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Nuclear Safeguards Education Portal

Cap seal (CAPS)

The metal cap seal has been in service for more than 30 years and is extensively used for sealing material containers, material cabinets and IAEA safeguards equipment. Typically, 20 000 of these metal cap seals are verified each year. The seal is detached in the field and brought to IAEA Headquarters for identification. The primary advantages are that the seals are simple, inexpensive and easily attached or detached by an inspector. Attachment and detachment efficiency is important to limit the radiation exposure of the inspector. Unique identification of each seal is obtained by visually comparing random scratches and solder smears on the inside surface of the metal cap and by comparing the installation and removal images.

Visual inspection of each seal is very labour intensive. Therefore, a modernization programme for the metal seal is currently in progress to maximize counterfeit resistance and to detect breaches of integrity in the wire. Laser surface authentication (LSA) provides an intrinsic material signature in a machine readable form and the consequent ability to verify seals with a higher degree of automation and lower error rates compared with imagery analysis. Once all deployed seals have LSA signatures, the full potential for on-site and/or in situ verification will be realized. The integrity of the wire will be verified by an eddy current probe, which is expected to be deployed for field use in 2012.


(Source: IAEA Safeguards Techniques and Equipment)


(Source: NNSA)