Regulatory Guide 5.53

Qualification,Calibration & Error Estimation Methods for Nondestructive Assay

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Issue date:	02/29/1984
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February 1984 U.S. NUCLEAR REGULATORY COMMISSION

REGULATORY GUIDE

OFFICE OF NUCLEAR REGULATORY RESEARCH

REGULATORY GUIDE 5.53 (Task SG 049-4)

QUALIFICATION, CALIBRATION, AND ERROR ESTIMATION

METHODS FOR NONDESTRUCTIVE ASSAY

A. INTRODUCTION

was reviewed and reaffirmed without modification in

1980. This guide endorses the entire standard as supple Section 70.58, "Fundamental Nuclear Material Con mented in the regulatory position.

trols," of 10 CFR Part 70, "Domestic Licensing of Special

C. REGULATORY POSITION

Nuclear Material," requires certain licensees to establish a measurement quality assurance program for material The methods, procedures, and guidance relating to the control and accounting. Specifically, paragraph 70.58(f)

requires that a program be established, maintained, and application of NDA in ANSI N15.20-1975, "Guide to followed for the maintenance of acceptable measurement Calibrating Nondestructive Assay Systems," are accept quality in terms of measurement bias and for the evalua able to the NRC staff for use in material protection tion and control of the quality of the measurement programs as supplemented by the following.

system.

1. METHOD SELECTION

Nondestructive assay (NDA) constitutes a unique measurement technology. When applied under appropriate Prior to selecting an assay method, a study should be rigorous controls, it can enhance the ability of the material made to determine the required performance for that appli control and accounting system to detect unaccounted-for cation. The specific NDA method should be selected to loss or diversion of special nuclear material (SNM) to provide results that are compatible with plant material unauthorized uses. This guide describes methods and balance requirements. Methods to enhance attainable procedures acceptable to the NRC staff for meeting the performance should be considered (e.g., container selec provisions of paragraph 70.58(f) of 10 CFR Part 70 as it tion and packaging procedures for bulk materials discussed relates to the use of nondestructive assay. in Regulatory Guide 5.11, "Nondestructive Assay of

2 Special Nuclear Material Contained in Scrap and Waste" ).

Any guidance in this document related to information

2. INSTRUMENT SPECIFICATIONS

collection activities has been cleared under 0MB Clearance No. 3150-0009.

An evaluation of each new NDA application, including

B. DISCUSSION

the proposed placement of the instrument, should be conducted prior to procurement. Studies of existing NDA

Nondestructive assay has been applied to virtually applications should be conducted periodically to evaluate every chemical or physical form of special nuclear material their performance and substantiate the basis for their encountered in contemporary reactor fuel processing. continued use. The impact of each of the measurement-to Special considerations are required to achieve high measurement sources of error encountered in practice accuracy assay results and to properly estimate the errors or anticipated should be established as a part of each of associated with NDA applications. Recognizing these these efforts.

considerations, the American National Standards Institute has developed a standard, ANSI N15.20-1975, "Guide to Calibrating Nondestructive Assay Systems."' This standard The substantial number of changes in this revision has made it impractical to indicate the changes with lines in the margin.

2

1 A proposed revision to this guide has been issued for comment Copies may be obtained from the American National Standards Institute, 1430 Broadway, New York, New York 10018. as Task SG 043-4.

USNRC REGULATORY GUIDES Comments should be sent to the Secretary of the Commission, U.S. Nuclear Regulatory Commission, Washington, D.C. 20555, Attention: Docketing and Service Branch.

Regulatory Guides are issued to describe and make available to the public methods acceptable to the NRC staff of implementing The guides are issued in the following ten broad divisions:

specific parts of the Commission's regulations, to delineate tech niques used by the staff in evaluating specific problems or postu 1. Power Reactors 6. Products lated accidents or to provide guidance to applicants. Regulatory 2. Research and Test Reactors 7. Transportation Guides are noi substitutes for regulations, and compliance with 3. Fuels and Materials Facilities 8. Occupational Health them is not required. Methods and solutions different from those set 4. Environmental and Siting 9. Antitrust and Financial Review out in the guides will be acceptable if they provide a basis for the 5. Materials and Plant Protection 10. General findings requisite. to the issuance or continuance of a permit or license by the Commission.

