1、ANSI/HPS N13.52-1999 American National Standard Personnel Neutron Dosimeters (Neutron Energies Less Than 20 MeV) Approved October 26, 1999 Reaffirmed: August 3, 2010 American National Standards Institute, Inc. ii Published by Health Physics Society 1313 Dolley Madison Blvd. Suite 402 McLean, VA 2210
2、1 Copyright _ 2000 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 N13.52-1999 iii Table o
3、f contents Foreword.v 1 Introduction1 2 Purpose1 3 Scope.1 4 Definitions1 4.1 Special Word Usage1 4.2 Specific Terms.1 5 Dosimetry System Selection2 5.1 Sensitivity.2 5.2 Dosimeter Testing.2 5.3 Environmental Factors . 3 6 Use Factors3 6.1 Dosimeter Placement 3 6.2 Special Considerations3 7 Dosimetr
4、y System Calibration 4 7.1 Calibration Spectra . 4 7.2 Exposure Geometry 4 7.3 Neutron Quality Factor 4 8 References. 5 Annex A1 Introduction. 6 A2. Dosimetry Errors. 6 A2.1 Introduction 6 A2.2 Operational Errors . 6 A2.3 Detector Deficiencies. 6 A2.4 Geometric Uncertainties 6 A3. Dosimetry System C
5、alibration 7 A3.1 Introduction 7 A3.2 Reference Calibration 7 A3.3 Field Calibration. 7 A3.3.1 The Direct Method. 7 A3.3.2 Correction Factor Method 7 A3.4 Fluence-to-Dose Equivalent Factors7 A4. Dosimetry Systems10 A4.1 Introduction.10 A4.2 Nuclear Track Emulsions (NTA Film).10 A4.3 Albedo Dosimeter
6、s. 10 iv A4.4 Fission Track Dosimeters.10 A4.5 Superheated Drop Detectors.11 A4.6 Proton Recoil Detectors.11 A4.7 Combination Dosimeters11 References.13 Tables Table 1.9 v Foreword (This foreword is not part of American National Standard HPS N13.52-1999.) This standard provides guidance for routine
7、personnel neutron dosimetry. It applies to devices worn by individuals, as contrasted with hand-held or fixed-area instrumentation. It does not apply to dosimetry necessary for extremity monitoring or for criticality accidents. An appendix to this standard broadly summarizes the nature of errors and
8、 uncertainties associated with neutron personnel monitoring, calibration methodologies, and the c haracteristics of neutron dosimeters that are in common use. T he standard is designed to complement the American National Standard for Dosimetry, Personnel Dosimetry Performance (ANSI N13.11). This rev
9、ision of ANSI N319-1976 updates information from the earlier version concerning selection and calibration of personnel neutron dosimetry systems for work environments containn neutron radiation ranging in energy from thermal to less than 20 MeV. The guidance in this standard applies to dosimetry wor
10、n by individuals, as contrasted with hand-held or fixed-area instrumentation. This standard complements guidance contained in ANSI/HPS N13.11 r egarding performance testing criteria for personnel dosimeters. vi The Health Physics Society Working Group responsible for the original development of this
11、 standard had the following members: Eric E. Kearsley, Chairperson (National Council on Radiation Protection and Measurements, U.S.A.) Linda Bray (Edison International, U.S.A.) Richard V. Griffith (International Atomic Energy Agency, Vienna) Virendra Gupta (EG also commonly called the dosimeter HFKD
12、QJHSHULRGDosimetry system The dosimeters, the related data collection and processing instruments, and techniques required to evaluate the neutron dose equivalent received by exposed individuals. Effective dose The sum of the tissue-weighted dose equivalents to specific organs of the body specified b
13、y the appropriate authoritative body. Gray The special name for the unit of dose. One gray equals one joule per kilogram. Personal dose equivalent The dose equivalent in soft tissue below a specified point on the body at a specified depth. The depth is conventionally chosen to be one centimeter. Per
14、sonal neutron dosimeter (or dosimeter) One or more devices worn on the body for measuring the personal neutron dose equivalent. Quality factor A dimensionless factor selected to account for the differences in the biological effectiveness of different types of radiation in producing stochastic effect
15、s in human beings over the range of doses of concern for radiation-protection activities. Sievert The special name for the unit of dose equivalent. The dose equivalent in sieverts is numerically equal to the absorbed dose in grays multiplied by the quality factor. 5 Dosimetry System Selection A neut
