American National Standard Performance Criteria for Spectroscopy- Based Portal Monitors Used for Homeland Security

Transcription

1 American National Standard Performance Criteria for Spectroscopy- Based Portal Monitors Used for Homeland Security Accredited by the American National Standards Institute Sponsored by the National Committee on Radiation Instrumentation, N42 I E E E 3 Park Avenue New York, NY , USA ANSI N January 2007

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3 American National Standard Performance Criteria for Spectroscopy- Based Portal Monitors Used for Homeland Security Sponsor National Committee on Radiation Instrumentation, N42 Accredited by the American National Standards Institute Secretariat Institute of Electrical and Electronics Engineers, Inc. Approved 28 August 2006 American National Standards Institute

4 Abstract: The performance requirements for radionuclide identifying portal monitors, also referred to as spectroscopic portal monitors, are described in this standard. The requirements stated are based on monitors used in support of efforts associated with the U.S. Department of Homeland Security. Keywords: gamma spectroscopy, homeland security, instrument test, portal monitors, radiation detectors, radionuclide identification The Institute of Electrical and Electronics Engineers, Inc. 3 Park Avenue, New York, NY , USA Copyright 2007 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Published 22 January Printed in the United States of America. IEEE is a registered trademark in the U.S. Patent & Trademark Office, owned by the Institute of Electrical and Electronics Engineers, Incorporated. Print: ISBN SH95598 PDF: ISBN SS95598 No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher.

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6 American National Standard An American National Standard implies a consensus of those substantially concerned with its scope and provisions. An American National Standard is intended as a guide to aid the manufacturer, the consumer, and the general public. The existence of an American National Standard does not in any respect preclude anyone, whether he has approved the standard or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standard. American National Standards are subject to periodic reviews and users are cautioned to obtain the latest editions. CAUTION NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Institute require that action be taken to affirm, revise, or withdraw this standard no later than five years from the date of publication. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute. Authorization to photocopy portions of any individual standard for internal or personal use is granted by the Institute of Electrical and Electronics Engineers, Inc., provided that the appropriate fee is paid to Copyright Clearance Center. To arrange for payment of licensing fee, please contact Copyright Clearance Center, Customer Service, 222 Rosewood Drive, Danvers, MA USA; Permission to photocopy portions of any individual standard for educational classroom use can also be obtained through the Copyright Clearance Center.

7 Introduction This introduction is not part of ANSI N , American National Standard Performance Criteria for Spectroscopy-Based Portal Monitors Used for Homeland Security. This standard is the responsibility of the Accredited American Standards Committee on Radiation Instrumentation, N42. The standard was approved by the N42 letter ballot of July August Notice to users Errata Errata, if any, for this and all other standards can be accessed at the following URL: standards.ieee.org/reading/ieee/updates/errata/index.html. Users are encouraged to check this URL for errata periodically. Interpretations Current interpretations can be accessed at the following URL: index.html. Patents Attention is called to the possibility that implementation of this standard may require use of subject matter covered by patent rights. By publication of this standard, no position is taken with respect to the existence or validity of any patent rights in connection therewith. The IEEE shall not be responsible for identifying patents or patent applications for which a license may be required to implement an IEEE standard or for conducting inquiries into the legal validity or scope of those patents that are brought to its attention. v

8 Participants At the time it approved this standard, the Accredited Standards Committee on Radiation Instrumentation, N42, had the following membership: Michael P. Unterweger, Chair Morgan Cox, Deputy Chair William Ash, Administrative Secretary Organization Represented...Name of Representative Bartlett Services.... Morgan Cox Canberra Markku Koskelo Chew, M.H.....Jack M. Selby Commerce Dept, U.S. NIST.....Michael Unterweger...Louis Costrell (Alt.) Consultant...Frank X. Masse Department of Homeland Security...Peter Shebell Entergy-ANO.....Ron Schwartz Health Physics Society..Sandy Perle IEEE...Louis Costrell...Julian Forster (Alt.)...Anthony Spurgin (Alt.)...Michael Unterweger (Alt.) International Medcom.. Don Sythe Lawrence Berkeley National Lab. Edward J. Lampo Lawrence Livermore National Lab.....Gary Johnson NASA, GSFC...Sachidananda R. Babu Nuclear Regulatory Commission....Cynthia Jones Nuclear Stds Unlimited.. Al N. Tschaeche ORNL.. Peter J. Chiaro, Jr......Charles Britton (Alt.) ORTEC....Ronald M. Keyser Pacific NW Labs.....Richard Kouzes Swinth Associates...Kenneth L. Swinth U.S. Army.. Edward Groeber Members-At-Large....Ernesto Corte...Joseph C. McDonald...Paul L. Phelps..Joseph Stencel.. Lee J. Wagner vi