Copies of issued guides may be purchased at thecurrent Government This guide was issued after consideration of comments received from Printing Office price. A subscription service for future guides in spe the public. Comments and suggestions for improvements in these cific divisions is available through the Government Printing Office.

Information on the subscription service and current GPO prices may guides are encouraged at all times, and guides will be revised, as be obtained by writing the U.S. Nuclear Regulatory Commission, appropriate, to accommodate comments and to reflect new informa tion or experience. Washington, D.C. 20555, Attention: Publications Sales Manager.

A decision should be made to reduce each potentially ically test the performance stability of the instrument.

significant source of error through (1) appropriate instrument Each working standard should contain a different amount design considerations, (2) operational controls, or (3) supple of the species of SNM to be assayed. Current licensing mentary measurements made to establish bias corrections review criteria require the use of four working standards.

(see also Reference 1). Instrument procurement specifica On a rotating basis, one or two of these standards are used tions and operational instructions should be developed and to check the system each day.

followed to reflect each error-reduction decision.

It should be noted that, in general, a working standard To minimize operator-related errors and to promote uni need not be fabricated from the same type of material form measurement practices, NDA instruments used for fixed being assayed. Even a material from a different radioactive station operations should be automated to control (1) data species may be acceptable if carefully chosen and pre acquisition and analysis, (2) diagnostic testing of instrument pared. The essential requirements for a working standard performance stability and calibration validity, and (3) calcu are that (1) the radiation characteristics of the working stan lation of associated error estimates. It is recognized that, dard are sufficiently stable to ensure that fluctuations in for some less complicated NDA measurements, consistency instrument response during measurement control can con of operation may be achieved through the implementation fidently be attributed to aberrations in instrument param of carefully written and tested standard operating procedures. eters rather than to variations in source characteristics and

(2) the working standard induces a response in the NDA

Instruments should be tested to ensure that they meet instrument that is characteristic of the expected response to procurement specifications prior to calibration. real assay material. The most convenient means of achieving this "representative response" characteristic is to use mate

3. OPERATORS rial similar to the material that will be assayed.

Adequate operator qualification requirements are A study should be made to determine the frequency crucial to proper calibration and effective measurement with which the working standards are to be measured. If control of an NDA instrument. The qualification require there is some instability, a working standard should be ments should include a general knowledge of the assay measured before and after each assay of an unknown technique being used and an understanding of the typical item, and the calibration should be normalized to reflect behavior and the limitations of the instrument and the the average of the before-assay and after-assay tests. In technique. A knowledge of the external factors to which general, excessive instabilities should not be tolerated;

the measurement technique is sensitive (factors such as they should be remedied by frequent recalibration. If matrix composition, background, material forms, and instabilities persist, an alternative technique, an alternative container type) is also necessary. Only then can proper instrument, or another measurement environment should standards be chosen for calibration and measurement be sought. In any case, a working standard should be control data be interpreted effectively. measured a minimum of twice per shift, once at the beginning of the shift and again at some random time If the operators have only a general knowledge of during the shift.

external factors, the NDA measurement program must be overseen by a director with a detailed knowledge of all As a general principle, working standards should be run related factors. Only qualified operators should be permit with a frequency directly proportional to the frequency ted to make SNM assays. of measurements (i.e., increase as the measurement frequency increases and decrease as the measurement

4. STABILITY TESTING frequency decreases). Also, the quantity of SNM in the standards measurements should closely follow the quanti A preventive maintenance program should be devised ties of SNM being measured (i.e., the frequency of high and implemented to ensure the long-term stability and SNM-content working standards measurements increases reliability of each instrument. as the frequency of assays of like items increases). These procedures provide a useful estimate of the bias when As part of an ongoing Iprogram of measurement control, determined at the end of the inventory period. In addition, more working standards should be fabricated to period working standards should be run frequently enough for

