detect and identify
Revision of IEC 61005
Neutron ambient dose equivalent meters
Alfred Klett
Berthold Technologies, Bad Wildbad Germany
Neutron Users Club Meeting
NPL/Teddington, November 1, 2011
History of Standard IEC 61005
Radiation protection instrumentation – Neutron
ambient dose equivalent (rate) meters prepared by
IEC technical committee 45: Nuclear instrumentation
subcommittee 45B: Radiation protection instrumentation
working group B8 Active Electronic Dose Equivalent and
Dose Equivalent Rate Meters and Monitors
current project leader: Radoslav Radev / LLNL
IEC 61005 1st edition
IEC 61005 2nd edition
IEC 61005 3rd edition (CD)
Alfred Klett Nov 1, 2011
1990-09
2003-02
2011-11
2
IEC 61005 Revision Documents & Plan
Document ID
45B/684/RR
45B/685/CD
45B/685/CC_MV
Title
Date
Review Report (RR)
2011-02-18
Committee Draft (CD) 2011-02-18
Comments (CC)
2011-05-16
Schedule
Committee Draft for Vote (CDV)
Final Draft International Standard (FDIS)
Publication of International Standard
Alfred Klett Nov 1, 2011
2013-02
2014-02
2014-06
3
Scope
assemblies for the measurement of ambient dose
equivalent for neutrons up to 20 MeV, comprising:
detection assembly (for example thermal neutron
detector with neutron moderator/absorber)
measuring assembly (display reading)
not applicable to unconventional dose meters as
spectroscopic neutron dose meters (more than 1 probe)
meters based on bubble dosimeter technology
meters based on silicon pillar neutron detectors
electronic personal dose (rate) meters
No requirements for pulsed radiation fields defined
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Normative references
Electromagnetic compatibility (EMC)
IEC
IEC
IEC
IEC
IEC
IEC
IEC
61000-4-2:1995
61000-4-3:2002
61000-4-4:1995
61000-4-5:1995
61000-4-6:1996
61000-4-8:1993
61000-4-12:1995
ISO 8529 Reference neutron radiations
ISO 8529-1:2001 Characteristics and methods of production.
ISO 8529-2:2000 Calibration fundamentals
ISO 8529-3:1998 Calibration and determination of response
ISO 11929:2010 Determination of the characteristic limits
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Tests
Tests for influence quantities of
Type F
Type S
Radiation sources
241Am-Be, 252Cf
241Am-Be, 252Cf
moderated by D2O sphere ∅ 30cm
accelerator target sources (ISO 8529)
for thermal & epithermal reference fields, accelerator
target, reactor beams, 241Am-Be or 252Cf sources with well
defined moderator/filter arrangements may be used
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Radiation sources for tests
241Am-Be, 252Cf
bare
241Am-Be, 252Cf moderated by D O sphere ∅ 30cm
2
accelerator target sources (ISO 8529)
for thermal & epithermal ref. fields, accelerator
target, reactor beams, 241Am-Be or 252Cf sources
with well defined moderator/filter arrangements
Work place neutron fields
simulated fields specified in ISO 12789
other work place environments whose fields are well defined
by spectral calculations and/or measurements traceable to
or recognized by a primary standards laboratory
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General requirements: effective range
For dose meters with an analogue display: omitted here
for dose meters with a digital display, from an indication in the
2nd least significant digit up to the maximum indication on each
range. (example: with max. indication 9 999,9, the effective
range can extend from 1,0 to 9 999,9)
for dose meters with digital & scientific display the mantissa
shall have 3 digits at least (for instance 1,00 to 9,99). The
manufacturer shall define the effective range of measurement
(for instance 1,00 E–7 to 9,99 E–2 Sv h–1).
The minimum effective range of measurement of
dose equivalent rate: at least 4 orders of magnitude including 10 µSv h–1
dose equivalent: at least 4 orders of magnitude including 0,1 mSv.
