Czech Metrology Institute  
Okružní 31, 638 00  Brno  
 
1. ------IND- 2018 0590 CZ - EN- ------ 20181217 --- --- PROJET 
'Measuring instruments used to monitor activity limits and concentration of emissions from nuclear 
facilities, nuclear raw material mining or processing facilities, radioactive waste processing  plants 
and from the processing or application of radioactive materials, and also used to determine 
environmental radiation exposure due to emissions – measuring instruments for continuous 
monitoring of radioactive noble gases in gas emissions from nuclear  facilities ' – may be placed on the 
market and put into use in the Czech Republic as specified measuring instruments  pursuant to Act 
No 505/1990 on metrology, as amended.Pursuant to this act, the specified measuring instruments are 
measuring instruments in  the List of Specified Measuring Device Types (Decree No 345/2002) and 
specified (by the manufacturer/importer) for measurement with significance for protection of the 
public interest in the following areas: consumer protection; contractual relations; stip ulation of 
sanctions, fees, tariffs and duties; health protection; environmental protection; occupational safety or 
protection of other public interests protected by separate legislation .This is therefore a similar purpose 
as that which is used to identify  stipulated products – non-automatic measuring and weighing 
instruments pursuant to Directives 2014/31/EU and 2014/32/EU.The requirements of this legislation 
do not apply to measuring instruments not placed on the market in the Czech Republic for the above  
purposes, identified by Act No 505/1990 on metrology.  
The purpose of this notified legislation is to lay down metrological and technical requirements for 
these specified measuring instruments.This legislation also stipulates tests for type approval and 
verification of specified measuring instruments of this type.  
(End of executive summary)  
 
Author:Mgr.Tomáš Hendrych  
Telephone:+420 545 555 414  
 
 
P U B L I C  N O T I C E 
 
As the authority with substantive and territorial jurisdiction in the matter of laying down metrological 
and technical requirements for specified measuring instruments and stipulating the testing methods for 
type approval and verification of specified measuring instruments pursuant to §  14(1) of Act 
No 505/1990, on metrology, as amended (her einafter the ‘Metrology Act ’), and in accordance with the 
provisions of §  172 et seq. of Act No  500/2004, the Code of Administrative Procedure (hereinafter the 
‘CAP ’), the Czech Metrology Institute (hereinafter the ‘CMI ’) commenced ex officio proceedings o n 
26 2.2016 pursuant to §  46 of the CAP, and, based on supporting documents, issues the following:  
 
I. 
D R A F T   G E N E R A L  M  E A S U R E 
number:0111 -OOP -C076 -16 
laying down the metrological and technical requirements for specified measuring 
instrume nts, including testing methods for verification of the following specified measuring 
instruments:  General Measure No 0111 -OOP -C076 -16 
2  
‘measuring instruments used to monitor activity limits and concentration of emissions 
from nuclear facilities, nuclear raw material mining or processing faci lities, 
radioactive waste processing plants and from the processing or application of 
radioactive materials, and also used to determine environmental radiation exposure 
due to emissions – measuring instruments for continuous monitoring of radioactive 
noble  gases in gas emissions from nuclear facilities ’ 
 
This legislation stipulates metrological and technical requirements for measuring instruments for 
continuous monitoring of radioactive noble gases in gas emissions from nuclear facilities.  
1 Basic definitio ns 
For the purposes of this general measure, terms and definitions pursuant to VIM and VIML1 as well as 
the terms and definitions stated below apply.  
1.1 
gas emission monitor  
an apparatus intended for continuous monitoring of radioactivity in gas emissions ; individual parts of 
the apparatus may be connected into two separate pieces of equipment that may be connected or 
separated according to monitoring and operating requirements  
 
1.2 
noble gas monitor  
a device for continuous monitoring of radioactive noble gases in emissions released into the 
environment  
1.3 
radioactive noble gases  
radionuclides 133Xe, 135Xe, 85Kr, 41Ar 
1.4 
detection apparatus  
includes one or more radiation detectors and related functional units  
 
1.5 
control and evaluation apparatus  
contains  apparatus and functional units for measuring quantities related to ionising radiation (activity, 
activity concentration, etc.); the apparatus has functional units providing clear warnings that the 
measured quantity has exceeded a pre -set value  
                                                      
1  TNI 01 0115 International Vocabulary of Metrology – Basic and General Concepts and Associated Terms 
(VIM) and International Vocabulary of Legal Metrology (VIML) are part of the technical harmonisation 
compendium ‘Terminology in the field of m etrology ’, which is publicly available at www.unmz.cz.  General Measure No 0111 -OOP -C076 -16 
3 1.6 
coeffic ient of variation  
the ratio V of the standard deviation s to the arithmetic mean x of a set of n measurements xi, given by 
the relationship:  


n
iix x
n x xsV
12) (
11 1
(1) 
1.7 
detection limit  LD 
the measured value of a quantity obtained by a measurement procedu re for which the probability of an 
inaccurate statement on the absence of a component in material is β, where the probability of an 
inaccurate statement on its presence is α. 
For a sample with a true content value of LD only 5  % of measurements will be erroneously declared 
as indistinguishable from the ambient environment (Type II error, β).The error β will equal error α 
(Type I error) in ambient measurement, when 5  % of ambient measurements exceed the measurement 
limit.Implicit values equal to 0.05 are recommended for α and β. 
The detection limit L D  is determined as follows:  
LD = 1.645
)(2Bu (2) 
where  B  ........   is the ambient value;  
t  ..........   is the ambient measurement time;  
u(B)  ....  is the ambient standard deviation.  
u(B) = 
tB (3) 
1.8 
coverage factor  
a numerical coefficient ( k) used as a multiplier of the combined standard uncertaint y in order to obtain 
an expanded uncertainty  
 
1.9 
decision variable  
a variable used to decide whether a given physical phenomenon is or is not present  
 
1.10 
decision level  
a fixed decision variable value that can be used to help decide if a given physical phenomenon is 
present if the result of the current measurement of the physical phenomenon has been exceeded  
 
1.11 
effective measuring range  
the range of values of the measured activity concentration within which the properties of the part of 
the apparatus or system comply with the requirements of the specifications  
 
