IEC 62303:2008

IEC 62303
Edition 1.0 2008-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Radiation protection instrumentation – Equipment for monitoring airborne
tritium
Instrumentation pour la radioprotection – Matériel pour la surveillance du tritium
atmosphérique
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IEC 62303
Edition 1.0 2008-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Radiation protection instrumentation – Equipment for monitoring airborne
tritium
Instrumentation pour la radioprotection – Matériel pour la surveillance du tritium
atmosphérique
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
X
CODE PRIX
ICS 13.280 ISBN 978-2-88910-666-0
– 2 – 62303 © IEC:2008
CONTENTS
FOREWORD.4
1 Scope and object.6
2 Normative references .6
3 Terms and definitions .7
4 Classification of tritium monitoring equipment.11
4.1 General design considerations .12
4.2 Methods of detection .12
4.3 Ease of decontamination .12
4.4 Considerations for explosive mixtures .12
4.5 Corrosion resistance .12
4.6 Reliability .12
4.7 Capability of operational testing .12
4.8 Adjustment and maintenance facilities.13
4.9 Acoustic noise level of the assembly .13
4.10 Electromagnetic interference .13
4.11 Mechanical shock.13
4.12 Measurement characteristics .13
4.13 Measurement range .13
5 Equipment components .14
5.1 General .14
5.2 Sampling assembly .14
5.3 Detection assembly .16
5.4 Control assembly.16
5.5 Indication facilities.17
5.6 Alarm assembly.17
5.7 Check source .18
5.8 Ambient background shielding or compensation devices .18
5.9 Batteries.18
6 Test conditions .18
6.1 General test procedures .18
6.2 Tests performed under standard test conditions for normal operation
condition .19
6.3 Tests performed with variation of influence quantities.19
6.4 Tests performed under test conditions for emergency conditions .19
6.5 Types of sources.19
6.6 Metrological confirmation system during tests .20
7 Radiation detection tests .20
7.1 General .20
7.2 Reference response .20
7.3 Linearity .21
7.4 Response to other chemical forms of tritium .21
7.5 Response to radioactive gases other than tritium .22
7.6 Response time .22
7.7 Response to ambient gamma radiation.22
7.8 Response to neutron radiation.23
7.9 Overload test.23

62303 © IEC:2008 – 3 –
7.10 Repeatability .24
7.11 Stability of background indication .24
7.12 Reproducibility of the indication.24
8 Electrical and mechanical tests .25
8.1 Alarm trip range .25
8.2 Alarm trip stability .25
8.3 Equipment fault alarms.25
8.4 Warm-up time — detection and measurement assembly.25
8.5 Power supply variations.26
8.6 Battery test.26
8.7 Power supply transient effects.27
9 Air circuit performance test.27
9.1 General .27
9.2 Susceptibility to gaseous retention .28
9.3 Accuracy of the volume and flow rate measurement .28
9.4 Flow rate stability .29
9.5 Effect of filter pressure drop .29
9.6 Effect of power supply voltage on the flow rate.30
9.7 Effect of power supply frequency on flow rate.30
10 Environmental performance tests .30
10.1 Ambient temperature .30
10.2 Temperature shock.31
10.3 Relative humidity.31
10.4 Atmospheric pressure.32
10.5 Sealing.32
10.6 Mechanical shock.32
10.7 External electromagnetic immunity and electrostatic discharge .33
10.8 Electromagnetic emission.33
11 Type test report and certificate .33
12 Operation and maintenance manual .34
Annex A (informative) General information on conditions of operation.40
Annex B (informative) Preparation of tritiated radioactive reference sources.43

Figure B.1 – Calibration loop .44
Figure B.2 – Calibration loop with tritiated water vapours.45

Table 1 – Reference conditions and standard test conditions for normal operation
condition.35
Table 2 – Tests performed under standard test conditions for normal operation
condition.36
Table 3 – Tests performed with variation of influence quantities for normal operation
condition.37
Table 4 – Tests of air circuit.39

