Section 144-220-G-C-61 - Calibration of survey instrumentsA. A licensee shall calibrate the survey instruments used to show compliance with this Part and Part D before first use, annually, and following a repair that affects the calibration. A licensee shall:(1) Calibrate all required scales with readings up to 10 mSv (1000 mrem) per hour with a radiation source;(2) Have each radiation survey instrument calibrated:(a) At energies appropriate for use and intervals not to exceed 12 months or after instrument servicing, except battery changes;(b) 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 three points between 0.02 and 10 millisieverts (2 and 1000 mrem) per hour; and(c) For dose rate instruments, so that an accuracy within plus or minus 20 percent of the true radiation dose rate can be demonstrated at each point checked.; and(3) Conspicuously note on the instrument the apparent dose rate from a dedicated check source as determined at the time of calibration, and the date of calibration.B. A licensee may not use survey instruments if the difference between the indicated exposure rate and the calibrated exposure rate is more than 20 percent.C. A licensee shall check each survey instrument for consistent response with a dedicated check source before each use.D. A licensee shall retain a record of each survey instrument calibration in accordance with G.206110-144 C.M.R. ch. 220, § G-C-61