IEC 60761-4:2002 pdf download

IEC 60761-4:2002 pdf download.Equipment for continuous monitoringof radioactivity in gaseous effluents -Part 4: Specific requirements for radioactiveiodine monitors.
IEC 61000 (all parts), Electromagnetic compatibility (EMC)
EN 55022:1994, Limits and Methods of Measurement of Radio Disturbance Characteristics of
Information Technology Equipment
3 Terms and definitions
For the purpose of this part of IEC 60761. the following definitions apply:
3.1
iodine
unless otherwise specified, the use of the word iodine in this standard covers radioactive iodine in all forms whether chemically combined or not, including iodine bound on aerosols
NOTE Iodine bound on aeosoe s in geiwaI trapped on a pefiter WhiCh should be analyzed separately in a laboratory.
3.2
iodine monitor
equipment designed for the continuous or sequential measurement of iodine in gaseous elfluents discharged to the environment
3.3
lit, time of the sampling medium
the time of sampling from operation with a medium to the time when the collection efficiency is equal to 90 % of the nominal value
4 Classification of iodine monitors
The equipment may be classified according to the type of radiation measured as:
— monitors for the measurement of lodine-131 only:
— monitors for the measurement of lodine-125 and/or lodine-129;
— monitors for the overall measurement of all iodine isotopes.
It may also be classified according to the method of operation, for example:
— equipment with static absorption medium and simultaneous measuremeni;
equipment with moving absorption medium and simultaneous measurement:
— equipment for the direct measurement of iodine in the stack or duct.
5 Sampling and detection assembly (where applicable)
5.1 Sampling and exhaust system
In addition to the general requirements of IEC 60761-1, the following characteristics shall be considered and shall be agreed upon between manufacturer and purchaser:
– the nature of the materials used paying particular attention to iodine adsorption:
— regulation of the temperature of the air passages to avoid condensation of Iodine or Its compounds.
5.2 Air pump
The requirements of clauses 11 and 29 of IEC 60761-1 are applicable.
Additionally, the air or gas pump shall be capable of maintaining the required air or gas I low- rate independently of differences in differential pressure induced by normal operating conditions (maximum expected sampling time. useable iodine retention devices, atmospheric dust, etc.) so that, at the end of sampling, there shall not be a reduction from nominal air flow- rate of more than 10 % or an error in the value of total air volume sampled of more than 8 %.
An alarm shall be fitted to detect both a rupture of the iodine retention medium (low differential pressure) and blockage of the medium (pressure difference greater than that required to give a 10 % drop in flow-rate).
5.3 Inlet filter
When appropriate, In the case of an iodine vapour monitor, a filter may be placed In a filter holder at the sampling circuit inlet to collect any dust and aerosols. In order to maintain the specific performance of the equipment, such a filter shall not trap or even temporarily retain iodine (except in aerosol form).
This device shall also be situated sufficiently far from the radiation detector or shielded, so that the filter contribution to the reading is insignificant.
5.4 Iodine collection medium
— The collection medium may have different geometries according to the method of operation of the assembly (see clause 4).
— The deposition of iodine should be as uniform as possible, Increased uniformity can be acheived through the use of an annular air passage.
— The iodine retention device design characteristics (dimensions, geometry, etc.) shall take account of the characteristics of the actual retention medium and the characteristics of the air (or gas) sampling pump.
— The presence of radioactive gases (for example 41Ar. Kr. 133Xe or 222Rn) in the air being monitored can have an effect on the monitoring of iodine, This is especially true for non- selective detectors. To reduce the effects of these radionuclides. the air space in the vicinity of the detector and inside the iodine collection medium shall be kept to the minimum possible, taking into account the requirements of 13.3.
— The design shall be such as to minimize air leaks, particularly internal leaks causing the flow to by-pass the iodine retention medium.
— Access to the iodine retention device and filter shall be such as to permit fast and easy removal without damage to either the radiation detector or the iodine retention device. Also. removal of the iodine retention device or the filter shall not expose personnel to an excessive dose of radiation.
— The manufacturer shall slate the life time of the iodine retention medium. This shall be at least eight days for reference conditions of temperature and relative humidity. The duration of sampling at 90 % of relative humidity shall be specified by the manufacturer.
5.5 Collection efficiency and retention behaviour
The manufacturer shall state the collection efficiency and the retention behaviour of the collection medium for elemental and volatile compounds of Iodine against various loading factors.