BS EN 62363-2011 pdf download.Radiation protection instrumentation Portable photon contamination meters and monitors.
7.6.3 RequIrements — secondary batteries (rechargeable)
When power is supplied by secondary batteries, the capacity of these shall be such that after 8 h of continuous use, the indication of the assembly shall remain within ±5 %. other functions remaining within specifications.
If secondary batteries are used, it shall be possible to recharge the batteries from the mains supply within 16 Ii. The use of a device which switches off the charger when the complete charge is obtained Is recommended.
7.6.4 Method of test
The evaluation of the remaining battery capacity may be undertaken either by measuring the actual voltage of the internal batteries or, especially for secondary batteries, by performing charge measurements during use and recharging.
If the actual voltage is measured, the test shall be performed as follows. The internal batteries shall be removed and the assembly connected to an external power supply via an adjustable series resistance. The power supply shall be set to the nominal battery voltage 1nom and the series resistance to zero. The assembly shall be switched on and allowed to stabilize at normal background levels. If the assembly has a separate battery test function, this shall be selected. If the assembly continuously monitors the battery condition, then the assembly shall be switched to the radiation measurement indication. The supply voltage shall then be reduced until the assembly first indicates that the battery condition is no longer adequate. This voltage L’i0 and the supply current .4, shall be noted. The supply voltage shall then be returned to the nominal value L”nom and the series resistance increased until the battery condition is no longer adequate. This resistance R10 shall be noted.
The assembly shall then be exposed to a radiation source of sufficient activity to give an indication close to the maximum of the range of indication. The supply voltage shall be set to the nominal value tjnom and the series resistance to zero. Any functions which increase the assembly’s demand on the battery shall be switched on, including the scale illumination, lamps and audio output. Then the assembly indication M1 nom shall be recorded. The supply voltage shall then be decreased to Ow and the assembly indication M01 recorded. The supply voltage shall then be returned to Unom and the series resistance Increased to R10 The assembly indication M1102 shall be noted and the assembly checked to ensure that any auxiliary functions selected are operating correctly.
The assembly shall meet the following criteria:
8.2.2 Method of test
To determine a detector profile, the detection assembly should be mounted I centrally Ji 0 mm above a small area source of an appropriate radionuclide The instrument reading should be recorded successively as the source Is moved radially away from the central position. In this fashion, a detector profile can be formed: an example of such a profile Is provided In Figure 1.
ln the case of a rectangular detector three profiles shall be taken. One from the centre in the direction normal to the shortest side of the sensitive area of the detector, another from the centre in the direction normal to the longest side of the sensitive area of the detector and one from the centre in the direction of a corner of the sensitive area of the detector. In the case of square detectors the first above is unnecessary. In the case of a cylindrical detector there is only a single profile.
The distance at which the net instrument reading falls to 1 % of the central value denotes the outer dimensions of the large area source required to perform a contiguous portions calibration. This is defined as the limit distance (see 3.23). Clearly, the dimensions of that large area source are dependent upon the size of the detector area of the monitor used, its structural characteristics and the energy of the radiation.
8.3 Surface emission rate response
8.3.1 General
Photon contamination meters and monitors will be sensitive to contamination that is found at a distance from the centre of the detection assembly that is considerably greater than the largest dimension of the detector window. Therefore the large area test source should have a smallest linear dimension that is greater than the limit distance evaluated when undertaking the detector profile in 8.2. However in practice, this area may be very large for detection assembliesIwith large sensitive volumes and/or areasJ. so for the purposes of standardisation, the largest linear dimension of the large area test source should not exceed 30 cm.
NOTE 1 A limit distance 0117 cm is equivalent to an effective sensitive area under the detector of 900 cm2 (c,rcle
of radius 17 cm). This area is simulated using a square large area test source with a linear dimension of 30 cm. NOTE 2 Annex A gives examples of limit distances.
If a large area test source of the required dimensions is unavailable, then the surface emission rate response shall be derived by undertaking a contiguous portions measurement. In the case of a 900 cm2 test source, this is then achieved with a square grid of six 150 cm2 or nine 100 cm2 test sources.
8.3.2 Type test
The surface emission rate response is dependent on the surface area of the test source, and its shape. The manufacturer shall state on the test certificate the surface emission rate response of the assembly to the appropriate reference radionuclide averaged over an area of both 30cm x 30cm (900 cm2): and an area of 10 cmx 10 cm or 15cm x 10cm.BS EN 62363-2011 pdf download.