10 C.F.R. § 20.1005

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.