Set in a nuclear sea

 作者:惠镒     |      日期:2019-03-08 09:06:00
By Rob Edwards PLUTONIUM from the Sellafield nuclear plant in northwest England may be polluting seawater on the opposite side of Britain, say Norwegian and German scientists. More than 200 kilograms of plutonium discharged from the Cumbrian nuclear plant between 1960 and 1990 settled in a bank of sediment at the bottom of the Irish Sea. Some scientists have argued that the contamination is likely to stay there, and so does not pose an environmental threat. But a study by the Norwegian Radiation Protection Authority (NRPA) and the Federal German Office for Maritime Shipping and Hydrography suggests that plutonium dissolved from the mud bank has been washed into the North Sea around Scotland, Denmark and Norway. The highest concentrations of plutonium were found off northeast Scotland and the west coast of Denmark. To identify the source of the plutonium, the scientists calculated the ratios of isotopes in the samples. If the pollution had come from nuclear weapons tests the ratio of plutonium-238 to plutonium-239 and 240 should be 0.04. But at many of the 90 sites it was 0.2, which they say points the finger at Sellafield. “If these sediments are confirmed to be the source,” says Justin Brown, a senior scientist from the NRPA,