1、 ISO 2012 Measurement of radioactivity in the environment Air: radon-222 Part 6: Spot measurement method of the activity concentration Mesurage de la radioactivit dans lenvironnement Air: radon 222 Partie 6: Mthode de mesure ponctuelle de lactivit volumique INTERNATIONAL STANDARD ISO 11665-6 First e
2、dition 2012-07-15 Reference number ISO 11665-6:2012(E) ISO 11665-6:2012(E) ii ISO 2012 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2012 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mecha
3、nical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso
4、.org Published in Switzerland ISO 11665-6:2012(E) ISO 2012 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope 1 2 Normative references . 1 3 T erms, definitions and symbols 1 3.1 T erms and definitions . 1 3.2 Symbols . 2 4 Principle . 2 5 Equipment . 2 6 Sampling 3 6.1 Samplin
5、g objective . 3 6.2 Sampling characteristics . 3 6.3 Sampling conditions . 3 7 Detection 3 8 Measurement 4 8.1 Procedure 4 8.2 Influence quantities 4 8.3 Calibration . 4 9 Expression of results . 4 9.1 Radon activity concentration . 4 9.2 Standard uncertainty 5 9.3 Decision threshold and detection l
6、imit . 5 9.4 Limits of the confidence interval . 5 10 Test report . 5 Annex A (informative) Measurement method using scintillation cells . 7 Bibliography .13 ISO 11665-6:2012(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (
7、ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, go
8、vernmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IE
9、C Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the memb
10、er bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 11665-6 was prepared by Technical Committee ISO/TC 85, Nuclear energy,
11、nuclear technologies, and radiological protection, Subcommittee SC 2, Radiological protection. ISO 11665 consists of the following parts, under the general title Measurement of radioactivity in the environment Air: radon-222: Part 1: Origins of radon and its short-lived decay products and associated
12、 measurement methods Part 2: Integrated measurement method for determining average potential alpha energy concentration of its short-lived decay products Part 3: Spot measurement method of the potential alpha energy concentration of its short-lived decay products Part 4: Integrated measurement metho
13、d for determining average activity concentration using passive sampling and delayed analysis Part 5: Continuous measurement method of the activity concentration Part 6: Spot measurement method of the activity concentration Part 7: Accumulation method for estimating surface exhalation rate Part 8: Me
14、thodologies for initial and additional investigations in buildings The following parts are under preparation: Part 9: Method for determining exhalation rate of dense building materials P a r t 1 0 : Determination of diffusion coefficient in waterproof materials using activity concentration measureme
15、nt iv ISO 2012 All rights reserved ISO 11665-6:2012(E) Introduction Radon isotopes 222, 220 and 219 are radioactive gases produced by the disintegration of radium isotopes 226, 224 and 223, which are decay products of uranium-238, thorium-232 and uranium-235 respectively, and are all found in the ea
16、rths crust. Solid elements, also radioactive, followed by stable lead are produced by radon disintegration 1 . When disintegrating, radon emits alpha particles and generates solid decay products, which are also radioactive (polonium, bismuth, lead, etc.). The potential effects on human health of rad
17、on lie in its solid decay products rather than the gas itself. Whether or not they are attached to atmospheric aerosols, radon decay products can be inhaled and deposited in the bronchopulmonary tree to varying depths according to their size. Radon is today considered to be the main source of human
18、exposure to natural radiation. The UNSCEAR (2006) report 2suggests that, at the worldwide level, radon accounts for around 52 % of global average exposure to natural radiation. The radiological impact of isotope 222 (48 %) is far more significant than isotope 220 (4 %), while isotope 219 is consider
19、ed negligible. For this reason, references to radon in this part of ISO 11665 refer only to radon-222. Radon activity concentration can vary by one to multiple orders of magnitude over time and space. Exposure to radon and its decay products varies tremendously from one area to another, as it depend
20、s firstly on the amount of radon emitted by the soil and the building materials in each area and, secondly, on the degree of containment and weather conditions in the areas where individuals are exposed. The values commonly found in the continental environment are usually between a few becquerels pe
21、r cubic metre and several thousand becquerels per cubic metre. Activity concentrations of one becquerel per cubic metre or less can be observed in the oceanic environment. Radon activity concentrations inside houses may vary from several tens of becquerels per cubic metre to several hundreds of becq
22、uerels per cubic metre 3 . Activity concentrations can reach several thousands of becquerels per cubic metre in very confined spaces. The activity concentration of radon-222 in the atmosphere can be measured by spot, continuous and integrated measurement methods with active or passive air sampling (
23、see ISO 11665-1). This part of ISO 11665 deals with radon-222 spot measurement methods. NOTE The origin of radon-222 and its short-lived decay products in the atmospheric environment and other measurement methods are described generally in ISO 11665-1. ISO 2012 All rights reserved v Measurement of r
24、adioactivity in the environment Air: radon-222 Part 6: Spot measurement method of the activity concentration 1 Scope This part of ISO 11665 describes radon-222 spot measurement methods. It gives indications for carrying out spot measurements, at the scale of a few minutes at a given place, of the ra
25、don activity concentration in open and confined atmospheres. This measurement method is intended for rapid assessment of the radon activity concentration in the air. The result cannot be extrapolated to an annual estimate of the radon activity concentration. This type of measurement is therefore not
26、 applicable for assessment of the annual exposure. The measurement method described is applicable to air samples with radon activity concentration greater than 50 Bq /m 3 . NOTE For example, using an appropriate device, the radon activity concentration can be spot measured in the soil and at the int
27、erface of a material with the atmosphere (see also ISO 11665-7). 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 docume
