Japans crippled nuclear station is yet to stabilize and the reactors must be kept cool to prevent the crisis from deteriorating, the U.S. atomic regulator said, as more aftershocks rocked the country.

Currently the situation is static, Nuclear Regulatory Commission Chairman Gregory Jaczko said at a hearing of the Senate Environment and Public Works Committee yesterday, after Japan raised the severity rating of the accident to the same level as Chernobyl. It is not yet, however, what we believe to be stable and significant additional problems could still occur at the Fukushima Dai-Ichi plant, he said in Washington.

The stricken plant, about 220 kilometers (135 miles) north of Tokyo, is leaking radiation in Japans worst civilian nuclear disaster after a magnitude-9 quake and tsunami on March 11. While Tokyo Electric Power Co.s station has withstood hundreds of aftershocks, efforts to restore cooling systems were hindered this week as temblors forced workers to evacuate temporarily.

Integrity of core facilities of the plant will probably be maintained because of its earthquake-resistant design, said Tomoko Murakami, a nuclear researcher at the Institute of Energy Economics, Japan. Cooling damaged fuel rods is the major task in order to bring the reactors under control.

Jaczko, who said March 16 that extremely high radiation levels from the plant could hinder recovery efforts, didnt elaborate in yesterdays senate testimony as to what problems could arise at Fukushima.

More Aftershocks

The measures being taken to stabilize the reactors are posing new threats as filling reactor containment vessels with water makes them vulnerable to rupturing when aftershocks occur, according to a March 26 internal report prepared by NRC engineers sent to assist the Japanese government.

Tepco, as the utility is called, said a 5.2-magnitude earthquake today didnt damage the plant and recovery work is continuing. Japan was struck by two earthquakes stronger than magnitude 6 yesterday, following a 6.6-magnitude temblor April 11 and a magnitude 7.1 aftershock on April 7.

The March 11 earthquake, the nations strongest on record, and tsunami left about 27,500 dead or missing, according to Japans National Police Agency. The government has estimated the damage at 25 trillion yen ($295 billion). Tepco may face claims of as much as 11 trillion yen, according to one estimate.

Shares Surge

Tepco surged as much as 16 percent to 524 yen after the Yomiuri newspaper reported that the government may ask Japanese utilities to contribute as much as 50 billion yen ($595 million) for each nuclear plant they operate to compensate victims of the accident. The government denied the report.

I havent heard such an idea, Chief Cabinet Secretary Yukio Edano told reporters today in Tokyo. Thats not included among the concrete plans the government is considering.

Tepco traded 14 percent higher at 515 yen at 2:33 p.m. in Tokyo. The stock has slumped 76 percent since the crisis began.

Japans Nuclear and Industrial Safety Agency yesterday raised the rating to 7, the highest on the International Nuclear and Radiological Event Scale. The ranking was increased from 5, the same as the 1979 partial meltdown at Three Mile Island in Pennsylvania. Each level on the scale represents a 10-fold increase in severity.

A 7 rating means there has been a major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures, according to the INES factsheet.

Accident Rating

The assessment is based on the combined severity of the situation at reactor Nos. 1, 2 and 3, according to Hidehiko Nishiyama, deputy director-general of the Nuclear and Industrial Safety Agency, or NISA. The plant has six reactors.

The Fukushima Dai-Ichi station may spew more contamination than Chernobyl before the crisis is contained, operator Tepco said yesterday. The plant has so far released about 10 percent as much radiation as Chernobyl, Japans nuclear safety agency said yesterday.

The leaks wont be stopped in a few days or weeks, Edano said yesterday.

We are trying to resolve the situation as soon as possible and will do our best to cool down the reactors and prevent the spread of radioactive substances, Masataka Shimizu, president of the utility, said in a statement yesterday. Shimizu, who has apologized for the accident, is due to address a news conference at 3 p.m. local time today.

Prime Minister Naoto Kan has asked Tepco to give an assessment of when the company expects to resolve the crisis. An outlook will be presented soon, he said at a news conference in Tokyo yesterday.

Health Risks

Edano said April 11 that residents of some towns beyond the 20-kilometer evacuation zone around the plant will have a month to move to safer areas.

