Acceptable Standard Format 

and Content for the Material 

Control and Accounting 

Plan Required for Strategic 

Special Nuclear Material

Draft Report for Comment

Office of Nuclear Material Safety and Safeguards

NUREG-1280

Revision 2
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Legally binding regulatory requirements are stated only 

in laws; NRC regulations; licenses, including technical 

specifications; or orders, not in NUREG-series 

publications. The views expressed in contractorprepared publications in this series are not necessarily 

those of the NRC.

The NUREG series comprises (1) technical and 

administrative reports and books prepared by the staff 

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XXXX), (2) proceedings of conferences (NUREG/CP–

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(NUREG/BR–XXXX), and (5) compilations of legal 

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under Section 2.206 of NRC’s regulations (NUREG–

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DISCLAIMER: This report was prepared as an account 

of work sponsored by an agency of the U.S. 

Government. Neither the U.S. Government nor any 

agency thereof, nor any employee, makes any warranty, 

expressed or implied, or assumes any legal liability or 

responsibility for any third party’s use, or the results of 

such use, of any information, apparatus, product, or 

process disclosed in this publication, or represents that 

its use by such third party would not infringe privately 

owned rights.
Acceptable Standard Format 

and Content for the Material 

Control and Accounting 

Plan Required for Strategic 

Special Nuclear Material

Draft Report for Comment

Manuscript Completed: June 2013 

Date Published: September 2013

Office of Nuclear Material Safety and Safeguards

NUREG-1280

Revision 2
COMMENTS ON DRAFT REPORT

Any interested party may submit comments on this report for consideration by the NRC staff. 

Comments may be accompanied by additional relevant information or supporting data. Please 

specify the report number NUREG-1280 in your comments, and send them by the end of the 

comment period specified in the Federal Register notice announcing the availability of this 

report. 

Addresses: You may submit comments by any one of the following methods. Please include 

Docket ID NRC-2013-0195 in the subject line of your comments. Comments submitted in 

writing or in electronic form will be posted on the NRC website and on the Federal rulemaking 

website http://www.regulations.gov. 

Federal Rulemaking Website: Go to http://www.regulations.gov and search for documents 

filed under Docket ID NRC-2013-0195. Address questions about NRC dockets to Carol 

Gallagher at 301-287-3422 or by e-mail at Carol.Gallagher@nrc.gov.

Mail comments to: Cindy Bladey, Chief, Rules, Announcements, and Directives Branch

(RADB), Division of Administrative Services, Office of Administration, Mail Stop: 3WFN-06-A44, 

U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001.

For any questions about the material in this report, please contact: Tom Pham, Senior 

Safeguards Analyst, at 301-287-9132 or by e-mail at Tom.Pham@nrc.gov.

Please be aware that any comments that you submit to the NRC will be considered a public 

record and entered into the Agencywide Documents Access and Management System 

(ADAMS). Do not provide information you would not want to be publicly available.
iii NUREG-1280, Revision 2

ABSTRACT

This document provides a revised structure for NUREG-1280, Revision 1, issued March 1995, 

which specifies information that the licensee or applicant should provide in its material control 

and accounting (MC&A) plan, formerly the fundamental nuclear material control plan. This 

revision has been structured to serve as a direct outline for licensees to use in preparing their 

MC&A plan and follows the structure and format of other guidance on MC&A plans required by 

Title 10 of the Code of Federal Regulations (10 CFR) Part 74, “Material Control and Accounting 

of Special Nuclear Material,” Subparts C, “Special Nuclear Material of Low Strategic 

Significance,” and D, “Special Nuclear Material of Moderate Strategic Significance.”

This revised structure for NUREG-1280 reflects the requirements of 10 CFR 74.3, 

10 CFR 74.51, 10 CFR 74.53, 10 CFR 74.55, 10 CFR 74.57, and 10 CFR 74.59, and includes 

guidance for implementing the new requirements in 10 CFR 74.59 pertaining to tamper-safing, 

and the designation of material balance areas and item control areas. This NUREG applies to 

NRC licensees authorized to possess and use 5 or more formula kilograms of strategic special 

nuclear material (often referred to as a “Category I” quantity of material).

All other modifications involve format and editorial changes designed to provide clarifications 

and facilitate preparation or revision of the required MC&A plan.

v NUREG-1280, Revision 2

CONTENTS

ABSTRACT...............................................................................................................................iii

CONTENTS............................................................................................................................... v

ABBREVIATIONS .....................................................................................................................ix

1. INTRODUCTION................................................................................................................... 1

2. GENERAL PERFORMANCE OBJECTIVES, RELATED REQUIREMENTS, 

COMMITMENTS, AND ACCEPTANCE CRITERIA ............................................................. 3

3. PROCESS MONITORING .................................................................................................... 9

3.0 Regulatory Intent............................................................................................................. 9

3.1 Process Subdivision and Measurement Points...............................................................10

3.2 Material Control Tests ....................................................................................................11

3.3 Location Categorization..................................................................................................15

3.4 Material Substitution.......................................................................................................16

3.5 Process Monitoring Exceptions ......................................................................................17

3.6 Trend Analysis ...............................................................................................................18

3.7 Research and Development Operations.........................................................................19

3.8 Commitments and Acceptance Criteria ..........................................................................20

4. ITEM MONITORING ............................................................................................................21

4.0 Regulatory Intent............................................................................................................21

4.1 Item Loss Detection........................................................................................................21

4.2 Item Identification and Classification ..............................................................................22

4.3 Accessibility and Storage Controls .................................................................................24

4.4 Accounting and Control Procedures ...............................................................................26

4.5 Item Measurements........................................................................................................26

4.6 Item Verification .............................................................................................................27

4.7 Sample Items .................................................................................................................29

4.8 Commitments and Acceptance Criteria ..........................................................................31

5. ALARM RESOLUTION........................................................................................................33

5.0 Regulatory Intent............................................................................................................33

5.1 Alarm Resolution Procedures.........................................................................................33

5.2 Types of Alarms .............................................................................................................35

5.3 Response Time ..............................................................................................................39

5.4 Item Discrepancies.........................................................................................................40

5.5 Alarm Reporting .............................................................................................................42

5.6 Alleged Thefts ................................................................................................................43

5.7 Commitments and Acceptance Criteria ..........................................................................44

6. MANAGEMENT STRUCTURE AND PERSONNEL QUALIFICATION 

AND TRAINING..................................................................................................................45

6.0 Regulatory Intent............................................................................................................45

6.1 Corporate Organization ..................................................................................................45

6.2 Plant or Site Organization...............................................................................................45

6.3 Material Control and Accounting Organization................................................................46

6.3.1 Responsibilities and Authority ...............................................................................46

6.3.2 Material Control and Accounting Procedures ........................................................47
NUREG-1280, Revision 2 vi

6.3.3 Human Errors........................................................................................................48

6.3.4 Job Performance Aids...........................................................................................49

6.4 Training and Qualification Requirements........................................................................50

6.4.1 Training Program ..................................................................................................50

6.4.2 Qualification Program............................................................................................51

6.5 Material Control and Accounting Program Description ...................................................51

6.5.1 Automation of Material Control and Accounting.....................................................52

6.5.2 Human Error Quality Control.................................................................................52

6.6 Commitments and Acceptance Criteria ..........................................................................54

7. MEASUREMENTS...............................................................................................................57

7.0 Regulatory Intent............................................................................................................57

7.1 Measurement Points ......................................................................................................57

7.2 Measurement Systems...................................................................................................58

7.2.1 Bulk Measurement Systems..................................................................................59

7.2.2 Analytical Measurement Systems .........................................................................59

7.2.3 Nondestructive Assay Measurement Systems ......................................................60

7.2.4 Other Measurement Systems................................................................................60

7.3 Measurement Uncertainties............................................................................................60

7.4 Measurement Procedures ..............................................................................................60

7.5 Scrap Control .................................................................................................................61

7.6 Commitments and Acceptance Criteria ..........................................................................61

8. MEASUREMENT CONTROL SYSTEM ...............................................................................65

8.0 Regulatory Intent............................................................................................................65

8.1 Organization and Management ......................................................................................65

8.1.1 Functional Relationships .......................................................................................65

8.1.2 Procedures ...........................................................................................................65

8.1.3 Contractor Program Audits and Reviews...............................................................66

8.2 Calibrations ....................................................................................................................66

8.3 Control Standards ..........................................................................................................68

8.4 Replicate Sampling ........................................................................................................70

8.5 Control Limits .................................................................................................................71

8.5.1 Measurement Control Data Analysis .....................................................................72

8.5.2 Response Actions .................................................................................................72

8.6 Commitments and Acceptance Criteria ..........................................................................73

9. STATISTICS........................................................................................................................79

9.0 Regulatory Intent............................................................................................................79

9.1 Determination of Measurement Uncertainties.................................................................79

9.2 Determination of the Standard Error of Inventory Difference ..........................................81

9.3 Bias Corrections.............................................................................................................82

10. PHYSICAL INVENTORIES................................................................................................85

10.0 Regulatory Intent..........................................................................................................85

10.1 General Description......................................................................................................85

10.2 Organization, Procedures, and Schedules ...................................................................85

10.3 Description of Typical Item Strata.................................................................................86

10.4 Facility Preparation.......................................................................................................86

10.5 Conducting Physical Inventories...................................................................................86

10.6 Inventory Reconciliation ...............................................................................................89
vii NUREG-1280, Revision 2

10.7 Commitments and Acceptance Criteria ........................................................................90

11. SHIPMENTS AND RECEIPTS...........................................................................................97

11.0 Regulatory Intent..........................................................................................................97

11.1 Receiving Procedure ....................................................................................................97

11.2 Evaluation of Shipper-Receiver Differences .................................................................97

11.3 Shipping Procedure......................................................................................................98

11.4 Commitments and Acceptance Criteria ........................................................................98

12. SCRAP CONTROL..........................................................................................................101

12.0 Regulatory Intent........................................................................................................101

12.1 Location .....................................................................................................................101

12.2 Processing .................................................................................................................101

12.3 Measurements ...........................................................................................................101

12.4 Inventory Control........................................................................................................101

12.5 Recovery of Offsite Scrap...........................................................................................102

12.6 Commitments and Acceptance Criteria ......................................................................102

13. ASSESSMENT AND REVIEW OF THE MATERIAL CONTROL 

AND ACCOUNTING PROGRAM.....................................................................................105

13.0 Regulatory Intent........................................................................................................105

13.1 General Description....................................................................................................105

13.2 Report of Findings and Recommendations.................................................................106

13.3 Management Review and Response to Report Findings and Recommendations.......107

13.4 Commitments and Acceptance Criteria ......................................................................107

14. DESIGNATION OF MATERIAL BALANCE AREAS, ITEM CONTROL AREAS, 

AND CUSTODIANS.........................................................................................................111

14.0 Regulatory Intent........................................................................................................111

14.1 Material Control Boundaries .......................................................................................111

14.2 Custodians .................................................................................................................111

14.3 Commitments and Acceptance Criteria ......................................................................111

15. TAMPER-SAFING ...........................................................................................................113

15.0 Regulatory Intent........................................................................................................113

15.1 Characteristics of Tamper-Safing Devices..................................................................113

15.2 Use of Tamper-Safing Devices...................................................................................114

15.3 Description of Tamper-Safing Records.......................................................................114

15.4 Commitments and Acceptance Criteria ......................................................................115

16. RESOLVING INDICATIONS OF LOSS, THEFT, DIVERSION,

OR MISUSE OF SPECIAL NUCLEAR MATERIAL AND STRATEGIC 

SPECIAL NUCLEAR MATERIAL....................................................................................117

16.0 Regulatory Intent........................................................................................................117

16.1 Methods and Procedures for Identifying Indicators .....................................................117

16.2 System and Procedures for Investigating and Resolving Loss Indicators ...................117

16.3 Response Actions for Unresolved Indicators ..............................................................118

16.4 Documentation Requirements ....................................................................................118

16.5 Commitments and Acceptance Criteria ......................................................................119
NUREG-1280, Revision 2 viii

17. INFORMATIONAL AID FOR ASSISTING IN THE INVESTIGATION AND 

RECOVERY OF MISSING SPECIAL NUCLEAR MATERIAL AND 

STRATEGIC SPECIAL NUCLEAR MATERIAL................................................................121

17.0 Regulatory Intent........................................................................................................121

17.1 Types of Information...................................................................................................121

17.2 Information Indicating Possible Losses of Special Nuclear Material/Strategic 

 Special Nuclear Material.............................................................................................121

17.3 Information on Resolving Indications of Missing Special Nuclear 

 Material/Strategic Special Nuclear Material ................................................................122

17.4 Commitments and Acceptance Criteria ......................................................................123

18. RECORDKEEPING .........................................................................................................125

18.0 Regulatory Intent........................................................................................................125

18.1 Description of Records ...............................................................................................125

18.2 Program and Controls for Ensuring an Accurate and Reliable Record System...........126

18.3 Commitments and Acceptance Criteria ......................................................................127

19. GLOSSARY.....................................................................................................................131

20. REFERENCES ................................................................................................................137
ix NUREG-1280, Revision 2

ABBREVIATIONS

CAA controlled access area

CFR Code of Federal Regulations

DOE U.S. Department of Energy

FKG formula kilogram

IAEA International Atomic Energy Agency

ICA item control area

ID inventory difference

JPA job performance aid

MAA material access area

MBA material balance area

MC&A material control and accounting

MOX mixed oxide

NDA nondestructive assay

NMMSS Nuclear Materials Management and Safeguards System

NRC U.S. Nuclear Regulatory Commission

R&D research and development

SEID standard error of the inventory difference

SNM special nuclear material 

SSNM strategic special nuclear material

SQ significant quantity

TID tamper-indicating device

wt% weight percent

Chemical Symbols:

K2Cr2O7 potassium dichromate U-235 uranium-235

Pu plutonium U-238 uranium-238

PuO2 plutonium dioxide UO2 uranium dioxide

Pu-238 plutonium-238 U3O8 urano-uranic oxide

U uranium UF6 uranium hexafluoride

U-233 uranium-233 UNH uranyl hexahydrate

U-234 uranium-234

1 NUREG-1280, Revision 2

1. INTRODUCTION

Title 10 of the Code of Federal Regulations (10 CFR) Part 70, “Domestic Licensing of Special 

Nuclear Material,” and 10 CFR Part 74, “Material Control and Accounting of Special Nuclear 

Material,” include the principal requirements for licensing special nuclear material (SNM). In 

particular, 10 CFR 70.22(b) specifies that a license application must fully describe the 

applicant’s program for the control and accounting of such SNM and demonstrate how the 

program will comply with the graded material control and accounting (MC&A) requirements of 

10 CFR Part 74, Subparts B through E.

This guidance document describes the standard format and content suggested by the 

U.S. Nuclear Regulatory Commission (NRC) for use in preparing MC&A plans for the 

possession and use of a formula quantity (i.e., 5 formula kilograms (FKG) or more) of strategic 

special nuclear material (SSNM). This document also provides recommended acceptance 

criteria for use by licensees and NRC licensing reviewers. Criteria are included as examples, 

and each licensee should develop an MC&A plan that takes into account the unique features of 

its particular operation. Where additional guidance is available on particular topics, the 

acceptance criteria section includes an appropriate reference. 

A licensee’s general MC&A program, and its specific MC&A plan, must demonstrate that it will 

achieve and maintain the basic capabilities specified in the following regulations:

• 10 CFR 74.51, “Nuclear Material Control and Accounting for Strategic Special Nuclear 

Material”

• 10 CFR 74.53, “Process Monitoring”

• 10 CFR 74.55, “Item Monitoring”

• 10 CFR 74.57, “Alarm Resolution”

• 10 CFR 74.59, “Quality Assurance and Accounting Requirements”

The licensee must also demonstrate how such capabilities are used to meet the general 

performance objectives stated in 10 CFR 74.3 and 10 CFR 74.51(a). After approving an MC&A

plan and imposing it as a license condition, the NRC will verify the adequacy of a licensee's 

MC&A program by inspecting to determine conformance with commitments and practices 

described in the MC&A plan.

Because 10 CFR 74.3, 10 CFR 74.51, 10 CFR 74.53, 10 CFR 74.55, 10 CFR 74.57, and 

10 CFR 74.59 are performance-oriented regulations, they do not contain a detailed set of 

technical specifications. With this flexibility, applicants and licensees have many alternatives 

with regard to how their MC&A program is designed, managed, and operated, which permits a 

risk-informed, performance-based approach that focuses on MC&A activities most important to 

safeguards. Accordingly, this document does not cover all possible methodologies that a 

licensee might use to meet the MC&A requirements. Instead, this document provides examples 

of acceptable MC&A approaches that a licensee may use. This guidance is intended for use by
NUREG-1280, Revision 2 2

applicants, licensees, and the NRC safeguards licensing reviewers. Acceptance criteria are not 

to be regarded as rigid, fixed standards. That is, a lower effectiveness of one capability relative 

to a particular aspect is acceptable if there is a compensating system feature, or combination of 

features, that provides an overall effective safeguards system. In the final analysis, an NRC 

reviewer must find that the applicant’s or licensee’s MC&A plan provides adequate assurance 

that all applicable regulatory requirements will be met.

The introductory material to this document describes the basis of the eight general performance 

objectives of 10 CFR 74.3 and 10 CFR 74.51(a). The chapters that follow incorporate and 

expand on the general performance objectives and describe the MC&A features and capabilities

needed to meet the performance objectives. Together, Chapters 3-18 provide licensees an 

acceptable outline for establishing MC&A plans. 

The NRC will make the body of an approved MC&A plan a condition of the license, in 

accordance with 10 CFR 70.32(c), and compliance with the MC&A plan commitments and 

pertinent procedures will be inspectable. Explanations and discussions appearing in the body of 

the plan should be sufficiently detailed and precise so that the NRC licensing reviewers, the 

NRC inspectors, and licensee personnel responsible for developing and implementing the plan 

have a clear and common understanding of what the MC&A plan requires.

The annex (or appendix) of an MC&A plan should provide supplementary and general 

information about the facility and the MC&A program and subsystems (e.g., copies of blank 

record forms, site map, process diagrams, an example standard error of the inventory 

difference (SEID) calculation). The annex will not be incorporated as a condition of license and 

will not be the basis for inspection. Thus, descriptions presented by the licensee to meet 

regulatory requirements must be in the plan itself, rather than the annex, and must provide 

adequate detail so as not to depend greatly on examples or supplementary information in the 

annex for proper understanding. Procedures detailed in the annex may be changed without 

NRC approval or notification provided that plan commitments and capabilities are not degraded. 

Preparation of an MC&A plan with this standard format will assist the NRC in evaluating the plan 

and in standardizing the licensing and review process. However, the NRC does not require 

conformance with the standard format. An applicant may use a different format if it provides an 

acceptable level of completeness and detail.
3 NUREG-1280, Revision 2

2. GENERAL PERFORMANCE OBJECTIVES, RELATED 

REQUIREMENTS, COMMITMENTS,

AND ACCEPTANCE CRITERIA

General Performance Objectives

The regulations in 10 CFR 74.3 and 10 CFR 74.51(a) set forth the eight general MC&A 

performance objectives applicable to licensees authorized to possess and use a formula 

quantity of SSNM. As indicated below, for licensees authorized to possess Category I amounts 

of material, these performance objectives apply to SNM and SSNM. The following paragraphs 

discuss the basis of these general performance objectives and the related requirements in 

Subpart E, “Formula Quantities of Strategic Special Nuclear Material,” of 10 CFR Part 74.

1. Maintain accurate, current, and reliable information on, and confirm the quantities 

and locations of, SNM/SSNM in the licensee’s possession.

The purpose of this performance objective is to verify the presence of all SNM and SSNM held 

by the licensee and to detect the occurrence of any significant loss, including possible theft or 

diversion. To maintain current information on all such SNM/SSNM in their possession,

licensees should have in place a program that provides timely, accurate, and reliable 

information about the quantity and location of SNM/SSNM in their possession. Accurate 

information means that quantities for plutonium (Pu), the element uranium (U), and the isotopes 

U-235 and U-233 are based on measured values or on reliable information. Reliable 

information means that the quantity of SNM/SSNM in an item and the location of all items are 

known (except for items in solutions with a concentration of less than 5 grams of U-235 per liter 

and items of waste destined for burial or incineration). The location designations should be 

specific enough to provide for the retrieval of the items in a prompt manner. Reliable 

information also means that the quantities and locations of all nonexempt SNM/SSNM and 

items listed in the accounting records are correct and verifiable.

The licensee should accurately account for all SNM/SSNM it receives and ships by maintaining 

reliable records based on accurate measurements. When a shipment is received, the licensee 

should begin monitoring the movement and location of the material within the facility using item 

control procedures to (1) monitor the location and integrity of items until they are processed and 

(2) ensure all SNM/SSNM quantities of record associated with receipts, shipments, discards, 

and ending inventory are based on measurements. Chapter 4 of this document provides 

recommendations for meeting the performance objectives for the item control program.

Chapters 7 and 8, respectively, include recommendations for the MC&A measurement and 

measurement control subsystems. Monitoring the material in process may involve the use of 

process or material control data. To support this function, the licensee should maintain a

detailed and accurate recordkeeping system for the generated data that provides knowledge of 

the material’s location on a timely basis. 

The licensee must conduct total plant physical inventories at intervals not to exceed 6 calendar 

months, in accordance with 10 CFR 74.59(f). The licensee must conduct each physical 

inventory in a manner to ensure the detection of any actual significant loss, including possible 

theft or diversion, by evaluating each inventory difference (ID) using an SEID that is less than 

0.1 percent of the active inventory, in accordance with 10 CFR 74.59(f). As a result, the 

investigation and reporting of any ID that exceeds three times the SEID is equivalent to a 
NUREG-1280, Revision 2 4

hypothesis test that provides 90-percent power for detecting a discrepancy as small as 

0.4 percent of active inventory at a false alarm rate of 5 percent.

The licensee should verify the presence of all SNM/SSNM held under its license, as 

documented in accounting records. This verification is normally accomplished by a shutdown 

and cleanout of processing equipment, measurement of cleanout materials and measurement of 

any materials not previously measured in their existing form, visual verification (on a 

100-percent basis) of the presence of all possessed SNM/SSNM items (by means of unique 

item identities), and confirmation of the SNM/SSNM quantities associated with unencapsulated 

and unsealed items on ending inventory. However, the licensee may use a dynamic (i.e., 

nonshutdown) inventory of some or all processing equipment if the measurement uncertainty 

associated with the total material balance (for the inventory period) is within the constraint of 

0.1 percent of active inventory specified in 10 CFR 74.59(e)(5).

Chapter 10 of this document details recommendations pertaining to physical inventories. In 

summary, a total plant physical inventory should involve the following:

• verifying the presence, on a 100-percent basis, of all uniquely identified SNM/SSNM

items listed in the accounting records

• measuring (by direct measurement or, if direct measurement is not feasible, by indirect 

measurement) all bulk SNM/SSNM quantities on hand (i.e., all SNM/SSNM not in item 

form)

• measuring any items not previously measured

• verifying the identity and integrity of all encapsulated items and items affixed with 

tamper-indicating devices (TIDs)

• measuring an SNM/SSNM-related parameter for a sample of randomly selected 

unencapsulated and unsealed items, based on a statistical sampling plan, to verify the 

previously measured quantities of SNM/SSNM contained in such items

The licensee should manage and maintain the physical inventory program independent of the 

production or operations organization, but the program should not be excluded from using 

process monitoring and production control data.

2. Detect, respond to, and resolve any anomaly indicating a possible loss, theft, 

diversion, or misuse of SNM/SSNM.

3. Permit rapid determination of whether an actual loss, theft, diversion, or misuse of 

SNM/SSNM has occurred.

The purpose of these two performance objectives is to ensure that licensees can adequately 

detect and respond to indications of possible loss, theft, diversion, or misuse of SNM/SSNM and 

rapidly determine whether a loss, theft, diversion, or misuse of SNM/SSNM occurred.

As discussed further in Chapter 16 of this document, to meet the requirements of 

10 CFR 74.3(b) and 10 CFR 74.3(c), as well as 10 CFR 74.51(a), the licensee or applicant 

should have a formalized program to promptly detect, respond to, and resolve any anomaly that 
5 NUREG-1280, Revision 2

may indicate a possible loss of SNM/SSNM. Resolution of such anomalies means that the 

licensee has made a rapid determination as to whether an actual loss of a significant quantity

(SQ) of SNM/SSNM has occurred, including possible theft or diversion. A licensee should 

investigate and resolve an anomaly detected during a material balance closure in accordance 

with the requirements of 10 CFR 74.59(f)(1).

Resolution of an anomaly depends on the type of indicator. Various types of anomalies at 

plants could occur from a wide range of possible underlying scenarios (e.g., from unidentified or 

inadequately monitored loss mechanisms, simple theft, complex diversions). The investigation 

and resolution process should begin with a thorough review of the MC&A records to locate 

obvious errors. These errors might include omissions of entire items, incorrect entries to 

computer programs or records, transcription errors, incorrect estimates of the amount of holdup 

in equipment, or calculation errors. A detailed examination of the MC&A records for each 

material type should identify gross errors. The next stage in the resolution process is to isolate 

the process or storage area that appears to be causing the anomaly. Once this is 

accomplished, the licensee should verify all of the information that contributed to the 

SNM/SSNM quantities for that location. If resolution still is not accomplished, the licensee 

should remeasure and sample material in the process or storage areas to verify quantities. If 

the investigation of an indicator results in a determination that an actual loss or theft has 

occurred, the licensee must report the loss or theft to the NRC, in accordance with

10 CFR 74.11, “Reports of Loss or Theft or Attempted Theft or Unauthorized Production of 

Special Nuclear Material.”

4. Provide information to aid in the investigation and recovery of missing SNM/SSNM

in the event of an actual loss, theft, diversion, or other misuse.

The purpose of this performance objective in 10 CFR 74.3(d) and 10 CFR 74.51(a) is to ensure 

that licensees provide adequate assistance in any investigations of an actual loss, theft, 

diversion, or misuse of SNM/SSNM conducted by a government agency. If the NRC or other 

government agencies deem it necessary to conduct an investigation relating to actual or highly 

suspected events pertaining to missing material, the licensee should provide any information 

deemed relevant to the recovery of material involved in a loss, theft, or diversion. The licensee 

must provide all information that it recognizes as being relevant, whether or not the investigators 

request it. Chapter 17 of this document provides additional information and recommendations 

pertaining to providing information to aid in investigations.

5. Control access to MC&A information that might assist adversaries to carry out acts 

of theft, diversion, misuse, or radiological sabotage involving SNM/SSNM.

The purpose of this performance objective in 10 CFR 74.3(e) and 10 CFR 74.51(a) is to 

implement the practices and procedures needed to provide effective material control and 

material accounting with respect to deterrence and detection of theft, diversion, misuse, or 

radiological sabotage involving SNM/SSNM. Components of control access to MC&A 

information may include, for example, access control, material containment, and material 

surveillance. Effective control systems should be multilayered, and licensees should use 

redundant systems to eliminate the consequence of a single-point failure.

The licensee should implement an effective quality assurance program that minimizes the 

possibility of potential failures for the MC&A program. These control measures can contribute to 

deterrence of material loss, theft, diversion, or misuse by providing necessary checks and 

balances. The licensee should carefully monitor and manage access control involving all 
NUREG-1280, Revision 2 6

movements of people and materials into and out of the material access areas (MAAs). 

Adequate containment and surveillance measures should ensure that the integrity of nuclear 

material values is maintained.

The licensee should give primary attention to preventing errors or mistakes by MC&A personnel 

and to preventing violations of procedures or compromise of MC&A information and data. The 

licensee should establish a system of balances and checks to ensure data accuracy, and this 

system should detect any instances of unauthorized access to data. Mistakes resulting from

inadequate training, accidents, improper equipment operation or maintenance, or any other 

unintentional actions can cause the MC&A program to lose its effectiveness.

In addition to the 10 CFR 74.3 general performance objectives, which focus on the prevention of 

theft, licensees authorized to hold SSNM must, in accordance with 10 CFR 74.51(c), be able to 

detect the falsification of data that could conceal the diversion of SNM or SSNM by (1) a single 

individual, including an employee in any position, or (2) collusion between two individuals, one 

or both of whom have authorized access to SNM or SSNM.

The MC&A program and plan need to protect against only a single insider, providing that such 

an individual does not have authority within the physical protection system that would permit him

or her to participate in a conspiracy aimed at defeating the safeguards system. If an MC&A

individual does have authority within the physical protection system, then the MC&A program 

and plan is required to protect against the coverup of a collusion of that individual with any other 

individual having MC&A authority. This approach should relieve licensees of most of the burden 

that would result from requiring a totally redundant system while still maintaining the ability of 

the MC&A program and plan to provide an extra level of independent protection and an added 

measure of assurance that the safeguards system as a whole has not been compromised.

The licensee should analyze all positions having responsibility within the 10 CFR Part 74 MC&A 

program to determine whether any such positions also have responsibility within the physical 

protection system developed under 10 CFR Part 73, “Physical Protection of Plants and 

Materials.” A safeguards manager might be an example of such a position. If this position 

includes both MC&A and physical protection responsibilities, the licensee would have to develop 

procedures to ensure that, when an individual in this job is performing an MC&A function, he or 

she performs the function in the presence of at least two other people (industry procedures 

often reference this as the “three-person rule”), that performance of the function be 

independently checked later by a third party, and that abuse of authority is otherwise protected 

against.

To address collusion concerns, the licensee would need to protect an MC&A function performed 

by a worker without physical protection system authority against a single insider threat,

particularly if such a worker has “hands on” access to formula quantities of SSNM.

6. Provide ongoing confirmation of the presence of SSNM in assigned locations.

The purpose of this performance objective in 10 CFR 74.51(a)(1)(i) is to ensure timely plantwide 

detection of the loss of items that total 5 FKG or more. To achieve this capability, the licensee 

should verify the presence and integrity of selected SSNM items on a periodic basis. The 

required frequency of tests for missing items, as described in 10 CFR 74.55, is graded 

according to the relative attractiveness of the material type in the item, the ease with which the 

item could be diverted without being observed, and the degree of surveillance and containment 
7 NUREG-1280, Revision 2

provided for by the material control and physical security systems. Chapter 4 of this document 

provides additional information and recommendations pertaining to ongoing confirmation of the 

presence of SSNM in assigned locations.

7. Provide for the timely detection of the possible abrupt loss of 5 FKG or more of 

SSNM from an individual unit process.

8. Permit rapid determination of whether an actual loss of 5 FKG or more of SSNM 

occurred.

The purpose of these performance objectives in 10 CFR 74.51(a)(1)(ii)–(iii) and the 

requirements in 10 CFR 74.53 is to have a quality control program that will provide early 

indications of diversion or theft and a prompt detection system for significant abrupt diversions 

of 5 FKG or more. Through prompt detection, the licensee can initiate response and recovery 

actions soon after a loss event while the circumstances surrounding the loss are fresh in the 

minds of cognizant personnel and materials are available for remeasurement. In addition, fewer 

changes in process conditions, inventories, in-process holdups, and item locations would occur, 

thus enhancing the probability of resolution. The detection times for a 5-FKG loss are 

maximums; hence, a licensee may use shorter intervals for specific unit processes. Chapter 3

of this document provides additional information and recommendations pertaining to the timely 

detection of a possible abrupt loss of 5 FKG.

Commitments and Acceptance Criteria Pertaining to General Performance Objectives

In its MC&A plan, the applicant or licensee should provide definitive commitments that adhere to 

the regulatory requirements and meet the acceptance criteria with respect to these general 

performance objectives and corresponding program capabilities. The MC&A plan should state 

these commitments. Chapters 3 through 8 and 10 through 18 of this document list the 

commitments and acceptance criteria.

The following chapters of this document incorporate and expand on the performance objectives 

and on the MC&A program and plan capabilities specified in 10 CFR 74.3, 10 CFR 74.51, 

10 CFR 74.53, 10 CFR 74.55, 10 CFR 74.57, and 10 CFR 74.59. The chapters are arranged in 

a format and sequence that will provide applicants and licensees an outline for their required

MC&A plans.

9 NUREG-1280, Revision 2

3. PROCESS MONITORING

3.0 Regulatory Intent

The intent of the 10 CFR 74.53 process monitoring requirements is to have a quality control 

program that will provide early indications of diversion or theft and a prompt detection system for 

significant abrupt diversions of 5 FKG or more. Through prompt detection, the licensee can 

initiate response and recovery actions soon after a loss event while circumstances surrounding 

the loss are fresh in the minds of cognizant personnel and materials are available for 

remeasurement. In addition, fewer changes in process conditions, inventories, in-process 

holdups, and item locations would occur, thus enhancing the probability of resolution. The 

detection times for a 5-FKG loss are maximums; hence, a licensee may use shorter intervals for 

specific unit processes if so desired.

The regulations in 10 CFR 74.53(a) require licensees subject to 10 CFR 74.51 to monitor 

internal transfers, storage, and processing of SSNM. The process monitoring must achieve the 

detection capabilities described in 10 CFR 74.53(b) for all SSNM, except for the material listed 

in 10 CFR 74.53(a)(1) through (4).

