Nederlandse norm. NEN 5699 (en) Radioactivity measurements Determination method of the rate of the radon exhalation of dense building materials

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1 Dit document mag slechts op een stand-alone PC worden geinstalleerd. Gebruik op een netwerk is alleen. toestaan als een aanvullende licentieovereenkomst voor netwerkgebruik met NEN is afgesloten. This document may only be used on a stand-alone PC. Use in a network is only permitted when a supplementary license agreement for us in a network with NEN has been concluded. Nederlandse norm NEN 5699 (en) Radioactivity measurements Determination method of the rate of the radon exhalation of dense building materials Radioactiviteitsmetingen Methode voor de bepaling van de radonexhalatiesnelheid van steenachtige bouwproducten Vervangt NEN 5699:1999 Ontw. ICS augustus 2001

2 Normcommissie "Radioactiviteitsmetingen" Apart from exceptions provided by the law, nothing from this publication may be duplicated and/or published by means of photocopy, microfilm, storage in computer files or otherwise, which also applies to full or partial processing, without the written consent of the Netherlands Standardization Institute. The Netherlands Standardization Institute shall, with the exclusion of any other beneficiary, collect payments owed by third parties for duplication and/or act in and out of law, where this authority is not transferred or falls by right to the Reproduction Rights Foundation. Auteursrecht voorbehouden. Behoudens uitzondering door de wet gesteld mag zonder schriftelijke toestemming van het Nederlands Normalisatie-instituut niets uit deze uitgave worden verveelvoudigd en/of openbaar gemaakt door middel van fotokopie, microfilm, opslag in computerbestanden of anderszins, hetgeen ook van toepassing is op gehele of gedeeltelijke bewerking. Het Nederlands Normalisatie-instituut is met uitsluiting van ieder ander gerechtigd de door derden verschuldigde vergoedingen voor verveelvoudiging te innen en/of daartoe in en buiten rechte op te treden, voor zover deze bevoegdheid niet is overgedragen c.q. rechtens toekomt aan de Stichting Reprorecht. Although the utmost care has been taken with this publication, errors and omissions cannot be entirely excluded. The Netherlands Standardization Institute and/or the members of the committees therefore accept no liability, not even for direct or indirect damage, occurring due to or in relation with the application of publications issued by the Netherlands Standardization Institute. Hoewel bij deze uitgave de uiterste zorg is nagestreefd, kunnen fouten en onvolledigheden niet geheel worden uitgesloten. Het Nederlands Normalisatie-instituut en/of de leden van de commissies aanvaarden derhalve geen enkele aansprakelijkheid, ook niet voor directe of indirecte schade, ontstaan door of verband houdend met toepassing van door het Nederlands Normalisatie-instituut gepubliceerde uitgaven Nederlands Normalisatie-instituut Postbus 5059, 2600 GB Delft Telefoon (015) , Fax (015)

3 Contents Foreword Scope Normative references Terms and definitions Symbols and abbreviations Method of determination Administrative provisions; report...16 Annex A (informative) Method for the determination of the free radon exhalation rate of stony building materials: activity determination with semiconductor gamma-ray spectrometry...17 Annex B (informative) Method for the determination of the free radon exhalation rate of stony building materials; activity determination using nuclide-specific gamma-ray spectrometry

4 Foreword This standard is presented in the framework of the "Normstar II" project and will be part of the Dutch Building Decree through reference from the radiation performance standard. The aim of the "Normstar II" project is standardization of measurement methods for radiation and radioactivity. The project is mainly focussed towards subjects that are related to determining natural radionuclides and radioactivity measurements with regard to built environments. These standardized measurement methods are greatly required, on the one hand, because of the verification of determined or still to be determined limit values and, on the other hand, to obtain reliable and comparable measurement results. This need has been enhanced since the former State Secretary of the Netherlands Ministry of Housing, Spatial Planning and the Environment (VROM) made it known that a radiation performance standard would be part of the Dutch Building Decree within the framework of sustainable building. This standard is based on existing national and international regulations and standards and has come about after expert contribution and evaluation. The standard has two informative annexes. Each of these annexes describes a determination method that differs from the standard text for the determination of the free radon exhalation rate. Applying these annexes to determine the free radon exhalation rate leads to a result that is equivalent to the free radon exhalation rate determined in accordance with the method set down in the standard text. This means that the conclusion is justified that the methods given in Annexes A and B may also be used, in deviation of the standard text, to determine the free radon exhalation rate. 2