In contrast with Chernobyl, we have been able to avoid direct health risks, Edano said at a public event in Tokyo yesterday. The assessment level of 7 may be the same, but in terms of its shape and content, the process has been different.

The disaster in Ukraine spewed debris as high as 9 kilometers into the air and released radiation 200 times the volume of the combined bombings of Hiroshima and Nagasaki in 1945, according to a 2006 report commissioned by Europes Green Party.

Fewer people have been exposed to high levels of radiation from Fukushima than Chernobyl, said Richard Wakeford, a professor at the Dalton Nuclear Institute at the University of Manchester in the U.K. The important thing is monitoring and protecting people on the ground, Wakeford said by telephone.

Japan is considering raising the severity level of its nuclear crisis to put it on a par with the Chernobyl accident 25 years ago, the worst atomic power disaster in history, Kyodo news agency reported on Tuesday.

The report came as the government expanded an evacuation zone around the crippled Fukushima nuclear plant because of the high levels of accumulated radiation since a 15-meter tsunami ripped through the complex a month ago, causing massive damage to its reactors which engineers are still struggling to control.

The Kyodo report said that the high levels of radiation that have been released by the Fukushima Daiichi plant meant it could raise the severity level from 5 to the highest 7, the same as the 1986 Chernobyl accident.

It said the government's Nuclear Safety Commission had estimated that at one stage the amount of radioactive material released from the reactors in northern Japan had reached 10,000 terabequerels per hour of radioactive iodine 131 for several hours, which would classify the incident as a major accident according to the INES scale.

The International Nuclear and Radiological Event Scale (INES) is published by the International Atomic Energy Agency and ranks nuclear and radiological accidents and incidents by severity from 1 to a maximum of 7.

The Kyodo report did not say when the estimate related to.

Japan had previously assessed the accident at reactors operated by Tokyo Electric Power Co (TEPCO) at level 5, the same level as the Three Mile Island accident in the United States in 1979.

The tsunami was triggered by March 11 9.0 magnitude earthquake, the largest recorded in quake-prone Japan, crippling the reactors' cooling systems.

A spokesman for the Nuclear and Industrial Safety Agency, Japan's nuclear safety watchdog, said on Tuesday that the level of the Fukushima incident was still a 5 and that he was unaware of any move by the government to raise the level.

TEPCO said it had stopped the discharge of low-level radioactive water into the sea that had drawn complaints from neighboring China and South Korea.

It has already pumped 10,400 tonnes of low-level radioactive water into the ocean to free up storage capacity for highly contaminated water from the reactors.

On Monday, shortly after Japan marked one month since the quake, a huge aftershock shook a wide swathe of eastern Japan, killing two people, and knocking out power to 220,000 homes.

It was one of more than 400 aftershocks above a 5 magnitude to have hit the area since March 11.

Because of accumulated radiation contamination, the government is encouraging people to leave certain areas beyond its 20 km (12 mile) exclusion zone around the plant. Thousands of people could be affected by the move.

"These new evacuation plans are meant to ensure safety against risks of living there for half a year or one year," he said. There was no need to evacuate immediately, he added.

TEPCO President Masataka Shimizu visited the area on Monday for the first time the disaster. He had all but vanished from public view apart from a brief apology shortly after the crisis began and has spent some of the time since in hospital.

"I would like to deeply apologize again for causing physical and psychological hardships to people of Fukushima prefecture and near the nuclear plant," said a grim-faced Shimizu.

Dressed in a blue work jacket, he bowed his head for a moment of silence with other TEPCO officials at 2:46 p.m. (1:46 a.m. EST), exactly a calendar month after the earthquake hit.

RADIOACTIVE WATER

Engineers at the plant north of Tokyo said they were no closer to restoring the plant's cooling system, which is critical to bring down the temperature of overheated fuel rods and to bringing the six reactors under control.

In a desperate move to cool the highly radioactive fuel rods, TEPCO has pumped water onto reactors, some of which have experienced partial meltdown.

But the strategy has hindered moves to restore the plant's internal cooling system as engineers have had to focus on how to store 60,000 tonnes of contaminated water.

Engineers are also pumping nitrogen into reactors to counter a build-up of hydrogen and prevent another explosion sending more radiation into the air, but they say the risk of such a dramatic event has lowered significantly since March 11.

