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STATE SYSTEMS OF ACCOUNTING AND
CONTROL
Mr. Dirk Schriefer
INTRODUCTION
When a country embarks upon a program of nuclear activities, however modest, the government will generally find
it necessary to establish a framework of controls to ensure that its safety and non-proliferation objectives are
met. Usually a separate governmental body, such as a Nuclear Regulatory Authority, is established and given the
authority to oversee the nuclear programme. Aspects to be controlled are:
· radiation protection of radiation workers and the population;
· use and transportation of radioactive and nuclear material;
· radioactive waste management;
· licensing of nuclear installations and their engineered nuclear safety;
· physical protection of nuclear material and installations to prevent theft, sabotage and other misuse;
and
· safeguards.
Although these functions have a tendency to reinforce one another, in practice they might be carried out by one
single body or by several. Most of them satisfy primarily national needs. The assurance that the nuclear programme
serves exclusively peaceful purposes is an international objective which is achieved through implementation of
IAEA safeguards.
Organizational and technical arrangements to be made by a State in achieving both, national objectives and international
safeguards objectives, form the State System of Accounting For and Control of Nuclear Material (SSAC). Such a system
consists usually of three major components: a legal framework, a State-level component and facility-level components.
Objectives and principal requirements for the State System of Accounting for and Control of Nuclear Material, that
arise from the Treaty for the Prohibition of Nuclear Weapons in Latin America and the Caribbean (“Tlatelolco Treaty”),
the Treaty on the Non-Proliferation of Nuclear Weapons (“NPT”) and Safeguards Agreements with the IAEA, will be
discussed here.
A safeguards agreement conforming to INFCIRC/153 (Corrected) is required to provide that “... the State shall establish
and maintain a system of accounting for and control of all nuclear material subject to safeguards under the agreement”
which calls for arrangements between the IAEA and the State on a “system of records” and a “system of reports”.
The establishment of an SSAC is a vital element in carrying out international safeguards. Also as an important
tool to improve the operations of nuclear facilities an SSAC assists facility operators to improve their effectiveness
and efficiency. An SSAC may have, inter alia, the following objectives:
1. A national objective, to account for and control nuclear material in the State and to contribute to the detection
of possible losses, or unauthorized removal of nuclear material.
2. An international objective, in particular, to provide the essential basis for the application of IAEA safeguards
pursuant to the provisions of an agreement between the State and the IAEA.
While systems designed specifically for one or the other of these objectives may differ in some details, many technical
elements are the same and would contribute to the attainment of both objectives. The basic elements of an SSAC
are set forth in paragraph 32 of INFClRC/153 (Corrected) which calls for an SSAC to be based on a structure of
material balance areas and includes measures to be specified in the Subsidiary Arrangements.
ELEMENTS OF A STATE SYSTEM
In outlining the State level component of an SSAC, the organizational and functional elements of an SSAC can be
addressed in the following six major areas, each of these will be discussed briefly:
1. Authority and Responsibility
2. Laws, Regulations and Other Measures
3. SSAC Information System
4. Establishment of Requirements for Nuclear Material Accounting and Control
5. Ensuring Compliance
6. Technical Support.
Authority and Responsibility
A State will formulate policy, define objectives and assign responsibilities appropriate for both national and
international objectives. IAEA/SG/INF/2 outlines quite clearly the authority and responsibilities of a State with
respect to the SSAC.
A State should:
1. Define its objectives in establishing an SSAC.
2. Designate a nuclear material accounting and control authority with the responsibility for:
· establishing provisions governing the possession, transfer and use of nuclear material;
· ensuring that the State’s nuclear material accounting and control objectives are met;
· serving as the point of contact in implementing Safeguards Agreements concluded with the IAEA and
· developing and implementing nuclear material accounting and control procedures for the State to discharge
its obligations under IAEA Safeguards Agreements.
3. Establish appropriate arrangements for the prompt notification of responsible Government authorities in the
event of losses, unauthorized use or removal of nuclear material.
