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A former Fukushima Daiichi reactor designer turned whistle blower today said the crippled plant's reactor No 4 had been relying on flawed steel to hold radiation in its core, and that he himself helped hide the defect when the reactor - which he called a "time bomb" - was built four decades ago. Charles Digges, 24/03-2011 Three technicians meanwhile were rushed to hospital after receiving severe radiation burns, triggering a second evacuation of workers in as many days, as anxiety over the safety of Tokyo's tap water persisted. Official readings indicated that radiation levels in the metropolis's water had returned to "normal," but that readings were coming back high for tap water in two neighboring prefectures, Chiba and Saitama.

The fate of Japan's Fukushima prefecture, where hundreds of thousands of people have been evacuated, appears to lie somewhere between the outcomes at Three Mile Island and Chernobyl. There were no evacuations during the Three Mile Island accident, which released about 50,000 curies of radioactive gas. Today you can picnic outside the gates of the plant without fear of lingering radiation. Chernobyl, by comparison, was a nuclear volcano, churning millions of curies of radiation into the sky. Twenty-five years later, only official workers are allowed within 30 kilometers of the entombed reactor at Chernobyl, and radiation levels inside the zone exceed normal background radiation by factors of 100.

The Royal Navy is to drop a dangerous type of reactor used in its existing nuclear submarines because it fails to meet modern safety standards, defence ministers have disclosed. A safer type of reactor is expected to be used in the submarines that will replace the Trident fleet, as the existing design shares very similar features to the nuclear reactors involved in the Fukushima Daiichi disaster in Japan. Liam Fox, the defence secretary, told MPs there was a "very clear-cut" case to use the new type of reactor because it has "improved nuclear safety" and would give "a better safety outlook". A heavily censored Ministry of Defence report disclosed earlier this month by the Guardian and Channel 4 News said the current reactors are "potentially vulnerable" to fatal accidents, which could cause "multiple fatalities" among submarine crews.

The earthquake-tsunami crisis caused up to $310 billion in economic cost in the seven worst-hit prefectures, a preliminary Japanese government estimate said. The government Wednesday also warned about the disaster's negative impact on the country's export and industrial output recovery, the Kyodo news service reported. The economic loss estimate ranged from 16 trillion yen or $198 billion to 25 trillion yen or about $310 billion, resulting from the destruction of social infrastructure, housing and corporate facilities in the regions worst-hit by the March 11 disaster in northeast Japan, the government said.

Edano also said an exclusion zone around the plant did not need to be expanded and he urged Tokyo residents not to hoard bottled water, a plea that fell on deaf ears with many shops quickly selling out of supplies. "If this were temporary, I wouldn't be so worried. If this is a long term, I think we have a lot to worry about," said Riku Kato, father of a one-year-old baby. Physicians for Social Responsibility, a U.S. anti-nuclear group, disputed the food safety assurances and called for a more strict ban on sales of exposed food. "There is no safe level of radionuclide exposure, whether from food, water or other sources. Period," said physician Jeff Patterson, a former president of the group.

The release of two types of radioactive particles in the first 3-4 days of Japan's nuclear crisis is estimated to have reached 20-50 percent of the amounts from Chernobyl in 10 days, an Austrian expert said on Wednesday. The calculations published by Austria's Central Institute for Meteorology and Geodynamics may add to growing concern in Japan and elsewhere over the contamination of food products such as milk and vegetables in areas near the Japanese reactor site. On Tuesday, France's IRSN radiation protection and nuclear safety institute estimated that leaks of radiation from the Fukushima plant crippled by the March 11 earthquake and tsunami represented about 10 percent of those from Chernobyl, the world's worst nuclear disaster, in 1986. Astrid Liland, of the Norwegian Radiation Protection Authority, said there was a peak in radiation in Japan a couple of days ago and levels had since decreased.

One of the reactors in the crippled Fukushima nuclear plant may have been relying on flawed steel to hold the radiation in its core, according to an engineer who helped build its containment vessel four decades ago. Mitsuhiko Tanaka says he helped conceal a manufacturing defect in the $250 million steel vessel installed at the Fukushima Dai-Ichi No. 4 reactor while working for a unit of Hitachi Ltd. (6501) in 1974. The reactor, which Tanaka has called a "time bomb," was shut for maintenance when the March 11 earthquake triggered a 7-meter (23-foot) tsunami that disabled cooling systems at the plant, leading to explosions and radiation leaks.

The Japanese electricians who bravely strung wires this week to all six reactor buildings at a stricken nuclear power plant succeeded despite waves of heat and blasts of radioactive steam. The restoration of electricity at the plant, the Fukushima Daiichi Nuclear Power Station, stirred hopes that the crisis was ebbing. But nuclear engineers say some of the most difficult and dangerous tasks are still ahead - and time is not necessarily on the side of the repair teams. The tasks include manually draining hundreds of gallons of radioactive water and venting radioactive gas from the pumps and piping of the emergency cooling systems, which are located diagonally underneath the overheated reactor vessels. The urgency of halting the spread of radioactive contamination from the site was underlined on Wednesday by the health warning that infants should not drink tap water - even in Tokyo, 140 miles southwest of the stricken plant - which raised alarms about extensive contamination.

Radiation at the crippled Fukushima No.2 nuclear reactor was recorded at the highest level since the start of the crisis, Japan's nuclear safety agency said on Wednesday. An agency spokesman said 500 millisieverts per hour of radiation was measured at the No.2 unit on Wednesday. Engineers have been trying to fix the plant's cooling system after restoring lighting on Tuesday.

