Radiation, rusty metal seen in tsunami-hit reactor (AP)

TOKYO – Radiation-blurred images taken inside one of Japan's tsunami-hit nuclear reactors Thursday showed steam, unidentified parts and rusty metal surfaces scarred by 10 months' exposure to heat and humidity.

The photos that were the first inside look since the disaster found none of the reactor's melted fuel or its cooling water but confirmed stable temperatures and showed no major damage or ruptures caused by the earthquake last March, said Junichi Matsumoto, spokesman for the plant operator, Tokyo Electric Power Co.

Pipes and grates inside the reactor's containment vessel were seen in some images. Other photos were dark and blurry, resembling abstract paintings. Experts are studying the most obscured photos to identify which reactor parts are there. Radiation was visible as static, or electronic interference with the equipment being used.

The photos also showed the inner wall of the container had been heavily deteriorated by the high temperatures and humidity, Matsumoto said.

TEPCO workers inserted the endoscope — an industrial version of the kind of endoscope doctors use — through a hole in the beaker-shaped container at the Fukushima Dai-ichi plant's No. 2 reactor, hoping the first look inside since the crisis would help them better assess reactor conditions and make repairs.

High temperatures and radiation leaks had prevented the close-up view until now. Results of the 70-minute operation were mixed.

"Given the harsh environment that we had to operate, we did quite well. It's a first step," Matsumoto said. "But we could not spot any signs of fuel, unfortunately."

He said it would take more time and a better technology to get to the melted fuel, most of which has fallen straight down into the area that the endoscope could not reach. TEPCO hopes to use the endoscope to look inside the two other reactors that had meltdowns but that also would require customization of the equipment and further reduction of radiation levels.

The endoscope failed to find the water surface, indicating less-than-expected levels inside the primary containment vessel and questioning the accuracy of water monitors, Matsumoto said.

Radiation-tainted cooling water has been leaking from all three damaged reactors, pooling in massive amounts around the nuclear plant. Determining the No. 2 reactor's water levels could have helped locate cracks or damage causing some of the leaks.

Better assessment will help workers know how best to plug holes and cracks in the containment vessel — a protective chamber outside the core — to contain the radiation leaks and gradually work toward dismantling the reactors.

Three of six reactors at the Fukushima plant melted down after the March 11 earthquake and tsunami knocked out the plant's cooling systems and set off the world's worst nuclear accident since Chernobyl.

TEPCO and nuclear officials have said that melted fuel probably fell to the bottom of the core in each unit, most likely breaching the bottom of the core and falling into the primary containment vessel, some dropping to its concrete floor.

Experts have said those are simulation results and that exact location and condition of the fuel could not be known until they have a first-hand observation inside.

The probe Thursday successfully recorded the temperature inside the containment vessel at 44.7 Celsius (112 F), confirming it stayed below the boiling point and qualifying a "cold shutdown state," the stable condition that the government had declared in December despite skepticism from experts.

The government has said that it would take 40 years until the Fukushima plant is fully decommissioned.

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Study shows deeper meltdown at Japan nuke reactor (AP)

TOKYO – Radioactive debris from melted fuel rods may have seeped deeper into the floor of a Japan's tsunami-hit nuclear reactor than previously thought, to within a foot from breaching the crucial steel barrier, a new simulation showed Wednesday.

The findings will not change the ongoing efforts to stabilize the reactors more than eight months after the Fukushima Dai-ichi plant was disabled, but they harshly depict the meltdowns that occurred and conditions within the reactors, which will be off-limits for years.

The plant operator Tokyo Electric Power Co. said its latest simulation showed fuel at the No. 1 reactor may have eroded part of the primary containment vessel's thick concrete floor. The vessel is a beaker-shaped steel container, set into the floor. A concrete foundation below that is the last manmade barrier before earth.

The fuel came within a foot of the container's steel bottom in the worst-case scenario but has been somewhat cooled, TEPCO's nuclear safety official Yoshihiro Oyama said at a government workshop. He said fuel rods in the No. 1 reactor were the worst damaged because it lost cooling capacity before the other two reactors, leaving its rods dry and overheated for hours before water was pumped in.

The nuclear crisis following the March 11 earthquake and tsunami caused massive radiation leaks and the relocation of some 100,000 people.

Another simulation on the structure released by the government-funded Japan Nuclear Energy Safety Organization, or JNES, said the erosion of the concrete could be deeper and the possibility of structural damage to the reactor's foundation needs to be studied.

JNES official Masanori Naito said the melting fuel rods lost their shape as they collapsed to the bottom of the vessel, then deteriorated into drops when water pumping resumed, and the fuel drops spattered and smashed against the concrete as they fell, Naito said.

TEPCO and government officials are aiming to achieve "cold shutdown" by the end of the year — a first step toward creating a stable enough environment for work to proceed on removing the reactors' nuclear fuel and closing the plant altogether.

The government estimates it will take 30 years or more to safely decommission Fukushima Dai-ichi.

