Daher to apply for NRC transport package certification

Monday, 2 July 2018

Enriched uranium hexafluoride (UF6) is shipped from enrichment plants to fuel fabricators in so-called type 30B cylinders, transported within a protective structural packaging - or PSP - which provides the material with further protection against impacts, fires, immersion in water and also against any criticality incident.

The transport of nuclear material is a vital link in the nuclear fuel supply chain and is regulated according to standards set by the International Atomic Energy Agency (IAEA). To ensure the safety of workers and the general public, nuclear materials must be transported in appropriate packaging, with shielding to reduce potential radiation exposure. Packages containing UF6 must also be able to withstand further pressure tests, a free drop test, and a thermal test at a temperature of 800°C for 30 minutes.

Speaking at the World Nuclear Fuel Cycle conference in Madrid earlier this year, Franz Hilbert, COO of Daher Nuclear Technologies GmbH, said the designs of the 30B cylinder - and many of the PSPs currently in use - have been in use for many decades. The DN30 aims to be a "new and reliable" solution, which will also offer the ability to package enriched reprocessed uranium, which includes small amounts of uranium-232. This isotope decays to thorium-228 leading to increased dose rates. Once loaded with RepU, packages require type IF or B(U)F approvals under the IAEA regulations. The DN30 meets these requirements.

The DN30 PSP meets the requirements for the transport of fissile materials under three of the IAEA's five classification types: AF, for enriched uranium product with enrichment up to 5%, and IF and B(U)F. As well as enriched uranium up to 5%, IF and B(U)F also cover concentrations of uranium-232 up to 0.02 micrograms per gram U without time restrictions, or up to 0.05 micrograms per gU with time restrictions on how soon the material is allowed to remain in the PSP.

The B(U)F classification also allows for the presence of up to 11.4 kg UF6 of 'heels', which is a standout feature of the DN30 design. Heels are the small amounts of residual material that may be left behind in a previously used cylinder, and contain a higher concentration of impurities and decay products, leading to higher dose rates.

The DN30 PSP's safety features include a valve protecting device, to comply with new regulations requiring that neither the valve nor plug touch any part of package after testing and a new thermal protection system - an intermittent layer of material which expands when exposed to heat of 150 degrees Celsius - which will close cracks if damage occurs. The DN30 is fitted with a rotation prevention device, which prevents the cylinder inside the package from rotating onto its side during a drop, and its closure system is protected with coded bolts and a safety lock. A high security seal can also be applied.

The DN30's feet are compatible with other PSP designs so will fit onto existing transport or storage racks, and its lifting lugs are also the same as other designs so no change to handling procedures is required for the new package.

Licensing and supply

Daher lodged its initial application for a certificate of package approval from French regulators the Autorité de Sûreté Nucléaire (ASN) and the Institut de Radioprotection et Securité Nucléaire (IRSN), submitting its full Package Design Safety Report (PDSR) in 2016. This included the results of drop testing and thermal testing of the DN30 carried out at the German Federal Institute for Material Research and Testing (BAM). These included fire tests of packages that were "pre-damaged" by drop testing. No leakages were observed.

Daher expects to receive a certificate of package approval from French regulators before year-end and will then apply to have the certificate validated in other countries which have enrichment or fuel fabrication facilities, including Belgium, Germany, the Netherlands, Russia, Sweden and the UK.

The company intends to apply to the US Department of Transport for a licence based on the French certificate, but this will cover import and export only. It also intends to apply for full US certification for domestic transport within the USA. An application is expected to be submitted to the US Nuclear Regulatory Commission before the end of July, Hilbert told World Nuclear News.

The DN30 will be manufactured in Germany, where preparations are already under way. Procurement of material is scheduled to begin in the third quarter of this year, with the intention that the first packages will be ready as soon as the licence is available.