Laws and Regulations
Given an SSAC objective to detect loss, theft or diversion of nuclear material, a State needs to have clear knowledge
of what material is under its jurisdiction, where it is located, what use is being made of it and who is responsible
for it. Further, the State will need measures to assure that this information about the material is accurate. The
basis of obtaining this information and for providing assurance of the accuracy of the information can be provided
through laws and regulations in the following area:
1. definition of the starting point for accounting for and control of nuclear material and the conditions for termination
or exemption from accounting and control.
2. establishment of conditions for possession and use of nuclear material, including establishment of criteria
and requirements for a system of accounting for and control of the material.
3. establishment of requirements for both routine and special reports to the state of information pertinent to
nuclear material, including reports of changes in the facility and incidents affecting material accounting and
control and reports of incidents involving loss of nuclear material.
The State should make and regularly review the necessary laws, regulations or other measures to ensure that the
requirements for nuclear material accounting and control are met throughout the area within its jurisdiction. These
measures should include the requirements in respect of nuclear material, facilities, international transfers.
Information System
The State should establish and maintain an SSAC information system with the following main activities:
1. recording and processing of information on nuclear material, provided by facility operators and reported to
the State Authority;
2. collecting, processing and recording of the information by the State Authority and preparing of reports for
evaluation internally and for submission to satisfy international and possibly national obligations;
3. handling of other information to be received from and sent to the IAEA and others such as shippers or receivers
in other states.
The State Authority will need to handle various kinds of information1 to exercise control of the possession, use
and disposition of the nuclear material under its jurisdiction. Regardless of size and complexity, however, a State
Authority information system will need to include at least four categories of information:
· Design information records;
· Nuclear material inventory and transaction records;
· Activity and operations reports and records and
· Records and reports to and from the IAEA.
Establishment of Requirements for Nuclear Material Accounting and Control
While the functional separation between the State level and the facility level may vary from State to State, in
general the State level establishes the requirements and criteria for the SSAC and the facility operator implements
the system in compliance with the State requirements and criteria. These technical requirements and criteria to
be established are outlines in IAEA/SG/INF/2 and include the following:
1. Starting point, termination and exemption of accounting and control
2. Categorization of nuclear material
3. Material balance areas
4. Records and reports system
5. Measurement system
6. Nuclear material flow
7. Physical inventory taking
8. Shipper/receiver differences
9. Application of containment and surveillance measures
10. International transfers of nuclear material.
Ensuring Compliance
Assurance of operator compliance with the requirements and criteria established for an SSAC by the State Authority
can be achieved only by a comprehensive audit and inspection programme2. Such a programme should have the following
objectives:
1. ensure that the capability and performance of the facility SSAC satisfy the requirements and criteria established
by the State Authority to meet the State’s international obligations as well as to meet national objectives for
accounting for and control of nuclear material and
2. assure through verification by the State Authority that the accounting and control measures implemented by the
facility operator are effective and to conclude that there has been no unauthorized removal or use of nuclear material.
Technical Support
Training of staff
Training of personnel responsible for accounting for and nuclear material, at State and facility levels, is critical
for the successful operation of an SSAC. In many countries, first the State Authority needs to train its own staff,
to be able to achieve its selected objectives. In this connection, much use can be made of the training courses,
fellowships and scientific visits offered by the IAEA. When the training of the State Authority is completed, the
facility personnel can also make use of the training courses offered by the IAEA at its Headquarters or in other
Member States.
Technical Assistance to the Plant Operator
The State should facilitate the provision of adequate technical assistance, from external sources if necessary,
to facility operators in the area of material accounting and control in order to enable the operator to fulfill
the requirements placed on him by the State3. This assistance could, for example, help in establishing adequate
records systems and measurement systems which may incorporate non-destructive assay techniques as well as data
processing and analysis procedures. Assistance should be given also to acquire international standards and to establish
containment and surveillance measures.
TECHNICAL REQUIREMENTS FOR NUCLEAR MATERIAL ACCOUNTING AND CONTROL SYSTEMS
The technical requirements of an SSAC will depend, among other things, on the types of nuclear activity and on
the form and quantity of nuclear material. A State with extensive bulk handling facilities (enrichment, conversion,
fabrication, reprocessing) should have a large SSAC including all of necessary requirements, while States with
only research reactors or power reactors would not have such extensive requirements.
