1、American National Standardfor Methods of Nuclear Material Control Nondestructive Assay Program Nondestructive Assay Measurementsof Nuclear Material Holdup:General ProvisionsANSI N15.56-2014An INMM Sponsored DocumentANSIN15.56-2014ANSIN15.56-2014American National Standardfor Methods of Nuclear Materi
2、al Control Nondestructive Assay Program Nondestructive Assay Measurementsof Nuclear Material Holdup:General ProvisionsSecretariatInstitute of Nuclear Materials ManagementApproved October 20, 2014American National Standards Institute, Inc.Approval of an American National Standard requires review by A
3、NSI that therequirements for due process, consensus, and other criteria for approval havebeen met by the standards developer.Consensus is established when, in the judgement of the ANSI Board ofStandards Review, substantial agreement has been reached by directly andmaterially affected interests. Subs
4、tantial agreement means much more thana simple majority, but not necessarily unanimity. Consensus requires that allviews and objections be considered, and that a concerted effort be madetowards their resolution.The use of American National Standards is completely voluntary; theirexistence does not i
5、n any respect preclude anyone, whether he has approvedthe standards or not, from manufacturing, marketing, purchasing, or usingproducts, processes, or procedures not conforming to the standards.The American National Standards Institute does not develop standards andwill in no circumstances give an i
6、nterpretation of any American NationalStandard. Moreover, no person shall have the right or authority to issue aninterpretation of an American National Standard in the name of the AmericanNational Standards Institute. Requests for interpretations should beaddressed to the secretariat or sponsor whos
7、e name appears on the titlepage of this standard.CAUTION NOTICE: This American National Standard may be revised orwithdrawn at any time. The procedures of the American National StandardsInstitute require that action be taken periodically to reaffirm, revise, orwithdraw this standard. Purchasers of A
8、merican National Standards mayreceive current information on all standards by calling or writing the AmericanNational Standards Institute.American National StandardPublished byAmerican National Standards Institute, Inc.25 West 43rd Street, New York, NY 10036Copyright 2014 by Institute of Nuclear Mat
9、erials Management (INMM)All rights reserved.No part of this publication may be reproduced in anyform, in an electronic retrieval system or otherwise,without prior written permission of INMM, 111 Deer Lake Road,Suite 100, Deerfield, IL 60015.Printed in the United States of AmericaiContentsPageForewor
10、d ii0 Introduction. 11 Scope and purpose 12 References . 23 Definitions. 24 Administrative aspects of determining results for in situ measurements 45 Data generation and reporting 9AnnexesA Bibliography 12B Example in situ holdup NDA DQO Comparable Process form. 15iiForeword (This foreword is not pa
11、rt of American National Standard ANSI N15.56-2014.)This standard was developed under the procedures of the American National Stan-dards Institute by Accredited Standards Committee N15 on Methods of Nuclear Ma-terial Control. The secretariat of N15 is held by the Institute of Nuclear MaterialsManagem
12、ent (INMM). Committee N15 has the following scope:Standards for the protection, control, and accounting of special nuclear materials inall phases of the nuclear fuel cycle, including analytical procedures where necessaryand special to this purpose, except that physical protection of special nuclear
13、materi-als within a nuclear power plant is not included.This standard defines administrative practices for generating and reporting of nonde-structive assay (NDA) data regarding holdup deposits. It provides guidance on proce-dures, definition of terms, definition of data quality objectives, vocabula
14、ry,recordkeeping, application of techniques, calculation, reporting of values, and uncer-tainties so that some consistency of use can be achieved by as large a community ofstakeholders as practicable.Suggestions for improvement of the standard will be welcome. They should be sentto the Institute of
15、Nuclear Materials Management, 111 Deer Lake Road, Suite 100,Deerfield, IL 60015. (Additional information about the INMM may be found at http:/www.inmm.org.)This standard was prepared by Committee N15 following ANSI requirements for dueprocess and for obtaining consensus. N15 Committee approval of th
16、e standard doesnot necessarily imply that all committee members voted for its approval. At the time itapproved this standard, the N15 Committee had the following members:Melanie May, Chair(U.S. Department of Energy)Lynne Preston, Vice-Chair(U.S. Department of Energy)Steven Ward, Secretary(Entergy Op
17、erations, Inc.)Organization Represented Name of RepresentativeAmerican Nuclear Society (ANS) . Ronald KniefAmerican Society for Quality (ASQ) . Chuck MoseleyAmerican Society for Testing and Materials (ASTM) Usha Narayanan American Society of Industrial Security (ASIS) Robert D. HulshouserAREVA-NP .
