ENVIRONMENTAL
HALF-LIFE OF 137CS
Current dose estimates are based only on radiological
decay (T1/2=3001Y
for
137CS).
Environmental
processes do eliminate
137CS from the ecosystem
Effective half-life AE = xradiological
As an example,
+
to the groundwater.
xenvironmental.
if ‘E is about 30y, the estimated doses would be half of the
currently estimated
doses.
Thus, TEis a very important parameter to kn~w.
No historical data to evaluate XE (or TE).
TE is a time dependent
process; thus, evaluating TE takes time.
Current experiments
1.)
Six trees on Enewetak Atoll first sampled in 1973.
since then.
2.)
Approximately
Last sampled in February 1986.
30 trees on Bikini Atoll first sampled in 1978-1979.
Sampled at least annually
3.)
Sampled periodically
since then.
About eight sites first sampled in 1959 by the University of Washington
have been resampled
in February of this year.
years, respectively.
2’
Thus, we could gain 27