ISO 8769-2020 pdf free download – Measurement of radioactivity — Alpha-, beta- and photon emitting radionuclides — Reference measurement standard specifications for the calibration of surface contamination monitors.
|Reference measurement standards shall be of the following two types:
Class 1: reference measurement standards that have been calibrated directly in terms of activityand surface emission rate at a national or international metrology institute.
Class 2: reference measurement standards that have been calibrated in terms of surface emissionrate on a reference transfer instrument, the efficiency of which has been measured by calibrationwith a Class 1 reference measurement standard of the same radionuclide and of the same generalconstruction using the same geometry, at a laboratory that operates according to ISO/IEC 17025l16]for such measurements.
National metrology institutes shall, at their discretion, provide the means whereby Class 1 reference
measurement standards of a specified range of radionuclides may be certified by them. For thosecountries which are signatories to the Mutual Recognition Arrangement (MRA)3, a certificate ofcalibration from another participating institute in a second country is recognized as valid in thefirst country for the quantities, ranges, and measurement uncertainties specified in Appendix C ofReference [9].
The activity and surface emission rate of Class 1 reference measurement standards shall be measured,using, for example, a windowless gas-flow proportional detector, or by using an instrument that hasbeen calibrated using standards that have been measured absolutely. calibration procedures foractivity determination are discussed for example, in References [10],[11],[12] and [13].
Organizations with a requirement to type test and to calibrate instruments to be used for monitoring
radioactive surface contamination need to have access to suitable Class 1 or Class 2 referencemeasurement standards. The purpose of a working measurement standard is to check the calibration
of surface contamination monitors in the field; they are not to be confused with check sources, whichare only intended to verify that a monitor is operating.
Organizations with a requirement to provide working measurement standards for the routineconfirmation of the calibration of their surface contamination monitoring instruments require accesstoa reference transfer measurement device with which to calibrate such working measurement standardsin terms of surface emission rate against a Class 1 or Class 2 reference measurement standard. Wherethe working measurement standard is used either in a jig or under a particular geometry, the referencetransfer measurement device on which its emission rate is measured shall have been calibrated using areference measurement standard under identical conditions and geometry.Alternatively, the workingmeasurement standard shall be removable from the jig so that it can be measured in the usual way.Where only a few monitors need calibration or a high degree of accuracy is required,Class 1 or Class 2reference measurement standards may be used as working measurement standards. In such cases, thefrequency of re-calibration shall be that for working measurement standards.National regulations mayrequire more frequent calibrations.
5 Specification of reference measurement standards5.1General
Reference measurement standards are of the following kinds:
a) Sources comprising an electrically conducting backing material with a given radionuclide
permanently deposited upon or incorporated into one side only; the thickness of the backing materialshall be sufficient to prevent emission of the particulate radiation through the back of the source.or
b) Sources comprising a layer of material within which the radionuclide is uniformly distributed and the thickness of which shall not exceed the thickness of the saturation layer of the particulate.ISO 8769 pdf download.