9 At the time this standard was approved, Subcommittee N42.HSI had the following membership: Michael P. Unterweger, Co-Chair Morgan Cox, Co-Chair Paul Bailey Peter J. Chiaro, Jr. David Gilliam Mark Hoover Cynthia G. Jones Ronald Keyser Richard Kouzes Joseph C. McDonald Leticia Pibida Brain Rees Peter Shebell David Trombino At the time this standard was approved, the ANSI Working Group had the following members: Peter J. Chiaro, Jr., Chair and Project Leader Carl Czajkowski Chuck Finfrock Jens Hovgaard Adam Hutter Cynthia Jones Ron Keyser Dick Kouzes George Lasche Dean Mitchell Richard Oxford Leticia Pibida Alan Proctor Brian Rees Dave Trombino Michael P. Unterweger vii

10 Contents 1. Overview Scope Purpose General Normative references Definitions General definitions Definitions of particular relevance to ANSI N General considerations Standard test conditions Units and uncertainties Special word usage Design requirements General characteristics Physical configuration Spectral identification Indication features Occupancy and speed sensors for vehicle monitors Markings Power supply Battery life-time Protection of switches Effective range of measurement Software and data analysis Radiation detection and indication performance requirements Reference gamma-ray radiation False alarms Response to gamma radiation Response to neutron radiation Over-range Neutron indication in the presence of photons Background effects Radionuclide identification Determination of full-energy-peak efficiency Determination of full width-half maximum (FWHM) viii

11 7. Environmental performance requirements Ambient temperature Relative humidity Moisture and dust protection Electromagnetic performance requirements Electrostatic discharge (ESD) Radio frequency (RF) susceptibility Radiated emissions Conducted disturbances induced by bursts and radio frequencies Magnetic fields Surges and oscillatory waves Mechanical performance requirements Vibration Microphonics/impact Documentation Type test report Report Operation and maintenance manual Annex A (informative) Bibliography A.1 General A.2 Detectors A.3 Detection and identification instruments A.4 Radiological protection instruments A.5 EMC A.6 Units, quantities, and calibrations A.7 Security monitors Annex B (informative) Diagram of mounting dimensions for radionuclide identifying portal monitors ix

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13 American National Standard Performance Criteria for Spectroscopy- Based Portal Monitors Used for Homeland Security 1. Overview 1.1 Scope This standard specifies the operational and performance requirements for spectroscopy-based portal monitors used in U.S. Homeland Security applications. Spectroscopy-based portal monitors have the ability to detect radioactivity and identify radionuclides that may be present in or on persons, vehicles, or containers through the use of gamma spectroscopy techniques. Performance requirements for those portal monitors that do not provide information about the specific radionuclide present are addressed by ANSI N Operational requirements established by this standard include radiation detection and radionuclide identification, and those requirements associated with the expected electrical, mechanical, and environmental conditions when a monitor is deployed. The test methods described in this standard provide a means to ensure that a monitor meets the requirements stated. Successful completion of the tests described in this standard should not be construed as an ability to successfully detect and identify all radionuclides in all environments. This standard does not address portal monitors that may have the ability to reduce the effects caused by the presence of naturally occurring radioactive material (NORM) without the ability to identify specific radionuclides (see ANSI N42.35) Purpose The purpose of this standard is to specify the performance criteria and test methods for spectroscopy-based portal monitors used for Homeland Security. 1 The ANSI N42 publications included in this clause are available from the Institute of Electrical and Electronics Engineers, 445 Hoes Lane, Piscataway, NJ , USA ( 1

14 1.3 General Evaluation of monitors Testing is conducted under a set of conditions to determine if a monitor meets the requirements of this standard. Special applications, which could include a monitor s operation under weather conditions not addressed by this standard, shall require additional testing. Detection needs not addressed by this standard shall also require additional testing. Evaluations provide information to government agencies and other users on the capability of radionuclideidentifying portal monitors for reliably detecting and identifying radioactive material Meeting performance specifications Obtaining operating performance that meets or exceeds the specifications stated in this standard depends upon properly installing the monitor, establishing appropriate operating parameters, providing security for the systems, maintaining calibration, implementing a suitable routine testing and maintenance program, auditing compliance with quality requirements, and providing proper training for operating personnel. 2. Normative references This standard shall be used in conjunction with the following publications. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments or corrigenda) applies. ANSI N42.22, American National Standard Traceability of Radioactive Sources to the National Institute of Standards and Technology (NIST) and Associated Instrument Quality Control. 2 ANSI N42.23, American National Standard Measurement and Associated Quality Assurance for Radioassay Laboratories. ANSI N42.34, American National Standard Performance Criteria for Hand-Held Instruments for the Detection and Identification of Radionuclides. ANSI N42.35, American National Standard for Evaluation and Performance of Radiation Detection Portal Monitors for Use in Homeland Security. ANSI N42.42, American National Standard Data Format Standard for Radiation Detectors Used for Homeland Security. 3 ANSI/TIA-232-F-1997, Interface Between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange. ANSI/TIA/EIA-485-A-98, Electrical Characteristics of Generators and Receivers for Use in Balanced Digital Multipoint Systems. FCC Rules, Code of Federal Regulations, Title 47, Part 15, Radio Frequency Devices. 4 2 The ANSI N42 publications included in this clause are available from the Institute of Electrical and Electronics Engineers, 445 Hoes Lane, Piscataway, NJ , USA ( 3 The ANSI N42.42 schema can be obtained from 4 CFR publications are available from the Superintendent of Documents, U.S. Government Printing Office, P.O. Box 37082, Washington, DC , USA ( 2

