Radiocesium contamination at a steel plant in Ireland

Radioactive sources have been inadvertently incorporated into consignments of scrap metal in various locations throughout the world. In 1990, a 3.7 GBq 137 Cs source, due for transfer from a Scottish industrial establishment to one in England, was mistakenly included in a scrap consignment destined for Irish Steel, a metal recycling plant in County Cork in the Republic of Ireland. Unaware of the presence of the source, Irish Steel smelted this consignment in the usual manner. This involved separation of some non-ferrous materials which were then exported, in pellet form, To Pasminco Europe (now Britannia Zinc Ltd.) in Avonmouth, U.K. The presence of 137 Cs contamination in these pellets was detected by the U.K. company in the course of a routine radiation survey. Irish Steel carried out extensive decontamination of its plant, placing the contaminated dust in secure storage. The company has equipped itself with radiation detection devices which monitor incoming scrap. Outgoing products and furnace dust are also monitored on a routine basis. While this incident was of negligible radiological significance as far as personnel were concerned, the financial cost to Irish Steel have been substantial. It highlights the need for surveillance, by national competent authorities, of the movement of radioactive sources from production through use to final disposal.