As required by 10 CFR 74.53(b), the licensee must establish, for each process unit, a 

production quality control program capable of monitoring the status of material in process. The 

program shall include the following:

• a statistical test that has at least a 95-percent power of detecting an abrupt loss of 

5 FKG within 3 working days of a loss of Category IA material from any accessible 

process location and 7 calendar days of a loss of Category IB material from any 

accessible process location (10 CFR 74.53(b)(1))

• a quality control test whereby results greater than both three times the estimated 

standard deviation of the process difference estimator and 25 grams of SSNM are 

investigated (10 CFR 74.53(b)(2))

• a trend analysis for monitoring and evaluating sequences of material control test results 

from each unit process to determine whether they indicate a pattern of losses or gains 

that are of safeguards significance (10 CFR 74.53(b)(3))

The regulations in 10 CFR 74.53(c) require that, for research and development (R&D) 

operations that are exempt from 10 CFR 74.53(b), the licensee shall (1) perform material 

balance tests on a lot or batch basis, as appropriate, or at intervals not to exceed 30 calendar 

days, whichever is sooner, and investigate any difference greater than 200 grams of plutonium 

or U-233 or 300 grams of U-235 that exceeds three times the estimated SEID and (2) evaluate 

material balance results generated during an inventory period for indications of measurement 

biases or unidentified loss streams and investigate, determine the cause of, and institute 

corrective action for cumulative IDs generated during an inventory period that exceed 3 FKG of 

SSNM.

By design, R&D operations are dynamic in nature. Thus, the prompt loss detection techniques 

that depend upon process yields are inappropriate for loss detection. Taking into account the 

low throughput of such operations, periodic material balance tests on a batch or monthly basis 

are deemed acceptable for loss detection.
NUREG-1280, Revision 2 10

A working day is any 24-hour calendar day (from 12:01 AM to 12:00 midnight) during which 

material processing activities occur and there is material handling, except for those calendar 

days in which the only processing and material-handling activities are limited to the first or last 

30 minutes of the day, or both the first and the last 30 minutes of the day, because of the ending 

or beginning of shift scheduling times. A day during which activities such as maintenance of 

equipment, cleanup, and autoclave monitoring occur would not be considered a work day,

unless such a day involved the handling of SSNM. 

3.1 Process Subdivision and Measurement Points

The MC&A plan should describe the subdivision of the process to meet the unit detection 

requirements, the associated parameters to be measured, and the measurement points. The 

plan may include a diagram or listing to document this information.

The number of control units into which a facility can be divided is not limited or restricted. Loss

detection sensitivity, false alarm rate, and loss localization capability are key determining 

factors.

Bulk materials, including nontamper-safed containers of SSNM (i.e., not within a vault or 

permanently controlled access area (CAA)), as well as materials in process equipment, should 

be covered. In general, this applies to material that must be measured to verify its presence, 

rather than having its identification number and seal or encapsulation integrity checked.

Acceptance Criteria:

• All SSNM in bulk form in the MAA is within the span of a material control test. 

Exceptions include (1) low-level waste that meets the criteria in 10 CFR 73.46(c)(6), 

(2) laboratory samples each containing less than 0.05 FKG, (3) SSNM in R&D

operations with throughputs of less than 5 FKG during any 7 consecutive days, and 

(4) SSNM in waste treatment operations conducted outside an MAA (e.g., incinerator).

• The following criteria are appropriate in determining control unit boundaries:

− Material control tests should be performed on units generally consistent with 

readily assessable measurement points that naturally result from the process 

design. Process units should not be divided into smaller units for material control 

tests if such subdivision would cause the standard deviation of the test statistic to 

increase from below 850 formula grams U-235 (or equivalent units for tests not 

based on U-235) to above 850 formula grams U-235 unless such subdivision is 

necessary to meet the timeliness criteria in 10 CFR 74.53(b)(1).

− Batch transfers should be used wherever they occur.

− Process variabilities should be localized to a control unit.

− Concentration differences between feed and product stream output should be 

minimized wherever possible.

− Process units that operate continuously should be separated (in terms of defining 

control unit test boundaries) from those that operate in a batch mode.
11 NUREG-1280, Revision 2

− False alarm rates should be minimized. The number of false alarms per 

inventory period should be less than 1 percent of all tests.

3.2 Material Control Tests

The MC&A plan should describe the material control tests for each unit process. The 

description should include the following:

• identification of the test statistic

• the amounts and types of data used to establish uncertainties (sigmas)

• tests for normality

• means of handling nonnormal data

• tests for outliers

• methods for establishing alarm thresholds

• criteria for modifying alarm thresholds

• the basis for assignment of the start times for each material control test

The annex to the MC&A plan should include the following:

• a detailed example alarm threshold calculation for a process unit

• a tabulation of the threshold values for all process units

• a tabulation of the detection times associated with each material control test

• the justification for the derivation of each threshold value

• a listing of Category IA and IB materials and the justification for the lower classification of 

the latter

Acceptance Criteria:

• The licensee has developed a system of material control tests for detecting abrupt losses of 

bulk material from single units or locations within the facility. The material control tests are 

capable of detecting a 5-FKG loss with at least 95-percent power of detection. The material 

control tests have the following characteristics:

- Each material control test encompasses the SSNM in a definite unit or location or over a 

span of locations comprising a segment of the process or a single point in the process.

- Automated or manual records of the location, movement, quantity, and identity of SSNM 

are maintained as needed to perform the material control tests for abrupt loss detection.
NUREG-1280, Revision 2 12

- The material control test is based on a comparison of a measured value of a quantity of 

material or of a process variable with a reference value. The reference value is the 

expected or predicted quantity of material or value of the process variable in the 

absence of diversion or unexpected loss. Examples of possible material control tests 

include the following:

• SSNM material balance

• mass (weight) balance

• volume balance

• yield versus expected or predicted yield

• liquid level versus predicted level

• solution density versus predicted density

• flow rate versus predicted flow rate

• bulk powder volume or volume times bulk density versus predicted 

quantity

• nondestructive assay (NDA) value versus predicted value

• isotopic ratio versus predicted value

• number of units, such as pellets, elements, or pins, versus predicted 

number

• process control parameters, such as pH, reagent volume, or extraction 

efficiency, versus predicted values

- Each material control test has an action threshold (critical value) which, if exceeded, 

initiates the alarm resolution procedures prescribed in 10 CFR 74.57. In general, the 

action threshold or critical value can be set by a formula of the following type:

A = G Kσx (when x increases upon real loss)

A = G Kσx (when x decreases upon real loss)

where:

A = alarm threshold in terms of test value obtained for x (as formula grams 

SSNM)

G = goal quantity = 5,000 formula grams or less

x = test statistic (parameter) such as feed input minus product output for a 

given test period, as formula grams SSNM
13 NUREG-1280, Revision 2

= test statistic mean, assuming the null hypothesis, H0, is true (H0: L=0), as 

formula grams SSNM (Note: This mean value can be either positive or 

negative.)

L = loss quantity

K = factor based on probability of detection

σx = standard deviation of the test statistics, as formula grams SSNM

Key considerations applicable to this determination include the following:

- If the distribution of the source data can be reasonably represented by a single 

normal model after the effects of human errors have been eliminated, use 

K = 1.65 to achieve 95-percent detection probability.

- If an analysis of test data indicates the presence of multiple distributions, one of 

the following actions would be appropriate:

• Undertake an in-depth study to identify the sources of error and the 

adjustments that should be made, as appropriate, so that a single normal 

distribution adequately represents the data.

• Estimate the parameters (x, σx) using a computer program as necessary 

to maximize the likelihood function; then determine the critical point by 

integrating the probability density function to the probability of interest.

• Determine whether the presence of multiple distributions is the result of 

concomitant data which occurred as the result of some recognized 

change that happened during the test period (e.g., new and recycled 

material processed through an operation). If such data are available, the 

data should be split into subsets for testing.

- If a nonzero x is used, a study should be conducted to identify the causes. The 

chosen x should minimize the σx for the test statistic.

• The action thresholds for the material control tests are updated, at least annually, based 

on the previous 6 months of operating data and as supported by the analysis of test 

data.

• When data do not seem to fit a normal distribution, the licensee should evaluate whether

some mathematical function of the data values will fit (transformation of data). A 

commonly used transformation is logarithms, which is the basis for the lognormal 

distribution.

• Although no limit on the magnitude of the measurement or process uncertainty is stated, 

establishment of alarm thresholds indirectly limits the magnitude of these errors. That is, 

when the standard deviation of the test statistic becomes a large fraction of G, there is 

an excessive number of false alarms.

• The combined quality of the material control test and loss resolution decisions shall 

permit alarms remaining unresolved after the completion of investigative activities to be 
NUREG-1280, Revision 2 14

good indicators of an actual loss. To achieve this objective, the licensee should 

demonstrate that the statistically expected number of unresolved false alarms will be 

less than 0.10 per inventory period for all abrupt bulk loss alarms exceeding 5 FKG (i.e., 

the predicted number of such unresolved alarms should be less than 1 in 10 inventory 

periods).

• The action thresholds are based on statistical hypothesis tests derived from the 

variances of the test statistics or on other technical bases for which it can be shown that 

the power of the test for loss is satisfactory.

• The measurement variances assumed by the licensee are either supported by published 

typical values (see Reilly and Evans (1977); Rogers (1983); or Reilly et al. (1991)), the 

licensee’s measurement control data, or historical data from the licensee’s process or 

other similar processes. The assumed process variances may be estimated by using 

conservative judgments based on sound engineering principles if historical performance 

data for the licensee’s process or similar processes are not available. If engineering 

judgments or typical values are used, the MC&A plan should include provisions and 

schedules for updating the estimated variances with actual performance data. The 

methods of estimating the loss detection sensitivity or the variances of loss detection 

parameters are satisfactorily explained and a credible justification for their use is given.

• The tests for detecting abrupt losses at each accessible location meet the 3- and 7-day 

detection time requirements for Category IA and Category IB materials, respectively, under 

all routine conditions expected to prevail at the location, in accordance with 10 CFR 74.55.

(Note: When detection times are interrupted by idle time caused by weekends, holidays, or 

vacations, for example, the licensee has provisions for completing the tests before the idle 

time or for conducting additional tests to cover any material control tests that will not be 

completed. The additional tests achieve the same level of detection as the principal tests.)

• The annex to the MC&A plan explains and justifies the licensee’s classification of the 

process material as Category IA and Category IB. Category IB materials must meet at least 

one of the following criteria:

(1) unusable for constructing a nuclear explosive device without further processing

(2) not susceptible to undetected removal from the MAA by an insider because of size, 

weight, or chemical hazard

(3) of such low concentrations of SSNM that excessively large bulk quantities would be 

needed to obtain a formula quantity of SSNM

• The timeliness of abrupt loss detection at a single location is based on the interval between 

the time a goal quantity of SSNM becomes accessible for diversion and the completion of 

the material control test. The start time occurs when the quantity of SSNM is first equal to or 

greater than the established goal quantity.
15 NUREG-1280, Revision 2

• Process difference estimates that exceed both three times the standard deviation of their 

estimator and 25 grams of SSNM must be investigated and the results documented. The 

investigation should as a minimum include the following:

− a review of all source data and calculations for errors

− a review of material control test results for the preceding SSNM quantity in the involved 

unit and the results of material control tests from the two adjacent units

− an interview with process operators to ascertain whether a perturbation in the process 

may have occurred

− a check of sidestreams for abnormally high SSNM content

− an assessment of the possibility that additional holdup beyond what had been projected 

may have occurred

− when necessary, a check of safety and backup systems common to several (or all) 

process units, such as ventilation filters and scrubbers, effluent monitors, and the like, 

for indications of abnormally high process losses

Differences that exceed three times the standard deviation are expected to be good quality 

control indicators for anomalies that could have an adverse impact on MC&A. In some units, 

differences of such a magnitude might trigger an alarm potentially indicative of a 5-FKG loss, in 

which case the licensee would initiate alarm resolution procedures. In other cases, the 

differences may be far less than the quantity necessary to trigger an alarm; however, 

investigative action is appropriate before the problem escalates to a more serious situation.

The problem that comes from too large a measurement or process uncertainty, which causes 

the standard deviation of the test statistic to be a large fraction of the goal quantity, is excessive 

false alarms. The rule does not limit the number of false alarms allowed. However, the alarm 

resolution requirements in 10 CFR 74.57 must be met. One approach to meeting those 

requirements is to reduce expected false alarms to a level below the acceptable number of 

irresolvable alarms. Another approach is to tolerate a fairly high rate of false alarms and have 

more accurate backup measurement systems or more accurate downstream measurements to 

help resolve the false alarms. Criteria for the acceptability of the alarm resolution approach 

provide the limits on measurement error for detection and response.

3.3 Location Categorization

The MC&A plan should identify the SSNM locations within the facility classified as inaccessible 

(relative to SSNM accessibility by a single individual).

The annex to the MC&A plan should provide the justification for classifying a location as 

inaccessible.

Acceptance Criteria:

• All SSNM locations within the facility that are considered to be inaccessible will be identified 

and the supporting rationale provided.
NUREG-1280, Revision 2 16

• For the purpose of establishing the start time for material control tests, SSNM may be 

treated as not accessible for diversion if any of the following conditions apply:

− Access to SSNM is physically precluded without the need for visible puncturing, 

breaking, or otherwise violating the integrity of the process equipment containing the 

SSNM.

− The state of the SSNM precludes diversion because of high temperature, chemical 

reactivity, radioactivity, or other chemical or physical properties.

− The removal of the SSNM from its authorized location cannot be accomplished because 

the tools or equipment needed for its movement are unavailable.

− The SSNM is a large volume of dilute solution within a large vessel, the absence of 

which (i.e., the SSNM) could not escape notice.

− The material is under continuous surveillance of two or more individuals or an electronic 

or other type of monitoring system that will detect attempts by a single individual to 

remove material from a process.

• The licensee must detect losses from any location. The concept of accessible location 

applies only to the criteria for establishing and determining the timeliness of the licensees’

detection capabilities. The detection time is the duration from when the SSNM passes a 

place from where it is accessible to diversion to the time at which its loss would be detected. 

Licensees are encouraged to have few accessible locations since the risk of material being 

stolen is reduced by minimizing opportunities for people to have access to material or to 

have access to points of remote control over material flow, if those controls could be used to 

divert the flow into unauthorized locations.

Generally, a glove box should be considered an “accessible location.” Since such activities as a 

glove change or “bagging out” operation are considered routine, a removal of material via this 

route may not be readily detectable. However, if an enforceable policy exists which states that 

all removals from a glove box must be accomplished by at least two individuals and no access 

points can be accessed without an obvious indication, a glove box may be treated as 

inaccessible.

3.4 Material Substitution

The MC&A plan should identify all credible substitute materials (for both simple and isotopic 

substitution) at each location and the method of testing for substitution or for controlling the 

substitute material to prevent or detect attempts at substitution. The plan should also describe 

the method of preventing credible substitute materials from being covertly introduced. (Note: 

Reference to the physical protection plan is permitted.)

Acceptance Criteria:

• The material control tests need only detect those losses not involving substitution unless 

credible materials are available in the same MAA in the form of uncontrolled material or are 

not prohibited as contraband from being brought into the MAA.
17 NUREG-1280, Revision 2

• Where credible substitute material is present and uncontrolled, the material control tests 

must be capable of detecting diversions employing substitution with the loss sensitivity and 

probability of detection required in 10 CFR 74.53. If uranium of a lower enrichment is a 

credible uncontrolled substitute, a material control test must be capable of detecting isotopic 

dilution. Otherwise, a test that detects replacement of plutonium or uranium SSNM by 

another element is adequate.

• Material is not a credible substitute if it satisfies any of the following:

− has physical properties, such as density, color, particle size, or other characteristics, that 

will be immediately and unequivocally recognized to differ from the SSNM by personnel 

who routinely work with the SSNM

− has chemical properties that will always cause process upsets or degradation of product 

quality severe enough to be recognized and reported to a designated individual 

responsible for initiating a response within the item period of the material control test

− is controlled by a monitoring technique or physical controls that prevent its substitution 

for SSNM

− is controlled by a material accounting test that will detect losses or diversion of the 

substitute material and, in the absence of an alarm, will provide indirect assurance that 

an SSNM diversion involving substitution has not occurred

• Acceptable controls on substitute materials might include the following:

− Access to the material is controlled through isolation in a locked limited access cabinet 

or room and access is restricted to individuals who would not be involved in the actual 

handling of SSNM during production operations.

− Periodic material balances are performed on the substitute material inventory in which 

case the balance may merely entail a weight comparison of material on starting 

inventory plus additions to inventory minus material issued for production versus the 

current inventory weight.

− Semiquantitative NDA tests are performed on intermediate product materials from 

process operations in which credible substitute materials might be introduced.

− Credible substitute materials are stored outside the MAA and introduced only in amounts 

for a shift’s or day’s production.

3.5 Process Monitoring Exceptions

Process monitoring must achieve the detection capabilities described in 10 CFR 74.53(b) for all 

SSNM, except for the types of material specified in the 10 CFR 74.53(a)(1)–(4) exceptions. The 

MC&A plan should detail the specific material types, with their locations, that are excepted from 

the 10 CFR 74.53(b) requirements. 
NUREG-1280, Revision 2 18

Acceptance Criteria:

• For low-throughput operations, such as waste compactors and incinerators where 

throughput is less than 5 FKG over a period of 95 calendar days and the measurement 

uncertainties (at the 2-sigma level) on inputs or outputs, or both, are greater than 

10 percent, the licensee performs material balances on a batch basis and makes 

appropriate corrections to the originating unit or units or area cumulative balances to the 

extent practicable. Holdup determinations are necessary only at the time of the physical 

inventory (or sooner for criticality safety reasons), and input-output differences are assessed 

only to the extent that significant trends are investigated to identify measurement biases or 

an unaccounted for loss stream.

• For samples containing greater than 0.05 FKG and scrap and waste containers in 

laboratories, the licensee performs monthly material balances. These balances may be 

accomplished by the following:

− maintaining a dynamic record of the laboratory inventory

− maintaining a continuous inventory of the contents of scrap and waste containers by 

tracking the amounts of all additions (or removals) to each container

− measuring the contents of each container monthly to detect significant discrepancies 

where “significant” is defined as more than two times the standard deviation of the 

difference estimator

3.6 Trend Analysis

Nonrandom behavior of process differences may indicate the presence of an unidentified bias, 

unmeasured loss stream, or diversion. It is important that trends be identified so that 

investigations can be initiated to uncover the cause. The MC&A plan should describe the trend 

analysis techniques that are employed to monitor sequences of process differences from 

material control tests. The description should include the decision criteria for ascertaining when 

a significant trend exists.

Acceptance Criteria:

• The licensee can accomplish the trend analysis required by 10 CFR 74.53(b)(3) by applying 

the appropriate parametric or nonparametric statistical techniques. Examples include 

Page’s test, Runs test, Dietz’s test, power one test, and a MOSUM test (e.g., Picard (1986);

Johnston et al. (1987)).

• With respect to “safeguards significance” as it pertains to trend analysis, a trend should be 

considered significant when the applied test indicates it to be so and the absolute quantity 

involved is in excess of 3 FKG.

• To select a trend analysis test, the licensee should evaluate historical data to determine 

whether the assumptions of the statistical test are appropriate, including distribution of data 

and independence of successive data.
19 NUREG-1280, Revision 2

• Two process difference estimates in succession within the same process control unit that 

exceed three times the standard deviation of their estimators and their sum exceeds 3 FKG, 

where both suggest a loss or a gain, should trigger additional investigative measures that 

include the following:

− notification of the nuclear materials control manager

− review of security records

− added surveillance measures in the involved process unit

− conduct of a physical inventory of the associated material balance area (MBA) within 

2 months

3.7 Research and Development Operations

The MC&A plan should provide the criteria that are used to define a lot or batch for R&D 

operations.

The plan should describe how the components of a process material balance are established,

including the degree to which a process will be cleaned out or holdup measurements will be 

performed. The plan should discuss the handling of scrap, including measurement, 

pretreatment before recovery, and segregation.

Acceptance Criteria:

• Proposed materials groupings into lots or batches are acceptable taking into account prompt 

loss detection objectives, measurement characterization, and processing constraints.

• For R&D material balances, the inputs to the SEID are reasonable and include all sources of 

measurement error.

• IDs on R&D lots or batches generated during an inventory period may be based on weight 

comparisons provided that the following is true:

− The lots or batches represent intermediate products.

− The input materials to the R&D facility are measured for element or isotope, or both.

− No credible substitute materials are present in the MAA, or adequate controls exist to 

preclude the use of substitute materials to conceal a diversion.

− The quantity of SSNM in sidestreams can be reliably measured.

− The ultimate product of the operation is measured for element or isotope, or both, as 

appropriate.
NUREG-1280, Revision 2 20

3.8 Commitments and Acceptance Criteria

In its MC&A plan, the licensee should provide definitive commitments that adhere to the 

regulatory requirements and meet acceptance criteria applicable to process monitoring. A 

finding that the licensee’s MC&A plan for conducting process monitoring is acceptable and in 

accordance with 10 CFR 74.53 will be based on, but not limited to, the acceptance criteria listed 

in Sections 3.1 through 3.7 above.
21 NUREG-1280, Revision 2

4. ITEM MONITORING

4.0 Regulatory Intent

The intent of the 10 CFR 74.55 item monitoring requirements is to ensure timely plantwide 

detection of the loss of items that total 5 FKG or more. To achieve this capability, the licensee 

is expected to verify the presence and integrity of selected SSNM items on a periodic basis. 

The required frequency of tests for missing items is graded according to the relative 

attractiveness of the material type in the item, the ease with which the item could be diverted 

without being observed, and the degree of surveillance and containment provided for by the 

material control and physical security systems. Under 10 CFR 74.55(a), SSNM is not 

considered as being in item form unless it falls into at least one of the following categories:

(1) It is encapsulated.

(2) It is within a tamper-safe sealed container.

(3) It is stored within a vault.

(4) It is stored in a controlled access area (CAA) that is permanently controlled and which

provides protection at least equivalent to tamper-safing.

(5) It is contained in samples each containing less than 0.05 FKG.

If SSNM is not in item form, it must be subjected to the in-process control requirements for bulk 

material described in 10 CFR 74.53 (except for the types of material specified in the

10 CFR 74.53(a)(2)–(4) exceptions). The longer detection times for losses of items from 

permanently CAAs take into account the added security afforded by the physical protection 

measures required for CAAs by 10 CFR Part 73. However, this provision should not be 

interpreted as authorizing the placement of materials in permanently CAAs other than those 

already authorized under 10 CFR Part 73.

4.1 Item Loss Detection

As required by 10 CFR 74.55(b), each licensee must establish the capability to detect a 5 FKG 

or greater loss in item form using any statistical test that has a 99 percent power of detection. 

Detection is to occur within the following timeframes:

• 30 calendar days of a Category IA loss and 60 calendar days of a Category IB loss for 

those items in a vault or permanently CAA isolated from the rest of the MAA 

(10 CFR 74.55(b)(1))

• 3 working days of a Category IA loss and 7 calendar days of a Category IB loss for items 

located elsewhere in the MAA except that a 5 FKG or greater loss of encapsulated 

SSNM components that are each at least 1 meter in length and in excess of 

30 kilograms is to be detected within 30 calendar days (10 CFR 74.55(b)(2))

• 60 calendar days for the loss of Category IB items of waste stored in a permanently CAA 

outside of an MAA (10 CFR 74.55(b)(3))
NUREG-1280, Revision 2 22

• 60 calendar days for samples in a vault or permanently CAA and 30 calendar days for 

samples elsewhere in the MAA for those samples that each contain less than 0.05 FKG 

of SSNM (10 CFR 74.55(b)(4))

In accordance with 10 CFR 74.55(a), licensees must ensure that items are uniquely identified

and quantitatively measured, with the validity of the measurement independently confirmed. 

Additionally, items are to be handled in either of the following ways:

(1) tamper-safed or placed in a vault or permanent CAA that provides protection at least 

equivalent to tamper-safing

(2) sealed such that removal of SSNM would be readily and permanently apparent (e.g., 

encapsulated)

As stated in 10 CFR 74.55(c), items containing scrap in the form of small pieces, cuttings, chips, 

solutions, or in other forms that result from a manufacturing process, held in containers of 

30 gallons or larger, with an SSNM concentration of less than 0.25 grams per liter, are excepted

from the 10 CFR 74.55(b) requirements.

4.2 Item Identification and Classification

The applicant or licensee should describe the identification system (numeric or alpha numeric) it 

uses to assign identification to each item. The description should include the features of the 

system that preclude falsification or that ensure prompt detection of such attempts.

The applicant or licensee should state that the overall MC&A program maintains a record of all 

SSNM items, regardless of quantity or duration of existence. In addition, the item monitoring 

component of the MC&A program should provide current knowledge of the location, identity, 

and quantity of all SSNM contained in all items that are not excepted from the item monitoring

requirements (examples of such excepted items are containers of waste designated for burial or 

incineration). 

Each item that is not excepted from the item monitoring requirements should be stored and 

handled in a manner that enables detection of, and provides protection against, unauthorized or 

unrecorded removals of SSNM. All items, whether or not they are subject to item monitoring

coverage, should have a unique identity. For items subject to the item monitoring requirements, 

the following means are acceptable for providing unique identity:

• a unique alpha-numeric identification on a tamper-indicating device (TID) applied to a 

container of SSNM

• a unique alpha-numeric identification permanently inscribed, embossed, or stamped on 

the container or item itself

• a uniquely prenumbered (or barcoded) label applied to each item having good adhesive 

qualities such that its removal from an item would preclude its reuse

Location designations shown by the MC&A records need not be unique, but location

designations should be specific enough so that any item may be located within 1 hour. Longer 

times may be acceptable but should be further justified in the MC&A plan. The licensee should 
23 NUREG-1280, Revision 2

control the MC&A record system in such a manner that the record of an item's existence cannot 

be destroyed or falsified without a high probability of detection. Each nonexempt item should be 

stored and handled in a manner that enables detection of, and provides protection against, 

unauthorized or unrecorded removals of SSNM.

The MC&A plan should provide the basis for classifying items as material Category IB and any 

proposed exemptions from item monitoring tests or from response actions, including a listing of 

the item categories involved and the rationale for such exemptions.

The MC&A plan should identify the item locations within the facility classified as inaccessible 

(relative to item accessibility by a single individual). The plan should also provide the 

justification for classifying an item location as inaccessible and any proposed exemptions from 

item monitoring tests. The licensee must be able to detect losses from any location. The 

concept of accessible location applies to the criteria for establishing and determining the 

timeliness of the licensee’s detection capabilities. 

Acceptance Criteria:

• Each SSNM item is uniquely identified; the SSNM content is quantitatively measured; the 

validity of the measurement is independently confirmed and ensured through encapsulation, 

tamper-safing, or storage in a vault or permanently CAA that provides protection at least 

equivalent to tamper-safing; and a record of the identity, location, date of creation, SSNM 

content, and utilized measurement method is maintained.

• Items are classified as either Category IA or IB at the time they are created so as to fix the 

frequency of tests for item loss.

• All items not included in process monitoring will be included in the sample population 

stratification for item verification, unless exempted by 10 CFR 74.55(c). The appropriate 

power of detection and verification frequency will be used, based on category and specific 

item characteristics.

• For items not exempted from the item monitoring program, a record system is maintained to 

provide knowledge of the current status of such items. For items subject to this 

commitment, the item control and records system provides the capability to promptly locate 

and confirm the existence of any specific item or group of items upon demand. The item 

record system is secured in such a manner that a single individual cannot destroy or falsify 

the record of an item’s existence without a high probability of detection.

• Each item (unless it is an exempted item) is stored and handled in a manner that enables 

detection of or provides protection against unauthorized or unrecorded removals of 

SNM/SSNM; otherwise, knowledge of the SNM/SSNM content is assured by TIDs or 

maintaining the item as a sealed source (i.e., as encapsulated material).

• All incidents involving missing or compromised items or falsified item records are 

investigated. (A compromised item is one for which there is evidence of tampering or which 

is found outside its assigned CAA.)
NUREG-1280, Revision 2 24

• The contents of a compromised item or an unsealed, unencapsulated item located after it 

has been missing will be redetermined by measurements (i.e., by NDA or by weighing, 

sampling, and analysis).

• The item identification system possesses attributes that ensure unique item identification, 

preclude falsification, or at a minimum, make prompt detection of such attempts highly 

probable. The following factors should be considered in achieving this objective:

− The use of TID numbers for unique identification represents an attractive alternative 

because the same number is used for both TID and item tracking, TID numbers cannot 

be altered without leaving visible evidence, and TID distribution and usage are 

controlled.

− The use of prenumbered containers that retain the same identification for repeat uses 

should generally be avoided unless detailed usage records are maintained that reflect 

the source and disposition of items, including times to fractions of a day.

− The use of preprinted labels or blank labels that are numbered as they are used is 

acceptable provided that unauthorized alteration or replacement of the labels would be 

readily apparent to a knowledgeable observer.

• The methods used to classify items are consistent with those defined in Section 3.2 of this 

document for process monitoring. The record system identifies whether an item has been 

classified as Category IA or IB.

4.3 Accessibility and Storage Controls

The MC&A plan should describe the personnel access controls, the surveillance procedures, 

and the records procedures for entrance and exit of personnel to and from vaults and 

permanently CAAs. If the facility’s physical security plan describes any of the above attributes 

in sufficient detail, appropriate references may be made.

The MC&A plan should fully describe item storage areas and controls. In particular, the plan 

should discuss in detail the controls that are used as the basis for ensuring the values of prior 

measurements, as opposed to remeasuring the item at inventory time, and explain the rationale 

for accepting prior measurements. Any controls used to ensure the validity of prior 

measurements should be equivalent to the protection provided by tamper-safing, which is 

defined by 10 CFR 74.4 as the use of devices on containers or vaults in a manner and at a time 

that ensures a clear indication of any violation of the integrity of previously made measurements 

of the SSNM in the container or vault.

Both administrative controls (e.g., custodian assignments and limiting authorized access to 

storage areas) and physical controls (e.g., locked or alarmed doors) should be identified.

Acceptance Criteria:

• Storage that meets the physical security requirements for vaults, documented in 

10 CFR Part 73, will meet the requirements of 10 CFR 74.55 for storage of items containing 

either Category IA or IB material.
25 NUREG-1280, Revision 2

• Vaults or permanently CAAs that are subject to 30-day (Category IA) or 60-day 

(Category IB) test frequencies and isolated from the rest of the MAA are operated with 

physical and administrative controls over personnel access such that the unauthorized 

addition and removal of items from the storage area will be either prevented or promptly 

detected.

• Storage that meets the following requirements is acceptable as a CAA, isolated from the 

rest of the MAA for the purposes of 10 CFR 74.55:

− The CAA is constructed or equipped with physical protection capabilities that deter and 

detect unauthorized access.

− Access to the storage area is limited to the minimum number of persons necessary, and 

records are kept of the persons who enter and leave it.

− Records of the items in storage are maintained.

− An individual within the storage area is continuously observed by another person, and all 

additions, removals, and movements of material are verifiable by at least two individuals.

• Storage provides protection at least equivalent to tamper-safing if it meets the following 

conditions:

− Access to the vault or CAA is limited to the minimum number of persons necessary, and 

records are kept of the persons who enter and leave it.

− The personnel authorized to enter and operate the vault or CAA are not authorized to 

remove or handle SSNM beyond the boundaries of the vault or area unless controls are 

in place that would preclude an individual from surreptitiously removing an item or any 

portion of a nontamper-safed container.

− At all times, a person within a vault or permanently CAA is accompanied by at least one 

other person, and all activities by any person are verifiable by another. In addition, 

remote surveillance, such as closed-circuit television, with the capability of seeing all 

operators at all times is used. The remote surveillance need not be continuous if the 

occupants cannot determine or predict when they may be under surveillance. However, 

the time of remote surveillance should, on the average, equal at least 25 percent of the 

nonsurveillance time, and any interval of nonsurveillance should not exceed 5 minutes.

− The SSNM content of nontamper-safed and unencapsulated items is measured and

independently confirmed by a second person. In addition, the item is under the 

continuous surveillance of the two persons from the time of measurement until placed in 

a vault or CAA.

− The SSNM contents of nontamper-safed and unencapsulated items are verified by 

quantitative measurements when removed from a vault or CAA, except for solid 

components which can be verified by a weight check. The verification measurement is 

equivalent to (or better than) the original measurement in terms of measurement 

uncertainty. The verification measurement and the original result agree within the 

combined measurement uncertainties. (Note: Random errors will generally be the only 
NUREG-1280, Revision 2 26

component of the uncertainty, except in those instances in which a recalibration of the 

measurement process has taken place.) The verification measurement also detects 

substitution unless it can be demonstrated that no credible substitute material is present 

in the vault or CAA.