15 IAEA Safety Guide No. RS-G-1.9, Categorization of Radioactive Sources. 5 IEC {Ed.2.0}, International Electrotechnical Vocabulary Part 393: Nuclear instrumentation: Physical phenomena and basic concepts. 6 IEC , {Ed.2.0}, International Electrotechnical Vocabulary Chapter 394: Nuclear instrumentation: Instruments. IEC , Environmental Testing Part 1: General and Guidance. IEC , Environmental Testing Part 2-18: Tests Test R and Guidance: Water. IEC , Environmental Testing Part 2-75: Tests Test Eh: Hammer Tests. IEC 60529, Degrees of Protection Provided by Enclosures (IP Code), IP54. IEC , Classification of Environmental Conditions Part 4-4: Guidance for the Correlation and Transformation of Environmental Condition Classes of IEC to the Environmental Tests of IEC Stationary Use at Non-Weatherprotected Locations. IEC ,, Electromagnetic Compatibility (EMC) Part 4-1: Testing and Measurement Techniques Overview of IEC Series.. IEC , Electromagnetic Compatibility (EMC) Part 4-2: Testing and Measurement Techniques Electrostatic Discharge Immunity Test. IEC , Electromagnetic Compatibility (EMC) Part 4-3: Testing and Measurement Techniques Radiated, Radio-Frequency, Electromagnetic Field Immunity Test. IEC , Electromagnetic Compatibility (EMC) Part 4-4: Testing and Measurement Techniques Electrical Fast Transient/Burst Immunity Test. IEC , Electromagnetic Compatibility (EMC) Part 4-5: Testing and Measurement Techniques Surge Immunity Test. IEC , Electromagnetic Compatibility (EMC) Part 4-6: Testing and Measurement Techniques Immunity to Conducted Disturbances, Induced by Radio-Frequency Fields. IEC , Electromagnetic Compatibility (EMC) Part 4-12: Testing and Measurement Techniques Oscillatory Waves Immunity Test. IEC , Electromagnetic Compatibility (EMC) Part 4-14: Testing and Measurement Techniques Voltage Fluctuation Immunity Test. IEC , Electromagnetic Compatibility (EMC) Part 4-28: Testing and Measurement Techniques Variation of Power Frequency Immunity Test. IEC 61455, Nuclear Instrumentation MCA Histogram Data Interchange Format for Nuclear Spectroscopy. 5 IAEA publications are available from the International Atomic Energy Agency, P.O. Box 100, Wagner Strasse 5, A-1400 Vienna, Austria ( 6 IEC publications are available from the Sales Department of the International Electrotechnical Commission, Case Postale 131, 3 rue de Varembé, CH-1211, Genève 20, Switzerland/Suisse ( IEC publications are also available in the United States from the Sales Department, American National Standards Institute, 11 West 42nd Street, 13th Floor, New York, NY 10036, USA ( 3

