Download - Nucleonix

GAMMA SOURCES:
Cs-137: (3.1µCi, July'07) ; Half life for Cs-137 is T1/2 = 30Yrs
Activity (A0)
=
3.1µCi, as on Oct'06.
=
3.1X3.7X1010X10-6
=
114700 Bq
(Elapsed time till Sept'07= 2months)
Present activity (A) =
T1/2 =
t
=
=
=
A0 e-(0.693/ T1/2) t; as on Sept'07
30yr
2/12=0.1666yr
114700 e-(0.693/ 30) 0.1666
114264.14 Bq
Co-60: (3.7µCi, July'07) ; Half life for Co-60 is T1/2 = 5.3Yrs
Activity (A0)
=
3.7µCi, as on Oct'06.
=
3.7X3.7X1010X10-6
=
136900 Bq
(Elapsed time till Sept'07= 2months)
Present activity (A) =
T1/2 =
t
=
=
=
A0 e-(0.693/ T1/2) t; as on Sept'07
5.3yr
2/12=0.1666yr
136900 e-(0.693/ 5.3) 0.1666
133961.2 Bq
b. DOSE RATE CALCULATION
Dose rate can be calculated by using the following formula
Source Activity x gamma constant
Dose rate = ___________________________
(Distance)2
where
Dose rate is in mR (milli Roentgen)
Source Activity is in mCi (milli Curies)
Distance is in cm (Centimeters)
Gamma constant for Cs-137 is 3300
and gamma constant for Co-60 is 13200
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