1、 American National Standard ANSI/HPS 43.8-2008 Classification of Industrial Ionizing Radiation Gauging Devices Approved March 2008 Reaffirmed September 2013 American National Standards Institute, Inc. Published by Health Physics Society 1313 Dolley Madison Blvd. Suite 402 McLean, VA 22101 Copyright
2、2008 by the Health Physics Society. All rights reserved. No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without prior written permission of the publisher. Printed in the United States of America ANSI/HPS N43.8-2008 (R2013) iii Members of th
3、e original subcommittee that produced ANSI N538: John R. Dukes (chairman) A. LaMastra D.A. Smith J. Bell C.R. Landfried D. Steele H.L. Cook E.M. Pollock D. Stephens H.H. Dooley T. Pratt A.C. Tapert E.H. Eisenhower W. Prendergast R.G. Wissink W.G. Hendrick E.F. Ridout D. Keller M. Shupe Members of Su
4、bcommittee N43.3.2 who were active during the review for standard ANSI N43.8-1986/88: John R. Dukes (chairman) B.J. Jackson W. Prendergast H.L. Cook A. LaMastra R.G. Wissink E.H. Eisenhower C.R. Landfried W.G. Hendrick E.M. Pollock Members of Subcommittee N43-8 who were active during review of stand
5、ard ANSI/HPS N43.8-2001: John R. Dukes (chairman) James L. Hovey, Jr. Thomas W. Rich ABB Industrial Systems Valmet Automation USNRC (retired) (retired) Gary W. Robertson Gary L. Caines Anthony LaMastra Nuclear Research Corp Honeywell Inc. Health Physics Associates Robert G. Wissink Hugh W. Evans Els
6、a Nimmo 3-M AEA Technology / QSA Honeywell-Measurex Members of Subcommittee N43.8 who were active during review and updating of the current standard: John R. Dukes (chairman) ABB Inc. (retired) Jonathan Fortkamp ABB Inc. John Selby (retired) Bill Thomas Integrated Environmental Management Charles Ba
7、yles Automation gauging devices; devices; ionizing radiation; radiation measurements; radiation safety; standard vi Contents Foreword viii 1.0 Scope .1 2.0 Definitions .1 3.0 Safety Features and Requirements2 3.1 Source Integrity2 3.2 Source Retention3 3.3 Source Access.3 3.4 Integral Radiation Shie
8、lds3 3.5 Useful-beam Controls3 3.6 ON-OFF Indicators 3 3.7 Interlocks and Barricades .4 3.8 Labels 4 3.9 Instructions.5 4.0 Conditions of Use 5 4.1 Auxiliary Shielding and Barriers 5 4.2 Serviceability/Maintainability .5 4.3 Administrative Controls .5 4.4 Licensing and Registration.6 5.0 Shipping.6
9、5.1 Packaging and Transportation.6 5.2 Temporary Shielding/Shutter Restraint.6 6.0 Device Safety Performance Classification 7 6.1 Device Classification7 6.2 Other Conditions9 7.0 Testing Procedures for Table 1 .10 7.1 General 10 7.2 Use Condition Temperature Test. 10 7.3 Stray Radiation 10 7.4 Accid
10、ent Condition Fire Tests .13 8.0 Quality Assurance and Control13 vii 9.0 National and International Standards Referred to in This Document13 Figures Figure 1-1. Isodistance contours15 Figure 2-1. Density gauge15 Figure 2-2. Level gauge.16 Figure 2-3. Transmission type gauge (beta, photon, neutron).
