Rjukan is most known today for its connection to the development of heavy water at its Vemork plant. I won’t go into too much detail about what happened here during the war; that’s for a separate article once I visit the Industrial Workers Museum.

As we know, between 1907 and 1911 Norsk Hydro built the plant at Vemork. In 1934, they built an adjacent hydrogen plant. Certainly, a by-product of hydrogen projection via water electrolysis is heavy water.

The Nobel Prize winner Odd Hassel told Norsk Hydro they were producing heavy water; they didn’t know before then!

What is Heavy Water?

Heavy water is a form of water that contains only deuterium (heavy hydrogen), rather than common hydrogen. Moreover, the presence of the heavier hydrogen isotope gives the water different nuclear properties. Water has two hydrogen atoms and one oxygen atom. Heavy water has deuterium instead of hydrogen. Furthermore, regular hydrogen has one proton in its nucleus, while heavy water has one proton and one neutron. The increase of mass gives it physical and chemical properties when compared to normal water. It looks like water, but is 10% heavier.

One purpose of heavy water is using it in nuclear reactors. Heavy water slows the neutrons so they can react with uranium in the reactor. One use of heavy water is developing nuclear weapons.

World War II

This is where we get into World War II. During the war, the Germans took over Norsk Hydro. German scientists discovered that uranium is useful for energy and weapons. Also, heavy water acts as a moderator in a reactor and contributes to the refining of uranium, suitable for atomic bombs. If you aren’t a science person, all that matters is that the Germans were developing heavy water at Vemork in Norway for their atomic bomb.

Norwegian resistance members discovered this, and immediately set about sabotaging their operations. They launched several attacks on the facility. The most famous is the sabotage operation in winter 1943. While they were able to damage the facility, production soon continued. However, the Norwegians were able to destroy the boats leaving Rjukan via Mael and thus halt the Germans plans to export the heavy water back to Germany. The ship that carried the heavy water is under the lake near Mael.

The heavy water facility was blown up in 1977. In 2017, the secret cellar used by the Germans was discovered. It is currently being preserved so visitors can see the remains.

Today Vemork power station is the Norwegian Industrial Workers’ Museum. The history of Rjukan and the industrial worker is told, in addition to the history of war and sabotage associated with the place.