ISO 11665-1-2012 Measurement of radioactivity in the environment - Air radon-222 - Part 1 Origins of radon and its short-lived decay products and associated mea.pdf

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1、 ISO 2012 Measurement of radioactivity in the environment Air: radon-222 Part 1: Origins of radon and its short-lived decay products and associated measurement methods Mesurage de la radioactivit dans lenvironnement Air: radon 222 Partie 1: Origine du radon et de ses descendants vie courte, et mthod

2、es de mesure associes INTERNATIONAL STANDARD ISO 11665-1 First edition 2012-07-15 Reference number ISO 11665-1:2012(E) ISO 11665-1:2012(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 reprodu

3、ced or utilized in any form or by any means, electronic or mechanical, 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

4、 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ISO 11665-1:2012(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 Symb

5、ols . 8 4 Principle . 9 5 Equipment . 9 6 Sampling 10 6.1 General .10 6.2 Sampling objective .10 6.3 Sampling characteristics .10 6.4 Sampling conditions . 11 7 Detection 12 7.1 Silver-activated zinc sulphide ZnS(Ag) scintillation 12 7.2 Gamma-ray spectrometry .13 7.3 Liquid scintillation .13 7.4 Ai

6、r ionization .13 7.5 Semi-conductor (alpha detection) 13 7.6 Solid-state nuclear track detectors (SSNTD) .13 7.7 Discharge of polarised surface inside an ionization chamber .13 8 Measurement 13 8.1 Methods .13 8.2 Influence quantities 14 8.3 Calibration .15 8.4 Quality control 15 9 Expression of res

7、ults .15 10 Test report .15 Annex A (informative) Radon and its decay products General information 17 Annex B (informative) Example of results of spot, integrated and continuous measurements of radon-222 activity concentration 25 Annex C (informative) Example of a test report .27 Bibliography .28 IS

8、O 11665-1:2012(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a sub

9、ject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (I

10、EC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical commit

11、tees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member 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

12、 held responsible for identifying any or all such patent rights. ISO 11665-1 was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies, and radiological protection, Subcommittee SC 2, Radiological protection. ISO 11665 consists of the following parts, under the general titl

13、e Measurement of radioactivity in the environment Air: radon-222: Part 1: Origins of radon and its short-lived decay products and associated measurement methods Part 2: Integrated measurement method for determining average potential alpha energy concentration of its short-lived decay products Part 3

14、: Spot measurement method of the potential alpha energy concentration of its short-lived decay products Part 4: Integrated measurement method for determining average activity concentration using passive sampling and delayed analysis Part 5: Continuous measurement method of the activity concentration

15、 Part 6: Spot measurement method of the activity concentration Part 7: Accumulation method for estimating surface exhalation rate Part 8: Methodologies for initial and additional investigations in buildings The following parts are under preparation: Part 9: Method for determining exhalation rate of

16、dense building materials P a r t 1 0 : Determination of diffusion coefficient in waterproof materials using activity concentration measurement iv ISO 2012 All rights reserved ISO 11665-1:2012(E) Introduction Radon isotopes 222, 220 and 219 are radioactive gases produced by the disintegration of radi

17、um isotopes 226, 224 and 223, which are decay products of uranium-238, thorium-232 and uranium-235 respectively, and are all found in the earths crust (see Annex A for further information). Solid elements, also radioactive, followed by stable lead are produced by radon disintegration 1 . Radon is co

18、nsidered a noble gas in the periodic table of elements, along with helium, argon, neon, krypton and xenon. 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 radon l

19、ie in its 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 2345 . Radon is today considered to be the main source of human expo

20、sure to natural radiation. The UNSCEAR (2006) report 6suggests 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 considered n

21、egligible (see Annex A). 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

22、 it depends 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 usually found in the continental environment are normally between a few bec

23、querels per cubic metre and several thousand becquerels per cubic metre. Activity concentrations of less than one becquerel per cubic metre may be observed in the oceanic environment. Radon activity concentrations vary inside houses from several tens of becquerels per cubic metre to several hundreds

24、 of becquerels per cubic metre 7 . Activity concentration can reach several thousands of becquerels per cubic metre in very confined spaces. Variations of a few nanojoules per cubic metre to several thousand nanojoules per cubic metre are observed for the potential alpha energy concentration of shor

25、t-lived radon decay products. ISO 11665 consists of 10 parts (see Figure 1) dealing with: measurement methods for radon-222 and its short-lived decay products (see ISO 11665-2, ISO 11665-3, ISO 11665-4, ISO 11665-5 and ISO 11665-6); NOTE 1 There are many methods for measuring the radon-222 activity

26、concentration and the potential alpha energy concentration of its short-lived decay products. The choice of measurement method will depend on the expected level of concentration and on the intended use of the data, such as scientific research and health-related assessments 89 . measurement methods f

27、or the radon-222 exhalation rate (see ISO 11665-7 and ISO 11665-9); NOTE 2 ISO 11665-7 refers back to ISO 11665-5 and ISO 11665-6. measurement methods for the radon-222 diffusion coefficient (see ISO 11665-10); methodologies for radon-222 measurements in buildings (see ISO 11665-8). NOTE 3 ISO 11665

28、-8 refers back to ISO 11665-4 for radon measurements for initial investigation purposes in a building and to ISO 11665-5, ISO 11665-6 and ISO 11665-7 for measurements for any additional investigation. ISO 2012 All rights reserved v ISO 11665-1:2012(E) ISO 11665-1 Origins of radon and its short-lived