− The response actions documented in the licensee’s MC&A plan are initiated if an 

unauthorized vault or CAA penetration is known or suspected to have occurred or if the 

SSNM content of any container is unexplainable and differs significantly from the 

recorded value.

4.4 Accounting and Control Procedures

The MC&A plan should describe the item accounting and control procedures for items placed in 

and removed from secure storage. The description should include the item inventory records 

utilized.

Acceptance Criteria:

• Procedures approved by the MC&A organization are utilized and reviewed annually for all 

secure storage areas.

• Each procedure should designate the individual responsible for that secure storage area 

and describe the method and inventory records used for documenting additions or 

withdrawals of items from the area.

• The operating procedures of item storage areas are documented.

• Every change of inventory in the storage area is recorded.

• A designated individual is responsible for the operation of each such storage area.

• The response actions documented in the MC&A plan will be initiated if one or more items 

are missing, except when the missing items total less than 50 grams of U-235, U-233, or 

plutonium.

4.5 Item Measurements

The MC&A plan should identify and describe the measurement systems used to quantify the 

SSNM content of items at the time of their creation. The description should include the 

confirmatory measurements used to quantitatively verify the SSNM content of nontamper-safed 

and unencapsulated items placed into or removed from vault storage or a CAA that is equivalent 

to tamper-safing, including the controls that prevent or detect attempts at substitution.

Acceptance Criteria:

• Accountability and confirmatory measurement systems are identified and described in

written procedures.

• Independent confirmation of the SSNM content of items may be achieved by having a 

second person do the following, as appropriate:
27 NUREG-1280, Revision 2

− Observe the bulk measurement and sampling of the item whose contents are to be 

determined.

− Observe the NDA of the item.

− Perform a second quantitative analysis independently that does not destroy the integrity 

of the item.

− Witness and attest to the application of an approved tamper seal.

− Accompany the first person and the item to a vault or permanently CAA which will 

provide storage equivalent to tamper-safing.

4.6 Item Verification

The MC&A plan should describe the item verification procedure. The description should include

the following:

• the inventory sampling method, including the sample size selection equations, the item

stratification plan, and the method of selecting the actual items to be verified

• the extent to which cyclic, dynamic, or perpetual inventory data and production records, 

if any, will be used to modify or supplement the sample size, sample selection, or item 

verification procedures

• the minimum loss detection sensitivity and maximum time periods between item 

verifications for each item stratum of material

The annex to the MC&A plan should provide the rationale for the item stratification plan.

Acceptance Criteria:

• When incorrect descriptive information for an item, such as item type, TID number, or 

location, is discovered, the action to be taken will ensure that the item is located and

correctly identified and that deficiencies in the system are corrected.

• In addition to positive identification and location confirmation, item verification includes 

encapsulation integrity or container integrity checks, as appropriate; and TID integrity 

checks, if appropriate. Considerations related to verification include the following:

− Electronic or optical methods such as bar code readers may be used in place of manual 

methods to record item or seal numbers, provided safeguards against falsification are in 

place.

− If the licensee can demonstrate that seal falsification is not credible, TID identification 

can be done on a random basis, provided an independent means of confirming item 

identity, such as unique container numbers, is utilized.

− TID integrity checks normally encompass visual examination and, for certain TIDs (e.g., 

Type E), physical handling. Proposed shortcuts may be justified on the basis of low 
NUREG-1280, Revision 2 28

strategic value, limited accessibility, frequency of checks, and backup checks by 

production, quality assurance, production control, or others. Such shortcuts should be

reviewed for acceptability on a case-by-case basis.

− The magnitude of the formal item verification effort can be adjusted to take credit for 

other means of confirming the presence and identity of sealed items. Process control 

and accounting, quality control testing, and other production operations routinely 

generate information that can serve to verify the identity and presence of sealed items. 

These sources can be used in lieu of item verification, provided the frequency and loss 

detection sensitivity requirements of the item verification procedure are met and the use 

of the data for this purpose is not predictable. Examples of specific sources of such data 

include the following:

• records that an item was created (tamper-safing procedure applied) or transferred 

within the required time span, as defined in 10 CFR 74.55(b)

• records that an item was inspected, tested, analyzed, altered, or subjected to any 

other production or quality assurance operation within the required time span

• production schedules showing that a particular item was “cued up” for production 

planning purposes and the cueing process involved a check of identity and location

− Any tamper-safe or encapsulated items that have been verified by such a procedure 

within the time span required for that category of material can be exempted from formal 

item verification, provided (i.e., only if) the prior handling or inspection activities, as 

indicated above, for which credit is being taken are unknown and unpredictable to a 

potential diverter or, if known or predictable, the items are scheduled to be physically 

accounted for by at least two individuals during sequential processing or inspection 

steps to occur during the next required test time span. To exempt such items from 

formal item verification, the items are simply dropped from the list of n items selected 

from the inventory list, where n is the sample size required for verification.

− The frequency of item verification tests is consistent with the maximum elapsed time 

intervals between the occurrence of a loss and its detection, as specified in 

10 CFR 74.55(b).

• A physical inventory can serve in lieu of an item monitoring test, provided all items 

represented by an item test are subject to verification as part of the physical inventory 

process and the following applies:

− By using the physical inventory in lieu of item monitoring tests, there is no extension in 

the maximum time interval between item monitoring tests for 3-day and 7-day tests.

− For 30-day and 60-day item tests, the physical inventory is completed within 33 calendar 

days and 66 calendar days, respectively, of the previous item test.
29 NUREG-1280, Revision 2

4.7 Sample Items

The MC&A plan should describe the technique used to establish the sample population and 

demonstrate how the presence of selected items will be verified. Additionally, the plan should 

describe how samples containing greater than 0.05 FKG will be monitored.

Acceptance Criteria:

• Samples containing in excess of 0.05 FKG can be considered a sidestream in a bulk test 

performed in the originating process unit, provided the samples are returned to process 

within 7 days. SSNM removals from such samples should be documented and the area 

records corrected accordingly.

• Small items, such as element sections and samples, can be amassed in a tamper-safed 

container to alleviate excessive item verification. Conversely, items greater than 0.05 FKG 

should not be consolidated within a larger tamper-safe container for the primary purpose of 

reducing item verification effort.

• The means of determining the number of items to be verified per class or stratum is 

specified. For example, the following equation is an acceptable formula for calculating the 

sample size required from an inventory or any subset of group of size N:

n = N (1 β1/d) or n = N (1 βx/G),

where d is the minimum number of altered or missing items (defects) that could total a 

goal quantity (i.e., 5 FKG) and 1 - β is the desired probability of obtaining at least one 

defect in the sample of n items where there are d defects (d is greater than or equal to

one) in the population of N items. The number d is a function of the amount of SSNM 

per item. If the SSNM content varies over the population of items, the largest value must 

be used to calculate d to ensure that n is large enough to guarantee that the power of 

detection is at least 99 percent. This results in a conservative value of n (i.e., n is larger 

than necessary). If a smaller item content were chosen, such as the average value, an 

informed adversary could selectively divert only large items and thereby reduce the risk 

of detection. The 1/d exponent is equivalent to x/G (as shown in the alternative 

equation), where x is the maximum formula grams within a single item (for the stratum 

being tested) and G is the goal quantity.

• Additional points to consider in this regard include the following:

− In those cases in which the SSNM content per item is very small, the required sample 

size is a small fraction of the inventory. The result may even be that, in some instances,

the calculated sample size will be less than one. However, such items cannot be 

ignored. An acceptable approach would be to periodically verify one randomly selected 

item from the class at times chosen by random selection, such as by a random number 

generator.

− In some instances, an entire stratum may contain less than 5 FKG. Nevertheless, such 

strata should be sampled like any other.
NUREG-1280, Revision 2 30

− If the number of items, N, in each strata remains reasonably constant (such as within 

95 to 105 percent of an historical average N), it is not necessary to recalculate the 

fraction of the population, n/N, to be checked each time.

− Neither the specific items to be verified in any particular instance nor items that will not

be verified shall be predictable.

− Every item in a stratum has an equal probability of being selected for verification.

• Items of Category IA type material may be treated as Category IB items and subject to the 

lower frequency item loss test if any of the following conditions apply:

(1) The item is rigid and its dimensions are large enough to preclude hiding the item on 

an individual (i.e., at least 130 centimeters in one dimension, greater than 

65 centimeters in each of two dimensions, or greater than 20 centimeters in each of 

three dimensions).

(2) The weight of an item is so large that one person cannot carry the item 

inconspicuously. The minimum weight to meet this criterion is 50 kilograms.

(3) The quantity of SSNM in the item is so small that a large number of diversions are 

needed to accumulate 5 FKG. The maximum quantity to meet this criterion is 

50 formula grams per item.

The first two exceptions (for item test frequency) given above do not apply if the item can be 

opened or disassembled and part or all of the SSNM removed without a high probability of 

being observed or detected.

• The presence of very large (higher tier) components, such as fuel blocks, preassemblies, 

and subassemblies, stored outside of a CAA must be verified in accordance with a sampling 

plan that provides the capability to detect a 5-FKG loss within 30 calendar days. One month 

is deemed to be acceptable on the basis of the large physical size and weight of these items 

and the restrictions on removing them from the MAA.

• The number of items to be verified is sufficient to provide a power of detection of at least 

99 percent for a loss of items totaling 5 FKG or more from each stratum or inventory

subdivision (i.e., a grouping into similar types and amounts of SSNM). If all strata in a 

facility are sampled for verification with at least a 99-percent power of detecting a loss of 

items containing 5 FKG, that criterion will also be achieved for a loss of items containing 

5 FKG or more plantwide.

• The item inventory is stratified or subdivided in a manner that ensures at least a 99-percent

power of detection while minimizing the number of items to be verified. It is advantageous 

to subdivide the inventory into classes or strata having approximately uniform quantities of 

SSNM per item. A moderate range of SSNM contents within a class, such as plus or minus

10 to 20 percent is tolerable. However, regardless of the variability of SSNM content per 

item, the maximum item content (for the stratum in question) must be used when 

determining the minimum number of items that could constitute a 5-FKG loss (and hence 

determine the number of items that make up the sample size, n). Typical classes for 

sampling are fuel elements, containers of scrap, containers of feed material, and containers 

of waste.
31 NUREG-1280, Revision 2

• Encapsulated items containing less than 100 grams of SSNM whose presence has been 

verified during the prior 2 months as part of a statistical sample or handling during routine 

production need not be reverified for physical inventory. Items whose presence has not 

been verified in the same time interval should be located by two-person inventory teams.

• Whenever an item monitoring test results in an MC&A alarm, a 5-FKG (or greater) loss 

should be assumed until shown otherwise either by additional (i.e., extra) item monitoring 

tests or by a physical inventory. Section 3.0 of this document defines an item monitoring 

alarm. When verifying n randomly selected items for an item test, if one or more defective or 

missing items are encountered, an additional group of randomly selected items from the 

same stratum should be tested. In this additional test, the sample size should be twice as 

large (i.e., equal to 2n) and should not include any defective items from the initial test. Other 

strata scheduled for testing on the same date as the stratum giving rise to the alarm should 

also be subjected to additional testing (by using a sample size of 2n instead of the normal 

size of n items). If the quantity of missing SSNM associated with the initial alarm is 

substantially less than 5 FKG and no further alarms result from the additional tests, strong 

evidence will have been obtained that a 5-FKG loss did not occur. If, on the other hand, one 

or more additional alarms are encountered, a complete physical inventory of all SSNM items 

should be immediately initiated. 

4.8 Commitments and Acceptance Criteria

In its MC&A plan, the licensee should provide definitive commitments that adhere to the 

regulatory requirements and meet acceptance criteria applicable to item monitoring. A finding 

that the licensee’s MC&A plan for conducting item monitoring is acceptable and in accordance 

with 10 CFR 74.55 will be based on, but not limited to, the acceptance criteria listed in 

Sections 4.2 through 4.7 above.

33 NUREG-1280, Revision 2

5. ALARM RESOLUTION

5.0 Regulatory Intent

The intent of the 10 CFR 74.57 alarm resolution requirements is that a licensee resolve the 

nature and cause of any MC&A alarm within an approved time period, or if not resolved within 

the approved time period, the licensee must notify the NRC that the alarm in question remained 

unresolved beyond the time period specified for its resolution. The regulations in 

10 CFR 74.57(c) require that such notification occur within the 24 hours following the expiration 

of the resolution period, except when a holiday or weekend intervenes, in which case the 

notification must occur on the next scheduled workday. If a loss has occurred, 10 CFR 74.57(d) 

requires the licensee to determine the amount of SSNM lost and, as appropriate, return 

out-of-place SSNM to an appropriate place, update and correct involved records, and modify the 

MC&A system to prevent similar occurrences in the future. Additionally, if a process monitoring 

abrupt loss detection estimate exceeds 5 FKG of SSNM, 10 CFR 74.57(f) requires that material 

processing operations related to the alarm be suspended until completion of planned resolution 

activities, unless the suspension of operations will negatively affect the ability to resolve the 

alarm. However, operations of continuous processes may continue for a 24-hour period while 

checks are made for mistakes.

The intent of these requirements is that the licensee’s alarm resolution system must be able to 

respond promptly to alarms indicating a potential loss of SSNM and determine whether the 

alarm was caused by an actual loss or by a system error. The alarm resolution program also 

should be able to identify the type of system error or innocent cause so that remedial action can 

be taken. The alarm response should be timely to ensure that alarms are investigated and 

resolved promptly while memories of events leading up to the alarm are still fresh, materials are 

still available for remeasurement, and fewer changes of process conditions, inventories, 

in-process holdup, and item locations will have occurred. Prompt resolution will facilitate 

recovery of lost or stolen material.

For process monitoring, an MC&A alarm is defined as any material control test result that 

exceeds a defined alarm threshold value such as that given in Section 3.2 of this document.

For item monitoring, an MC&A alarm exists whenever an item monitoring test results in (1) one 

or more item discrepancies (i.e., items not in their designated locations) which are not resolved 

within 8 hours for Category IA items and 24 hours for Category IB items or (2) one or more 

items being found defective (i.e., with some or all of their SSNM contents missing).

5.1 Alarm Resolution Procedures

The MC&A plan should describe the alarm resolution procedures that will be applied to the 

various types of alarms and unit processes. The procedures should take into account credible 

innocent occurrences that may cause alarms indicating a potential SSNM loss. The resolution 

procedure descriptions may be abbreviated.

The plan should describe the specific procedures to be employed in response to alarms 

indicating a potential loss in excess of 5 FKG. The description should identify those operations 

that will be shut down or alternative measures that will be employed in lieu of shutdown to 

facilitate an investigation.
NUREG-1280, Revision 2 34

The annex to the MC&A plan should provide the following:

• a listing of identified credible causes of possible alarms by unit process and details of the 

resolution procedures by which specific causes could be identified

• a statistical estimate of the expected number of irresolvable alarms per inventory period 

with loss estimates greater than 5 FKG and a description of the estimation method

• the justification for not shutting down certain process operations during an investigation

Acceptance Criteria:

• Resolution procedures are described for alarms that indicate a potential abrupt loss of 

5 FKG of SSNM in bulk or item form. The procedures should take into account the expected 

differences in loss mechanisms and necessary differences in response approaches for inprocess materials, items, different material types, and different types of unit operations. The 

differences and variations in resolution procedures are explained. Examples of different 

types of unit processes include the following:

− a bulk storage unit

− a batch process with cleanout between batches and very small amounts of in-process 

holdup

− a continuous process with continuous flow between the unit process and the succeeding 

process

− a process with large holdup inventories that cannot be measured directly without 

cleanout

• The alarm resolution procedures provide a systematic and logical sequence of steps for 

determining the cause or causes of an alarm. The following are examples of a systematic 

approach:

− Check the data and calculations for clerical, transcription, or computational errors.

− Trace the data to the primary sources (operator logbooks or production records and 

analytical reports) to check for agreement.

− Compare the source data, such as item and batch sizes and numbers, inventory 

quantities, and flow rates, to historical values to detect anomalies that may indicate an 

error of identification or measurement.

− Review downstream material balances for potential offsetting gains.

− Localize the source of the alarm as nearly as possible with regard to time, place, 

material type, and individuals potentially involved.

− Report a potential SSNM loss to security who then should implement intensified search 

and surveillance procedures.
35 NUREG-1280, Revision 2

− Stop further processing in the unit process, if feasible, to retain items and inventory for 

remeasurement.

− Remeasure all items, inventories, batches, and samples from the unit process that are 

still available.

5.2 Types of Alarms

The MC&A plan should describe the types of information and data developed during response 

that will provide sufficient evidence for assigning a specific cause to an alarm. This information 

and data should form the basis for development of the decision rules to be included in this 

section. These rules should take into account every identified potential innocent cause that may 

result in a bulk or item loss alarm.

Acceptance Criteria:

• Each type of alarm response is identified with the corresponding types of material or unit 

processes, or both, and the credible innocent causes of the alarm. Examples of innocent

causes include the following:

− A clerical or computational error is identified that clearly explains the alarm.

− A missing item is located.

− A claim is made that an item was added to the process, although no record of the 

transfer exists, if substantiated through an actual yield versus predicted yield 

comparison.

− A remeasurement confirms that an error or errors in the original data caused the alarm.

− A random fluctuation in the measurement process or a process variability is identified 

through sufficient measurements or additional processing.

• The decision rules for a conclusion that a particular cause is applicable and that the alarm is 

resolved are described. The annex to the MC&A plan includes backup information about 

the rationale and justifications. A decision rule should generally provide an objective basis 

for deciding whether or not the data and information acquired up to that point in the alarm 

assessment supports the hypothesis that the alarm resulted from an innocent cause. Each 

decision rule should be based on the identification of a specific cause or a source of 

incorrect data that contributed to the alarm level of the loss estimator, except that the rule 

may verify with high probability that no loss has occurred without having identified all

contributing causes of the alarm. Examples of acceptable decision rules include the 

following:

− a false alarm resulting from a mistake

− a correctable mistake identified and supported by direct evidence, such as comparison 

to data collection sheets, reading a column level, or measuring a sample
NUREG-1280, Revision 2 36

− a correctable mistake or recordkeeping error identified and supported by at least two 

sources of independent indirect evidence, such as consistency of process values, 

historical ranges, a loss followed by a gain in the following control unit such that an error 

in the transfer was identified as greater than measurement error, or an interview with 

operators who observed an unusual process condition

− a hypothesized uncorrectable mistake (or combination of mistakes) or procedural error 

which is supported by a difference of opposite sign and comparable magnitude in a 

related loss indicator and two sources of indirect evidence, such as process yield, 

balance around non-SSNM materials, process consistency, or measurement control 

data indicating a short-term failure

− a false alarm caused by stochastic fluctuations in the detection system

− an error resulting from measurement variability identified and supported by remeasuring 

inventories or transfers where the differences between the original and remeasurement 

values exceed the 2-sigma confidence interval used to monitor and control 

measurement performance

− an error resulting from variabilities in the process that is confirmed by processing the 

material and verifying the discrepancy by recovering the material

− an error resulting from inadequate modeling of in-process inventory where continued 

processing results in a stable cumulative loss indicator

− a bias identified by an independent technique that results from differences in material 

types being processed

• A systematic investigation into the nature and cause of each MC&A alarm will continue until 

the cause has been established or a determination has been made that the alarm is not 

resolvable with the information currently available.

• Remeasurements of the SSNM to verify the content or composition of items or bulk material 

associated with an alarm are made to a standard deviation of the quantity estimate that is 

comparable to that of the book value, and the hypothesis that the difference between the 

initial and remeasurement value is zero is tested at the 0.05 level of significance.

• After an alarm has been resolved, the planned corrective action includes MC&A system 

revisions, if appropriate, that provide reasonable assurance that future alarms of that nature 

(i.e., having the same or a similar cause) will not occur. An example of a case in which an 

MC&A system revision would be appropriate would be revision of a procedure or computer 

software that contains an error that caused an alarm.

• The operations that will be shut down to resolve alarms indicating a possible loss in excess 

of 5 FKG are identified or alternatives to shutdown are provided. (Refer to Section 3.2 of 

this document for establishing alarm threshold values indicative of a possible 5-FKG loss.)

Examples of acceptable alternatives might include the following:

− shutting down of only downstream operations to retain products that may require 

remeasurement
37 NUREG-1280, Revision 2

− discontinuing the processing of certain sidestreams to retain scrap or recyclable 

intermediates that may require remeasurement

− diverting scrap, waste, or product from the alarming unit to auxiliary vessels or to a 

buffer storage area to retain the products for remeasurement

− collecting additional samples for remeasurement of materials that would become 

unavailable if operations were not suspended in the area under investigation

• When a detection alarm indicates a potential loss in excess of 5 FKG, batch processing 

operations are suspended immediately after the alarm or upon completion of the batch in 

process, and the suspension is continued until completion of the planned resolution 

activities.

• When a process is not shut down, equally effective alternative measures are taken when an 

alarm occurs to protect information and material that would be needed during the alarm 

investigation. Procedures document alternative measures by unit process.

• The key consideration in employing alternatives to shutdown is that the licensee can show 

that no data or information needed for response will be lost if the alternative is used.

• The conditions for restart are specified. Fundamental to any decision to restart is whether 

the alarm has been resolved (i.e., an assignable cause has been identified), the loss is real 

but remedial, recovery action is underway, or the alarm has not been resolved. Before

restart, the licensee should verify that all possible data associated with the process material 

have been acquired, and no information will be jeopardized by resuming operations.

• The quality of the licensee’s loss resolution capability is such that the combination of the 

material control test and resolution decisions permit alarms remaining unresolved after 

investigation to be good indicators of material loss. To achieve this objective, the licensee’s 

planning data should demonstrate that the expected number of unresolved alarms in excess 

of 5 FKG is less than 0.10 abrupt loss alarms per inventory period.

The following additional information is pertinent to this point:

• The only false alarms that should be predicted are those associated with normal process 

or measurement system statistical variation. Mistakes in transcription of data or process 

upsets do not need to be predicted because the response procedures should be 

designed to correctly resolve alarms stemming from those types of events. False alarms 

caused by statistical fluctuations are expected to be more difficult to resolve.
NUREG-1280, Revision 2 38

• One approach is to claim no credit for resolution of statistical alarms. Then the 

incremental expected number of alarms with discrepancies greater than 5 FKG can be 

calculated for a single test from the formula:

∆N = 1 F (5/σ)

where

σ = the predicted standard deviation of the detection test in FKG

F(x) = the predicted statistical distribution of the test statistic normalized by σ

This increment should then be multiplied by the expected number of times the test will be 

performed in an inventory period and similar calculations then added up over all tests in the 

facility. That sum must be less than 0.10 (i.e., the number of such alarms would be less than 

one in 60 months, assuming a physical inventory frequency of every 6 months).

If the distribution function cannot be assumed to be normal (Gaussian) and the true distribution 

cannot be adequately predicted, the Camp-Meidell inequality may be applied if it is reasonable 

to expect that the true distribution will be symmetric and unimodal (see Shewhart (1931), 

pages 176–177; Eisenhart, Hastay, and Wallis (1947), page 49). The Camp-Meidell inequality 

permits a bound on N to be calculated from the following formula:

∆N ≤ ( ) ( )

2

where σ is expressed in units of FKG. However, this will typically be useful only if σ is less than 

0.1 FKG. A more useful approach would be to estimate the maximum range for the test statistic 

based on a physical model of the process and measurement systems under the hypothesis of 

no material diversion. If this value is less than 5 FKG, set ∆N = 0.

Evaluation is more complicated if the licensee claims that response procedures will permit 

resolution of some fraction of the statistical false alarms. The plan should summarize such 

procedures. One evaluation approach is to make additional measurements of inputs, products, 

sidestreams, and holdups to complete measured material balances when loss detectors are 

based on average expected yields. For additional measurement of input quantities, samples 

should be taken and retained. This would permit laboratory analyses to be made which are 

more reliable than NDA. The procedures also could utilize data resulting from processing the 

same batch through the next process step, data resulting from processing another batch 

through the same process step, and tests that eliminate intermediate measurement points by 

combining several process steps. In any of these, estimating the fraction of N that would be 

expected to remain unresolved will likely involve detailed modeling of the response capability.

A Monte Carlo simulation method can be used to model the alarm response procedures and 

predict the resolution success rate. For a single material control test, refer to Tanner (1981). 

For an entire plant, refer to Reardon, Heaberlin, and Eggers (1982). Eggers (1982) also 

provides detailed information.
39 NUREG-1280, Revision 2

Alternatively, if the licensee has a performance history of responses to and assessment of 

alarms, this may be cited in lieu of the simulation of a proposed response program, if the 

experience demonstrates a capability to meet the commitment goals for resolving false alarms.

The combined quality of the material control test and loss resolution decisions should permit 

alarms remaining unresolved after completion of the licensee’s investigative activities to be 

good indicators of theft or diversion. This will be evaluated in two ways:

(1) During the NRC staff review of a licensee’s planned detection and alarm resolution 

capabilities, attention will be directed to the ability to resolve false abrupt loss alarms. 

For the alarm resolution capability to be acceptable, it should appear able to correctly 

identify all errors caused by leaks, process upsets, or human mistakes that are large 

enough to cause an alarm. With respect to other false alarms, in particular those alarms 

that are expected to occur because of the statistical nature of the processes and 

measurement systems, the alarm resolution capability need not be 100-percent

effective. However, for it to be acceptable, it must be effective enough to satisfactorily 

limit the statistically expected rate of irresolvable abrupt loss alarms. (The expected rate 

can be thought of as a weighted average of all possible rates, where the weights are the 

likelihoods of occurrence of those rates.) A satisfactory limit is an expected rate of 

irresolvable large abrupt loss alarms less than one per 10 years per plant. A large false 

alarm is one whose loss estimate exceeds 5 FKG. Because the licensee should be able 

to resolve all such alarms other than those of a statistical nature, calculation of the 

expected rate of irresolvable large abrupt loss false alarms needs only to consider false 

alarms of a statistical nature.

(2) After the phase-in period is over and all elements of the licensee’s alarm resolution 

commitments have been implemented, the NRC staff could determine that the alarm 

resolution performance is acceptable when (a) there have been no situations over the 

past year in which subsequent audits or investigations determined that a large abrupt 

loss alarm was innocently caused but not resolved within the licensee’s time 

commitments and (b) there are no unresolved large abrupt loss alarms remaining after 

the bimonthly inventories and annual audit have been completed.

5.3 Response Time

The MC&A plan should indicate response times that will be allotted to resolve each alarm type.

If alarms involving certain material types or alarms from certain processes need appreciably 

longer response times than those estimated in the acceptance criteria section below, the plan 

should justify the indicated times.

Acceptance Criteria:

• The alarm resolution time commitments ensure a reasonably prompt alarm response. The 

check of the loss indicator data for clerical mistakes and data errors should normally be 

completed within 24 hours for any abrupt loss alarm. The maximum time for completion of 

the resolution procedure for alarms indicating a possible abrupt loss of items that were 

tamper-safed, encapsulated, or retained in a vault that provided protection equivalent to 

tamper-safing should normally not exceed 3 calendar days. The maximum time for 

completion of the resolution procedure for alarms indicating a possible abrupt loss of SSNM 

in any form or container that was not tamper-safed, encapsulated, or stored in a vault 

equivalent to tamper-safing should not normally exceed 3 working days. However, if longer 
NUREG-1280, Revision 2 40

time periods are needed for certain unit processes or types of necessary response activities, 

the licensee should explain and justify the proposed times in its submitted MC&A plan.

• When a tamper-safed or encapsulated item has been compromised, the licensee should 

undertake a remeasurement immediately. The maximum time after the alarm for completing 

a remeasurement to confirm the contents should normally not exceed 2 working days. The 

licensee should explain and justify any proposed extension of that time. An example of 

when additional time might be necessary would be if isotopic measurements were to be

performed offsite.

• When a vault or CAA providing protection equivalent to tamper-safing has been entered 

without authorization, when the prescribed vault protection has been compromised, or when 

other indications of loss of control are discovered, the entire vault contents must be 

accounted for within 3 calendar days by a piece count and attribute test of all items not 

tamper-safed or encapsulated, such as by weighing or NDA. The licensee should initiate 

remeasurement of all items in the vault or CAA not tamper-safed or encapsulated within 

1 working day. If a longer period is proposed, the licensee should provide justification.

5.4 Item Discrepancies

The MC&A plan should describe actions that the licensee will take in response to the following 

item discrepancies:

• An item has apparently been destroyed without being recorded.

• The integrity of a tamper-safed or encapsulated item has been compromised.

• Unauthorized entry or other violation of control of a vault or a permanently CAA has 

occurred.

• A statistically significant difference between the measured input and output value of an

nontamper-safed item placed in a vault or CAA storage has been detected, and such 

difference exceeds 25 grams SSNM.

The actions in response to these discrepancies should include decision rules which will be the 

basis of acceptable resolution.

Acceptance Criteria:

• An item loss assessment procedure has been included that details a logical sequence of 

actions to resolve an apparent loss. A typical assessment sequence (not necessarily in the 

order listed) might be the following:

− Determine that the records are apparently correct by tracing the item identification and 

location information to its source data in inventory and production records.

− Search other production and storage areas to determine whether the item was 

transferred without supporting documentation.
41 NUREG-1280, Revision 2

− Identify all persons involved in the creation and movement of the item or items and 

question them for possible ways in which the item might have been misplaced or record 

errors made.

− Extend the search to other locations, particularly those suggested by the persons 

involved.

− Check for possible errors in the item records by evaluating the bulk material balances in 

the adjacent processing units.

− Reinventory all items of that type in storage locations routinely used for such items.

− Extend the inventory search to items of similar size and appearance.

• A description of the licensee’s proposed course of action in response to a broken TID should 

include the following:

− Place the item under surveillance immediately or in secured storage and remeasure it as 

soon as practicable (time limits specified) to determine whether SSNM is missing.

− Perform blending, mixing, or splitting operations, if appropriate, to ensure that any 

samples taken for remeasurement are representative.

− Compare (test) the difference between the original and confirmation measurement for 

statistical significance with a probability of no more than 5 percent of concluding that no 

SSNM is missing when in fact a loss has occurred. The quality of the remeasurement 

should be at least equivalent to the original measurement.

• If the cause of the alarm is claimed to be the destruction of an item, such as by processing it 

to another form, without the act having been recorded, confirmatory evidence should be 

developed to support the conclusion. The plan should describe the types of confirmatory 

evidence that are expected to be applicable. The evidence will be acceptable if it is 

relevant, concrete, independent, and objective. Examples of such evidence include the 

following:

− The measured density of a suspect solution is consistent with the predicted density,

assuming the contents of the missing container had been added to the process.

− The actual yield from a suspect unit process is consistent with the predicted yield from 

that process if it contained the contents of the missing item.

− Two individuals can attest to the fact that the container was added to the process.

• If an item is discovered as not being in its recorded location, such an event should be 

designated as an item discrepancy (with the time of such discovery being documented). If 

an item discrepancy is not resolved within 8 hours for Category IA items and within 24 hours 

for Category IB items, an alarm is declared. The licensee normally declares such an item as 

missing if not found or accounted for within 24 hours for Category IA items and 3 working 

days for all other items (relative to the time at which the item discrepancy was discovered).

A search for a misplaced item that was not tamper-safed or encapsulated may not be 

terminated without NRC permission until the item is located or evidence of its destruction is 
NUREG-1280, Revision 2 42

obtained. A claim that an item was destroyed without recording the fact may be accepted if 

independent confirmatory evidence of destruction is obtained. Searches for declared 

missing items may not be interrupted by idle time, such as weekends and holidays.

• If an item is discovered as being compromised and more than 25 grams of SSNM are

missing from the item, an MC&A alarm should be immediately declared.

• If the integrity of an item has been compromised (i.e., the container seal or the 

encapsulation has been altered or broken), an appropriate response procedure is promptly 

initiated to determine whether any SSNM is missing.

• Compromised items are placed under surveillance or in secure storage and are remeasured 

within specified time periods. The quality of the remeasurement is at least equal to that of 

the original measurement.

• Whenever an item monitoring test results in an MC&A alarm, a 5-FKG (or greater) loss 

should be assumed until shown otherwise either by additional (i.e., extra) item monitoring 

tests or by a physical inventory. If, when verifying n randomly selected items for an item 

test, one or more defects are encountered and the quantity of missing SSNM associated 

with the compromised or missing items is substantially less than 5 FKG, an immediate 

additional group of randomly selected items from the same stratum should be tested. In this 

additional test, the sample size should be twice as large (i.e., equal to 2n) and should not 

include any of the defective items from the initial test. If no alarm results upon performing 

the additional 2n test, strong evidence will have been obtained that a 5-FKG loss from the 

stratum in question did not occur. Depending on the circumstances, additional item tests on 

other strata may be necessary to resolve an item alarm. If the quantity of missing SSNM 

associated with the initial alarm is 4.000 FKG or more (i.e., not substantially less than 

5 FKG), the licensee should initiate a physical inventory of all items on hand. 

5.5 Alarm Reporting

As required by 10 CFR 74.57(c), a licensee must notify the NRC Operations Center of any 

MC&A alarm that remains unresolved beyond the time period specified for its resolution. 

