There are major issues of safety in relation to the transportation of uranium waste to Russia, including extreme risk from fire hazards and non-compliance with IAEA standards. This is important as Hex is particularly dangerous because as well as being radioactive it reacts with air to produce hydrofluoric acid, a gas which destroys the lungs.

The bulk of uranium exported to Russia is in the form of UF6. While stable and unreactive with oxygen, nitrogen and carbon dioxide it reacts violently with water, including water vapour in the air, forming corrosive hydrogen fluoride (HF) and a uranium-fluoride compound called uranyl fluoride (UO2F2). Because of this instability, DUF6 is stored and transported in containers requiring compliance with IAEA TS-R-1 for conveyance between states.

In addition to leaks through corrosion (in particular at sites in Russia) DUF6 containers are at most risk from external fire, and as with other nuclear transport’s there are major issues of safety involved. Analysis of the time to failure under the IAEA TS-R-1 thermal test conditions (800oC for 30 minutes) of the most common type of DUF6 container (48G) predicts rupture to occur 12 minutes 20 seconds from the onset of fire.(1) At the point of rupture, the UF6 liquid and vapour temperatures have reached 127oC and 356oC respectively, giving an airborne release of about 1,750kg of the 12,700 kg total DUF6 contents. So in the case of DUF6 containers, the shipments do not meet even IAEA standards. To make matters worse average ship fires burn in excess of 21 hours and in excess of 1000 degrees.

UF6 container (type 48y) in port of Le Havre en route to Russia

The fire hazard could be even greater, as disclosed by French government agency Institut de Protection et de Sreté Nucléaire (IPSN) in Paris, which advises the French government on nuclear safety. In a 2000 study(2) flasks were baked in an oven and running computer simulations if the hex container most widely used, a type 48Y, would survive the kind of fire that could erupt after an accident. Their conclusion was, "Rupture of the 48Y container in a fire seems likely and its resistance to fire should be improved to guarantee safety," they said.

"Large quantities of uranium hexafluoride might be released in a transport accident involving a fire," the scientists said.

The IPSN study was launched in the wake of the sinking of the French cargo ship, Mont Louis, on August 25 1984 after a collision with a ferry in the English Channel. It went down off Ostend, Belgium, with 350 tonnes of hex destined for Russia on board.

Compliance and protection against prolonged fire engulfment is less obvious and seems to be under continuing review by the IAEA HEXT Working Group. The claim is that the existing container designs have survival times of 25 to 35 minutes for an unprotected container so that, to meet the TS-R-1 30 minute compliance ‘only a small adjustment’ to the container’s fire resistance is required, although this is contrary to the previously cited US analysis.

The IAEA Co-ordinated Research Programme (CRP) has evaluated the performance of UF6 containers subject to fire conditions and, although actual testing with a UF6 filled container is not mandatory being considered not to be ‘a realistic option’ (and has never been undertaken), the CRP cannot agree (2003-4) on a general computer/calculation model to predict container performance under fire engulfment. Present ‘solutions’ to the doubts over thermal performance include thermal over-packs, and fire shields for the transport vehicles. Once that the container has finished with its transportation role there is not, apparently, any internationally binding requirements relating to the adequacy of inspection and upkeep for the storage role. Only when the container is reused for transportation of UF6 will compliance with IAEA TS-R-1 be required.

The conclusion is that there are major issues of compliance with existing IAEA standards (which themselves are not robust in terms of real ship fire conditions).

Notes:
1. Uranium Hexafluoride Tailings, Large&Associates, for Greenpeace International November 3rd 2005
2. A study conducted in 2000 by French nuclear safety agency, IPSN, based upon computer simulations found that UF6 containers were breached within in 175 Citation: Int. J. Radioact. Mat. Transp. 11(4), pp 279-294 (2000) “Simulation of the Thermal Behaviour of UF6 Containment Packages in Fires, J.C. Ferreri, A. Clausse and F. Basombrio.