Radiation protection instrumentation – Neutron ambient dose equivalent (rate) meters
|Publication Date:||1 July 2014|
|ICS Code (Radiation protection):||13.280|
This International Standard is applicable to assemblies designed to measure the ambient dose equivalent (rate) due to neutron radiation in fields that contain neutrons with energies below 20 MeV, and which comprise at least:
a) a detection assembly, which may, for example, consist of a detector probe for thermal neutrons and an arrangement of neutron moderating and absorbing media surrounding the detector;
b) a measuring assembly with a display for the measured quantity, which may be incorporated into a single assembly with the detector or connected to it by means of a flexible cable.
Instruments with energy range up to 20 MeV are covered by this standard. If the instrument also provides indication of the neutron dose, it should meet the neutron dose requirements stated in this standard.
No tests are specified in this standard for performance requirements of assemblies in pulsed radiation fields. It is understood that an assembly designed to meet this standard may not be suitable for use in such fields.
The object of this standard is to specify requirements for the performance characteristics of neutron ambient dose equivalent (rate) meters, and to prescribe the methods of testing in order to determine compliance with this standard. This standard specifies general characteristics, general test procedures, radiation characteristics, electrical, mechanical, safety and environmental characteristics, and also the identification certificate (see 13.2). Requirements and test procedures are also specified for the alarm performance of the neutron ambient dose equivalent (rate) meters, equipped with alarm provisions.
NOTE The response of ambient dose equivalent (rate) meters for neutrons is energy dependent and may deviate considerably from unity. The response in realistic neutron fields, however, is such that the response deviations in different energy ranges tend to offset each other. Consequently, the response in realistic fields is generally much closer to unity.
ISO 12789 specifies a list of appropriate broad-spectrum neutron sources that are suitable for the testing of such (rate) meters. For example, simulated workplace neutron fields from ISO 12789 may be specified by agreement between manufacturer and purchaser to be appropriate for testing when the spectral environment is well defined.