Companies Eni SpA Follow WASHINGTON, Nov 20 (Reuters) - The U.S. will lay out the first international strategy for commercializing nuclear fusion power at the upcoming UN climate summit in Dubai, U.S. Special Envoy on Climate Change John Kerry will announce on Monday, two sources familiar with the announcement said. Fusion could have an important advantage over today's nuclear fission plants that split atoms, as it does not produce long-lasting radioactive waste. If deployed successfully, it could one day could provide a cheap source of carbon-free electricity. The former secretary of state will announce his plan to lay out the...