Material Control and Accounting
In the early years of the nuclear age all special nuclear material (SNM) was owned by the Federal government. It was a valuable commodity and the Atomic Energy Commission (AEC) had a financial duty to keep track of the material as it was lent to various scientists and organizations for their use. To accomplish this, procedures for tracking and accounting for the SNM, much as a bank account for money, were established. Unlike money, however, the amount of SNM cannot generally be counted but must be determined by weight and assay, as with precious metals such as gold and silver.
The government no longer owns all SNM. The Department of Energy, a successor to the AEC, owns SNM and still has some on loan to other agencies and companies; however, the NRC, which inherited the regulatory functions of the AEC and is independent of DOE, owns no SNM. Yet the NRC still uses the procedures that began as financial and materials management tools, with modifications, for verification that SNM intended for peaceful use has not been stolen or diverted to unauthorized users.
In support of its policy of nonproliferation of nuclear weapons and the Non-Proliferation Treaty, the U.S. Government has voluntarily entered into an Agreement with the International Atomic Energy Agency (IAEA) to have a national system of accounting for source and special nuclear materials. This information system is called the Nuclear Materials Management and Safeguards System (NMMSS). NMMSS contains current and historical data on inventories and transactions involving source and special nuclear materials within the U.S. and on all exports and imports of that material. NMMSS is jointly funded by DOE and NRC and operated under a contract to DOE.
Material control means the use of control and monitoring measures to prevent or detect loss when it occurs or soon afterward.
Material accounting is defined as the use of statistical and accounting measures to maintain knowledge of the quantities of SNM present in each area of a facility. It includes the use of physical inventories and material balances to verify the presence of material or to detect the loss of material after it occurs, in particular, through theft by one or more insiders.