Year
1999
Abstract
An eddy-current scanning system is being developed to allow the International Atomic Energy Agency (IAEA) to verify the integrity of nuclearmaterial storage containers. Such a system is necessary to detect attempts to remove material from the containers in facilities where continuous surveillance of the containers in not practical. Initial tests have shown that the eddy-current system is also capable of verifying the idntity of each container using the electromagnetic signature of its welds. The DOE-3013 containers proposed for use in some U.S. facilities are made of an austenitic stainless steel allot, which is nonmagnetic in its normal condition. When the material is cold-worked bt forming or by local stresses experienced in welding, it loses its austenitic grain structure and its magntic permebility increses. This change in magnetic permeability can be measured using and eddy-current probe specifically designed for this purpose. Initial tests have shown that variations of magnetic permeability and material conductivity in and around welds can be detected, and from a pattern unique to the container. The changes in conductivity that are present around a mechanicall inserted plug ca also be detected. Further development of the system is currently under way to adapt the system to verifying the integrity and identity of sealable, tamper-indicating enclosures designed to prevent unauthorized access to measurement equipment used to verify international agreements.