Recent aerial air tests detected a higher than average level of radioactivity near the Mühleberg nuclear plant in the canton of Bern, as shown in red in the image below.
The source of the radioactivity was identified as vapour containing the radioactive isotope N-16. N-16 has a half life of around 7 seconds, so it loses its radioactivity quickly. The report described the radiation as consistent with past measurements and something that is expected with boiling water reactors like the one at Mühleberg.
These tests, done every two years by the National Emergency Operations Centre (NEOC), involve flying over Switzerland’s nuclear power stations in a helicopter.
Switched on in 1972, the Mühleberg reactor is Switzerland’s second oldest and is scheduled for decommissioning later this year.
- At a glance – Switzerland’s nuclear power stations (Le News)
- All but one of Switzerland’s five nuclear reactors meet radiation targets (Le News)
In addition to these biennial flights, the NEOC measures radioactivity across 76 stations spread across Switzerland every 10 minutes. If radioactivity exceeds 1,000 nanosievert (nSv) per hour an alarm is automatically triggered.
Typical levels of radioactivity across Switzerland are between 80 and 260 nSv per hour depending on the location. This map shows recent station readings. As a point of comparison, an airport scan in the US must not exceed 250 nSv and a banana contains radioactivity of around 100 nSv, which comes from the potassium in it.
When people hear the word radiation, they often think of atomic energy and nuclear power, however it is all around us in our environment.
Broadly, there are two kinds of radiation: ionizing and non-ionizing. Ionizing radiation, the kind that comes from nuclear power stations, is more harmful because it can knock electrons out of orbit around atoms potentially damaging cells.
However, even without nuclear power stations we are exposed to a certain amount of ionizing radiation from the sun, the earth and things in and around us, something called background radiation.
Exposure from the ground varies across Switzerland. The geology of some regions emits more than others. This map shows how the level is higher in the mountains.
In addition to background radiation a small amount of artificial radiation typically exists. In Switzerland this is only a few percent of the total, mostly from 1986 Chernobyl reactor accident and from nuclear weapons tests in the 1960s.