1、 American National Standard ANSI/HPS N43.14-2011 Radiation Safety for Active Interrogation Systems for Security Screening of Cargo, Energies up to 100 MeV Approved: August 4, 2011 American National Standards Institute, Inc. ii Published by Health Physics Society 1313 Dolley Madison Blvd. Suite 402 M
2、cLean, VA 22101 Copyright 2011 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 N43.14-201
3、1 iii The Accredited Standards Committee N43, on Equipment for Non-Medical Radiation Applications, had the following membership at the time it processed and approved this standard (April 15, 2011): Chairperson William Morris Vice-chairperson Scott O. Schwahn ABB Industrial Systems, Inc. John R. Duke
4、s American Conference of Government Industrial Hygienists Gordon Lodde American Iron and Steel Institute Anthony LaMastra American Society for Testing and Materials Marvin M. Turkanis Canadian Nuclear Safety Commission Slobodan Jovanovic Health Physics Society Sander Perle Los Alamos National Labora
5、tory Scott Walker National Council on Radiation Protection and Measurement Susan M. Langhorst National Institute of Standards and Technology James S. Clark Underwriters Laboratories, Inc. Peter Boden U.S. Department of the Air Force, Office of the Surgeon General Ramchandra Bhat U.S. Department of t
6、he Army, Office of the Surgeon General Frances Szrom U.S. Department of the Army Gregory R. Komp U.S. Department of Energy Peter OConnell U.S. Department Health, Education, and Welfare, Public Health Service Daniel F. Kassiday U.S. Department of Homeland Security Siraj M. Khan U.S. Department of the
7、 Navy Brendon K. Glennon U.S. Nuclear Regulatory Commission John P. Jankovich Individual members: Susan J. Engelhardt David W. Lee iv The ANSI/HPS N43.14 Standards Subcommittee responsible for writing had the following members: Siraj M. Khan, Chair (U.S. Department of Homeland Security) David M. Gil
8、liam, Co-chair (National Institute of Standards and Technology) Thomas M. Cuff (Parsons, Inc. / Domestic Nuclear Detection Office) James L. Jones (Idaho National Laboratory) George Vourvopoulos (Science Applications International Corporation) Richard C. Lanza (Massachusetts Institute of Technology)
9、Brad J. Micklich (Argonne National Laboratory) Laurie S. Waters (Los Alamos National Laboratory) Peter Ryge (Consultant, formerly Rapiscan Systems) v Contents Abstract ix Preface . x 1.0 Scope . 1 2.0 Applicable Documents (Normative References) 1 2.1 Federal and State Regulations 1 2.2 Related ANSI
10、Standards . 1 3.0 Definitions of Terms . 1 4.0 Modalities of Systems and Types of Installations . 5 4.1 Modalities of Active Interrogation Systems 5 4.2 Types of Installations Containing Active Interrogation Systems . 6 5.0 Administrative Controls . 6 5.1 Radiation Safety Program Plan . 6 5.2 Radiat
11、ion Safety Committee 6 5.3 Radiation Safety Training . 7 5.4 Monitoring of Radiation Exposure 7 5.5 Warning Signs for Access Control . 7 5.5.1 “Closed” Installations 7 5.5.2 “Open” Installations . 7 5.5.3 “Hybrid” Installations . 8 5.6 Barriers for Access Control 8 6.0 Engineered Controls 8 6.1 Cont
12、rols and Interlocks 9 6.1.1 System Control . 9 6.1.2 Facility (Installation) Interlocks 9 6.1.3 System Interlocks 9 6.1.4 Emergency Shutdown Switches (Scrams) 9 6.2 Warning Devices . 9 6.3 Shielding 10 6.3.1 “Closed” Installation 10 6.3.2 “Open” Installation . 10 6.3.3 “Hybrid” Installation . 10 6.3
13、.4 Additional Shielding Devices . 10 6.4 Signage and Barriers . 10 6.5 Radiation Monitoring Equipment 10 6.6 Additional Controls . 10 7.0 Radiation Safety in System Operation 11 7.1 Exposure to Stowaways . 11 7.1.1 Pre-screening of Trucks and Cargo Containers 11 7.1.2 Verification of Probability of
14、Detection for Human Occupancy 11 7.2 “Closed” Installations . 11 7.2.1 Shielding . 11 7.2.2 Radiation Safety Surveys 11 7.3 “Open” Installations 11 7.3.1 Radiation Safety Surveys 11 vi 7.3.2 Determination of Radiation Safety Exclusion Zone . 12 7.3.3 Radiation Source Safety . 12 7.3.4 Leakage Test f
15、or Sealed Sources . 12 7.3.5 Accidental or Deliberate Explosion . 12 7.3.6 Major Fire 12 7.3.7 Secure Storage of Sealed Sources . 12 7.3.8 Radiation Safety Controls . 12 7.3.9 Control of Exclusion Zone (Controlled Area) . 12 7.3.10 Klystrons and Magnetrons 12 7.4 Skyshine 13 7.5 Induced Radioactivit
16、y . 13 7.5.1 Radiation Survey to Monitor Activation Products 13 7.5.2 Storage and Disposal of Activation Products 13 7.6 Environmental Assessment (EA) or Environmental Impact Statement (EIS). 13 Annex A Administrative Controls 14 A.1 Radiation Safety Program Plan. 14 A.2 Stop Work Authority 15 A.3 T
17、raining and Qualifications of Personnel 16 A.4 Radiation Exposure Control 17 A.5 ALARA Program . 19 A.6 Instrumentation and Surveillance 20 A.7 Radiation Areas and Postings (Signs) 21 A.8 Control of Radiological Work Annex B Radiation Protection for a “Closed” Installation . 23 B.1 Shielding from Br
