[Code of Federal Regulations] [Title 10, Volume 1] [Revised as of January 1, 2004] From the U.S. Government Printing Office via GPO Access [CITE: 10CFR39.51] [Page 633] TITLE 10--ENERGY CHAPTER I--NUCLEAR REGULATORY COMMISSION PART 39--LICENSES AND RADIATION SAFETY REQUIREMENTS FOR WELL LOGGING --Table of Contents Subpart C--Equipment Sec. 39.51 Use of a sealed source in a well without a surface casing. The licensee may use a sealed source in a well without a surface casing for protecting fresh water aquifers only if the licensee follows a procedure for reducing the probability of the source becoming lodged in the well. The procedure must be approved by the Commission pursuant to Sec. 39.13(c) or by an Agreement State.