Radiation protection instrumentation - Installed dose rate meters, warning assemblies and monitors - X and gamma radiation of energy between 50 keV and 7 MeV
This International Standard applies to installed dose rate meters, warning assemblies and
monitors that are used to prevent or mitigate a minor radioactive release, or minor
degradation of fuel, within the nuclear power plants /nuclear facility design basis, and to warn
personnel or to ensure their safety during or following events that involve or result in release
of radioactivity in the nuclear power plants (NPP) /nuclear facility (NF), or risk of radiation
exposure. This equipment is typically classified as category “A” or “B” or “C” or “not classified”
in IEC 61226.
It covers equipment intended to isotropically measure air kerma, ambient dose equivalent or
other exposure quantities due to X or gamma radiation of energy between 50 keV and 7 MeV.
The equipment is intended primarily for the purpose of radiological protection, and may play
an auxiliary or indirect role in the achievement or maintenance of nuclear plant safety.
Instruments measuring over a more limited energy range fall within the scope of this standard
provided they cover at least the range of 80 keV to 1,5 MeV.
Assemblies of this type are commonly defined as area radiation monitors. They are normally
employed to determine continuously the radiological situation in working areas in which the
radiation field may change with time, for example nuclear power plants, particle accelerators,
high active laboratories, fuel reprocessing plants, and to provide alarms when the radiation
field goes outside predetermined limits. They are also employed to act in safety related
protection systems, such as personnel access control systems which allow access to areas
which can be subject to radiation fields.
This standard also gives guidance applicable to equipment for use in pulsed radiation fields,
for example, those emanating from pulsed radiation or particle accelerators. This guidance is
important, since the operation of the majority of the equipment defined by this standard in
pulsed fields will give false readings.
The assemblies considered in this standard comprise at least:
? a detector assembly (e.g, ionization chamber, Geiger-Muller tube, scintillation counters,
semiconductors);
? a measuring assembly, which may be fitted into a centralized panel which, in the case of
warning assemblies and monitors, provides signal outputs and contacts capable of
activating alarm or trip/interlock circuits for the purpose of radiation protection.
This standard is also applicable to installed dose rate measuring assemblies designed for
special applications (e.g. very high dose rates). However, some of the requirements may need
to be amended or supplemented according to the particular characteristics of such
assemblies.
This standard is not applicable to criticality monitors.
Assemblies designed to perform combined functions should comply with the requirements
pertaining to each of these functions.
This standard specifies general characteristics, general test procedures, radiation, electrical,
safety, and environmental characteristics and the identification certificate for the assemblies
defined above.