18、emsstrahlung (Photons) 23 B.2 Primary Shielding 23 B.3 Secondary Shielding . 30 B.4 Shielding from Photoneutrons. 32 B.5 Joints and Ducts . 33 B.6 Dose to Stowaway 33 B.7 Photon and Neutron Skyshine 35 Annex C Radiation Protection for an “Open” Installation 36 C.1 Use of Shielding and Distance to Pr
19、ovide Radiation Protection . 36 C.2 Example of a Portal System Using a 6-MeV LINAC . 41 C.3 Example of a Portal System Using 14-MeV Neutrons 44 C.4 Procedure for Radiation Safety Measurements 45 Annex D Special Dose Rate Measurement Instrumentation 50 D.1 Choice of Monitoring Equipment. 50 D.2 Corre
20、ction for Dead Time from Pulsed Radiation . 51 D.3 Correction for High Energy . 52 D.4 Correction for High Intensity . 52 D.5 Correction for Beam Size for In-beam Measurements 52 Annex E Radiation Transport Code Simulations for Radiation Safety . 53 E.1 Computer Codes for Shielding Calculations . 53
21、 E.2 Introduction to MCNP and MCNPX . 53 E.3 Examples of MCNPX Calculations for LINACs . 59 E.4 Neutron Shielding and Distribution Calculations . 59 vii Annex F Induced Radioactivity 64 F.1 Activity Induced by Photons 64 F.2 Activation by Neutrons Produced in the (, n) Reaction 66 F.3 Activation by
22、Fast Neutrons Produced in a Neutron Generator 66 F.4 Neutron Activation Calculator (WISE) . 67 Annex G Bibliography (Informative References) 70 Tables Table 1. Maximum permissible dose (MPD) values. 8 Table A1. Summary of dose limits for occupationally and non-occupationally exposed adults and minor
23、s. 18 Table A2. Summary of posting requirements. 20 Table B1. Suggested occupancy factors. 24 Table B2. Primary-barrier TVLs for ordinary concrete ( = 2.35 g cm3), steel ( = 7.87 g cm3), and lead ( = 11.35 g cm3) for LINAC end-point energies from 4 to 30 MeV and 60Co gamma rays. . 28 Table B3. Tenth
24、-value layers (TVLs) for leakage radiation in ordinary concrete. 31 Table B4. Albedo, , at 1 m from a human phantom, target-to-phantom distance of 1 m, and field size of 400 cm2. 32 Table B5. Tenth-value layers (TVLs, in cm) from human phantom scattered radiation at various scatter angles. . 32 Tabl
25、e B6. Fast neutron fluence, , at 1 m from the target (in cm2Gy1). 35 Table B7. Fast neutron equivalent dose, Hn, at 1 m from target (in Sv Gy1). 35 Table C1. Measured and calculated dose rates along the source-detector line for a 37-GBq (1-Ci) 137Cs source (redacted from Table 1 of the 1996 report R
26、ef. C1, Annex G). . 39 Table C2. Radiation field data from the 37-GBq (1-Ci) 137Cs source (shutter open). . 40 Table D1. Required equipment for personnel and area monitoring. 50 Table E1. Isotopic composition of elements used in simulations. 56 Table E2. Elemental composition of materials used in si
27、mulations. 57 Table F1. Degree of susceptibility of common materials to activation in high-energy photon beams. 64 Table F2. Radionuclide production in (, n) reaction. . 65 viii Table F3. Isotopes that contribute to accelerator radioactivity by thermal neutron activation. 67 Table F4. Activities of
28、various nuclides produced in 1 kg of concrete subjected to a neutron flux of 100.00 106cm2s1and irradiation and delay times of 1 and 0 h, respectively. . 68 Table F5. Activities of various nuclides produced in 1 kg of type 304 stainless steel subjected to a neutron flux of 100.00 106cm2s1, and irrad
29、iation and delay times of 1 and 0 h, respectively. 68 Figures Figure B1. Conceptual drawing of a “closed” installation containing a gantry system. . 25 Figure B2. Tenth-value layers (TVLs, in units of g cm2) in ordinary concrete, iron (steel), and lead, for thick-target bremsstrahlung under broad-be
30、am conditions at zero degrees incidence, as a function of the energy E0of electrons incident on high-Z target. . 26 Figure B3. Transmission factors for thick-target bremsstrahlung under broad-beam conditions as a function of shielding thickness for the common shielding materials concrete ( = 2.35 g
31、cm3), steel (iron) ( =7.8 g cm3), and lead ( = 11.35 g cm3), for various end-point energies. . 27 Figure C1. Dose rates normal to the source-detector line. 38 Figure C2. A conceptual drawing of an “open” portal system for active interrogation using high-energy photons. 41 Figure C3. A conceptual dra
32、wing of an “open” portal system for active interrogation using fast neutrons. 44 Figure D1. Pulses from a linear accelerator (LINAC). 51 Figure E1. An example of an MCNP history. . 54 Figure E2. Bremsstrahlung spectrum generated by 9-MeV electrons in a 0.5-cm-thick tungsten spherical shell. . 60 Fig
33、ure E3. The x-ray fluence as a function of distance for a 9-MeV LINAC. 61 Figure E4. Flux mesh tally viewed from the top of the slit, that is, the length of the slit is perpendicular to the plane of the drawing. . 62 Figure E5. Geometry plot showing the results of 14-MeV neutron generator shielding