1.12 
dynamic range  
the ratio of the signal at the maximum measurable value of a quantity and the signal at the decision 
level  General Measure No 0111 -OOP -C076 -16 
4 1.13 
indication error  
the difference between the indicated value of a quantity  and this quantity's conventionally true value 
c at the measurement point  
=  – c (4) 
1.14 
relative basic error  
the relative error of a specification ei of part of a device or a system with respect to the given quantity 
under specified refe rence radiation and under specified reference conditions, expressed as:  
 
cc
ie
(5) 
where:   ..........  the indicated value of the quantity:  
c  ........   the quantity's conventional value at the measurement point.  
1.15 
response time  
the time needed after a step  change in the measured quantity for the change in the output signal to first 
achieve a given relative value, usually 90 % of the final value  
1.16 
monitor air circuit efficiency  
the efficiency of the monitor's air circuit describes activity losses on the m onitor's walls between the 
circuit intake and the capture medium; it is defined as the ration of the total activity available for 
sampling by the monitor and the total activity in the air at the monitor's intake  
1.17 
reference response  
under standard test conditions is given by the following relationship:  
crefAAR
(6) 
where:  A ......  the value of the activity concentration indicated by the tested device or system;  
Ac .....  the conventional value of the activity concentration  
1.18 
sensitivity  
is the ratio of the value obtained through measurement and the conventional activity value  
AB-IS
(7) 
where:  I .......  the indicated value from measurement of a radioactive sample;  
B ......  the indicated value from measurement without a radioactive sample;  
A ......  the con ventional activity value of the measured sample.  
1.21 
activity concentration  
activity per unit volume of air or gas  General Measure No 0111 -OOP -C076 -16 
5 1.22 
units  
this legislation uses the SI system of units; where appropriate, the following auxiliary units are used:  
 for time: year (y), day (d), hour (h), minute (min);  
 for energy: electron -volt (eV);  
 for activity concentration: becquerel per cubic metre (Bq/m3) 
2   Metrological requirements  
2.1 Rated operating conditions  
The monitor must comply with metrological requirements over the operatin g temperature and relative 
humidity range specified by the manufacturer.  
2.1.1 Reference conditions and standard test conditions  
The reference conditions and standard test conditions are listed in Table 1.  
Table 1 – Reference conditions and standard test c onditions  
Influencing variables  Reference conditions  Standard test conditions  
Ambient temperature  20 °C  18 °C to 22  °C 
Relative humidity  65 % 50 % to 75 %  
Air pressure 1) 101.3 kPa  86 kPa to 106 kPa  
Power supply 2) nominal supply voltage VN VN ± 1 % 
AC supply voltage frequency 2) nominal frequency  nominal frequency ±0.5  % 
AC supply voltage waveform 2) sinusoidal  sinusoidal with a total harmonic 
distortion of less than 5  % 
Ambient gamma radiation  kerma rate in air 0.20 Gy/h  kerma rate in air <0.25 Gy/h 
Electrostatic field  negligible  negligible  
External electromagnetic field  negligible  less than the smallest value causing 
interference  
External magnetic field  negligible  less than twice the Earth's magnetic 
field value  
Sampling flow rate  set to nomi nal flow rate (stipulated 
by the manufacturer)  set to nominal flow rate ± 5  % 
Control elements  configured for routine operation  configured for routine operation  
Radionuclide contamination  negligible  negligible  
Radon daughters (222 and 220)  negligible  negligible  
Contamination by chemical 
products  negligible  negligible  
1) If the detection method is particularly sensitive to changes in air pressure, conditions are restricted to 
±5 % of reference pressure.  
2) DC power can be used, in which case no frequenc y is specified.  General Measure No 0111 -OOP -C076 -16 
6 2.2 Measuring range  
The measuring range of the noble gas monitor is stipulated by the manufacturer.  
2.3 Instrument accuracy  
The manufacturer must stipulate the ratio between a reading on the measuring instrument and the 
activity of a refer ence source when the instrument is operating under standard test conditions and is 
configured according to the manufacturer's instructions.The reference response uncertainty must be 
specified.The reference response must not differ by more that 15 % of the value specified by the 
manufacturer.  
2.4   System linearity  
Under standard test conditions, the relative error of a reading must be less that ±10  % over the entire 
effective measurement range.Uncertainty of sources of radiation is not included.When fixed s ources 
are used, then  and c apply to sensitivity during relative error calculations.  
2.5 Response of monitors without specification of radionuclides to other radioactive 
gases  
The manufacturer must specify the response of the apparatus to radioactive ga ses other than reference 
radioactive sources.The range of gases of interest is stipulated by the manufacturer, and a 
representative selection must be made from these for testing.It must be demonstrated that the 
characteristics of the apparatus comply with specifications.  
2.6 Response of monitors for specific radionuclides to other radioactive gases  
The manufacturer must specify the response of the apparatus to radioactive gases other than those to 
be measured; this response must be less than 15 % of the res ponse to a specific gas.The activity 
concentration of the gas must be sufficient to provide an indicated value that demonstrates that the 
apparatus meets requirements.  
2.7 Response to ambient gamma radiation  
The manufacturer must stipulate the decision lev el and the maximum reading when a detector with 
protection from ambient gamma radiation is irradiated in the position specified by the manufacturer 
with a step change in the kerma rate in air from the reference ambient air kerma rate to 10  Gy/h from 
137Cs.The response to irradiation with gamma radiation at any orientation and any gamma radiation 
energy up to 1.3 MeV (60Co) must not exceed double the decision level value.  
2.8 Overload  
Unless agreed upon otherwise between the manufacturer and user, the devic e must indicate a reading 
past the upper end of the scale or indicate overload if it is irradiated by a source with activity 
concentration 10 times that of the upper limit of the measurement range, and once the source of 
overload is eliminated, must operat e normally.  
2.9 Detection and evaluation apparatus start -up time  
When irradiated with a source of radiation, the apparatus must indicate a value that will not differ by 
more than ±10  % of the value obtained under standard conditions during the first 30 min utes after 
being switched on.  General Measure No 0111 -OOP -C076 -16 
7 2.10 Statistical fluctuations  
Given the statistical nature of radiation, read values may fluctuate around a central value.The activity 
value coefficient of variation caused by statistical fluctuations must be less than 10 % fo r readings past 
the first decade of the effective measurement range.  
2.11 Detection and evaluation apparatus reading stability  
The reading indicated for a given source of radiation after 30 minutes of operation must not change by 
more than 10 % over the su bsequent 100 hours.  
2.12 Influence of pressure changes in the measurement chamber  