5 Radioactivity measurements Determination method of the rate of the radon exhalation of dense building materials 1 Scope This standard specifies a method for the determination of the free radon exhalation rate of a batch of stony building materials. The standard only refers to 222 Rn exhalation. NOTE Any contribution made by thoron ( 220 Rn) in relation to the measurement result can be ignored when the described method is performed. 2 Normative references The following standards contain provisions, which, through reference in this text, constitute provisions of the present standard. All standards are subject to revision; parties to agreements based on the present standard are encouraged to investigate the possibility of applying the most recent editions of the standards listed below. At the time of publication of the present standard, the editions and titles indicated were valid. Later review of these standards may result in change of titles. NEN 5955:1988 NEN 5965:1999 Concrete and mortar Sampling of fresh concrete and mortar Concrete Test specimens made of fresh concrete Making and curing 3 Terms and definitions For the purpose of this standard the following terms and definitions apply. 3.1 sample stony product drawn from a batch or an amount of fresh concrete taken from a batch 3.2 batch amount of stony building materials that is regarded as a unit and for which it is assumed that it has uniform characteristics or an amount of fresh concrete produced under uniform conditions and which has the same strength and environmental class or which has the same composition 3.3 test sample sample that is either the original sample or has been prepared from this and which is subjected to the test 3.4 radon radionuclide 222 Rn 3.5 radon exhalation rate radon activity that diffuses per unit of time from a stony building material to the air surrounding the material, in Bq/s NOTE By dividing the radon exhalation rate by either the area of the exhaling surfaces or by the mass of the sample, the areic radon exhalation rates and massic radon exhalation rates respectively can be calculated. 3

6 3.6 radon standard solution of 226 Ra or source of radon emanation with a defined activity or radon emanation rate respectively, which can be traced to the primary standard 3.7 stony building material product of stone or product that is made of one or more stony building materials and possibly admixtures and which has characteristics that meet previously set requirements after a formation process which may have been supplemented with a curing process if required NOTE The curing process, in which a chemical reaction occurs, may take place under ambient conditions (cold binding products), under elevated temperature (baked products) or under elevated temperature and pressures (autoclaved products). 3.8 ventilation rate rate at which the free volume is refreshed (in s -1 ) NOTE The ventilation rate can be calculated by dividing the volume flow rate (in m 3 /s) by the free volume (in m 3 ). 3.9 free radon exhalation rate radon exhalation rate under conditions that the radon activity at the surfaces of the stony building material equals zero NOTE The free radon exhalation rate is approximated by the radon exhalation rate if the radon activity at the surfaces of the building material has a sufficiently low value. This condition is met due to the requirement for the volume flow rate as prescribed in free volume volume of the exhalation vessel reduced by the volume of the physical size of the stony building material test sample 4 Symbols and abbreviations The present standard uses the symbols and names of quantities as mentioned below; the units in which the quantities shall be expressed are given as well. Symbol Name of quantity Unit A Ra the 226 Ra activity of the radon standard Bq E the free radon exhalation rate Bq/s E kar the characteristic free radon exhalation rate Bq/s K the confidence coefficient for which a value of 3 shall be used k N statistical coefficient R n the gross counting rate of test sample n as the result of radon and/or radon s -1 progenies on the adsorber R 0 the counting rate of the blank s -1 R min the minimum detectable counting rate as the result of radon and/or radon progenies s -1 on the adsorber s(e) the standard deviation of E Bq/s t 0 the counting time of the blank s t a the time that has elapsed between the start and the end of the adsorption period s 4

7 Symbol Name of quantity Unit t n the counting time of counting sample n s t w the time that has elapsed between the end of the adsorption period and the start of the count V the free volume to which the radon exhales m 3 V p the volume of the test sample m 3 V 1 the total uncertainty of the free radon exhalation rate Bq/s V 2 the dispersion of the results of the test samples Bq/s v(e) the coefficient of variation of the free radon exhalation rate v(ε) the coefficient of variation of the calibration factor v(r) the uncertainty due to counting statistics v(s) the uncertainty of the activity of the radon standard ε the calibration factor (Bq s) -1 λ Rn the decay constant of radon-222 (λ Rn = 2, s -1 ) s -1 λ v the ventilation rate s -1 µ ε the average calibration factor (Bq s) -1 µ E the average free radon exhalation rate Bq/s s 5 Method of determination 5.1 Principle The sample of the stony building material is conditioned at (20 ± 2) C and (50 ± 5) % relative humidity. After conditioning of the sample, the sample is placed in an exhalation vessel so that radon exhalation takes place towards the free volume of the exhalation vessel. The free radon exhalation rate is determined by flushing the radon activity using nitrogen from the free volume during a defined period and by collecting it on an adsorber (purge and trap method). The ventilation rate is chosen sufficiently larger than the radon decay rate to ensure that the radon exhalation rate approximates the free radon exhalation rate. The humidity of the gas, the volume flow rate and the temperature are kept at constant values whilst flushing. After the free volume has been flushed at least five times, the volumic radon activity of the free volume and of the outgoing nitrogen volume flow will be constant. Next, the nitrogen volume flow is passed over an adsorber used to collect the radon. The activity of the adsorbed radon and/or radon progenies will be determined using an integral measurement with a liquid scintillation counter after a defined collection period. The free radon exhalation rate is calculated starting from this. The test method consists of consecutively: drawing samples in accordance with 5.3; preparing test samples in accordance with 5.4; performing the test in accordance with 5.5; and processing results in accordance with 5.6. The method may only be used if the conditions listed in 5.2 have been met. NOTE Determination methods that deviate from this method are described in Annexes A and B. The methods lead to a free radon exhalation rate which is equivalent to the free radon exhalation rate determined in accordance with the standard text. Each of the methods described in Annex A or B may, therefore, be applied instead of the normative text. 5

