ANSI HPS N13.1-2011 Sampling and Monitoring Releases of Airborne Radioactive Substances from the Stacks and Ducts of Nuclear Facilities.pdf

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1、 American National Standard ANSI/HPS N13.1-2011 Sampling and Monitoring Releases of Airborne Radioactive Substances from the Stacks and Ducts of Nuclear Facilities Approved: March 30, 2011 American National Standards Institute, Inc. Published by Health Physics Society 1313 Dolley Madison Blvd. Suite

2、 402 McLean, 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 N13.

3、1-2011 iii The 2011 version of this standard is a re-affirmation of the 1999 version, performed under the authority of the Health Physics Society Accredited Standards Committee (ASC) N13, Radiation Protection. The Working Group responsible for this standard had the following members: John A. Glissme

4、yer, Chairman (Pacific Northwest National Laboratory) Brian Asamoto (General Atomics Electronic Systems, Inc.) J. Matthew Barnett (Pacific Northwest National Laboratory) Brent C. Blunt (Savannah River Nuclear Solutions) Eric Darois (Radiation Safety the fifth sentence in 4.4, paragraph 6 is highligh

5、ted as follows: The precision shall should be estimated at the 95% confidence level. 21 To correct a missing verb in clause 4.4.1, paragraph 1, second sentence, the sentence is changed from: There are no hard and fast rules concerning how these levels set. to read: There are no hard and fast rules c

6、oncerning how these levels are set. 36 To correct the omission of a minus sign in Equation 7, the equation is changed from: Tr= Ae(1 Wl) to read: Tr= Ae(1 Wl) 39 An inconsistency is noted between clause 6.4.1 and the requirement in Table 6; the third sentence of the third paragraph of clause 6.4.1 i

7、s highlighted as follows: The penetration of 10 m AD aerosol particles from the free stream to the collector or analyzer should shall be known and should shall not be less than 50%. 41 An inconsistency is noted between clause 6.5 and the requirement in Table 6; the sixth sentence of the fourth parag

8、raph of clause 6.5 is highlighted as follows: The minimum transport efficiency for vapor or gas samples from the free stream to the collector/analyzer should shall be 50%. 50 To correct a typographical error in the last bullet label of clause 7.5, the last bullet is changed from: e. leak tests. to r

9、ead: f. leak tests. 52 To correct an inconsistency between the units of the requirement in Table 5, column 2, and the units of the requirement in clause 6.4.6, the units for surface density are changed from: 1 g/cm3xiii to read: 1 g/m2 55 To correct an inconsistency between the requirement in Table

10、6 and the requirement in the referenced clause 6.3.2, the third item in Table 6 is changed from: Sampler nozzle shall have an aspiration ratio that does not exceed 150% for 10 m AD particles to read: Sampler nozzle shall have an aspiration ratio within range of 0.80 to 1.50 for 10 m AD particles 67

11、To correct an inconsistency between the 8th input parameter in Table B.1 and the third sentence in clause B.2, the 8th input parameter in Table B.1 is changed from: b. shroud diameter should be 52.5 mm to read: b. shroud diameter should be 52.8 mm 67 To correct an inconsistency between the 9th input

12、 parameter in Table B.1 and the graphical representation of that parameter shown in Figure B.3 on page 66, the 9th input parameter in Table B.1 is changed from: Element 2: Tube, 0.2 m long, 0 from horizontal to read: Element 2: Tube, 0.2 m long, 90 from horizontal 76 To correct an inconsistency betw

13、een Equation E-2 and Equation E-1, the left-hand variable name in Equation E-2 is changed from: CAto read: cA76 To correct an inconsistency between the Greek letters used in Equations E-3 and E-4 and the Greek letters used in the last sentence of the page: phis in the last sentence are changed to: t

14、hetas 80 To correct a cross-reference error in the second sentence of the third paragraph of clause E.4.1: annex H is changed to read: annex G 89, 90 To correct an inconsistency between the particle diameter notation used in clause G.3 and the particle diameter notation used in the stated references

15、: MMD is changed throughout items 4 and 5 to read: MMADxiv Foreword to the 1999 version (This foreword is not part of American National Standard N13.1-2011.) Monitoring of radionuclide emissions from stacks and duc ts must provide results that are representative of the content and concentration of t

