IEC 62533:2010 pdf – Radiation protection instrumentation-Highly sensitive hand-held instrumentsfor photon detection of radioactive material.
• low background level of 0.05 pSv h (± 50 %);
• Thigh background level of 015 llSv h-1 (i 20 %).
It Is important that, for the limited spectronletric based function (see 7.1 and 7.3). the spectral distribution of the background shall be realistic and represents a wide range of areas where the Instruments are likely to be used. The levels and appropriate spectra shape can be created for the testing purpose by. e.g.. granite blocks, ceramic tiles. etc.
5.4 Statistical fluctuations
For any test involving the use of radiation, If the magnitude of the statistical fluctuations of the Indication arising from the random nature of radiation alone is a significant traction of the variation of the Indication permitted in the test, then sufficient readings shall be taken to ensure that the average value of such readings may be estimated with sufficIent precision to determine whether the requirements for the characteristic under test are mel
The Interval between such readings shall be sufficient to ensure that the readings are statistically independent.
6 Radiation tests
61 Rate of false alarms (source indication)
6.1.1 Requirements
The number of source-indication false alarms shall not exceed I per hour. The length of each false alarm shall not exceed 3 s.
6.1.2 Test method
The alarm threshold settings used in this test and in 6.2 shall be the same.
Test shall be carried out at low and high background conditions with the instrument being monitored for 10 h.
The number of false source indication alarms during this period shall not exceed 10 for each instrument tested over the 10 h period. The length of each false alarm shall not exceed 3 s.
6.2 Source alarm and response time
&21 Requirements
The instrument shall alarm when ills exposed to an Increase of the ambient dose equivalent rate equal or greater than 0.05 piSv h within 3 s of the step change. In addition, the displayed ambient dose equivalent rate indication shall be within ±30 % of the changed ambient dose equivalent rate within 5 s of the change. The requirement should be met for “4Am, 137Cs and °Co sources.
6.2.2 Test method
This test shall be made after the false alarm test (6.1) and using the same settings as for the false alarm test.
Turn on the instrument in the Thigh background condition. Increase the dose equivalent rate by 0.05 pSv within 1 s using the 37Cs source. Observe the instrument’s response. The alarm shall be activated within 3 a of the step change, and the indicated ambient dose equivalent rate shall be within ±30 % of the radiation level within 5 a of the change. The alarm shall then be acknowledged and the process repeated nine additional times. Results are acceptable when the alarm is activated at least 9 out of 10 exposures.
The test shall be repeated with the 241p and 60Co sources
The test shall be repeated for the 1ow background condition.
6.3 Personal protection alarm and response tIme
6.3.1 Requirements
The instrument shall alarm when it is exposed to an increase in the ambient radiation level greater than personal protection alarm threshold within 2 s of the step Change.
6.3.2 Test method
Using a 37Cs source, increase the ambient dose equivalent rate at the reference position to 30 % above the personal-protection threshold (e.g., threshold of 10 IlSv h1). This shall trigger a personal protection alarm in less than 2 a.
6.4 Ambient dose equivalent rate indication
6.4.1 Requirements
Under standard test conditions, the response of the instrument to the reference photon radiation shall not exceed ± 30 % for all ambient dose equivalent rates from 0,1 iiSv h1 up to the upper stated limit.
6.4.2 Test method
Before and after the tests, take the instrument’s background reading and determine the mean background reading. Expose the instrument to ambient dose equivalent rates from test sources of 0.1 iSv h1, 1 Sv h’, 10 pSv 1r1 and 80 % of stated upper limit and determine the response subtracting the mean background. Verify that the response for all exposures are within the stated requirement.
The test shall be performed with 24tAm, Cs and °Co reference sources.
6.5 Over range characteristics for ambient dose equivalent rate indication
6.5.1 RequIrements
The instrument shall indicate that an over range condition exists when the ambient dose equivalent rate Is greater than the manufacturer’s stated maximum ambient dose equivalent rate.