10 CFR 20.1005 : Energy (§ 1.1 To Parts 1801-1899) — (§ 1.1 To Appendix S To Part 50) — Nuclear Regulatory Commission (§ 1.1 To Appendix S To Part 50) — Standards For Protection Against Radiation (§ 20.1001 To Appendix G To Part 20) — General Provisions (§ 20.1001 To § 20.1009) — Units of radioactivity.

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.

(a) One becquerel = 1 disintegration per second (s−1).

(b) One curie = 3.7 × 10 ¹⁰ disintegrations per second = 3.7 × 10 ¹⁰ becquerels = 2.22 × 10 ¹² disintegrations per minute.