34、calculations. . 63 ix Radiation Safety for Active Interrogation Systems for Security Screening of Cargo, Energies up to 100 MeV Abstract (This abstract is not part of the American National Standard ANSI/HPS N43.14.) This standard establishes radiation safety policies and procedures for the safe use
35、of active interrogation systems in applications involving the detection of weapons of mass destruction (WMD) and other contraband in trucks and cargo containers. The intent and purpose of this standard is to ensure that the workers and members of the general public (including stowaways) are protecte
36、d from excessive exposure to ionizing radiation (such as high-energy photons, neutrons, and charged particles) and that the radiation exposures to these individuals are maintained well within the regulatory limits as established by Nuclear Regulatory Commission (NRC), Occupational Safety and Health
37、Administration (OSHA), and other federal and state regulatory agencies. This document also contains a number of annexes that provide useful information and guidance in implementing this standard. Key words: active interrogation, bremsstrahlung, fast neutrons, gamma rays, health physics, high-energy
38、photons, induced radioactivity, linear accelerator (LINAC), national standard, neutron activation, radiation generating device (RGD), radiation safety, sealed radioactive sources, sealed tube neutron generator (STNG), weapons of mass destruction (WMD), x-rays. x Preface (This preface is not part of
39、the American National Standard ANSI/HPS N43.14.) Increased vigilance in the area of homeland security requires that cargo containers entering the USA be screened for the detection of weapons of mass destruction (WMD) and other contraband such as chemical warfare agents, drugs, and explosives. Althou
40、gh security imaging systems using x-rays and gamma rays have been deployed at U.S. ports of entry, there is a need to develop and deploy active interrogation systems to augment and enhance the process of interdiction of dangerous cargo. Active interrogation systems depend on the interaction of the i
41、ncident radiation, either neutrons or high-energy photons, with the nuclei of the object under interrogation. Nuclear reactions such as inelastic scattering (n, n), thermal neutron capture (n, ), photonuclear reactions (photo-fission , xn, or fast neutron induced fission) are good examples of such r
42、eactions and yield information that can be used to “identify” the material. Another example is nuclear resonance fluorescence (NRF), in which the nuclear levels of the target nuclei are excited by incident photons with the resultant emission of characteristic fluorescence gamma rays, which are detec
43、ted by appropriate detectors. In all these systems the object under interrogation is “actively” participating in the physical processes taking place in the system. On the other hand, in a security imaging system using x-rays and gamma rays, the parts of the object being inspected are blocking differ
44、ent amounts of the incident radiation, thereby forming an image at the detector. This is the basis for “anomaly” detectors, which can give information about the size, shape, density, and location of the object of interest inside the container. Commercial examples of such techniques currently in use
45、employ radiation sources such as radioisotopes, x-ray tubes, or bremsstrahlung from electron accelerators. An ANSI standard, N42.41, entitled “Minimum Performance Criteria for Active Interrogation Systems Used for Homeland Security,” 2007, has been published by the IEEE Secretariat. The ANSI N42.41
46、standard deals primarily with the performance standards of active interrogation systems. This standard, ANSI N43.14, focuses on the establishment of radiation safety policies and procedures for the safe operation of the active interrogation systems. There are gaps in federal and state regulations re
47、garding the safe operation of accelerator systems and x-ray sources. NRC regulations apply only to radioactive byproduct use, whereas FDA regulations for devices producing radiation apply only to manufacturing and maintenance, but not to the operation of the devices. Active interrogation systems may
48、 employ byproduct materials, accelerators, x-ray generators, and combinations of these radiation sources for the production of the interrogating radiation. This standard specifies radiation safety policies and procedures for the operation of all of these diverse radiation sources by drawing on the m
49、ost applicable existing NRC, FDA, and OSHA regulations and NCRP recommendations, without regard to regulatory boundary limits and extending the applicable standards to bridge the existing gaps. Part A of this standard contains the following sections: Scope (Sec. 1.0), Applicable Documents (Normative References) (Sec. 2.0), Definitions of Terms (Sec. 3.0), Modalities of Systems and Types of Installations (Sec. 4.0),
