The Munich-based industrial giant said late Tuesday it had signed a memorandum of understanding to form a joint venture with Russian firm Rosatom that they hope will become the "world market leader" in nuclear technology.
The joint company, in which state-run Rosatom will hold 50 percent plus one share, will be active along the entire nuclear chain from making the fuel, building atomic power stations to decommissioning of old plants.
The tie-up ruffled feathers in France where Siemens recently ended a cooperation agreement with French state-controlled Areva. Their joint company, Areva NP, is to be wound up by January 30, 2012.
Areva, which now faces a serious rival in the shape of the Siemens-Rosatom joint venture, said the draft agreement amounted to an "unilateral breach of contractual obligations."
France produces around 80 percent of its electricity from nuclear power and President Nicolas Sarkozy has been active in trumpeting his country's know-how to win French companies new business abroad.
The deal comes amid growing interest in nuclear power around the world, sparked by a desire by governments to reduce their dependence on oil, gas and coal.
Energy Prices hit record highs in 2008, squeezing consumers and firms and stoking inflation, while there are also worries about the long-term reliability of oil and gas supplies from Russia and the Middle East.
Concerns about the impact of fossil fuels on climate change have also forced a fresh look at nuclear power. According to Siemens, by 2030 there will be around 400 new nuclear power plants around the world, representing €1 trillion ($1.25 trillion) in investment.
"There are currently 32 nuclear power stations being built around the world, 70 projects at an advanced state and up to 230 could be launched in the coming years," Dieter Marx, secretary general of nuclear lobby group Deutsche Atomforum, told AFP.
In Europe, Britain approved the construction of a new generation of nuclear plants last January and the Italian government has staged a U-turn on its decision to abandon atomic energy.
German firms have not been slow to jump on board, with the two biggest energy groups, EON and RWE, announcing in January they were teaming up to get a piece of the British nuclear pie. But in Germany itself, Europe's most populous country, nuclear power remains taboo.
Former chancellor Gerhard Schröder's government decided to mothball the last of Germany's 17 nuclear reactors - which produce a quarter of Germany's power - by about 2020.
Polls show that a majority of Germans also remain opposed to nuclear power and believe the technology remains highly dangerous because of potential accidents and terrorist attacks.
Shipments of radioactive waste to the country's storage site at Gorleben regularly spark angry protests, with demonstrators chaining themselves to trains and blocking access to the plant en masse.
But nuclear is not dead and buried yet, with support among Chancellor Angela Merkel's conservatives for a re-think growing.
The conservatives, who argue that abandoning nuclear power undermines the goal of cutting greenhouse gases, want to look at extending the life of some nuclear power stations.
According to the Financial Times Deutschland daily on Wednesday, Siemens's new tie-up in Russia has Merkel's full backing.
"Political pressure is growing in Germany," Dieter Marx said. "When the government decided to abandon nuclear, they claimed that other industrial countries would follow suit but as it turns out, they are not only practically alone in the world, we are seeing lots of countries in Europe taking the opposite decision."
The issue is expected to rear its head in German elections in September, when Merkel's conservatives hope to be able to ditch their anti-nuclear Social Democrat coalition partners.