29、 decay products and associated measurement methods MEASUREMENT APPLICATION ISO 11665-2 Integrated measurement method for determining average potential alpha energy concentration of its short-lived decay products ISO 11665-4 Integrated measurement method for determining average activity concentration

30、 using passive sampling and delayed analysis ISO 11665-3 Spot measurement method of the potential alpha energy concentration of its short-lived decay products ISO 11665-5 Continuous measurement method of the activity concentration ISO 11665-7 Accumulation method for estimating surface exhalation rat

31、e 11665-8 Methodologies for initial and additional investigations in buildings ISO 11665-6 Spot measurement method of the activity concentration 11665-9 Method for determining exhalation rate of dense building materials ISO 11665-10 Determination of diffusion coefficient in waterproof materials usin

32、g activity concentration measurement Figure 1 Structure of the ISO 11665 series vi ISO 2012 All rights reserved INTERNATIONAL STANDARD ISO 11665-1:2012(E) Measurement of radioactivity in the environment Air: radon-222 Part 1: Origins of radon and its short-lived decay products and associated measure

33、ment methods 1 Scope This part of ISO 11665 outlines guidance for measuring radon-222 activity concentration and the potential alpha energy concentration of its short-lived decay products in the air. The measurement methods fall into three categories: a) spot measurement methods; b) continuous measu

34、rement methods; c) integrated measurement methods. This part of ISO 11665 provides several methods commonly used for measuring radon-222 and its short-lived decay products in air. This part of ISO 11665 also provides guidance on the determination of the inherent uncertainty linked to the measurement

35、 methods described in its different parts. 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 amen

36、dments) applies. 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 instruments Part 1: General principles IEC 61577-2, Radiation protection instrumentation Radon and

37、 radon decay product measuring instruments Part 2: Specific requirements for radon measuring instruments IEC 61577-3, Radiation protection instrumentation Radon and radon decay product measuring instruments Part 3: Specific requirements for radon decay product measuring instruments 3 T erms, definit

38、ions an d symbols 3.1 T erms and definition s For the purposes of this document, the following terms and definitions apply. 3.1.1 active sampling sampling using active devices like pumps for sampling the atmosphere IEC 61577-1:2006 ISO 2012 All rights reserved 1 ISO 11665-1:2012(E) 3.1.2 activity di

39、sintegration rate number of spontaneous nuclear disintegrations occurring in a given quantity of material during a suitably small interval of time divided by that interval of time ISO 921:1997, term 23 NOTE 1 Activity, A, is expressed by the relationship given in Formula (1): AN (1) where is the dec

40、ay constant per second; N is the number of atoms. NOTE 2 The decay constant is linked to the radioactive half-life by the relationship: ln /2 12 T(2) where T 1/2is the radioactive half-life, in seconds. 3.1.3 activity concentration activity per unit volume IEC 61577-1:2006 3.1.4 attached fraction fr

41、action of the potential alpha energy concentration of short-lived decay products that is attached to the ambient aerosol IEC 61577-1:2006 NOTE The sizes of the carrier aerosol to which most of the short-lived decay products are attached are generally in the 0,1 m to 0,3 m range of median values. 3.1

42、.5 average activity concentration exposure to activity concentration divided by the sampling duration 3.1.6 average potential alpha energy concentration exposure to potential alpha energy concentration divided by the sampling duration 3.1.7 b a c kg r o u n d no i se signals caused by something othe

43、r than the radiation to be detected NOTE A distinction can be made between signals caused by radiation from sources inside or outside the detector other than those targeted for the measurements and signals caused by defects in the detection system electronic circuits and their electrical power suppl

44、y. 2 ISO 2012 All rights reserved ISO 11665-1:2012(E) 3.1.8 continuous measurement measurement obtained by taking a sample continuously (or at integration intervals typically in range of 1 min to 120 min) with simultaneous or slightly delayed analysis NOTE 1 The sampling duration shall be adapted to

45、 the dynamics of the phenomenon studied to monitor the evolution of radon activity concentration over time. NOTE 2 See Annex B for further information. 3.1.9 diffusion length distance crossed by an atom due to diffusion forces before decaying NOTE Diffusion length, l, is expressed by the relationshi

46、p given in Formula (3): l D 1 2(3) where D is the diffusion coefficient, in square metres per second; is the decay constant per second. 3.1.10 e q uilib r iu m f ac tor ratio of the potential alpha energy concentration of short-lived radon decay products in a given volume of air to the potential alp

47、ha energy concentration of these decay products if these are in radioactive equilibrium with radon in the same volume of air NOTE 1 The short-lived 222 Rn decay products present in an atmosphere are very rarely in radioactive equilibrium with their parent (through being trapped on the walls or elimi

48、nated by an air renewal system, for example) and the equilibrium factor is used to qualify this state of “non-equilibrium”. NOTE 2 The equilibrium factor is between 0 and 1. The equilibrium factor in buildings typically varies between 0,1 and 0,9, with an average value equal to 0,4 46 . NOTE 3 The e

49、quilibrium factor, F eq , is expressed by Formula (4): F E C eq PAEC,222 Rn Rn 55 71 0 9 222 ,(4) where E PAEC,222 Rn is the potential alpha energy concentration of 222 Rn, in joules per cubic metre; 55 71 0 9 , is the potential alpha energy concentration of the short-lived 222 Rn decay products for 1 Bq of 222 Rn in equilibrium with its short-lived decay products, in joules per becquerel; C 222 Rn is the activity concentrati