Today I want to tell you how a small city located north of Berlin became the most radioactive city in Germany! Let’s take a closer look at the history of Oranienburg.
In 1892 a company called Auergesellschaft was founded with its headquarters located in Berlin. It specialised in production and research of thorium gas mantles, radioactivity and rare earth elements including uranium and thorium.
A factory called Auer-Werke located in Oranienburg specialised in thorium-based products like gas mantles or Doramad toothpaste. In 1939, it began production of high purity uranium oxide for Nazi’s nuclear program
Gas mantles used thorium to make them glow brighter. In fact, these mantles delayed the introduction of electric light by a couple of years! Today, such mantles are no longer in produced but they still can be found on the used market and they’re often used as a check source for Geiger counters.
Doramad toothpaste was produced from leftover products after producing thorium mantles. This radioactive toothpaste was supposed to give users many health benefits including stronger teeth and killing bacterias.
At the end of WW2, the US Air Force conducted a massive bombing of Oranienburg in order to prevent Soviets from capturing Nazi’s uranium. As a result, the Auergesellschaft factory was destroyed. This however caused large amounts of radioactive elements to be released into the surrounding area.
Today, 70 years later, there are still many places that show increased levels of radiation. During my trip, I found a few hot spots that measured around 2 uSv/h (beta+gamma).
Gamma spectroscopy of the soil samples collected near Auer-Werke factory revealed that the soil has a rather large amount of thorium 232 and its decay products in it.
As of right now, there are no plans for conducting a clean up of the area. This means that Oranienburg will remain the most radioactive city in Germany for the near future.