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Nuclear Safeguards Education Portal

Nuclear Material Accountancy

All nuclear material in a state under comprehensive safeguards must be accounted for at all times through a material accountancy and containment and surveillance system. This allows the IAEA to verify the correctness of all accounting information and to ensure a state is compliant with its international obligation.

Accidental Gain: When extra unknown nuclear material is found while taking inventory of a storage area. More.
batch: A portion of nuclear material handled as a unit for accounting purposes at a KMP and for which the composition and quantity are defined by a single set of specifications or measurements. An example of this would be if the material had the same element concentration, enrichment, or came from the same production run. More.
Batch Data: The total weight of each element of nuclear material and isotopic composition when appropriate. More.
Bulk Accounting: An inventory recording method that generalizes the counting for small items when counting is not feasible. Examples: powders and solutions. More.
Cumulative MUF : The algebraic sum of the MUFs for a material balance area over time. More.
Cumulative SRD: The algebraic sum of the shipper/receiver differences for a material balance area over time. More.
Hold-up: Nuclear material that remain in a plant after shutdown in parts such as process equipment or piping. More.
IAEA interim inventory verification : An IAEA inspection that doesn’t coincide with the ending date on the material balance period and doesn’t need to include all the nuclear materials on the material balance area. More.
IAEA inventory verification: An inspection activity carried out to confirm that the amount of nuclear material actually present at a given time within a material balance area (MBA). More.
IAEA physical inventory verification (PIV) : An inspection activity that follows closely, or coincides with, the physical inventory taking by the operator and closes the material balance period. More.
Item accounting: An inventory taking method that is used for objects that are countable such as fuel rods or other pieces of equipment. More.
Key measurement point (KMP) : A location where nuclear material appears in such a form that it may be measured to determine material flow or inventory. More.
Material balance area (MBA): An area in a facility where the nuclear material quantification can take place and the inventory of said materials can be accounted for in between movement around or from the facility. More.
Material balance period (MBP): The time between two consecutive inventory measurements as reflected inside the MBR. More.
Material unaccounted for (MUF) : A mathematical equation for the differences in increase and decrease of inventory as well as what is found initially and finally. The difference of all four parts is the MUF. More.
Matrix: The non-nuclear part of nuclear material. More.
Measurement system: Procedures, personnel and equipment used for determining the quantities of nuclear material received, produced, shipped, lost or otherwise removed from inventory, and the quantities on inventory. More.
Nuclear Loss: The loss of nuclear material due to half-life and decay or transformation into other elements or isotopes. More.
Nuclear material accountancy: The practice of nuclear material accounting as implemented by the facility operator and the State system. More.
Nuclear material accounting: The process and activities that are performed to measure the nuclear material presented within measuring areas and the changes that are found within defined periods. More.
Physical inventory: The quantified amounts of nuclear material that is on hand at a given time within a facility. More.
sampling from bulk material: Quantification of an object, such as a container, to obtain the mass or some other property for recording. More.
Shipper/receiver difference (SRD) : The difference that is found between the amount of nuclear material that is stated from the shipping point and the measurement made at the receiving point. More.
State Systems for Accountancy and Control: The State System of Accounting for and Control of Nuclear Material (SSAC) comprises the organizational arrangements at the national level which may have both a national objective to account for and control nuclear material in the State and an international objective to provide the basis for the application of IAEA safeguards under an agreement between the State and the IAEA. More.
Strategic point : A location of high security interest in the State which is a potential target for terrorist attacks using nuclear material or other radioactive material, or a location at which nuclear material or other radioactive material that is out of regulatory control is located. More.
stratum: Grouping of items based on similar physical and chemical characteristics. More.