16 ISO/IEC , X and Gamma Reference Radiation for Calibrating Dosemeters and Doserate Meters and for Determining the Response as a Function of Photon Energy Part 3: Calibration of Area and Personal Dosemeters and the Measurement of Their Response as a Function of Energy and Angle of Incidence. 7 Manual for Railway Engineering, American Railway Engineering and Maintenance-of-Way Association, Mira Digital Publishing, Inc., 2003, Figure , page NEMA 250, Enclosures for Electrical Equipment (1000 Volts Maximum) Definitions The following definitions apply to this standard, as well as to ANSI N42.32 [B11], 10 ANSI N42.33 [B12], ANSI N42.34 [B13], and ANSI N42.35, which have all been developed at the request of the U.S. Department of Homeland Security (DHS) for instruments to be used by DHS and emergency responders. 3.1 General definitions A-weighted sound level: The frequency weighting of an acoustic spectrum according to a standardized frequency response-curve based on the frequency response of the human ear acceptance test: Evaluation or measurement of performance characteristics to verify that certain stated specifications and contractual requirements are met accepted ambient photon background: The background exposure rate as measured using a highpressure ionization chamber, an energy compensated Geiger-Mueller (GM) tube, an energy compensated proportional counter, a tissue equivalent plastic scintillator, a scintillator with spectral compensation, or any other exposure rate instrument having a nearly constant energy response (±30% in the energy range from 60 kev to 1.5 MeV) accredited testing laboratory: Testing laboratory that has been accredited by an authoritative body with respect to its qualifications to perform verification tests on the type of instruments covered by this standard accuracy: The degree of agreement between the observed value with the conventionally true value of the quantity being measured adjust: To alter the reading of an instrument by means of a built-in variable (hardware or software) control alarm: An audible, visual, or other signal activated when the instrument reading or response exceeds a preset value or falls outside of a preset range calibrate: To adjust and/or determine the response or reading of a device relative to a series of conventionally true values. 7 ISO publications are available from the ISO Central Secretariat, Case Postale 56, 1 rue de Varembé, CH-1211, Genève 20, Switzerland/ Suisse ( ISO publications are also available in the United States from the Sales Department, American National Standards Institute, 11 West 42nd Street, 13th Floor, New York, NY 10036, USA ( 8 AREMA publications are available from AREMA, Derekwood Lane, Suite 210, Lanham, MD , USA ( 9 NEMA publications are available from Global Engineering Documents, 15 Inverness Way East, Englewood, CO 80112, USA ( 10 The numbers in brackets correspond to those of the bibliography in Annex A. 4

17 3.1.9 calibration: A set of operations under specified conditions that establishes the relationship between values indicated by a measuring instrument or measuring system and the conventionally true values of the quantity or variable being measured check source: A not-necessarily calibrated source that is used to confirm the continuing functionality of an instrument coefficient of variation (COV) (%): Ratio of the standard deviation, s, to the arithmetic mean, x, of a set of n measurements, x i, given by the following formula: 2 s 1 ( xi x) V = = x x n conventionally true value (CTV): The commonly accepted best estimate of the value of that quantity. NOTE This and the associated uncertainty will preferably be determined by a national or transfer standard, or by a reference instrument that has been calibrated against a national or transfer standard, or by a measurement quality assurance (MQA) interaction with the National Institute of Standards and Technology (NIST) or an accredited calibration laboratory. (See ANSI N42.22 and ANSI N42.23.) decade: A range of values for which the upper value is a power of ten above the lower value detection limits: The extremes of detection or quantification for the radiation of interest. NOTE The lower detection limit is the minimum statistically quantifiable instrument response or reading. The upper detection limit is the maximum level at which the instrument meets the required accuracy detector: A device or component designed to produce a quantifiable response to ionizing radiation normally measured electronically effective center: For a given set of irradiation conditions, the point within a detector where the response is equivalent to that which would be produced if the entire detector was located at the point effective range of measurement: Range of measurements within which the requirements of this standard are met energy dependence: Variation in instrument response as a function of radiation energy for a constant radiation type and exposure rate referenced to air exposure: The measure of ionization produced in air by x-ray or gamma-ray radiation. NOTE The special unit of exposure rate is the Roentgen per hour, abbreviated in this standard as R/h. NOTE In this standard, the International System (SI) units sievert (Sv) or gray (Gy) follow in parentheses the Roentgen value R, though the two units are not physically equivalent false alarm: Alarm NOT caused by a radioactive source under the specified background conditions. 11 Notes in text, tables, and figures of a standard are given for information only and do not contain requirements needed to implement this standard. 5

18 functional check: A frequently used qualitative check to determine that an instrument is operational and capable of performing its intended function. NOTE Such checks may include, for example, battery check, zero setting, or source response check indicated value: (A) A scale or decade reading. (B) The displayed value of the readout. See also: reading indication: Displayed signal from the instrument to the user conveying information such as scale or decade, status, malfunction or other critical information influence quantity: Quantity that may have a bearing on the result of a measurement without being the subject of the measurement innocent alarm: An alarm resulting from an actual increase in radiation level, but for reasons that are not due to the detection of illicit radioactive materials. NOTE Also known as nuisance alarm instrument: A complete system consisting of one or more assemblies designed to quantify one or more characteristics of ionizing radiation or radioactive material instrument hour: The number of operating instruments multiplied by the amount of time they are operating (e.g. 8 instruments operating for 3.75 h is equivalent to 30 instrument hours) interdiction: Stopping the illicit or inadvertent movement of radioactive material that has been discovered as a result of radiation detection or measurement monitoring: Means provided to continuously indicate the state or condition of a system or assembly. NOTE May also be used for the real time measurement of radioactivity or exposure rate overload response: See: over-range response over-range response: The response of an instrument when exposed to radiation intensities greater than the upper measurement limit. Syn: overload response performance test: An evaluation of the performance of an instrument in response to a given influence quantity point of measurement: Place where the conventionally true values are determined and where the reference point of the instrument is placed for test purposes precision: Degree of agreement of repeated measurements of the same parameter range: All values lying between the lower and upper detection limits reading: The indicated or displayed value of the readout readout: The portion of the instrument that provides a visual display of the response of the instrument or the displayed value, with units, displayed and/or recorded by the instrument as a result of the instrument s response to some influence quantity. 6

