IEEE 498-1985 pdf free.IEEE Standard Requirements for the Calibration and Control of  Measuring and Test Equipment Used in Nuclear Facilities.
IEEE 498 definitions are provided to assure a uniform understanding of selected termsas they are used in this standard.
accuracy. A measure of the degree by which theactual output of a device approximates the out-put of an ideal device nominally performing thesame function.calibration. Comparison of items of measuringand test equipment with reference standards orwith items of measuring and test equipment ofequal or closer tolerance to detect and quantityinaccuracies and to report or eliminate thoseinaccuracies.
measuring and test equipment.Devices or systems used to calibrate，measure，gage，test,inspect or control to acquire research，develop-ment,test or operational data or to determinecompliance with design,speciflcations or othertechnical requirements.
reference standards.Standards (that is, primary,secondary and working standards，where appro-priate) used in a calibration program. Thesestandards establish the basic accuracy limits forthat program.
tolerance. The allowable deviation from a specified or true value.
A documented program shall be established,implemented and maintained for the calibrationand control of measuring and test equipment andreference standards. It shall be designed to deter-mine and assure the accuracy of measuring andtest equipment and reference standards and shallprovide for the prompt detection of inaccuraciesand for timely and effective corrective action.This documented program shall include as a min-imum the following general requirements.Equipment Identification. A list of measuring and test equipment,and reference standardsand their assigned locations shall be prepared tospecifically identify those items within the calibration program.
Calibration Procedures.Documented pro-cedures for calibrating measuring and test equip-ment and reference standards shall be used.Procedures such as published standard practices,written instructions that accompany purchasedequipment,or other acceptable instructions maybe used.
The documented program shall include as aminimum the elements of control described inthe following subsections:
Adequacy of Reference Standards. Refer-ence standards used for calibrating measuringand test equipment shall have calibration ranges,precisions and accuracies so that the measuringand test equipment and plant equipment can becalibrated and maintained within the requiredtolerances.
Ingeneral,the inaccuracy of the referencestandards shall contribute no more than onefourth of the allowable measuring and test equip-ment tolerance. However，when the actual inac-curacy of the measuring and test equipment isless than one fourth of the plant equipment toler-ance,or if reference standards less than onefourth of the tolerance of the measuring and testequipment are not available，the requirement forone fourth may not be necessary. The rationalefor deviating from these requirements shall bejustified and documented.IEEE 498 pdf download.