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General requirements
Mechanical characteristics
assembly labels shall include
measured quantity
effective range of measurement
the type of radiation the dose meter is suitable for
rated range of particle energy
reference point & orientation (or in the manual)
IP classification shall be stated by the
manufacturer according to IEC 60529
Ease of decontamination
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General requirements
Interface requirements
output connection for a remote readout is
recommended
recommended input and output connections
input connection to the pre-amplifier input
for electrical test purposes
output connection from the amplifier
output connection from the discriminator
manufacturer shall deliver the evaluation algorithm
of the indicated value
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Radiation detection requirements
indication of the assembly shall be in units of
ambient dose equivalent (rate), for example in
millisieverts (per hour)
variation of relative response due to the nonconstancy of the dose rate response shall not
exceed –17 % to +25 % over the whole of the
effective range of measurement for neutron
reference radiations chosen
The statistical fluctuations of the indication
measured as coefficient of variation shall fulfill the
requirements given in Table 3.
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it is permissible to employ an equivalent electrical
test in order to determine the intrinsic error at the
ambient dose equivalent rates that cannot be
provided by the sources of radiation.
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Variation of the response due to neutron
radiation energy and angle of incidence
Combination of requirements for angular and energy response
was intended (like for instance IEC 60841-1:2009)
But it was unclear if any existing instrument could meet these
requirements they are now independent in the CD
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Variation of response due to neutron energy
“it would be desirable for the variation of the
response with the neutron energy over the whole
energy range from thermal to the maximum
energy specified by the manufacturer not to
exceed 50%. However, at the time of publication,
such requirement is not practically achievable”
(6.4.1)
appropriate response calculations, the results of
these calculations shall be made available for the
entire energy range with data at least at two
energy points per decade of radiation energy.
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Neutron Survey Instruments
International Atomic Energy Agency IAEA, Technical Reports
Series No. 403, Compendium of Neutron Spectra and Detector
Responses for Radiation Protection Purposes, Supplement to
Technical Report Series No. 318, Vienna, 2001, Table 3.II. p. 27
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Energy Dependent Dose Response Rem-Counters
Calculated
from the data
of IAEA TRS 418
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Variation of response due to neutron energy
Energy Range
Requirements
thermal - 50 keV
manufacturer shall specify variation of
ambient dose equivalent with neutron
energy. The recommended variation
should not be more than 20%-800%
50 keV - 10 MeV
within 50%-150% of response for 0°
incident radiation and reference energy
10 MeV – max. Energy
manufacturer shall specify variation of
ambient dose equivalent with neutron
energy. The recommended variation
should not be more than 20%-100%
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Method of test of energy response
at least at two neutron energies below 50 keV
or with a moderated source
at least at three neutron energies in the energy
range between 50 keV and 10 MeV
at least with 1 broad source (e.g. 252Cf or 241Am-Be)
at least at one neutron energy exceeding 10 MeV
only tests at energies within the manufacturer’s
specified energy range are required
In addition, it is recommended to state response to
standardized simulated work place neutron fields
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Dose & dose rate alarm requirements
when the dose equivalent (rate) meter is
subjected to a dose equivalent (rate) of 0,8 of the
dose equivalent (rate) alarm set point for 10 min,
the alarm shall not be activated
Similarly, at a dose equivalent (rate) of 1,2 times
the alarm level set, the alarm shall be activated
the alarm shall actuate within 5 s or within a time
such that the product of this time and the dose
equivalent rate of the alarm point is less than 10
µSv
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Additivity of indicated value requirements
The indicated value shall be additive
with respect to simultaneous irradiation with
different types of radiation (for example,
photon and neutron)
and with different neutron energies
and with different angles of radiation
incidence
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Test additivity of indicated value
Perform subsequently two irradiations under the
two different irradiation conditions K and L
(different energies, different angles of incidence or
even different types of radiations) with the
conventional quantity values HK and HL
Determine the indicated values GK and GL for the
two irradiations.