Notification is to occur within 24 hours following the deadline for resolution or by the next 

working day when a weekend or holidays intervene. For alarm estimates that exceed 5 FKG, 

the notification that an MC&A alarm resolution procedure has been initiated is to occur within 

24 hours of the alarm occurrence.

The intent of these requirements is that the NRC be made aware of potential SSNM losses in a 

timely manner so that appropriate actions can be initiated.

The MC&A plan should indicate how the responsibility for reporting unresolved alarms will be 

assigned in the organization.

The plan should also discuss the types of information that will be provided to the NRC and the 

schedule for updating the status of the unresolved alarms to the NRC.
43 NUREG-1280, Revision 2

Acceptance Criteria:

• The appropriate NRC office will be provided with current, technically defensible information 

on the status of alarm resolution activities based on a mutually agreed upon schedule.

• The responsibility for reporting unresolved alarms is assigned at a sufficiently high level of 

responsibility within the licensee’s organization to ensure that decisions on the need for 

reporting will be timely and unquestioned.

• With regard to recurring losses, a significant loss trend is reported to the NRC within 1 week 

of its discovery, and the progress of the resulting investigation is reported monthly.

• The information to be reported includes the magnitude of the discrepancy indicated by the 

alarm, the investigation procedure, the status of the investigation, the status of the facility, 

the planned remedial measures, and the status of the physical security system during the 

period.

• The remedial measures include assignment of responsibility for the investigation to a 

technically competent individual, rechecking the response of the measurement system with 

certified standards, outlining a schedule of recalibrations of the key measurement systems if 

appropriate, in situ or cleanout measurements of holdup, and statistical evaluation of the 

material accounting data.

5.6 Alleged Thefts

The regulations in 10 CFR 74.57(e) require that a licensee establish and maintain ability to 

respond rapidly to alleged thefts.

Alleged thefts are alarms that originate external to the MC&A system. Among these are any 

statements that diversion of SSNM has occurred communicated directly or indirectly, for 

example, to facility staff, the NRC, the Federal Bureau of Investigation, or the police. The 

statements may or may not include details such as the plant area from which SSNM was 

allegedly taken, which items were taken, a description of the containers or material allegedly 

taken, or other information in support of the allegation. This covers threats allegedly from within 

as well as from outside the facility. An external alarm may include other indications, such as an 

external assault that penetrated an MAA or the discovery that an MAA door had been opened 

from the inside.

The intent of this requirement is to have an established capability to respond rapidly to alarms 

occurring external to the MC&A system. The response capability should provide the information 

necessary to rapidly assess the validity of an alleged theft.

The MC&A plan should describe the item control system that will be maintained to readily 

determine the identity, quantity, and location of SSNM in item form. The description should 

include the forms, records, and document flowpaths. For cases in which records are not 

centralized, the plan should describe the means of record verification by MC&A personnel and 

the responsibility for maintenance and disposition.
NUREG-1280, Revision 2 44

The plan should also describe the emergency physical inventory procedure, including an 

indication of the status that each unit operation should be in to be inventoried and the status of 

each unit operation during its inventory.

The annex to the MC&A should provide estimates of the times needed to perform and reconcile 

the inventory and to determine the associated projected variance.

The plan should describe the protective measures that the licensee will implement to prevent 

loss, misplacement, or accidental destruction of inventory and item location records. 

Acceptance Criteria:

• From the description of the SSNM item record system, it is evident that the records of the 

identity and location of every item can be updated with sufficient speed to support the 

commitments that any randomly selected item within a vault can be located within 8 hours, 

and any item outside a vault can be located within 24 hours. The capability also exists to 

locate all items within a vault within 72 hours and all items outside a vault or permanently

CAA within 1 week.

• Provisions are included for maintaining the availability of forms, tags, trained personnel, 

inventory listing, and other items that may be needed to initiate a plantwide physical 

inventory within 24 hours. The emergency inventory capability is designed to help answer 

the following questions:

− Can it be determined conclusively that SSNM is or is not missing from the facility?

− What quantity is missing?

− What material type is it? For example, what is its isotopic composition, its chemical

form, and its physical size?

− Over what time period could it have been diverted?

− Which plant employees or other individuals might have had access to it during that time?

− Which plant employees may be able to provide information useful for its recovery?

• Appropriate safeguards are implemented to prevent loss, misplacement, or accidental 

destruction of the inventory and item location records.

• The data collecting, recording, and auditing procedures provide reasonable protection 

against errors in the records.

5.7 Commitments and Acceptance Criteria

In its MC&A plan, the licensee should provide definitive commitments that adhere to the 

regulatory requirements and meet acceptance criteria applicable to alarm resolution. A finding 

that the licensee’s MC&A plan for conducting alarm resolution activities is acceptable and in 

accordance with 10 CFR 74.57 will be based on, but not limited to, the acceptance criteria listed 

in Sections 5.1 through 5.6 above.
45 NUREG-1280, Revision 2

6. MANAGEMENT STRUCTURE AND PERSONNEL 

QUALIFICATION AND TRAINING

6.0 Regulatory Intent

The intent of the 10 CFR 74.59(b) and 10 CFR 74.59(c) management structure and personnel 

qualification and training requirements is to ensure that licensees implement a management 

structure that permits effective functioning of the MC&A program and to ensure that the plant 

management structure will not adversely affect MC&A program performance. Documentation, 

review, and approval of critical MC&A procedures, as well as the assignment of the key 

functions to specific positions, eliminate ambiguities about what is to be done by whom. The 

management structure is meant to separate key MC&A functions from each other, thereby

incorporating checks and balances that increase MC&A system reliability and make the theft or 

diversion of SNM/SSNM less likely. It is also meant to free MC&A management from conflicts 

of interest with other major functions such as production.

6.1 Corporate Organization

The MC&A plan should describe the corporate structure and identify all corporate organization 

positions that have responsibilities related to MC&A at the licensee’s site. The plan should also 

describe corporate-level functions, responsibilities, and authorities for MC&A program oversight 

and assessments. At least one corporate official should have responsibilities pertaining to the 

control and accounting of all SNM/SSNM possessed by the licensee.

6.2 Plant or Site Organization

The MC&A plan should describe the site’s management structure with an emphasis on MC&A.

The plan should describe the site management structure to the extent that it can be clearly 

shown that the MC&A organization is independent of potentially conflicting responsibilities. This 

description should also indicate how responsibilities are assigned for the following functions:

• overall MC&A program

• SNM/SSNM custodianship 

• receiving and shipping of SNM/SSNM

• analytical laboratories 

• bulk and NDA measurements 

• sampling operations

• measurement control system

• physical inventories 

• onsite SNM/SSNM handling operations
NUREG-1280, Revision 2 46

• process monitoring

• item monitoring

• MC&A alarm resolution

The plan should briefly describe each site-level position outside of the MC&A organization that 

has responsibilities relating to MC&A activities (e.g., sampling, mass measurements, analytical 

measurements, and measurement control). For each position, the plan should clearly describe 

the functions, responsibilities, and authorities.

6.3 Material Control and Accounting Organization

The MC&A plan should provide an organizational chart and position-by-position description of 

the entire MC&A organization. An individual should be designated as the overall manager of 

the MC&A program, and the MC&A plan should demonstrate the independence of action and 

objectivity of decisionmaking of the MC&A manager. The individual should be in a position to 

recommend and initiate timely action for the control and accounting of SNM/SSNM, including 

delaying production if necessary, and should not be enmeshed in a hierarchical framework that 

could inhibit or compromise independent action. Two options for meeting the goal of 

organizational independence are for the MC&A manager to (1) report directly to the plant or site 

manager or (2) report to an individual who reports directly to the plant or site manager and who 

has no production responsibilities.

6.3.1 Responsibilities and Authority

The plan should provide a description that clearly indicates the responsibilities and authority of 

each supervisor and manager for the various functions within the MC&A organization. The 

description should indicate how the activities of one functional unit or individual serve as a 

control over, or checks on, the activities of other units or individuals. The MC&A plan should 

explain how coordination is achieved and maintained between the MC&A organization and other 

plant organizational groups that perform MC&A-related activities. A definitive statement should 

be made specifying how the MC&A manager ensures appropriate review and approval for all 

written procedures pertaining to MC&A-related activities (and any future revisions thereto) that 

are issued both within and outside of the MC&A organization. In addition to the MC&A manager 

function, the plan should address the following functions at a minimum:

• nuclear material accounting

• measurement control system

• process monitoring

• item monitoring

• alarm resolution

• statistical applications
47 NUREG-1280, Revision 2

Whenever more than one key MC&A function is assigned to the same person, the MC&A plan 

should clearly describe the checks and balances that preclude the following:

• performance of accounting or record control functions by individuals who also generate 

source data

• assignment of sole authority to any individual to overcheck, evaluate, or audit 

information for which he or she is responsible

Examples of appropriate checks and balances include the following:

• review of measurement data and calculations by another individual

• maintenance of a duplicate copy of all source data and transfer forms under controls 

separate from the accounting function

• performance of independent audits

• separation of computer program maintenance from the program user function

The management structure provides for assignment of a responsibility for SNM/SSNM

undergoing processing and in storage to a single individual or group. Duties include but are not 

limited to the following:

• maintaining appropriate inventory control over SNM/SSNM in their assigned area

• authorizing and recording all movements of SNM/SSNM into and out of their assigned 

area

• maintaining appropriate local MC&A records or ensuring that other records, such as 

production records, contain necessary MC&A information

• participating in physical inventories as required

• assisting in internal or external alarm resolution activities as required

• ensuring that, when SNM/SSNM is processed in bulk form, only authorized persons 

have hands-on access to the material

• notifying proper authorities of irregularities in material and MC&A data handling

For some individuals in management or supervisory positions, modifications to procedures, 

such as restricted access without escort to certain areas, may be necessary to provide sufficient 

assurance that the system cannot be compromised.

6.3.2 Material Control and Accounting Procedures

The MC&A plan should describe critical MC&A procedures, which are those written procedures 

that, if not performed correctly, could result in a failure to achieve one or more of the 

performance objectives of 10 CFR 74.3 and 10 CFR 74.51(a) and the program capabilities of 
NUREG-1280, Revision 2 48

10 CFR 74.51(c). The MC&A plan should describe MC&A procedures developed to perform 

MC&A tasks, the features of these procedures that contribute to minimizing human errors in 

MC&A data, and the control methods the licensee uses to ensure that current procedures are in 

place and are being used appropriately. Configuration control is a method by which the current 

official copies of procedures are maintained and controlled. Procedures that may be used in 

configuration control include sign offs by a responsible person on the released version, 

numbering and dating versions, and periodic checks of the individual procedures under the 

control of the procedure custodian or holder to make sure that current copies are being used. 

Control methods may include maintenance of a list of procedures, periodic review by operators 

and during audits, use of sign-off cover sheets, and validation during training sessions in which

procedures are available for subsequent monitoring during NRC inspections. This set of critical

MC&A procedures should, at a minimum, adequately address the following topics, regardless of 

which facility organizational group is responsible for the particular topic:

• process monitoring

• item monitoring

• alarm resolution activities

• sampling and measurements

• measurement control system

• accountability record system

• physical inventories

• detecting the loss of a goal quantity

• determination of SEID, active inventory, and ID

• investigation and resolution of loss indicators

• providing information to aid in investigations

• MC&A recordkeeping

• independent assessment of the effectiveness of the MC&A program

• tamper-safing

• designation of MBAs, item control areas (ICAs), and custodial responsibilities.

6.3.3 Human Errors

The licensee should develop and implement MC&A procedures in a manner that ensures that 

the frequency and consequences of human errors will be minimized and to enhance the 

likelihood of detection when they do occur. This can be achieved by a system of checks and 

balances in MC&A information systems that involve generating, collecting, processing, 
49 NUREG-1280, Revision 2

computing, analyzing, summarizing, and reporting data. Specific procedures should be 

available to guide personnel in performing major or complex tasks associated with MC&A. 

These procedures should be sufficiently explicit and comprehensive to promote error-free 

performance by the least skilled or least experienced person that will be assigned to perform the 

tasks specified by the procedures. Procedures should be self-contained to avoid the need to 

refer to supporting documents and written with flexibility in the sequence of events whenever 

possible. Knowledgeable personnel should prepare and review procedures before they are 

implemented. Lengthy or complex procedures should be validated by means of field tests to 

ensure their clarity, comprehensiveness, and effectiveness. Procedure terminology should be 

consistent with equipment, as should forms and other information to be employed by personnel 

at the facility.

The format of MC&A procedures is arranged to help to reduce the rate of human error and to 

detect mistakes. The complexity, sentence length, and grammatical structure should be 

appropriate to the educational level of the least qualified user. Short sentences with concise 

and unambiguous language are used, and the level of detail in instructions is adequate to avoid 

errors of omission. No more than three simple task elements are included per step, with more 

complex actions separated into additional steps. By restricting the amount of information that 

personnel are required to remember while performing a procedure, a greater probability exists 

that the procedure will be performed correctly. Remembering precise, numerical information is 

not a task that humans perform well. Using checklists or preprinted forms are methods to limit 

the amount of memorization required while reducing dependence on often bulky procedures.

Procedures should be formatted to allow experienced personnel to concentrate on major 

headings or capsule descriptions, while more detail is provided in clearly demarcated fashion for 

less experienced personnel. Procedures may be formatted in “cookbook” fashion for ease of 

use when appropriate. All steps and tasks should be stated as actions, and the sequence of 

steps and tasks should be performed in the same sequence to accomplish the objective of the 

procedure. Attention-getting warning and precaution notices should be placed immediately 

preceding applicable steps and, where required, should also be summarized at the beginning of 

the procedure. All required supplies, tools, test equipment, documents, and protective 

measures should be listed at the beginning of the procedure. All applicable referenced 

documents should be listed in one section of the procedure, quality control and quality 

assurance points should be identified, and decisionmaking cues should be clearly stated. 

Subtasks and subtests should be set off with separate headings or by appropriate indentation. 

The sequence of steps is logical and accurate, and unnecessary memory recall should be

avoided. The need for personnel to perform calculations and conversions should also be

avoided whenever possible. However, if lengthy tests and calculations cannot be avoided, data 

collection tables and data reduction aids should be provided. Preprinted forms for recording 

data should be utilized when practical, and multiple copies of forms, if needed, should be

generated automatically in the data collection phase.

6.3.4 Job Performance Aids

MC&A procedures may include job performance aids (JPAs), where applicable, that help to 

reduce the frequency of human errors. JPAs for highly complex MC&A tasks assist novice 

users in their performance while not hindering the performance of experienced users. Attributes 

of such JPAs include, but are not limited to, the following:

• Terms and labels match common usage for equipment labels and legends.
NUREG-1280, Revision 2 50

• Quantities and dimensional units correspond to referenced displays, documents, and 

information.

• Uncommon and inconsistent abbreviations are avoided.

• The presentation of illustrations, graphs, and tables, if used, is consistent throughout the 

procedure.

• Checklists or data tables are provided for lengthy prerequisites, tests, and calculations.

• Illustrations are used in place of long descriptions, where possible; are placed so that 

they can be referenced easily from the text section; and are clearly labeled and easy to 

read.

• All tables and graphs are clearly labeled in quantitative terms.

Some examples of successfully used JPAs are illustrations and diagrams, graphs for 

interpolation, approximate times to complete specific jobs, clearly stated decisionmaking cues 

and clues to the correct decision given specific cues, and data reduction aids. JPAs are useful 

so long as they do not cause the procedure to become difficult to use because of too many aids, 

the wrong types of aids, or presentation in an inappropriate manner. A procedure written so that 

an experienced user can omit unnecessary aids meant for novice users is in itself a JPA and will 

encourage procedure usage.

6.4 Training and Qualification Requirements

This section of the MC&A plan should describe the training programs to be established and 

maintained to ensure qualified personnel and to provide for the continuing level of qualification 

with respect to personnel assigned to MC&A responsibilities.

6.4.1 Training Program

The training program should ensure that the individuals assigned key MC&A positions (i.e., 

those involving tasks for which mistakes could directly degrade the safeguards capabilities of 

the MC&A system) are trained to maintain a high level of safeguards awareness and are 

adequately prepared to perform their functions correctly with a minimum of errors. The program 

should be structured to define job requirements, establish minimum qualifications for 

candidates, train and qualify the candidates, and define requalification criteria. The description 

of the program should identify the training program structure, source of instructional material, 

and general training objectives.

The list of key positions or functions should include all those for which errors or faulty 

performance could directly degrade SNM/SSNM control and accounting. These include MC&A 

management positions and individual contributor positions having responsibility for key 

measurements, data analysis, preparation of accountability source documents, and collecting or 

recording of other data having a direct impact on loss detection, alarm response, and quality 

assurance functions.
51 NUREG-1280, Revision 2

The training program emphasizes the job purpose and scope; relationship to other positions, 

especially the MC&A positions; the role or significance with respect to MC&A; technical 

knowledge; understanding of duties, responsibilities, and procedures; and skill development.

The training plans provide for a reasonable balance of theory and practice or oral and written 

instruction versus demonstration and learning by doing, the use of on-the-job training for 

positions that are primarily operational or clerical, and individualized instruction based on 

performance goals whenever feasible.

The training program provides for training of personnel already experienced and functioning in 

MC&A positions when competency tests indicate that additional training is necessary. The 

criterion will be whether or not the individual can function at the level of proficiency called for in 

the qualification criteria.

6.4.2 Qualification Program

The qualification criteria for the key positions are consistent with the position descriptions and 

focus on minimum levels of education and experience, knowledge of the job content and its 

purposes, types and levels of skills or proficiencies, and understanding of the safeguards role 

and its importance. The criteria are defined in terms of measurable performance goals 

whenever possible.

Tests for positions requiring measurements, calculations, or recording of data and information 

will include demonstration of correct and accurate job performance. When operating 

procedures or manipulative skills are required, the tests will include hands-on demonstrations 

on competence.

The annex to the MC&A plan should provide an example of a typical training program for one 

typical position, a tabulation of the key MC&A positions, and an example of the complete 

qualification criteria for a key MC&A position.

6.5 Material Control and Accounting Program Description

The length of this section and its level of detail will depend on the information provided in the 

previous sections of this chapter. The licensee should describe the overall MC&A organization 

in a manner that explains how its MC&A program will effectively achieve the general 

performance objectives of 10 CFR 74.3 and the capabilities of 10 CFR 74.51(c).

The individual who has responsibility for each of the following MC&A-related functions should be 

specified by title:

• overall MC&A program management 

• measurements 

• measurement control and statistics

• accountability records
NUREG-1280, Revision 2 52

• process monitoring

• item monitoring

• alarm resolution

• physical inventories

• custodial responsibilities (e.g., SNM/SSNM storage and movement controls)

• investigation and resolution of indicators that suggest possible loss of SNM/SSNM

• receiving and shipping of SNM/SSNM

• analytical laboratories

• MC&A recordkeeping system and controls

The individual responsible for the overall MC&A program management should have no major 

non-MC&A-related responsibilities. Measurement responsibility may be divided on the basis of 

the type of measurements (e.g., analytical laboratory measurements, NDA measurements, bulk 

measurements, and sampling). 

The MC&A program description should define the policies, instructions, procedures, duties, 

responsibilities, and delegation of authority in sufficient detail to demonstrate the separation of 

duties or overchecks built into the MC&A program.

6.5.1 Automation of Material Control and Accounting

The MC&A plan should describe the methods and technologies used to automate MC&A 

functions and the features of these methods that contribute to minimizing human errors in 

MC&A data. MC&A activities associated with collecting and processing data, recordkeeping, 

and auditing should be automated where it is practical and advantageous to do so. MC&A data 

are directly collected, inputted, checked, manipulated, reported, and audited by computer when

it is practical and advantageous to reduce the consequences and frequency of human error as 

much as practical.

6.5.2 Human Error Quality Control

The MC&A plan should describe the quality control system that will be used to monitor the 

frequency and types of human errors. The plan should also describe the techniques that will be 

employed to minimize the frequency and consequences of human errors and enhance the 

likelihood that they will be detected when they do occur. The description should address use of

the following:

• Control methods to ensure that current procedures are in place and being used

• JPAs

• automated data processing
53 NUREG-1280, Revision 2

• personnel training and qualification

• preprinted forms

• multiple copy forms

• data verification

A quality control system should be in place to monitor the frequency of human errors and permit 

categorization of the types of errors encountered. Statistical quality control systems should be 

used to track the effectiveness of human error control measures and the frequency of human 

error in MC&A systems, as well as to alert management whenever the rate of human error is in 

an out-of-tolerance condition. Such a quality control system includes, but is not limited to, the 

following:

• The quality control system is capable of determining if and when an individual, 

procedure, or process makes more errors than is reasonably expected.

• The quality control system is capable of determining the following:

– the individuals who require retraining because of their frequency of committing 

errors

– the procedures and processes that should be revised to produce fewer human 

errors

• Double checklists are provided to allow periodic, random auditing of data collection by a 

supervisor or other independent person who checks the results of the first person’s work 

and signs off when the work is complete and accurate. The originator should check 

each data collection form to verify that the data are accurate.

• When MC&A data processing is automated, quality control systems are also automated, 

so that out-of-tolerance conditions, human errors, and other warnings can be detected 

promptly.

• A configuration management plan is established for vital MC&A equipment, computer 

software, and manuals.

• Configuration control measures are performed systematically and immediately reflect all 

changes as they are made.

• Procedures and technical manuals are stored, indexed, filed, and controlled in a manner 

that ensures easy retrieval and availability.

• Estimates of human error rates are based on a human reliability analysis of the data 

collection process to determine a reasonable rate of human error in MC&A data for the 

specific licensee.
NUREG-1280, Revision 2 54

• Reasonable estimates of human error rates include input regarding equipment design, 

plant policies and practices, and written procedures.

• Reasonable estimates of human error rates include input regarding situational and 

personnel factors that may produce errors.

• Any potential problems that can reasonably be resolved following a human reliability 

analysis are resolved and the estimates of a reasonable error rate recalculated.

6.6 Commitments and Acceptance Criteria

In its MC&A plan, the licensee should provide definitive commitments that adhere to the 

regulatory requirements and meet acceptance criteria applicable to management structure and 

training and qualification. A finding that the licensee’s MC&A plan describing management 

structure and training and qualification is acceptable and in accordance with 10 CFR 74.59(b) 

and 10 CFR 74.59(c) will be based on, but not limited to, the following acceptance criteria:

• The authorship, approval authorizations, and effective dates of MC&A policies and 

procedures will be documented and will involve appropriate management and technical 

staff.

• The responsibilities and authorities for each position assigned a function having a 

significant impact on SNM/SSNM control and accounting (including all positions 

authorized to control SNM/SSNM movement, generate source data, define or implement 

measurement control requirements, and conduct data analysis) are clearly defined in a 

written position description that details the responsibilities for that position.

• The qualifications and experience required for each position assigned SNM/SSNM

control and accounting functions will be sufficient to permit adequate performance of the 

duties required of that position.

• The descriptions in the MC&A plan of the management structure and assignment of 

duties and authorities show that those responsible for each MC&A function will have 

sufficient authority to perform the function in the intended manner.

• The MC&A organization is separate from the production organization and is also 

separate from organizations that generate source data, if practical; otherwise, 

independence of the functions is attained by suitable controls and overchecks.

• The responsibility for MC&A program management is designated to an individual at an 

organizational level sufficient to ensure independence of action and objectiveness of 

decisions. The overall management responsibility for the MC&A systems is at a level at 

least comparable to the organization having responsibility for production or storage of 

SNM/SSNM, or a direct line of communication is provided to the management level 

which has authority to implement measures essential to effective MC&A.
55 NUREG-1280, Revision 2

• No two key MC&A functions are assigned to the same person unless sufficient checks 

and balances are provided. The following limitations are a consequence of this criterion:

− Individuals who generate source data, such as performing measurements, or 

who perform shipping and receiving activities do not perform any accounting or 

record control functions unless suitable overchecks are provided to prevent 

falsification of both source data and accounting records.

− No individual has the sole authority to overcheck, evaluate performance, or audit 

information for which he or she is responsible.

• No individual may have responsibility and control of both MC&A and physical protection 

functions unless independent cross-checks are in place to preclude defeat of the overall 

safeguards system. At a minimum, the cross-check must include countersigning by one 

other person of any SNM/SSNM transfer within an MAA and countersigning by two 

individuals for SNM/SSNM transfers out of an MAA.

• All current critical MC&A procedures are made easily accessible to all affected 

individuals and, for each procedure, the following are maintained: (1) revision number, 

(2) date issued, (3) identity of who prepared the procedure, and (4) identity of who 

approved the procedure (as indicated by signature and date signed).

• Sufficient checks and balances are incorporated to detect falsification of data and 

reports that could conceal theft or diversion of SNM/SSNM by a single individual, 

including an employee in any position, and collusion between two individuals, one or 

both of which have access to SNM/SSNM.

• A training and qualification program for key MC&A positions and a method of 

demonstrating continued competency of personnel have been implemented and will be 

maintained. The program is periodically updated to reflect changes in job requirements 

as outlined below:

• The description of the key job functions, the design of the training and 

qualification program, and the method of confirming qualifications of personnel 

are subject to the formal approval of the MC&A manager.

• The continuing qualification of key personnel will be verified on an ongoing basis 

or at least every 2 years. The individuals designated for key positions do not 

assume the positions until they have demonstrated their competence through 

tests that will determine whether or not the individual satisfies the preestablished 

qualification criteria for the positions.

• The facility organization and the MC&A policies and procedures are documented.

• All critical MC&A procedures, and any revisions thereto, are reviewed and 

approved before their implementation.

• Management policies are established, documented, and maintained to ensure 

that all critical MC&A procedures are adhered to, including measurement 

procedures used for accountability purposes.

57 NUREG-1280, Revision 2

7. MEASUREMENTS

7.0 Regulatory Intent

The intent of the 10 CFR 74.59(d) measurement capability requirements is that licensees 

establish, utilize, and maintain a system of measurements to ensure that all quantities of 

SNM/SSNM (both element and fissile isotope) in their accounting records are based on reliable 

measurements.

The measurement systems used must be sufficient to do the following:

• Substantiate the element and fissile isotope content of all SNM/SSNM received, 

produced, and transferred between areas of custodial responsibility; on inventory; or 

shipped, discarded, or otherwise removed from inventory.

• Provide the necessary data for the performance of the material control tests required by 

10 CFR 74.53(b)(2).

• Permit an estimation of the standard deviations associated with each measured quantity.

The measurement uncertainty associated with the values entered into the accounting records 

should be sufficiently small to ensure the limit specified in 10 CFR 74.59(e)(5), for the total 

MC&A measurement uncertainty (associated with a material balance), is not exceeded. Except 

for sealed sources and samples (that have been determined by other means to contain less 

than 10 grams of U-235, U-233, or plutonium each), all SNM/SSNM receipts are to be 

measured for the purpose of performing shipper-receiver evaluations. In the absence of any 

significant shipper-receiver difference, a licensee may book either its measured values or the 

shipper’s measured values. When recording shipper’s values (for SNM/SSNM receipts), the 

measurement uncertainty associated with the shipper’s values should be known and used in the 

determination of the SEID. It is also intended that a licensee’s measurement program provide 

bias estimates to be used in correcting ID values and shipper-receiver differences for significant 

measurement biases. Chapter 8 of this document discusses the estimation of measurement 

bias. The licensee should measure heterogeneous scrap that cannot be accurately measured 

in its as-received form after dissolution within 18 months of receipt.

7.1 Measurement Points

The MC&A plan should identify and describe each measurement that is used for accounting 

purposes. Measurements (1) establish the quantities in each custodial area, MBA, or ICA and 

in the facility as a whole and (2) contribute to the desired capability to localize losses and to 

generate and assess alarms. Measurement points and sampling stations should be selected to 

provide quantitative information about material flows and inventories that will permit detection 

and localization of any loss or diversion or to confirm that no theft or diversion has occurred. 

Typically, three functional types of MBAs and ICAs are present: (1) processing, (2) storage, and 

(3) receiving and shipping. The identification and definition of measurement points for 

processing MBAs are necessary because of the physical or chemical changes of the nuclear 

materials that occur in these MBAs. The storage and the receiving and shipping areas are 

typically ICAs. Typical processing MBAs include (1) processing areas, (2) decontamination and 

recovery areas, (3) laboratory areas, and (4) feed and product sampling and transfer areas. 
NUREG-1280, Revision 2 58

The following measurement points are usually included, although the licensee is not limited to 

them:

• facility receipts

• transfers between areas of custodial responsibility

• points at which SNM/SSNM product or intermediate products are produced

• unit process boundaries

• facility shipments, including product, scrap, and waste

• effluent discharge points

• significant sidestreams

The MC&A plan should characterize materials and measurements for each measurement point. 

One suitable means of presentation would be a coded chart showing the types of materials and 

the components of measurement involved at each measurement point (i.e., weight, volume, 

sampling, analytical assay, or NDA). The use of factors is acceptable whenever the uncertainty 

associated with the factor is smaller than the random error of an applicable process material (or 

item) measurement. Otherwise, the use of factors should be limited to those situations for 

which timely measurements are impractical. The plan should include a commitment to the 

effect that factors will be based on measurements, monitored, and updated when appropriate 

statistical tests indicate the need for updating. In the annex to the MC&A plan, the licensee 

should justify the use of factors in lieu of measurements.

The acceptability of applying nominal (or historic) SNM/SSNM factors to measurement of mass, 

volume, or density for material control tests will depend upon the following considerations:

• availability of substitute materials

• predictability of material composition

• material accessibility.

These considerations influence whether a test as simple as a weight comparison will suffice as 

a means of loss detection or if a measurement for element and perhaps isotope is necessary.

7.2 Measurement Systems

The MC&A plan should describe in detail each measurement system used for nuclear material 

accounting purposes. The principal elements and operations involved in the measurement 

systems for MC&A encompass mass (or weight) or volume determination, sampling, chemical 

analyses for element and isotope, and NDA. Each measurement system should also be defined 

or identified by its unique set of the following parameters: (1) measurement device or 

equipment used, (2) standards used for calibration, and (3) standards used for control. 

Additionally, for analytical laboratory measurements, the following also should be identified: 

(1) sampling technique and equipment used, (2) sample aliquoting technique, and (3) sample 
59 NUREG-1280, Revision 2

pretreatment methodology. Chapter 6 of this document describes the elements of the 

measurement control system (e.g., standards traceable to a national system) used for validating 

and determining control limits and precision and accuracy levels for each measurement system 

used for accountability.

The MC&A plan should describe each measurement system associated with bulk, analytical, 

and NDA measurements and should identify, as applicable, any other measurement systems 

used for accounting purposes that do not fall within these categories. These descriptions 

should provide sufficient information to demonstrate how the systems are implemented to 

ensure the capability to meet the precision and accuracy limits. The following sections provide 

examples of the types of information necessary for selected measurement systems.

7.2.1 Bulk Measurement Systems

For each weighing system, the applicant or licensee should specify the type of weighing device, 

the type of containers weighed, material within the containers being weighed, capacity of the 

weighing device, range to be used, sensitivity of the device, and the calibration frequency. The 

description should include the capacity and the sensitivity of the scale (e.g., capacity not to 

exceed X kilograms, and sensitivity to be at least as good as Y grams).

For each volume measurement system, the MC&A plan should identify the vessel (e.g., tank, 

column), capacity of the vessel to which the measurement applies, the material being 

measured, the volume measuring device and instrumentation, the sensitivity of each device and 

system, the range of operation and calibration, and the calibration frequency.

7.2.2 Analytical Measurement Systems

For each analytical measurement system, the MC&A plan should specify the following:

• type of material or chemical compound being sampled and measured (e.g., plutonium 

dioxide (PuO2), plutonium metal or alloy, mixed oxide (PuO2-UO2), uranium hexafluoride 

(UF6), uranium alloy, uranium dioxide (UO2), uranyl nitrate solution (UNH))

• sampling techniques

• sample handling (i.e., preanalysis sample storage and treatment)

• analytical method used

• characteristics measured (e.g., grams of uranium or plutonium per gram sample or 

U-235 or U-233 isotopic concentration)

• measurement interferences

• expected measurement uncertainty

• types of calibration standards and calibration frequency
NUREG-1280, Revision 2 60

7.2.3 Nondestructive Assay Measurement Systems

For each NDA measurement system, the MC&A plan should identify the following:

• the NDA equipment package (i.e., type and size of detector and type of associated 

electronics and computer interface, as appropriate)

• the type of container measured

• SNM/SSNM material type within container

• sampling techniques, if applicable

• attribute measured

• measurement configuration (including source to detector distance)

• calculation method

• expected measurement uncertainties

7.2.4 Other Measurement Systems

If applicable, the MC&A plan should also identify any other measurement systems used for 

accounting purposes that do not fall within the three categories discussed in Sections 7.2.1, 

7.2.2, and 7.2.3 of this document. 