Pressure changes in the measurement chamber influence response for a given activity concentration of 
measured air or gas.The manufacturer will stipulate the compensation algo rithm for these pressure 
changes.  
2.13 External leak  
This test is used to determine the size of an external leak, which characterises the leak -resistance of the 
measurement chamber.  
2.14 Ambient temperature  
The indicated value must remain within the limits  specified in Table 2 for the temperature range 
specified by the manufacturer.For this type of apparatus, detection and sampling apparatus may 
operate under different climactic conditions than the evaluation apparatus.Part or all of the detection 
apparatus  may operate at a higher temperature than specified in Table 2.In this case, the relevant test 
must be stipulated by the manufacturer.  
Table 2 - Ambient temperature  
Ambient temperature  Deviations under standard conditions  
+10 °C to +35  °C 
(midpoint:+22  °C) ±10 % 
−10 °C to +40  °C 
(midpoint:+15  °C) ±20 % 
−25 °C to +50  °C 
(midpoint:+12  °C) ±50 % 
2.15 Relative humidity  
Deviations caused by relative humidity up to 90 % at 35  °C must be less than 10 %.  
3   Technical requirements  
3.1 General requirements  
The main requi rement is the ability to measure a defined the emission level characterised by activity 
concentration and overall emission flow rate.  General Measure No 0111 -OOP -C076 -16 
8 3.2 Monitor types  
3.2.1    General  
The types of apparatus under consideration for monitoring gas emissions are radioactive aerosol 
monitors, noble gas monitors and monitors for identification of specific radionuclides.  
3.2.2  Classification of noble gas emission monitors  
An apparatus can be classified according to the type of radiation detected:  
 gamma;  
 beta;  
 specific radionucli des. 
An apparatus can also be classified according to measurement method:  
 direct measurement with the detector in the outlet flow or in its vicinity;  
 continuous sampling of part of the flow from a monitoring point to a remote location.  
3.3 Overall apparatu s design  
Various monitor configurations are possible depending on the exact circumstances and requirements 
for the given installation.Regardless of these variants, the apparatus must meet the following 
requirements:  
3.3.1  Direct -measurement apparatus  
If me asurement is performed directly in the emission flow or in its vicinity, only the detector and the 
bare minimum of electrical components must operate in these conditions.Unless there are special 
circumstances, this type of apparatus must not contain detect ors that are especially sensitive to 
changes in ambient conditions or that require frequent checking and adjustment.  
The relevant control and evaluation apparatus must be installed in a regulated environment if possible 
in order to minimize influences on i ts characteristics and to provide easy access for operation and 
maintenance.  
3.3.2  Indirect -measurement apparatus  
If representative emission samples are collected continuously to a remote location, the sampling and 
detection apparatus (except for the sampl ing nozzle and pipes) and the control and evaluation 
apparatus must be located in a regulated environment.If this is not practical (for example due to 
excessive sampling pipe length), the same restrictions as for the detection apparatus must be applied 
(in accordance with 3.3.1) to ensure quick response to any increase in activity level.  
3.4 Sampling and detection apparatus  
3.4.1  Sampling and intake pipes  
The following characteristics must be considered and agreed upon:  
 the influence of flow rate and pressu re on measurement;  
 transport delay to the detector (flow rate, pipe diameter, etc.).  
3.4.2  Intake part  
The sampling circuit intake must have a suitable intake part in order to eliminate all particles, and, if 
necessary, iodine.In order to preserve the spec ified characteristics of the apparatus, this part must not 
capture or temporarily hold back noble gases and reduce flow rate.  General Measure No 0111 -OOP -C076 -16 
9 The apparatus must also have suitable shielding to protect individuals and limit influence on the 
detection apparatus from radiati on from radionuclides accumulated on these parts during the sampling 
period.This part must be accessible and its activity must be monitored.  
It is necessary to note that iodine isotopes decay into noble gases.This is why if iodine filters are used 
at the i ntake of the monitor circuit, an analysis must be performed to demonstrate that iodine captured 
on the filter does not cause erroneous noble gas release estimates.  
3.4.3  Sampling chamber  
When a measuring chamber or gas chamber providing the given volume of  gas for measurement using 
a submerged or nearby detector is used as part of the sampling and detection apparatus, the following 
requirements have to be met:  
 The sampling chamber must be of flow -through type.It can contain an absorption medium or 
compressi on apparatus.  
 The volume of the sampling chamber and the operating pressure must be specified.  
 The detector must be separated from the measured gas or air by a protective window or 
partition.  
 It must be easy to remove the detector from the chamber for purp oses of repair or 
replacement.The detector must be attached in such a way that in all cases it can be returned to 
the appropriate geometric position and this position can be maintained.  
 If an absorption medium is used to increase gas monitor response for a  given radioactive gas 
activity concentration, the sorbent type and its characteristics must be specified for various 
measured gases.  
3.4.4  Radiation detector  
Any type of detector can be used that is suitable for the required measurement.The manufacturer m ust 
specify the detector type and all relevant characteristics, above all the response at operating geometry 
for activities of gases that are to be measured, and for activities of interfering radionuclides.  
Beta radiation detector  
The manufacturer must spe cify the dimensions of the detector and detection characteristics, for 
example effective area and thickness of all protective barriers etc.  
Gamma radiation detector  
These devices measure gamma radiation directly, and must generate an alarm if required.Ambi ent 
radiation must be taken into account for this monitor type.  
Detector of specific gamma radionuclides  
This detector combines gamma radiation measurement and spectroscopic radiation analysis.The 
manufacturer must specify the detector's resolution and eff iciency as a function of energy.  
3.5 Measurement and indication characteristics  
3.5.1  Effective measurement range  
The effective measurement range must be appropriate to the given application.  
3.5.2  Measurement characteristics  
The manufacturer must specify the decision level, detection limit and effective measurement range of 
the apparatus.These characteristics must be provided for specified radionuclides, taking into account 
the reference ambient gamma radiation level (0.2  Gy/h) and activity concentrations  in air (of radon 
and its daughters).  General Measure No 0111 -OOP -C076 -16 
10 3.5.3    Display  
The indicated value must correspond to the true value of emission activity concentration.This activity 
concentration is usually given in Bq/m3 for the reference radionuclide or selected radionuclides fr om a 
mixture if a monitor that can distinguish radionuclides is used.  
3.6 Reliability  
The start -up time of the entire apparatus must be less than 30 minutes.  
