1、ANSI N42.30-2002IEEE StandardsN42.30American National Standard forPerformance Specification for TritiumMonitorsPublished by The Institute of Electrical and Electronics Engineers, Inc.3 Park Avenue, New York, NY 10016-5997, USA25 November 2002Accredited by the American National Standards InstituteSpo
2、nsored by theNational Committee on Radiation Instrumentation, N42IEEE StandardsPrint: SH95014PDF: SS95014The Institute of Electrical and Electronics Engineers, Inc.3 Park Avenue, New York, NY 10016-5997, USACopyright 2002 by the Institute of Electrical and Electronic Engineers, Inc.All rights reserv
3、ed. Published 25 November 2002. Printed in the United States of America.Print: ISBN 0-7381-3345-0 SH95014PDF: ISBN 0-7381-3346-9 SS95014No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission from the publisher.A
4、NSI N42.30-2002American National Standard for Performance Specification for Tritium MonitorsSponsorNational Committee on Radiation Instrumentation, N42Accredited by the American National Standards InstituteSecretariatThe Institute of Electrical and Electronics Engineers, Inc.Approved 25 September 20
5、02American National Standards InstituteAbstract: The performance requirements for tritium monitors used for monitoring airborne tritium radioac-tivity are provided in this standard. It also provides test methods for establishing a monitors performance characteristics.Keywords: airborne tritium, moni
6、tors, radioactivity, tritiumAmerican National StandardAn American National Standard implies a consensus of those substantially concerned with its scope and pro-visions. An American National Standard is intended as a guide to aid the manufacturer, the consumer, andthe general public. The existence of
7、 an American National Standard does not in any respect preclude any-one, whether he has approved the standard or not, from manufacturing, marketing, purchasing, or usingproducts, processes, or procedures not conforming to the standard. American National Standards are subjectto periodic reviews and u
8、sers are cautioned to obtain the latest editions.CAUTION NOTICE: This American National Standard may be revised or withdrawn at any time. The pro-cedures of the American National Standards Institute require that action be taken to affirm, revise, or with-draw this standard no later than five years f
9、rom the date of publication. Purchasers of American NationalStandards may receive current information on all standards by calling or writing the American NationalStandards Institute.Authorization to photocopy portions of any individual standard for internal or personal use is granted by theInstitute
10、 of Electrical and Electronics Engineers, Inc., provided that the appropriate fee is paid to CopyrightClearance Center. To arrange for payment of licensing fee, please contact Copyright Clearance Center, Cus-tomer Service, 222 Rosewood Drive, Danvers, MA 01923 USA; +1-978-750-8400. Permission to pho
11、to-copy portions of any individual standard for educational classroom use can also be obtained through theCopyright Clearance Center.Copyright 2002 IEEE. All rights reserved. iiiIntroduction(This introduction is not part of ANSI N42.30-2002, American National Standard for Performance Specification f
12、or Tri-tium Monitors.)This standard is the responsibility of the Accredited American Standards Committee on Radiation Instru-mentation, N42. Committee N42 delegated the development of this standard to Subcommittee N42.RPI.Drafts were reviewed by Committee N42, Subcommittee N42.RPI, and other interes
13、ted parties; and thecomments were utilized in producing the standard as finally approved. This standard was approved on N42letter ballot of 25 September 2002. ParticipantsAt the time Committee N42 approved this standard, it had the following members:Louis Costrell, ChairMichael P. Unterweger, Vice c
14、hairSue Vogel, Administrative SecretaryOrganization Represented Name of RepresentativeAmerican Conference of Governmental Industrial HygienistsJesse LiebermanBattelle NW Laboratories Joseph C. McDonaldBicron. Richard P. OxfordChew, M. H Jack M. SelbyEberline Instruments Mitchell TruittEntergy-ANO.Ca
15、rl R. SiebentrittFemo-TECH, Inc. Richard StraubGamma-Metrics .Ernesto A. CorteHealth Physics Society.George CampbellJoseph R. Stencel (Alt.)Institute of Electrical and Electronics Engineers (IEEE).Louis CostrellJulian Forster (Alt.)Anthony J. Spurgin (Alt.)Lawrence Berkeley National Laboratory. Edwa
16、rd J. LampoLawrence Livermore National Laboratory Gary JohnsonLovelace RR Institute Morgan CoxMassachusetts Institute of Technology, Bates Linear Accelerator Center, RPO . Frank X. MasseNational Institute of Standards primary power source, system interface (output), and measurement range: Low-range
17、tritium monitors include monitors that have a range, R, of 0 R 1000 Ci/m3(Bq/m3). High-range monitors have a range of 0 R X, where X is the maximum response of the monitor asstated by the manufacturer. Installed tritium monitors typically have outputs that interface the monitor with a centralized ra
