50 years of measuring ambient radiation

Celebration of 50 years of ODL measurements Source: bundesfoto/Laurin Schmid

In the early 1970s, in wake of an impending nuclear weapons attack, Germany began to set up a nationwide network for measuring radioactivity. The first of these measuring devices was installed in 1974 in Holzkirchen in the Bavarian district of Miesbach. Now, 50 years later, 1,700 probes throughout Germany ensure that a possible increase in radioactivity would not go unnoticed. As an early warning system, they make a vital contribution to civil protection.

On 19 and 20 March 2024, the Federal Office for Radiation Protection (BfS) honoured the 50th anniversary of the measuring network with a ceremony and a specialist event in Berlin. Over 150 representatives from the BfS and the Federal Environment Ministry (BMUV) as well as other governmental and non-governmental institutions gathered in Berlin to look at the history of the measuring network and to discuss current challenges.

Paulini: "Civil protection is an ongoing concern"

BfS President Dr Inge Paulin Source: bundesfoto/Laurin Schmid

"I am quite sure that we will need this ODL measuring network for many decades to come", said Inge Paulini, President of the BfS, at the beginning of the event. She also emphasised that this would also require the appropriate equipment and political support and that "civil protection is an ongoing concern."

Jan-Niclas Gesenhues, Parliamentary State Secretary at the BMUV, pointed out that the Russian war of aggression against Ukraine had once again highlighted the potential dangers of nuclear power. Nuclear accident management must be prepared for a wide range of scenarios, including terrorist attacks with "dirty" bombs or even the use of nuclear weapons.

Many of the speakers at the event called for civil defence and nuclear accident management to be more firmly anchored in society and politics. The awareness and knowledge of citizens about how they can protect themselves plays an important role here. According to Leon Eckert, member of the German parliament for the Green party, the turnaround in civil defence has not yet been fully achieved. He could imagine a mandatory emergency response exercise for the population once a year. For example on Civil Protection Day.

Measuring network in Germany

Paulini emphasised that effective civil protection requires intensive cooperation, high-quality data, and open communication. She announced that the measuring network would be further developed and expanded from a technical perspective. "The measuring network should be made more resistant to external influences such as power outages and cyber-attacks. The number of probes in urban centres should also to be increased."

Measurement data available on the Internet

The history of the network goes back a long way. In the early phase of the Cold War, the Federal Republic of Germany had set up warning centres, which were equipped with sirens and bunkers, among other things.

The foundation stone for the new, ambient dose rate (ODL) measuring network was then laid in the 1972 "White Paper on Civil Defence", which stated that NBC measuring stations were to be set up at distances of 12 to 15 km in order to determine the “radiation emitted by radioactive fallout”. The ODL of the gamma radiation is recorded.

Different generations of probes Source: bundesfoto/Laurin Schmid

Fifty years after the first probe was installed, the current measuring network is not quite the same as it was at the beginning. In the early years, all measuring probes had to be dialled by telephone in order to retrieve the data. With a query time of one to two minutes per probe, this easily took seven to eight hours – and that for each of the 10 nodes (i. e. for each warning centre).

The data are now publicly available and can be accessed in real time on the Internet by anyone interested. The seventh generation of probes is now in use. The measuring network has been operated by the BfS since 1997.

Preparation, networking, and new technical aids

In the past 50 years, the probes in the measuring network have recorded elevated values because of an emergency only once. After the Chornobyl nuclear disaster (Russian: Chernobyl) in 1986, the 10 newest probes of the then second generation reported increased radioactivity.

Exhibits from the warning centres Source: bundesfoto/Laurin Schmid

The purpose of the measuring network then began to shift, and the once purely emergency system became a system for the continuous monitoring of both artificial and natural environmental radioactivity. In light of the current Russian war of aggression against Ukraine, both aspects are now relevant.

The second day of the anniversary event in Berlin focused on current challenges for emergency response and the measuring network. These included how to prepare for an emergency, how different players can be networked, and which new technical aids can be used. In addition to the BfS and the BMUV, representatives from the German Armed Forces, the Red Cross, and other institutions as well as the federal states and Switzerland provided insights into their work.