All apparatus must be designed to be as reliable as possible with minimum undetected faults.  
The m anufacturer must provide documentation concerning the expected MTBF of critical components 
such as air pumps, detectors, flow rate meters, pressure meters, etc.  
The manufacturer must specify the periodicity of regular maintenance and must fully describe al l 
maintenance procedures.Maintenance requirements should be minimised.  
Warnings concerning faults must be available, indicating the system has a fault such as a power supply 
outage or a component failure.  
3.7 Alarms  
3.7.1  Alarm types  
Alarms and indication elements must be appropriate to the purpose of the apparatus.  
High -level alarms and fault alarms must provide separate local visual indication on the monitor, and 
must also have two sets of output contacts (which may be common for all fault alarms) for ext ernal 
warning purposes.Audible alarms may also be provided.  
All alarm functions must have means of testing alarm functionality.In the case of a configurable alarm, 
it must be possible to perform a check within the configuration range with indication of the  current 
operating alarm point.  
Alarm circuits must operate in a mode where alarm conditions are maintained until they are 
specifically reset using a reset button, or in a mode where they automatically reset when the alarm 
state disappears.  
3.7.2  High -level alarms  
Configurable high -level alarms covering the entire effective measurement range must be provided.  
3.7.3  Fault alarms  
a) An alarm indicating loss of detector signal must be provided.  
b) An alarm indicating loss of sampling in the circuit must be provided.  
c) An alarm indicating faults in electronic system circuitry must be provided.  
d) Alarms must indicate the sources of defects and must have an automatic diagnostic system.  
e) There must be a separate indication for each fault.  
3.8 Means of indication  
Aside from vi sual indication of the measured value, the following must be indicated:  
 power is on;  
 the air fan (if present) is on;  
 the high -voltage power supply for the detector (if present) is on;  
 the flow or level in the detector coolant tank (if present).  General Measure No 0111 -OOP -C076 -16 
11 If air flow s through the apparatus, suitable flow measurement indication must be provided.  
Outputs allowing remote indication of measurement and alarms must be provided.  
3.9 Means for operating checks  
Means must be provided for the user to provide periodic checks to ensure satisfactory apparatus 
operation, including calibration and verification of measurement linearity.These means must be 
installed in a manner that allows checks to be performed from the control and evaluation unit.  
It must be possible to check apparat us calibration at two representative points within the measuring 
range.  
These checks must be performed using one or more (as needed) suitable sources of 
radiation.Measurement linearity can be checked electrically.  
3.10 Means for configuration and maintenan ce 
All electronic devices must have a sufficient number of easily accessible test points to facilitate 
configuration and defect localisation.All special maintenance tools and the appropriate maintenance 
manual must be provided.  
All apparatus must be design ed to facilitate easy repair and maintenance.  
The display must provide information on automatic diagnostic elements.  
3.11 Control and evaluation apparatus  
Control and evaluation apparatus comprises primarily the following parts:  
 electrical control and powe r supply;  
 electronic measuring apparatus;  
 measurement display;  
 warning signal and alarm units.  
The apparatus can be connected to a central radiation situation display panel.In this case it must be 
possible to install it in electronic frames of standardised  dimensions.  
3.12 Ambient shielding or compensation apparatus  
This apparatus or procedures are used to reduce the influence of the ambient environment on 
measurement.They involve the following types:  
 shielding apparatus;  
 electronic apparatus;  
 software meth ods. 
These types maybe incorporated into the overall system design as needed.  
Shielding must provide identical radiation attenuation in all directions from the detector's sensitive 
volume, taking into account the structural materials used in the detection apparatus and the detector's 
angular response.Shielding thickness must be stipulated taking into account the detector's detection 
efficiency.  
If it is not possible to easily remove the apparatus from the shielding, the shielding must be easy to 
disassemble , and thus must comprise overlapping building -block elements weighing 15 kg or less, 
unless specified otherwise by the manufacturer.  General Measure No 0111 -OOP -C076 -16 
12 If electronic methods employing auxiliary detectors are used to reduce the influence of the ambient 
gamma radiation, these detectors must be selected and situated to achieve the best possible 
compensation, taking into account the gamma energy range and radiation direction.  
3.13 Apparatus noise levels  
Apparatus noise is primarily due to the sampling and detection apparatus, and  specially from the 
operation of the pipe system and resultant vibrations.  
The manufacturer must select components and design the apparatus to minimise noise appropriately to 
the type of environment for which the apparatus is intended.  
3.14 Electromagnetic  interference  
Measuring instruments must not be influenced by ambient electrical and electromagnetic interference, 
and must comply with the requirements of relevant separate legislation2.. The change in the response 
of the measuring instrument must not exc eed 1 % during the interference test.All necessary measures 
to minimise electromagnetic interference must be implemented, both received and emitted by the 
apparatus.  
 Severity level 3 is used for resistance.  
 Severity level A is used for emission.  
3.15 Power  
The apparatus must be designed to operate on single -phase AC power in one of the following 
categories according to:  
 series I:230 V AC;  
 series II:100 V AC;  
 series III:120 V or 240 V AC;  
 series IV:24 V DC.  
The apparatus may be designed to operate on a low -voltage source of backup power in case of a power 
outage.In these cases it is desirable that the apparatus does not malfunction due to the power supply 
switch or that no alarm is triggered, but this switch must be indicated.  
Air fan motors may use three -phase power.  
3.16 Tamper protection  
The parts of the measuring instrument essential to its metrological characteristics must be designed to 
be secured in such a way as to provide proof of any unauthorised interference.  
If the response of the measuring instrum ent can be adjusted to correct for long -term changes in 
response, correct for the effect of temperature and pressure on response, or through application of a 
corrective factor, then the measuring instrument must be designed to rule out accidental changes t o 
any factors configured by its operator.  
Control switches and potentiometers must either be inside the measuring instrument and inaccessible 
from the outside without using tools, or be clearly marked and fitted with a scale so that they can be 
precisely a djusted according to the resolution of the measuring instrument and then locked in order for 
the settings not to be changed accidentally.Correction factors and calibration coefficients stored 
                                                      