The triple disaster is the worst to hit Japan since World War Two, leaving nearly 28,000 dead or missing and rocking the world's third-largest economy.

Concern at the government's struggle to handle the situation is mounting, with Prime Minister Naoto Kan's ruling party suffering embarrassing losses in local elections on Sunday.

Voters vented their anger at the government's handling of the nuclear and humanitarian crisis, with Kan's ruling Democratic Party of Japan losing nearly 70 seats in local elections.

Tokyo Electric Power Co. started Saturday to install enclosing materials in the sea to prevent a further spread of highly radioactive water that seeped from a crisis-hit nuclear power plant, while continuing other efforts to stabilize Japan's worst nuclear crisis.

A Cabinet minister visited the Fukushima Daiichi Nuclear Power Station in Fukushima Prefecture on the same day for the first time since it was rocked by explosions and began emitting radioactive materials shortly after the March 11 quake and tsunami.

During his roughly 45-minute stay, Economy, Trade and Industry Minister Banri Kaieda encouraged workers manning an operational center on the premises and surveyed damaged reactors from inside a bus.

Before his visit to the plant, Kaieda, whose ministry promotes and regulates the nuclear power industry, told reporters the situation was far from being brought under control and expressed his resolve to contain it as soon as possible.

TEPCO, as the company is known, tried to enclose a seawater intake for the No. 2 reactor at the six-reactor plant with seven steel sheets and a ''silt curtain,'' while planning similar curtains at other locations nearby, such as near the intakes for the Nos. 1, 3 and 4 reactors.

The power supplier stopped the leakage of water highly contaminated with radioactive materials from near the intake for the No. 2 reactor on Wednesday. But the company, facing mounting environmental concerns, hopes that the installation will help prevent contaminated water from spreading outside the plant's bay.

The radioactive iodine reading was 63,000 times the legal limit in seawater near the intake a day after contaminated water stopped leaking into the sea.

The utility is also close to finishing the release into the sea of 10,000 tons of water containing relatively low-level radioactive materials. The discharge is aimed at helping resume work to restore the plant's key cooling functions, with priority placed on the No. 2 among the damaged Nos. 1 to 3 reactors.

''We must move highly contaminated water at the No. 2 reactor and elsewhere to a radioactive waste processing facility as soon as possible without leaking it into the sea,'' Kaieda told reporters back in Tokyo after the visit. ''The plant chief said it must be given the priority right now and I agree with him.''

To free up room to pool highly contaminated water that has flooded the No. 2 reactor's turbine building and prevented the stabilization efforts, the company has dumped about 8,300 tons of low-level radioactive water into the sea from the plant's waste processing facility, with an estimated 800 tons of water left to be discharged.

It also pumped out into the sea 1,300 of the 1,500 tons of low-level contaminated groundwater from the Nos. 5 and 6 reactors, expecting to complete the work on Sunday.

For the tainted water filling a tunnel near the No. 2 reactor, the utility will begin channeling it to a 3,000-cubic-meter container inside the turbine building on Sunday to reduce the risk of it seeping into the sea, the government's nuclear safety agency said.

TEPCO also continued to pump nitrogen, an inert gas, into the No. 1 reactor to prevent hydrogen from causing another explosion, while enhancing the purity of the gas to reduce the amount of oxygen mixed in it.

The utility said it will fly a small unmanned helicopter to survey the plant, possibly starting on Sunday depending on the weather, expecting it to capture images of damaged installations at the Nos. 1 to 4 reactors that workers cannot approach due to elevated levels of radiation.

Asked if the working conditions for workers at the plant have improved, Kaieda said in Tokyo that they are hardly enough but have improved ''to a fair degree,'' noting that many people still sleep in the corridors of a two-story antiseismic building on the plant's premises.

In a sign that workers remain worried about high levels of radiation at the plant, companies dispatching workers to the troubled nuclear plant have refused to adopt the government's provisionally raised limit on radiation exposure for nuclear plant workers dealing with a crisis.

The ceiling was lifted from 100 millisieverts to 250 millisieverts in an announcement made on March 15 by the Ministry of Health, Labor and Welfare to enable workers at the plant to engage in longer hours of assignments and to secure more workers, but officials of the companies other than TEPCO say those at the site would not accept the elevated limit.

