The shocking discovery was made by chance when an antinuclear campaigner gave a lecture to a science class, and decided to bring one of the old wristwatches from the 1960s that has a so-called radium dial.
Radioactive uranium rocks on display in Austrian schools
Uraninite crystals. Photo: Rob Lavinsky, iRocks.com/Wikimedia
24 October 2016
Austrian education officials have carried out urgent checks in school buildings across the country after one of the stones on display in a classroom turned out to be radioactive uranium.
The numerals on the watch contained radium which helps them to glow in the dark and were created when little was known about the damage caused by radiation.
The antinuclear campaigner had wanted to demonstrate how radioactive the watches were when he turned up at the Missionaries of the Sacred Heart School in the city of Salzburg.
The expert, Thomas Neff, said: "I brought the old watch from the sixties which lights up brightly at night because of the radiation."
He said the watch had been carefully sealed so that nothing could leak out, but despite that the Geiger counter had notched up 1,200 counts per minute, 20 times the normal value.
Yet as he passed near to the collection of rocks, minerals and fossils that were on display in the classroom, Neff's Geiger counter almost "exploded" with over 102,000 counts per minute.
The class was evacuated and experts called in and discovered that one of the rocks was a uranium rock.
If the non-measurable alpha-radiation were to be included, the actual radiation exposure should be at least 250,000 counts per minute, according to local media.
Thomas Neff said: "If you had this rock the whole year in your bag, you would get around 210 millisievert exposure. The exposure to radiation from natural sources is only 2.8 millisievert in a whole year in Austria."
To put this into perspective, in the US the maximum allowable yearly occupational dose is 50 millisievert, while 100 millisievert exposure per year is the lowest yearly dose linked to a likely increase in cancer risk. Yet for severe radiation poisoning, at least 2,000 millisievert would be needed.
The alarm caused checks to be made at other schools in the Salzburg area, and of the 373 notified 11 schools discovered that a total of 38 pieces from their geology collections contained uranium rocks.
Education chiefs said that none of the schools had realised the danger of the radioactive rocks that they had on display.
The radiological laboratory in Austria said: "The radioactive screening and the risk assessment show a basic risk potential in Salzburg schools in case of improper storage."
All of the radioactive rock samples are currently in the radiological laboratory at the University of Graz, with one exception. A fish fossil that also turned out to be radioactive can still be shown in the biology area in a state school after it was deemed to have low enough radioactivity to not pose any risk.
Story courtesy of Central European News.