3 Working standards are used to check the performance each measurement system so that no one system could of an contribute excessively to the inventory difference (ID) by NDA instrument. They should be nominally representative of the items to be assayed. They should be fabricated and handled to being out of control for an extended period. A minimum ensure their internal integrity so that deviations in the measured response of the assay system can be attributed to the instrument. of 16 control measurements should be made per material As stated in ANSI Nl5.20-1975, working standards built to meet these requirements are not acceptable as calibration standards. balance period. Assuming two systems having equal material Calibration standards are defined in ANSI N 15.20-1975 as "physically flows in SNM quantity and number of items, the system and chemically similar to the items to be assayed, for which the mass of the nuclide(s) of interest and all properties to which the with the greater uncertainty per measurement should run measurement technique is sensitive are known." Calibrationstandards more working standards to reduce its potential impact on can be used as working standards, but working standards cannot be used as calibration standards. When calibration standards meet the ID.

the requirements for working standards, licensees may elect to maintain only calibration standards. However, calibration standards may deteriorate through extensive use or may be prohibitively Each response to a working standard should be compared expensive for stability monitoring purposes. to the previous calibration data as well as to the mean value

5.53-2

of previous measurements of that working standard (under furnace liner bricks, contaminated tools, or machine parts),

the same calibration) that were accumulated during the the calibration relationship should be determined by a preceding material balance period. The difference should be suitable method such as a least-squares fit to an appropriate plotted on a control chart. Control chart limits should be function as described in ANSI N15.20-1975. The graphical established at 0.05 and 0.001 levels of significance. When calibration method is acceptable only for miscellaneous ever control data exceed the 0.05 control limits, the test categories of material that contain a total of no more than should be repeated. Whenever the control data exceed the 0.1 effective kilograms of SNM in each category during a

0.001 control limits, normal assay operations should cease. material balance period. The combined contribution from Normal operations should not resume until the out-of all assays calibrated through the graphical method should control performance has been remedied and the instrumefit be less than 10 percent of the total plant standard error has been recalibrated. (estimator) of inventory difference (SEID).

The control chart of the working standard responses 6. CALIBRATION STANDARDS

should be examined at frequent intervals to detect indica tions of drift, which should be compensated. The frequency Calibration standards should be obtained to serve as the for such examinations should be determined by the operat basis for the initial calibration of each instrument for each ing characteristics of each instrument. The minimum separate measurement technique or category of material.

frequency for examining the control chart of a regularly The number of standards in each set should be greater used instrument for indications of drift should be once per than the number of free parameters in the calibration week. function for that set. It is recognized that, in some special cases, one set of calibration standards may suffice for more

5. CALIBRATION than one measurement technique or material category with proper analysis of the raw calibration data. Furthermore, if Calibration of NDA instruments should be accomplished the NDA instrument is intended for use over a very narrow by measuring the response to calibration standards as range of SNM loadings, a more restricted range of SNM

described in ANSI N15.20-1975. The nuclear material content in the calibration standards (confined to bracket content of these standards should be characterized through the expected assay range) would prove adequate. The established assay procedures (e.g., chemical assays) that are calibration standards should be completely characterized, calibrated relative to national standards or nationally including the mass and isotopic composition of the species accepted measurement systems. The calibration standards of SNM to be assayed and all physical or chemical variables should represent the unknown items in all physical and to which the response of the instrument is sensitive.

chemical characteristics that affect the response of the instrument. Calibration data should be obtained by averag In general, the mass of SNM contained in the standards ing the responses from repeated measurements of the should extend over the range of loadings encountered in calibration standards and should be corrected to remove routine assays. This is especially true for NDA instruments observed nonrandom variations. whose responses are not linear functions of SNM content (e.g., some neutron-based NDA instruments). However, if Recalibration of an instrument is required following repair the assay response (after application of appropriate correc or replacement of parts if measurement of one or more tions) is known to be highly linear and to have zero offset working standards shows the instrument response to have (i.e., zero response for zero SNM content), it may be more changed. In addition, the calibration should be checked advantageous to avoid using standards with low loading, following a power outage or any unusual mechanical or where calibration precision would suffer because of low electrical shock to the system. Recalibration data are also count rates. In such a case, calibration in the upper half of required if the characteristics of the items to be assayed the range of expected SNM loadings, combined with change to the extent that previous calibration standards no the constraint of zero response for zero loading, can produce longer adequately represent the unknown items. a higher precision calibration than a least-squares fitting of measured responses to the standard over the full range of Criteria for segregating and packaging different forms of expected loadings, including values at low concentrations of SNM should be developed and implemented. Each material SNM. If such a calibration procedure is used, careful initial category should be established to enhance assay perform establishment of the zero offset and instrument linearity ance, consistent with safety requirements and subsequent followed by occasional verification of both assumptions processing needs. Guidance for material categorization is strongly recommended. Such verification could be is provided in Regulatory Guides 5.11, "Nondestructive accomplished by an occasional extended measurement of a Assay of Special Nuclear Material Contained in Scrap and low-loading standard.

