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1、International Standard INTERNATIONAL ORGANIZATION FOR STANDARDIZATlON*MEYHAPOAHAR OPrAHH3AUMR fl0 CTAHPTH3AUMM*ORGANlSATlON INTERNATIONALE DE NORMALISATION Radionuclide gauges - Gauges designed for permanent installation Jauges r) radiot%ments - Apparels destinh i) Btre instal/c!s B paste fixe First
2、 edition - 1966-12-15 UDC 621.039567 : 621.37 Ref. No. IS0 7205-1966 (E) Descriptors : nuclear energy, radiation measuring instruments, radio-element gauges, classification, specifications, safety requirements, tests. Price based on 15 pages Copyright International Organization for Standardization P
3、rovided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:00:15 MDTNo reproduction or networking permitted without license from IHS -,-,- Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national s
4、tandards bodies (IS0 member bodies). The work of preparing International Standards is normafly carried out through IS0 technicat 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
5、organizations, govern- mental and non-governmental, in liaison with ISO, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as international Standards by the IS0 Council. They are appr
6、oved in accordance with IS0 procedures requiring at least 75 % approval by the member bodies voting. International Standard IS0 7205 was prepared by Technical Committee ISO/TC 85, Nuclear energy. Users should note that all International Standards undergo revision from time to time and that any refer
7、ence made herein to any other International Standard implies its latest edition, unless otherwise stated. 0 International Organfzation for Standardization, 1999 0 Printed in Switzerland ii Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA T
8、echnical Standards 1/9972545001 Not for Resale, 04/20/2007 07:00:15 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 7205-1986 (El Contents Scope and field of application References Definitions Classification of gauges . General considerations Classification of gauges ac
9、cording to safety performance Testmethods Gauge codes and markings Accompanying documents . Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/99
10、72545001 Not for Resale, 04/20/2007 07:00:15 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD IS0 72051986 (E) Radionuclide gauges - Gauges designed for permanent installation 1 Scope and field of application The purpose of this International Standard
11、is to establish the following characteristics for radionuclide gauges designed for permanent installation: a) a classification of the gauges and shielding devices; b) technical construction and performance requirements for radiation protection when using a radioactive source; c) control and test met
12、hods to verify the compliance of the gauges with those requirements; d) indications to be shown on the gauges. In addition to the construction requirements above, the gauges shall comply with existing regulations. This International Standard does not apply to gauges which, because of their design, a
13、nd due to the nature and the low ac- tivity of the sources they contain, are not subject to general rules regarding supply and possession of artificial radionuclides nor does it apply to ion generators (smoke detectors, static eliminators, etc.). 2 References IS0 361, Basic ionizing radiation symbol
14、. I SO 921, Nuclear energy glossary. IS0 1677, Sealed radioactive sources - General. IS0 2919, Sealed radioactive sources - Classification. IS0 3768, Metallic coatings - Neutral salt spray test iNSS tes tl. 3 Definitions For the purposes of this International Standard, the definitions given in IS0 9
15、21 and the following definitions apply. 3.1 radionuclide gauge; gauge: A control and measuring device activated by the radiation emitted by one or more sealed radioactive sources. It includes a source housing and a detector housing (or a combined source/detector housing). 3.2 source housing: Enclosu
16、re containing the radioactive source(s), a source holder and means for attenuating the radiation, 3.3 detector housing: Enclosure containing the radiation detector. 3.4 source/detector housing: Combined source/detector housing forming a rigid assembly, the two units being either coupled or contained
17、 in the same enclosure. 3.5 source holder: Device used to support and contain the sealed source. 3.6 useful beam: Radiation passing through the window, aperture, cone or other collimation device of the source housing Isometimes called “primary beam”). 3.7 radionuclide gauge for permanent installatio
18、n: Instrument designed to be installed in a fixed location. The detector housing and the source housing may be fixed or mobile. Mobility is limited and predetermined by the operations involved. 1 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee
19、=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:00:15 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 7205-1986 (El 4 Classification of gauges 4,1 Classification on the basis of the mobility of components Gauges are classified according to two main
20、categories, based on their mobility: al Gauges having two components (source housing and detector housing1 which are fixed on the structure of the industrial installation involved. Examples: Certain level gauges, certain thickness gauges. They are called fixed gauges on permanent installations. b1 G
21、auges in which at least one of the ponents is movable on the structure of the industrial installation where involved. Examplss: Travelling gauges, C-frame gauges. They are called mobile gauges on permanent installations. 4.2 Classification according to degree of collimation of the beam Radionuclide
22、gauges for permanent installation belong to one of the categories described in 4.2.1 and 4.2.2, depending on the degree of collimation of the beam radiated by the source housing. The categories are illustrated in figure 1. 4.2.1 Category A: Gauges with restricted beam Category A comprises gauges equ
23、ipped with a device for col- limation of radiation from the radioactive source(s), restricting one or more useful beams. The gauges shall be designed so that radiation within the solid angles formed by the collimator and all points on the active sur- face of the source are intercepted by the detecto
24、r housing or any other fixed absorber. In the case of back-scatter and X-ray fluorescence gauges, interception of primary radiation and back-scattered radiation shall be possible. 4,2.1.1 Sub-category Al Sub-category Al comprises those gauges in which the radio- active source, when in the operating
25、position, and the detector restrict a constant volume, i.e, either both parts of the device occupy fixed positions in relation to a fixed point on the installa- tion or both parts constitute one rigid assembly. Examples: Fixed-value level control and level-indication density gauges, C-frame thicknes
26、s gauges, fixed thickness gauges, shielded back-scatter gauges. 4,2,1.2 Sub-category A2 restrict a constant volume, the motion of both parts being mutually dependent. Txammples: Level follower or detection level control with varying set-point, thickness gauges also called “travelling gauges”. 4,2.1.