Starting point, termination and exemption of accounting and control
The Authority should consider the following:
1. the starting point for the application of accounting for and control of nuclear material should be at least
as early in the nuclear fuel cycle as is required by the State’s international obligations;
2. accounting and control should be terminated on nuclear material upon determination under the State’s international
obligations that the material has been consumed or has been diluted in such a way that it is no longer usable for
any nuclear activity or has become practicably irrecoverable and
3. the conditions for exemptions from and termination of accounting and control should be specified, consistent
with the State’s international obligations.
In the case of a Safeguards Agreement based on the Tlatelolco Treaty or the NPT, safeguards are not applied to
material during mining or ore processing activities. When nuclear material of a composition and purity suitable
for fuel fabrication or for isotopic enrichment leaves the plant or the process stage in which it has been produced,
or is imported into the State, the nuclear material becomes subject to the full safeguards procedures specified
in the Safeguards Agreement.
The provisions for termination and exemption of accounting and control are specified in the Safeguards Agreements4.
Categorization of nuclear material
Categorization of nuclear material should be established in order to enable an appropriate balance to be maintained
among the significance of different materials. This categorization should consider characteristics such as the
material type and isotopic composition (including in particular the content of fissile isotopes), the irradiation
level and the measurement methods and uncertainties associated with the material. The categorization should be
used, in conjunction with information on quantities of nuclear material involved, in specifying the intensity if
accounting and control measures, including the taking of physical inventories and the determination of MUF. For
example, plutonium and high enriched uranium could be in the highest category, followed by low enriched uranium,
then natural uranium and finally depleted uranium and thorium.
Materials which can be converted to nuclear explosives without transmutation or further enrichment are defined
as direct-use materials, while materials which must be enriched or transmuted to form direct-use materials are
defined as indirect-use materials.
Direct-use materials include plutonium (all isotopes), uranium-233, uranium enriched to 20% or higher of the isotope
uranium-235, and mixtures of these. Indirect-use materials include forms of uranium enriched to less than 20% uranium-235,
thorium and mixtures of these. Categorization of nuclear materials is strongly related to the concepts of quantity
of safeguards significance and conversion time.
Material Balance Areas
In order to organize a system of nuclear material accountancy, the concept of material balance area (MBA) is applied.
An MBA is, exactly as its name would suggest, a physical area in which a balance of the nuclear materials can be
made.
The SSAC should establish the factors to be taken into account and the criteria to be met in the determination
of each MBA. This must include the Key Measurement Points (KMP), containment and surveillance possibilities (particularly
to help ensure the completeness of flow measurement) and the accuracy with which the material balance can be established.
The Authority should approve the facility MBAs. States which concluded a Safeguards Agreement with the IAEA based
on INFCIRC/153 (e.g., Tlatelolco, NPT) should use a system of MBAs which is compatible with the system agreed in
the Subsidiary Arrangements to the Safeguards Agreement between the IAEA and the State.
Records and Reports System
The Authority should establish the requirements for accounting and operating records and reports for each MBA to
provide relevant data on nuclear material transactions and operations that affect the accounting for and control
of nuclear material.
Accounting records - a set of documents kept at each nuclear facility, showing the quantity of each type of nuclear
material present, its distribution within the facility and any changes affecting it. This includes the records
showing measurement results.
Operating records - a set of documents kept at each facility consisting of organized data on the operation of the
facility in connection with the use or handling of nuclear material. The operating records of a nuclear reactor
show, for example, the integrated thermal power produced by the reactor for a given period and the associated data
of the reactor operation for that period. The operating records of a bulk handling facility include quality control
on the measurements.
Accounting report - a statement to the IAEA on the status of nuclear materials subject to safeguards in a defined
environment and on the changes in that status since the previous report. Accounting reports are submitted by the
State at times specified in the agreements or subsidiary arrangements.
