German company IG Farben in order to gain access to this process. By 1945, IG Farben had become a majority shareholder in Norsk Hydro. The plant at Herøya was a direct result of no longer being dependent on immediate proximity to the power sources. This provided the advantage of being able to have the plants and the shipping port in the same location, as was the case with the Herøya plant. Heavy water production at Rjukan The Rjukan plant was the only location in Europe which produced heavy water, a component the Allied powers in World War II feared would be used as part of the German atomic bomb project. At the time, German industrial conglomerate I.G. Farben owned stock in Norsk Hydro, which then produced less than of heavy water per month, and the company was approached to increase its deuterium output to at least per month. Although Hydro's management had previously refused to supply the heavy water, the company relinquished its resistance and agreed to supply 1.5 tons of the material per year upon Norway's surrender to Nazi Germany. Consequently, Norsk Hydro's facilities were the target of several commando and air raids and a sabotage raid which eventually resulted in the plant's destruction and later reconstruction. First metal production The first steps towards light metal production came in 1940 when Hydro started construction of a magnesium carbonate plant at Herøya, but the German invasion of Norway stopped the plans. In 1941 the Oslo Consortium (Norwegian: Oslo-konsortiet) invested money equivalent to year 2014 Norwegian kroner 172 million. (The consortium included Thomas Fearnley, Orkla, Fred Olsen, Storebrand, Jens P. Heyerdahl, Klaveness & Co, Christopher Kahrs Kielland.) Collaboration with the Nazi-German regime, did not result in any company employees being convicted (for collaboration) after the war. During the Second World War Norsk Hydro collaborated with IG Farben and Nordische Aluminium Aktiengesellschaft (Nordag) in building new aluminium and magnesium plants in support of the German war effort. The construction was however ended on July 24, 1943 when an allied bombardment completely destroyed the facilities, killing 55 construction workers. As Germany's defeat became more likely, Norsk Hydro started to tone down its collaborative relations with the occupier. In 1946 the Årdal aluminium plant was opened, operated by the state owned company Årdal og Sunndal Verk. In a merger Hydro acquired this company in 1986, in essence establishing the light metal division Hydro Aluminium.