Waste," 2 and 5.34, "Nondestructive Assay for Plutonium in Scrap Material by Spontaneous Fission Detection."

4 Unless isotopic composition is being measured, the isotopic composition of the material used in all calibration For all categories of materials to be assayed, with the standards should be similar to the isotopic composition of exception of small-content miscellaneous categories (e.g., the material being assayed. This is especially important for

4A proposed revision to this guide has been issued for comment SThe term "effective kilogram" is defined in paragraph 70.4(t)

as Task SG 046-4. of 10 CFR Part 70.

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assays employing passive neutron coincidence counting or 7.2 Analytical Estimation Through the Calibration calorimetry. When the isotopic composition changes so that Relationship the response per gram of SNM differs by 10 percent or more from the value of the calibration standards, the When the calibration standards can be shown to represent material should be identified as a new material category. adequately the unknown items, the bias associated with the The NDA system should be recalibrated for that category NDA of an inventory of items can be estimated through the using new calibration standards made up using the new calibration relationship as demonstrated in ANSI N15.20

isotopic composition. When the change in response per 1975. The calibration standards should be fabricated from gram is less than 10 percent, a bias correction should be different batches of material. The uncertainty associated determined and applied to the assay data. with the content of SNM elements and response-related isotopes contained in each calibration standard should be The uncertainty in the bias correction should be deter based on an extensive characterization as described in mined and accounted for in estimating the total assay ANSI N15.20-1975. The uncertainty associated with the, uncertainty. Appropriate error propagation procedures are contained mass of the response-related isotopes should be described in Regulatory Guide 5.18, "Limit of Error included in the calibration as described in the standard.

Concepts and Principles of Calculation in Nuclear Materials Further, the element uncertainty should be factored into Control." the estimated total assay uncertainty.

When the response is sensitive to ingrowth or decay of a Using this procedure, it is necessary to periodically daughter product, the procedures described in the preced ensure that the calibration standards adequately represent ing paragraphs are appropriate and should be applied. the unknown items. This can be accomplished by isolating and characterizing the extraneous interference factors Once fabricated, the calibration standards should be that affect the response of the instrument. Typically, this handled with extreme care to attempt to ensure that the separation and characterization is most easily accomplished distribution of contents remains fixed. It should be noted when the items are either finished fuel items or uniform that solution standards lose their integrity over time because containers of feed or intermediate product material.

of evaporation and diffusion (Ref. 2) and radiolysis (Ref. 3).

Calibration standards prepared by the mixing of different To ensure that the calibration standards continue to powders or densities tend to stratify or segregate. The adequately represent unknown items, key parameters 6 that containers should be tumbled periodically to reblend affect the observed response (i.e., item-to-item variations)

the constituents. Calibration standards should be used only should be monitored through separate tests. Measurements when developing the initial calibration or when recalibrat of the key parameters should be compiled and analyzed at ing the instrument following a repair or power outage. least twice a month to catch any large instrument drift. For Working standards should be used to test the continued more timely measurement control, a superior approach stability of the instrument (see footnote 3). would be to perform such analyses on a continuing basis and repeat measurements of unknowns where standards The degree of effort that should be expended in fabricat exceed control limits. This latter approach minimizes the ing the calibration standards depends on the method used backfitting of measurement data and provides a timely to estimate the assay uncertainty, as described in the next basis for measurement control.

section.

