Section 39.39 - Records of material use(a) Each licensee shall maintain records for each use of licensed material showing- (1) The make, model number, and a serial number or a description of each sealed source used;(2) In the case of unsealed licensed material used for subsurface tracer studies, the radionuclide and quantity of activity used in a particular well and the disposition of any unused tracer materials;(3) The identity of the logging supervisor who is responsible for the licensed material and the identity of logging assistants present; and(4) The location and date of use of the licensed material.(b) The licensee shall make the records required by paragraph (a) of this section available for inspection by the Commission. The licensee shall retain the records for 3 years from the date of the recorded event.