19 reference point of an instrument: Physical mark, or marks, on the outside of an instrument used to position it at a point where the conventionally true value of a quantity is to be measured, unless the position is clearly identifiable from the construction of the instrument relative error [ε REL (%)]: The difference between an instrument s reading, M, and the conventionally true value, CTV, of the quantity being measured divided by the conventionally true value multiplied by 100. ε REL (%) = [(M CTV) (CTV)] response: Ratio of the instrument reading to the conventionally true value of the measured quantity response time: The time interval required for the instrument reading to change from 10% to 90% of the final reading or vice versa, following a step change in the radiation field at the detector restricted mode: An advanced operating mode that can be accessed by an expert user (e.g., via password) to control the parameters that can affect the result of a measurement (e.g.,radionuclide library, routine function control, calibration parameters, alarm thresholds). NOTE May be called the advanced or expert mode routine test: Test that applies to each independent instrument to ascertain compliance with specified criteria standard deviation: The positive square root of the variance standard instrument or source: (A) National standard a standard determined by a nationally recognized competent authority to serve as the basis for assigning values to other standards of the quantity concerned. In the U.S., this is an instrument, source, or other system or device maintained and promulgated by the National Institute of Standards and Technology (NIST). (B) Primary standard a standard that is designated or widely acknowledged as having the highest metrological qualities and whose value is accepted without reference to other standards of the same quantity. (C) Secondary standard a standard whose value is assigned by comparison with a primary standard of the same quantity. (D) Reference standard a standard, generally having the highest metrological quality available at a given location or in a given organization, from which measurements made there are derived. (E) Working standard a standard that is used routinely to calibrate or check material measures, measuring instruments, or reference materials. A working standard is traceable to NIST (see ANSI N42.22 and ANSI N42.23) standard test conditions: The range of values of a set of influence quantities under which a calibration or a measurement of response is carried out test: A procedure whereby the instrument, circuit, or component is evaluated type test: Initial test of two or more production instruments made to a specific design to show that the design meets defined specifications uncertainty: The estimated bounds of the deviation from the conventionally true value, generally expressed as a percent of the mean, ordinarily taken as the square root of the sum of the square of two components: 1) Random errors that are evaluated by statistical means; and 2) systematic errors that are evaluated by other means upper measurement limit (UML): The UML is the maximum level at which the instrument meets the required accuracy. 7

20 variance (σ 2 ): A measure of dispersion, which is the sum of the squared deviation of observations from their mean divided by one less than the number of observations. 2 σ 1 n = n 1 i = 1 ( x x) 2 i 3.2 Definitions of particular relevance to ANSI N acceptable identification: When a monitor identifies the radionuclide(s) of interest or that radionuclide(s) and expected daughter(s), and no others alarm assembly: Equipment designed to indicate visually, audibly, or both, that the measured material has generated an alarm alarm criteria: Conditions that cause a monitor to alarm. NOTE For portal monitors without the ability to identify radionuclides, alarm threshold settings are typically based on the gamma-ray or neutron count rates obtained during an occupancy or measurement cycle and also the ambient background. Spectroscopy-based portal monitors also have the ability to activate or not activate an alarm based on the identified radionuclide(s) as desired by the user confidence indication: An indication provided by the monitor of the reliability assigned to the determined identification detection assembly: The monitor enclosure that includes the detector, the associated electronics and the mounting components detection zone: The region that is either located between opposing detection assemblies or adjacent to a detection assembly over which the detection requirements are satisfied. NOTE Annex A shows a diagram of the detection zone efficiency: the net number of counts registered by the detector per unit time divided by the number of photons of interest originating from the radioactive source that is being measured during the same unit of time evaluation distances: The distance between an evaluation test source and the exterior face(s) of the detection assembly(s) full width at half maximum (FWHM): The full width of a distribution measured at half the maximum ordinate local: Within close proximity to the detection assembly(s) manufacturer: Includes the designer of the equipment NORM: Naturally-occurring radioactive material occupancy: When the detection zone is occupied with an object (person, vehicle, package, etc.) that is being monitored. 8