2 Government Regulation No 117/2016 on product conformity assessment from the perspective of 
electromagnetic compatibility when being placed on the market  General Measure No 0111 -OOP -C076 -16 
13 digitally may not be changed unless the operator enters the secu rity code (or password) or changes the 
position of the blocked or inaccessible switch.  
3.17 Safety  
The measuring instrument must be safe in accordance with the basic principles of safety of ionising 
radiation installations and the requirements of relevant technical regulations under the conditions of 
normal use for the intended purposes.  
4   Measuring instrument markings  
4.1   Markings on the measuring instrument  
The following information must be provided on each part of the measuring instrument, which may 
consist of two functionally separate parts:  
a) manufacturer identification;  
b) measuring instrument type;  
c) the serial number of the the measuring instrument's detector(s) and evaluation unit, pumps, flow 
meter;  
d) type approval mark;  
e) ionising radiation meter safety information.  
All labels and inscriptions must be legible, durable, unambiguous and impossible to remove using 
common means.  
4.2 Official mark placement  
The placement of official marks on the detection part and the evaluation unit is specified in the type 
approval certificate.  
Where possible, marks are to be placed on the front panel of the display unit so that they do not cover 
any of the data on the measuring instrument.  
5   Type approval of measuring instruments  
5.1 In general  
The measuring instrument typ e approval process includes the following tests:  
a) external inspection;  
b) apparatus accuracy;  
c) system linearity;  
d) response to radioactive gases;  
e) response to ambient gamma radiation;  
f) overload;  
g) detection and evaluation apparatus start -up time;  
h) statistical fluctuat ions;  
i) detection and evaluation apparatus reading stability;  
j) influence of pressure changes in the measurement chamber;  
k) external leak;  
l) influence of ambient temperature;  
m) influence of relative humidity  General Measure No 0111 -OOP -C076 -16 
14 n) electromagnetic compatibility.  
5.2 External inspection  
The external inspection assesses  
a) the completeness of the prescribed technical documentation, including the operating 
instructions;  
b) the conformity of the metrological and technical characteristics specified by the manufacturer in 
the documentation with this re gulation's requirements specified in Chapters  2 and 3 and Article 
4.1(a), (b) and (c);  
c) the completeness and status of the functional units of the measuring instrument according to the 
prescribed technical documentation;  
d) the software version of the measurin g instrument with the version specified by the 
manufacturer.  
5.3 Functional tests  
5.3.1    Instrument accuracy  
The apparatus operates under standard test conditions and is configured according to the 
manufacturer's instructions without the presence of refer ence radiation.The ambient value is 
recorded.Depending on the monitor's purpose, the tests are performed in one of two ways:  
1. air or gas marked with a known activity concentration passes through the apparatus at a constant 
flow rate for a sufficient amount of time to achieve measurement equilibrium, and the 
equilibrium value is recorded;  
2. the detector is submerged into a sufficiently large volume of gas with known activity 
concentration that is equivalent to the volume in the detector's actual operating posit ion, and the 
reading under equilibrium conditions is recorded.  
Rref is then calculated.  
The measured value must not exceed the permitted change limits specified in Article 2.3.  
5.3.2    System linearity  
The test is performed using a set of sources with the same radionuclide and geometric 
characteristics.Standard preparation of test sources used in required tests must be such that the 
uncertainty in the absolute conventional activity value ( sa) of each source is better than 10 % ( k = 2) 
and the relative conv entional activity value ( sr) between sources of the given test set is better than 5 % 
(k = 2).Test sources must be linked to approved reference standards.  
Tests can be performed in two ways:  
 with gaseous or solid sources of radiation; or  
 through the appli cation of an electrical signal.  
Type approval tests are performed at one point on each scale for instruments with a linear scale, and 
on each decade of the effective measurement range for instruments with a digital or logarithmic 
display at approximately 2 5 % of the most sensitive range or decade, at 50 % of the maximum of 
central ranges or decades, and 75 % of the maximum value.At least three of these tests must be 
performed using a radioactive source, with two being at limit values.When electrical signals  are used, 
they must be used for all ranges or decades (in addition to radionuclide sources).  
The measured value must not exceed the permitted change limits specified in Article 2.4.  
5.3.3  Response of monitors for specific radionuclides to other radioactiv e gases  
The test is performed in the same way as described in 5.3.1.  General Measure No 0111 -OOP -C076 -16 
15 The results must comply with criteria pursuant to Article 2.5.  
5.3.4  Response to ambient gamma radiation  
Because there is usually a relationship between the response to ambient gamma radi ation and the 
decision level, and both parameters depend on the given operational use, the response to gamma 
radiation as well as the decision level must be specified by the manufacturer.The manufacturer must 
stipulate the decision level and the maximum re ading when a detector with protection from ambient 
gamma radiation is irradiated in the position specified by the manufacturer with a step change in the 
kerma rate in air from the reference ambient air kerma rate to 10  Gy/h from 137Cs.The response to 
irradiation with gamma radiation at any orientation and any gamma radiation energy up to 1.3 MeV 
(60Co) must not exceed double the decision level value.  
The apparatus must operate under standard test conditions without the presence of a radioactive 
source, and  the indicated ambient value is determined.The 137Cs source is then situated relative to the 
detector so that the distance between the source and detector is at least 2 metres, and the conventional 
kerma rate in air at the detector location, if the detecto r was not present, would be 
10 Gy/h  ± 10 %.The detector's reference orientation relative to the source must comply with the 
manufacturer's specifications.Once irradiation has started, values are recorded at one -minute intervals 
until the values shown by t he apparatus have reached a steady state.Once a steady state has been 
achieved, at least 10 readings are performed.The decision level is calculated based on the last 