Before visiting the plant, Kaieda met with Fukushima Gov. Yuhei Sato in the city of Fukushima and inquired about what the localities want the central government to do, partly because the government has directed those living within a 20-kilometer radius of the plant to evacuate to ensure their safety.

On the nation's atomic energy policy, the minister told reporters afterward, ''While I can't say at this point, we need to review standards to enhance safety.''

Also Saturday, Tohoku Electric Power Co. said a human mistake apparently caused the only functioning diesel generator at the Higashidori nuclear power plant in Aomori Prefecture to leak fuel, forcing the utility to stop it at one point following the 7.1-magnitude aftershock late Thursday of the March 11 deadly earthquake.

The operational failure prompted the Nuclear and Industrial Safety Agency earlier in the day to call on the nation's power suppliers to have at least two backup diesel generators on standby even when a reactor is in a stable condition called ''cold shutdown'' or undergoing fuel replacement.

The agency's previous rule that required the suppliers to have just one diesel generator on standby in situations like the cold shutdown was ''not enough, I must say,'' agency spokesman Hidehiko Nishiyama said at a news conference.

Two other diesel generators at the one-reactor Higashidori plant were undergoing maintenance at the time of the aftershock, according to the utility serving northeastern Japan.

The nuclear crisis erupted after last month's 9.0-magnitude earthquake and tsunami knocked out external power supplies and backup generators for cooling systems at the Fukushima Daiichi plant and allowed reactors there to overheat.

The agency's Nishiyama displayed candor about the missteps and failures that precipitated the disaster, saying, ''We had said all along that (nuclear power) was absolutely secure thanks to its multiple layers of protection and five-layer barriers, and I believed this, but we brought this situation onto ourselves.''

''We need to review everything to ensure safety, regardless of precedents,'' he said.

Japan considers wider evacuation zone, but water leak is stopped at reactor site

The Wall Street Journal reports that the Japanese government is considering extending the evacuation zone around the devastated Fukushima nuclear reactor complex.

According to the newspaper, the government is recalculating the risk of radioactivity that continues to be found in areas outside the plant four weeks after Japan's devastating earthquake and tsunami.

Some good news comes via NucNet which reports that workers at the Fukushima nuclear power plant have used 6,000 litres (8 cubic yards) of coagulant to stop a leak from a trench next to the unit 2 inlet point that has been causing highly radioactively contaminated water to flow into the sea since March 29th.

No decision on new evacuation limits yet

The government's top spokesman, Chief Cabinet Secretary Yukio Edano, said April 8 the current 20-kilometer (12-mile) evacuation zone around the Fukushima Daiichi plant may need to be expanded to a larger perimeter. He said the original boundaries were set to protect against short term exposure to radiation, but with continued releases of radioactive material, the government wants a to look at a bigger protection zone.

Edano said the larger zone is expected to prevent cumulative exposure to radiation than a nuclear plant worker is limited to in a year50 millisieverts. A one year dose clearly linked to cancer would be 100 millisieverts. At 400 millisiverts of short-term exposure, the acute symptoms of radiation poisoning can become readily apparent.

"Current evacuation orders apply to areas where people are in danger of having received 50 millisieverts [of cumulative exposure]," Mr. Edano said. "We are now looking into what to do with other areas where, with prolonged exposure, people may receive that

The WSJ also reports that two weeks ago, a Japanese government agency released a computer simulation that showed that in the first 12 days after the tsunami, some areas outside the evacuation zone exceeded Japan's recommended cumulative exposure limits.

It isnt clear whether the government trusts the information sufficiently to make a decision. TECPO has been plagued with reporting errors in radiation measurements.

The government is clear about local contamination problems within a few miles of the Fukushima plant.

"The [hydrogen] explosions sent radioactive materials flying to areas far outside the nuclear complex," Mr. Nishiyama, of Japan's Nuclear and Industrial Safety Agency, said at a news conference. "Radioactive materials, once spread, cannot be put back. The best we can do is to stabilize the damaged reactors and prevent further emissions of radiation."