21 portal monitor: A radiation measurement device designed to detect changes in the measured exposure rate as an object passes through or is placed in an area that is adjacent to a radiation detection assembly or assemblies purchaser: Includes the user of the equipment radioactive material: In this standard, radioactive material includes special nuclear material unless otherwise specifically noted reference point of the detection zone: The reference point of the detection zone is that point that is at the center of the detection zone in both axes (horizontal and vertical) at a distance from the detection assembly based on the monitor type given by the evaluation distance (see Table 1). The z-axis or depth position is determined based on the width (related to object flow) of the detection assembly remote station: A computing system or subsystem used for data archiving, control, annunciation, printing, or other functions for portal monitor assemblies, typically located at a distance from the portal monitors spectroscopy-based portal monitor: A portal monitor that uses gamma spectroscopy techniques for the identification of radionuclides standard test sources: A set of NIST-traceable radiation sources required to perform an evaluation. 4. General considerations All tests are to be considered type tests unless otherwise specified in an individual step. If the manufacturer claims a broader range of operation (for example, an operating temperature range of 30 C to +55 C) and the user requires this range, then additional testing and verification should be agreed upon between the manufacturer and customer. Certain tests may be considered as acceptance tests by agreement between the customer and manufacturer. 4.1 Standard test conditions Except where otherwise specified, the tests in this standard shall be carried out under the standard test conditions shown in Table 4. For those tests intended to determine the effects of variations in the influence quantities, all other influence quantities should be maintained within the limits for standard test conditions given in Table 4 unless otherwise specified in the test procedure concerned. 4.2 Units and uncertainties For the purposes of this standard, the radiological units of exposure rate (R/h) shall be used for x-ray and gamma-ray radiation. Exposure rate can be converted to air-kerma rate by using the following conversion factor: 1R/h = 876 mrad/h (8.76 mgy/h). For x-rays and gamma-rays the factor to convert from absorbed-dose-to-tissue (rad) to dose equivalent (rem) is equal to 1. Therefore, in conventional units 1 rad = 1 rem and in SI units 1 Gy = 1 Sv. Conversion coefficients can be used to convert from air-kerma to dose equivalent. The conversion coefficients are tabulated as a function of photon energy as described in ISO/IEC

22 Throughout the text, radiological quantities are expressed in conventional units; SI units are given in parentheses. If uncertainties are not specified they shall be set to ±5%. 4.3 Special word usage The following word usage applies: The word shall signifies a mandatory requirement (where appropriate, a qualifying statement is included to indicate that there may be an allowable exception). The word may signifies an acceptable method or an example of good practice. The word should signifies a recommended specification or method. 5. Design requirements 5.1 General characteristics The equipment addressed by this standard shall detect changes in exposure rates and identify radionuclide(s) in objects, containers, vehicles, or pedestrians when the signal from the detection system meets an alarm condition (exposure rate or identification results). Measurement occurs when an object passes through the detection zone or with an object stationary within the detection zone where the user performs controlled analyses of the object (i.e., enters collection time and activates the count). Monitors shall be capable of operating independently of any peripheral device or remote station and shall be unaffected by any malfunction of a peripheral device. The monitor shall be able to operate for up to 3 h if there is a loss of external power and/or data transfer capabilities to the remote station. Operations shall include storing measurement data at the monitor. According to their use, spectroscopy-based portal monitors are classified as follows: Pedestrian Package (e.g., conveyor) Vehicle (including containerized cargo) Rail vehicle The detection zone is the area located adjacent to, or between, one or more detection assemblies where the measurement of radiation takes place. The size of the detection zone is based on the classification of use. If a monitor is used in two or more classifications, its associated detection zone shall be appropriate for each classification. The monitor shall meet the performance requirements of this standard when installed as tested. Operational conditions such as separation distance and background radiation shall be considered when installing a radionuclide-identifying portal monitor. The manufacturer shall state the distances at which the monitor meets this standard, if the distances are different than those stated in the document. 10

23 The reference point of the detection zone is located at the evaluation distance listed in Table 1 and centered in both the height and width orientations of the detection zone. Table 1 Evaluation distances for different applications Monitor type Distance between detection assemblies Evaluation distance Single-sided vehicle monitors (includes containerized cargo) Multiple sided vehicle monitors (includes containerized cargo) N/A Monitors 5 m apart measured from the surface of each detection assembly. Source 5 m from assembly Centered between detection assemblies Single-sided pedestrian or package monitors N/A Source 1 m from detector Fixed dimension pedestrian or package monitors Multiple sided pedestrian or package monitors N/A Monitors 1 m apart measured from the surface of each detection assembly. Centered between detection assemblies Centered between detection assemblies Single-sided rail vehicles monitors N/A Source 6 m from assembly Multiple-sided rail vehicle monitors Monitors 6 m apart measured from the surface of each detection assembly. Centered between detection assemblies Pedestrian Pedestrian monitors shall provide a detection zone to ensure that people are monitored. As a minimum, the range of the detection zone shall be from 0.1 m to 2 m above the ground. The recommended distance between detection assemblies for evaluation purposes is listed in Table 1 or if fixed, is given by the manufacturer. Pedestrian monitors may use a single detection assembly (single-sided) or multiple opposing detection assemblies with or without detectors across the top and/or bottom part of the detection assembly. For monitors with a restricted passage height, the height of the detection zone shall be from the ground or base surface to the top surface of the monitor s detector. The passage or transit speed for testing shall be the speed listed in Table 2. Table 2 Speed of moving sources Monitor type Source speed Occupancy time for test Vehicle monitors (except rail) 8 km/h 5 s Pedestrian monitors 1.2 m/s 1 s Package or conveyor monitor 1.2 m/s 1 s Rail vehicle monitors 8 km/h 5 s 11

