-N Area, four were in the 100-K Area, 31 were in the 200 Areas, one
was located near the 300 Area Treated Effluent Disposal Facility, and one station was collocated with
samplers operated by the Surface Environmental Surveillance Project and the DOH at the Wye Barricade. To
avoid duplication of sampling, the near-facility environmental monitoring program used existing Surface
Environmental Surveillance Project air samplers in the 300 and 400 Areas. Results for these areas are
reported in Section 5.2, "Air Surveillance," and are not discussed here. Air samplers were primarily located
at or near (within approximately 500 m [1500 ft]) sites and/or facilities having the potential for, or history of,
environmental releases, with an emphasis on the prevailing downwind directions.
Samples were collected according to a schedule established before the monitoring year (Schmidt 1993).
Airborne particles were sampled at each of these stations by drawing air through a glass-fiber filter. The
filters were collected biweekly, field-surveyed for gross radioactivity to detect any unusual trends or
off-normal occurrences, held for at least 7 days, and then analyzed for total alpha and beta activity. The 7-day
holding period was necessary to allow for the decay of naturally occurring radionuclides that would otherwise
obscure detection of longer-lived radionuclides associated with emissions from nuclear facilities. The total
radioactivity measurements were used to indicate changes in trends in the near-facility environment.
For most radionuclides, the amount of radioactive material collected on a single filter during a 2-week
sampling period was too small to be measured accurately. The accuracy of the sample analysis was increased
by compositing the samples into one biannual sample for each location. Each biannual composite sample was
then sent to International Technology Corporation, Inc. (Richland, Washington), to be analyzed for
plutonium-238, plutonium-239,240, strontium-90, uranium-234, -235, -238, and gamma-emitting (e.g.,
cesium-137, cobalt-60) radionuclides.
Results
Of the radionuclide analyses performed, cesium-137, plutonium-239,240, strontium-90, and uranium were
consistently detectable in the 200 Areas and cobalt-60 was detectable in the 100-N Area. Air concentrations
for these radionuclides were elevated near facilities compared to the concentrations measured offsite. Figure
3.2.1
shows average values for 1994 and the preceding 5 years for selected radionuclides compared to Derived
Concentration Guides and the background air concentration as measured by the Surface Environmental
Surveillance Project. The Derived Concentration Guides are reference values that are used as indices of
performance. The data indicate a large degree of variability. In general, samples collected from air samplers
located at or directly adjacent to nuclear facilities had significantly higher concentrations than did those
samples collected farther away. The data also show, as expected, that concentrations of certain radionuclides
were higher within different operational areas. Generally, the predominant radionuclides are activation
products (i.e., gamma emitters) in the 100 Areas and fission products in the 200 Areas. A more detailed data
summary is provided in Schmidt et al. (1995).
100-N Area
Analytical results from air samples taken in the 100-N Area continued to be at or near background for most
radionuclides as a result of facility shutdowns, improved effluent controls and waste management practices.
These levels were much less than the Derived Concentration Guides; however, they were greater than levels
measured offsite.
100-K Area
Analytical results from air samples taken in the 100-K East Area showed radionuclide concentrations at or
near minimum detection levels. This was the first year for environmental air sampling at the 100-K East
Area, thus trend analysis was not possible.
200 Areas
Analytical results from air samples taken in the 200 Areas were on a downward trend for most radionuclides
as a result of facility shutdowns, better effluent controls, and improved waste management practices. These
levels, although much less than the Derived Concentration Guides, were greater than levels measured offsite
and were higher for plutonium-239,240, strontium-90, and uranium than levels measured in the 100-N Area.
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