Using Radiofrequency Identifiers and Optical Time Domain Reflectometers to Verify Fiber Optic Seals

The Euratom Safeguards Directorate (European Commission, DG TREN-I) and the International Atomic Energy Agency (IAEA) have a long-standing desire and policy to pursue substituting on-site inspection efforts with unattended monitoring techniques. This allows for more efficient use of the limited funds. Unattended monitoring requires both containment and surveillance techniques as well as means of measuring the presence or absence of radiation. Various seals are a key component of the safeguards containment systems. The COBRA seals, which are passive fiber optic seals and require no power during their operation, have the seal wire made of a multi-strand plastic fiber optic loop with its ends enclosed in a seal in such a way that ends of the fibers form a unique random pattern of fibers. This unique pattern is recorded at the time of applying the seal as a reference image by shining a light into the ends of the loop and observing the pattern of the fiber ends and recording it. Verification consists of shining a light through the seal wire and comparing the pattern against the reference image and confirming the same pattern. Even though the use of fiber optic seals is well established and works well, the readout and comparison of the reference image against the verification image has always been somewhat time-consuming. The comparison process also requires a fair amount of housekeeping to make sure that the verification image is compared to the right reference image. In this paper, we will discuss two technologies that can be used to perform the seal verification in a different and potentially more efficient manner. The use of Radiofrequency Identification technology (RFIDs) has exploded in recent years and matured to a point where it is very economical to use for many applications. We propose that the seal body be modified to include an RFID, where the reference image (or its equivalent) is stored in the RFID. Secondly, we propose that the equivalent of a reference image and a verification image be obtained with the use of an Optical Time Domain Reflectometer (OTDR). In this paper, we will discuss the advantages and disadvantages of these new technologies.