25
as a function of time, t, for a given shot,
D(A),
curies of mass chain A for 1-kt fission
yield as a function of time, calculated by the
ORIGEN computer program with the 2334
235 yy 238) and 2392405, data omitted
(table in computer program).
KT
5.
kilotons of fission yield (input data).
External gamma-ray exposure rates
Assume that the fallout is distributed uniformly over 1 square
kilometer.
The external gamma-ray exposure rate for each
individual nuclide measured 1 meter above ground level is
given by
MR(A), = CIA), * C(A),
where MR(A),. = mR/hr measured 1 meter above ground
level due to mass chain A as a function of time.
C(A) = conversion factor (Be80), (mR/hr) /(Ci/km*),
(table in computer program), the value is
defined by specifying the relaxation length*
(input data).
* According to H. L. Beck, (Be80) the concentration of fallout varies
exponentially with soil depth, z; C = Coe4, He defines
relaxation length as 1/a.