18、Dan NossBabcock now used by the Society as its complete name. 1Available from the ANSI Electronic Standards Store (ESS) at www.webstore.ansi.org . 2Available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959 (http:/www.astm.org/). ANSI N15.56-2014 3 3.2
19、audit: An examination of current activities to assure that they are in compliance with program policies and procedures. 3.3 Data Quality Objective (DQO): An agreement between the measurement organization and its customer regarding the quality of the data expected and the type of quality programs in
20、place to assure the quality of the measurement data. (See 4.1.1.6 for more details.) 3.4 Generalized-Geometry Holdup (GGH): This holdup measurement technique simplifies analysis by approximating the geometry of a holdup deposit as a point, line, or area source. 3.5 holdup: The residual nuclear mater
21、ial remaining in process equipment and facilities 1. 3.6 in situ measurements: A method of data collection or manipulation of a sample in its original position, without exposure to an external environment. 3.7 ISO: The acronym for the International Organization for Standardization. 3.8 item: Materia
22、l potentially containing a radioisotope to be measured 1. 3.9 matrix: The material that comprises the bulk of an item, except for the radionuclide(s) of interest and the container 1.3.10 method validation: As used in this standard, validation provides documented, objective evidence that the choice o
23、f measurement method is capable of meeting specified requirements.33.11 nuclide mapping: Determining the isotopic composition of holdup at specific locations to assess isotopic distribution and variability and to detect the presence of radionuclides that could interfere with the holdup measurement.
24、3.12 self-attenuation: The attenuation of emitted radiation by the emitting material itself, including any matrix material(s). 3.13 special nuclear material (SNM): U-233, uranium enriched in U-235, plutonium, or any combination thereof, and any other material which, pursuant to the provisions of Sec
25、tion 51 of the Atomic Energy Act of 1954, as amended, has been determined to be special nuclear material, but does not include source material; it also includes any material artificially enriched by any of the foregoing, not including source material as defined by the Atomic Energy Act, Title 42, U.
26、 S. Code, Section 2002, et seq. 3.14 system qualification: The documented process of ensuring that a specific measurement system is capable of providing reliable and consistent data of the needed quality. 3.15 Type A uncertainty: An uncertainty whose evaluation is based on any valid statistical meth
27、od for treating data 2. EXAMPLE: Calculating the standard deviation of the mean of a series of independent observations or using the method of least squares to fit a curve to data in order to estimate the parameters of the curve and their standard deviations. 3IUPAC Technical Report “Harmonized Guid
28、elines for Single-Laboratory Validation of Methods of Analysis,” Pure Appl. Chem, Vol. 74, No. 5, pp. 835-855, 2002 provides a more complete explanation of factors to be considered during method validation and system qualification. ANSI N15.56-2014 4 3.16 Type B uncertainty: An uncertainty whose eva
29、luation is based on scientific judgment using all relevant information available 2. EXAMPLE: Previous measurement data, experience with or general knowledge of the behavior of similar measurements, manufacturers specifications. 4. Administrative aspects of determining results for in situ measurement
30、s 4.1 Measurement method 4.1.1 Method selection Many interrelated factors shall be considered in choosing the method to use for in situ holdup measurements. When these factors have been thoroughly evaluated and the measurement method has been specified, all considerations affecting the choice shall
31、be documented and archived for future reference (5.1). Factors to be considered are: 4.1.1.1 Customer/Purpose of measurement This factor, in many cases, controls the approach to the measurement and the presentation of the measurement results. Measurements are performed for Materials Control and Acco
32、untability (MC process control; criticality safety; radiological protection; deactivation and decommissioning (D waste characterization; process cleanout; and combinations of these and other reasons. Each reason for the measurement might have different objectives, e.g., different uses, for the measu
33、rement uncertainty. The measurements may be quantitative, relative mapping, or both. Holdup measurements can be routine at operating facilities so relative monitoring may be applied as an alternative to absolute measurements when well below criticality safety limits. Data quality objectives and end