27、3 Sub-category A3 Sub-category A3 comprises those gauges in which the movements of the source housing and/or the detector housing on fixed axes are mutually dependent. Examples: Safety alignment gauges, safety gauges on travel- ling cranes. 4,2.2 Category B: Gauges without restricted beam Category B
28、 comprises gauges without a collimation device or gauges in which the collimator does not comply with the requirements for category A gauges. In the case of back-scatter and X-ray fluorescence gauges, interception of the primary radiation and back-scattered radia- tion is not complete, particularly
29、in the absence of material to be investigated. 4.2.2.1 Sub-category 91 Sub-category Bl comprises those gauges in which the radio- active source, when in the operating position, and the detector(s) occupy fixed positions in relation to one another. Examples: Neutron moisture gauges, back-scatter gaug
30、es without associated shield. 4.2.2.2 Sub-category 82: Ejection equipment Sub-category 82 comprises those gauges in which the detector occupies a fixed position, the source being ejected to a suitable location for measuring purposes, during the time required for measuring or control. Examples: Compa
31、cting control devices, density gauges used in chemical plants. 4.2.2,3 Sub-category B3 Sub-category 83 comprises those gauges in which the source holder moves inside the installation, depending on parameters to be controlled and measured, and the detector moves on the outside of the installation. Ex
32、amples; Position control of a mobile part inside an installa- tion, floats containing a source, safety alignment gauges, safety gauges on travelling cranes. 4.3 Classification as a function of safety performance Sub-category A2 comprises those gauges in which the radio- active source, when in the op
33、erating position, and the detector See clause 6, 2 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:00:15 MDTNo reproduction or networking permitted without license from IHS -,
34、-,- IS0 7205-1666 (E) 5 General considerations The source housing and the detector housing shall provide several variable functions according to the category of gauge involved, which all contribute to safety. Such functions, for each sub-category, are shown in table 2. 5.1 Radioactive source The rad
35、ioactive source(s) shall be seated, in accordance with the requirements of IS0 2919. 5.2 Source housing The source housing shall be designed in such a way that it will comply, for each type of gauge, with the requirements laid down in 5.2.1 to 5.2.4, in accordance with the functions shown in table 2
36、. 5.2.1 Source holder The fixed or mobile source holder shall a) allow for easy positioning of the radioactive source; b) provide means for fixing the source properly in order to prevent its loss; c be designed in such a way as to prevent it being dismantled by unqualified persons (for example, by p
37、lacing it in an enclosure provided with a safety lock or by making it necessary to use a specially designed tool to open it - in cases where it is impossible to eliminate access to the source holder, the device used for fastening the source in the holder shall at least be fitted with a lead safety s
38、eal; d) allow for its proper positioning in the source housing under safe radiological and containment conditions; el provide, under normal service conditions, protection of the radioactive source against impacts which could damage it, if no other means are provided in the gauge for such pro- tectio
39、n; f) ensure protection of the radioactive source against attacks of physical or chemical origin - under normal service conditions specified by the manufacturer for gauges of sub-categories 82 and B3, - when service conditions make it necessary for other sub-categories. 5.2.2 Restriction of useful b
40、eam The source housing in category A gauges shall restrict the useful beam in such a way that for the maximum source- detector distance specified by the manufacturer, the solid angle formed by the centre of the source and the collimator does not extend beyond the detector or its absorbing shields. I
41、f the source housing is designed to accommodate several col- limators which form different solid angles, the manufacturer shall indicate, for each, the maximum source-detector distance, In the case of category B gauges, it is recommended that the source holder be designed in such a way as to reduce
42、suffi- ciently the dose equivalent rate, outside the useful beam, in a solid angle as required to ensure the protection of the operator. 5.2.3 Shield against ionizing radiation The source housing of category A gauges shall ensure com- pliance with the dose equivalent rates corresponding to the prope
43、r gauge class (see 6.2 and table 3). In the case of installations with mobile sources, category B gauges shall include a storage container for the source and the source holder, so that when the radioactive source is not in the measuring position, dose equivalent rates corresponding to the class of g
44、auge involved will be met (see 6.3 and table 3). The storage container shall form an integral part of the installa- tion in the case of gauges of sub-categories 82 and 83; sub- category 81 gauges are not required to be equipped with an integral storage container. If the container is constructed with
45、 materials which are com- bustible, oxidizible, easily fusible or volatile, these shall be enclosed in one or more sealed envelopes strong enough to retain their shielding properties under the conditions specified in 7.5. 5.2.4 Shutter for the useful beam The source housing in category A gauges as w
46、ell as the storage container in category B gauges, if any, shall be equipped with a device integral with the source housing to intercept the beam, and thus ensure, for the class in question, compliance with the dose equivalent rates laid down in table 3 (see note 21, with the shutter closed. If this
47、 device is remote-controlled or servo-controlled, any defect in the control circuit or the servo-control circuit shall automatically close the device. The shutters shall be classified, as indicated by the manufac- turer on the operating and maintenance instructions provided on the gauge, according t
48、o one of the groups described in 5.2.4.1 to 5.2.4.3. 5.2.4.1 Group 1: Shutters for maintenance This group comprises shutters designed to operate under cer- tain conditions and solely during maintenance or servicing of the gauge or installation. 5.2,4.2 Group 2: Shutters used during operations (start
49、- up/shut-down) This group comprises shutters designed to operate on start-up and shut-down of the installation in which the gauge is incor- porated. 3 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:00:15 MDTNo reproduction or network