Three different processes
Teaching Guidance for 14-16
What's the difference between radiation, contamination and irradiation?
Wrong Track: Radiation was given out from the ruined reactor at Chernobyl, travelled through the air and got into the grass in North Wales and on the Lakeland hills in Cumbria, so affecting the sheep.
Right Lines: When the explosion occurred at Chernobyl, the resulting fire sent a huge plume of radioactive dust or fallout into the atmosphere over an extensive area. The plume drifted over large parts of the Western Soviet Union and much of Northern Europe, including North Wales and the upland hills of Cumbria. This radioactive dust settled and was ingested by the sheep as they nibbled away at the grass. In this way, accumulations of radioactive material built up in the bodies of the sheep, creating a danger for anybody later eating meat from those sheep.
Teaching about radiation contamination and irradiation
Thinking about the learning
This teaching and learning challenge is related to the previous one. If students are not clear about the difference between radiation and radioactive material, confusion between the processes of radiation contamination and irradiation is likely to follow.
Thinking about the teaching
The difference between radiation contamination and irradiation can be made clear by drawing upon examples such as the Chernobyl accident.
Teacher: The problem with the sheep in Cumbria and North Wales came about due to contamination by radioactive dust carried by the wind at high altitudes. In other words, the radioactive dust, or fallout, fell on the grass, which was then eaten by the sheep. On the other hand, irradiation was a terrible danger for all of those people on the site at Chernobyl who were exposed directly to radiation from the radioactive fuels in the damaged reactor core. The basic point to understand here is that radiation from radioactive materials on the Chernobyl site could not possibly have travelled all the way to the UK. It was the radioactive dust that did the travelling and that contaminated the hillsides.