Overview

Radioactive contamination of surfaces can result from spills, splashes, or leakage from open sources, or from rupture or loss of integrity of sealed sources, and can cause adverse health effects. The need for effective monitoring of surface contamination was recognized long ago. Surface contamination is expressed in units of activity per unit area, the quantity commonly used to indicate limits on maximum surface contamination. These limits are based on radiation protection considerations and were derived from the effective dose or activity input limits recommended by the International Commission on Radiological Protection (ICRP). While government regulations refer to surface contamination in units of activity per unit area, monitoring instrument readings are directly related to the radiation emitted from the surface, not the activity contained on or within the surface. Because of changes in the absorption and scattering characteristics of real surfaces, it cannot generally be assumed that there is a simple, known relationship between surface emission rate and activity. This results in the need for calibration radiators that are preferably specified in units of both surface emission rate and activity. This standard specifies the characteristics of reference sources of radioactive surface contamination, traceable to national measurement standards, for the calibration of surface contamination monitors, as well as preferred reference radiations for the calibration of surface contamination monitors. It relates to alpha-emitters, beta-emitters, and photon emitters of maximum photon energy not greater than 1,5 MeV. It does not describe the procedures involved in the use of these reference sources for the calibration of surface contamination monitors. Such procedures are specified in DIN EN 60325 (VDE 0493-2-1), DIN EN 62363 (VDE 0493-2-4) and other documents. The standard differs from DIN ISO 8769:2012-02 as follows: a) a definition of the front surface of a radiator has been included; b) "reference source" is used as the superordinate designation; c) instead of transfer standards, reference transfer meters are treated; d) the requirements for their detection probability have been changed; e) the general description in 5.1 has been extended; f) information on filter thickness as well as on calibration with 60Co has been added in Table 1; g) changes concerning the radionuclides recommended in Tables 2 and 3; h) Class 1 reference sources with an area of 150 mm × 200 mm have been included in 5.2; i) the definition of uniformity has been changed verbally to 3.7 without giving an exact formula. However, the calculation path given in 5.2.3 has not been changed, but the requirement for uniformity of Class 1 and Class 2 reference radiators has been changed from 10% to 90% (see National Footnotes to 5.2.3 and 5.3.3 for details) and the size of individual subareas has been doubled to a maximum of 10 cm²; j) for work sources, reference is made in 5.4 to the requirements for Class 2 reference sources (5.3) and no longer to the requirements for Class 1 reference sources (5.2); k) the bibliography has been supplemented. The responsible committee is DKE/GUK 967.2 "Aktivitätsmessgeräte für den Strahlenschutz" ("Radiation protection instrumentation") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.

Document: references other documents

Document: referenced in other documents

Responsible national committee

DKE/GK 851 - Aktivitätsmessgeräte für den Strahlenschutz  

Responsible international committee

ISO/TC 85/SC 2/WG 17 - Radioactivity measurements