16、he gas stream as a whole. For extractive sampling this requires that a sampling point must be in a region where the contaminant is well mixed with the bulk flow, and that the process of extraction does not bias the sample. In the 1969 version of ANSI N13.1, an attempt was made to meet the mixing goa

17、l by prescribing the location in a stack or duct where sampling could be performed in terms of the number of duct diameters from a flow disturbance. With the realization that in many circumstances conformance with a duct length rule would not in itself guarantee achievement of good mixing, another r

18、ule was recommended, namely that the extraction process be accomplished with multiple sampling nozzles in any stack or duct with a diameter greater than 150 mm (6 inches). The number of sampling points was dependent on duct diameter. Further, if aerosol particles with sizes greater than 2 to 5 m cou

19、ld be present in the air stream, it was recommended that the inlet to the sampling nozzle be operated isokinetically. However, the use of multiple isokinetic nozzles to sample aerosol particles can be counterproductive. For a fixed sampling flow rate, as the number of sampling points is increased th

20、e inlet diameter of each isokinetic nozzle is decreased, which causes larger losses in the entrance region of the nozzles. It is now known that the early rule-based approach (selection of an acceptable sampling location using a prescribed number of duct diameters from a disturbance, and on the requi

21、rement for multi-point isokinetic extraction of particulate samples) does not provide assurance that a sample will be representative. This revision of ANSI N13.1 differs significantly from the earlier version in that it is now a performance-based standard rather than one based on prescriptive rules.

22、 There are two important aspects of performance addressed in the new approach. First, the concept of acquiring a representative sample is not based on rules for sample location and multi-point extraction, but rather on the premise that at any location where the contaminant concentration and the flui

23、d momentum can both be de monstrated to meet numerical criteria for acceptable mixing, a representative sample can be obtained by extraction from a single point in that profile. Thus, the burden has properly shifted from specifying the distance that a sampling location must be from a disturbance to

24、demonstrating compliance with numerical criteria placed on mixing performance. Second, numerical criteria are also used to provide the basis for a decision on whether a sampling system will deliver a representative sample to a collector or detector. Essentially the concept of isokinetic sampling has

25、 been replaced by numerical criteria for the sampling performance of extraction nozzle and transport line designs. By eliminating the requirement for multi-point isokinetic sampling and focusing instead on quantitative performance, the design of sampling systems with much lower sample losses is now

26、possible. The complete set of numerical criteria has been shown to be achievable by a new generation of sampling system designs, and these criteria are expected to accommodate the application of any innovative concepts that are based on sound principles of aerosol physics and fluid mechanics. Althou

27、gh the approach to achieving representative effluent sampling presented in this standard represents a substantial departure from the methodology recommended by the previous version of this standard, it is practical and the expected performance is attainable. AMERICAN NATIONAL STANDARD ANSI/HPS N13.1

28、-1999 1 Sampling and Monitoring Releases of Airborne Radioactive Substances From the Stacks and Ducts of Nuclear Facilities 0 Introduction ANSI/HPS N13.1 was first issued in 1969 as a guide to sampling airborne radioactive materials in the ducts, stacks, workplaces, and environs of installations whe

29、re work with radioactive materials is conducted. Since then, an improved technical basis has been developed for each of the major sampling specialties. Consequently, the scope of this revision has been narrowed to directed airflow situations such as ducts and stacks. This standard presents a new app

30、roach to representative sampling. The goal of achieving an unbiased, representative sample is accomplished by requiring that samples are extracted from airstreams meeting rigorous criteria for being well mixed for potential airborne contaminants. This standard sets forth guidelines and performance c

31、riteria for the proper use of air sampling nozzles, transport lines, sample collection and monitoring devices, and gas flow measuring methods in obtaining valid measurements of airborne radioactive materials in ducts or stacks. The guidelines and criteria presented in this standard are covered in th

32、e following clauses: Clause 3 provides a glossary and nomenclature used in this standard to define terms and symbols that are used in the equations. Clause 4 covers the objectives and approaches for sampling programs. Clause 5 discusses the requirements for selecting sampling locations. Clause 6 cov

33、ers the requirements for designing the sampling system components. Clause 7 describes the requirements of an acceptable quality assurance program specific for air sampling. In addition, the following annexes provide information of use to sampling program and system designers: Annex A provides techni