– 4 – 62303 © IEC:2008
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RADIATION PROTECTION INSTRUMENTATION –
EQUIPMENT FOR MONITORING
AIRBORNE TRITIUM
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62303 has been prepared by subcommittee 45B: Radiation
protection instrumentation, of IEC technical committee 45: Nuclear instrumentation.
This standard cancels and replaces the first edition of IEC 60710, published in 1981.
This standard directly complements IEC 60761-1 (2002) and IEC 60761-5 (2002).
The text of this standard is based on the following documents:
FDIS Report on voting
45B/593/FDIS 45B/599/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

62303 © IEC:2008 – 5 –
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 6 – 62303 © IEC:2008
RADIATION PROTECTION INSTRUMENTATION –
EQUIPMENT FOR MONITORING
AIRBORNE TRITIUM
1 Scope and object
This International Standard is applicable to equipment used for sampling and continuous
measurement of tritium in the workplace, in gaseous effluents discharged into the
environment as well as in the environment itself and it is applicable to installed, portable and
transportable equipment.
The object of this International Standard is to establish mandatory general requirements and
to present examples of acceptable methods and equipment for continuously monitoring and/or
sampling airborne tritium. The current standard IEC 60761-5 which is complemented by this
standard, is applicable to equipment for sampling and monitoring tritium only in gaseous
effluents, while this standard expands coverage to include monitoring all possible locations
where tritium could present a radiological hazard. The equipment is designed to be in
operation during normal operation conditions as well as under emergency conditions, both
during and following an accident. Depending of the emergency conditions, it might be
necessary to install specially designed equipment for normal operation conditions and other
equipment for emergency conditions.
This International Standard is applicable to tritium samplers and tritium monitors intended to
provide the following functions:
– the measurement of the volumetric activity of tritium and its variation with time in the
workplace, in gaseous effluents at the discharge point and in the environment;
– the actuation of an alarm when a predetermined volumetric tritium activity or tritium
concentration or a predetermined total activity of released tritium is exceeded;
– the determination of the total tritium activity discharged over a given time;
– the sampling and analysis of air or gas containing tritium.
This standard specifies the general characteristics, general testing procedures, mechanical,
electrical and electronic, radiological, safety and environmental characteristics, and the
proper identification and certification of the equipment. If this equipment is part of a
centralized system for continuous radiation monitoring in a nuclear facility, there may be
additional requirements from other standards related to those systems.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60050-393:2003, International Electrotechnical Vocabulary (IEV) – Part 393: Nuclear
instrumentation – Physical phenomena and basic concepts
IEC 60050-394:2007, International Electrotechnical Vocabulary (IEV) – Part 394: Nuclear
instrumentation – Instruments , systems, equipment and detectors
IEC 60068 (all parts), Environmental testing

62303 © IEC:2008 – 7 –
IEC 60068-2-27, Environmental testing – Part 2-27: Tests – Test Ea and guidance: Shock
(Basic safety publication)
IEC 60068-2-38, Environmental testing – Part 2-38: Tests – Test Z/AD:Composite
temperature/humidity cyclic test
IEC 60761-1, Equipment for continuous monitoring of radioactivity in gaseous effluents –
Part 1: General requirements
IEC 60761-5, Equipment for continuous monitoring of radioactivity in gaseous effluents –
Part 5: Specific requirements for tritium monitors
IEC 61000 (all parts), Electromagnetic compatibility (EMC)
IEC 61000-4-2, Electromagnetic compatibility (EMC) – Part 4-2: Testing and measurement
techniques – Electrostatic discharge immunity test
IEC 61000-4-3, Electromagnetic compatibility (EMC) – Part 4-3: Testing and measurement
techniques – Radiated, radio-frequency, electromagnetic field immunity test
IEC 61000-4-4, Electromagnetic compatibility (EMC) – Part 4-4: Testing and measurement
techniques – Electrical fast transient/burst immunity test
IEC 61000-4-5, Electromagnetic compatibility (EMC – Part 4-5: Testing and measurement
techniques – Surge immunity test
IEC 61000-4-11, Electromagnetic compatibility (EMC) – Part 4-11: Testing and measurement
techniques – Voltage dips, short interruptions and voltage variations immunity tests
IEC 61000-4-12, Electromagnetic compatibility (EMC) – Part 4-12: Testing and measurement
techniques – Ring wave immunity test
IEC 61000-6-4, Electromagnetic compatibility (EMC) – Part 6-4: Generic standards –
Emission standard for industrial environments
IEC 61000-6-6, Electromagnetic compatibility (EMC) – Part 6-6: Generic standards – HEMP
immunity for indoor equipment
IEC 61187:1993,Electrical and electronic measuring equipment – Documentation
ISO 2889 General principles for sampling airborne radioactive materials
ISO 10012:2003, Measurement management systems – Requirements for measurement
processes and measuring equipment
Guide to the expression of uncertainty in measurement (GUM), ISO, 1995
3 Terms and definitions
For the purposes of this document, the terms and definitions concerning detection and
measurement of ionizing radiation and nuclear instrumentation given in IEC 60050-393,
IEC 60050-394, as well as the following, apply.