For Tlatelolco and NPT safeguards three types of routine accounting reports for each MBA are called for: Inventory
Change Reports (ICR), Material Balance Reports (MBR), Physical Inventory Listings (PIL).
Measurement System and Control
The Authority should establish requirements for a measurement system and measurement uncertainties, including provisions
for the determination of nuclear material received, produced, shipped, lost or otherwise removed from inventory
and for the determination of inventory quantities based on sampling and chemical or non-destructive analysis, as
appropriate.
The measurement system includes personnel, procedures and apparatus used for accounting measurements and should
provide for:
· Identification of the key measurement points in the process and the characteristics of the nuclear material
to be measured;
· Specification of measurement performance desired;
· Specification of the measurement technique(s) to be employed;
· Equipment maintenance provisions and procedures;
· Operator’s qualifications and provision for training;
· Calibration standards and procedures;
· Routine measurement and data analysis procedures;
· Procedures to control the quality of measurements and to maintain performance at the desired level.
A measurement control programme is to be established with the objectives of ensuring that the routine operation
of the measurement systems is adequate; that measurement components are re-calibrated at appropriate intervals;
that random and systematic errors are properly estimated for propagation so that the limits of measurement uncertainties
associated with any “material unaccounted for” (MUF) can be established; and that clerical errors are, as far as
practicable, detected and corrected. The Agency’s technical conclusion depends, among other things, on these measurement
uncertainties.
Nuclear Material Flow
The Authority should establish requirements, when relevant, for the accounting and control of the flows of nuclear
material, taking into account the degree of assurance to be obtained from containment and surveillance measures.
Requirements for measuring, including corresponding uncertainties, and for identifying receipts, shipments, and
transfers within a facility should be defined as necessary to provide for periodic material balances.
Physical Inventory Taking
The physical inventory taking is the bench mark of nuclear material accounting and control since it provides conclusive
evidence of the physical presence of the material.
The Authority should establish the requirements, including the completeness, frequency and allowable limits of
measurement uncertainty, for the different categories of material, of the physical inventories to be taken by the
facility operators, taking into account the degree of assurance to be obtained from containment and surveillance
measures. Provisions should be made to notify the IAEA in advance of dates when physical inventories will be taken.
Authority requirements for physical inventories should include:
1. a system of stratification of the nuclear material in the inventory;
2. criteria for accepting measurements already made, including provision for the use of seals to assure the validity
of the previous measurements;
3. criteria for limiting the quantity of nuclear material in difficult-to-measure forms;
4. criteria for complete or partial clean-out of plants, including criteria to determine the degree of completeness
of the clean-out required and methods to assure that those criteria are met and
5. criteria for taking of a special physical inventory in case, for example, unusually large MUF, an operating
accident or unusual loss.
While the physical inventory taking provides the evidence of the physical presence of the nuclear material, the
material balance based on this inventory permits the determination of whether significant losses or discrepancies
have occurred undetected. It is usually immediately after the physical inventory taking (and verification) that
the material balance will be “closed”. All data from all components of the material balance must be used, and all
data must be based on measurements of known uncertainties, so that any discrepancy may be evaluated and meaningful
conclusions reached.
Shipper/Receiver Differences
The difference between the quantity of nuclear material as stated by the shipping material balance area and as
measured at the receiving material balance area is called the “shipper/receiver difference”. The Authority should:
1. establish the requirements for identifying, reviewing, evaluating and resolving differences in all shipper/receiver
measurements and for deriving the limits of measurement uncertainty of transfers between MBAs within its control
and
2. describe the procedures to be followed when shipper/receiver differences or their limits of measurement uncertainty
exceed specified values.
Containment and Surveillance Measures
Containment and surveillance measures are necessary or convenient in some situations to enable the Authority, as
part of its nuclear material control function, to monitor flows, to confirm the integrity of stores, and in general
to detect when material present in an MBA or facility is removed without appropriate accounting action. When containment
and surveillance or accountancy measures have failed or indicate possible unauthorized removal of nuclear material,
the facility operator should be required to conduct a comprehensive investigation and to take appropriate corrective
actions which may include re-measuring of corresponding inventories.