8 5.2 Conditions No conditions are applicable. 5.3 Sampling Randomly take at least three representative samples of a batch of stony building materials except when a stony material made of cement concrete is involved. If the batch consists of products made of cement concrete, take at least three representative samples of the fresh concrete paste during pouring of the building product in accordance with clauses 3 and 4 of NEN Prepare a test cube from each of the fresh cement concrete samples, which measures 150 mm 150 mm 150 mm with a tolerance of no more than 0,5 %, and allow it to cure for 28 days in accordance with 3.6 of NEN NOTE 1 The tolerance related to the dimensioning of the cube deviates from the tolerance given in NEN In the case of concrete products, at least three samples may be drawn at random from a batch of concrete products. NOTE 2 The smaller the numbers of samples, the greater the statistical uncertainty will be in the result of the measurement; see Test samples Apparatus and devices a) Conditioning room Room in which the temperature can be set to a value of (20 ± 2) C and the relative humidity can be set to a value of (50 ± 5) %. b) Calibrated length measuring instrument reading uncertainty: at most 1 mm. c) Calibrated weighing apparatus measuring range: at least 1,5 times the mass of the test sample; reading uncertainty: at most 0,01 %. d) Relative-humidity meter measuring range: 40 % to 60 %; measurement uncertainty: at most 3 %; reading uncertainty: at most 1 %. e) Temperature gauge measuring range: 15 C to 25 C; measurement uncertainty: at most 1 C; reading uncertainty: at most 0,5 C. 6

9 f) Saw Number and dimensions Take or prepare one test sample from each sample. A test sample can be sawed from a sample that is too large for the exhalation vessel (blocks, panels, units). Ensure, however, that the volume of the exhalation vessel is at least twice as large as the volume of the test sample or of the combined volume of test samples that are to be tested simultaneously. Determine, for each test sample, the mass with an accuracy of three decimal places in kg, the dimension with an accuracy of three decimal places in m, and, if required, the external surface with an accuracy of three decimal places in square metres if that surface cannot easily be derived from the dimensions. NOTE The total volume of the test samples is not prescribed in this standard. It should be obvious that as the volume becomes greater, the material will show a higher rate of exhalation and, when the adsorption time remains unchanged, the uncertainty of the rate of exhalation will decrease. In general, test samples with a volume in the range of 3 dm 3 to 10 dm 3 will be aimed at Conditioning Cement concrete Store the test samples prepared from cement concrete in the conditioning room after the curing period of 28 days has elapsed. Set the temperature and the relative humidity of the conditioning room at (20 ± 2) C and (50 ± 5) %. Wait until the moisture content is in equilibrium with the set conditions. This is the case if the mass of the sample over a period of seven days deviates by less than 0,07 % from the value determined during the previous measurement. Once this is the case, testing can start. Conditioning, however, does not have to last longer than eight weeks. If the moisture content is not in equilibrium by this time, testing shall start between eight and twelve weeks after the curing period of 28 days. NOTE The age of the test sample will influence the radon exhalation. As a result of the aging processes, the free radon exhalation rate of building materials can change during the utilization period. It is, for example, known that the free radon exhalation rate of certain types of cement concrete may decrease over a period of 6 years by approximately 50 % when stored at a relative humidity of approximately 50 % Other stony materials Store the test samples, after preparation, in the conditioning room. Set the temperature and the relative humidity of the conditioning room at (20 ± 2) C and (50 ± 5) %. Wait until the moisture content is in equilibrium with the set conditions. This is the case if the mass of the sample over a period of seven days deviates by less than 0,07 % from the previous measurement. Once this is the case, testing can start. If the moisture content is not in equilibrium, the test shall start twelve weeks after conditioning has begun. 5.5 Test Principle The test shall be performed using a method as described in using apparatus and devices as determined in and under conditions as described in The results of the test shall be processed as set down in Conditions None. 7

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