BS 7518:1995 Radiation protection instrumentation. Portable, transportable or installed equipment to measure x or gamma radiation for environmental monitoring. Integrating assemblies
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Irradiation of members of the public from external
radiation produced by nuclear and other
establishments is subject to control, and an
essential part of control is measurement of the
environmental radiation levels in the
neighbourhood of these establishments1)
.
The evaluation of the environmental air kerma
from X and gamma radiation is difficult. The
composition of the background air kerma is
complex, with contributions from natural sources
such as cosmic radiation and terrestrial
radioactivity as well as from man-made
radioactivity arising from the operation of nuclear
facilities and fall-out from nuclear weapons tests.
Furthermore, the natural background air kerma
rate varies in time and space.
This part of IEC 1017 defines performance
parameters for portable or installed integrating
assemblies to measure the environmental air
kerma. If regulations require other dose or exposure
quantities to be used for the above purposes (for
example, ambient dose equivalent), this standard
may be applied to the performance characteristics of
equipment to measure these other quantities. For
example, the same numerical values for the
requirements for the radiation characteristics
would still apply, but the conventionally true values
would be expressed in the other quantities (for
example, ambient dose equivalent) and not in air
kerma.
It is assumed in this standard that the term “air
kerma” means the kerma to air at a point in the
environmental radiation field which may include
scattered radiation and that the radiation detector
has a wall thick enough to give electron equilibrium.
This standard applies to portable or installed
integrating assemblies intended to measure
environmental air kerma due to X or gamma
radiation of energy between 50 keV and 1,5 MeV2)
from 10 nGy up to 10 mGy (1 4rad up to 1 rad) by
integration of the detector’s signal, i.e. integration of
pulse count rate, ionization current, etc. Passive
devices such as film dosemeters or TLD are not
covered by this standard. If the assembly is to be
used to measure air kerma in the area surrounding
a nuclear power station when 6 MeV radiation is
present, it will be necessary to determine the
response at this energy.
For the purpose of radiation protection, these
assemblies comprise at least:
— a detection sub-assembly (for example,
ionization chamber, GM counter tube,
scintillation detector, etc.);
— a measuring sub-assembly including a display
device, which may be connected to the detector
sub-assembly either rigidly or by means of a
flexible cable, or incorporated into a single
assembly. The installed assembly may also
comprise a continuous recorder (for example,
chart or magnetic cassette recorder or telemetry
equipment).
This standard specifies, for the assemblies
described above, general characteristics, general
test procedures, radiation characteristics, electrical,
mechanical, safety and environmental
characteristics and also the identification
certificate.
This standard does not provide for the measurement
of beta radiation.
BS 7518:1995 Radiation protection instrumentation. Portable, transportable or installed equipment to measure x or gamma radiation for environmental monitoring. Integrating assemblies
