---
kind: "section"
citation: "10 C.F.R. § 20.1005"
title: "10"
number: "20.1005"
heading: "Units of radioactivity."
url: "https://uscodex.org/cfr/10/20.1005"
---

# §20.1005. 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<I>−1</I>).**
- (b) One curie = 3.7 × 10 10 disintegrations per second = 3.7 × 10 10 becquerels = 2.22 × 10 12 disintegrations per minute.

## Notes

### Amendments

[56 FR 23391, May 21, 1991; 56 FR 61352, Dec. 3, 1991]

### Source

Source: 56 FR 23391, May 21, 1991, unless otherwise noted.

### Authority

Authority: Atomic Energy Act of 1954, secs. 11, 53, 63, 65, 81, 103, 104, 161, 170H, 182, 186, 223, 234, 274, 1701 (42 U.S.C. 2014, 2073, 2093, 2095, 2111, 2133, 2134, 2201, 2210h, 2232, 2236, 2273, 2282, 2021, 2297f); Energy Reorganization Act of 1974, secs. 201, 202 (42 U.S.C. 5841, 5842); Low-Level Radioactive Waste Policy Amendments Act of 1985, sec. 2 (42 U.S.C. 2021b); 44 U.S.C. 3504 note.

### Amendments

[56 FR 23391, May 21, 1991; 56 FR 61352, Dec. 3, 1991]