Norwegian Radiation and Nuclear Safety Authority (DSA) is responsible for a nationwide network of 33 stations that continuously measure background radiation levels and has also currently five air filter sample stations located at various sites throughout Norway.
Radnett – automated measuring network
DSA is responsible for a nationwide network of 33 stations that continuously measure background radiation levels. Each station consists of two detectors, one radiation detector and one precipitation detector, in addition to a data communication system which transfers real-time data to DSA.
The network was established in the years following the Chernobyl accident in 1986, and was upgraded to a new and modern network in the period 2006-2008. The purpose of the monitoring network is to provide an early warning if radioactive emissions reach Norway. The measurements from the network will also form an important part of the decision-making base for the Crisis Committee for Nuclear Preparedness in an early phase, once the news of the emissions have reached Norway.
Air filter samplers
The Norwegian Radiation Protection Authority currently has five air filter sample stations located at various sites throughout Norway – three in the northern and two in the southern part of Norway.
The stations are important for surveying airborne radioactivity, and to provide an assessment of the significance and composition of any emissions in the case of incidents. There are similar stations throughout Europe, and inter-state collaboration makes it possible to track any emissions of radioactive substances.
All five air sampling stations use the same method for gathering air samples; a large volume of air is pumped through a fibre glass filter where small particles can’t get through. The filter in the sampling station gathers particles from the air for one week before they are changed and analysed on HPGe detectors in two of DSA`s laboratories (Svanhovd and Østerås).
Some of the stations are also fitted with activated carbon filters for gaseous iodine which is released in case of reactor incidents. These filters are normally changed and analysed on a monthly basis, but more frequently in case of a release, or suspicion of a possible release.
In addition to the automated systems and the air filter sample stations, DSAin collaboration with the Norwegian association of fungi and useful plants gathers different environmental samples on a yearly basis to be analysed at NRPA’s laboratories. Typical samples include fungi, berries, soil, and occasionally bear droppings.
Species of fungi and plants accumulate radioactivity from the surroundings to varying degrees. The accumulation of radioactivity also depends on soil type and weather; hence, it’s important to sample a variety of species every year.
The maximum allowable level of caesium-137 in foodstuff in Norway is 600 Bq/kg, with the exception of reindeer meat where the maximum allowable level is 300 Bq/kg. For baby food the level is 370 Bq/kg regardless of contents.
Norwegian Civil Defence measuring network
The Norwegian Civil Defence has 126 measuring patrols, called Radiac measurement patrols, spread across the whole country.
The patrols can be used for mapping radioactive fallout in their local area, search for radioactive sources, and as support to the emergency agencies. In addition to the preparedness assignments, the patrols carry out measurements 4 times a year to chart the background radiation in Norway on 350 measurement points. Data from these measurements are uploaded to DSA’s servers, and published in a yearly report on radiation in the environment (data from radnett, air filter samples and the Civil Defence network).