Treatment of Air Sample Results
I.
Take Activity in Bq
2.
Divide by sample time in minutes§
3.
Call this number X
4.
Divide the factor for the isotope of interest given in Table I by X, this gives time in hours to reach ERL this is based on the lower ERL for sheltering, except for the isotopes marked with an asterisk which are based on the lower ERL for issue of stable iodine as well as sheltering.
TABLE I
Isotope
Factort
Sr-89
7.8 X 103
Sr-90
7.8 X 102
Ru-103
1.5 X 104
Ru-106
3.1 X 102
*Te-132
6.1 X 103
*I-13 1
1.1 × 103‡
*1-132
3.6 × 104
*1-133
6.4 × 103
*1-135
1.8 X 104
Cs-134
3.6 × 103
Cs-137
4.7 X 103
Ba-140
9.7 × 104
La-140
I. I X 104
Ce-144
3.8 X 102
Pu-238
0.64
Pu-239
0.56
Pu-240
0.56
Pu-241
24.4
Am-241
0.21
Cm-242
0.81
Cm-244
0.39
+ Note these factors are based upon values given in reference 20.
If no data is available on isotopic composition use [-131 data.
§ Assuming a standard to litres per minute portable sampler has been used.
103