Section 20.1501 - General(a) Each licensee shall make or cause to be made, surveys of areas, including the subsurface, that-(1) May be necessary for the licensee to comply with the regulations in this part; and(2) Are reasonable under the circumstances to evaluate-(i) The magnitude and extent of radiation levels; and(ii) Concentrations or quantities of residual radioactivity; and(iii) The potential radiological hazards of the radiation levels and residual radioactivity detected.(b) Notwithstanding § 20.2103(a) of this part, records from surveys describing the location and amount of subsurface residual radioactivity identified at the site must be kept with records important for decommissioning, and such records must be retained in accordance with §§ 30.35(g) , 40.36(f) , 50.75(g) , 70.25(g) , or 72.30(d) , as applicable.(c) The licensee shall ensure that instruments and equipment used for quantitative radiation measurements (e.g., dose rate and effluent monitoring) are calibrated periodically for the radiation measured.(d) All personnel dosimeters (except for direct and indirect reading pocket ionization chambers and those dosimeters used to measure the dose to the extremities) that require processing to determine the radiation dose and that are used by licensees to comply with § 20.1201 , with other applicable provisions of this chapter, or with conditions specified in a license must be processed and evaluated by a dosimetry processor-(1) Holding current personnel dosimetry accreditation from the National Voluntary Laboratory Accreditation Program (NVLAP) of the National Institute of Standards and Technology; and(2) Approved in this accreditation process for the type of radiation or radiations included in the NVLAP program that most closely approximates the type of radiation or radiations for which the individual wearing the dosimeter is monitored.56 FR 23398, May 21, 1991, as amended at 63 FR 39482, July 23, 1998; 76 FR 35564 , June 17, 2011