By Elaine Lies and Ju-min Park TOKYO (Reuters) – The operator of Japan’s crippled Fukushima nuclear power plant said this month that two storage tanks had leaked about four tonnes of coolant solution used to create an ice wall that prevented groundwater from seeping in. The operator, Tokyo Electric Power Co Holdings (Tepco), said the leak had no impact on the wall or the environment, however. But the incident highlights its struggle to clean up the plant nearly 11 years after a massive earthquake and tsunami set off meltdowns in the worst nuclear disaster since Chernobyl in 1986. It also comes…