11、16 Figure 2-4. Backscatter type gauge utilizing scattering backer (beta, photon) 17 Figure 2-5. Backscatter type gauge utilizing process material for scattering surface17 Figure 2-6. Neutron backscatter gauge 18 Tables Table 1. Classification of device safety performance standards8 Table 2. Standard
12、 conditions for stray radiation tests14 Annexes Annex A Radiation Measurement 19 Annex B Quality Assurance and Control .20 viii Foreword (This foreword is not part of American National Standard ANSI/HPS N43.8-2008) In 1972, the U.S. Atomic Energy Commission identified a number of areas in the regula
13、tory process for which nuclear standards were desired. An appeal was made to the Priorities Committee of the ANSI Nuclear Technical Advisory Board for support, and Subcommittee N43-3.2 was activated under the sponsorship of the National Bureau of Standards to develop this standard for gauging device
14、s. Work on the standard was begun in 1973, and the draft proposal was completed in 1976. The standard was ultimately published in 1979 as ANSI N538-1979. It was also identified as NBS Handbook 129. This standard establishes a system for classification for gauging devices that use sealed radioisotope
15、s or machine-generated sources of radiation based on performance specifications relating to radiation safety. In addition to specific tests for use conditions and accident conditions (fire), guidelines for other safety features and considerations are presented. This standard does not apply to the me
16、asurement performance of gauging devices. ANSI N538-1979 was submitted to ISO/TC 85 and was merged with a French national standard to produce ISO 7205-1986, Radionuclide gauges Gauges designed for permanent installation. Reaffirmed and Renumbered as ANSI N43.8 In 1985, ANSI N538 was reviewed by ANSI
17、 Subcommittees N43.2 and N43. In 1986 it was reaffirmed without change. It was subsequently renumbered and reissued as ANSI N43.8 and reaffirmed again in 1988. Revised Standard ANSI/HPS N43.8-2001 Review of ANSI N43.8 was undertaken again in 1994. Subcommittee N43.2 identified the need for numerous
18、changes to make it compatible with the new 10 CFR 20 and other changes in the field. After a number of review sessions with extensive comments, a final consensus was reached in February 1999. The original document was recreated in digital form. Iit was revised again to convert it to the new ANSI sty
19、le and was submitted to N43 and HPS for review and voting. It was finally published in 2001. Revised Standard ANSI/HPS N43.8-2008 Formation of the five-year review subcommittee for ANSI N43.8 was initiated on February 20, 2006. Five subcommittee reviews were held during 2006. One additional review w
20、as held during 2007. The scope was broadened to include devices with any machine-generated source of radiation, not just x-ray tubes and radionuclide sources. Section 3.2 is new and a number of definitions were added. References were updated, errors were corrected, text was clarified, and SI units w
21、ere made dominant throughout. The document was submitted to N43 for ballot on April 1, 2007. AMERICAN NATIONAL STANDARD ANSI/HPS N43.8-2008 1 Classification of Industrial Ionizing Radiation Gauging Devices 1.0 Scope This standard applies to radiation gauging devices, commonly called devices, that us
22、e sealed radioactive sources or machine-generated sources for the determination or control of thickness, density, level, interface location, particle size distribution, or qualitative or quantitative chemical composition. The standard establishes a system for classification of the gauging devices ba
23、sed on performance specifications relating to radiation safety. In addition to specific tests for use conditions and accident conditions (fire), guidelines for other safety features and considerations are presented. This standard does not apply to the measurement performance of gauging devices. 2.0
24、Definitions accessible surface: any surface of the device that can readily be reached by any part of the human body without the use of tools or without the removal of any part of the device. ALARA: acronym for “as low as reasonably achievable,” which means making every reasonable effort to maintain
25、exposures to radiation as low as practical, consistent with the purpose for which the activity is undertaken, taking into account the state of technology and economic and social considerations. dose rates shallow dose equivalent rate (7 mg cm2): For x-ray, gamma, and charged-particle radiation, the
26、radiation level in Sv h1(mrem h1) measured with a detector having a total window and absorber density thickness no greater than 7 mg cm2of tissue equivalent material. All neutron radiation levels in Sv h1(mrem h1) are also included. eye dose equivalent rate (300 mg cm2): For x-ray, gamma, and charge
27、d-particle radiation, the radiation level in Sv h1(mrem h1) measured with a detector having a total window and absorber density thickness no greater than 300 mg cm2and no less than 270 mg cm2of tissue equivalent material. All neutron radiation levels in Sv h1(mrem h1) are also included. deep dose eq
28、uivalent rate (1,000 mg cm2): For x-ray, gamma, and charged-particle radiation, the radiation level in Sv h1(mrem h1) measured with a detector having a total window and absorber density thickness no greater than 1,000 mg cm2and no less than 900 mg cm2of tissue equivalent material. All neutron radiat
29、ion levels in Sv h1(mrem h1) are also included. dummy source: facsimile of a radioactive source of exactly the same material and construction as a sealed source but containing, in place of the radioactive material, a substance resembling it as closely as practicable in terms of physical and chemical
30、 properties. gauging device (device): a mechanism containing a source of ionizing radiation that is designed and manufactured for the purpose of determining or controlling thickness, density, level, interface location, or qualitative or quantitative chemical composition of materials. It may include