16、ron dosimetry system shall be considered appropriate for use provided that a relationship can be established between the personal dose equivalent and the response of the dosimeter in the neutronradiation environment in which it is used. Insome cases this relationship varies widely depending on the n
17、eutron energy, angle of incidence and other factors. 5.1 Sensitivity The dosimetry system shall have a lower limit of detection (LLD) of 0.5 mSv personal dose equivalent or 5.0 mSv divided by the number of dosimetry periods per year, whichever is greater. For the purpose of this standard, the lower
18、limit of detection is considered to be that value of neutron individual dose equivalent for which there is a 95% confidence that the exposure will be detected and reported as a positive result. The procedure for calculation of the lower limit of detection is specified in ANSI/HPS N13.11 HPSSC/ANSI N
19、13.11 1993. 5.2 Dosimeter Testing The dosimeter shall be tested following the procedures of the neutron/gamma category of ANSI/HPS N13.11 HPSSC/ANSI N13.11 1993 with the following exceptions: (a) The neutron source used to perform test exposures specified in 5.3 should have a neutron energy spectrum
20、 representative of the field in which the dosimeter is to be used. However any neutron source and/or exposure geometry may be used to impart a neutron signal on the dosimeter; (b) One third of the dosimeters shall be irradiated at the beginning of a period of time that corresponds with a normal issu
21、e period, one third in the middle of this period, and one third at the end of this period; (c) The test shall be conducted using randomly selected exposure levels (as specified in N13.11) but with no exposure less than the lower limit of detection specified above. ANSI/HPS N13.52 - 1999 3 5.3 Enviro
22、nmental Factors The dosimeter shall meet the requirements of 5.1 and 5.2 when subjected to the following environmental factors after exposure to the test spectrum (each of these environmental tests may be performed separately): (1) Temperature extremes of 0 C and 45 C for 1 week or the duration of t
23、he dosimetry period, whichever is less; (2) A relative humidity of 90% at a temperature of at least 23 C for 1 week. or the duration of the dosimetry period whichever is less; (3) Normal intensity of artificial light or sunlight for the duration of the dosimetry period; (4) A drop to a hard surface
24、from a height of 2.0 meters. Beyond these considerations, other factors relating to either the unique characteristics of the dosimeter being considered or the specific requirements of the monitoring program should be evaluated. A review of the characteristics of several neutron dosimeters is provide
25、d in the Appendix to this standard. 6 Use Factors Use factors refer to those factors involved in the issue and wearing of personnel dosimeters that influence the accuracy, sensitivity, or precision of the neutron dosimetry system. These factors shall be identified and controlled by personnel respons
26、ible for the management of the radiation protection program. 6.1 Dosimeter Placement The normal placement of the dosimeter is determined by identifying the location(s) on the body at which a measurement of the personal dose equivalent will most nearly correlate with the effective dose equivalent con
27、sidering the expected geometry of the exposure. The normal placement of the dosimeter is determined by identifying the location(s) on the body at which a measurement of the personal dose equivalent will most nearly correlate with the effective dose considering the expected geometry of the exposure.
28、Tables of personal dose equivalent per unit of neutron fluence in slab geometry and values of effective dose per unit neutron fluence for a range of neutron energies and exposure geometries are available as a result of a joint effort by ICRU ICRU 1998 and ICRP ICRP 1996 (1997). Additional guidance o
29、n dosimeter placement is provided in HPS N13.41-1997 HPSSC/ANSI N13.41 1997. 6.2 Special Considerations The unique characteristics of each dosimetry system and the fields in which the dosimeter is exposed shall determine how the dosimeter is worn. Dosimeters that depend, for example, on an albedo ef
30、fect and which must be worn close to the body and shall not be suspended loosely from a chain hung around the neck. ANSI/HPS N13.52 - 1999 4 7 Dosimetry System Calibration 7.1 Calibration Spectra The neutron field used to calibrate the dosimeter shall be traceable to a reference laboratory standard.