34、use of the measurement results should be documented prior to starting any measurements. 4.1.1.2 Materials to be measured The element(s) and isotope(s), the chemical and physical forms, and the radiation signatures likely to be present shall be considered. Measurement of uncommon actinides such as Np
35、, Cm, Am, Th, etc. could present additional measurement challenges that will need to be addressed. There is more measurement and instrumentation information available for measurements on U and Pu than there is for the less common actinides. Factors to be considered include: Radiation signature or is
36、otopic distribution Background interference Matrix Containment of measured material Intervening materials Chemical forms Densities Some measurement methods probe the nuclide of interest directly, while others use indirect radiation signatures. For example, gamma measurements usually deal with charac
37、teristic emissions from the nuclide of interest (U-235, Pu-239), whereas passive neutron-counting techniques are based on radiation from associated nuclides (U-234, Pu-240). Some parameters affect the use of certain measurement methods but not others. For example, self-shielding, container type, and
38、 high-density matrix effects often attenuate a gamma signal, while not significantly affecting a neutron measurement. On the other hand, neutron systems are sensitive ANSI N15.56-2014 5 to low z materials and chemical form due to their neutron attenuation and production differences, but these factor
39、s often do not affect gamma measurements significantly. 4.1.1.3 Physical measurement conditions Measurement conditions greatly influence the choice of detector type and data analysis methods. Facility and process equipment blueprints or drawings should be used if available, and all stakeholders shou
40、ld conduct a walk-down of the measurement site to jointly evaluate the measurement conditions for non-routine measurements. The safety and security of the measurement and the results should always be considered. Factors specific to the measurement to be considered include: Access to measurement loca
41、tion(s) Environment i.e., temperature, moisture, and dust, etc. Equipment/process configuration Size of the process equipment, including thickness and uniformity characteristics of attenuating materials Height and spacing of the process equipment and/or piping Power availability 4.1.1.4 Measurement
42、resources Numerous measurement methods exist for in situ holdup measurements 3, 4, 5, 6, 7, 8. The measurement personnel should adapt their resources to the best method to meet data quality objective requirements. Factors to be considered include: Training and experience of measurement personnel Typ
43、es and quantity of measurement equipment Time available for performing measurements and for reporting results NDA lessons learned and good practices 4.1.1.5 Constraints Constraints can take many forms both technical and nontechnical. Constraints to be considered include: Time allotted for the measur
44、ements When results are needed Operational significance Location access Funding Equipment 4.1.1.6 Data quality objectives The customer and the measurement organization should agree on the expectations for data quality, given the measurement issues noted above and the data quality requirements of the
45、 customer. This agreement can be based on the Data Quality Objective process described in EPA QA/G4 9 or on a facility specific comparable process. See Annex B for a generic blank DQO form example. This agreement shall be documented and archived for each specific task. Data quality objectives have a
46、 significant effect on measurement method selection, the accuracy and precision of resulting measurements, and the time and cost to perform measurements. Data quality objectives could include the following: ANSI N15.56-2014 6 Desired precision and accuracy Application to compliance criteria Peer rev
47、iew of method or results Measurement and personnel qualification Re-measurement program Sampling plans Relationship between data acquisition and data analysis, such as allowable time lapse and whether done by same/different personnel 4.1.1.7 Method validation Once a method has been selected, the met
48、hods fitness for purpose shall be validated, or evaluated, before it is qualified. The purpose of validation is to demonstrate, in a documented form, that the method chosen is appropriate to the needs of the end users of the data that will be produced. Validation of methods employed by measurement s
49、ystems that will be subsequently qualified may be accomplished by citing available published references and publications describing successful measurements under the expected conditions. External peer review by subject matter experts can also be used for validation of a technique or its application. If the proposed method lacks published validation for the specific data quality objectives, the user should perform measurements and testing under expected holdup measurement conditions to validate the method.4