– 8 – 62303 © IEC:2008
3.1
accident conditions
substantial deviations from operational states that are expected to be infrequent and which
could lead to release of unacceptable quantities of radioactive materials if the relevant
engineered safety features did not function as per design intent
3.2
alarm assembly
assembly or a combination of assemblies that provides audible or visual alarm output in the
event of an alarm threshold being exceeded or a malfunction being detected
3.3
anticipated operational occurrence
all operational processes deviating from normal operation which are expected to occur once
or several times during the operating life of the plant and which, in view of appropriate design
provisions, do not cause any significant damage to items important to nuclear safety nor lead
to accident conditions
3.4
coefficient of variation
the ratio V of the standard deviation s to the arithmetic mean x of a set of n measurements x
i
given by the following formula:
n
s 1 1
V = = ()x − x
∑ i
x x n − 1
i=1
3.5
control assembly
the assembly used to process the output of the detection assembly and provide indication and
power supply for the whole system
3.6
conventionally true activity
the best estimate of the activity of a radioactive source
NOTE Conventionally true activities are, in general, regarded as sufficiently close to the true value for the
difference to be insignificant for the given purpose. For example, a value and its uncertainty determined from a
primary or a secondary standard, or by a reference instrument which has been calibrated against a primary or
secondary standard, may be taken as the conventionally true value.
3.7
coverage factor
numerical factor (k) used as a multiplier of the combined standard uncertainty in order to
obtain an expanded uncertainty (GUM)
3.8
decision quantity
random variable for the decision whether the physical effect to be measured is present or not
3.9
decision threshold
fixed value of the decision quantity by which, when exceeded by the result of an actual
measurement of an measurand quantifying a physical effect, one decides that the physical
effect is present
NOTE The statistical test should be designed such that the probability of wrongly rejecting the hypothesis (error
of the first kind) is equal to a given value α. For this standard, α equals 5 %.

62303 © IEC:2008 – 9 –
3.10
design basis accident
set of accident conditions against which a facility is designed according to established design
criteria, and for which the damage to the nuclear fuel and the release of radioactive material
are kept within authorized limits
3.11
detection limit
smallest true value of the measurand which is detectable by the measuring method
NOTE The detection limit is the smallest true value of the measurand which is associated with the statistical test
and hypotheses (see decision threshold) by the following characteristics: if in reality the true value is equal or
exceeds the detection limit, the probability of wrongly not rejecting the hypothesis (error of the second kind) will be
at most equal to a given value β. For this standard, ß equals 5 %.
3.12
dynamic range
quotient of the signal from the maximum measurable indication of a quantity by the signal
from the decision threshold of that quantity
3.13
effective range of measurement
range of the values of the activity to be measured over which the performance of a piece of
equipment or an assembly meets the requirements of its specifications
3.14
error of indication
difference between the indicated value v of a quantity and the conventionally true value v of
c
that quantity at the point of measurement
Δν =ν −ν
c
where
ν is the value of the quantity indicated by the equipment or assembly under test;