7.3 Measurement Uncertainties

The MC&A plan should provide the expected measurement uncertainties of the described 

measurement systems. The plan should also state the variance components for calibration, 

sampling, random, and systematic error for each measurement system. The units in which the 

errors are expressed should be clearly identified.

7.4 Measurement Procedures

The licensee or applicant should demonstrate that measurement procedures (i.e., methods) are 

established, approved, and maintained. This can be accomplished by (1) making a definitive 

statement that an approved measurement procedure (i.e., methods) manual, or set of approved 

manuals, is established and maintained, (2) stating which organizational units are responsible 

for the preparation, revision, and approval of measurement procedures, and (3) defining the 

standards for periodic review of the procedures.

The licensee should make a clear statement defining how the facility will ensure that a 

measurement procedure cannot be used for accountability purposes without documented 

approval. Each procedure should be approved by the overall MC&A manager and by the 

manager of the organizational unit responsible for performing the measurement. The 

measurement control program manager should also approve measurement procedures.
61 NUREG-1280, Revision 2

The MC&A plan should provide a definitive statement that all SNM/SSNM quantities in the 

material accounting records are based on measured values and that measurement systems are 

maintained for the measurement of SNM/SSNM associated with the following:

• additions to inventory (e.g., receipts)

• withdrawals from inventory (e.g., shipments and measured discards)

• material on ending inventory

For receipt of material, the licensee may use the shipper’s measured values rather than its own 

measurements, provided that (1) a shipper-receiver comparison, based on attributes or 

confirmatory measurements, shows no significant shipper-receiver difference (as defined by 

10 CFR 74.59(h)(1)(iii)), (2) in the case of a significant difference between shipper and receiver, 

no significant difference exists between the shipper’s value and the umpire value used to 

resolve the difference, or (3) the material in question is exempted from shipper-receiver 

comparison requirements (e.g., sealed sources and samples). However, when booking 

shipper’s values, the licensee should use the shipper’s measurement uncertainty when 

determining the SEID.

7.5 Scrap Control

Heterogeneous scrap that cannot be accurately measured in its received form need not be 

measured until after dissolution within 18 calendar months of receipt. The after-dissolution 

measurement should include measurement of both the resulting solution and any undissolved 

residues before any commingling with other scrap solutions or residues. In the meantime, the 

licensee should use the shipper’s value or an appropriate factor-based value for inventory 

purposes.

7.6 Commitments and Acceptance Criteria

In its MC&A plan, the licensee should provide definitive commitments that adhere to the 

regulatory requirements and meet acceptance criteria applicable to measurements. A finding 

that the licensee’s MC&A plan describing measurement systems is acceptable and in 

accordance with 10 CFR 74.59(d) will be based on, but not limited to, the following acceptance 

criteria:

• A system is established, maintained, and utilized for the measurement of all SNM/SSNM

received, produced, and transferred between internal control areas; on inventory; or 

shipped, discarded, or otherwise removed from inventory, except for the following:

− sealed sources that have been determined by other means to contain less than 

10 grams of U-235, U-233, or plutonium each

− samples received, transferred between internal control areas, or on inventory that 

have been determined by other means to contain less than 10 grams of U-235, 

U-233, or plutonium each

− receipt of sealed sources, of any quantity, previously manufactured and shipped 

by the licensee and which are returned to the licensee, provided the unique 
NUREG-1280, Revision 2 62

identity and encapsulation integrity have not been compromised and the booked 

receipt quantity equals the previously shipped quantity for the involved sealed 

sources

− heterogeneous scrap that cannot be accurately measured in its as-received form, 

provided such scrap is measured after dissolution within 18 months of receipt (to 

include measurement of both the resulting solution and any undissolved residues 

before any commingling with other scrap solutions or residues)

• A system is maintained and followed for the development and use of written procedures,

which includes documented review and approval of such procedures and any revisions 

thereof before use. Procedures will address the following:

− preparing or acquiring, maintaining, storing, and using reference standards and 

standard reference materials

− calibrating measurement systems, performing bulk mass and volume 

measurements, conducting NDA measurements, obtaining samples, and 

performing laboratory analyses for element concentration and fissile isotope 

abundance

− recording, reviewing, and reporting measurement data and measurement results

• A basic description or summary of each key measurement system which is utilized to 

generate SNM/SSNM quantities for accountability purposes is provided. A 

measurement system is defined as any instrument or device, or combination of devices, 

used to derive (1) an element concentration, (2) an isotope quantity, (3) a U-235 

enrichment or isotopic distribution, (4) a bulk material mass (weight), or (5) a bulk 

material volume and which can be characterized by its random and systematic error 

components.

• The set of key measurement systems, based on recent (or anticipated) measurement 

control data and modes of process operations, is expected to account for at least 

90 percent of the total measurement uncertainty contribution to the SEID.

• The recalibration frequency for each measurement system is compatible with its 

expected stability. Recalibrations for all measurement systems should be performed at 

frequencies compatible with widely established, or licensee-demonstrated, stability for 

each particular system.

• All calibrations are made with the use of primary standards or primary reference 

materials (certified and issued by the National Institute of Standards and Technology,

the New Brunswick Laboratory, or an equivalent organization) or with reference 

standards traceable to primary standards. The standards used for calibrations need not 

be representative of the unknowns to be measured by the system unless it is to be 

regarded as a bias-free system that is calibrated during each time of use, in which case 

the calibrations standards should be representative.

• When determining an SNM/SSNM quantity by weighing, sampling, and analyses, the net 

weight of material in each item within a uniform material batch (or lot), such as blended 
63 NUREG-1280, Revision 2

PuO2 or UO2 powder, plutonium metal, or sintered UO2 pellets, should be determined by

direct mass measurement. However, the element or isotope concentrations, or both, for 

the batch need not be determined for each container, but instead may be derived by 

sampling procedures, including the following:

– analysis of composite samples or measurements of representative items, 

objects, or samples selected by statistical sampling

– use of concentration or enrichment factors, or both, determined from historical 

averages, controlled input specification values, or empirical relationships when

such values or relationships are periodically tested, their uncertainties or bounds 

have been determined to be within 2 percent of the factor value, and diversions 

with material substitution are improbable.

• A program of measurement procedures and methods is maintained for all SNM/SSNM

receipts, removals, and inventory items, and all quantities of SNM/SSNM in the material 

accounting records are based on measured values.

• Measurement systems that are the key contributors to the total measurement standard 

error are identified. The list will be reviewed annually and updated as necessary. The

systems on this list are considered to be key measurement systems, and their standard 

deviations are monitored and controlled by the measurement control program.

• Measurement systems are maintained and utilized to substantiate the element and 

isotope content of all SNM/SSNM received, produced, or transferred between areas of 

custodial responsibility; on inventory; or shipped, discarded, or otherwise removed from 

inventory.

• SNM/SSNM quantities transferred into and out of each unit process are based on 

measurements for mass, volume, element, and isotope, as necessary, to accommodate 

material loss detection tests.

• Measurement methods are appropriate for the matrix and SNM/SSNM characteristics of 

the material measured.

• Factors employed in process models are based on measurements and are updated at 

least annually.

65 NUREG-1280, Revision 2

8. MEASUREMENT CONTROL SYSTEM

8.0 Regulatory Intent

The intent of the 10 CFR 74.59(e) measurement control requirements is that measurement 

systems (described in Chapter 7 of this document) used to establish SNM/SSNM accountability 

quantities be controlled by a formal measurement control system that results in a level of 

effectiveness sufficient to satisfy the capabilities required for detection, response, and 

accounting. The quality of SNM/SSNM measurements should be continually controlled such 

that the SEID is maintained within the limits specified in 10 CFR 74.59(e)(5), and measurement 

error contribution to the standard deviations associated with the material control tests required 

by 10 CFR 74.53(b) is minimized. It is also intended that the measurement control system

provide bias estimates to be used for adjusting ID results and correcting shipper-receiver 

measurements for significant measurement biases.

8.1 Organization and Management

The MC&A plan should describe the organization and management of the measurement control 

system in sufficient detail to demonstrate how the measurement quality assurance function is 

assigned and how independence from the analytical laboratory and other units performing either 

sample taking or measurements is maintained. The measurement control system manager 

should be at a management level that is sufficiently high to ensure objectivity and independence 

of action. Thus, the measurement control system manager could either report directly to the 

overall MC&A manager or, if in a different organizational unit, be on the same level as the 

MC&A manager.

The licensee’s measurement control system should be properly managed to ensure adequate 

calibration frequencies, sufficient control of biases, and sufficient measurement precision to 

achieve the capabilities required by 10 CFR 74.59(e).

8.1.1 Functional Relationships

The MC&A plan should clearly define the relationship and coordination between the 

measurement control system manager, the analytical laboratory, and other measurement 

performing groups. The plan should provide adequate assurance that the measurement control 

system manager has the authority to enforce all applicable measurement control requirements.

8.1.2 Procedures

The measurement control system procedures should be established and maintained in a 

manual that is kept current and readily available. This manual should contain all of the currently 

applicable written procedures pertaining to measurement control and measurement quality 

assurance. The MC&A plan should specify the responsibility for the preparation, revision, and 

approval of manual procedures. Individual measurement control procedures should have 

documented approval by the measurement control system manager. The procedures should 

address the following:

• calibration frequencies and methods
NUREG-1280, Revision 2 66

• standards used for calibration (i.e., description and storage controls)

• standards used for control (i.e., method of obtaining or preparation and traceability)

• control standard measurements

• replicate sampling and replicate measurements

• verification of process control instrumentation through comparison with other process 

instruments

• control limits and control responses

• generation and collection of control data

• recordkeeping controls and requirements

8.1.3 Contractor Program Audits and Reviews

If an outside contractor or offsite laboratory provides measurement services, the MC&A plan 

should describe the review program used to monitor the offsite measurements in accordance 

with 10 CFR 74.59(h)(4). Such reviews are to confirm that the contractor or offsite laboratory 

has an acceptable measurement control program to ensure that the use of the contractor’s 

measurements will not compromise the licensee’s ability to meet any measurement or 

measurement control requirement contained in its MC&A plan. The licensee should conduct an 

initial review of the contractor’s measurement control program before using measurements 

performed by the contractor or offsite laboratory.

All contractor or offsite laboratory assessment findings and recommendations should be 

documented and submitted to both the measurement control system manager and the overall 

MC&A manager within 30 days of completion of the review. The two managers should agree on 

corrective actions that should be taken, based on their evaluation of the report, and should 

transmit these findings to the contractor or offsite laboratory in writing. The licensee should not 

use measurements performed by such contractors or offsite laboratories until they have verified 

that the corrective actions have been instituted.

The persons who conduct a contractor review need not be employed by the licensee; but they 

should not be employed by, or in any way be associated with, the contractor or offsite laboratory 

so that the independence of the conclusions may be maintained.

8.2 Calibrations

The MC&A plan should summarize the licensee’s calibration program and confirm that the 

licensee has written procedures covering the following topics:

• calibration frequency for each measurement device or system

• identification of the standards used for calibration of each measurement device or 

system
67 NUREG-1280, Revision 2

• protection and control of standards used to calibrate measurement systems to maintain 

the validity of their certified or assigned values

• the range of calibration for each measurement device or system and the minimum 

number of calibration runs (observations) needed to establish a calibration

Unlike control standards, standards used for calibrating measurement systems need not be 

representative of the process material or items to be measured by the calibrated device or 

system. If practical, the standard used during the calibration process should be subjected to all 

of the steps involved in the measurement process to which the process unknowns are subjected 

(e.g., sample pretreatment), but this need not always be the case. It is the primary 

measurement device, not necessarily the entire measurement system, that needs to be 

calibrated, especially when the primary measurement device is common to two or more 

measurement systems. For example, the Davies & Gray titrimetric method is often used to 

analyze samples for uranium concentration of two or more different material types (e.g., UF6, 

UO2, UNH solutions). In this case, more than one measurement system is involved because 

different sampling and sample pretreatment methods and different control standards are used. 

The potassium dichromate titrant, however, is common to the systems; thus, the titrant is what 

is calibrated (or standardized) with a primary reference material, such as certified potassium 

dichromate (K2Cr2O7), certified urano-uranic oxide (U3O8), or certified uranium metal.

In the case of nonconsumable standards used to calibrate measurement systems (e.g., weight 

standards), the MC&A plan should specify the frequency of recertification of assigned values. 

The recertification frequency should depend on how often the standards are handled, the 

standard’s stability, and the adequacy of the controls used to maintain the integrity of the 

standards. Biennial recertification of such standards is usually acceptable. 

The MC&A plan should contain a definitive statement that no SNM/SSNM accountability value is 

based on a measurement that falls outside the range of calibration. The MC&A plan also should 

identify those measurement systems that are point calibrated. A point-calibrated measurement 

system is one in which the following conditions are true:

• The entire measurement system is calibrated with a standard or set of standards that is 

representative of the process unknowns that are measured by the system. That is, the 

representative calibration standards undergo all of the measurement steps, and in the 

same manner, that the unknowns undergo.

• One or more calibration standards are processed and measured along with each 

unknown or set of unknowns measured. That is, both the standards and the unknowns 

are measured during the same general time interval, with the same individual measuring 

both the standards and the unknowns.

• The measurement values assigned to the process unknowns are derived from the 

measurement response observed for the standards that were measured along with the 

unknowns.

• The measurement response for each unknown should fall within plus or minus 

10 percent of the response for a standard measured at the same time as the unknown 

or, as in the case of a low concentration unknown, the difference between the unknown’s 
NUREG-1280, Revision 2 68

response and the standard’s response should be less than four times the standard 

deviation associated with the standard’s response.

Calibration procedures should be adequate to ensure that the measurement systems will 

generate reliable results. Considerations in this regard include the following:

• The number of runs to establish the initial calibration is sufficient to establish a 

reproducible calibration.

• The calibration range spans the anticipated range of process values, and standards for 

calibration are adequately spread over the range.

• For point calibrations utilizing a single calibration standard, the unknowns should be 

within plus or minus 10 percent of the assigned value of the involved standard.

Control standard measurements should be spread out across the material balance period with 

the expressed objectives of monitoring calibrations for trends or sudden shifts and providing the 

necessary data for bias estimates.

Recalibrations are performed when a need is identified. Recalibrations would be deemed 

necessary when the following circumstances exist:

• A trend, shift, or out-of-control condition at the 0.001 level is detected.

• A bias estimate is statistically significant at the 95-percent confidence level.

• A change in process materials occurs that extends or shifts the needed range of 

calibration.

• A change or modification is made to a measurement system that has the potential to 

affect measurement results.

8.3 Control Standards

For those measurement systems that are not point calibrated, the licensee should establish and 

follow a defined method for the periodic measurement of control standards. Control standard 

measurements serve the dual purpose of (1) monitoring the stability of a previously determined 

calibration factor and (2) estimating the average system bias over a period of time (e.g., an 

inventory period). The MC&A plan should specify the minimum total number of control standard 

measurements during the time period, as well as the typical frequency, for each measurement 

system. Generally speaking, for each key measurement system, a minimum of two control 

standard measurements should be made during each week that the system is in use. For those 

key systems that are used less than 8 weeks during a given material balance period, more than 

two control standard measurements per week of system use may be necessary to provide a 

measurement system performance that is controlled such that the SEID will not exceed 

0.1 percent of the active inventory.

The measurement control system should produce data that are representative of actual 

operating conditions and all errors that impact ID. The larger uncertainty estimates that 
69 NUREG-1280, Revision 2

collectively contribute 90 percent or more to the standard error of the ID estimator will be based 

on a minimum of 15 standard or replicate process material measurements, as appropriate.

The set of key measurement systems should include any system utilized to measure an 

SNM/SSNM quantity (during an inventory period) greater than 25 percent of the active 

inventory, regardless of its contribution to the SEID. The minimum number of control standard 

measurements can be reduced to eight for nonkey measurement systems that measure from 

10 to 25 percent of the active inventory. The minimum number of control standard 

measurements can be further reduced to four, respectively, for those nonkey systems used to 

measure less than 10 percent of the active inventory quantity.

Key measurement systems for the current inventory period are any set of designated 

measurement systems (of the licensee’s choosing) which, based on the most recent previous 

period, account for at least 90 percent of the total measurement variance contribution to the 

SEID. The set of key measurement systems should include any system utilized to measure an 

SNM/SSNM quantity (during an inventory period) greater than 25 percent of the active 

inventory, regardless of its contribution to the SEID. 

Control standards should be representative of the process material or items being measured

with respect to matrix and SNM/SSNM concentration, unless it can be demonstrated that the 

nonrepresentative aspects have a negligible impact because measurement results are 

unbiased. To be representative, the standards need not always be identical to the process 

unknowns, but any constituent of the process material or any factor associated with a process 

item that produces a bias effect on the measurement should be present to the same degree as 

in the control standards. For scales used to weigh very large items, the control standard 

weights should be artifact standards (e.g., both empty and full containers) of certified mass to 

avoid a bias effect caused by buoyancy or point loading.

The licensee should maintain control measures that will ensure or confirm the continuing validity 

of standards’ assigned values. Examples of the types of controls that would be appropriate 

include the following:

• storage of metal standard weights in a noncorrosive atmosphere

• tamper-safing of NDA standards immediately after makeup

• storage of solution standards in more than one container when usage will be over an 

extended time period (e.g., 1 month),

• storage of standards with an affinity for moisture in a desiccator

• remeasurement of the standard to confirm that its value has not changed

For each measurement system that is not point calibrated, the MC&A plan should identify and 

describe the control standards to be used for control standard measurements. Along with 

material composition and matrix factors, changes in (among other things) temperature, humidity, 

line voltage, and background radiation can also induce biases. Biases also can be operator or 
NUREG-1280, Revision 2 70

analyst induced. Therefore, the scheduling of control standard measurements should be based 

on the following considerations:

• Does the variation between analysts or operators need to be considered and monitored?

• Can environmental variables contribute to measurement bias?

• Is bias likely to vary with respect to the time of day?

• Is a particular bias likely to be long term, short term, or cyclic in nature?

• Is bias a function of the process measurement values over the range of calibration (i.e., 

is the relative percent bias nonuniform over the range of calibration)?

• What controls or procedures are needed to ensure that sampling or aliquoting of the 

control standard is representative of the sampling or aliquoting of the process material?

• To estimate the bias for each measurement system, how much alike, in terms of 

chemical composition, uranium concentration, density, homogeneity, and impurity

content, should the control standards be relative to the process unknowns?

8.4 Replicate Sampling

For systems involving sampling, duplicate measurements performed on single samples or 

measurements of replicate samples, or both, are necessary to estimate the combined analytical 

plus sampling random error. For nonsampling measurement systems, such as NDA and weight 

measurement systems, the random measurement variance component can be derived either 

from (1) replicate measurements performed on process items or (2) the data generated from the 

measurement of control standards.

The licensee should ensure that replicate samples are independent of one another. The 

number of replicate samples measured for each analytical measurement system that is 

designated as a key measurement system during an inventory period should be equal to one of 

the following:

(1) 100 percent of the accountability batches sampled (when less than 15 batches)

(2) the greater of 15 samples or 15 percent of the accountability batches sampled

(3) 50 samples (when 15 percent of the batches is greater than 50)

For nonkey analytical measurement systems, the minimum number of replicate samples to be 

measured during an inventory period should be equal to one of the following:

(4) 100 percent of the accountability batches sampled (when less than eight batches)

(5) the greater of eight samples or 10 percent of the accountability batches sampled

(6) 25 samples (when 10 percent of the batches is greater than 25)
71 NUREG-1280, Revision 2

For each measurement system involving sampling and analysis, the MC&A plan should indicate 

(1) the number of samples taken and measured for each accountability batch measurement and 

(2) the number of analyses performed on each accountability sample. If two or more samples 

are used and one or more analyses per sample are performed for each accountability batch 

measurement, replicate requirements are automatically met. If, however, one sample per batch 

is normally used for accountability purposes, the replicate program should include a periodic 

taking of a second (i.e., replicate) sample. For NDA and mass (weight) measurement systems, 

replicate data can be obtained either from the repeat measurements on production items or by 

using the data generated from the control standard program. That is, each consecutive pair of 

control standard measurements (for a given NDA or mass system) can be regarded as a 

replicate pair. 

The minimum number of replicate measurements performed during an inventory period for a 

given key NDA or mass system should be as given in items (1), (2), or (3), above, except that 

the numbers or percentages are in terms of items measured, rather than batches sampled. 

Likewise, for nonkey NDA and mass measurement systems, the minimum number of replicate 

measurements should be as given in items (4), (5), or (6) above. The scatter in the repeat 

measurements is used to estimate the random error variance using a statistical technique 

known as the one-way analysis of variance. (The NRC recommends the statistical methods 

described in Bowen and Bennett (1988) for satisfying the statistical requirements of 

10 CFR 74.59(e); see also Chapter 9 of this document.) Replication not only improves the 

precision of results obtained from the statistical analysis of the measurement data, but it can 

also detect gross errors in the data. 

8.5 Control Limits

The methods of monitoring and controlling measurement performance should be adequate to 

ensure the reliability of the measurement systems used for MC&A purposes. Examples of 

acceptable methods include control charts and automated data analysis performed on an 

ongoing basis. The proposed method should be capable of providing timely information on the 

control status of measurement systems, including the possible presence of unacceptable 

trends.

The licensee is to establish and use both 0.05 (warning) and 0.001 (out-of-control) limits for 

control standard measurements for those measurement systems used for nuclear material 

accountability, in accordance with 10 CFR 74.59(e)(8). The licensee is also to use 

out-of-control limits for replicate measurements and measurement of replicate samples. 

However, warning limits are optional for the replicate program. For point-calibrated systems, 

the assigned value of the standards measured along with the unknowns is assumed to be valid. 

If the standard’s true value could change because of factors such as evaporation, moisture 

pickup, or oxidation, the value of the standard should be checked periodically. Therefore, 

control limits for the verification measurements associated with such standards should be 

established. This is especially true for those point-calibrated systems that use a single 

standard, or aliquots from a single standard, over any extended period of time. 

When a system generates a control measurement that falls beyond an out-of-control limit, the 

system should not be used for accounting purposes until it has been brought back into control 

(i.e., within the upper and lower warning limit).
NUREG-1280, Revision 2 72

Control limits should be recalculated at a predetermined frequency and modified if necessary. 

The MC&A plan should clearly explain how control limits are established and the frequency for 

redetermining them.

8.5.1 Measurement Control Data Analysis

The licensee should plot measurement control data, such as control standard measurement 

results and the differences between measurement values of replicate pairs, to generate control 

charts. The licensee should review all control charts at least once every 2 weeks unless a 

measurement system was not used during that period. The review should assess the frequency 

of control data exceeding either the warning or the out-of-control limits and also provide an 

evaluation for any significant trends.

8.5.2 Response Actions

Either the analyst or the operator performing a control measurement or his or her supervisor 

should have the responsibility for promptly reporting any control measurement that exceeds an 

out-of-control limit. Such reporting should be made to the measurement control system

manager (or his or her designee), who should have the responsibility and authority to carry out 

or direct the necessary response and corrective actions.

The MC&A plan should clearly define the minimum response and minimum corrective action 

requirements. In addition, the measurement control manager (or his or her designee) should be 

responsible for, and have the authority for, determining and executing additional response and 

corrective actions as deemed appropriate.

The minimum response to a reported incident of a control measurement exceeding an 

out-of-control limit should consist of the following:

(1) verifying that the measurement system in question has been taken out of service with 

respect to accountability measurements

(2) documenting the occurrence of the event

(3) performing at least two additional control measurements

(4) performing additional control measurements, if the results of item (3) do not show the 

system to be back in control, using a different control standard or different replicate 

sample (as appropriate) or recalibrating the measurement system, or making any 

necessary system repairs

(5) reviewing measurements performed on the system in question since the last in-control 

run to determine whether any items should be remeasured

For those measurement systems that make a significant contribution to the SEID, the response 

to an out-of-control condition should also include the remeasurement of any samples (or items) 

that were measured before the out-of-control condition but after the last in-control 

measurement. The validity of the previous measurements can be established without a 

complete remeasurement of all the samples (or items) involved if remeasurement on a “last in, 

first out” basis is used. That is, the last sample (or item) measured before the out-of-control 

measurement, should be the first to be remeasured continuing in reverse order until two 
73 NUREG-1280, Revision 2

consecutive remeasurements are found to be in agreement with their initial measurement at the 

95-percent confidence level.

The MC&A plan should describe specific measurement control system elements applicable to 

those measurement systems used for detection and response purposes. The estimated 

standard deviations of the material control test statistics are derived from the monitoring

program data that are collected in such a manner that they represent the current performance of 

the process and measurement systems. Values obtained when the process is operating in an 

abnormal manner or when a significant process upset or anomaly has occurred will not be 

included in the data used to estimate the standard deviation. However, data are discarded only 

on the basis of preestablished objective criteria. Data may not be pooled over periods of time 

when significant process or measurement system changes have occurred. When data pooling is 

appropriate, statistical tests will be applied to demonstrate that the means and variances are 

from the same distribution at the 0.05-level of significance. The data will be tested for 

randomness (see Jaech (1977), Section 2.9-2, and Bowen and Bennett (1988)) and normality 

when tests, such as the F-test on variances, are distribution dependent.

The quality control program for monitoring detection system effectiveness should have as its 

key goal assurance that the estimates of standard deviations used in establishing action 

thresholds that comply with the detection probability criteria neither underestimate nor 

overestimate the true standard deviations of the tests. It is important to ensure that the estimate 

of the mean and standard deviation for each material control test reflects the actual operating 

conditions and error sources. Generally this is done by calculating these estimates from sets of 

material control test data, but it is very important to avoid serious inflation of the variability of the 

data that would result in the event of actual losses of SSNM or out-of-control process variables. 

Therefore, both the measurement component and the overall standard deviation should be 

monitored for diagnostic purposes. Failure to consider all sources of noncorrectable variation, 

including normal process variations, would result in an unrealistically small estimate. Use of too 

small of an estimate could result in an action threshold being set too high to provide the loss 

detection probability required by 10 CFR 74.53.

The standard deviation of each material control test statistic is periodically checked by 

comparing an estimate of the current standard deviation with the prior value used in setting the 

alarm threshold. The estimate of the current standard deviation will be based on at least the 

10 most recent values of a test statistic, whereas the reference value will be based on at least 

20 values.

8.6 Commitments and Acceptance Criteria

In its MC&A plan, the licensee should provide definitive commitments that adhere to the 

regulatory requirements and meet acceptance criteria applicable to measurement control. A 

finding that the licensee’s MC&A plan for measurement control is acceptable and in accordance 

with 10 CFR 74.59(e) will be based on, but not limited to, the following acceptance criteria:

• The measurement control system produces data that are representative of actual 

operating conditions and all errors that impact the ID estimate. The larger uncertainty 

estimates that collectively contribute 90 percent or more to the SEID will be based on a 

minimum of 15 standard or replicate process material measurements, as appropriate.
NUREG-1280, Revision 2 74

• The method to be used for estimating the SEID for the typical material balance, as 

shown in the annex to the MC&A plan, should meet the following criteria:

– All reasonable and probable sources of measurement error for the key 

measurement systems affecting IDs are included.

– The selection of the key measurements whose variances are to be included in 

calculating the standard error is justified by an analysis of the relative magnitudes 

of the variance components of a typical ID and their comparative effect on the 

SEID.

– Any measurement error standard deviations not actually determined by the 

measurement control program are shown to be reasonable either by comparison 

with published state-of-the-art measurement performance in similar applications

(see such sources as Rogers (1983)1

) or with records of past performance data 

from the licensee’s facility. Records showing these data must be available to the 

NRC.

– The calculation of the SEID is performed in accordance with a recognized error 

propagation method. Such methods have been published in Bowen and Bennett

(1988), Jaech (1973), and the International Atomic Energy Agency’s (IAEA’s) 

handbook on statistical concepts.

• Responsibility is assigned for planning, developing, coordinating, and administering a 

measurement control program to an individual who has no direct responsibility for either 

performing measurements or for SNM/SSNM processing or handling and who holds a 

position at an organizational level that permits independence of action and has adequate 

authority to obtain all of the information needed to monitor and evaluate measurement 

quality as required by 10 CFR 74.59(e).

• Any contractor who performs MC&A measurement services conforms with applicable 

requirements in 10 CFR 74.59(d) and 10 CFR 74.59(e). Conformance should include 

reporting by the contractor of sufficient measurement control data to allow the licensee 

to calculate bias corrections and the standard error of the bias estimator.

• Potential sources of sampling error are identified and process sampling tests using 

well-characterized materials to establish or verify the applicability of utilized procedures 

for sampling SNM/SSNM and for maintaining sample integrity during transport and 

storage are used to ensure that the samples accurately represent the material being 

sampled. Such sampling tests or sample integrity tests, as appropriate, should be 

conducted whenever the following occurs:

– A new sampling procedure or technique is utilized or new sampling equipment is 

installed.

 

1 For example, Rogers (1983) cites performance relative standard deviations of 0.65 percent for random error 

and 0.018 percent for systematic error using the Davies and Gray titrimetric method for measuring TRIGA 

alloy process material. For the determination of plutonium by redox (oxidation-reduction reactions) titrimetry, 

the relative standard deviations were 0.38 percent for random error and 0.038 percent for systematic error in 

the measurement of plutonium metal.
75 NUREG-1280, Revision 2

– A sampling procedure, technique, or sampling equipment is modified.

– Sample containers, sample transport methods, or sample storage conditions are 

changed or modified.

• Current data are generated on the performance of each measurement system utilized for 

establishing measured values during an inventory period, including estimates of bias, 

variance components for calibration, sampling, and repeat measurements (of the same 

sample). The program data should reflect the current process and measurement 

conditions existing at the time the control measurements are made.

• Standards are used on an ongoing basis for the calibration and control of all bulk mass, 

NDA, and analytical measurement systems utilized for SNM/SSNM accountability. 

Calibrations should be repeated whenever a significant change occurs in a 

measurement system or when program data indicate a need for recalibration. A need 

for recalibration is identified by submitting blend standards as regular assay samples. 

Calibrations and control standard measurements should be based on standards whose 

assigned values are traceable to certified reference standards or certified standard 

reference materials. Additionally, control standards should be representative of the 

process material or items being measured by the measurement system in question.

• Control measurements are conducted to provide current data for the determination of 

random error behavior. On a predetermined schedule, the program should include, as 

appropriate, the following:

– replicate analyses of individual samples

– analysis of replicate process samples

– replicate volume measurements of bulk process batches

– replicate weight measurements of process items and bulk batches or,

alternatively, the use of data generated from the replicate weighings of control 

standard weights as derived from the control standard program

– replicate NDA measurements of individual process containers (items) or,

alternatively, the use of data generated from the replicate measurements of NDA 

control standards as derived from the control standard program

• Program data are collected on the performance of each measurement system utilized 

during the current material balance period, including estimates of bias, variance 

components for calibration, sampling, and repeat measurements (of the same sample).

• Measurement system data are periodically evaluated, so that if the SEID exceeds 

established limits, the effect that has caused the SEID to be too large can be identified.

• An investigation is promptly initiated and appropriate corrective action is taken whenever 

a control data point exceeds the control limit of 0.05; whenever a control data point

exceeds the control limit of 0.001, the measurement system that generated the data

should immediately be placed out of service with respect to MC&A measurements until 
NUREG-1280, Revision 2 76

the deficiency has been corrected and the system brought into control with the 

0.05 control limits.

• The approach used for bounding the total measurement standard error for a typical 

material balance period should meet the following criteria:

– All reasonable and probable sources of measurement error affecting ID are 

included.

– Any assumed measurement standard deviations are shown to be reasonable. 

They may be shown to be reasonable by comparison to either records of the 

licensee’s past performance data or to published measurement performance in 

similar applications.

– The calculation of the total measurement standard error is performed in 

accordance with a recognized error propagation method. Such methods have 

been published by Jaech (1973), Lumb and Tingey (1981), IAEA (1998), and 

Bowen and Bennett (1988).

• The licensee will confirm that the accountability measurements provided by a contractor 

are controlled by a measurement control program and that the contractor’s 

measurement control program is adequate by conducting audit and assessment reviews 

of the contractor’s program at intervals not to exceed 12 months.

• A measurement control program is followed by which all measurement biases 

associated with key measurement systems are estimated and any significant biases are 

eliminated from ID values and shipper-receiver differences.

• The calculation of the measurement contributions to the SEID are traceable to the 

appropriate measurement error data and to the calibration standards used.

• The measurement systems have adequate calibration frequencies, sufficient control of 

biases, and sufficiently small standard deviations to achieve the requirements of 

10 CFR 74.51(c). A measurement control program is used by both in-house activities 

and any contractor who performs MC&A measurement services for the licensee to 

ensure that the quality of the measurements is maintained on a level consistent with the 

NRC requirements in 10 CFR Part 74.

• Analyses and evaluations are performed on the design, installation, preoperational 

testing, calibration, and operation of all measurement systems to be used for MC&A 

purposes.