28、nt (including any amendments) applies. ISO 11665-1, Measurement of radioactivity in the environment Air: radon-222 Part 1: Origins of radon and its short-lived decay products and associated measurement methods ISO 11929, Determination of the characteristic limits (decision threshold, detection limit
29、 and limits of the confidence interval) for measurements of ionizing radiation Fundamentals and application ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories IEC 61577-1, Radiation protection instrumentation Radon and radon decay product measuring instrum
30、ents Part 1: General principles 3 T erms, definitions an d symbols 3.1 T erms and definition s For the purposes of this document, the terms and definitions given in ISO 11665-1 apply. INTERNATIONAL STANDARD ISO 11665-6:2012(E) ISO 2012 All rights reserved 1 ISO 11665-6:2012(E) 3.2 Symbols For the pu
31、rposes of this document, the symbols given in ISO 11665-1 and the following apply. C activity concentration, in becquerels per cubic metre C decision threshold of the activity concentration, in becquerels per cubic metre C # detection limit of the activity concentration, in becquerels per cubic metr
32、e C lower limit of the confidence interval of the activity concentration, in becquerels per cubic metre C upper limit of the confidence interval of the activity concentration, in becquerels per cubic metre U expanded uncertainty calculated by Uk u with k = 2 u standard uncertainty associated with th
33、e measurement result u rel relative standard uncertainty quantity to be measured 0 background level correction factor linked to the calibration factor 4 Principle Spot measurement of the radon activity concentration is based on the following elements: a) active grab sampling of a volume of air previ
34、ously filtered and representative of the atmosphere under investigation at time t; this pre-filtered sample is introduced into the detection chamber; b) measurement of the physical variable (photons, pulse counts and amplitude, etc.) linked to the radiation that is emitted by the radon and/or its de
35、cay products present in the detection chamber after sampling. Several measurement methods meet the requirements of this part of ISO 11665. They are basically distinguished by the type of physical quantity and how it is measured. The physical quantity and its related measurement may be as follows, fo
36、r example: photons emitted by a scintillating medium, such as ZnS(Ag), when excited by an alpha particle (see Annex A); gamma emission rates of the decay products 214 Pb and 214 Bi produced by the radon that is present in the sampled air volume. The measurement results can be available immediately o
37、r after a certain period of time. Due to the great variability of the radon activity concentration in time and space, the measurement result is representative of the radon activity concentration at the sampling time and the sampling place only. 5 Equipment The apparatus shall include the following:
38、a) a sampling device, including a filtering medium, for taking the air sample in the detection chamber; the role of the filtering medium is to stop the aerosols present in the air at the time of sampling, especially the solid radon decay products; 2 ISO 2012 All rights reserved ISO 11665-6:2012(E) b
39、) a device to pump the air for sampling if active sampling is required; c) the detection chamber; d) a measuring system adapted to the physical quantity. The necessary equipment for a specific measurement method is specified in Annex A. 6 Sampling 6.1 Sampling objective The sampling objective is to
40、introduce an ambient air sample into the detection chamber of the device during a short period of time of less than 1 h. 6.2 Sampling characteristics Sampling is active and may be carried out via pumping or suction in a detection chamber under vacuum. Grab sampling is representative of the radon act
41、ivity concentration at a given moment and a given place. An air sample adapted to the detection chamber of the measuring device used is taken directly in the atmosphere by pumping and filtering. The filtering medium shall stop the aerosol particles present in the air at the time of sampling, especia
42、lly the radon decay products. The sampling device shall not include components that trap radon (desiccants, etc.). 6.3 Sampling condition s 6.3.1 General Sampling shall be carried out as specified in ISO 11665-1. The sampling location and time (date and hour) shall be recorded. 6.3.2 Location of sam
43、pling place Grab sampling may be carried out in the atmosphere, inside a building, in the ground or at the interface between a material and the atmosphere, etc. The choice of each sampling location depends on the objectives sought (for example, verification of the homogeneity of the activity concent
44、rations in an environment or a search for anomalies, etc.). 6.3.3 Sampling duration Sampling is carried out over a short period of time. The sampling duration shall be less than one hour. 6.3.4 V olume of air sampled The volume of air sampled shall be determined accurately with a flow-meter correcte
45、d for the temperature and pressure variation (expressed in cubic metres at a standard pressure and temperature of 1,013 hPa and 0 C respectively) or by deducing it from a pressure measurement when sampling is carried out via suction (see Annex A). 7 Detection Detection shall be carried out using sil
46、ver-activated zinc sulphide ZnS(Ag) scintillation or gamma-ray spectrometry, as described in ISO 11665-1. ISO 2012 All rights reserved 3 ISO 11665-6:2012(E) 8 Measurement 8.1 Procedure Measurement shall be carried out as follows. a) Determine the background of the detection chamber. b) Select and lo
47、cate the measuring place. c) Using grab sampling, collect an air sample representative of the atmosphere under investigation. d) Record the location and time (date and hour) of sampling. e) Wait until short-lived decay products are in equilibrium with radon in the detection chamber (3 h). f) Measure
48、 the physical quantity emitted in the detection chamber with a suitable measuring chain. g) Record the time (date and hour) of measurement. h) Determine the activity concentration by calculation. The measurement procedure for the scintillation method is detailed in Annex A. 8.2 Influence quantities
49、Various quantities can lead to measurement bias that could induce non-representative results. Depending on the measurement method and the control of usual influence quantities specified in IEC 61577-1 and ISO 11665-1, the following quantities shall be considered in particular: a) the instrumental background noise; b) the presence of other gaseous radionuclide alpha-emitters or gamma-emitters in the detection chamber, including other radon isotopes and their decay products. Man