ν is the conventionally true value of the quantity
c
3.15
manufacturer
the term "manufacturer" includes the designer and the seller of the equipment
3.16
measurement assembly
this assembly includes functional units designed to measure quantities related to ionizing
radiation (activity, volumetric activity, etc.)
3.17
measurement uncertainty
parameter, associated with the result of a measurement, that characterises the dispersion of
the values that could reasonably be attributed to the measurand. Any result of a measurement
should be given with the associated uncertainty calculated following the method
recommended in the GUM
3.18
normal operation
operation of a nuclear facility within specified operational limits and conditions
3.19
purchaser
the term "purchaser" includes the user

– 10 – 62303 © IEC:2008
3.20
radiation detection assembly
assembly designed to produce a signal in response to incident ionising radiation
NOTE 1 This signal carries information about physical properties of the radiation.
NOTE 2 One or more sub-assemblies may be included in the same unit.
3.21
reference response
response of the assembly under reference conditions to a reference volumetric activity. This
reference response is expressed as:
V
R =
ref
V
c
where
ν is the value measured by the the equipment or assembly under test; and

ν is the conventionally true value of the reference source.
c
NOTE The background value may be automatically taken in account by an algorithm included in the measuring
system.
3.22
relative error
error of the measurement divided by a true value of the measurand
NOTE Since a true value cannot be determined, in practise a conventionally true value is used.
3.23
response time (of a measuring assembly)
duration between the instant of a step change in the measured quantity and the instant when
the output signal reaches for the first time as specified percentage of its final value, that
percentage being usually taken as 90 %
NOTE For this standard, 90 % is used.
3.24
retention capacity
the maximum quantity of a defined substance which can be retained at equilibrium in the
medium considered
3.25
sampling assembly
set of connected devices used to collect a representative sample
3.26
sampling collection efficiency
for a given quantity of radioactive material, ratio of the collected activity to the supplied
activity, for a specified time interval
3.27
sensitivity
for a given value of the measured quantity, ratio of the variation of the observed variable to
the corresponding variation of the measured quantity

62303 © IEC:2008 – 11 –
3.28
severe accident
set of accident conditions more severe than those of a design basis accident and involving
significant core degradation
3.29
tritium
unless otherwise stated, ”tritium”, in this standard, covers tritium in gaseous or vapour forms,
whether chemically combined or not
3.30
tritium monitor
equipment designed for the monitoring of airborne tritium in gaseous effluent discharged to
the environment, in the environment and in the atmosphere of a workplace.
3.31
tritium sampler
equipment designed to collect a sample of tritium in any form for subsequent analysis.
3.32
volumetric activity
quotient of the activity by the total volume of the sample
NOTE 1 For a gas, it is necessary to indicate the temperature and pressure conditions for which the volumetric
activity, expressed in becquerels per cubic metre, is measured, for example standard temperature and pressure
(STP).
NOTE 2 This quantity is expressed in becquerels per cubic metre (Bq/m ).
4 Classification of tritium monitoring equipment
Various tritium monitor designs are available to meet the specific needs of the user. This
standard classifies tritium monitors based on the following operational and usage
requirements:
• Selectivity for the chemical form of tritium:
– gross tritium monitors respond to all gaseous or vapour forms of tritium;
– selective tritium monitors are designed to detect a specific chemical form of airborne
tritium, for example tritiated water vapour.
• Method of sampling and analysis:
– flow-through methods in which air is drawn through a measuring device with
simultaneous detection;
– batch (sequential) methods in which tritium is collected on an adsorber or trap to allow
detection.
• Measurement range:
– low range tritium monitors include those monitors that can be used to measure
volumetric activity up to 10 MBq/m ;
– high range monitors are those monitors that can be used to measure volumetric
activity in excess of 10 MBq/m .
• Working condition:
– normal operation conditions;
– emergency conditions.
• System interface:
– local readout and alarm only;