• Process and engineering tests are performed, using well-characterized materials, to 

verify the applicability of mixing and sampling procedures for SNM/SSNM and to ensure 

sample validity during transport and storage.

• Current data are generated during the inventory period for establishing bias correction 

values, uncertainties on calibration factors, and random error variances.
77 NUREG-1280, Revision 2

• Bias corrections are applied to individual items whenever a bias estimate exceeds twice 

the estimated standard deviation of the estimator and the rounding error of affected 

items. Otherwise, the impact of biases is applied as a correction to the ID. Bias 

correction adjustments to ID are not entered in the accounting ledgers.

• When a statistically significant change occurs in the estimated standard deviation of a 

material control test statistic, the alarm threshold of the test is adjusted as necessary to 

ensure that a goal quantity loss of SSNM will be detected with the probability required by 

10 CFR 74.53(b)(2). Additionally, the change will be investigated to determine the 

cause.

• Contractors who perform MC&A measurement services will implement and maintain a 

control program for measurement control and human errors. The program will be of 

sufficient depth and intensity to preclude any degradation of the MC&A system.

• The estimated standard deviations of the material control test statistics are maintained at 

or below a level sufficient to achieve the loss detection capabilities established under

10 CFR 74.53(b) without incurring an excessive rate of false alarms. 

• A statistical control system is maintained to ensure that measurements employed for 

MC&A purposes are obtained from measurement systems that are in a state of statistical 

control. Control limits are established at the 0.05 and 0.001 levels of significance.

• When a process modification occurs, sufficient data are generated to provide a reliable 

estimate of the standard deviation applicable to the material control test.

• The magnitude of the uncertainties associated with the process variabilities is 

determined and applied in the overall uncertainty (standard deviation) utilized in 

establishing alarm thresholds.

• The cumulative shipper-receiver differences for each like material type are routinely 

monitored and when, for any consecutive 6-month period, they are determined to be

statistically significant and exceed the larger of 1 FKG or 0.1 percent of the quantity 

received, corrective action is taken to identify and correct measurement biases.

• The methods used to estimate the SEID and the cumulative shipper-receiver differences

will be based on commonly accepted principles.

• Current inventory period control data are used to estimate the SEID and the standard 

deviations associated with the process differences. Data generated in immediately 

preceding material balance periods may be combined with current data when it can be 

demonstrated that the data are from the same distribution and the combined data are 

utilized to establish current period measurement uncertainty values.

79 NUREG-1280, Revision 2

9. STATISTICS

9.0 Regulatory Intent

Proper use of statistics is important to ensuring that the regulatory requirements in 

10 CFR 74.51, 10 CFR 74.53, 10 CFR 74.55, 10 CFR 74.57, and 10 CFR 74.59 are met. An 

effective statistical program will ensure that measurement systems perform within control limits, 

measurement uncertainties are calculated and propagated, the ID and SEID are determined, 

and significant shipper-receiver differences are identified. For example, 10 CFR 74.59(f)(1)(i) 

requires licensees to calculate the ID and SEID for the material balance period terminated by 

each physical inventory. Proper use of statistics is important to correctly propagate the 

uncertainties from all measurements into an accurate SEID value.

9.1 Determination of Measurement Uncertainties

To achieve the objectives and capabilities of 10 CFR 74.3 and 10 CFR 74.51, each licensee or 

applicant should institute a statistical program that evaluates the MC&A data to ensure that 

(1) the measurement data are analyzed in a rigorous manner and (2) statistical tests and 

inferences concerning the status of the nuclear material possessed are appropriately tested. 

The NRC sponsored the development of a comprehensive reference that specifically addresses 

the statistical treatment of MC&A data. The NRC recommends the statistical methods 

described in Bowen and Bennett (1988) for satisfying the statistical requirements of 

10 CFR 74.53, 10 CFR 74.55, and 10 CFR 74.59. 

The MC&A plan should do the following:

• Contain a detailed discussion of the procedures and methodologies for estimating 

measurement variance components.

• Discuss how biases are determined and how bias corrections are applied, considering 

the following:

– how often biases are estimated

– how the bias’ effect on the measured quantity of material in an item is determined

– when and how bias corrections to items are made

– how their effect on ID is determined

– when and how bias corrections are applied to the ID

• Describe the procedure and means for determining active inventory.

• Provide all relevant information regarding the determination of the SEID.

• Specify the methodology for determining ID threshold values. (See Chapter 10 of this 

document for additional information on ID limits and response actions.)
NUREG-1280, Revision 2 80

Error variances associated with calibrations should be determined and applied in accordance 

with the following:

• For point calibrations, in which a standard is measured with each unknown, the 

uncertainty associated with the standard measurement is treated as a random error, 

while the uncertainty associated with the standard’s assigned value is treated as a fixed 

error.

• For point calibrations, in which standards are run before and after a group of process 

samples and the average measured value of the standards is utilized in the element or 

isotope determination, the uncertainty associated with the standard’s average measured 

value is treated as a fixed error for the group of process samples.

• For line or curve calibrations, the uncertainty associated with the calibration parameters 

is treated as a fixed error.

The estimated standard deviations of the material control test statistics should be derived from 

the monitoring program data that are collected in such a manner that they represent the current 

performance of the process and measurement systems. Values obtained when the process is 

operating in an abnormal manner or when a significant process upset or anomaly has occurred 

should not be included in the data used to estimate the standard deviation. However, data 

should be discarded only on the basis of preestablished objective criteria. Data should not be 

pooled over periods of time when significant process or measurement system changes have 

occurred. When data pooling is appropriate, statistical tests should be applied to demonstrate 

that the means and variances are from the same distribution at the 0.05 level of significance. 

The data should be tested for randomness (see Jaech (1977), Section 2.9-2, and Bowen and 

Bennett (1988)) and normality when tests, such as the F-test on variances, are distribution 

dependent.

The quality control program for monitoring detection system effectiveness should have as its 

key goal assurance that the estimates of standard deviations used in establishing action 

thresholds that comply with the detection probability criteria neither underestimate nor 

overestimate the true standard deviations of the tests. It is important to ensure that the estimate

of the mean and standard deviation for each material control test reflects the actual operating 

conditions and error sources. Generally this is done by calculating these estimates from sets of 

material control test data, but it is very important to avoid serious inflation of the variability of the 

data that would result in the event of actual losses of SNM/SSNM or out-of-control process 

variables. Therefore, both the measurement component and the overall standard deviation 

should be monitored for diagnostic purposes. Failure to consider all sources of noncorrectable 

variation, including normal process variations, would result in an unrealistically small estimate. 

Use of too small an estimate could result in an action threshold being set too high to provide the 

required loss detection probability.

The standard deviation of each material control test statistic should be periodically checked by 

comparing an estimate of the current standard deviation with the prior value used in setting the 

alarm threshold. The estimate of the current standard deviation will be based on at least the 

10 most recent values of a test statistic, whereas the reference value will be based on at least 

20 values.
81 NUREG-1280, Revision 2

9.2 Determination of the Standard Error of Inventory Difference

As defined in 10 CFR 74.4, “Definitions,” the “standard error of inventory difference” means the 

standard deviation of an ID that takes into account all measurement error contributions to the 

components of the ID. Including all measurement uncertainties, the SEID (for either uranium, 

U-235, plutonium, or U-233, as applicable) can be expressed as follows:

SEID = 

where

k = number of measurement systems

Gi = total grams uranium (or U-235) measured during inventory period by 

measurement system i

(σi)s = systematic error standard deviation for measurement system i

(σi)r = random error standard deviation for measurement system i

n = number of batches (items) measured by measurement system i

In theory, the SEID provides the uncertainty, at the 67-percent confidence level, of the ID 

estimate.

The MC&A plan should provide all relevant information regarding the determination of the SEID. 

The plan should include a commitment that at least two individuals independently verify the 

correctness of the SEID calculation for each total plant material balance. If the SEID value is 

calculated by a computer, the verification by two or more persons involves ensuring that the 

input data used by the computer to calculate the SEID was correct.

The method to be used for estimating the SEID for the typical material balance, as shown in the 

annex to the MC&A plan, should be consistent with the following criteria:

• All reasonable and probable sources of measurement error for the key measurement 

systems affecting IDs are included.

• The selection of the key measurements whose variances are to be included in 

calculating the standard error is justified by an analysis of the relative magnitudes of the 

variance components of a typical ID and their comparative effect on the SEID.

• Any measurement error standard deviations not actually determined by the 

measurement control program are shown to be reasonable either by comparison with 

published state-of-the-art measurement performance in similar applications (see such 

sources as Rogers (1983) and Reilly and Evans (1977)) or with records of past 

performance data from the licensee’s facility. Records showing these data should be 

available to the NRC.

• The calculation of the SEID is performed in accordance with a recognized error 

propagation method. Such methods have been published by Jaech (1973) and the IAEA 

(1998).
NUREG-1280, Revision 2 82

9.3 Bias Corrections

From a statistical perspective, biases that are not statistically significant (at the 95-percent 

confidence level) should never be applied as adjustments (corrections) to the accounting 

records. To obtain the best estimate of the true ID value, such insignificant biases should be 

applied as a nonaccounting adjustment to the initially calculated ID (as obtained from the ID 

equation: ID = BI + A − R − EI, where BI is the beginning inventory, A is additions to the 

inventory, R is removals from the inventory, and EI is the ending inventory). Such practice is

not deemed necessary, however, for material balances pertaining to SNM of moderate strategic 

significance and is thus optional.

For biases that are statistically significant (at the 95-percent confidence level), it is common 

practice to adjust the accounting values for individual items if the bias effect (as grams element 

and grams isotope) on the item is more than the rounding error for that item and, if less than the 

rounding error, to apply the bias as a nonaccounting adjustment to the ID. Under a 

well-designed and well-managed measurement control system, bias corrections to the 

accounting records should seldom, if ever, be necessary under the above-mentioned approach. 

Although the effect on an individual item from a statistically significant bias should be negligible, 

the effect of that bias across hundreds or thousands of items (whose SNM/SSNM values were 

derived from the biased measurement system) could have a very significant impact on the ID 

value.

Nevertheless, in view of the very large quantity of SNM/SSNM that is of a safeguards 

significance, the NRC acceptance criteria does not normally call for applying bias corrections to 

either the accounting records or as an adjustment to ID unless the effect of a single significant 

bias or the net sum of all significant biases is unusually large.

At a minimum, to be consistent with the NRC acceptance criteria, a bias correction for a single 

key measurement system should be considered “significant,” and thus applied either as 

corrections to the accounting records or as an adjustment to the ID if (1) such bias is statistically 

significant at the 95-percent confidence level and (2) either or both of the following conditions 

are also true:

(1) Applying the correction would cause the ID to exceed three times the SEID.

(2) The bias is greater than 0.0100 percent relative.

Additionally, the net algebraic sum (expressed as grams SNM/SSNM) of all statistically 

significant (95-percent confidence level) biases from key measurement systems not defined as 

bias free, and which have not been applied as a correction/adjustment under condition (1) or (2)

above, is statistically significant and is to be applied as a net adjustment to the ID if applying 

such correction would cause the ID to exceed three times the SEID.
83 NUREG-1280, Revision 2

The licensee should monitor all measurement systems affecting a material control test, ID 

estimate, or shipper-receiver comparison for bias, except as noted below. The intensity of the 

monitoring program is proportional to the significance of the measurement system for the test 

involved. The key measurement systems (i.e., those that contribute at least 10 percent of the 

estimated measurement standard deviation of a material control test, a shipper-receiver 

difference, or an ID estimator) should be tested for bias at least monthly except in the following 

circumstances:

• The measurement system has been demonstrated to be quite stable and the results 

predictable.

• The bias estimate of a measurement system utilized solely for material control test 

affects inputs and outputs equally and therefore the effects of bias cancel.

• The bias estimate for a measurement system utilized solely for material control test is 

shown to be constant and does not impact the material control test.

• The system is defined as bias free.

When the above conditions exist, the bias tests can be extended to 3 months or exempted 

altogether if the system qualifies as bias free.

The bias tests should be made using the mean of at least eight control standard measurements. 

Bias corrections should be made to individual items if the bias exceeds twice the standard 

deviation of its estimator and the rounding error of affected items. Otherwise, bias corrections 

should be applied as corrections to the ID, unless the net sum of such biases is less than

50 grams of SSNM, in which case no correction to the ID is necessary.

All other measurement systems (unless bias free) should be monitored for bias and tested every 

3 months except for those measurement systems involved with movement of material across 

the MAA boundary and a cross-check measurement is not performed. Such systems should

also be tested monthly.

Measurement systems are statistically “bias free” if a representative standard is run for each 

unknown or set of unknowns measured at the same time or representative standards are 

measured before or after a group of process samples and the standards measurement 

response and assigned value, rather than any previous calibration information, are used in 

determining the value of the unknowns.

85 NUREG-1280, Revision 2

10. PHYSICAL INVENTORIES

10.0 Regulatory Intent

The intent of the 10 CFR 74.59(f) physical inventory requirements is to ensure that licensees 

maintain inventory control and conduct physical inventories at intervals not to exceed 6 calendar 

months to confirm that a loss, theft, or diversion of an SQ of SNM/SSNM has not occurred. 

Periodic physical inventories enable a licensee to adjust accounts to accurately reflect the 

status of the SNM/SSNM inventory within a facility. Comparisons of the book inventory to the 

physical inventory (i.e., the ID) also serve as a quality control check on the performance of the 

material control tests employed for prompt loss detection. The subdivision of a facility into 

multiple process units and the performance of material control tests will enhance the resolution 

of significant IDs through better loss localization capability. Additionally, material control test 

results will be useful in pinpointing the time when an anomaly likely occurred.

10.1 General Description

The applicant or licensee should provide a general description of how physical inventories of the 

plant will be planned, conducted, assessed, and reported. 

The MC&A plan should contain a definitive statement that physical inventory functions and 

responsibilities are reviewed comprehensively with the involved individuals before the start of 

each physical inventory. 

A book inventory listing, derived from the MC&A record system, should be generated just before 

the actual start of each physical inventory; such listing shall include all of the SNM/SSNM that 

the records indicate the licensee possesses at the inventory cutoff time.

The regulations in 10 CFR 74.59(f) require a licensee to conduct a physical inventory. The 

licensee is to report the ID and related information associated with each physical inventory to 

the NRC on NRC Form 327, in accordance with 10 CFR 74.17, “Special Nuclear Material 

Physical Inventory Summary Report.” In addition, if any material associated with material codes 

20-E2 (i.e., moderately enriched uranium), 20-E1 (i.e., low-enriched uranium), 70 (U-233), 50 

(plutonium), or 83 (Pu-238) is possessed by the licensee, such material is subject to the 

physical inventory requirements. The licensee should report each material code ID and 

associated information on separate NRC 327 forms.

10.2 Organization, Procedures, and Schedules

The MC&A plan should explain the makeup and duties of the typical physical inventory 

organization. The plan should identify the individual having responsibility for the coordination of 

the physical inventory effort by position title. The MC&A plan also should indicate how the 

preparation and modification of inventory procedures are controlled. 

The MC&A plan should contain a definitive statement that specific inventory instructions are 

prepared and issued for each physical inventory.
NUREG-1280, Revision 2 86

10.3 Description of Typical Item Strata

The MC&A plan should describe the expected item population in terms of the following:

• type of item (i.e., stratum)

• expected range of the number of items within each stratum

• the average elemental and isotopic content of the items within each stratum

• the expected rate of item generation and consumption for each stratum

10.4 Facility Preparation

The MC&A plan should describe the preparation of the facility for physical inventory. The 

description should include the following:

• the basic approach to facility preparation (e.g., draindown, cleanout)

• the degree to which any inventory prelisting will be utilized and the means of verifying 

the prelisted items

• the means of controlling inventory listing forms and tags

• the cutoff procedures for SNM/SSNM processing, transfers, and records adjustments to 

ensure an accurate recording of material transactions and inventory listing

• the organization of the inventory teams, including the cross-checks to prevent 

falsification and minimize mistakes

• the criteria, controls, and procedures for tamper-safing containers or vaults whose 

SNM/SSNM content (as established by prior measurement) will be accepted for 

inventory

10.5 Conducting Physical Inventories

The MC&A plan should describe how physical inventories are conducted. The description 

should address the following:

• the technique to ensure that all SNM/SSNM is inventoried and none is counted more 

than once

• the measurements that will be performed specifically for inventory purposes

• the use of prior measurement data, factors, and composite data

• the degree to which process holdup will be cleaned out and the measurement of residual 

holdup
87 NUREG-1280, Revision 2

• the use of post-inventory inspection techniques (if employed)

The annex to the MC&A plan should include an example of a typical inventory listing by material 

type and quantity.

The plan should address the means for measuring or estimating residual process material (i.e., 

holdup) in detail. The plan should also discuss the change or variation in such deposited holdup 

from one physical inventory to the next.

The licensee should prepare a detailed inventory notice for each physical inventory. The notice 

should be issued to all involved parties and should contain instructions that define the timing 

and performance of various inventory steps and conditions under which the inventory is to be 

taken. Specific sampling points throughout the process and instructions on data submission to 

the accountability organization should be identified. The instructions should highlight any 

required deviation from normal inventory procedures contained in the plant’s operating 

procedures. 

The MC&A plan should describe the procedures and methodologies associated with performing 

physical inventories in sufficient detail to demonstrate that valid physical inventories are 

conducted. Such description should include a general outline of the following:

• organization and separation of functions

• assignment of inventory teams and their training in the use of uniform practices

• obtaining, verifying, and recording of source data

• control of inventory forms

• assurance that item counts verify the presence of each item while preventing any item 

from being counted more than once

• implementation of cutoff and material handling procedures

Decontamination and recovery is a complex operation involving the disassembly and 

decontamination of failed pieces of process equipment and recovery of uranium from various 

types of scrap materials. The basic inventory procedure should involve establishing a cutoff of 

movement of materials into the area and processing all materials to a measurable form, such as 

containers of solution or oxide. Except for the decontamination enclosure in which in-process 

solutions are mixed, sampled, and measured volumetrically, the inventory process should 

involve emptying and flushing process systems and piping, which then could be measured using 

NDA techniques to establish levels of residual holdup, if such holdup is significant.

The MC&A plan should describe special item storage and handling or tamper-indicating 

methods, which are used to ensure that the previously measured and recorded SNM/SSNM 

content values can be used for inventory purposes without remeasurement. In addition, the 

MC&A plan should outline how item identities are verified and how tampering with the contents 

of items will be detected or prevented. 
NUREG-1280, Revision 2 88

Items that are not encapsulated, affixed with TIDs, or otherwise protected to ensure the validity 

of prior measurements need special attention. The MC&A plan should present the basis for 

determining which items are to be measured at physical inventory time and the justification of 

any proposed alternatives to measurement of any SNM/SSNM included in the inventory. If 

statistical sampling is proposed as an alternative method to 100-percent verification, the MC&A

plan should describe the sampling plan. Such description should include the following:

• the method of segregating the types of items to be sampled (i.e., selected for 

remeasurement)

• the procedure for calculating the sample size (i.e., the number of items) for each stratum

• the parameter to be measured (e.g., gross weight or total U-235 content)

• the quality of the measurement methods used to verify original measurement values (for 

the parameter being measured)

• the procedure for reconciling discrepancies between original and remeasurement values 

and for scheduling additional tests and remeasurements

• the basis for discarding an original SNM/SSNM value and replacing it with a 

remeasurement value

The following equation describes one acceptable means for establishing the number of items to 

be randomly selected for remeasurement from a particular stratum to achieve the required 

90-percent power of detecting a loss of an SQ:

n = N [1 (0.10)x/g]

where

n = number of items to be remeasured

N = total number of items in the stratum

x = maximum SNM/SSNM content per item (kilograms)

g = SQ = significant quantity for statistical sampling plans, which is either 1 FKG

of SSNM or 10,000 grams of U-235 contained in uranium enriched to 

10 percent or more but less than 20 percent

When using such a statistical sampling plan to confirm the validity of prior measurements, the 

remeasurement value obtained for each item (among the n items remeasured) must be 

compared to its original value. If the difference for a given item exceeds some predetermined 

limit (usually three times the standard deviation of the measurement, or 3 sigma), that item is 

designated as a “defect.” To achieve the 90-percent power of detection capability for detecting 

a loss as small as SQ, there must be at least a 90-percent probability that one or more defects 

will be encountered among the items remeasured across all involved strata if an actual loss of 

an SQ has occurred. If across all strata one or more defects are encountered, a second set of n

randomly selected items (or all remaining items if n = 0.5 N) from each stratum should be 

remeasured. If one or more defects are encountered (across all item strata) while performing 
89 NUREG-1280, Revision 2

any second round of remeasurements, all unsealed and unencapsulated items not yet 

remeasured should be remeasured. Any item, regardless of whether there are any defects, 

whose remeasured value differs from its original measurement by more than two sigma (2σ) 

should have its accounting value revised to reflect its remeasured quantity.

The MC&A plan should also contain a definitive statement that all items on ending inventory that 

have not been previously measured are measured for inventory purposes.

The MC&A plan should present the decision rationale for determining when the element and 

isotope factors for items, objects, or containers are measured directly for inventory and when 

they may be based on other measurements. For example, if the U-235 contained in liquid 

waste batches is derived by applying an average enrichment factor to the measured uranium 

element content, the plan should discuss the rationale for such practice (as opposed to 

measuring each batch for both uranium and U-235 content) and describe the method for 

establishing the average enrichment factor.

If the content of items is established through prior measurements and those items are sealed 

with TIDs or access to them is controlled, the SNM/SSNM quantity in those items may be based 

on those measured values. Otherwise, verification of SNM/SSNM content can be achieved by 

reweighing either (1) all items within a given stratum or (2) randomly selected items from the 

stratum based on a statistical sampling plan. A statistical sampling plan will not be acceptable if 

there is any likelihood of a significant change in the elemental concentration (or weight fraction) 

or in the isotopic distribution because of such factors as oxidation, change in moisture content, 

commingling with materials of different enrichments, or different compositions.

10.6 Inventory Reconciliation

The MC&A plan should describe the reconciliation procedure, including the following:

• the method of calculating the SEID

• the criteria for investigation of IDs that exceed three times the SEID and 200 grams of 

plutonium or U-233 or 300 grams U-235

• the method of establishing three times the standard deviation of historical IDs against 

which an ID that exceeds three times the SEID will be evaluated

• the criteria for establishing the depth of investigation for excessive IDs and the types of 

investigative actions

• the handling of prior period adjustments and measurement system biases that are 

applied as corrections to an ID

• the method of adjusting the book records to the results of the physical inventory

• the means of establishing the active inventory, including the source records that will be 

used in the computation
NUREG-1280, Revision 2 90

10.7 Commitments and Acceptance Criteria

In its MC&A plan, the licensee should provide definitive commitments that adhere to the 

regulatory requirements and meet acceptance criteria applicable to physical inventories. A 

finding that the licensee’s MC&A plan for conducting physical inventories is acceptable and in 

accordance with 10 CFR 74.59(f) will be based on, but not limited to, the following acceptance 

criteria:

• An MC&A system will be maintained that is capable of confirming, at intervals not to 

exceed 6 months, the presence of all SNM/SSNM expected to be present at a given 

time, based on the accounting ledgers, with the possible exception of waste materials 

transferred to (via DOE/NRC Form 741 transactions) and stored in holding accounts.

• Each physical inventory listing will include all SNM/SSNM possessed on the inventory 

date, except for waste materials assigned to holding accounts (in accordance with the 

exception provided in 10 CFR 74.51(a)(2) and DOE/NRC Form 741 instructions). All 

listed SNM/SSNM quantities are to be based on measurements.

• Unique identification for each item on inventory is provided and inventory records are 

maintained showing the identity, location, and quantity of SNM/SSNM for all such items.

• All transfers of SNM/SSNM between designated internal control areas within the 

licensee’s site are documented.

• Discrepancies in the identity, quantity, or location of items, objects, or containers of 

SNM/SSNM that are detected during a physical inventory will be corrected.

• Procedures for tamper-safing containers or vaults containing SNM/SSNM are 

maintained and followed, which include control of access to, and distribution of, unused 

seals and records.

• Procedures for confirming the validity of prior measurements associated with 

unencapsulated and unsealed items on ending inventory are maintained and followed.

• Physical inventory procedures are maintained and followed to ensure the following:

− The quantity of SNM/SSNM associated with each item on ending inventory is a 

measured value.

− Each item on ending inventory is listed and identified to ensure that all items are 

listed more than once.

− Cutoff procedures for transfers and processing are established so that all 

quantities are inventoried and none are inventoried more than once.

− Cutoff procedures for records and reports are established so that all transfers for

the inventory and material balance interval and no others are included in the 

records for the material balance period in question.
91 NUREG-1280, Revision 2

− Upon completion of the physical inventory, all book and inventory records, for 

total plant and individual internal control areas, are reconciled with and adjusted 

to the results of the physical inventory.

− Measurements will be performed for element and fissile isotope on all quantities 

of SNM not previously measured.

• Physical inventories are conducted according to written instructions for each physical 

inventory which do the following:

− Assign inventory duties and responsibilities.

− Specify the extent to which each internal control area and process is to be shut 

down, cleaned out, or remain static.

− Identify the basis for accepting previously made measurements.

− Designate measurements to be made for physical inventory purposes and the 

procedures for making such measurements.

• The individual responsible for the conduct of the physical inventory is either free from 

potential conflicts of interest or is overchecked sufficiently to prevent compromising the 

validity of the physical inventory.

• For each plant, physical inventories are conducted for all possessed SNM/SSNM at 

intervals not to exceed 6 calendar months.

• Within 45 calendar days after the start of each physical inventory required by 

10 CFR 74.59(f)(1)(i) and 10 CFR 74.59(f)(1)(v), the following actions should be taken:

− For the material balance period terminated by the physical inventory, the ID and 

its associated SEID are calculated for both element and fissile isotope with 

respect to each applicable DOE/NRC material type code.

− For each applicable DOE/NRC material type code, the book record of quantity of 

element and fissile isotope is reconciled and adjusted to the results of the 

physical inventory.

− Any SEID estimate 0.100 percent of active inventory and any ID that exceeds 

three times the standard error and 200 grams of plutonium or U-233 or 

300 grams U-235 is investigated and reported to the appropriate safeguards 

organizational unit within the NRC’s Office of Nuclear Material Safety and 

Safeguards.

• As an additional alternative to remeasurement of unsealed SNM/SSNM at physical 

inventory time, a program of routine process monitoring will be acceptable when the 

combination of the process monitoring program and the inventory procedures will 

achieve the same level of loss detection capability as that provided by a physical 

inventory in which all unencapsulated items are either tamper-safed or remeasured.
NUREG-1280, Revision 2 92

• Any previously measured, but unsealed (or unencapsulated) SNM/SSNM that is on hand 

at the time of the physical inventory, and which is to be introduced into subsequent 

processing steps before inventory reconciliation, should be remeasured or have its prior 

measurement value confirmed by an acceptable alternative before the subsequent 

processing is initiated.

• The SNM/SSNM content of groups of like items can be determined by averaging typical 

contents as determined by measurements of representative item samples of that 

material at the time of the inventory, if the licensee demonstrates that the SEID estimator 

includes any additional uncertainty resulting from this averaging method.

• With respect to the processing of scrap generated in a prior period, the current period 

assigned value must be based on dissolver solution and dissolver residue 

measurements and not on the product of the scrap plant. This is because losses may 

occur during the separation and purification stage which should, in fact, be attributable to 

current period processing. Any difference between the prior period value and the value 

obtained from after dissolution plus residue measurements is to be treated as a prior 

period adjustment to the ID for the current period.

• All SNM/SSNM values on the physical inventory listing must be based on 

measurements. Prior measurement values may be accepted for inventory provided they 

were determined on a measurement system subject to the licensee’s measurement 

control program and the containers were either tamper-safed, stored in an area that 

provided protection equivalent to tamper-safing, or encapsulated. Otherwise, the 

previously measured SNM/SSNM content of items on ending inventory must be verified 

by remeasurement.

Adjustments to reconcile the book inventory to the physical inventory will be in accordance with 

commonly accepted accounting practices, and the adjustments will be traceable and auditable.

The effect of prior period adjustments will be taken into account before the significance of the 

current period ID is assessed. Prior period adjustments could result from any of the following:

• corrections of a recording or measurement error associated with material on beginning 

inventory

• resolution within the current period of a statistically significant shipper-receiver difference 

involving material that was on beginning inventory

• an adjustment to the initial receipt value pertaining to scrap, received in a prior period, 

resulting from a better measurement following dissolution of such scrap in the current 

period

The appropriate procedure for dealing with biases not applied to individual items and for prior 

period adjustments is, for purposes of ID evaluation, to modify the ID quantity by adding or 

subtracting a quantity of SNM/SSNM equivalent to the net total of adjustments so as to obtain 

an adjusted ID that reflects the current period ID. ID bias corrections and prior period 

adjustments are not, however, applied as adjustments to the book inventory value.
93 NUREG-1280, Revision 2

Assessment of the significance of current period material balance results by sequential analysis 

of prior period ID data, as required by 10 CFR 74.59(f)(1)(ii) whenever the ID exceeds three

times the SEID, requires consideration of the following relevant points:

• The sequence of IDs used for analysis should possess essentially the same components 

as the current period. That is, the throughputs should be approximately the same (e.g., 

within plus or minus 25 percent), the same process units should be operational, and the 

process should not have undergone any major modifications. With respect to the unit 

operations, it is not essential that all units operate every period but rather that the 

grouping of IDs for analysis take into account which units were operative. As to process 

modifications, a major modification would be one that has a significant impact on 

measurement capabilities or holdup patterns. “Significant” means a change in the SEID 

of plus or minus 30 percent or greater.

• The analysis of a sequence of IDs to establish a representative standard deviation must 

take into account the covariances that exist between adjacent (lag 1) and alternate 

(lag 2) pairs. The AMASS methodology (Lumb and Tingey, 1981) and INDEP (Lumb 

and Associates, 1986) provide two acceptable means of determining the historical 

standard deviations taking covariances into account.

The criteria against which the significance of a current period ID should be evaluated can be

established by at least two different methods:

(1) The licensee could construct control chart limits using current and historical material 

balance closure data, where such limits for further action should be established at a level 

of significance of 0.01. The limits should be based on the statistical variance-covariance 

structure of the current ID and an appropriate sequence of previous IDs.

(2) The licensee could adopt three sigma control limits where sigma is determined as 

described in Chapter 9 of this document for the SEID.

In accordance with 10 CFR 74.59(f)(1)(i), the licensee must investigate excessive IDs. The 

following are actions that would be deemed appropriate as part of an investigation:

• If the ID > 3 times SEID and 300 grams U-235 (200 grams plutonium or U-233), then the 

licensee should take the following actions:

(1) Review inventory listing to ensure that all items and item quantities have been 

listed and none listed more than once.

(2) Review measurement results for previously unidentified biases.

(3) Review inventory documentation and book records for human errors and make 

appropriate corrections.

(4) Review inventory documentation and book records for anomalies, and 

investigate any anomalies to determine the need for remeasurements.

(5) Review holdup estimates for reasonableness relative to historical data.
NUREG-1280, Revision 2 94

(6) Calculate a standard deviation ( ) representative of relevant historical ID 

performance.

• If the ID < 3 times , no additional investigative actions are needed.

• If 5 FKG > ID > 3 :

(1) Compare material control test and item monitoring data with results of the 

physical inventory.

(2) Review results of trends analyses for all process units.

(3) Review conclusions of alarm investigations.

• If 10 FKG > ID > 3 and 5 FKG, then the licensee should take the following actions:

(1) Compare material control test and item monitoring data with results of the 

physical inventory.

(2) Review results of trends analyses for all process units.

(3) Review conclusions of alarm investigations.

(4) Review plant security records.

(5) Conduct next inventory within 2 months or as directed by the NRC.

• If the ID > 3 and > 10 FKG, then the licensee should take the following actions:

(1) Compare material control test and item monitoring data with results of the 

physical inventory.

(2) Review results of trends analyses for all process units.

(3) Review conclusions of alarm investigations.

(4) Review plant security records.

(5) Prepare facility for an immediate re-inventory.

(6) Remeasure a statistically determined sample of the items on hand at ending 

inventory for the material balance period in question that is sufficient to detect, 

with a 99-percent probability, at least one defective item if an actual loss of 

5 FKG or more from the ending inventory quantity occurred. A defective item is 

one that has had some or all of its SNM/SSNM contents removed, and the 

quantity removed exceeds three times the combined standard error of 

measurement (when taking into account the measurement uncertainties of both 

the original measurement and the remeasurement.
95 NUREG-1280, Revision 2

(7) For shipments (other than waste) made during the period, contact the 

appropriate receivers and request shipper-receiver evaluation data. For those 

shipments not yet measured by the receiver, request immediate measurement 

and resulting shipper-receiver evaluation data. Review all shipper-receiver data 

for the period for possible biases, measurement errors, and loss indications.

The results of all physical inventories and of investigations and resolution actions following any 

excessive ID are recorded and auditable. 

