THE DN30 OVERPACK – A NEW SOLUTION FOR 30B CYLINDERS - Presentation

The transport of enriched uranium hexafluoride is one of the most essential parts of the nuclear fuel cycle. For these transports 30B cylinders are used worldwide as primary containment of the material. For protection against mechanical and thermal impacts from accident conditions of transport the cylinders are enclosed in Protective Structural Packages (PSPs). Recently, the certificate of package approval USA/4909 expired once and for all reducing the number of usable PSP designs considerably. To ensure reliable transportation and continuous availability of PSPs NCS decided to design, license and manufacture the new DN30 PSP. This PSP is going to be licensed as Type AF/IF/B(U)F for commercial grade and enriched reprocessed Uranium up to an enrichment of 5 wt.%. The DN30 PSP consists of a top and a bottom part which are connected during transport by a robust and easy to handle closure system. The bottom part is equipped with feet for tie-down compatible with existing designs and allowing the transport of four loaded PSPs on a 20’ flatrack as well as loading of the PSPs by removing the top part only. The design pays special attention to the mechanical and thermal properties of the PSP during accident conditions of transport. Extensive FEM calculations and design optimizations by experts from DAHER, the mother company of NCS, have been carried out to ensure that (Regulations para. 677 (b)) “there is no physical contact between the valve and any other component of the packaging other than at its original point of attachment …”. In order to achieve this, the DN30 is equipped with an integrated valve protector (pat. pend.). On the plug side the design guarantees as well the “no contact” condition during accident conditions. To validate the FEM calculations an extensive drop test program is planned, which will be performed early in 2011. The new DN30 overpack is expected ready for service end of 2011.