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Global Best Practices for Material Control and Accountability (MCA)

Special International Workshop on Global Best Practices in Materials Accountancy, Control
June 7 – 11, 2004
Prague, Czech Republic

MCA1. Identify MCA program terms, principles, and objectives.
Because clear and precise definitions of terms, principles, and objectives are necessary for effective communication, a glossary should be prepared that concisely defines the terms, principles, and objectives used by the State.

Principles should be established that promote accurate, complete, and timely data and records on nuclear material accountability and that support the ability to verify data independently.

Objectives should be identified that detect and deter the loss, theft, and diversion of nuclear material; meet international safeguards agreements and standards as well as regional and national legislation and regulations, and other requirements such as bilateral agreements and contractual agreements; and form the basis for an effective physical protection system. A graded approach is a useful tool to help meet these objectives.

MCA2. Establish an effective MCA organization.
Program administration, implemented by nuclear material sites, should ensure that the program addresses critical functions, establishes appropriate authorities and responsibilities, supports the nuclear material missions at the site, and facilitates integration with other programs such as operations and health and safety. It should also address strategic planning for new systems and technologies, and changes in facility designs. Program administration should provide training and qualification for those who perform control and accounting functions and use employee feedback to strengthen system performance.

Best practices for the structure of an MCA organization:

MCA3. Develop, implement, and validate measurement methods capable of providing the required levels of accuracy and precision.
Nuclear material inventory quantities should be established upon creation or receipt of a new item, or when there are changes in quantity, physical form, or chemical form. These quantities should be reestablished periodically to reduce uncertainties such as when there are improved measurement capabilities. Measurement methods, instrumentation, and personnel should be subject to a formal qualification program. A measurement control program should be established that employs reference materials and standards; identifies precision and accuracy values, monitors; monitors and controls measurements; and quantifies measurement errors used in the statistical evaluation of material control indicators. The nuclear materials site is responsible to implement the measurement program in a way that meets the stated objectives of the state regulatory authority.

Sources of measurement errors should be identified and, to the extent possible, reduced or mitigated. Examples of this include effects of external factors such as humans, humidity, and heat. Measurement systems and people operating them should be qualified and benchmarked (for example, blind samples and external sample exchange programs).

Ideally, nuclear materials measurement methods should be chosen to minimize the uncertainties of the nuclear material accountability value. However, this is not always practical given the cost and amount of material. When determining what measurement methods to use, several parameters should be considered, including: nature of operations, availability of equipment, cost, personnel exposure, precision and accuracy goals (both national and international), field conditions, material attributes, material containers, and the material matrix.

Challenging areas for measurements are related to their potential to be used as a diversion path or to negatively impact the ability of the facility to draw an accurate material balance. These areas include waste streams and material in process holdup. Waste streams should be continuously monitored and measured using methods capable of detecting diversion of nuclear materials. Waste measurements should be capable of providing sufficient precision and accuracy to meet national and international requirements and provide sufficient information for both MCA and waste management programs in the units required.

A wall-to-wall hold-up measurement program should look at material in hold-up in the expected locations and also in unexpected locations. When possible, equipment hold-up measurements should be validated by using other measurement techniques, after the equipment has been removed and either completely dissolved or cleaned out.

Best practices for nuclear material measurement systems:

MCA4. Establish a complete, accurate, and timely record of the entire nuclear material inventory.
The accountability system should track the total quantity of nuclear material and record the characteristics, location, and unique item identity for each nuclear material item. It should be able to provide a complete audit trail for all nuclear materials from receipt through disposition, including documentation of all nuclear material transactions. Measures should be established and checks implemented to ensure data accuracy and detect any unauthorized access to data. Accountancy is the responsibility of each nuclear materials site. The regulatory body should ensure standardization of data from each site, oversee the work and compile a complete state-wide inventory.

The nuclear material item should be established as the basic accounting entity. The item should have a unique identity, and the accounting records should reflect the characteristics and location of the item.

The fundamental accounting structure for nuclear material is the material balance area (MBA). MBAs should be established to localize inventory differences and meet international reporting requirements, while reducing, to the extent possible, the burden of the operator in generating reports.

Best practices for establishing an MBA:

Best practices for accounting systems:

MCA5. Establish a system for materials control using well defined geographical areas within the site.
Nuclear materials should be used, processed, and stored only in areas that have been identified for these purposes and that have appropriate physical and administrative controls. Thus, each nuclear materials site should establish well-defined geographical areas wherein the location and quantity of all nuclear materials are identified and controlled. Area boundaries should not overlap. The material types, forms, and quantities permitted in each area should be precisely specified. All movements of people and materials into and out of these areas should be carefully monitored and controlled. Material transfers between areas should be based on measured values, and waste streams should be monitored.

Each site should implement appropriate physical security and administrative controls to permit controlled access to the area by personnel and prevent any unauthorized access. Alarms and procedures to assess anomalies should be established.

Not all the equipment necessary for an effective material control program has to be "high tech;" the application of inexpensive tamper-resistant seals coupled with a strong material surveillance program are sufficient for maintaining continuity of knowledge of the material in inventory.

Containment and surveillance measures provide assurance that the integrity of nuclear material values is maintained. Unattended remote monitoring and measurement systems for containment and surveillance purposes can provide several benefits, including reduced need for operator and inspector access, greater transparency, greater flexibility and possibility for on-line measurements, more accurate and timely results, reduced operational costs, and reduced personnel radiation exposure.

Best practices for material control:

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