Airborne Activity General Dispersion Model - Panasonic PT-DZ12000U Operating Instructions Manual

Airborne Activity General Dispersion Model

Assume a 1 uCi (37 kBq) release of respirable Pu
large room measuring 12 x 12 x 3 meters with a ventilation
turnover rate of 7 volumes per hour.
The General Dispersion Model uses this 2ð formula for
volume.
Volume in cm
@ distance R
Concentration @ distance R
in uCi / cc
Time required for the airborne wave front to reach distance R
1 CFM sample for 1 week equals 10,080 CF (285.4 M )
2 CFM sample for 1 week equals 20,160 CF (571 M )
Calculating Airborne Radioactivity (long-lived)
C = R / (V x î x SA x CE x CF)
S N
C = activity concentration at end of sample run time
S
R = net counting rate
N
V = sample volume
î = detector efficiency
SA = self-absorption factor
CE = collection efficiency
CF = conversion from disintegrations per unit time to activity
Calculating Airborne Radioactivity (short-lived)
C = R / [V x î x SA x CE x CF x (1-e
S N
Ts = sample count time
Tb = time elapsed between end of sample collection time
and start of sample count time
V = 2/3ð x R
3
30 cm
5.65E4
1.77E-5
13 sec
3
1 M
2.09E6
4.78E-7
43 sec
-ëTs
) x (e
239
inside a
10 M
2.09E9
4.78E-10
7.15 min
3
3
-ëTd
)]