Then perform a third simultaneous irradiation
under the two irradiation conditions K and L with
the conventional quantity value HK+L = HK + HL
and determine the indicated value GK+L
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Test additivity of indicated value
shall be determined for any value of HK and HL and
any simultaneous combination of radiation fields
SK and SL
As simultaneous irradiations are very difficult to
perform, the use of calculations as a replacement
for the simultaneous irradiations is permitted and
recommended for this test
∆gmix shall be lower than 0.1
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Variation of angular response
The response values shall be measured
for polar angles of incidence of α = 0°, ±45°, ±90°
for azimuth angles β of 0°, 90°, 180°, 270°, 360°
while keeping α = 0°
measurements shall be performed at one
monoenergetic or one broad neutron spectrum.
Test distance should be at least 3 times the sum of
the largest linear dimension of source & detector
The scatter contribution to the indicated value of
the device shall not exceed 20 % (ISO 8529-2).
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Overload characteristics
The dose equivalent meter shall read off-scale
on the high side or shall indicate overload when
exposed to doses greater than the maximum of
its measuring range
When subjected to dose rates high enough to
cause wrong dose indication, there shall be
indication that the equipment is not able to
provide correct dose indication
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Overload chracteristics test ?!? CHECK
Subject the dosemeter to a dose in excess of
10 times the maximum dose that can be indicated,
at most 50 Sv, at least 1 Sv.
Dose rate during exposure shall be less than the
maximum dose rate capability as specified by the
manufacturer. The equipment shall not be reset or
switched off for at least 30 min after the
equipment has been subjected to the test dose.
Subject the dose equivalent meter to a dose rate
10 % in excess of that specified as the dose rate
limit by the manufacturer for a period of 100 s. In
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case, no error of the dose
Response time
30 s for the increases or decreases of the ambient
dose equivalent rate less than 0,1 mSv⋅h–1
10 s for the increases or decreases of the ambient
dose equivalent rate between 0,1 mSv⋅h1and 1
mSv⋅h–1;
4 s for the increases or decreases of the ambient
dose equivalent rate greater than 1 mSv⋅h–1.
The manufacturer shall state the response time.
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Response time
for the increases or decreases of the ambient dose
equivalent rate
30 s for less than 0,1 mSv⋅h–1
10 s between 0,1 mSv⋅h1and 1 mSv⋅h–1;
4 s for greater than 1 mSv⋅h–1.
The manufacturer shall state the response time
Definition
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Response time tests
The test may be carried out either with a suitable
neutron source or by the injection of a suitable
electrical signal
The initial and final ambient dose equivalent rates
shall differ by a factor of at least 10 and
measurements shall be carried out for both an
increase and a decrease in the ambient dose
equivalent rate by this factor
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Variation of the dose response due to
dose rate dependence - Requirements
The variation of the relative dose response due to
dose rate dependence shall not exceed the range
from –13 % to +18 %
In addition, the variation of the rel. response due
to low dose rates down to natural environmental
radiation shall be stated by the manufacturer
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Test of variation of the dose response
due to dose rate dependence
Determine dose responses at 80 % of each order of magnitude
of the effective dose range when meter is exposed to a source
Perform the test for each dose at one dose rate of each order
of magnitude of the rated range of use for dose rate
Since at lower dose values, the exposure times are too short,
whilst at high dose values, the exposure times are too long for
the lower rates, these tests shall exclude any exposure involving measurement times less than 10 s or in excess of 10 h
The variation of the relative dose response due to dose rate
dependence shall not exceed the range from –13 % to +18 %
If integration is done digitally a test of ≈100 s per dose rate is
sufficient.
