Thermal Test of the DN30 Package for the Transport of UF6

The DN30 package was developed by DAHER NUCLEAR TECHNOLOGIES GmbH (DAHER NT) for the transport of enriched commercial grade and reprocessed UF6 up to an enrichment of 5 %. It consists of a standard 30B cylinder and the DN30 Protective Structural Packaging (PSP) and shall be licensed as type AF, IF and B(U)F package. The basic design was already presented at PATRAM 2010 [1] and 2013 [2]. This presentation will concentrate on the thermal test simulating ACT. For the thermal test a single DN30 package fully loaded with surrogate UF6 was subjected to twice the drop tests required by the Regulations: first, the regulatory drop test sequence onto the valve corner followed, with the same specimen, by the regulatory drop test sequence onto the plug corner. Results of our computer analyses show an excellent match with the real world drop tests.In the next step, the numerical model for the thermal analysis of ACT was developed based on the damaged DN30 package. The simulation takes into account the regulatory boundary conditions. Furthermore, all mechanical deformations and gaps resulting from the doubled regulatory tests are modelled. In deviation from the package used for the drop tests the model used for the thermal analysis does not contain any surrogate UF6 to minimize thermal capacity and thereby maximize the temperature of the cylinder and its components.The real world thermal test requires a considerable amount of preparation to comply with the requirements of the Regulations. First, the deformations of the prototype used for the drop test, especially the gaps between upper and lower shell, were documented. Then, the DN30 PSP was opened and the 30B cylinder filled with surrogate material was replaced with an empty 30B cylinder. A tailor made heating blanket was manufactured to heat up the specimen to the initial temperatures resulting from NCT and the surface of the specimen was painted to ensure the “sooty” surface. Last but not least, the environmental conditions, especially the ambient temperature and missing insolation during the cooling phase, had to be taken into account by adjusting the exposure period. The thermal test showed that polyurethane foams produce a huge amount of decomposition gases which could flow into the cavity of the PSP and result in an additional heat source for the 30B cylinder and its components. The admissible temperature of the sealing of the valve and plug against the cylinder could be exceeded considerably. DAHER NT improved the design of the DN30 package by adding an additional layer of thermal protection between DN30 PSP and 30B cylinder consisting of intumescent material. Preliminary tests show a dramatic improvement of the thermal protection properties of the DN30 PSP. The regulatory thermal test will be performed early September and the results will be presented at PATRAM 2016.