Regional Basic Professional Training Course in Korea

Regional Basic Professional Training Course (BPTC) on Nuclear Safety
Vd ( f ) being the rate of dry deposit for family f.
5.5.1.3.2. Wet deposit (by washing of puffs)
Wet deposit is assumed to remove from each elementary volume of the puff a quantity
proportional to the concentration within it.
The rate of wet deposit on the ground per unit area at point (x, y), at instant t, is given by:
∞
DDH(x, y, 0, t) = ‐Λ ∫ AV(x, y, z, t)dz
in which:
Λ (s ‐1 ) = rate of washing by rain
0
the washing rate is a function of the intensity of the rain, in accordance with the
commonly adopted relationship:
Λ = 10 ‐4 I, where I is rain intensity in mm/h.
The depletion associated with this wet depositing, over a time interval dt is:
dQ
dt
+∞
∫ ∫
+∞
= − DDH ( x,
y,
0,
t)
dxdy
−∞
−∞
from which the quantity remaining in the puff at instant ti is deduced:
Qih(ti) = Qis exp( −Λ ti) [7]
in which Qis covers depletion by dry deposit.
At each calculation time increment, the instantaneous concentrations are corrected to allow,
[5]
[6]
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