S.C. Code Regs. § § 61-63.I.RHB 1.4

Current through Register Vol. 48, No. 10, October 25, 2024

Section 61-63.I.RHB 1.4 - Test and Surveys

1.4.1 For the purposes of this part, activity is expressed in the special unit of curies (Ci) or in the SI unit of becquerels (Bq), or their multiples, or disintegrations (transformations) per unit of time.

1.4.1.1 One becquerel = 1 disintegration per second (s^-1).

1.4.1.2 One curie = 3.7 X 10¹⁰ disintegrations per second = 3.7 X 10¹⁰ becquerels =2.22 X 10¹² disintegrations per minute. Commonly used submultiples of the curie are the millicurie (mCi) and the microcurie (uCi). One mCi = .001 curie (Ci) = 3.7 X 10⁷ dps or 2.22 X 10⁹ dpm. One uCi = .000001 Ci = 2.22 X 10⁶ dpm.

1.4.2 For purposes of these regulations, it may be assumed that the daughter activity concentrations in the following table are equivalent to an air concentration of 10-⁷ microcuries of Radon 222 per milliliter of air in equilibrium with the daughters RaA, RaB, RaC, and RaC [FN1]

Alpha-emitting daughter activity collected per millimeter of air
Maximum time between collection and measurement (hours) [FN*]	Microcuries/ml.	Total alpha disintegrations per minute per ml.
0.5	7.2 x 10-8	0.16
1	4.5 x 10-8	0.10
2	1.3 x 10-8	0.029
3	0.3 x 10-8	0.0067
[FN*] The duration of sample collection and the duration of measurement should be sufficiently short compared to the time between collection and measurement, as not to have a statistically significant effect upon the results.

[FN1] Note: The unit 'Ci' is the currently used abbreviation for 'curie' replacing the older unit 'c'. Where the unit 'c' occurs in the text or tables of these regulations, it is to be interpreted to mean 'Ci', likewise uc = uCi and mc = mCi.

S.C. Code Regs. § 61-63.I.RHB 1.4