– 12 – 62303 © IEC:2008
– interfaced with a centralized system to initiate alarms or indicate operating faults in
addition to the local readout and alarm indications.
• Type of installation and/or power source:
– installed or transportable tritium monitors primarily operate using mains power, and
may have battery backup. Installed monitors typically have outputs that interface the
monitor with a centralized radiation monitoring system;
– portable monitors primarily use battery power and are typically carried from location to
location for use. They can also use line power through an internal or external
converter, and can also have the ability to interface with a centralized system.
4.1 General design considerations
4.2 Methods of detection
This standard does not specify what type or types of radiation detectors may be used to
accomplish the performance required.
4.3 Ease of decontamination
Surfaces that are designed to come in contact with radioactivity (e.g., the sampling and
detection assemblies) shall be constructed in such a manner that the build-up of
contamination is minimized and shall be designed to facilitate decontamination or to make
components easily replaceable.
4.4 Considerations for explosive mixtures
In some circumstances, the measured sample may contain an explosive mixture of gases.
Where an explosive mixture may exist, the assembly shall be designed to prevent the ignition
of the sample.
4.5 Corrosion resistance
Special system designs shall be required to protect sampling and measuring systems from
noxious and/or corrosive substances.
4.6 Reliability
All equipment shall be designed to provide reliable performance with unexplained failures kept
to a practical minimum.
The manufacturer should provide documentation on the expected operational lifetime of
critical components such as, the air pump, the detector, the flow rate measuring device, the
batteries etc.
The manufacturer shall specify the frequency of routine maintenance, and fully describe each
maintenance procedure. These maintenance requirements should be kept to a practical
minimum.
4.7 Capability of operational testing
The purchaser should be provided with the capability to carry out periodic checks for
satisfactory operations of the assembly, including calibration and verification of the
measurement linearity. These testing components should normally be installed so as to allow
the checks to be carried out with the control and measurement assembly.
It shall be possible to check the calibration of the assembly at two representative points on
the measurement range.
62303 © IEC:2008 – 13 –
This check shall be carried out using one or more suitable radioactive sources, as necessary.
The measurement linearity may be checked electronically.
4.8 Adjustment and maintenance facilities
All electronic equipment shall have a sufficient number of easily accessible identified test
points to facilitate adjustments and fault location. Any special maintenance tools, together
with an appropriate maintenance manual shall be supplied.
The design of all equipment shall be such as to facilitate ease of repair and maintenance.
Self-diagnostic features should be available with a display.
4.9 Acoustic noise level of the assembly
Acoustic noise level of the assembly mainly arises from the sampling assembly and more
particularly from the operation of the fluid duct system and the resultant vibration.
The manufacturer shall select the components and shall design the assembly so that the
acoustic noise level is minimized and consistent with the type of environment for which the
assembly is intended.
4.10 Electromagnetic interference
All necessary precautions shall be taken to protect the equipment from the effects of
electromagnetic interference either received or emitted by the equipment.
The severity level 3 shall be applied for immunity (IEC 61000 series).
The manufacturer shall specify the electromagnetic emission of the equipment. The emission
limits for apparatus covered by this standard are given in Table 1 of the IEC 61000-6-6.
4.11 Mechanical shock
The monitor should be designed to minimize the effects of mechanical shock.
4.12 Measurement characteristics
The electronic assembly should indicate the measured activity in Bq/m . Other methods of
indication shall be used by agreement between the manufacturer and the purchaser
The manufacturer shall indicate the decision threshold and the effective range of
measurement of the equipment. These characteristics shall be described taking into account
the reference background level (0,2 μGy/h) and volumetric activity of radon.
4.13 Measurement range
The effective range of the measurement shall be appropriate to the particular application. The
lowest detectable concentration for emergency condition tritium monitors shall at least overlap
the highest decade of a tritium monitor designed for normal operation conditions.
The highest detectable concentration shall be at least 0,5 decade above the concentration
expected during emergency conditions.
The values of the lowest and highest concentration to be monitored shall be agreed upon
between the purchaser and the manufacturer.