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Dose equivalent rate alarm requirements
when the dose meter is subjected to 0,8 of the
dose equivalent rate alarm set point for 10 min the
alarm shall not be activated for more than 10% of
the period of test
Similarly, at a dose equivalent rate of 1,2 times
the alarm level set, the alarm shall be activated for
90% of the test period.
alarm shall actuate within 5 s or within a time such
that the product of this time and the dose equivalent rate of the alarm point is less than 10 µSv
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Dose equivalent alarm requirements
when the dose equivalent meter is subjected to a
dose equivalent of 0,8 times the dose equivalent
alarm set, no alarm shall be given
when the dose equivalent meter is subject to a
dose equivalent rate of 1,2 times the dose
equivalent alarm set point, the alarm shall be
actuated.
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Response to photon radiation Requirements
Photon response shall be quoted in terms of units
of the photon ambient dose equivalent rate
Photons may not only cause the assembly to give an
indication, but it may also modify the response to
neutron radiation. Therefore, there are two separate
requirements
Indication to 137Cs photons at 10 mSv⋅h–1 shall not
exceed indication of 0,1 mSv⋅h–1 neutron
high-energy photon radiation (6 MeV) response shall,
by agreement between the manufacturer and the
purchaser, be checked at higher energies
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Test of response to photon radiation
assembly shall be exposed to a 137Cs source in
a field having an ambient dose equivalent rate
of 10 mSv⋅h–1
indicated value shall not exceed 0,1 mSv⋅h–1
Radiation sources used shall conform with the
ISO 4037 series
indication produced by a 137Cs and higher energy
(> 1.5 MeV) photon dose rate of 10 mSv⋅h–1 is less
than the indicated value due to a neutron ambient
dose equivalent rate of 0,1 mSv⋅h–1
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Additivity of indicated value
The indicated value shall be additive with respect to
simultaneous irradiation with
different types of radiation (f. e. photon and neutron)
different neutron energies and angles of incidence
If dosemeter uses
only one signal (measured with one detector) for
evaluation, then this is fulfilled
more than one signal (measured either with several
detectors or with one detector using for example pulse
height analysis), then this is not automatically fulfilled
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Additivity of indicated value
In that case, it shall be assured that the relative
change in indication,mixg∆, caused by the mix of
radiation shall not exceed ± 0,1
NOTE If the algorithm used to evaluate the indicated
value, (see 5.5) is either a linear combination of the
signals or a linear optimization of them, then this
requirement is fulfilled or no tests are required
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Other Requirements
Environmental
Temperature
Temperature shock
Humidity
Mechanical Requirements
Mechanical shock
Drop Test
Vibration Test
Electromagnetic Requirements
Documentation
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References
ICRU The International Commission on Radiation Units and
Measurements, Fundamental Quantities and Units for Ionizing
Radiation, ICRU Report 60, ICRU Publications, Bethesda, MD, 1998
ICRU The International Commission on Radiation Units and
Measurements, Determination of Operational Dose Equivalent
Quantities for Neutrons, ICRU Report 66, Journal of the ICRU, Vol. 1
No. 3, 2001
IAEA Compendium of Neutron Spectra and Detector Responses for
Radiation Protection Purposes, Technical Reports Series No. 318,
International Atomic Energy Agency, Vienna, 1990
IAEA Compendium of Neutron Spectra and Detector Responses for
Radiation Protection Purposes, Supplement to Technical Reports
Series No. 318, Technical Reports Series No. 403, International
Atomic Energy Agency, Vienna, 2001
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References
R.J. Tanner, C. Molinos, N.J. Roberts, D.T. Bartlett, L.G. Hager, L.N.
Jones, G.C. Taylor, D.J. Thomas, Practical Implications of Neutron
Survey Instrument Performance Report HPA-RPD-016 , Nov. 2006,
Health Protection Agency, Chilton, Didcot, United Kingdom
ICRP The International Commission on Radiological Protection,
Conversion Coefficients for use in Radiological Protection against
External Radiation Publication 74, Annals of the ICRP, Vol. 26, No.
3-4, 1996
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