Section 120.438 - Calibration of Survey Instruments(A) The registrant shall ensure that the survey instruments used to show compliance with 105 CMR 120.430 have been calibrated before first use, at intervals not to exceed 12 months, and following repair.(B) To satisfy the requirements of 105 CMR 120.438(A), the registrant shall: (1) Calibrate all required scale readings up to ten mSv (1000 mrem) per hour with an appropriate radiation source that is traceable to the National Institute of Standards and Technology (NIST);(2) Calibrate at least two points on each scale to be calibrated. These points should be at approximately 1/3 and 2/3 of full-scale; and(3) Calibrate automatically ranging digital display survey instruments at no less than one point on each decade and at no less than two points on one of these decades. These points should be at approximately 1/3 and 2/3 of the decade.(C) To satisfy the requirements of 105 CMR 120.438(B), the registrant shall: (1) Consider a point as calibrated if the indicated dose rate differs from the calculated dose rate by not more than 10%; and,(2) Consider a point as calibrated if the indicated dose rate differs from the calculated dose rate by not more than 20% if a correction factor or graph is conspicuously attached to the instrument.(D) The registrant shall retain a record of each calibration required in 105 CMR 120.438(A) for three years. The record shall include: (1) A description of the calibration procedure; and(2) A description of the source used and the certified dose rates from the source, and the rates indicated by the instrument being calibrated, the correction factors deduced from the calibration data, the signature of the individual who performed the calibration, and the date of calibration.(E) The registrant may obtain the services of individuals licensed by the Agency, the U.S. Nuclear Regulatory Commission, an Agreement State, or a Licensing State to perform calibrations of survey instruments. Records of calibrations which contain information required by 105 CMR 120.438(D) shall be maintained by the registrant.