Scope and object This International Standard is applicable to equipment intended for transportable or installed use for monitoring@ as a function of time@ airborne radioactive iodines (e.g. I@ 1251) in the environment (outside of buildings or facilities@ at heights typically from one to a few meters above the surface) of a nuclear facility during normal operations@ during anticipated operational occurrences or during accident conditions. For the purpose of this standard@ monitoring includes the continuous sample collection with@ if it is required@ the capability to automatically initiate sampling. This standard does not include equipment intended for monitoring radioactivity associated with gaseous effluents (at the stack). This type of equipment is covered in IEC 761-1 through IEC 761-5. This standard does not include monitoring for 129I Specific chemical species of radioactive iodines may be selectively collected by specialized sampling equipment according to the requirements specified by agreement between manufacturer and user. Such samples should be in the form appropriate for laboratory analysis. The radioactive iodines may be gaseous@ vapour or aerosol form. This standard is restricted to equipment for monitoring radioactive iodines in the atmosphere and does not address sample extraction and subsequent laboratory analysis. This standard does not specify tests with atmospheric radioactive nuclides. These may be treated in a future supplementary publication. The object of this International Standard is to identify specific standard requirements@ including technical characteristics and general test conditions. This standard provides criteria for the design@ selection@ functional testing and calibration of the instruments needed to perform the designated measurements. The general requirements concerning detection and measurement of ionizing radiation and nuclear instrumentation are given in IEC 50(391) and IEC 50(392). Additional terms concerning radiation protection are given in IEC 860.