The licensee should describe any additional measures to be taken whenever a finalized ID 

(after applying any appropriate bias corrections and prior period adjustments) exceeds both 

three times the SEID and 200 grams of plutonium or U-233, or 300 grams of U-235 contained in 

highly enriched uranium, and the ID is not resolved within the reconciliation period of 

45 calendar days. For example, the additional measures could include halting all SNM/SSNM 

processing. (Note: This applies to both positive and negative ID values.)

The concept of active inventory is adequately described and represents the quantity of material 

typically handled under normal plant operating conditions.

 

97 NUREG-1280, Revision 2

11. SHIPMENTS AND RECEIPTS

11.0 Regulatory Intent

The intent of the 10 CFR 74.59(h)(1) shipments and receipts requirement is to ensure accurate 

identification and measurement of the quantities of SNM/SSNM shipped and received and to 

promptly detect and resolve all significant shipper-receiver differences. Timely and accurate 

quantification of the SNM/SSNM content of shipments and receipts is an essential component of 

an effective MC&A system. Shipper-receiver comparisons, on both an individual batch basis 

and on a total shipment basis, are important for confirming that either the shippers’ and 

receivers’ values are acceptable for establishing the book accounting quantities associated with 

received material or detecting unacceptable shippers’ or receivers’ values.

11.1 Receiving Procedure

The first action to be taken upon receipt of SNM/SSNM should be the verification of the number 

of items, the item identities, and the integrity of individual items and the TIDs. In addition, 

SNM/SSNM receipts should be measured for total quantity (mass), element concentration (such 

as for PuO2, UO2, or uranyl nitrate solutions), and fissile isotope abundance (U-235 or U-233). 

The validity of the shipper’s data should be substantiated with appropriate and timely receiver 

checks and measurements, including gross weight, adequate sampling techniques, NDA 

measurements (if appropriate), and destructive measurements (scrap excepted).

The MC&A plan should describe how materials are received, stored, and measured. The latter 

should include a description of the sampling techniques employed.

For any SNM/SSNM received, the licensee must provide all appropriate information on the 

DOE/NRC Form 741 that accompanies the shipment, in accordance with 10 CFR 74.15, 

“Nuclear Material Transaction Reports.” (Note: See NUREG/BR-0006, “Instructions for 

Completing Nuclear Material Transaction Reports (DOE/NRC Forms 741 and 740M) for 

instructions and requirements for completing DOE/NRC Form 741.)

11.2 Evaluation of Shipper-Receiver Differences

When shipper’s measurement uncertainty (or standard error) information is available, the 

following equation should define the combined measurement standard error:

combined standard error = [(σS)

2 + (σR)2

] 1/2

where

σS = shipper’s measurement standard error

σR = receiver’s measurement standard error

If the shipper's measurement uncertainty values are not available, the receiver can assume that 

the shipper’s measurement uncertainty is equal to (but no greater than) its own uncertainty. In 
NUREG-1280, Revision 2 98

this situation (i.e., both shipper and receiver have the same measurement uncertainty), the 

following equation reflects the combined measurement standard error:

combined standard error = [ 2 (σR)

2

] 1/2

= 1.414 σR

The difference between the shipper’s value and the receiver’s value, in terms of the total 

shipment, must be regarded as significant whenever the shipper-receiver difference exceeds 

twice the combined standard error and the larger of 0.5 percent of the amount of SNM/SSNM in 

the container, lot, or shipment or 50 grams of SSNM. 

The MC&A plan should describe the method for evaluating shipper-receiver differences and 

investigating these differences if they are significant. The description should include the 

following:

• the method of establishing the standard deviation of the shipper-receiver difference 

estimator under conditions when the shipper’s uncertainty estimate is available and 

when it is unavailable

• the conditions under which a referee laboratory is involved and the criteria for selecting a 

referee laboratory

• the bases established for concluding that a significant difference is resolved

• the procedure for adjusting book records to accommodate resolution of the difference

• the procedure for establishing and resolving differences involving scrap

11.3 Shipping Procedure

The MC&A plan should describe the preparation and certification procedures for shipping 

SNM/SSNM. The description should include the following:

• the measurement data and tamper-safing information provided to the group responsible 

for SNM/SSNM shipments

• the cross-checks, including any item checks or measurements, made by the shipping 

group

• the types of records maintained by the shipping group

11.4 Commitments and Acceptance Criteria

In its MC&A plan, the licensee should provide definitive commitments that adhere to the 

regulatory requirements and meet the acceptance criteria applicable to shipments and receipts. 

A finding that the licensee’s MC&A plan for processing shipments and receipts is acceptable 

and in accordance with 10 CFR 74.59(h)(1) will be based on, but not limited to, the following 

acceptance criteria:

• Receipts are inspected promptly to verify the validity of the shipper's data. The following 
99 NUREG-1280, Revision 2

times are acceptable for completing the verification measures:

− item verification—24 hours

− seal integrity—24 hours

− gross weight—72 hours

− NDA measurements (if appropriate)—120 hours

− destructive measurements (scrap excepted)—30 days

• Times other than those indicated above would be acceptable with adequate justification.

• Shipper’s values may be accepted and booked without receiver verification 

measurements for encapsulated items (e.g., fuel rods and elements), if an NDA 

measurement is not feasible. However, an exemption from 10 CFR 74.59(d)(1) would 

be necessary.

• The investigation of statistically significant shipper-receiver differences should normally 

be completed within 3 months except when the difference exceeds 5 FKG. In the latter 

case, the discrepancy should be resolved within 30 days of the time that its existence is 

determined.

• The NRC is to be notified of any inability to resolve any statistically significant 

shipper-receiver difference that exceeds the larger of either 50 grams SSNM or 

0.50 percent of the SSNM quantity involved. Such notification is to be made within 

30 days following the receipt of the material for differences that equal or exceed 5 FKG 

and within 90 days for differences that are less than 5 FKG.

• The following stepwise analysis is an example of an acceptable approach for 

investigating a significant shipper-receiver difference:

− The receiver reviews its data to check for possible entry errors, such as an 

incorrect number or the transposition of numbers.

− The receiver then reviews source data, including the basic calculations and the 

associated measurement control data.

− Assuming the difference remains unresolved, the receiver remeasures the SSNM 

content of the receipt.

− If remeasurement fails to resolve the difference, the shipper is notified and 

requested to conduct a similar investigation.

− If the two parties fail to resolve the difference, a referee laboratory should be 

involved. The shipper and receiver should mutually agree on the sampling 

procedure.
NUREG-1280, Revision 2 100

− Unless contractual requirements dictate otherwise, the value closest to the 

referee's value is accepted and booked by both parties. If the referee’s value is 

not within statistical limits of either the shipper or receiver, but lies between the 

two, the referee’s value is used.

• For purposes of shipper-receiver evaluation, a “lot” may be defined in several ways, 

including the following:

− multiple containers of a material that has been blended by a procedure that has 

been demonstrated to produce a homogeneous product

− multiple containers filled from a master container of homogeneous material (e.g., 

UF6 cylinders)

− a quantity of scrap transferred on multiple transfer receipts (DOE/NRC Form 741) 

but combined for processing through recovery

• The documentation of shipments and receipts should be completed and transmitted 

within the time specified in NUREG/BR-0006.

• Only acceptable tamper-safing methods will be used, as described in Chapter 15 of this 

document and as agreed to with the receiver.

• Results of shipper-receiver difference investigations, including corrective actions, are 

documented and retained for at least 3 years.

• The element and isotopic content of SSNM shipped by the licensee are based on 

measurements obtained from measurement systems subject to the measurement control 

system.
101 NUREG-1280, Revision 2

12. SCRAP CONTROL

12.0 Regulatory Intent

The intent of the 10 CFR 74.59(h)(2) scrap control requirements is to ensure that the regular 

processing of scrap with relatively large measurement uncertainties precludes such scrap being 

the source of a problem at the time of physical inventories. Inaccurate scrap measurements 

could cause an apparent ID or conceal a theft or diversion. Segregation of internally generated 

scrap from that received from off site until accountability is established ensures that potential 

anomalies in assigned values will be attributed to the appropriate facility. The licensee must 

establish a scrap control system that ensures that internally generated scrap is segregated from 

scrap from other licensees or contractors until accountability is established. The scrap control 

system should ensure that any scrap with a measurement standard deviation greater than

5 percent of the measured amount is recovered so that the results are segregated by inventory 

period and recovered within 6 months of the end of the inventory period in which the scrap was 

generated, except where it can be demonstrated that the scrap measurement uncertainty will 

not cause noncompliance with 10 CFR 74.59(e)(5).

12.1 Location

The MC&A plan should identify the scrap and waste quantities of contained SSNM with respect 

to source, storage, and disposition. The licensee may refer to process flow charts and plant 

operations descriptions included in the annex to the plan.

12.2 Processing

The MC&A plan should describe the system for in-house processing of scrap, including 

recovery plant capacity, rate of recovery, and the estimated amount of scrap expected to be on 

hand at any given time. The plan should also describe any plans for shipments and for offsite 

recovery of scrap, as well as procedures for the control and discard of wastes containing SSNM, 

including procedures and capabilities for storage before discard.

12.3 Measurements

The MC&A plan should describe the procedures for determining the SSNM content of scrap and 

waste, including the criteria and procedures for segregation, identification, and classification of 

various kinds of scrap to facilitate measurement. The plan should identify the types and 

quantities of scrap expected to have measurement uncertainties greater than plus or minus

5 percent (1σ).

12.4 Inventory Control

The MC&A plan should describe scrap control measures that will be implemented to ensure that 

scrap measured with a measurement standard deviation greater than plus or minus 5 percent

does not remain on inventory longer than 6 months beyond the inventory period in which it was 

generated or that the measurement uncertainty associated with the scrap on hand will not cause 

noncompliance with 10 CFR 74.59(e)(5).
NUREG-1280, Revision 2 102

12.5 Recovery of Offsite Scrap

The MC&A plan should describe procedures that the licensee will implement to ensure that 

scrap received for recovery from off site is segregated until accountability is established. The

description should address segregation during storage and processing.

12.6 Commitments and Acceptance Criteria

In its MC&A plan, the licensee should provide definitive commitments that adhere to the 

regulatory requirements and meet acceptance criteria applicable to scrap control. A finding that 

the licensee’s MC&A plan for processing scrap is acceptable and in accordance with 

10 CFR 74.59(h)(2) will be based on, but not limited to, the following acceptance criteria:

• Storage locations for scrap and waste are identified. Scrap and waste generation rates 

are estimated for each process unit. Methods for disposition of waste are described.

• A comparison of generation rates and recovery capacity indicates that adequate 

recovery capability exists to preclude the buildup of excess amounts of scrap.

• Special handling procedures for waste, such as conversion to a better measurable form 

or independent measurement verification, are described.

• Proposed measurement techniques for specific scrap types are described, including the 

following where appropriate:

– material description

– specific NDA system to be employed

– container size

– mixing and blending operations

– sampling technique

– assay procedure

• An estimate of the measurement uncertainties associated with each scrap type is 

included in the annex to the MC&A plan.

• For those materials measured by NDA in 30-gallon drums or larger containers, the 

licensee should commit to an annual evaluation to demonstrate the continuing reliability 

of the measurement system. Possible evaluation techniques include a destructive 

analysis of a previously NDA-measured 30-gallon drum, a second NDA technique not 

subject to the same potential interferences as the primary technique, or a standard 

addition procedure.
103 NUREG-1280, Revision 2

• The program segregating scrap generated off site from onsite scrap should be adequate 

to protect against commingling. Possible techniques to achieve this objective include 

the following:

– Retain customer scrap in shipping containers before recovery.

– Isolate customer scrap in a particular section of a vault or permanently CAA.

– Identify designated storage bins or shelves for application of limited access 

controls.

• Where offsite recovery is utilized, the description of the program should include, at a 

minimum, the following information:

– types and estimated quantities of scrap to be shipped

– contractor’s program to ensure segregation of customer scrap

– basis for establishing accountability values

– contractor and shipper measurement responsibilities

– means of performing shipper-receiver comparisons

• Segregation of customer scrap during processing is accomplished by cleaning the 

dissolver and accountability weigh tank before and after the recovery campaign. 

Additional processing of dissolver residues should be handled in the same manner,

unless the quantity involved is less than 1 FKG or the measurement uncertainty is less 

than plus or minus 5 percent at the one sigma level.

• Scrap and waste will only be stored in approved locations and disposal of by approved 

methods.

• Adequate onsite recovery capacity and adequate provision for offsite recovery exist to 

ensure compliance with the requirements of 10 CFR 74.59(e)(5).

• Listed quantities of scrap and waste present during a physical inventory will be derived 

from measurements when possible. Otherwise, such SSNM quantities will be based on 

average historical factors, which in turn are derived from measurements performed on 

each type of scrap and waste in question.

• Methods used to measure scrap and waste are subject to the measurement control 

program described in Chapter 8 of this document.

• Scrap control procedures are in place that provide for (1) segregation of offsite scrap 

receipts from one another and from onsite-generated scrap until accountability and 

shipper-receiver differences have been established and (2) segregation of 

onsite-generated scrap by plant (when a licensee has more than one onsite plant) until 

after dissolution plus residue measurements are obtained.

105 NUREG-1280, Revision 2

13. ASSESSMENT AND REVIEW OF THE MATERIAL CONTROL 

AND ACCOUNTING PROGRAM

13.0 Regulatory Intent

The intent of the 10 CFR 74.59(h)(4) assessment requirements is for the licensee to 

independently assess the MC&A program. It is intended that the review will be performed by 

knowledgeable, technically competent individuals free from conflicts of interest and that the 

deficiencies will be brought to the attention of plant management so that they will be corrected. 

It should be emphasized that this review process is intended to be much more than a routine 

audit for compliance with existing procedures and commitments. Conclusions and 

recommendations relative to overall program effectiveness and to the adequacy of the program,

including that of any contractor who performs SNM/SSNM measurements as part of the 

licensee’s MC&A program, to meet and satisfy regulatory intent should be made.

As required by 10 CFR 74.59(h)(4), licensees must perform independent assessments every 

12 months to evaluate the performance of the MC&A system, review its effectiveness, and 

document management’s action on prior assessment recommendations. Assessments must 

include an evaluation of the measurement control program of any outside contractor laboratory 

performing MC&A measurements for a licensee, unless the contractor is also subject to the 

requirements of 10 CFR 74.59(e).

13.1 General Description

The licensee should independently review and assess the capabilities, performance, and overall 

effectiveness of its MC&A program at least every 12 months. The MC&A plan should describe 

the assessment and review program in terms of the following:

• maximum interval between assessments

• selection procedures for the assessment team

• number of team members to be selected

• qualification and expertise of team members

• independence of individual team members from the MC&A responsibilities and activities 

they are reviewing and assessing

• maximum elapsed time and minimum actual effort to be used for completion of the 

assessment and issuance of a final team report

Generally, the entire MC&A program should be reviewed and evaluated during each 

assessment. When this occurs, intervals between assessments can be as much as 12 calendar 

months. However, if individual assessments only cover part of the MC&A system, individual 

subsystems should be assessed at intervals no greater than 6 calendar months. Thus, the type 

of assessment (partial or total) and the maximum interval between assessments should be 

specified. “Interval” means the elapsed time between either the start of or termination of 

successive assessments.
NUREG-1280, Revision 2 106

The responsibility and authority for the assessment program should be at least one level higher

in the licensee’s organizational structure than that of the MC&A manager. Such responsibility 

should include selecting the assessment team leader and initiating corrective actions. Team 

members may be selected from the facility staff or from outside, but an individual member 

should not participate in the assessment of the parts of the MC&A system for which he or she

has direct responsibility. Hence, the MC&A manager may not be a team member. Also, a given 

individual should not assess the parts of the system that are the responsibility of another team 

member if the other team member is assessing the given individual’s area. The leader of the 

assessment team should have no responsibilities for managing any of the MC&A elements 

being assessed.

The actual number for any given assessment should depend on the knowledge and expertise of 

the team relative to MC&A activities and their experience in conducting assessments. 

Personnel assigned to the assessment team should have demonstrated an understanding of the 

regulatory objectives and requirements of the MC&A program and should have sufficient 

knowledge and experience to be able to judge the adequacy of the parts of the system they 

review. The team should have authority to investigate all aspects of the MC&A system and 

should be given access to all necessary information.

To provide a meaningful and timely assessment, the review and evaluation process should not 

be protracted. The actual review and investigation activities should be completed in 30 calendar 

days, with an additional 15 calendar days allowed for completing and issuing a final team report.

13.2 Report of Findings and Recommendations

The areas to be reviewed should encompass the entire MC&A system, and the level of detail of 

the reviews should be sufficient to ensure that the assessment team has made an adequate and 

reasoned judgment of the MC&A system effectiveness. The team report, at a minimum, should 

state findings pertaining to the following:

• organizational effectiveness to manage and execute MC&A activities

• management responsiveness to indications of possible losses of uranium

• staff training and competency to carry out MC&A functions

• reliability and accuracy of accountability measurements made on SNM/SSNM

• effectiveness of the measurement control system in monitoring measurement systems 

and its sufficiency to meet the requirements for controlling and estimating both bias and 

SEID

• soundness of the material accounting records

• effectiveness of the process monitoring system in monitoring the status of material in

process and detecting abrupt loss of SSNM

• effectiveness of the item monitoring system in tracking and providing current knowledge 

of items
107 NUREG-1280, Revision 2

• effectiveness of alarm resolution

• capability to promptly locate items and effectiveness in doing so

• timeliness and effectiveness of shipper-receiver difference evaluations and resolution of 

excessive shipper-receiver differences

• soundness and effectiveness of the inventory-taking procedures

• capability to confirm the presence of SNM/SSNM

• capability to detect and resolve indications of missing SNM/SSNM

On completion of each assessment, the findings and recommendations for corrective action, if 

any, should be documented. The written report should be distributed to the plant manager, the 

MC&A manager, and other managers affected by the assessment.

13.3 Management Review and Response to Report Findings and Recommendations

Management should review the assessment report and take the necessary actions to correct 

MC&A system deficiencies. The management review should be documented within 30 days 

following the submittal of the assessment team’s report, and it should include a schedule for the 

correction of deficiencies. Corrective actions, if any, that pertain to daily or weekly activities 

should be initiated promptly after the submittal of the final assessment report.

The MC&A plan should address resolution and followup actions associated with concerns 

identified in the assessment report. The plan should specify the individuals responsible for 

resolving identified concerns and the timeliness of such resolution.

13.4 Commitments and Acceptance Criteria

In its MC&A plan, the licensee should provide definitive commitments that adhere to the 

regulatory requirements and meet acceptance criteria applicable to the independent 

assessment of the MC&A program. A finding that the licensee’s MC&A plan for independently 

assessing the effectiveness of the MC&A program is acceptable and in accordance with 

10 CFR 74.59(h)(4) will be based on, but not limited to, the following acceptance criteria:

• Independent assessments of the total MC&A system are performed at intervals not to 

exceed 12 calendar months and assess the performance of the system, review its 

effectiveness, and document management’s action on prior assessment 

recommendations and identified deficiencies. Such assessments must include a review 

and evaluation of any contractor who performs SNM accountability measurements for 

the licensee, in accordance with 10 CFR 74.59(h)(4).

• The periodic assessments will be comprehensive and sufficiently detailed to enable the 

assessment team to rate the MC&A system accordingly. The overall assessment 

objectives are to determine whether the MC&A system, as designed and implemented, 

is continuing to meet the general performance objectives and to identify weaknesses or 

deficiencies in the system design or performance that may need correcting.
NUREG-1280, Revision 2 108

• The areas to be reviewed encompass the entire MC&A program and the level of detail of 

the reviews is sufficient to ensure that the assessment team has adequate information to 

make reasoned judgments of the MC&A system effectiveness. The following areas 

should be evaluated:

− organizational effectiveness and management responsiveness to indicators of 

possible SNM/SSNM losses

− effectiveness of the process monitoring, item monitoring, and alarm resolution 

programs to detect any abrupt SSNM loss in a timely manner

− staff training and competency to carry out MC&A functions

− soundness of the material accounting records

− capability to promptly locate items

− timeliness and effectiveness of shipper-receiver difference evaluations and 

resolution of significant shipper-receiver differences

− soundness of physical inventory procedures and practices

− effectiveness of the measurement control system to monitor key measurement 

systems, establish bias estimates and measurement uncertainties, and meet the 

requirements for controlling the total MC&A measurement uncertainty associated 

with ID, in accordance with 10 CFR 74.59(e) and 10 CFR 74.59(f)

− capability to confirm the presence of SNM/SSNM

− capability to investigate and resolve anomalies and aid in any Government-led 

investigation pertaining to missing SNM/SSNM and to provide information that 

would aid in the recovery of missing SNM/SSNM

• Generally accepted auditing principles are used to check each type of record in which a 

representative sample (of a sufficient number) of randomly selected records is 

examined.

• Personnel assigned to the assessment team have an adequate understanding of the 

regulatory objectives and requirements of the MC&A system and have sufficient 

knowledge and experience to be able to judge the adequacy of the parts of the system 

they are asked to review. The team has authority to investigate any aspect of the MC&A 

program and has access to all relevant information.

• An individual team member will not participate in the assessment of any part of the 

MC&A system for which he or she has direct responsibility. Also, an individual “A” will 

not assess any part of the system that is the responsibility of person “B,” if person “B” is 

assessing an area under the responsibility of individual “A.”

• The entire MC&A system will be reviewed and evaluated during each single assessment 

(to be completed within an elapsed time that is short relative to the time between 
109 NUREG-1280, Revision 2

changes in the MC&A system and is demonstrated to be able to include any such 

changes made during the review and assessment). Conducting two or more 

assessments during a 12-month interval, in which only part of the MC&A system is 

covered in each, is not deemed acceptable. That is, reviewing a single component of 

the MC&A program at 12-month intervals is not meaningful unless knowledge is 

obtained of how well the other components currently interact. Piecemeal review and 

evaluation is permissible, however, if each subsystem is covered at 6-month (or less) 

intervals.

• The leader of the assessment team will have no responsibilities for performing or 

managing the functions being assessed.

• The responsibility and authority for the assessment program and for initiating corrective 

actions should be (1) at least one level higher in the organization than the MC&A 

manager or (2) at a level equal to that of the onsite plant manager.

• Reviews and assessments are performed either by qualified individuals from outside or 

qualified individuals from inside the facility organization whose work assignments and 

positions within the organization will not impair their ability to make objective judgments 

of the MC&A program capabilities and performance.

• Each overall review and assessment will be conducted and completed in a timeframe 

that is short with respect to the time for changes to have occurred in the MC&A program 

and will include any such changes made during the time the review and assessment is 

being conducted.

• The completion date for any review and assessment is defined as the date when the 

team submits its final written report (of findings and recommendations) to plant 

management. The start date is the first day in which one or more team members 

actually inspect records or interview MC&A personnel. Such start date will be 

documented.

• The results of the assessment and recommendations for corrective action, if any, will be 

documented and reported to the plant manager and other managers affected by the 

assessment. Management will review the assessment report and take the necessary 

actions to correct MC&A program or system deficiencies. Such corrective actions (if 

any) that pertain to daily or weekly activities will be initiated within 40 calendar days 

following the submittal of the review and assessment final report.

• Management’s response to recommendations from the review and assessment, 

including any corrective actions ordered by management and the expected timeframe for 

completing such actions, will be documented within 30 calendar days following the 

submittal of the team’s report.

111 NUREG-1280, Revision 2

14. DESIGNATION OF MATERIAL BALANCE AREAS, 

ITEM CONTROL AREAS, AND CUSTODIANS

14.0 Regulatory Intent

The intent of the requirement to designate MBAs, ICAs, and assign custodial responsibilities in 

10 CFR 74.59(h)(5) is to ensure that licensees establish various material control boundaries to 

minimize the occurrence of, and facilitate resolution of, MC&A anomalies, such as IDs, missing 

items or nuclear material, and potential theft or diversion of nuclear materials. The intent is also

to ensure that there is a designated individual who is responsible for having knowledge of the 

placement and movement of SNM/SSNM within a specified area and transfers into and out of 

the area. Such an individual should be vested with the authority to obtain the information 

necessary to accomplish his or her task and to ensure that activities are carried out in 

accordance with approved policies and procedures.

As required by 10 CFR 74.59(h)(5), a licensee must designate MBAs and ICAs and assign 

custodial responsibility for each of these areas in a manner that ensures that such responsibility 

can be effectively executed for all SNM/SSNM possessed under license.

14.1 Material Control Boundaries

The MC&A plan should describe how the licensee establishes various material control 

boundaries to minimize the occurrence of, and facilitate resolution of, MC&A anomalies. 

Examples of such anomalies are IDs, missing items of SNM/SSNM, and potential theft or 

diversion of SNM/SSNM.

Because MBAs and ICAs are important foundations for controlling and accounting for all 

SNM/SSNM in a facility, the MC&A plan should describe the process for how their locations are 

chosen. An MBA or ICA should correlate to physical or administrative boundaries and 

monitored locations. The MBA or ICA should be designed to limit losses to a specific area (i.e., 

the MBA should not be so large that it cannot localize inventory or process differences to a 

manageable level). Materials transferred into and out of an MBA or ICA must have quantitative 

measurements, as specified in the definitions of MBAs and ICAs in 10 CFR 74.4.

The MC&A plan should identify the areas into which the facility will be divided to ensure that 

custodianship can be effectively executed. Clarification can be provided by reference to facility 

drawings included in the annex to the MC&A plan.

14.2 Custodians

The MC&A plan should describe the roles and responsibilities of the custodians for MBAs and 

ICAs. Each custodian should have direct interaction with the MC&A organization, and such 

individuals should be located within the physical operations area. Custodians who are 

responsible for more than one MBA or ICA should not have the authority to make material 

transfers between MBAs or ICAs which are under their direct control.

14.3 Commitments and Acceptance Criteria

In its MC&A plan, the licensee should provide definitive commitments that adhere to the 

regulatory requirements and meet acceptance criteria applicable to designation of MBAs, ICAs, 
NUREG-1280, Revision 2 112

and custodians. A finding that the licensee’s MC&A plan for designation of MBAs, ICAs, and 

custodians is acceptable and in accordance with 10 CFR 74.59(h)(5) will be based on, but not 

limited to, the following acceptance criteria:

• MBAs and ICAs should have a defined physical or administratively controlled area which 

allows for the physical and administrative control of nuclear materials such that the 

quantity of nuclear materials being moved into or out of the MBA is a 

measurement-based assigned value for element and isotope contents.

• Except for the stipulations that all SNM/SSNM crossing custodial area boundaries must 

be measured in accordance with 10 CFR 74.4 and that custodians must be able to 

effectively execute their duties, there are no restrictions on how large an area can be. 

However, different MAAs should have different custodians, and within an MAA, areas 

with widely divergent functions should have different custodians. An example of the 

latter situation would be a fabrication plant in which bulk material is handled in one area 

in the preparation of the fuel component of an element, and a second area is involved 

with machining and preparation of the element for higher tier fabrication.

• A current listing of designated custodians and alternates should be maintained.

• Custodians should be familiar with SNM/SSNM processing activities as well as MC&A 

functions. A minimum of 1 year of experience in each of these areas is desirable.

• Custodians should not be production or process operations personnel so as to preclude 

the possibility of conflicts of interest.

• MBAs and ICAs are established in such a way as to minimize the occurrence of, and 

facilitate the resolution of, MC&A anomalies.

• MBA and ICA structures are properly documented and clearly described, including 

physical boundaries and categories of material in the individual MBA or ICA. 

• Custodial responsibilities are assigned for each designated MBA and ICA.

• Custodians responsible for more than one MBA or ICA are not authorized to transfer 

material between MBAs and ICAs under their control to prevent misuse.

• The SNM/SSNM processing facility is subdivided into a sufficient number of areas to 

ensure that custodial responsibilities can be effectively executed.

• A custodian and a minimum number of alternates are designated for each area 

subdivision.
113 NUREG-1280, Revision 2

15. TAMPER-SAFING

15.0 Regulatory Intent

The intent of the 10 CFR 74.59(f)(2)(i) tamper-safing provision is to require the establishment, 

maintenance, and protection of a tamper-safing program that will demonstrate that the licensee 

maintains and follows procedures for tamper-safing of containers or vaults containing

SNM/SSNM or utilized for ensuring the validity of prior measurements. The program should 

include control of access to, and distribution of, unused seals and records which document the 

distribution, application, and destruction of tamper-safing devices, as well as routine inventory of 

unused tamper-safing devices. Records are to be retained for at least 3 years (or longer if 

specifically required by regulations external to 10 CFR 74.51), thereby providing a means for 

assessing the performance of the tamper-safing program and inspecting for compliance with 

regulatory requirements.

15.1 Characteristics of Tamper-Safing Devices

Tamper-safing devices on containers or vaults is one level of protection used to secure the 

integrity of SNM/SSNM either when it is in transit or stored on site. The one overriding objective 

of TIDs is to ensure that no tampering or entry has occurred while the TID is on the container. 

Therefore, for MC&A purposes, the degree of confidence in the selection of a TID sealing 

system will vary depending on its unique characteristics and intended use.

When selecting tamper-safing devices, licensees should consider the following:

• Intended use—the determination the tamper-safing device is appropriate for the 

tamper-safing of the container and withstanding the working environment (i.e., 

temperature, moisture, repeated handling, dirt)

• Application—the relative ease or difficulty of physically applying the tamper-safing device

• Substitution—the ability of a tamper-safing device to be destructively removed and 

replaced by new seals without detection

• Removal and reapplication—the ability of a tamper-safing device to be removed and 

reapplied without detection

• Alteration of label data—the ability to alter recorded data on the tamper-safing device 

without the alteration being apparent

• Integrity verification—the degree of effort required to verify that the tamper-safing device 

is intact or indicates tampering

The licensee should confirm a manufacturer’s claims that the removal of the seal is not possible 

without detection by testing potential tamper-safing devices to see whether they can be 

removed from the containers on which they are to be used. The licensee should confirm the 

results by following the manufacturer’s documented procedures and the samples used. The 

experiments should be documented, both with regard to what techniques were used to attempt 

to defeat the tamper-safing device and observations as to the degree of success in defeating 
NUREG-1280, Revision 2 114

the tamper-safing device. In lieu of testing by the licensee, similar tests conducted by an 

independent third party may be considered acceptable.

15.2 Use of Tamper-Safing Devices

The MC&A plan may allow the use of tamper-safing devices to do the following:

• Ensure the long-term validity of measurement data. The application of a tamper-safing 

device to an item containing measured quantities of nuclear materials may allow the 

licensee to maintain the validity of the original measured value, thus eliminating or

decreasing the frequency of the need to remeasure the items to verify its nuclear 

material content.

• Reduce the effort to conduct physical inventories or item control activities. The 

application of a tamper-safing device to a container housing multiple items may allow the 

licensee to maintain the validity of container’s contents, thus minimizing the number of 

items required to be verified during a physical inventory or item control activity.

• Provide assurance of integrity of in-transit material. The application of a tamper-safing 

device to a shipping container may allow the licensee to maintain the validity of the

shipping container’s contents and provide assurance that the integrity of the shipment 

has not been violated. To achieve this goal, the shipper should apply the tamper-safing 

device to the shipping container, verify the integrity of the tamper-safing device shortly 

before departure of the shipment, and provide the appropriate information (i.e., shipping 

container serial numbers, tamper-safing device type, and serial number) to the receiver. 

Upon receipt of the shipment, the receiver should verify the shipping container serial 

numbers, tamper-safing device type, serial number, and tamper-safing device integrity. 

Any discrepancies should be considered an MC&A anomaly and be addressed by the 

facility’s MC&A resolution program.

15.3 Description of Tamper-Safing Records

The tamper-safing system should identify all records, forms, reports, and standard operating 

procedures used throughout the system. Such records should include, but are not limited to, 

the following:

• receipt of purchased TIDs

• issuance of TIDs

• identification of the person applying the TIDs

• identification of the person who is verifying the application of the TID

• identification of the container to which the TID was applied, including the TID serial 

identification (if applicable)

• removal and destruction of TIDs
115 NUREG-1280, Revision 2

• routine inventory of unused and unissued TIDs

• identification of roles and responsibilities, including the following:

− designation of the TID control officer 

− personnel approved to apply, verify, and destroy TIDs

• training of personnel in the application, verification, and destruction of TIDs

15.4 Commitments and Acceptance Criteria

The acceptability of a TID is based on an evaluation of the attributes of the device in relation to 

time to defeat the tamper-indicating features. The NRC has already deemed the following TIDs

acceptable: Type E, pressure-sensitive, tamper-evident wire seals, fiber optic seals, and steel 

padlocks. Other tamper-safing devices may be equally acceptable. Licensees proposing to use 

TIDs not currently approved by the NRC must provide the appropriate information, including 

references, to enable licensing reviewers to assess the adequacy of the proposed TID type.

