NUCLEAR waste dumped at sea is expected to leak and be dispersed by currents and tides, despite being sealed in concrete and steel, writes Dick Ahlstrom, Science Editor.
Sea dumping for nuclear and chemical waste was used for many decades with only limited controls, as evidenced by the dumping of munitions, including chemical weapons, in the Beaufort Dyke.
Materials for dumping are usually packed into steel drums and then encased in concrete, but these are broken down over time by salt water and sea movements.
"You don't assume that dumped materials are going to remain isolated," said a source in the Radiological Protection Institute of Ireland. Natural dilution is meant to keep human hazard at a low level, although it is possible to detect leakage when it occurs.
Downing Street has yet to clarify what was dumped. Guardian reports suggest that it included nuclear waste from industry and luminous paint and clock dials.
Luminous paints were used widely for watches, clocks and gauge dials which could glow in the dark. Typically, they used small amounts of the radioactive material, radium, mixed with phosphorescent materials that glow when struck by radioactive particles.
Physicist Dr Peter Mitchell, of University College, Dublin, said there were two points worth high-lighting in relation to dumping in the Beaufort Dyke. "The residual movement of water is from the south to the north, so if there has been any leakage it will sweep the material to the north." And materials dumped in concrete tend to leak only very slowly, so radio-active materials will be dispersed gradually.
Nuclear dumping is now heavily regulated, two key treaties being the Paris Convention and the Oslo Convention. These set out policy on low-level nuclear dumping and are useful forums where concerns and dangers related to nuclear dumping can be discussed.
Any nuclear dumping, however, adds to the burden of radioactive materials already carried by the Irish Sea arising from nuclear reprocessing at Sellafield. Radium is a long-lived material and will remain radioactive for many decades to come.