Japan's second nuclear reactor in the quake-stricken north experienced serious troubles today after its emergency cooling system failed, triggering a fresh radiation threat. The Fukushima power plant's operator said, pressure was rising inside reactor No. 3 after it lost its cooling system. The development came a day after thousands of people were evacuated from the area after a blast and leakage from the No. 1 reactor at Fukushima, 240 km north of the capital Tokyo. The explosion had blown off the roof and walls around the reactor. According to IAEA, the UN nuclear watchdog agency, an estimated 1 lakh 70 thousand people have been evacuated from the area around the plant. Tokyo Electric Power Company, which runs the power station, notified Japan's nuclear safety agency that the radiation level at the Fukushima No. 1 nuclear power plant had exceeded the legal limit. The nuclear safety agency also said the Tokyo Electric Company acknowledged that the No. 3 reactor of the Fukushima plant had lost its cooling functions is now in the process of releasing radioactive steam. At least 22 people are known to have been exposed to radiation near the plant since yesterday. The authorities said that an emergency had been declared at all the five nuclear reactors as the units had lost cooling ability.The US dispatched plane loads of coolants to the disaster struck nation. In the small town of Minamisanriku alone, about 10,000 people, over half the town's population, remained unaccounted for. Four trains running in a coastal area of Miyagi and Iwate perfectures remained unaccounted for. It is not known how many people were on board the trains that were running on the Pacific coast when the quake hit Northern Japan. Meanwhile, Japan was today shaken by another strong earthquake off its eastern coast, closer to Tokyo. The latest temblor swayed buildings in the capital.The US Geological Survey says, the temblor had a magnitude of 6.2 and struck around 7 this morning IST. It centered about 179 kilometres east of Tokyo, at a depth of 24.5 kilometres. New Delhi has assured Tokyo of all possible help to deal with present disaster caused by Tsunami and Earthquake in Japan. In a letter to his Japanese counterpart, the Prime Minister Dr. Manmohan Singh expressed full solidarity with the government and people of Japan at this hour of crisis. Rescue teams from South Korea, Australia, New Zealand, Singapore and other countries were set to arrive in Japan, after 50 nations offered support following the powerful earthquake.