24 5.1.2 Vehicle (includes road-transported containers) Vehicle monitors shall provide a detection zone that ensures that the entire vehicle is monitored during passage. As a minimum, the range of the detection zone shall be from 0.2 m to 4.5 m above ground. For monitors with a restricted passage height, the height of the detection zone shall be from 0.2 m to the top surface of the monitors detector. The distance between vertical monitors for evaluation purposes is listed in Table 1 or provided by the manufacturer if the monitor is an assembly that has the detection assemblies at a fixed distance apart. The passage speed for testing shall be the speed listed in Table Rail vehicle (includes rail-transported containers) Rail vehicle monitors shall provide a detection zone that ensures that the entire rail vehicle is monitored during passage. As a minimum, the range of the detection zone is from 0.3 m to 6 m above the rail (For test purposes, the ground surface should be considered as the top of the rail). (See ANSI N42.35.) For monitors with a restricted passage height, the range of the detection zone shall be from 0.3 m to the top surface of the monitors detector. The distance between vertical monitors for evaluation purposes is listed in Table 1 or, if fixed, is given by the manufacturer. The passage speed for testing shall be the speed listed in Table Package (or conveyor monitor) Package or conveyor monitors shall provide a detection zone that ensures that items moving through the detection zone are monitored. Monitors may use a single detection assembly (single-sided) or multiple opposing detection assemblies which may have detectors across the top and/or bottom part of the detection assembly (multi-sided). As a minimum, the height of the detection zone shall be either (1) from the base surface to 1 m above the base surface (that surface which corresponds to the ground or conveyor bottom surface) for detectors mounted below the base surface, or (2) from the base surface to the face of the detection assembly for detectors mounted 1 m above the base surface. For monitors with a restricted passage height, the range of the detection zone shall be from the base surface to the manufacturer-stated height. The passage speed for testing shall be the speed listed in Table Physical configuration Enclosure(s) provided for outdoor assemblies shall be designed to meet IP54 classification as designated in IEC Vent holes are permitted if required by the manufacturer. The detection assemblies for road and rail vehicle monitoring may be subjected to vibration. Monitors and installation techniques (e.g., concrete pads, support brackets) shall be designed to prevent normal vibrations and shocks from interfering with the operation of the detection system. Controls and adjustments which affect calibration and alarm settings shall be designed so that access to them is limited to authorized people. Provisions shall be made to permit testing of visual and/or sound warning indicators without the use of radiation sources. Detector response evaluations shall be performed without the benefit of any radiation shielding against the natural background, except for that shielding which is a permanent feature of the monitor or if it is required for a specific test. 12

25 5.3 Spectral identification a) b) c) d) e) f) g) h) A displayed gamma-ray spectrum is not required during routine operation. The spectrum display shall be available by manufacturer-defined user actions. The monitor shall have the ability to internally store at least 1000 complete occupancy data sets. For monitors that do not use occupancy sensors, the monitor shall have the ability to store 3 h of measurement data as defined in item c). Each occupancy data set shall contain collection and identification results information including: 1) 2) 3) 4) 5) 6) 7) 8) 9) 10) 11) 12) Unprocessed spectrum (spectra for multi-detector systems) obtained during a single occupancy Time and date Real time for alarm spectrum Run time for alarm spectrum Identified radionuclides, categories, and confidence level (if available) Occupancy time Monitor identification Alarm condition (gamma-ray and/or neutron) Background (gamma-ray and neutron) count rate and spectrum (includes real time and run time) Gamma-ray count rate Neutron count rate Vehicle speed (if available) The data format shall comply with ANSI N42.42 requirements. The monitor shall have the ability to store background count rate and spectra, and transfer that information at user selectable intervals to an external device, such as a computer. The monitor shall have the ability to store gamma-ray and neutron count rate time-history data. An indication shall be displayed or otherwise provided (e.g., not identified ) if a radionuclide cannot be identified when or after a measurement takes place. If a reliability or confidence level is associated with the identification of a radionuclide(s), the confidence level shall be provided in the data set and the manufacturer shall describe the meaning of the displayed value. The monitor shall have the ability to perform identification measurements with an object stationary in the detection zone. This function shall be user selectable and does not supersede the requirements stated in 6.8. The recommended measurement time shall be stated by the manufacturer and should be less than or equal to 1 min. 13