Wednesday's simulations depict what happened early in the crisis and do not mean a recent deterioration of the No. 1 reactor. Oyama said, however, the results are based only on available data and may not match the actual conditions inside the reactors, which cannot be opened for years.

Some experts have raised questions about achieving the "cold shutdown," which means bringing the temperature of the pressure vessel containing healthy fuel rods to way below the benchmark 100 Celsius (212 Fahrenheit). They say the fuel is no longer there and measuring the temperature of empty cores is meaningless, while nobody knows where and how hot the melted fuel really is.

Kiyoharu Abe, a nuclear expert at JNES, said it's too early to make a conclusion and more simulations should be done to get accurate estimates.

"I don't think the simulation today was wrong, but we should look at this from various viewpoints rather than making a conclusion from one simulation," Abe said. "It's just the beginning of a long process."

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'Tornado Alley' reactor not fully twister-proof (AP)

By DINA CAPPIELLO and MATTHEW DALY, Associated Press Dina Cappiello And Matthew Daly, Associated Press – Thu May 26, 6:50 pm ET

WASHINGTON – The closest nuclear power plant to tornado-ravaged Joplin, Mo., was singled out weeks before the storm for being vulnerable to twisters.

Inspections triggered by Japan's nuclear crisis found that some emergency equipment and storage sites at the Wolf Creek nuclear plant in southeastern Kansas might not survive a tornado.

Specifically, plant operators and federal inspectors said Wolf Creek did not secure equipment and vehicles needed to fight fires, retrieve fuel for emergency generators and resupply water to keep nuclear fuel cool as it's being moved.

Despite these findings, the Nuclear Regulatory Commission concluded that the plant met requirements put in place after the Sept. 11 attacks that are designed to keep the nuclear fuel cool and containment structures intact during an emergency.

Wolf Creek Nuclear Operating Corp., which runs the facility about 150 miles northwest of Joplin, said it would take action to correct the problems.

"The issues affected only one of several (emergency) procedures, so we continue to conclude Wolf Creek meets requirements, the same conclusion we've reached for every U.S. plant," said Scott Burnell, a NRC spokesman.

Wolf Creek, until recently, was one of three nuclear plants placed on a federal watch list in March for safety-related issues.

David Lochbaum, a former nuclear plant engineer who now works on nuclear safety for the advocacy group Union of Concerned Scientists, said the equipment that a tornado could disable is the "backup of backups," but that potential should raise concern nonetheless.

"It's kind of nuclear safety 101," Lochbaum said. "It's kind of stupid for it to be there, where it could help with a tornado, and a tornado takes it out."

Already this year, tornadoes have knocked out power to nuclear power plants in Alabama and Virginia, exposing vulnerabilities.

At Browns Ferry in Alabama, storms disabled sirens, meaning that police and emergency personnel would have had to use telephones and loudspeakers in a crisis.

At the Surry Power Station in Virginia, documents obtained by The Associated Press show that a tornado badly damaged a fuel tanker used to refuel a backup generator.

Those instances, along with the situation at Wolf Creek, highlight a larger problem at the nation's 104 nuclear reactors: While reactors and safety systems are designed to withstand a worst-case earthquake, flood, or tornado, that doesn't necessarily mean all emergency equipment or the buildings that house such equipment are disaster proof.

Wolf Creek's location in Tornado Alley means that it was designed to handle the maximum tornadoes possible for the United States, with wind speeds up to 360 miles per hour and a maximum rotational speed of 290 miles per hour.

But its fire truck is parked in a sheet-metal building "not protected from seismic or severe weather events," according to the NRC inspection conducted after the Japanese disaster.

Jenny Hageman, a spokeswoman for the plant, said there are other options besides on-site equipment for dealing with fires.

"We are absolutely protected from a tornado," Hageman said. "Is everything protected from a tornado on this job site? No. But we protect the critical elements."

The NRC's post-Japan inspections found numerous other instances where U.S. nuclear plants kept equipment needed to fight fires or to cope with a loss of electrical power in places that a flood could overwhelm or an earthquake could damage.

What sets Wolf Creek apart is that it is at much greater risk of being struck by a tornado than other plants are from natural disasters.

Since 1985, when the Wolf Creek plant came on line, six tornadoes have touched down in Coffey County, where the plane is located, according to the National Climatic Data Center. All of those twisters were minor, and caused no injuries or deaths.

Over that same time period, the National Weather Service issued 23 tornado warnings in the county.

"Before Joplin, we had a tornado in the county next to us that ripped up the city of Redding," said Coffey County emergency management coordinator Russel Stukey. Stukey expressed skepticism about the NRC's findings, but acknowledged that "a nuclear plant in Kansas should be prepared for a tornado. I wouldn't go as far to say Wolf Creek is not."

Despite the close calls, including the recent series of deadly tornadoes in the South and Midwest, a twister never has struck Wolf Creek, Stukey said.