34、ques for measurement of flowrate through a stack or duct. Annex B outlines modeling of particle losses in transport systems and presents an example of using a computer code to estimate aerosol penetration through a transport system. Annex C presents special considerations for the extraction, transpo

35、rt, and sampling of radioiodine. Annex D illustrates criteria for the selection of filters for collecting airborne radioactive particles. Annex E describes the statistical basis of evaluating effluent sampling errors and uncertainty. Annex F summarizes when to conduct sampling system performance ver

36、ification and how this may be accomplished. Annex G explains transuranic aerosol particulate characteristics and the implications for extractive sampling in nuclear facility effluents. Annex H discusses tritium sampling and detection. This standard does not cover: a. the selection of sampling locati

37、ons in work areas or containments; ANSI/HPS N13.1-1999 2 b. selection of specific instrumentation for sample collection or on-line monitoring of collected samples; c. the analysis of collected samples; d. the reporting and interpreting results. 1 Scope This standard sets forth guidelines and perform

38、ance-based criteria for the design and use of systems for sampling the releases of airborne radioactive substances from the ducts and stacks of nuclear facilities. 1.1 Relationship to other standards The potential applications of this standard are diverse, and consequently it is inappropriate to inc

39、orporate the many laws, regulations, and guidelines of governmental bodies that have an interest in the measurement of radioactive air emissions. It is incumbent on the user to be familiar with the applicable regulations. 1.2 Application of this standard The requirements presented in this standard a

40、re aimed at sampling programs conducted for regu-latory compliance. These requirements may not be universally applicable to all sampling programs, especially those with more limited objectives such as process control. When designing systems with objectives other than regulatory compliance, the desig

41、ner should exercise professional judgement in the application of these requirements and should explicitly document the sampling objectives and the reasons for any exceptions to the requirements of this standard. 2 Normative references The following standards and U.S. Environmental Protection Agency

42、(EPA) test methods contain provisions that, through reference in this text, constitute provisions of this American National Standard. At the time of publication, the editions indicated were valid. All standards and EPA methods are subject to revision, and parties to agreements based on this American

43、 National Standard are encouraged to investigate the implications of the most recent editions of the standards and methods indicated below. ANSI N13.2-1969 (Reaffirmed 1982), Administrative Practices in Radiation Monitoring, outlines administrative practices of a program for monitoring ionizing radi

44、ation, including gaseous effluents. ANSI N42.18-1980 (Reaffirmed 1991) Specification and Performance of On-Site Instrumentation for Continuously Monitoring Radioactivity in Effluents, provides performance criteria for instrumentation used for monitoring radioactivity in liquid and airborne effluent

45、streams. How effluent stream characteristics, operating environment factors, and standards and regulations affect the selection of instrumentation for effluent monitoring systems are briefly discussed. Dynamic range; sensitivity; accuracy; precision, physical, mechanical, and electrical requirements

46、; and detection capability are also addressed. Testing procedures are not covered. ANSI N320 (1979), Performance Specifications for Reactor Emergency Radiological Monitoring Instrumentation, addresses the essential performance parameters of monitoring instruments used during an accident event at rea

47、ctors. The instrument operating environment, operational characteristics, and lower and upper detection limits are also addressed. The general instrument locations inside the reactor plant, at release points, and in the plant environs are addressed. 40 CFR 60, Appendix A, Method 1, Sample and Veloci

48、ty Traverses for Stationary Sources, provides criteria for the number of points and conditions for velocity measurements. 40 CFR 60, Appendix A, Method 2, Determination of Stack Gas Velocity and Volumetric Flowrate (Type S Pitot Tube), provides a methodology for flow measurements. 40 CFR 60, Appendi

49、x A, Method 2C, Determination of Stack Gas Velocity and Volumetric Flowrate in Small Stacks or Ducts (Standard Pitot Tube), describes flow ANSI/HPS N13.1-1999 3 characterization methodology for stacks and ducts less than 300 mm in diameter. 3 Glossary and nomenclature A system for sampling radionuclides from a stack or duct can consist of several general components, as shown in figures 1a and 1b. A nozzle, placed at a location where a representative sample can be extracted, is used to remove the sample from the bulk flow stream. The transport line generally consist