IEC 62484-2020 pdf free download

IEC 62484-2020 pdf free download.Radiation protection instrumentation — Spectrometric radiation portal monitors (SRPMs) used for the detection and identification of illicit trafficking of radioactive material.
The value of 12 % is chosen to help determine the results of a test as the series of readings and the associated mean are compared to a requirement set in this document. Processes such as increasing the applied radiation levels will typically reduce the CCV to an acceptable level. The number of trials or readings may also be increased to reduce the CCV, but this should be secondary to increasing the applied radiation level. When testing without the presence of radioactive sources, the SRPM is observed so it does not produce alarms and/or spurious indications. In this case the CCV value is not relevant.
The time interval between each reading shall be long enough to ensure that the readings are independent. The time interval selected is dependent on the integration time of the SRPM and the update time of the indicated response.
5.2 Reference neutron radiation for alarm testing
252Cf or 244Cm shall be used as the neutron test source. The source shall have a neutron emission rate of 20 000 ns1 (-0 %, +20 %) and be surrounded by a high-density polyethylene (0,93 gcm3 to 0,97 gcm3) moderator. The moderator shall be surrounded by wall(s) that have a thickness of 4 cm with the source place not farther than 1,5 cm from each wall. The standard uncertainty in the neutron emission rate shall be less than or equal to 10 % (k=1).
NOTE I The activity level is for testing only and is not indicative of the neutron alarm set point or overall neutron detection capability of an SRPM.
NOTE 2 Due to radioactive decay, the 252Cf source will be within the stated range of 20 000 ns1 to 24 000 ns1 for only 8 months. For 244Cm, the usage time will be approximately 4.7 years.
5.3 Alarm categorization
Alarms may be categorized based on the level of radiation detected and measured, and the identification results. The International Atomic Energy Agency (IAEA) has recommended a method of categorization (IAEA-TECDOC-1 311, September 2002).IEC 62484-2020 pdf free download.