When the mean value of a parameter shifts from its

7. METHODS FOR ESTIMATING UNCERTAINTY previously established value, the impact of the shift on the response of the assay instrument should be measured Instrument errors associated with NDA should be through an appropriate experiment or calculation (Ref. 4).

estimated periodically by means of replicate assays as An appropriate bias correction should be determined and described in ANSI N15.20-1975. applied to all items that were assayed after the best estimate of when the parameter changed. The uncertainty in that Three methods are acceptable to estimate the uncertain bias estimate should be combined with the uncertainty in ties associated with calibrations and bias corrections for the assay values as predicted through the calibration function NDA. The first two procedures, graphical estimation and to estimate the total assay uncertainty.

analytical estimation through the calibration relationship, are detailed in ANSI N15.20-1975. The third procedure, The uncertainty due to a bias correction may significantly comparative evaluation, is not described in the standard. increase the standard error of the assay. In severe cases, the effect may increase the SEID above the level acceptable for the total plant. In such cases, new calibration standards

7.1 Graphical Estimation should be obtained and the assay system should be recali brated.

Use of the graphical error estimation technique should result in a conservative error estimate that is acceptable for 6 See Section 5.4 of ANSI N15.20-1975. See Regulatory miscellaneous unusual assay categories, as described in Posi tion 6 of this guide for provisions to include the effects of changing Regulatory Position 5 of this guide. isotopic compositions.

5.53-4

As a further check on the continued validity of the cali 2. For plutonium-bearing items only, each item can be bration standards, a program to periodically introduce new assayed through calorimetric procedures (see Reference 5).

calibration standards should be implemented. The rate of Large items should be subdivided into smaller containers.

replacement of standards with fresh material depends on Each small container should be assayed calorimetrically.

the intrinsic durability and stability of the standard in Samples should be taken from at least three of the smaller question. Some solution standards lose their calibrated containers. The samples should be measured by micro concentration values in a matter of days or weeks. On the calorimetry and then assayed through highly accurate other hand, standard fuel rods are much more durable and elemental and isotopic procedures that, in turn, are calibrated may last indefinitely with careful handling. In any case, relative to national standards or nationally accepted measure calibration standards should be replaced with new standards ment systems (Ref. 6). The isotopic measurement data at a rate sufficiently above their failure rate to ensure should be examined for evidence of nonhomogeneous continued high quality in the instrument calibration. isotopic content. Isotopically nonhomogeneous materials should be blended and reanalyze

d. On the basis of the

7.3 Comparative Evaluation average grams of plutonium per watt of the samples meas ured by microcalorimetry, the total amount of plutonium The procedure described in this section is not included in each of the smaller containers should be determined. The in ANSI N15.20-1975 but is appropriate for determining the total plutonium content of the items selected for compar validity of the calibration of NDA instruments. ison is then estimated as the combined contents of the smaller containers.

When two measurement methods are used for each of a series of items and one of the methods is considerably more For the first full material balance period during the accurate than the other, corresponding measurements can initial implementation of this guide, two items from each be usefully compared. The comparison can be used to category of assay items should be randomly selected each establish an estimate of bias between the measurement week for a check of the validity of the instrument cali methods. The comparison can also be used to estimate the bration. Following this initial implementation period, total uncertainty associated with the less accurate measure licensees may reduce the verification measurement frequency

,ment method. to two items per month per category. When fewer than 100

new items of a given category are created per week, at To determine the uncertainty associated with the NDA least two of the item-comparison verification measurements of an inventory of items using this method, unknown items should be made per material balance period per category should be randomly selected for comparative measurements. through the procedures described above. In such cases, to The SNM content of the items selected should span the provide an adequate data base to update the uncertainty range of contents normally encountered, subject to the estimates for NDA, licensees may pool the verification data qualification pointed out in Regulatory Position 6. Random provided the measurements are in statistical control, i.e.,

error should be estimated through replicate analyses. To when repeated samples from the portion of the measure estimate the remaining contributions to the total assay ment system under test behave as random samples from a uncertainty, each item should be repeatedly assayed to stable probability distribution. Under such conditions, data reduce the random assay error to less than 10 percent of sets may be combined provided the parameters based on the estimated or previously established total uncertainty. the current set of data and the previous set of data are not Then, to determine the SNM content of each item selected significantly different on the basis of acceptable statistical for comparative evaluation, one of the following procedures tests.

should be employed:

As an alternative to this selection criterion, licensees

1. Each item should be completely dissolved, independ may elect the latter frequency for a specific category when ently, and the resulting solution should be analyzed by it can be demonstrated that the contribution to the SEID

high-accuracy elemental and isotopic assay procedures, from that category is less than 100 grams in any mate which in turn are calibrated relative to national standards rial balance period.

