This part of IEC 60761 is applicable to equipment intended for simultaneous, delayed or discrete sequential measurement of radioactive noble gas in gaseous effluents discharged into the environment. It is applicable to radioactive noble gas effluent monitors intended to fulfill the following functions: ñ the measurement of the volumic activity of radioactive gases in the gaseous effluents at the discharge point and its variation with time; ñ the actuation of an alarm when a predetermined volumic activity or a predetermined total released radioactivity is exceeded; ñ the determination of the gas activity discharged over a given period and/or information on the composition of a mixture of different gases in the discharge. Radon is a natural radioactive noble gas. Its measurement is not included in this standard. The presence of radon, or its decay products, may interfere with the measurement of other (artificial) radioactive gases. The object of this standard is to lay down specific standard requirements, including technical characteristics and general test conditions, and to give examples of acceptable methods for noble gas effluent monitors. The general requirements, technical characteristics, test procedures, radiation, electrical, mechanical, safety and environmental characteristics are given in IEC 60761-1. Unless otherwise stated, they apply to this part