1、 ISO 2012 Measurement of radioactivity in the environment Air: radon-222 Part 5: Continuous measurement method of the activity concentration Mesurage de la radioactivit dans lenvironnement Air: radon 222 Partie 5: Mthode de mesure en continu de lactivit volumique INTERNATIONAL STANDARD ISO 11665-5 F
2、irst edition 2012-07-15 Reference number ISO 11665-5:2012(E) ISO 11665-5:2012(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
3、 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 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web w
4、ww.iso.org Published in Switzerland ISO 11665-5:2012(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 . 1 4 Principle . 2 5 Equipment . 3 6 Sampling 3 6.1 S
5、ampling objective . 3 6.2 Sampling characteristics . 3 6.3 Sampling conditions . 3 7 Detection 4 8 Measurement 4 8.1 Procedure 4 8.2 Influence quantities 4 8.3 Calibration . 4 9 Expression of results . 5 9.1 Radon activity concentration . 5 9.2 Standard uncertainty 5 9.3 Decision threshold and detec
6、tion limit . 5 9.4 Limits of the confidence interval . 5 10 Test report . 5 Annex A (informative) Measurement method using a vented ionization chamber and a current ionization chamber . 7 Bibliography .13 ISO 11665-5:2012(E) Foreword ISO (the International Organization for Standardization) is a worl
7、dwide 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 subject for which a technical committee has been established has the right to be represented on
8、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 (IEC) on all matters of electrotechnical standardization. International Standards are drafted i
9、n 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 committees are circulated to the member bodies for voting. Publication as an International Standard
10、 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 held responsible for identifying any or all such patent rights. ISO 11665-5 was prepared by
11、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 title Measurement of radioactivity in the environment Air: radon-222: Part 1: Origins of radon an
12、d 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: Spot measurement method of the potential alpha energy concentration of its short-lived deca
13、y 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 Part 6: Spot measurement method of the activity concentration Part 7: Accumulation method fo
14、r 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 dense building materials P a r t 1 0 : Determination of diffusion coefficient in waterproof m
15、aterials using activity concentration measurement iv ISO 2012 All rights reserved ISO 11665-5:2012(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 uraniu
16、m-235 respectively, and are all found in the earths 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.
17、). The potential effects on human health of radon 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 t
18、oday considered to be the main source of human 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 i
19、sotope 220 (4 %), while isotope 219 is considered negligible. For this reason, references to radon in this part of 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 t
20、remendously from one area to another, as 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 area where individuals are exposed. The values commonly found in the continental en
21、vironment are usually between a few becquerels per 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 can vary from several tens of becqu
22、erels per cubic metre to several hundreds of becquerels 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 measurem
23、ent methods with active or passive air sampling (see ISO 11665-1). This part of ISO 11665 deals with continuous measurement methods for radon-222. NOTE The origin of radon-222 and its short-lived decay products in the atmospheric environment and other measurement methods are described generally in I
24、SO 11665-1. ISO 2012 All rights reserved v Measurement of radioactivity in the environment Air: radon-222 Part 5: Continuous measurement method of the activity concentration 1 Scope This part of ISO 11665 describes continuous measurement methods for radon-222. It gives indications for continuous mea
25、suring of the temporal variations of radon activity concentration in open or confined atmospheres. This part of ISO 11665 is intended for assessing temporal changes in radon activity concentration in the environment, in public buildings, in homes and in work places, as a function of influence quanti
26、ties such as ventilation and/or meteorological conditions. The measurement method described is applicable to air samples with radon activity concentration greater than 5 Bq/m 3 . 2 Normative references The following referenced documents are indispensable for the application of this document. For dat
27、ed references, only the edition cited applies. For undated references, the latest edition of the referenced document (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 associa
28、ted measurement methods ISO 11929, Determination of the characteristic limits (decision threshold, detection limit 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 calibrat
29、ion 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 radon decay product measuring instruments Part 2: Specific requirements for radon measuring in
30、struments 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. 3.2 Symbols For the purposes of this document, the symbols given in ISO 11665-1 and the following apply. C activity concentration, in becq
