In Japan, more firefighters have been brought in to try to contain a nuclear emergency at the Fukushima nuclear power plant damaged by last week's earthquake and tsunami. The operation was expanded this afternoon when seven fire trucks from the Tokyo fire brigade joined the effort. Authorities at the Fukushima plant, 250 kilometres north-east of Tokyo, have been trying to flood fuel rod storage ponds at the plant after cooling systems were wrecked by last week's twin disasters. The disasters knocked out the plant's reactor cooling systems, sparking a series of explosions and fires.Authorities have since struggled to keep the fuel rods inside reactors and fuel storage containment pools under water. They had some success yesterday with water bombing helicopters and military fire trucks spraying tonnes of water into a damaged reactor building. Fluctuating radiation levels at the complex have also hindered the cooling operation, repeatedly sparking delays. Chief government spokesman Yukio Edano told a news conference that today's radiation levels were at about 100 microsieverts, and that there was no immediate threat to human health. The Chief of the International Atomic Energy Agency Yukiya Amano, arrived in Japan today to check the worsening nuclear crisis in Fukushima. Amano said he would see the situation himself and gather detailed information from the Japanese authorities to learn how the Agency could best help. Meanwhile, Japan's Nuclear and Industrial Safety Agency today said that radiation has seen a steady decline near the damaged Fukushima No.1 nuclear power plant following water-dousing measures taken on Thursday.