18、dia-tion monitoring system to initiate alarms or indicate operating faults. Installed monitors operateusing line power primarily and may have battery backup. Portable monitors could also have the ability to interface with a centralized system, but use batterypower primarily. They can also use line p
19、ower through an internal or external converter and are typ-ically carried from location to location for use.4.1.1 Effective range of measurement4.1.1.1 DiscussionIt is well known that measurements obtained from low levels of radiation are random. The randomness isprimarily caused by the radiation le
20、vel as well as a monitors ability to collect enough information within anacceptable time interval. The manufacturer is required to state the overall response range of the monitor. Itshould be from the lowest to highest displayed reading. Unfortunately, this response range is typically notpossible wi
21、th radiation-measuring devices. The point at which the monitors response becomes more ran-dom than what is acceptable is effectively the lowest response or the lowest point of the effective range ofmeasurement. This point can also be loosely called minimum detectable activity (MDA). At this point, i
22、twould be difficult to discern between the randomness of the ambient radiation and an actual increase inactivity.See 6.3 for information about how to determine the MDA for tritium monitors. 4.1.1.2 RequirementsFor analog meters, the effective range of measurement should be from 10% of the maximum re
23、ading of thelowest range or decade to 100% of the monitors stated response range.For digitally scaled assemblies, the effective range should be from the start of the second least significantdigit (LSD) to the full range of indication available i.e., if the stated response range was 0 to 1000 Ci/m3(B
24、q/m3), the effective range of measurement is 2 Ci/m3(Bq/m3) to 1000 Ci/m3(Bq/m3).ANSIPERFORMANCE SPECIFICATION FOR TRITIUM MONITORS N42.30-2002Copyright 2002 IEEE. All rights reserved. 74.2 Measurement principle A wide range of measuring techniques are available for measuring tritium-in-air levels.
25、These techniquesinclude flow-through ionization chambers and gas-flow proportional counters with a range of compensationtechniques for minimizing the response to background gamma radiation or other radioactive gas. Inlet filtersshould be incorporated to minimize the response to radioactivity from ae
26、rosols or particulates present. Watervapor traps may be used either to eliminate tritiated water vapor prior to the detector assembly (in equipmentmeasuring tritiated water vapor selectively by difference techniques) or to concentrate the tritium in amedium that is subsequently passed through a dete
27、ctor assembly. The choice of technique in any particularsituation will be influenced by the particular circumstances at the facility concerned.4.3 Equipment description Tritium monitor components may be grouped into two assemblies, which may be associated or separatedaccording to the monitoring and
28、operating requirements. These two assemblies are the sampling and detec-tion assembly and the control and measurement assembly.4.3.1 Sampling and detection assemblyThe sampling and detection assembly includes, where applicable, some or all of the following components: Sampling and exhaust tubes Inle
29、t filter Tritiated water vapor trap Facilities for drawing samples for laboratory analysis or for calibration tests with radioactive gases Air/counting gas mixing devices (for proportional counters) Radiation detector Electronic measuring components including electronic background compensation devic
30、e Ambient gamma radiation shielding or compensation device Humidity controls (i.e., heat trace) to minimize condensation Air/flow rate monitoring and control devicesAir pump4.3.2 Control and measurement assemblyThe control and measurement assembly includes, where applicable, the following components
31、: Electrical control and supply components Signal measurement circuitry Display and/or recording components Warning signals and alarm components4.4 Ease of decontamination The monitor shall be designed to limit external and internal contamination. The sampling and detectionassembly shall have smooth
32、, nonporous surfaces. In-line filtering media shall be available to prevent theingress of particulate contamination into the chamber. The external surface of the monitor shall be madefrom material that will allow easy decontamination. Filtering or trapping devices shall be easy to dismantleand decon
33、taminate.ANSIN42.30-2002 AMERICAN NATIONAL STANDARD FOR8 Copyright 2002 IEEE. All rights reserved.4.5 Operating noise levelOperating noise is typically caused by the air pump. The manufacturer shall select components and designthe monitor in such a way that the resulting acoustic noise level satisfi