NRC records show that those nuclear plants hit by a tornado have emerged largely unscathed:

_In June 2010, a tornado ripped off siding off a building housing emergency equipment and knocked out one of two power sources at the Fermi nuclear plant in Michigan. An alert was declared, and the plant was stabilized.

_Tornadoes struck the Quad Cities nuclear power plant in northwestern Illinois in 1990 and 1996. In 1990, the plant's security fence was damaged and the roof of one building blew onto a duct that connects the radioactive waste processing area to a venting stack. No radioactive gas was released. Six years later, a tornado damaged one of the unit's secondary containment structures, leading to an alert and shutdown.

_In 1998, a tornado hit the Davis-Besse plant in Ohio, causing significant damage to electrical distribution systems, sirens and other "unfortified" structures, according to the NRC. There were no adverse effects to public health and safety.

Similar problems occurred more recently at nuclear power plants in Virginia and Alabama in the path of tornadoes. After the twister at the Surry plant damaged a tanker truck used to fuel a backup generator, state officials were unsure whether the generator it supplied was needed to run emergency systems.

The utility called state officials seeking help, and a contractor supplied the plant with a fuel tanker.

"I personally do not want to be that close to disaster again," said Harry Colestock, the director of operations for the Virginia Department of Emergency Management, in an email directing his staff to hold a follow-up meeting with the company, Dominion.

Dominon spokesman Jim Norvelle said an older fuel tanker was at the plant, but utility workers did not believe it could navigate the debris left by the tornado. The company is evaluating how it stores equipment and has agreed to supply a liaison to the state's emergency operations center upon request.

Just over a week later, tornadoes forced the Browns Ferry Nuclear Plant near Athens, Ala., to shut down after severe weather wrecked transmission lines and created problems for a plant in Tennessee.

The storms also disrupted siren systems that alert residents living near nuclear power plants to trouble. The sirens, which are connected to the electrical grid, failed during a blackout. Tennessee Valley Authority officials said they are in the process of adding sirens that have battery backups, meaning they would work even during a power outage.

At one point, only 12 of 100 sirens in the communities surrounding Browns Ferry worked. A similar problem occurred in the region surrounding the Sequoyah Nuclear Plant in Soddy-Daisy, Tenn., which lost 36 of its 108 sirens. If there had been a crisis at either nuclear plant, emergency officials would have driven vehicles with loudspeakers through affected areas to alert residents.

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Associated Press writer Ray Henry in Atlanta contributed to this report.

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Online:

Nuclear Regulatory Commission: www.nrc.gov

Dina Cappiello can be reached at http://twitter.com/dinacappiello

Matthew Daly can be reached at http://twitter.com/MatthewDalyWDC

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Japan's TEPCO admits further reactor meltdowns (AFP)

TOKYO (AFP) – The operator of Japan's tsunami-hit Fukushima nuclear power plant on Tuesday said it believed fuel had partially melted inside three reactors, as long suspected by experts.

Tokyo Electric Power Company (TEPCO) said new readings on water gauges indicated that the fuel had dropped to the bottom of the containment vessels of units two and three, matching its earlier assessment of unit one.

In all three reactors, relatively low temperatures indicated that the fuel was now mostly covered by water that has been pumped into the vessels, meaning there was no immediate threat of an uncontrolled full meltdown.

"It is highly possible that (partial) meltdowns have occurred at reactors two and three," a TEPCO spokesman said as the firm released its latest analysis of data from the plant after the March 11 quake and tsunami.

"Most of the fuel is believed to have fallen to the bottom (of pressure vessels that contain fuel rods) as has happened in reactor one," he said. "They are now being cooled and are in stable conditions."

Japan's March 11 disaster, which left nearly 25,000 people dead or missing, knocked out cooling systems at the Fukushima plant. This led reactors to overheat, triggering the worst nuclear crisis since Chernobyl 25 years ago.

Reactors four, five and six were under maintenance when the quake hit.

TEPCO estimates it will bring all six reactors to safe "cold shutdown", with low pressure and low temperatures, by some time between October and January, although it will take far longer to dismantle the plant.

Emergency crew have sprayed water into the facility since the quake to cool down the reactors and keep fuel rods in containment pools submerged under water, creating tonnes of toxic runoff that has leaked into the Pacific.

This week TEPCO warned that containment vessels for the radioactive water were almost full.

The company is building a new water treatment facility and has also docked a storage tank called the "megafloat" off the site to hold more low-level contaminated water.

An international panel of nuclear experts arrived in Japan this week to assess the accident and is due to report back to the UN's International Atomic Energy Agency in Vienna in late June.

The IAEA announced last week the mission, headed by Mike Weightman, chief inspector of nuclear installations in Britain, would comprise 20 experts from 12 different countries.

Japan has also decided to set up a panel independent of the nuclear industry and bureaucracy, and mostly made up of academics, to look into the causes of the crisis. It is expected to compile a mid-term report in December and a final report by mid-2012.

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