BS ISO 7503-1:2016 pdf free

BS ISO 7503-1:2016 pdf free.Measurement of radioactivity一Measurement and evaluation of surface contamination
The instrument shall be properly calibrated before use in a calibration facility that can provide traceability to national standards. The calibration should confirm not only the dose rate accuracy but also that the Multi Channel Analyser (MCA) has been correctly set up. If the MCA is not properly set up, the instrument is not able to perform automatic nuclide identification. The user should understand that automatic nuclide identification is limited to those nuclides in the instrument library. If peaks occur in the gamma spectrum, that are not automatically identified, the photon peak energy should be assessed from the spectrum and the literature consulted to try and identify the parent radionuclide.
Alternatively, the user should consult with an experienced health physics professional or radio chemist.In a situation where there are a number of gamma emitting nuclides present, the instrument may be unable to resolve the individual photo peaks because the resolution of small Nal crystals is poor when compared with germanium crystals. In this situation, germanium detectors can be used instead.
The time taken to collect a spectrum is mainly dependent on the ambient background radiation and the level of contamination. If the background is high or variable, it may be difficult or impossible to collect an adequate spectrum. If the background is particularly high, it may cause a spectrum shift which prevents automatic nuclide identification. Well shielded apparatus is also recommended.
In most situations, it is possible to identify the individual radionuclide which is the major constituent of the surface contamination. For example, in a hospital which only uses 99mTc for routine diagnostic purposes and no other radionuclides are brought onto the site, the nature of the contamination is obvious. The surfaces which might have become contaminated may also be well-defined in terms of material and surface finish. In this scenario, it would be appropriate to calibrate the contamination monitor(s) directly with the radionuclide concerned by depositing traceable activities to samples of the surfaces that might be affected by contamination. Exposing the monitor to these surfaces, at defined distances, provides a series of calibration factors which, during normal monitoring procedures, can be selected according to the relevant monitoring characteristics such as the nature of the surface, source to detector separation, and contamination area. These calibration factors can be expressed in units of response per unit area (activity per unit area).BS ISO 7503-1 pdf download.