readings.This decision level must comply with the manufacturer's specifications.The maximu m 
reading of the evaluation apparatus must not exceed the value specified by the manufacturer.The 
detector is then irradiated at several source -detector geometries specified by the manufacturer.If the 
evaluation apparatus can be programmed with a compensat ion factor for gamma radiation, this factor 
must not be changed during this test.Readings on the evaluation apparatus in all directions must not 
exceed double the value specified by the manufacturer for the reference direction.  
The above test is repeated f or the reference source -detector direction using alternative sources of 
gamma radiation as specified by the manufacturer, including a 60Co source.If the evaluation apparatus 
can be programmed with a compensation factor for gamma radiation, this factor must  not be changed 
during this test.Readings on the evaluation apparatus must not exceed double the value specified by 
the manufacturer for 137Cs. 
The measured value must not exceed the permitted change limits specified in Article 2.7.  
5.3.5  Overload test  
Unless otherwise specified by the manufacturer, the device must indicate a reading past the upper end 
of the scale or indicate overload if it is irradiated by a source with activity concentration 10 times that 
of the upper limit of the measurement range, and once the source of overload is eliminated, must 
operate normally.  
a) Detection apparatus is exposed to a source of radiation with activity that provides a reading at 
approximately 50 % of the first decade of the measurement range, and the reading is recorded.  
b) Detection apparatus is exposed to a source of radiation with activity 10 times the maximum 
measurable value.Irradiation is maintained for at least 10 minutes, and the instrument is checked 
to ensure that it permanently indicates a reading past the upper e nd of the scale.  
c) The source of radiation is removed and after a period of time specified by the manufacturer, 
usually less than one hour, the detection apparatus is irradiated under the same conditions as in 
a).The readings must not differ by more than 10 % of the original value.  
5.3.6  Detection and evaluation apparatus start -up time  
When irradiated with a source of radiation, the apparatus must indicate a value that will not differ by 
more than ±10  % of the value obtained under standard conditions during t he first 30 minutes after 
being switched on.  General Measure No 0111 -OOP -C076 -16 
16 Prior to this test, the apparatus must be disconnected from power for at least one hour.A source of 
radiation is used that provides a reading at approximately one -third to one -half of the range 
maximum.The detec tion and evaluation apparatus is switched on.Readings are recorded every five 
minutes for one hour.Ten hours after the apparatus was switched on, a sufficient number of readings is 
taken in accordance with Chapter 5.3.7, and the mean value is used as the ' final value' of the 
readings.A graph of the indicated activity value over time is drawn, and if needed a correction is made 
for half -life.The difference between the 'final value' and the value read from the graph for 30 minutes 
must lie between specified l imits.  
NOTE : If activity is very low, less than 10 times the decision level, it may occur during the start -up period that 
the apparatus will not provide the required indicated value.This is due to statistical deviations at low measured 
impulse frequencies.  
5.3.7  Statistical fluctuations  
Given the statistical nature of radiation, read values may fluctuate around a central value.The activity 
value coefficient of variation caused by statistical fluctuations must be less than 10 % for readings past 
the first decade of the  effective measurement range.  
A radioactive source that provides an indicated value between 10 and 20 times the decision level is 
used.At least 10 readings are taken at appropriate intervals to obtain independent values.The mean 
value and coefficient of va riation are calculated from all readings.The coefficient of variation must be 
within the required limits.  
The measured value must not exceed the permitted change limits specified in Article 2.10.  
5.3.8  Detection and evaluation apparatus reading stability  
The reading indicated for a given source of radiation after 30 minutes of operation must not change by 
more than 10 % over the subsequent 100 hours.  
A radioactive source that provides an indicated value between 10 and 20 times the decision level is 
used.A s ufficient number of readings are performed after 30 minutes, then additional readings after 10 
hours and 100 hours without any changes to apparatus settings or conditions.The mean reading values 
for all times must be between the specified limits.  
If needed , readings must be corrected for half -life. 
The measured value must not exceed the permitted change limits specified in Article 2.11.  
5.3.9  Influence of pressure changes in the measurement chamber  
The purpose of this test is to test the method used to comp ensate for pressure changes in the 
measurement chamber.Changes causing a pressure drop or increase in the measurement chamber can 
lead to an incorrect measured value for gas or air activity concentration under standard 
conditions.Pressure change values mus t be stipulated by the manufacturer.  
For this test, the monitor must be equipped with a pressure meter in the measurement chamber.A 
calibrated pressure sensor (differential manometer, etc.) is inserted into the closed circuit with the 
measurement chamber a t a point specified by the manufacturer so that the pressure change in the 
measurement chamber is measured.Nominal activity concentration at nominal pressure in the 
measurement chamber is measured.The pressure in the measurement chamber is then changed whi le 
the activity of the reference radionuclide is kept constant, until a pressure change of +10% above 
nominal pressure is achieved under standard test conditions, unless specified otherwise by the 
manufacturer.The conventionally true value of the activity concentration is measured under these 
conditions.  
The measured value must not exceed the permitted change limits specified in Article 2.12.  
5.3.10  External leak  
This test is used to determine the size of an external leak.  General Measure No 0111 -OOP -C076 -16 
17 The size of the leak is measured u sing two volume meters or flow rate meters; they must be mutually 
calibrated to an accuracy greater than 1 %.One meter is situated before the measurement chamber and 
the second in the direction of flow past the measurement chamber.A series of ten consecuti ve 
measurements performed at suitable time intervals.The mean values of flow rates measured in before 
and after must not differ by more than 5 % during a standard sampling period.If needed, corrections 
for air pressure differences are performed.  
