Section 34.25 - Radiation survey instruments(a) The licensee shall keep sufficient calibrated and operable radiation survey instruments at each location where radioactive material is present to make the radiation surveys required by this part and by 10 CFR part 20 of this chapter. Instrumentation required by this section must be capable of measuring a range from 0.02 millisieverts (2 millirems) per hour through 0.01 sievert (1 rem) per hour.(b) The licensee shall have each radiation survey instrument required under paragraph (a) of this section calibrated-(1) At intervals not to exceed 6 months and after instrument servicing, except for battery changes;(2) For linear scale instruments, at two points located approximately one-third and two-thirds of full-scale on each scale; for logarithmic scale instruments, at mid-range of each decade, and at two points of at least one decade; and for digital instruments, at 3 points between 0.02 and 10 millisieverts (2 and 1000 millirems) per hour; and(3) So that an accuracy within plus or minus 20 percent of the calibration source can be demonstrated at each point checked.(c) The licensee shall maintain records of the results of the instrument calibrations in accordance with § 34.65 .