Ultrasonic Sealing Techniques: A Possible Solution for Safeguarding the Containment or Storage of Spent Fuel in an Underwater or Dry Environment

Since 1986, JRC-Ispra has devoted efforts to develop and implement special sealing techniques, aimed at the safeguarding of transport/storage spent fuel containers, in particular in view of their probable long-term storage in storage ponds. The technique has been intensively tested on containers called and 1992 at the British BNFL Sellafield plant in the presence of EURATOM and International Atomic Energy Agency (IAEA) inspectors, on occasion of 11 exercises on site and three in Ispra. The solution makes use of a special multielement bottles (MEB) between 1990sealingbolt (SB) which is used to replace one of the standard bolts closing the lid of the container. The special SBs are provided with a unique random signature and an internal breaking device. The first feature allows the verification of the SB's identity and the latter checks its integrity status, both verifications being done at once in a few minutes by means of an ultrasonic reading tool and associated computerized ultrasonic/electronic reading equipment. By using laboratory- PC-based and/or portable equipment, any SB can be read or verified in either dry or underwater conditions. There are several applications under study at JRC-Ispra, each requiring the development of a specific mechanical seal/ item interface, such as MAGNOX reactor calibrated dead weights for underwater spent fuel weighbridge, PWR MOX fresh fuel assemblies or PU02 transport casks.