European Union warned on Tuesday it may go ahead and build the world’s first nuclear fusion reactor with whatever partners it can find if there is no global deal to put the project in France at talks in Vienna.European Commission spokesman Fabio Fabbi said EU hoped a deal would be clinched Tuesday to build the International Thermonuclear Experimental Reactor at Cadarache, near Marseille, rather than at a rival site in Japan.‘‘Our priority is to get an agreement with the largest number of participants and if possible with all six partners (the EU, the United States, Russia, China, Japan and South Korea)’’. ‘‘If there is no agreement, we’ll have to think over. how we go ahead with a maximum number of partners who want to participate,’’ he told a news briefing. Nuclear fusion has been touted as a long-term solution to the world’s energy problems. —Reuters