Japan will pump radioactive water into the sea from a crippled nuclear plant until Sunday, a day later than previously planned. The announcement came a day after China expressed concern at the discharge of contaminated water from the Fukushima Daiichi plant smashed by last month's earthquake, reflecting growing international unease over the month-long nuclear crisis. The Deputy Director-General at Japan's Nuclear and Industrial Safety Agency said, they are working on releasing water and are likely to finish this tomorrow. Plant operator Tokyo Electric Power Co earlier said it expected to stop pumping tainted water into the sea today, but work was interrupted by a powerful aftershock on Thursday. Nuclear reactor maker Toshiba has proposed a 10-year plan to decommission four of the six damaged reactors at the plant. Meanwhile, residents of towns surrounding the crippled plant are regularly returning home, defying health warnings as the crisis drags on. A local newspaper said around 100 people were believed to have stayed inside the 20-kilometre zone, with many more travelling from evacuation centres to their homes to collect valuables or personal effects. Meanwhile, the disaster-hit Sendai Airport, which was closed after being inundated by the March 11 tsunami, will reopen next week.The opening will provide a boost to an area constrained by road closures and the suspension of bullet train services to Sendai.