5.3.11  Amb ient temperature  
For this type of apparatus, detection and sampling apparatus may operate under different climactic 
conditions than the evaluation apparatus.Part or all of the detection apparatus may operate at a higher 
temperature.  
The detection apparatus  is irradiated using a suitable test source in a manner that provides a known 
nominal reading value under standard test conditions.This test is usually performed in a climate 
chamber.It is usually not necessary to regulate humidity in the chamber if the ap paratus is not 
especially sensitive to humidity changes.Temperature is maintained at both limit values of the agreed -
upon temperature range for at least 24 hours.During the last 30 minutes of this interval, the indicated 
value is read, which must be within  appropriate limits.The indicated value is also read at the midpoint 
of the temperature range shown in Table 2.If the reading at this median temperature is not within 
±10 % of the monitor's reading at the reference temperature, the manufacturer must specif y the 
difference at this point.  
The measured value must not exceed the permitted change limits specified in Article 2.14.  
5.3.12  Relative humidity  
For this type of apparatus, detection and sampling apparatus may operate under different climactic 
conditions  than the evaluation apparatus.Part or all of the detection apparatus may operate at a higher 
relative humidity.  
The detection apparatus is irradiated using a suitable test source in a manner that provides a known 
nominal reading value under standard test conditions.The test may be performed at one temperature, 
35 °C, and relative humidity of 90 %; the permitted reading deviation of ±10  % of the value is in 
addition to the permitted deviation caused by temperature alone.  
The measured value must not exceed t he permitted change limits specified in Article 2.15.  
5.4 Electromagnetic compatibility tests  
EMC tests are performed using an aerosol monitor connected according to the manufacturer's 
specifications.These tests must demonstrate that the aerosol monitor co mplies with the requirements of 
relevant separate legislation2). 
5.5.1  Immunity to electrostatic discharge  
Immunity to electromagnetic discharge is tested with the apparatus switched on, using a contact 
discharge of 6 kV and an air discharge of 8 kV.Discha rges are applied to conductive surfaces and 
connecting plates.  
After this test, a subsequent apparatus accuracy test must not result in a measured deviation that 
exceeds limits specified in Article 2.3.  
5.4.2  Immunity to high -frequency electromagnetic fiel ds 
Immunity to a radiated high -frequency field is tested with the apparatus switched on, over a frequency 
range of 80 MHz to 3000 MHz, with field intensity of 10 V/m.Amplitude modulation 80  % AM/1  kHz 
sine. General Measure No 0111 -OOP -C076 -16 
18 After this test, a subsequent apparatus accuracy test must not result in a measured deviation that 
exceeds limits specified in Article 2.3.  
5.4.3  Immunity to transients  
Immunity to repeated electrical transients disturbances is tested with the apparatus switched on.A test 
voltage of ±0.5 kV, ±1 kV and ±2  kV is applied via a coupling circuit to power, earth and signal 
inputs/outputs.  
After this test, a subsequent apparatus accuracy test must not result in a measured deviation that 
exceeds limits specified in Article 2.3.  
5.4.4 Immunity to surges  
Immunity t o surges is tested by applying a test voltage of ±0.5 kV, ±1 kV and ±2  kV between power 
conductors.  
After this test, a subsequent apparatus accuracy test must not result in a measured deviation that 
exceeds limits specified in Article 2.3.  
5.4.5 Immunity t o conducted disturbances induced by radio frequency fields  
Immunity to conducted disturbances induced by radio -frequency fields are tested with the apparatus 
switched on over a frequency range of 150  kHz to 80  MHz.Amplitude modulation 10  % AM/1  kHz, 
voltag e 10 V.  
After this test, a subsequent apparatus accuracy test must not result in a measured deviation that 
exceeds limits specified in Article 2.3.  
5.4.6  Immunity to interference due to a damped wave  
Immunity to interference due to a damped wave is tested with the apparatus switched on, by applying 
damped waves to the monitor's power, signal and control inputs/outputs.The test level is defined as the 
voltage of the first peak (maximum or minimum) of the test waveform, and is non -symmetrical 2 kV, 
symmetrica l 1 kV for a slow 100 kHz and 1 MHz wave, and for a fast 3  MHz, 10  MHz or 30  MHz 
damped wave is 2 kV non -symmetrical.  
After this test, a subsequent apparatus accuracy test must not result in a measured deviation that 
exceeds limits specified in Article 2.3 . 
5.4.7  Immunity to supply voltage dips, short interruptions and voltage variations  
Immunity to supply voltage dips, short interruptions and voltage variations is tested with the apparatus 
switched on, by applying a voltage dip to 0 % Vt for 10  ms. 
After t his test, a subsequent apparatus accuracy test must not result in a measured deviation that 
exceeds limits specified in Article 2.3.  
5.4.8  Measurement of power line disturbances  
The tested monitor must comply with disturbance limits specified in Tables 3 a nd 4.The test is 
performed with the apparatus switched on by measuring power line disturbances on the monitor's 
power, signal and control inputs/outputs.If the reading on the measuring receiver fluctuates near limits, 
the reading must be monitored for at l east 15 seconds at each measurement frequency.The maximum 
value is recorded, except for random, brief extreme values, which are ignored.  
Table 3 contains voltage disturbance limits for power terminals.  General Measure No 0111 -OOP -C076 -16 
19 Table 3 - Limits for power line disturbances on power terminals  
Frequency range (MHz)  dB limits (µV)  
Quasi -maximum  Medium  
0.15 to 0.50  79 66 
0.50 to 30  73 60 
NOTE:    Lower limits apply to band edge frequencies.  
Table 4 contains voltage disturbance limits for signal inputs/outputs.  
Table 4 - Limits for pow er line disturbances on signal inputs/outputs  
Frequency range (MHz)  Voltage limits dB  (µV)  Current limits dB  (µA)  
Quasi -maximum  Medium  Quasi -maximum  Medium  
0.15 to 0.50  97 to 87  84 to 74  53 to 43  40 to 30  
0.50 to 30  87 74 43 30 
NOTE:    Lower limits app ly to band edge frequencies.  
5.4.9  Measurement of EM interference (radiated high -frequency interference)  
The tested monitor must comply with interference limits specified in Table 5.The test is performed 
with the apparatus switched on by measuring EM radi ation at 10 metres. If the reading on the 
measuring receiver fluctuates near the limits, the reading must be monitored for at least 15 seconds at 
each measurement frequency.The maximum value is recorded, except for random, brief extreme 