or nationally accepted measurement systems. It should be recognized that dissolution residues may be present in such At the close of the reporting period, differences between a procedure. These residues should also be assayed for a assay values and verification values should be recorded and complete analysis. Items composed of an aggregate of tested for outliers. Methods for detecting outliers are similar units, e.g., fuel rods containing discrete pellets, described in ANSI/ASTM E178-80, "Practice for Dealing with should be opened and the contained units should be weighed, Outlying Observations." 7 See also Regulatory Guide 5.36, pulverized, blended, and sampled for assay through appro "Recommended Practice for Dealing with Outlying Observa priate high-accuracy elemental and isotopic assay proce tions," for further details.

dures. The emptied container should be examined for indications of residual accumulations and cleaned, leached,

7 or assayed nondestructively to determine the residual SNM Copies may be obtained from the American Society for Testing content. and Materials, 1916 Race Street, Philadelphia, Pennsylvania 19103.

5.53-5

A straight line with a nonzero intercept should be fitted that may influence the response of the assay system should to the nondestructive assay vs. verification measurement be investigated. The investigation should also address the data as described in ANSI N15.20-1975. The slope and comparative measurement method, including sampling, intercept should be jointly tested for one and zero, respec sample handling, analytical procedures, interference com tively, using the "F" ratio at the 5 percent significance level pensation, and calibration validity. Results from the investi (Ref. 7). If this result is significant, separate tests on the I

gation, if they show the NDA system to have been incorrectly slope equal to one and the intercept equal to zero should be calibrated, should be employed to recalibrate the instrument made to determine the presence of either proportional or for the forthcoming material balance period. Conversely, constant bias or both. When bias is indicated, the assay when the source of bias can be attributed to errors in the results during the preceeding operating period should be comparative measurements, bias corrections should not be corrected. The variance associated with the bias corrections made to the items assayed by NDA. Results from such should be estimated by the standard error of estimate of investigations should be documented, and the documents the verification line. This variance must be included in the should be maintained in accordance with Regulatory estimate of the variance of an assay result as described in Position 8 of this guide.

ANSI N15.20-1975.

8. RECORDS RETENTION

Whenever a bias exceeding 50 percent of its estimated uncertainty is indicated, its cause should be investigated. All records generated in connection with the activities This investigation should include a review of the assump discussed in this guide, including control charts, should be tions factored into the NDA system's calibration. In partic retained for a period of 5 years, as specified in para ular, instrument stability and the stability of parameters graph 70.5 1(e)(4)(iii) of 10 CFR Part 70.

5.53-6

REFERENCES

4. R. A. Forster, D. B. Smith, and H. 0. Menlove, "Error

1. T. E. Shea, "Reduction, Control, and Estimation of Analysis of a Cf-252 Fuel-Rod-Assay System," Los Nondestructive Assay Errors," Nuclear MaterialsManage Alamos Scientific Laboratory, LA-5317, 1974.

ment, Vol III, No. 3, 1974.

5. U.S. Nuclear Regulatory Commission, "Calorimetric

2. G. J. Curtis, J. E. Rein, and S. S. Yamamura, "'Compara Assay for Plutonium," NUREG-0228, 1977.

tive Study of Different Methods of Packaging Liquid Reagents," Analytical Chemistry, Vol. 45, No. 6, p. 996,

6. F. S. Stephens et al., "Methods for the Accountability

1973.

of Plutonium Dioxide," U.S. Nuclear Regulatory Com mission, WASH-1335, 1975.

3. J. R. Weiss and E. E. Pietri, "Calculation of Hydrogen Generation from Pu-Induced Alpha Radiolysis of Nitric,

7. F. A. Graybill, An Introduction to Linear Statistical Sulfuric, and Perchloric Acids," Radiation Effects, Vol. Models, McGraw-Hill, New York, Vol. I, p. 128, 1961.

19, p. 191, 1973.

5.53-7

BIBLIOGRAPHY

Alvar, K., H. Lukens, and N. Lurie, "Standard Containers This book provides a complete discussion of for SNM Storage, Transfer, and Measurement," U.S. Nu statistical procedures and describes a variety of clear Regulatory Commission, NUREG/CR-1847, 1980. statistical tests of experimental data. Examples are provided.

