10 CFR § 39.49
Uranium sinker bars
June 9, 2020
The licensee may use a uranium sinker bar in well logging applications only if it is legibly impressed with the words “CAUTION—RADIOACTIVE-DEPLETED URANIUM” and “NOTIFY CIVIL AUTHORITIES (or COMPANY NAME) IF FOUND.”
[65 FR 20345, Apr. 17, 2000]