31、 The neutron energy spectrum used for calibration should simulate as much as possible the spectrum expected in the area in which the dosimeter is to be used. The simulated spectrum should include not only the uncollided source spectrum, but also the contribution from neutrons scattered from walls an
32、d other structural materials. For radiation monitoring purposes, moderation and scattering by means of shielding materials, as well as the walls and floor of the calibration room itself may be used to achieve spectral simulation. For cases in which it is either not practical or not possible to achie
33、ve adequate spectral simulation, the relationship between spectra encountered in the work place and the primary calibration spectrum shall be established to ensure that the dosimeters neutron response reflects the correct neutron personal dose equivalent in these environments. Specific calibration t
34、echniques are discussed in the Appendix to this standard. 7.2 Exposure Geometry The geometry of exposure to the dosimeter in the work environment should be considered during calibration. The accuracy of many personnel neutron dosimeter systems is strongly dependent on the geometry of exposure, in pa
35、rticular the angle of exposure and the proximity and composition of surrounding material. As much as possible, dosimeter calibration should simulate the actual conditions of dosimeter use to ensure accurate dose measurement. A phantom such as that specified by HPSSC/ANSI (1993) should be used during
36、 the calibration of the dosimetry system. The phantom should simulate the neutron scattering and absorption properties of the human body in the configuration in which the dosimeter is expected to be used. 7.3 Neutron Quality Factor There is no consensus at this time on the appropriate choice for the
37、 value of the quality factor to be used for neutrons. A variety of factors have been recommended by national, international, and regulatory bodies. These factors vary due to differences in the choice of phantom geometry, depth at which the dose equivalent is to be determined, and the assessment of t
38、he relative risk of neutrons to photons. This standard ANSI/HPS N13.52 - 1999 5 does not adopt or preclude the use of any of the conventions listed above. A specific recommendation and more discussions are provided in the appendix to this standard. 8 References HPSSC/ANSI N13.11 1993 American Nation
39、al Standard for Dosimetry Personnel Dosimetry Performance: Criteria for Testing. This standard was most recently issued in 1993 (ANSI N13.11 - 1993) and is currently being revised (ANSI/HPS N13.11-2000). Health Physics Society, McLean, VA. ANSI/HPS HPSSC/ANSI N13.41-1997. An Amercian national Standa
40、rd, Criteria for Performing Multiple Dosimetry. Health Physics Society, McLean, VA. International Commission on Radiation Units and Measurements Report No. 57, Conversion Coefficients for Use in Radiological Protection Against External Radiation, 1998, Bethesda, Maryland. International Commission on
41、 Radiological Protection Publication No. 74, Conversion Coefficients for use in Radiological Protection against External Radiation, Annals of the ICRP Volume 26 No. 3/4 1996, Pergamon, Elsevier Science Inc., Tarrytown, New York. ANSI/HPS N13.52 - 1999 6 APPENDIX A (This Appendix is not a part of Ame
42、rican National Standard for Personnel Neutron Dosimeters (Neutron Energies Less than 20 MeV), N13.52-1999, but is included for information purposes only.) Dosimetry Problems and Capabilities A1 Introduction The Appendix has been included to indicate some of the problems and considerations involved i
43、n the selection and calibration of dosimeters to be used as part of a neutron dosimetry program. The user will need to make the detailed decisions necessary for the dosimetry program after careful analysis of data provided in the literature and through discussions with others involved in dosimetry p
44、rogram development. There are a number of excellent review papers on personnel neutron dosimetry Griffith 1979; Ing 1985; Gibson 1988; DOE 1983; Eisenhauer NUREG/CR 3400. The proceedings of meetings on neutron dosimetry are sources of information on the current status of neutron dosimetry programs a
45、t a number of laboratories Burger 1981; Schraube 1985; Schraube 1988. The Department of Energy has supported many workshops and symposia on personnel dosimetry DOE 1981; DOE 1982; DOE 1983; Neutron Dosimetry 1997. A2. Dosimetry Errors A2.1 Introduction There are a number of uncertainties and detecto
46、r deficiencies that contribute potential sources of error in the assessment of the dose equivalent from neutron dosimeter data. It is important to be aware of these sources so that they can be avoided, or when unavoidable, controlled as much as possible. A2.2 Operational Errors Errors such as equipm
47、ent malfunction and personnel errors can be minimized by establishing detailed written procedures that describe the step-by-step techniques that can be expected to yield reproducible results. A2.3 Detector Deficiencies Physical errors attributed to the detector can include such things as photon inte
48、rference, loss of information due to fading, temperature or other ambient stresses, incorrect spectral response or total lack of response in specific portions of the spectrum, and poor reproducibility. In situations where there is significant spectral variadtion from one radiation area to another, i
49、t is important that individual consideration be given to each area. This may require that separate calibration factors be used for different radiation areas. A2.4 Geometric Uncertainties Geometric errors occur because of source size, source distribution, and variations in source to dosimeter distances. Orientation introduces large errors when a single dosimeter is attached at 7 one position on the body; yet it is impractical to cover the individual with dosimeters to measure orientation and vertical and horizontal distributions. Field survey meas
