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HW-80991
measurement results are tabulated in Appendix B, Table 1.
The concentra-
tions of beta emitters in air, filtered at several of the sampling locations,
during the pdst 3 years are shown in Figure 17.
The geographical locations
of these sampling stations are also shown.
During the early part of 1963, the activity observed on air filters
remained at nearly the level measured following USSR nuclear testing in the
fall of 1962.
Two peak activity periods occurred, one in February and one
in May indicating an influx of world-wide fallout.
ity, the highest since the fall of 1961,
mately 1 year old.
Analysis of the May activ-
indicated the material was approxi-
In August a very rapid decline in concentrations occurred
and by October the level was about 1 pc B/m?.
Results of air filter samples are not used in estimating exposure but
serve to illustrate the trends in atmospheric contamination.
Sudden changes
in concentrations are used to signal the need for shifted emphasis in other
portions of the environmental monitoring program related to atmospheric ~
contamination.
I.
External Radiation
Measurements with ionization chambers stationed above the ground
and submerged in the Columbia River were used to estimate the combined
exposure from external sources in the vicinity of the Hanford project.
Measurements over the ground indicated that the annual exposure for 1963
was about 170 mr, essentially the same as measured during 1962.
Virtually
all of this radiation originates from natural background and world-wide failout from nuclear testing and any additional contribution from Hanford sources
is not readily discernible.
Background measurements were relatively low
' during the first part of the year, and then increased duringthe latter half of
the year.
Measurements of external radiation in 1961,
1962, and 1963'are
shown in Figure 18 and are tabulated in Appendix D, Table 1.
Immersion dose measurements were obtained with pocket-type ioni-
zation chambers submerged 2 to 5 feet below the surface of the Columbia
River.
Exposure rates in the river are higher than those measured over land