26 5.4 Indication features The monitor shall provide an indication of its operational status and alarm condition, and shall be capable of transmitting these signals to additional remote stations. The user shall have the ability to select the visibility of the status indication. All alarm indicators shall automatically or manually reset as defined by the user. 5.5 Occupancy and speed sensors for vehicle monitors Monitors shall have the ability to support occupancy sensors and should have the ability to measure speed. If used, occupancy and speed sensors: Shall be able to detect presence and estimate vehicle speed, indicate if a vehicle stops within the detection zone, and not count a single vehicle or object in the detection zone more than once Should be capable of operating on a mix of traffic (e.g., cars, vans, pickup trucks, buses, cargo trucks, trains) Should function under all environmental conditions stated in this standard Rail monitors should have the ability to approximate the location of an alarm when monitoring multi-car trains. For test purposes, a system that incorporates an occupancy sensor should have the ability to perform a userselected series of consecutive occupancies automatically without the need to activate the occupancy sensor. Function variables such as occupancy time and time between occupancies shall be user-selectable. 5.6 Markings Internal controls shall be identified by markings on electrical circuit boards and/or individual components, and identification in technical manuals. Markings shall be permanently fixed under normal conditions of use. Exterior markings shall be limited to the manufacturer s unique serial number, voltage and current requirements, if equipped with an outlet plug, and shall meet minimum applicable municipal, state, federal, and international code requirements. 5.7 Power supply Requirement Line-operated assemblies should be designed to operate from a single-phase AC supply voltage of 100 V to 240 V and from 47 Hz to 63 Hz. The monitor shall be able to operate, including storing measurement data for a minimum of 3 h, if there is a loss of external power. Compliance shall be based on tests performed at the reference temperature of 22 C. See also

27 5.7.2 Test method Place the 137 Cs and 252 Cf test sources in a location that provides a stable response. With the supply voltage at its nominal value, determine the mean gamma-ray and neutron readings from a sufficient series of readings and perform a ten-trial radionuclide identification of 137 Cs. Record the results as x correct for ten trials. Increase the supply voltage to 12% above the nominal value. Determine and record each channel s mean reading and perform a ten-trial radionuclide identification using 137 Cs. Decrease the supply voltage to 12% below the nominal value and again determine and record the mean readings, and perform a ten-trial radionuclide identification Repeat the previous tests at the nominal supply voltage with the line frequency at 3% above and 3% below the nominal frequency (58 Hz to 62 Hz). For this test, the results from each voltage or frequency test point from each series of identifications shall be the same or better than the identification results obtained at the nominal voltage and frequency. For example, if the ten trial results at nominal voltage and frequency are correct in six out of ten trials, the results at each test point shall be six or more correct to be acceptable. For the gross response channels, the results are acceptable if the mean readings obtained at each voltage or frequency test point are within ±15% of the mean readings obtained at the nominal voltage and frequency. 5.8 Battery life-time Requirement Monitors shall be able to operate including storing measurement data for up to 3 h if there is a loss of external power Test method Monitors shall be placed under standard test conditions, switched on, and allowed a stabilization and background detection period as specified by the manufacturer. Disconnect the AC line, and using only 133 Ba(g), perform an occupancy at 10 s intervals following the guidance found in step 6.3 with the source passing through the mid-point of the detection zone at the speed appropriate for the monitoring system being tested. Perform the test for 3 h. To be acceptable, the monitor shall perform within specifications for the entire 3 h period and shall have stored all the required information from each occupancy. The low-battery indication shall not have activated during the period. 5.9 Protection of switches Switches and other controls should be designed to ensure that the monitor can be operated properly while minimizing accidental switch operation Effective range of measurement The effective gamma-ray energy response range shall be stated by the manufacturer, and should be at least 25 kev to 3 MeV. The manufacturer shall state the range for gamma-ray count rate measurement and for neutron count rate indication. 15

28 5.11 Software and data analysis Communications protocol and data format The monitor shall have the ability to transfer data to an external device, such as a computer. The transfer shall be based on a commonly available technology such as Ethernet, USB, RS-232, wireless (e.g., ), or RS-485. Consideration should be given to data security when using wireless data transfer techniques. When used, wireless techniques shall have the ability to be encrypted. The transfer protocol and format shall be fully described in the technical manual and shall also be freely distributable. Data format shall be as defined in ANSI N User interface Visual indicators The monitor should provide a color-based visual indication for the following actions: Alarm color Red Blue Orange Amber Green White Type Neutron alarm SNM identification and user-selectable high-radiation alarms Other gamma-ray alarms (e.g., NORM) System error/failure Power/system Okay Checking Warning indicators The following indications shall be provided at the user interface as a minimum. Background changes during non-occupancies that can affect the overall sensitivity of the monitor High-low detector count rate conditions Energy stabilization invalid or not acceptable Occupancy sensor failure, if occupancy sensors are used Changes in operational status (e.g., occupied, alarm, monitoring background, fault, blocked) Loss of line power Battery status 16