values, which are i gnored.  
Table 5 - Radiated EM interference limits when measured at 10 m  
Frequency range MHz  Quasi -peak limits dB (µV/m)  
30 to 230  40 
230 to 1000  47 
NOTE:    Lower limits apply to band edge frequencies.  
6   Initial verification  
6.1   General  
During initial  verification, the following tests are performed:  
a) visual inspection;  
b) apparatus accuracy;  
c) system linearity;  
d) response to ambient gamma radiation;  
e) overload;  
f) statistical fluctuations;  
g) detection and evaluation apparatus reading stability;  
h) external leak.  General Measure No 0111 -OOP -C076 -16 
20 6.2 Vis ual inspection  
The inspection is performed in accordance with Article 5.2.  
6.3 Functional tests  
6.3.1  Apparatus accuracy test  
The test is performed in accordance with Article 5.3.1.  
6.3.2  System linearity test  
The test is performed in accordance with Artic le 5.3.2.  
6.3.3  Test of response to ambient gamma radiation  
The test is performed in accordance with Article 5.3.4.  
6.3.4  Overload test  
The test is performed in accordance with Article 5.3.5.  
6.3.5  Statistical fluctuation test  
The test is performed in acco rdance with Article 5.3.7.  
6.3.6  Test of long -term stability of detection and evaluation apparatus readings  
The test is performed in accordance with Article 5.3.8.  
6.3.7  External leak test  
The test is performed in accordance with Article 5.3.10.  
7   Subseq uent verification  
7.1   General  
During subsequent verification, the following tests are performed:  
a) a visual inspection;  
b) apparatus accuracy;  
c) system linearity;  
d) overload;  
e) detection and evaluation apparatus reading stability;  
f) external leak.  
7.2 Visual inspecti on 
The inspection is performed in accordance with Article 5.2.  
7.3   Functional tests  
7.3.1  Apparatus accuracy test  
The test is performed in accordance with Article 5.3.1.  
7.3.2  System linearity test  
The test is performed in accordance with Article 5.3.2.  General Measure No 0111 -OOP -C076 -16 
21 7.3.3  Overload test  
The test is performed in accordance with Article 5.3.5.  
7.3.4  Test of long -term stability of detection and evaluation apparatus readings  
The test is performed in accordance with Article 5.3.8.  
7.3.5  External leak influence test  
The test  is performed in accordance with Article 5.3.10.  
8 Measuring instrument check  
When examining measuring instruments pursuant to § 11a of the Metrology Act at the request of a 
person who may be affected by an incorrect measurement, please proceed according t o Chapter 7.The 
maximum permissible error used is 1.25 times the maximum permissible errors pursuant to Chapter 7.  
9   Notified standards  
For the purposes of specifying the metrological and technical requirements for measuring instruments 
and specifying th e testing methods for their type approval and verification arising from this general 
measure, the CMI shall notify Czech technical standards, other technical standards or technical 
documents of international or foreign organisations, or other technical doc uments containing more 
detailed technical requirements (hereinafter referred to as ‘notified standards ’).The CMI will publish a 
list of these notified standards attached to the relevant measures, together with the general measure, in 
a manner accessible to  the public (on www.cmi.cz ). 
Compliance with notified standards or parts thereof is considered, to the extent and under the 
conditions stipulated by a general measure, to be compliance with the requirements stipulated by t his 
measure to which these standards or parts thereof apply.  
Compliance with notified standards is one way of demonstrating compliance with the 
requirements.These requirements may also be met by using another technical solution guaranteeing an 
equivalent o r higher level of protection of legitimate interests.  
II. 
G R O U N D S 
In accordance with §  14(1)(j) of the Metrology Act implementing § 6(2), §  9(1) and (9), and §  11a(3) 
of the Metrology Act, this general measure, stipulating metrological and technical requirements for the 
specified measuring instruments and test methods for the type approval and verification of the 
specified measuring instruments – 'Measuring instruments used to monitor activity limits and 
concentration of emissions from nuclear facilit ies, nuclear raw material mining or processing facilities, 
radioactive waste processing plants and from the processing or application of radioactive materials, 
and also used to determine environmental radiation exposure due to emissions – measuring 
instrum ents for continuous monitoring of radioactive noble gases in gas emissions from nuclear 
facilities'.  
Decree No 345/2002 specifying measuring instruments for mandatory verification and measuring 
instruments subject to type approval, as amended, classifies t he measuring instruments under item  8.1 
in the annex entitled ‘List of specified measuring instruments ’ as measuring instruments subject to 
type approval and mandatory verification.  
This legislation (General Measure) was notified in accordance with Directi ve (EU) 2015/1535 of the 
European Parliament and of the Council of 9 September 2015 laying down a procedure for the General Measure No 0111 -OOP -C076 -16 
22 provision of information in the field of technical regulations and of rules on Information Society 
services.  
III. 
I N S T R U C T I O N S 
In accordance with §  172(l) APC, in conjunction with §  39(l) APC, the CMI has stipulated a time limit 
for comments of 30  days as of the date of posting the draft on the official notice board.Comments 
submitted after this time limit will not be considered.  
The persons concerned are hereby invited to comment on this general draft measure.With regard to the 
provisions of § 172(4) APC, comments are to be submitted in writing.  
Pursuant to the provisions of § 174(1) APC, in conjunction with the provisions of § 37 (1) APC, it must 
be clearly stated who is submitting the comments, which general measure the comments concern, how 
the draft contradicts legislation or how the general measure is inaccurate. The comments must also 
contain the signature of the person making  the comments.  
The supporting documents for this draft general measure may be consulted at the Czech Metrology 
Institute, Legal Metrology Department, Okružní 31, 638 00 Brno, after making arrangements by 
telephone.  
This draft general measure shall be poste d for 15  days.  
 
 
 
 
 
 ................................ .......................   
RNDr.Pavel Klenovský  
Director -General  
 
 
Person responsible for accuracy:  Mgr.Tomáš Hendrych  
 
Posted on:  17.10.2018  
Signature of the authorised person confirming posting:     ................................ .............   
 
Removed on:  
Signature of the authorised person confirming r emoval:    ................................ ............