– 14 – 62303 © IEC:2008
5 Equipment components
5.1 General
The equipment comprises several components. The main components and their functions are
mentioned and described in the following subclauses.
5.2 Sampling assembly
5.2.1 General
The sampling assembly includes essentially one or more of the following assemblies and
functional units:
– sampling and exhaust pipes;
– facility for drawing samples for laboratory analysis and for calibration tests with tritium;
– air/counting gas mixing device (for proportional counters);
– air/liquid scintillation mixing device (for liquid scintillation counters);
– measuring chamber and/or sample cell;
– ambient gamma radiation protection device and/or compensation device or adequate
shielding;
– airborne particulate retention device, where appropriate;
– individual air pump or centralized pumping station;
– air flow rate monitoring and/or control devices, where appropriate;
– pressure monitoring and/or control device, where appropriate;
– humidity monitoring and/or control device, where appropriate;
– temperature measuring device, where appropriate;
– batteries, where appropriate.
5.2.2 Sampling and exhaust pipes
The following characteristics shall be considered and shall be agreed upon between the
manufacturer and the purchaser:
– the material being used, with particular attention being given to chemical corrosion,
surface adsorption, memory effects, etc.;
– the minimum distance between inlet and outlet to avoid recirculation;
– the prevention of condensation in the pipe by control of temperature and/or pressure;
– the impacts of flow rate and pressure drop on the measurement;
– the delay time to detector (flow rate, pipe diameter, length of the sampling pipes);
– the ease of decontamination.
5.2.3 Inlet filter
A filter shall be placed in a filter-holder at the sampling circuit inlet to remove any dust and
aerosols from the air. In order to maintain the specified performance of the equipment, such a
filter shall not trap, or even temporarily retain tritium. To ensure that the inlet filter does not
retain tritium or to observe the retained tritium by the calculation of the tritium activity the
filter-holder shall be removable without loss of radioactive material sticking to the filter.
All necessary arrangements shall be made to control the pressure drop in the filter. The
system should be designed with an alarm facility indicating a significant pressure change
which may have resulted from a faulty filter. It shall be possible to change the filter easily.

62303 © IEC:2008 – 15 –
5.2.4 Collection medium
If the detection assembly includes a collection medium intended to collect a specific chemical
form of tritium or to concentrate the activity, its characteristics efficiency, retention capacity
and delay time constant - shall be known for the appropriate form of tritium.
The manufacturer shall specify how the collection efficiency and the collection capability are
influenced by the chemical form of tritium, the sampling flow rate, the tritium concentration,
atmospheric conditions and the presence of chemical products and other gases in air
sampled. The manufacturer shall indicate how a purchaser can recognise that the collection
efficiency or the collection capacity have deteriorated to become unacceptable. The
manufacturer shall specify the conditions of storage of the collection medium.
5.2.5 Air pump
Where a pump is an integral part of any assembly, the following requirements shall be met:
– the pump shall be placed downstream of the detection assembly. An exception is when the
measurement is made by collecting the tritium in a pressurised chamber;
– the design shall provide for ease of access to the pump and its replaceable parts;
– the nominal flow rate shall be stated by the manufacturer;
– the model of pump and its replaceable parts shall be specified;
– the pump and its replaceable parts shall be easily replaceable;
– the pump shall provide an air flow at a rate that is adequate for the measurement method;
– where the measurement technique of volumetric activity is sensitive to pressure, care
should be taken to ensure that the pressure in the measuring volume is only slightly
affected by the variation of pressure drop across the inlet filter;
– care shall be taken to prevent radioactive gases from leaking into the breathing zone of
workers;
– the pumps of a monitoring system and the sampling units designed to be operational
during and after an accident shall be gas tight. The acceptable leak rate depends on the
accident conditions. The manufacturer and the purchaser shall agree upon the leak rate of
a pump of a measuring device to be in operation during and after a design basis accident
or a severe accident and upon the conditions to be used whilst the monitors are in
operation;
– the pump shall be capable of
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