31、uerels per cubic metre C decision threshold of the activity concentration, in becquerels per cubic metre INTERNATIONAL STANDARD ISO 11665-5:2012(E) ISO 2012 All rights reserved 1 ISO 11665-5:2012(E) C # detection limit of the activity concentration, in becquerels per cubic metre C lower limit of the
32、 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 the measurement result u
33、 rel relative standard uncertainty quantity to be measured 0 background level correction factor linked to the calibration factor and climatic correction factors 4 Principle Continuous measurement of the radon activity concentration is based on the following elements: a) continuous in situ sampling o
34、f a volume of air previously filtered and representative of the atmosphere under investigation; b) continuous detection of radiations emitted by radon and its decay products accumulated in the detection chamber. Several measurement methods meet the requirements of this part of ISO 11665. They are ba
35、sically distinguished by the type of physical quantity and how it is detected. The physical quantity and its related detection may be as follows, for example: ionization current produced by several tens of thousands of ion pairs created by each alpha particle emitted by the radon that is present in
36、the detection chamber and its decay products formed therein (see Annex A); charges produced in a solid semi-conductor medium (silicon) by ionization from alpha particles of radon and its decay products; the charges are detected by related electronics. Measurement results are instantly available. A m
37、ean or integrated value can be obtained through appropriate processing based on an integration interval compatible with the phenomenon studied but in all cases less than or equal to one hour. In order to monitor the temporal variation of radon activity concentration, the measurement period must be c
38、ompatible with the dynamics of the phenomenon studied. For example, the minimum significant period for detecting daily variations is approximately one week. Continuous monitoring allows for the assessment of temporal changes in radon activity concentration. For measurements performed outdoors, the s
39、eason and climatic conditions shall be taken into account. For measurements performed inside a building, the lifestyles of its inhabitants, the level at which the measurement place is located (basement, ground floor, upper levels) and the natural ventilation characteristics (condition of doors and w
40、indows, open or closed) shall be taken into account. 2 ISO 2012 All rights reserved ISO 11665-5:2012(E) 5 Equipment The apparatus shall include the following: a) a sampling device, including a filtering medium, for taking the air sample in the detection chamber, a device to pump the air for sampling
41、 if active sampling is necessary, and the detection chamber; b) a measuring system adapted to the physical quantity to be measured. The instrument used for measurement shall satisfy the requirements of IEC 61577-2. An example of the equipment (ionization chamber) for a specific measurement method is
42、 given in Annex A. 6 Sampling 6.1 Sampling objective The sampling objective is to place an air sample representative of the atmosphere under investigation in continuous contact with the detector. 6.2 Sampling characteristics Sampling may be passive (natural diffusion) or active (pumping). Sampling s
43、hall be performed through a filtering medium which prevents access of aerosol particles present in the air at the time of sampling, especially radon decay products. The filter shall not trap radon gas. The sampling system shall be used under conditions that do not cause clogging of the filter (this
44、would result in a modification of the measurement conditions, e.g. decrease of gas quantity sampled due to pressure drop in measurement chamber). In case of clogging during sampling by pumping, the pressure drop might increase, leading to a degradation in the performance of the measurement system, a
45、nd possibly resulting in the perforation of the filter. Clogging during sampling by natural diffusion can lead to the non-renewal of air in the detection chamber. 6.3 Sampling condition s 6.3.1 General Sampling shall be carried out as specified in ISO 11665-1. The sampling location, date and time sh
46、all be recorded. 6.3.2 Installation of sampl ing device Installation of the sampling device shall be carried out as specified in ISO 11665-1. 6.3.3 Sampling duration For continuous sampling, the sampling duration corresponds to the measurement period, which shall be compatible with the dynamics of t
47、he phenomenon studied. 6.3.4 Integration interval The integration interval determines the time resolution of the measurement. Different parameters such as the expected radon activity concentration or dynamics of radon level changes need to be taken into account when selecting the appropriate integra
48、tion interval. ISO 2012 All rights reserved 3 ISO 11665-5:2012(E) 6.3.5 V olume of air sampled For active sampling, the volume of air sampled shall be measured by a flow-meter corrected for the temperature and pressure variation (expressed in cubic metres at a standard pressure and temperature of 1,
49、013 hPa and 0 C respectively). For passive sampling, direct measurement of the air volume sampled is not necessary; a calibration factor (activity per unit volume) shall be used. 7 Detection Detection shall be carried out using a suitable method as outlined in ISO 11665-1. 8 Measurement 8.1 Procedure The measurement procedure is specific to the detection method used. An example of a measurement procedure using an ionization chamber is given in Annex A. 8.2 Influence quan
