The British government on Tuesday threw its weight behind nuclear power, saying it would back a major new generating plant on the coast of the North Sea northeast of London. The government said it would invest £700 million ($842 million) for a 50 percent stake in Sizewell C. EDF, the French state utility, which will construct the plant, will hold the rest. The deal squeezes out a Chinese state-owned company, China General Nuclear, which had owned 20 percent of the project. CGN received an undisclosed sum for its share, reflecting…