Health risks of the releases of radioactivity from the Fukushima Daiichi nuclear reactors: Are they a concern for residents of the United States? Prepared by Seth Tuler, Research Fellow, SERI1 March 2011 Earlier this week the Comprehensive Nuclear Test Ban Treaty Organization modeled how the dispersion of radioactive plumes from the Daiichi reactors would reach the west coast of North America.2   Measureable concentrations of radiation from the reactors have been detected in California, as well as the East coast. At the same time, the Chair of the US Nuclear Regulatory Commission said at a White House press briefing that "You just aren't  going to have any radiological material that, by the time it traveled those large distances, could present any risk to the American public."

At Time.com's Curious Capitalist, Michael Schuman calculates that the Tohoku quake could end up being the costliest earthquake ever in dollar terms, not counting the loss of human life. One consulting group estimated that insured property losses from the calamity could reach as high as $35 billion, making it the second-most expensive natural disaster ever, after Hurricane Katrina. And another firm estimated that total losses to home, factories, infrastructure and other property could exceed $100 billion when the final tallies are made. Sobering stuff.

Spinach with radioactive iodine 27 times more than the government-regulated limit was found in the city of Hitachi in Ibaraki Prefecture, more than 100 kilometers south of the crippled Fukushima Daiichi nuclear power plant, but the radiation levels do not affect human health, local authorities said Sunday. The growing public concern over the safety of farm products prompted the government the same day to consider instructing local authorities to halt the shipment of relevant produce within a prefecture if produce made there is found containing radioactive substances at levels exceeding regulation, government sources said. Currently, prefectural governments decide whether to ask municipalities to voluntarily halt shipment of contaminated products. In 1 kilogram of spinach grown in open air in the city, 54,000 becquerels of iodine was detected, exceeding the 2,000 becquerel limit preliminarily set by the government under the food sanitation law, the Ibaraki prefectural government said. The level of cesium in the spinach grown in the city was also higher at 1,931 becquerels, compared to the limit of 500 becquerels.

Radiation 1,600 times higher than normal levels has been detected in an area about 20 kilometers from the crippled Fukushima Daiichi nuclear power plant, International Atomic Energy Agency officials said Monday. Data collected by an IAEA team show that radiation levels of 161 microsievert per hour have been detected in the town of Namie, Fukushima Prefecture, the officials said. The government has set an exclusion zone covering areas within a 20-km radius of the plant and has urged people within 20 to 30 km to stay indoors.

Japan is racing to gain control of the crisis at the Fukushima nuclear power plan. Where does the most detailed data come from? Updated daily The 9.0 magnitude earthquake and following tsunami last week has seen Japan struggle as it battles to control the nuclear meltdown of power plants in the north-east of the country. Fukushima nuclear power plant in particular has been closely scrutinised as reports flow in on the progress of the plant - Japan's nuclear board raised the nuclear alert level from four to five last week and the latest update this afternoon warns of products such as dairy and spinach being restricted for shipping. Explosions and reports of nuclear fuel rods melting at the power plant have meant progress on the situation has been closely followed.

French animation of radiation from Fukushima

Gray smoke rose from two reactor units Monday, temporarily stalling critical work to reconnect power lines and restore cooling systems to stabilize Japan's radiation-leaking nuclear complex. NPR's Richard Harris reported from Tokyo that a fire apparently broke out on the roof of problem-plagued reactor unit No. 3 and burned for several hours, prompting officials to pull back workers at the crippled Fukushima Dai-ichi plant as radiation levels were assessed. There was no immediate spike in radiation at the complex. But Harris said that just as the fire went out, white steam or smoke started coming up from unit 2. "So there's been a little bit of a return to sort of the dramatic state of things that we saw last week although no big explosions, no large amount of radiation released right now," he said.

Around 2,000 anti-nuclear protesters demonstrated in Taiwan on Sunday, demanding an immediate halt to the construction of an atomic power plant. The march comes amid a crisis in Japan after a huge quake on March 11 unleashed a tsunami which crippled an atomic plant 250 kilometres (155 miles) northeast of Tokyo. "In the face of Japan's nuclear crisis... Taiwan should stick to the goal of building itself in a non-nuclear homeland, so that our offspring will be free from any fears of nuclear disasters," Lee Chuo-han, the secretary-general of the Taiwan Environmental Protection Union, told AFP. The flag-waving and chanting protesters demanded that work on the island's fourth nuclear power plant, which is nearly complete, be halted immediately

High resolution satellite image of Fukushima 1

Six workers at the Fukushima nuclear power plant have been exposed to radiation levels beyond the usual legal limit while carrying out emergency operations to make the complex safe. The news came amid reports that radiation from the stricken plant had found its way into the food supply, raising anxiety in a country already struggling to deal with the aftermath of the worst crisis in its postwar history. Meanwhile Switzerland has announced it will move its embassy in Japan to Osaka because of fears radiation levels in Tokyo could increase.

TOKYO (Dow Jones)--Japanese authorities are facing setbacks in their battle to bring the troubled Fukushima Daiichi nuclear power plant in northeastern Japan under control as pressure builds up in one reactor while a target to supply power to another by Sunday may not be met. The Nuclear and Industrial Safety Agency said engineers will open valves inside the container vessel of the No. 3 reactor to alleviate pressure that is building up, a move that could result in the release of radioactive steam. The release of radioactive steam could also affect work being carried out in other parts of the plant, the agency said. However, it said it doesn't expect the government will have to extend the current evacuation zone around the plant as a result of the development.