34、es the requirements of the user. In anycase, the noise level shall not impede the ability of the user to hear the alarm.4.6 Mass and dimensions As far as possible, an attempt shall be made to minimize the mass and dimensions of the equipment, particu-larly for portable monitors. The mass and dimensi
35、ons shall be specified by the manufacturer.4.7 Units of readoutThe units of readout shall be based on the requirements of the user. As a minimum, the display shall have thecapability to indicate radioactivity in becquerels and have the capability to display volume in cubic centime-ters, cubic meters
36、, or liters. Other values such as MPC or DAC should be available depending on the usersrequirements. The activity units may be permanently indicated as an exterior marking near the display.4.8 MarkingsAll instrument controls, displays, and adjustments, both internal and external, shall be identified
37、 as tofunction.4.8.1 Exterior markingsExternal markings shall be easily readable and remain permanently affixed under normal conditions of use.The following markings shall appear on the exterior of the monitor: Instrument type Manufacturer and model number Unique serial number Control functions Cham
38、ber location Check source placement position Power requirements Readout units, when applicable4.9 Alarm thresholdMonitors shall be equipped with audible and visual alarms. Alarm thresholds shall be adjustable to any pointwithin the range of the monitor.4.10 Alarm capabilitiesThe overall alarm and in
39、dication capabilities shall be appropriate to the use and location of the monitor. Por-table monitors may not require extensive alarm output capabilities whereas installed monitors typically dorequire many outputs for connection to a central radiation monitoring system.All alarm circuits shall give
40、visual indication locally on the monitor and also operate outputs for use with anexternal alarm. Local alarms shall be audible with a local-acknowledge (silence) switch. Means to acknowl-edge an alarm remotely should be available. Audible alarms shall be at least 10 dB to 15 dB above the back-ANSIPE
41、RFORMANCE SPECIFICATION FOR TRITIUM MONITORS N42.30-2002Copyright 2002 IEEE. All rights reserved. 9ground noise level at a frequency of 500 Hz to 3000 Hz, should be compatible with the users requirementfor alarm sounds, and shall not exceed 85 dB at distances 3 m. Provision should be made to allow i
42、nternaldeactivation of the audible alarm feature. All alarm functions shall be provided with test facilities to allowchecking of alarm operation.In the case of adjustable alarms, it shall be possible to check an alarms operation over the range of adjust-ment, with indication of the actual alarm oper
43、ation point. Alarm circuits shall be able to hold the alarm sig-nal until reset by a reset control or to autoreset when the alarm state no longer exists. The two modes ofoperation shall be available by simple modification on all equipment. The alarm capabilities in 4.10.1 and4.10.2 shall normally be
44、 provided. 4.10.1 High radioactivity alarmThe high radioactivity alarm shall have an adjustable threshold (set point) that is within 5% of the indi-cated reading when activated. The alarm shall activate a light and output device. The alarm light shallremain on after the audible alarm is acknowledged
45、.The actual alarm set point shall not deviate from the indicated set point level by more than 5%. The usershall have the ability to select whether the alarm is latching or nonlatching. Nonlatching alarms shall auto-matically extinguish within 30 s after the measured radioactivity level returns to a
46、level that is below thealarm set point.4.10.2 Failure alarmsFailure alarms shall be available for as many electronic circuit or mechanical device faults as practical.Wherever practicable, separate indication of the source of the fault shall be given.a) Low airflow alarm. The low airflow alarm shall
47、have an adjustable set point that is within 5% ofthe maximum flow rate value and shall activate a light and output. The alarm shall be activated fromno or out-of-tolerance airflow or from out-of-tolerance differential pressure.b) Power failure alarm. The monitor shall have the ability to issue an al
48、arm upon loss of power. Thisalarm shall be fail-safe, opening a contact or other equivalent action upon loss of power.c) Trouble alarms. Trouble alarms shall be activated from loss of high voltage or no radiation responseor from the failure of any component or circuit that would affect the ability o
49、f the monitor to func-tion correctly. Trouble alarms shall include a light and an output for remote indication and shall bedistinguishable from the high radioactivity alarm.4.11 Protection of switches and controlsSwitches and controls, especially zero, shall be protected from inadvertent operation. The zero controlshould not be operable while the monitor is performing a measurement, unless it is used as compensation forchanges in ambient gamma radiation levels. If the zero control is used for gamma compensation, precautionsshall
