# 10 C.F.R. § 20.1005 (2026): Units of radioactivity

> Federal · Regulations · In force

URL: https://www.frixlaw.com/law-library/statutes/CFR_T10_P20_S20_1005

## Section

- **Citation:** 10 C.F.R. § 20.1005 (2026)
- **Heading:** Units of radioactivity
- **Jurisdiction:** Federal
- **Kind:** Regulations
- **Status:** In force
- **Text as of:** August 14, 2026
- **Source:** Compiled text
- **Location:** Title 10 CFR: Energy / Chapter I: NUCLEAR REGULATORY COMMISSION / Part 20: STANDARDS FOR PROTECTION AGAINST RADIATION / Subpart A: General Provisions / § 20.1005: § 20.1005   Units of radioactivity.

## Text

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

## Nearby sections

- [10 C.F.R. § 20.1001 (2026) § 20.1001   Purpose.](https://www.frixlaw.com/law-library/statutes/CFR_T10_P20_S20_1001.md)
- [10 C.F.R. § 20.1002 (2026) § 20.1002   Scope.](https://www.frixlaw.com/law-library/statutes/CFR_T10_P20_S20_1002.md)
- [10 C.F.R. § 20.1003 (2026) § 20.1003   Definitions.](https://www.frixlaw.com/law-library/statutes/CFR_T10_P20_S20_1003.md)
- [10 C.F.R. § 20.1004 (2026) § 20.1004   Units of radiation dose.](https://www.frixlaw.com/law-library/statutes/CFR_T10_P20_S20_1004.md)
- [10 C.F.R. § 20.1005 (2026) § 20.1005   Units of radioactivity.](https://www.frixlaw.com/law-library/statutes/CFR_T10_P20_S20_1005.md)
- [10 C.F.R. § 20.1006 (2026) § 20.1006   Interpretations.](https://www.frixlaw.com/law-library/statutes/CFR_T10_P20_S20_1006.md)
- [10 C.F.R. § 20.1007 (2026) § 20.1007   Communications.](https://www.frixlaw.com/law-library/statutes/CFR_T10_P20_S20_1007.md)
- [10 C.F.R. § 20.1008 (2026) § 20.1008   Implementation.](https://www.frixlaw.com/law-library/statutes/CFR_T10_P20_S20_1008.md)
- [10 C.F.R. § 20.1009 (2026) § 20.1009   Information collection requirements: OMB approval.](https://www.frixlaw.com/law-library/statutes/CFR_T10_P20_S20_1009.md)

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Source: Frix Law Library, https://www.frixlaw.com/law-library/statutes/CFR_T10_P20_S20_1005. Check the current official text before relying on it. Not legal advice.