Review of the design of facilities permits the most cost effective combination of accountancy, containment and
surveillance procedures, equipment and features of facilities to be determined. C/S measures will become more important
for large facilities of the future where safeguards objectives cannot be realized exclusively through nuclear material
accountancy measures.
International Transfers of Nuclear Material
The Authority should establish requirements for international transfer of nuclear material with time specifications
on necessary arrangements for advance notifications, accounting and control responsibility, and reporting on nuclear
material shipped and received.
There are some practical problems involved in international transfers especially from the international safeguards
viewpoint of the IAEA. Two of these in particular are transfer of accounting and control responsibility and continuity
of material identity.
States involved in international transfers should agree upon the point of the transfer of accountability and control
responsibility. Shipping states will provide shipment identification, i.e. batch identity, which will be reported
to the IAEA in ICRs. Receiving states should use this same identification in reporting receipt of the material
in their ICRs even though the receiving state may use a different identity for domestic purposes. This will enable
the IAEA to close the record on an international shipment.
ACKNOWLEDGMENT
This paper is based on previous documents on the same or similar subjects. Recently, sessions in a regional training
course in Japan, 1995, addressed a similar subject: IAEA Requirements to SSAC, by K. Murakami, and: Principal Elements
of an SSAC at State and facility-levels, by J. Hill.
REFERENCES
1. IAEA Safeguards Glossary, IAEA, Vienna, 1987, IAEA/SG/INF/1 (Rev. l )
2. Guidelines for States’ Systems of Accounting for and Control of Nuclear Material, IAEA, Vienna, 1980, IAEA/SG/INF/2
3. The Structure and Content of Agreements between the Agency and States required in connection with the Treaty
on the Non-Proliferation of Nuclear Weapons, INFCIRC/153 (Corrected)
4. Systems of Accounting for and Control of Nuclear Material, IAEA Bulletin, Vienna, 1975
___________________________
1 The size, cost and type (i.e. manual or computer) of such a system will depend on the volume of
information to be handled which will, in turn, depend on the type and variety of nuclear materials and facilities
in a State. One measure that has been used in this context is the number of entry lines reported to the IAEA each
year. This number is obtained by summing the lines in the relevant reports to the IAEA for a year (i.e. Inventory
Change Reports and Physical Inventory Lists). A rough indication of the need for a computer system is that if the
entry lines in the IAEA report are more than 10,000, some type of computer may be needed for effective data handling.
2 The objectives adopted by the State depends upon the degree that the State wishes to delegate accounting and
control responsibilities. Some States, for example, may limit inspections to routine examination of records; others
may integrate State inspection activity with those of the IAEA in order to minimize overall cost and maximize effectiveness
of particular inspections; and others may elect to carry out an inspection program that provides independent assurance.
Inspection activities associated with safety, radiation protection and construction might to some extent be coordinated
with accounting and control inspections in order to minimize intrusiveness and cost and to improve effectiveness.
In any case, the State should recognize that the IAEA includes both objectives in its inspection programmes and
does conduct independent verification activities in its inspections as well as the initial design reviews. IAEA/SG/INF/2
provides some inspection activity guidelines to assist States in achieving both of the states objectives.
3 At the facilities which perform measurements related to safeguards objectives, especially measurements for nuclear
material accounting for in bulk-handling facilities, considerable assistance to the operator may be necessary.
Measurements and measurement control programmes at such facilities on which much of the success of the SSAC depends
can be quite complex. Evaluation of SSAC programme results also can be complex. The IAEA has published several
volumes of the Safeguards Technical Manual which could be of assistance to States and facility operators. In addition
a series of Safeguards Technical Reports is being prepared to provide assistance in establishing SSACs at various
types of facilities. Some of these documents are listed in the references.
4 See also paragraphs 11 and 13 of INFCIRC/153.
© 1998-2000 El Organismo para la Proscripción de Armas Nucleares
en la América Latina y el Caribe (OPANAL) . Todos los derechos reservados.
The Agency for the Prohibition of Nuclear Weapons in Latin America and the Caribbean (OPANAL). All rights reserved.