31、components such as radiation shields, useful-beam controls, and other safety features in order to meet the requirements or specifications of this standard. interlock: an electrical and/or mechanical safety feature designed to preclude access to an area of radiation hazard either by preventing entry
32、or by automatically removing the hazard. isodistance contour: the imaginary surface around a device at a specified distance from the nearest accessible surfaces. For practical reasons in this standard, the literal interpretation has been simplified as defined in Section 7.3.2 and Figures 1-1 and 2-1
33、 through 2-6. leakage radiation: all radiation coming from within the source housing, except the useful beam. machine-generated source: a non-radioactive component that is used as a source of ionizing radiation (including x-ray tubes, particle accelerators, neutron generators, etc.). Note: Some mach
34、ine-generated sources may contain a very small amount of radioactive material. measuring gap (air gap): the distance between the source housing and the detector housing for ANSI/HPS N43.8-2008 2 a transmission gauging device, or the distance between the source and detector housing and the process be
35、ing measured for a backscatter gauging device. nearest accessible surface: the accessible surface(s) of the device closest to the point or region of interest. protective barrier: a structure or obstacle to limit access of personnel to fields of radiation. A protective barrier is distinguished from a
36、 radiation shield in that it limits personnel access to radiation sources, whereas a radiation shield reduces radiation intensity. radiation shield: the material used intentionally to reduce the intensity of radiation entering a region. radiation source (source): a source of ionizing radiation in wh
37、ich the radiation is produced either by radioactive material or by radiation-generating equipment. radioactive source: any quantity of radioactive material that is intended for use as a source of ionizing radiation. safety features: properties of a device designed to preclude unintended exposure to
38、sources of radiation. Safety features may include, but are not limited to, radiation source containment, useful-beam controls (shutters), radiation beam collimation, shielding, beam ON-OFF indicators, key-locked power ON-OFF switches, safety interlocks, barriers, admini-strative controls, etc. scatt
39、ered radiation: radiation that, during passage through matter, has been deviated in direction (it may also have been modified by a decrease in energy). source OFF (beam off): the condition for a device equipped with useful-beam controls when the useful beam is properly minimized by actuating the con
40、trol. source ON (beam on): the condition for a device equipped with useful-beam controls when the useful beam is properly maximized by actuating the control. source holder: a device used to support and retain the source. source housing: an enclosure containing or incorporating the source, source hol
41、der, and means for attenuation of the radiation. stray radiation: the sum of leakage and scattered radiation. useful beam: radiation that passes through the window, aperture, cone, or other collimating device of the source housing; sometimes called primary beam. user: a company, agency, or individua
42、l who, in the course of business, uses devices defined by this standard for their intended purposes. x-ray tube source: a common type of machine-generated source in which the ionizing radiation is produced by bombarding a metallic target with energetic electrons in an x-ray tube. X-ray tube sources
43、produce radiation that is electro-magnetic and have wavelengths shorter than those of ultraviolet light. 3.0 Safety Features and Requirements 3.1 Source Integrity 3.1.1 Radioactive Source The radioactive material shall be in the form of a sealed source that shall be classified in accordance with the
44、 American National Standard ANSI/HPS N43.6-2007, “Sealed Radioactive Sources Classification.” Sealed source leak tests shall be performed periodically to verify containment of the radioactive material. The leak test frequency should be based on the source capsule construction, conditions of use, and
45、 degree of source protection provided by the device. Sealed source leak tests should be conducted at the nearest available access to the sealed source or likely areas of contamination leakage without unnecessarily exposing personnel. Comprehensive leak testing information is contained in ISO 9978 an
46、d other standards. 3.1.2 Machine-Generated Source The source shall be such that no radiation is emitted except by application of electrical power to the source. Provisions shall be made to limit both the current through the source and the ANSI/HPS N43.8-2008 3 voltage across the source, so that radi
47、ation levels do not exceed the device classification under use conditions or through circuit component failures. Provisions shall be made to ensure the high voltage is automatically disabled before loss of any integral shielding in the event of fire or abnormal elevated temperatures. This provision
48、exempts machine-generated sources from accident condition (fire) classification. 3.2. Source Retention The device shall be designed to retain its source(s) during normal and extreme conditions of use. It shall also be able to maintain the source(s) in a shielded condition under these conditions. In
49、addition, radioactive sources shall be retained under likely accident conditions. 3.3 Source Access The device shall be designed to restrict access to the source of radiation by personnel who are not properly trained and licensed or registered for such access. 3.4 Integral Radiation Shields Shielding that is part of the device shall reduce the radiation emitted by the source to the levels required by the device classification. In addition, the manufacturer should design the shielding in such a manner that