In its MC&A plan, the licensee should provide definitive commitments that adhere to the 

regulatory requirements and meet the acceptance criteria applicable to the use of TIDs. A 

finding that the licensee’s MC&A plan for tamper-safing is acceptable and in accordance with 

10 CFR 74.59(f)(2)(i) will be based on, but not limited to, the following acceptance criteria:

• Unissued TIDs are stored in a locked container within a room that is locked when 

unoccupied or in an approved repository.

• Blocks of TIDs issued to designated individuals are stored in a locked container within a 

room that is locked when unoccupied or in an approved repository.

• Preferably a single individual, but no more than three individuals, none of whom have 

any responsibility for seal application or destruction, is designated as the TID control 

officer.

• When TIDs are not in storage they are in the possession of authorized individuals (i.e., 

the TID control officer or person responsible for applying the TID). The number of 

available TIDs issued to these individuals should be limited to a single day’s use.

• The licensee has in its possession a commitment from the seal manufacturer that plates 

or dies, or both, and production residuals are controlled and protected.

• Upon removal, TIDs are destroyed (i.e., crimped, flattened, or otherwise rendered 

unusable) and properly disposed.

• Only TIDs that are controlled and accounted for are used to maintain the validity of 

previously established SNM/SSNM quantities associated with items.

• TIDs are only applied and removed by individuals authorized for that purpose.
NUREG-1280, Revision 2 116

• Unused TIDs are controlled and inventoried.

• Written procedures are maintained to ensure that individuals authorized to handle TIDs

are properly trained.

• Records of TID application, verification, removal, and destruction are documented, and 

control measures are implemented to prevent alteration of records concerning 

containers protected by TIDs.
117 NUREG-1280, Revision 2

16. RESOLVING INDICATIONS OF LOSS, THEFT, DIVERSION,

OR MISUSE OF SPECIAL NUCLEAR MATERIAL AND 

STRATEGIC SPECIAL NUCLEAR MATERIAL

16.0 Regulatory Intent

The intent of the 10 CFR 74.3(b) and 10 CFR 74.3(c) general performance objectives is that 

licensees be able to promptly investigate and resolve any indications of a possible loss, theft, 

diversion, or misuse of SNM/SSNM whether arising from errors or deliberate actions.

16.1 Methods and Procedures for Identifying Indicators

The MC&A plan should discuss the means by which the licensee will resolve indicators of a 

possible loss, theft, diversion, or misuse of SNM/SSNM. The licensee’s resolution program 

should address the possible indicators of missing material. The MC&A plan should enumerate 

all potential indicators that can be postulated and develop resolution procedures for each. Any 

anomaly could potentially be an indicator of loss, theft, diversion, or misuse of SNM/SSNM. An 

anomaly is an unusual observable condition (such as excessive discrepancies, missing items, 

broken TIDs, or other possible indicators) which might result from the theft, diversion, or other 

misuse of SNM/SSNM. The terms “indicator” and “anomaly” may be used interchangeably to 

describe a condition that may require further investigation to determine whether an actual loss, 

theft, diversion, or misuse of SNM/SSNM occurred. 

The following are examples of possible indicators of missing SNM/SSNM:

• lack of agreement between a physical inventory and its associated book inventory in 

which the ID is positive and exceeds three times the SEID and more than 300 grams of 

U-235 or 200 grams of plutonium or U-233

• determination through the item control system that one or more items are not in their 

designated locations and the actual locations are not immediately known

• discovery that an item’s integrity or its TID was compromised

• information from the process control system indicating potential loss of material from the 

process system

• an allegation of theft or diversion

16.2 System and Procedures for Investigating and Resolving Loss Indicators

One or more MC&A procedures should address the system and practices for investigating and 

resolving loss indicators. The licensee should have well-defined procedures for promptly 

investigating and resolving indications of possible missing SNM/SSNM and procedures for 

rapidly determining whether an actual loss of SNM/SSNM has occurred. These procedures

should include criteria for determining when an investigation of loss indicators can be 

concluded. 

Resolving a loss indicator means that the licensee has determined that loss, including possible 

diversion or theft, has not occurred and is not occurring. For each type of indicator, the licensee 
NUREG-1280, Revision 2 118

should develop detailed resolution procedures and should describe or outline them in the MC&A

plan.

Any investigation of an indication of a loss or theft should provide, whenever possible (1) an 

estimate of the quantity of SNM/SSNM involved, (2) the material type or physical form of the 

material, (3) the type of unauthorized activity or event detected, (4) the timeframe within which 

the loss or activity could have occurred, (5) the most probable cause, and (6) recommendations 

for precluding reoccurrence.

For indications that a loss or theft may have occurred, the resolution process should include 

(1) thoroughly checking the accountability records and source information, (2) locating the 

source of the problem, (3) isolating the exact reason for the problem within the area or 

processing unit, (4) determining the amounts of SNM/SSNM involved, and (5) making a 

determination that the indication is or is not resolved. The resolution procedures should be 

prepared so that no individual who could have been responsible for the potential loss would also 

be responsible for its resolution. If an investigation of an indicator results in a conclusion that 

the indication is true, such conclusion must be reported to the NRC within 1 hour of its 

determination, in accordance with 10 CFR 74.11. The MC&A plan should specify the time 

allowed for resolution. In general, a time not exceeding 72 hours should be adequate.

16.3 Response Actions for Unresolved Indicators

The MC&A plan should clearly define response actions to unresolved, and these response 

actions should be on a graded scale appropriate to the level of potential safeguards 

significance. The plan should also define the responsibility and authority for initiating and 

executing such escalating levels of response actions.

For indicators of missing SNM/SSNM, the level of safeguards concern is related to factors such 

as the following: 

• the potential quantity of SNM/SSNM involved

• the material attractiveness of the potential missing uranium or plutonium (in terms of 

fabricating a nuclear explosive device) relative to its type, enrichment, composition or 

form (e.g., U metal, U3O8, uranyl nitrate solution, UF6, scrap, or waste).

16.4 Documentation Requirements

The MC&A plan should identify all documentation requirements associated with the licensee's 

program for the reporting, investigation, and resolution of missing SNM/SSNM indicators. The 

plan should define the licensee’s review and approval requirements and custodial responsibility. 

At a minimum, documentation of the following should be included:

• investigation procedures

• resolution procedures

• reporting of indicator to MC&A management, including date and time the indicator was 

reported, name of individual who discovered the indicator, and description of indication
119 NUREG-1280, Revision 2

• investigation findings and conclusion, including resolution status, date issued, name and 

signature of principal investigator, and approval signature of MC&A manager

• reports made to the NRC for unresolved indicators and for indicators determined to be 

real, including date and time the report was made, method of communication, and name 

of the NRC individual contacted

Section 17.3 of this document describes additional types of information that may be necessary. 

16.5 Commitments and Acceptance Criteria

In its MC&A plan, the licensee should provide definitive commitments that adhere to the 

regulatory requirements and meet acceptance criteria applicable to investigating and resolving 

anomalies indicating possible misuse of SNM/SSNM. A finding that the licensee’s MC&A plan 

for resolving indications of loss, theft, diversion, or misuse of SNM/SSNM is acceptable and in 

accordance with 10 CFR 74.3(b) and 10 CFR 74.3(c) will be based on, but not limited to, the 

following acceptance criteria:

• Adequate commitments are provided to ensure a high probability that any indicator of 

missing SNM/SSNM will be (1) recognized as an indicator, (2) promptly investigated, 

and (3) resolved.

• A prompt investigation will be conducted by the licensee for all indications of possible 

loss, theft, diversion, or misuse of SNM/SSNM.

• A cause or probable cause that is based on objective evidence will be assigned to each 

indication of possible loss that is investigated by the licensee.

• Investigation and resolution procedures will provide for adequate overchecks to ensure 

that no individual who could have been responsible for a possible loss or theft of 

SNM/SSNM would be the sole or primary individual responsible for resolving the 

indicator.

• No investigation relative to an indication of a loss or theft of SNM/SSNM exceeding the 

current SQ shall be declared as completed but unresolved without first conducting a 

shutdown, cleanout inventory in which all unsealed SNM/SSNM is remeasured for 

element and isotope contents.

• The results of all investigations of alleged thefts, and any indications of a loss of 

SNM/SSNM which remains unresolved after 30 calendar days will be reported to the 

appropriate NRC MC&A licensing authority.

121 NUREG-1280, Revision 2

17. INFORMATIONAL AID FOR ASSISTING IN THE INVESTIGATION 

AND RECOVERY OF MISSING SPECIAL NUCLEAR

MATERIAL AND STRATEGIC SPECIAL

NUCLEAR MATERIAL

17.0 Regulatory Intent

The intent of the 10 CFR 74.3(d) general performance objective is for licensees to have ready 

and provide to investigators any information deemed relevant to the recovery of SNM/SSNM 

involved in a loss or theft. The burden is on the licensee to provide (without being asked to) all 

information that it recognizes as being relevant, as opposed to only providing information that 

the investigators are knowledgeable enough to request. This objective pertains to investigations 

and recovery operations, relating to actual (or highly suspected) instances of missing 

SNM/SSNM, which would be conducted by the NRC or other government agencies, such as the 

Federal Bureau of Investigations.

The 10 CFR 74.3(d) performance objective states that the licensee must be able to provide, in a 

timely manner, information to aid in the investigation and recovery of missing SNM/SSNM in the 

event of an actual loss, theft, diversion or misuse.

17.1 Types of Information

The following information may aid the investigation and recovery effort:

• data or observations that led the licensee to determine that a loss or theft of uranium or 

plutonium may have occurred

• data, observations, and assessments associated with attempts to resolve the indication 

of missing material

• the time period during which the material may have left the facility

• the path and means by which the material may have left the facility

17.2 Information Indicating Possible Losses of Special Nuclear Material/Strategic Special 

Nuclear Material

Information indicating that a loss of uranium or plutonium may have occurred can come from 

process or production yield data, physical inventory results, item control activities, and 

shipper-receiver comparisons. This information could include the following:

• material accountability data records and reports

• inventory records

• ID and propagation of error calculations

• inventory reconciliation reports
NUREG-1280, Revision 2 122

• indications of unrecorded or unauthorized removals of SNM/SSNM from storage or 

process locations

• reports of apparent destruction or falsification of records pertaining to SNM/SSNM

• records of broken TIDs or compromised item integrity

• indications of unauthorized entry into SNM/SSNM storage areas

• reports from monthly item status inspections

• material receipt and log-in records

• results from shipper-receiver difference evaluations

• process quality assurance or production control records

• documentation relating to an alleged or confirmed theft

17.3 Information on Resolving Indications of Missing Special Nuclear Material/Strategic 

Special Nuclear Material

Chapter 16 of this document provides information associated with resolving indications of 

missing SNM/SSNM. This information and information that may be of aid in the recovery of 

missing material could include the following:

• the type of unauthorized activity detected

• the interval during which the loss may have occurred

• the amount of material and form of the material involved in the loss

• results of measures to validate indicators

• results of extended measures to resolve indicators

• results from special inventories (or reinventories) and tests performed

• audit results of the SNM/SSNM accountability source data

• assessments of measurement data and measurement controls

• results from reviews of the MC&A program and status of corrective actions

• history of indicator investigation and resolution activities

• anomaly investigation and resolution procedures and conclusions

• probable cause of the loss
123 NUREG-1280, Revision 2

• any abnormal events that may have contributed to or caused the loss

• the names of individuals who could have been responsible for the loss

Much of the backup information necessary to assist in an investigation would be records 

maintained in the facility records system described in Chapter 18 of this document.

17.4 Commitments and Acceptance Criteria

In its MC&A plan, the licensee should provide definitive commitments that adhere to the 

regulatory requirements and meet acceptance criteria applicable to providing information for 

assisting in the investigation and recovery of missing SNM/SSNM. A finding that the licensee’s 

MC&A plan for providing informational aid is acceptable and in accordance with 10 CFR 74.3(d) 

will be based on, but not limited to, the following acceptance criteria:

• Procedures are in place for the efficient and timely gathering of relevant information to 

be provided to investigators to aid in the investigation and recovery activities associated 

with missing SNM/SSNM.

• Information will be provided to appropriate government authorities to aid in their 

investigation of indications or allegations of missing material and in the recovery of 

SNM/SSNM in the event of a loss that could include theft or diversion.

125 NUREG-1280, Revision 2

18. RECORDKEEPING

18.0 Regulatory Intent

The intent of the 10 CFR 74.59(g) recordkeeping requirements is to ensure that licensees

establish and maintain specific records that demonstrate that the general performance 

objectives of 10 CFR 74.3 and 10 CFR 74.51(a), as well as the program capabilities of 

10 CFR 74.51, 10 CFR 74.53, 10 CFR 74.55, 10 CFR 74.57, and 10 CFR 74.59 have been met. 

In accordance with 10 CFR 74.59(g), records must be retained for a minimum of 3 years (or 

longer if specifically required by 10 CFR Part 75, “Safeguards on Nuclear Material—

Implementation of US/IAEA Agreement”). Note that, in accordance with 10 CFR 74.19(b), 

MC&A procedures (as documented in licensee records) must be retained until the Commission 

terminates the license.

Records provide a means for assessing the performance of the MC&A program and inspecting 

for compliance with regulatory requirements. 

18.1 Description of Records

The MC&A plan should identify all records, forms, reports, and standard operating procedures 

that show compliance with the requirements of 10 CFR Part 74. Such records should include, 

but are not limited to, the following:

• documents that define changes in the MC&A management structure or changes in 

responsibilities relating to MC&A positions

• procedures pertaining to any accountability-related measurement or sampling operations

• forms used to record or to report measurement data and measurement results, including 

source data

• forms and notebooks used to record calibration data associated with any accountability 

measurement system

• forms and notebooks used to record quantities, volumes, and other data associated with 

the preparation of standards, both calibration and control, used in connection with 

accountability measurement systems

• forms and official memoranda used to record or report measurement control program 

data, control limit calculations, and out-of-control investigations

• forms listing and providing instructions associated with physical inventories

• forms and formal worksheets used in the calculation of SEID, ID, and active inventory 

values

• ledgers, journals, and computer printout sheets associated with the accountability 

system
NUREG-1280, Revision 2 126

• ledgers, journals, and computer printout sheets associated with the item control 

program, including TID usage and “attesting to” records

• DOE/NRC Forms 741 and 742 and NRC Form 327

• forms, memos, and reports associated with identification of, investigation of, and 

resolution of significant shipper-receiver differences

• loss indication and alleged theft investigation reports

• investigation reports pertaining to excessive IDs

• official reports containing the findings and recommendations of MC&A system 

assessments and any letters or memos pertaining to response actions to assessment 

team recommendations

• forms used for recording data associated with the item monitoring program

• monitoring program status or summary reports

• forms, worksheets, and calculations associated with process monitoring

• records of training sessions including date given, topics covered, name of instructors, 

names and signatures of those attending

• training, qualification, and requalification reports and records

The MC&A plan annex or appendix should list examples of MC&A forms that are retained. The 

retained records and reports should contain sufficient detail to enable the NRC inspectors to 

determine that the licensee has implemented the program and plan capabilities of

10 CFR 74.51(c) and has met the general performance objectives of 10 CFR 74.3 and 

10 CFR 74.51(a).

18.2 Program and Controls for Ensuring an Accurate and Reliable Record System

The MC&A plan should describe the controls used to ensure that records are accurate and 

reliable.

The record system also should provide a capability for easy traceability of all SNM/SSNM

transactions from source data to final accounting records.

The following topics should be addressed:

• the auditing system or program to verify the correctness and completeness of records

• the overchecks and balances for preventing or detecting missing or falsified data and 

records

• the plan for reconstructing lost or destroyed SNM/SSNM records
127 NUREG-1280, Revision 2

• the access controls used to ensure that only authorized persons can update and correct 

records

• the protection and redundancy of the record system such that any act of record 

alteration or destruction will not eliminate the ability to provide a complete and correct 

set of SNM/SSNM control and accounting information needed to achieve the 

performance objectives of 10 CFR 74.3

18.3 Commitments and Acceptance Criteria

In its MC&A plan, the licensee should provide definitive commitments that adhere to the 

regulatory requirements and meet acceptance criteria applicable to recordkeeping. A finding 

that the licensee’s MC&A plan for recordkeeping is acceptable and in accordance with 

10 CFR 74.59(g) will be based on, but not limited to, the following acceptance criteria:

• A record retention system is maintained for those records necessary to show that the 

MC&A system requirements of 10 CFR 74.51(c), have been met. Such records are 

retained for at least 3 years, unless a longer retention time is specified by 

10 CFR 74.15(b), by 10 CFR Part 75, or by a specific license condition. The records 

referred to in 10 CFR 75.22, “Accounting Records,” and 10 CFR 75.23, “Operating 

Records,” and generated during any period that the facility is under IAEA safeguards are

be retained for at least 5 years. Records of the following should be maintained current 

and should be retained for at least 3 years:

− management structure, MC&A job descriptions, and MC&A policies and 

procedures

− accounting source data records (normally consisting of shipping and receiving 

forms, physical inventory forms, and the forms used for initially recording 

measurement and measurement control data)

− records of shipments and receipts and investigations of significant 

shipper-receiver differences plus the information used to resolve them

− measurement data for receipts, shipments, discards, and inventory

− calibration of measurement systems, measurement control data, bias estimates, 

and the statistical analyses of the measurement control data

− data used to demonstrate that the measurement system performance achieves 

the SEID limit specified in 10 CFR 74.59(e)(5) and the data necessary to perform 

the material control tests required by 10 CFR 74.53(b)

− physical inventory listings and inventory work sheets

− calculations of detection thresholds for excessive IDs of a safeguards 

significance (i.e., any ID that exceeds three times the SEID and specified minimal 

quantities)
NUREG-1280, Revision 2 128

− calculations of the standard error of the ID and information used to reconcile an 

excessive ID

− reports of investigations and resolution of indications of loss of SNM/SSNM

− results of independent assessments and management action taken to correct 

any deficiencies identified

• Records will be maintained on the quantities of SNM/SSNM added to and removed from 

the process.

• The source data will be retained in its original form until the physical inventory and any 

subsequent ID investigations have been completed. After this time, any readable 

facsimile is acceptable for the remainder of the required retention period. All other 

records may be retained as hard copy, microfiche, permanent computer readable forms, 

or other permanently readable forms.

• The records will be retrievable, sufficiently complete and detailed to permit auditing all 

parts of the MC&A system, and traceable back to original source data.

• The records of the data that are the basis of the calculated SEID will permit traceability 

to the sources of the variances resulting from calibrations, bias adjustments, and random 

effects in the measurements. These records may be summaries of calibrations, bias 

tests, and variance monitoring data or control charts.

• The record system will have sufficient redundancy to enable reconstruction of lost or 

missing records so that knowledge of the SNM/SSNM inventory is always available. The 

primary records, as contrasted with duplicate or backup records, will be protected

against computer failure, fire or water damage, vandalism, and access by unauthorized 

persons.

• All retained MC&A records should be readily accessible so as to meet time restraints 

relative to their use. In general, the record retention system should possess the 

capability to retrieve records used for measurement control or accountability within 

24 hours if the record was generated within the past 12 months, and within 7 calendar 

days if generated more than 12 months ago. Physical inventory listings should be 

available within 24 hours for the latest two physical inventories. Item control records 

should be retrievable in time to satisfy the criteria discussed in Chapter 8 of this 

document.

• Overchecks or other controls including access controls for updating and correcting 

records are provided so as to prevent or detect errors in the records that would affect ID

and item location.

• Checks and balances are incorporated that are sufficient to detect falsification of data 

and reports that could conceal diversion of SNM/SSNM.

• Access to MC&A information will be controlled to provide deterrence and detection of 

theft, diversion, misuse, or radiological sabotage involving SNM/SSNM.
129 NUREG-1280, Revision 2

• Sufficient protection and redundancy of the record system is provided so that an act of 

record alteration or destruction will not eliminate the capability to provide a complete and 

correct set of control and accounting information that could be used to confirm the 

presence of SNM and SSNM, resolve indications of missing material, or aid in the 

investigation and recovery of missing material.

131 NUREG-1280, Revision 2

19. GLOSSARY

The following terms are defined in the context of (1) their usage in this document or (2) how they 

should be used if contained in the material control and accounting (MC&A) plans submitted in 

accordance with Title 10 of the Code of Federal Regulations (10 CFR) 74.51, “Nuclear Material 

Control and Accounting for Strategic Special Nuclear Material.”

ADDITIONS TO INVENTORY–Quantities of special nuclear material/strategic special nuclear 

material (SNM/SSNM), of a given material type code, added to a “plant” inventory and which, 

before such addition, were not part of the plant’s total possessed quantity for the material type 

code in question.

ANOMALY–An unusual observable condition (such as excessive discrepancies, missing items, 

broken tamper-indicating devices or other possible indicators) that might result from theft, 

diversion, or other misuse of SNM/SSNM.

ARTIFACT STANDARD–A container or item, of certified mass, having a size, shape, and mass 

that is representative of a particular type of process-related item or container. Weighing error 

caused by buoyancy is eliminated by the use of artifact standards for scale calibrations. 

ASSIGNED VALUE–A value assigned to a standard weight, standard material, or the like used 

for calibrating or controlling a measurement device or system for measuring SNM (e.g., mass, 

volume, SNM/SSNM concentration, or SNM/SSNM quantity). An assigned value may not 

necessarily be a certified value, but if not, it should be traceable to a certified standard. In any 

event, it is the best estimate of the standard’s true value.

CERTIFIED STANDARD–A standard weight, material, device, or instrument having an assigned 

value that is guaranteed to be within specified limits by a nationally or internationally recognized 

organization (e.g., bureau, laboratory) that issues or certifies standards.

CHECK STANDARD (BENCH STANDARD, WORKING STANDARD)–A standard, not 

necessarily traceable to a primary standard, that is used routinely (e.g., daily or weekly) to 

check (or verify) the reliability of a measurement device, instrument, or the like (including those 

of accountability measurement systems). Such standards are not, however, used for the actual 

calibration or control of accountability measurement systems.

COMBINED STANDARD ERROR–An error band derived from the respective standard error 

values associated with each of two measurements (usually independent of each other) 

performed on a given material quantity. For both measurement values (of the pair) to be 

regarded as being in agreement, they must not differ from each other by more than the 

calculated combined standard error, which is normally calculated by taking the square root of 

the sum of squared individual standard errors, as illustrated in the following equation:

Combined S.E. =

CONFIRMATORY MEASUREMENT–A measurement that confirms (within measurement 

uncertainty at the 95-percent confidence level) a previously established parameter (e.g., net 

weight, enrichment) associated with an SNM/SSNM item (or SNM/SSNM quantity), but which 
NUREG-1280, Revision 2 132

does not thoroughly verify the previously established element or isotope quantity assigned to 

such item. Confirmatory measurements are sometimes used as the basis for concluding that 

previous measurement values for plutonium (Pu), uranium (U), and U-235 or U-233 (or element 

and isotope) quantities are still valid.

CONTROL STANDARD–A standard that (1) is representative of the process material being 

measured and (2) is itself measured periodically to monitor for and to estimate any bias 

associated with the measurements of the process material in question. A control standard must 

be traceable to a primary standard or to a primary reference material.

CRITICAL MATERIAL CONTROL AND ACCOUNTING PROCEDURES–Those written 

procedures which, if not performed correctly, could result in a failure to achieve one or more of 

the eight general performance objectives of 10 CFR 74.3 and 10 CFR 74.51(a) or the program 

capabilities of 10 CFR 74.51(c).

DEPLETED URANIUM–Any uranium-bearing material whose combined U-233 plus U-235 

isotopic content is less than 0.70 weight percent (wt%) (relative to total uranium elemental 

content).

ENDING INVENTORY–For each material type code, the total itemized quantity of SNM/SSNM

possessed by a facility at the end of a material balance period, as determined by a physical 

inventory. The ending inventory quantity for any given material balance period is (by definition) 

exactly equal to the beginning inventory quantity for the next period.

ENRICHED URANIUM–Any uranium-bearing material which does not qualify as natural or 

normal uranium and whose combined U-233 plus U-235 isotopic content is 0.725 percent or 

higher by weight, relative to total uranium element content.

INVENTORY RECONCILIATION–The adjustment of the book record quantity of both element 

and fissile isotopes to reflect the results of a physical inventory. In the broad sense, inventory 

reconciliation also includes the activities of calculating (1) the inventory difference (ID) for the 

material balance period in question, (2) the uncertainty (i.e., the standard error of the inventory 

difference (SEID)) value associated with the ID, (3) the active inventory for the period, and 

(4) any bias adjustment or prior period adjustment associated with the ID value.

KEY MEASUREMENT SYSTEM–Any set of designated measurement systems (of the 

licensee’s choosing) which, based on the most recent previous period, account for at least 

90 percent of the total measurement variance contribution to the SEID. Included within the set 

of key measurement systems should be any system utilized to measure an SNM/SSNM quantity 

(during inventory period) greater than 25 percent of the active inventory, regardless of its 

contribution to the SEID.

MATERIAL BALANCE–The determination of an inventory difference. A comparison, on a 

measured basis, of beginning inventory plus additions to inventory to ending inventory plus 

removals from inventory, for a given control area (or combination of control areas) over a 

specified period of time. 

MATERIAL BALANCE PERIOD–The time span to which a material balance or physical 

inventory pertains.
133 NUREG-1280, Revision 2

MATERIAL TYPE CODES–Number codes for identifying basic material types with respect to 

source material (SM), SNM, and byproduct materials. The Nuclear Materials Management and 

Safeguards System (NMMSS) uses these codes to track U.S.-owned and U.S.-possessed 

materials worldwide. For SNM, eight material type codes have been assigned as follows:

CODE MATERIAL TYPE

10 Depleted Uranium

20 Enriched Uranium (*)

50 Plutonium

70 Uranium-233 (**)

81 Normal Uranium

83 Plutonium-238 (***)

88 Thorium

89 Uranium in Cascades 

* For U.S. Department of Energy/U.S. Nuclear Regulatory Commission (DOE/NRC) Form 742, material code 

20 has four subcodes to denote enrichment range: E1, E2, E3, and E4. For NRC Form 327, material code 

20 has two subcodes: LEU (low-enriched uranium) and HEU (high-enriched uranium).

** Uranium materials should be regarded as material code 70 if the U-233 isotopic abundance is greater than 

(1) 10.00 wt% relative to total uranium elemental content or (2) both the U-233 isotopic abundance is greater 

than the U-235 isotopic abundance and the U-233 isotopic abundance exceeds 5.00 wt% relative to total 

elemental uranium content; otherwise report as material code 10, 20, or 81, as appropriate.

*** Plutonium materials should be regarded as material code 83 if the Pu-238 isotopic abundance is greater 

than 10.00 wt% relative to total plutonium elemental content; otherwise, report as material code 50.

MEASURED DISCARD–A batch or quantity of waste whose SNM/SSNM content has been 

determined by measurement that (1) has been shipped to a disposal site, released to the 

environment, or stored on site and (2) has been taken off the accounting ledgers as part of the 

current inventory of possessed SNM/SSNM.

MEASUREMENT CONTROL SYSTEM–A managed system for monitoring and controlling both 

accuracy and precision of SNM/SSNM accountability measurements.

NATURAL URANIUM–Any uranium-bearing material whose uranium isotopic distribution has 

not been altered from its naturally occurring state. Natural uranium is nominally 99.283 wt% 

U-238, 0.711 wt% U-235, and 0.006 wt% U-234. However, the terms “natural uranium” and 

“normal uranium” are practically used interchangeably for NMMSS purposes in the utilization of 

material code 81 for source material other than thorium.

NORMAL URANIUM–Any uranium-bearing material having a uranium isotopic distribution that 

can be characterized as being (1) 0.700 wt% to 0.724 wt% in combined U-233 plus U-235 and 

(2) at least 99.200 wt% in U-238. (Note: All natural uranium having a U-235 isotopic 

abundance in the range of 0.700 wt% to 0.724 wt% is normal uranium, but not all normal 

uranium is natural uranium.) See NATURAL URANIUM.
NUREG-1280, Revision 2 134

POINT-CALIBRATED MEASUREMENT SYSTEM–A measurement system in which the 

measurement value assigned to an unknown measured by the system is derived from the 

response obtained from the measurement of a representative calibration standard that was 

measured along with (i.e., at the same time as) the unknown. The standard must undergo all 

the measurement steps (e.g., aliquoting, sample pretreatment) in the same manner as the 

unknown. Point-calibrated measurement systems can be regarded as bias free, provided that 

adequate controls are in place to ensure the validity of the standard’s assigned value.

PRIMARY STANDARD–Any device or material having a characteristic or parameter (e.g.,

mass, uranium concentration, uranium isotopic distribution) whose value is certified (within a 

specified uncertainty) by a nationally or internationally recognized bureau, laboratory, or similar 

organization that issues or certifies standards.

PRIOR PERIOD ADJUSTMENT–Any correction (i.e., adjustment) to an ID value because of a 

correction applied to a component of beginning inventory after the inventory period started. 

Such corrections may result from resolution of a shipper-receiver difference on material 

received during a prior inventory period, correction of a recording error, or the like. Because 

these types of corrections have nothing to do with current period losses or errors, and because 

the official beginning inventory value is not adjusted, an adjustment to the ID value (derived 

from the ID equation) is necessary to obtain an ID that reflects only current period activity.

RESIDUAL HOLDUP–Any SNM/SSNM that remains within processing equipment (including 

ventilation filters and ductwork) after system draindown or cleanout. If, at the time of physical 

inventory, the total quantity of residual holdup is significant, such holdup must be measured (or 

estimated on the basis of partial measurements and engineering calculations) and included in 

the physical inventory listing. The calculation of the SEID must include the uncertainty 

associated with a total measured or estimated residual holdup quantity.

RESOLUTION OF AN INDICATOR–A definitive determination (with auditable evidence) by the 

licensee that an indicated possible theft or loss of uranium or plutonium was a false indicator.

SHIPPER-RECEIVER DIFFERENCE–The difference between what a sending facility (i.e., 

shipper) claims was contained in a shipment of SNM/SSNM and what the receiving facility 

claims was received, where both the shipper's and receiver's values are based on 

measurement.

SIGNIFICANT QUANTITY OF SNM OF MODERATE STRATEGIC SIGNIFICANCE–More than 

1 formula kilogram of SSNM, or 10,000 grams or more of U-235 contained in uranium enriched 

to 10 percent or more, but less than 20 percent in the U-235 isotope. (Note: For statistical 

sampling plans, however, the significant quantity is conservatively set to 1 formula kilogram for 

SSNM and 10,000 grams U-235 for Category II amounts of low-enriched uranium.

STANDARD–See definitions for CERTIFIED STANDARD, CHECK STANDARD, CONTROL 

STANDARD, PRIMARY STANDARD, and STANDARD REFERENCE MATERIAL.

STANDARD DEVIATION–The random error (at the 67-percent confidence level) associated 

with a single value of a data set, which in turn is also a measure (or indication) of the precision 
135 NUREG-1280, Revision 2

relating to a set of measurements (or set of data) pertaining to the same item or sample of 

material. Standard deviation is calculated as follows:

standard deviation = S = 

where

n = number of measurements performed

xi = the value obtained for the ith measurement for i = 1, 2, 3 .......n

 = the average value for all n measurements

STANDARD ERROR–The random error (at the 67-percent confidence level) associated with the 

average, or mean, value of a data set derived from repetitive determinations on the same item 

or sample. Mathematically, standard error is the standard deviation divided by the square root 

of the number of individual measurements used to derive the mean value.

STANDARD REFERENCE MATERIAL–A material or substance that qualifies as a primary 

standard and whose concentration with respect to a nuclide or isotope, a chemical element, or 

chemical compound is certified within a specified uncertainty.

SYSTEMATIC ERROR–A unidirectional error that affects all members of a data set. The terms 

“bias” and “systematic error” are often interchanged. However, any determined bias (i.e., a bias 

estimated from control standard measurements) has an uncertainty value associated with it. 

Thus, after correcting for any estimated bias, the uncertainty of that bias can be regarded as a 

systematic error. If an estimated bias is not applied as a correction, the combination of the bias 

plus its uncertainty should be regarded as the systematic error.

VERIFICATION MEASUREMENT–(1) A nondestructive assay measurement of an item 

conducted to verify that a previous nondestructive assay measurement value for isotope content 

of that item is still valid or (2) the reweighing and resampling of an item, batch, lot, or sublot and 

performance of chemical assays of the resample for element and isotope concentrations so as 

to verify a previously measured value for element and isotope content of the item (batch, lot, or 

sublot). Verification is achieved if the original and verification measurement values (for element 

and isotope quantities) agree within the range of measurement uncertainty (at the 95-percent 

confidence level).

137 NUREG-1280, Revision 2

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NUREG-1280, Revision 2 138

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UNITED STATES 

NUCLEAR REGULATORY COMMISSION

WASHINGTON, DC 20555-0001

--------------------

OFFICIAL BUSINESS
NUREG-1280, Rev. 2

Draft

Acceptable Standard Format and Content for the Material Control and 

Accounting Plan Required for Strategic Special Nuclear Material