This report details the variations of container properties (especially wall thicknesses) and their effects on NDA measurements. A candidate Reilly, T. D., and M. L. Evans, "Measurement Reliability list of standard containers, each sufficiently for Nuclear Material Assay," Nuclear Materials Manage uniform to cause less than 0.2 percent variation ment, Vol. VI, No. 2, 1977.

in assay results, is given, along with comments on the value and impact of container standardization. This paper provides an overview of experience in nuclear material assay by analytical chemistry, Brouns, R. J., F. P. Roberts, and U. L. Upson, "Considera calorimetry, and nondestructive assay. Ranges tions for Sampling Nuclear Materials for SNM Accounting of accuracy and precision obtained in the assay Measurements," U.S. Nuclear Regulatory Commission, of nuclear material are given.

NUREG/CR-0087, 1978.

This report presents principles and guidelines for Sher, R., and S. Untermeyer, The Detection of Fissionable sampling nuclear materials to measure chemical Materials by Nondestructive Means, American Nuclear and isotopic content of the material. Develop Society Monograph, 1980.

ment of sampling plans and procedures that maintain random and systematic errors of This book contains a helpful overview of a wide sampling within acceptable limits for SNM variety of nondestructive assay techniques for accounting purposes are emphasized. special nuclear material. In addition, it contains a rather extensive discussion of error estimation Cooper, B. E., Statistics for Experimentalists, Pergamon and measurement control techniques, as well as a Press, New York, 1969. presentation on measurement statistics.

h

5.53-8

VALUE/IMPACT STATEMENT

1. PROPOSED ACTION 1.3.4 Public

1.1 Description No impact on the public can be foreseen.

Licensees authorized to possess at any one time more 1.4 Decision than one effective kilogram of special nuclear material (SNM) are required in paragraph 70.58(f) of 10 CFR Part 70 The guide should be revised to reflect the affirmation of to establish, maintain, and follow a program for the main ANSI N15.20-1975 in 1980 and to make it more consistent tenance of acceptable measurement quality in terms of with current usage.

measurement bias and for the evaluation and control of the quality of the measurement syste

2. TECHNICAL APPROACH

This guide describes methods and procedures acceptable Not applicable.

to the NRC staff for meeting the provisions of para graph 70.58(f) of 10 CFR Part 70 for nondestructive assay

3. PROCEDURAL APPROACH

(NDA) systems.

Of the procedural alternatives considered, revision of the The proposed action would revise the guide, which is existing regulatory guide was selected as the most advanta still basically sound. geous and cost effective.

1.2 Need 4. STATUTORY CONSIDERATIONS

The regulatory guide endorses ANSI N15.20-1975, 4.1 NRC Authority

"Guide to Calibrating Nondestructive Assay Systems."

This standard was reaffirmed without modification in 1980 Authority for the proposed action is derived from the and the regulatory guide should be revised to indicate this. Atomic Energy Act of 1954, as amended, and the Energy Further, revisions are needed in some sections to make the Reorganization Act of 1974, as amended, and implemented guide clearer and more consistent with current thinking. through the Commission's regulations, in particular § 70.51 of 10 CFR Part 70.

This proposed action is needed to bring Regulatory Guide 5.53 up to date. 4.2 Need for NEPA Assessment

1.3 Value/Impact The proposed action is not a major action that may significantly affect the quality of the human environment

1.3.1 NRC and does not require an environmental impact statement.

The regulatory positions will be brought up to date.

S. RELATIONSHIP TO OTHER EXISTING OR

1.3.2 Other Government Agencies PROPOSED REGULATIONS OR POLICIES

Not applicable. The proposed action is one of a series of revisions of existing regulatory guides on nondestructive assay techniques.

1.3.3 Industry

6. SUMMARY AND CONCLUSIONS

Since industry is already applying the methods and procedures discussed in the guide, updating these should A revised guide should be prepared to bring Regulatory have no adverse impact. Guide 5.53 up to date.

5.53-9

UNITED STATES FIRST CLASS MAIL

POSTAGE & FEES PAID

NUCLEAR REGULATORY COMMISSION USNRC

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WASHINGTON, D.C. 20555 PERMIT No OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE, $300