Workers Use Coagulant To Stop Fukushima-Daiichi Leak

(NucNet): [April 6] Workers at the Fukushima-Daiichi nuclear power plant have used coagulant to stop a leak from a trench next to the unit 2 inlet point that has been causing highly contaminated water to flow into the sea since March 29th.

Tokyo Electric Power Company (Tepco) said that they used liquid tracer to find the source of the leak in the concrete utility trench and then used the coagulant to seal it. The company said the leak had stopped.

Iodine-131 and Caesium-137 were both detected in water sampled in the trench and in the sea near the water discharge. While the radioactive iodine has a half life of eight days, and degrades to background levels in a few weeks, the half life of cesium-137 is about 30 years.

The water leak was discovered on April 2nd when workers detected water releasing a radiation dose rate of more than 1,000 millisieverts per hour in the trench and found a crack about 20 cm wide on the trenchs concrete wall, from where water was thought to be flowing into the sea. Severe radiation poisoning, in some cases, fatalities, occur at 2,000 millisieverts per hour.

Meanwhile, Tepco has begun discharging into the sea low-level radioactive wastewater stored in sub-drain pits at units 5 and 6 and in a reservoir of the central radioactive waste disposal facility.

Tepco plans to discharge approximately 10,000 tonnes of low-level radioactive water and about 1,500 tonnes of the low-level radioactive subsurface water into the sea. [Water weights 8.4 pounds/gallon. A metric tonne is 2,240 pounds. Therefore, 10,000 metric tonnes of water = 22,400,000 pounds / 8.4 equals 2.7 million gallons of radioactive water.

The discharge is necessary because workers need to use the reservoirs for storing highly radioactive water from the unit 2 turbine building, where dangerously high levels of radioactivity in water have been found in the turbine building basement. There is a risk that this radioactive water might also flow into the sea.

Tepco said it is concerned that vital equipment needed to secure the safety of the reactors might be submerged if this water is not drained.

The utility is also monitoring an accumulation of hydrogen gas in the primary containment vessel of unit 1 Measures are being taken to avoid a hydrogen explosion similar to the explosion in the primary containment vessel of unit 2.

Removing Contaminated Water Might Take Another Week, NISA Says

(NucNet): Moving highly radioactive water from a turbine building basement at the Fukushima nuclear power plant might not start for another week, Japans Nuclear and Industrial Safety Agency (NISA) has said.

The water needs to be moved from the turbine building basement to a storage facility. The water has been hampering work to restore the reactor's cooling systems.

NISA said the facility must be checked for cracks that might have been caused by the earthquake, and that this could take up to a week. The agency said the facility was designed to store low-level radioactive water.

The International Atomic Energy Agency said today that overall, the situation at the plant remains very serious although there are early signs of recovery in some functions such as electrical power and instrumentation.

Nitrogen Injection Continues At Unit 1 PCV

(NucNet): The operator of the Fukushima nuclear power plant says it is continuing to inject nitrogen gas into the primary containment vessel (PCV) at unit 1 without any problems.

Injecting nitrogen is intended to displace oxygen inside the PCV, thereby reducing the risk of explosion caused by the combustible combination of hydrogen and oxygen.

Because the containment has already been damaged and pressure inside might drop below atmospheric pressure, there is a risk that outside air containing oxygen could leak into the PCV resulting in the build-up of an explosive hydrogen-oxygen gas mix.

Tepco says it plans to continue the injection for about six days and will also consider taking similar measures at units 2 and 3.

Meltdown no longer seen as likely

The LA Times reported April 8 that Japan's nuclear crisis ebbing. The newspaper indicated that although the situation at the Fukushima nuclear plant is far from stabilized, evidence suggests that a complete meltdown is unlikely.

There is no evidence that overheating during the last month has resulted in any melting of the reactor vessels or their containment structures, Obama administration officials said Thursday.

The assessment, provided to The Times on background, suggests that the plant is unlikely to suffer a complete meltdown.

"We are a long way from a point where anybody would say this is stable," a senior administration official said. "But it is not a runaway. For a long time, we will be at a declining level of risk."

Separately, the La Times reported the staff of the NRC came under heavy questioning April 7 by the Advisory Committee on Reactor Safeguards, which is a panel of experts, academics and nuclear industry officials that provides guidance to the agency.

At a committee meeting, NRC officials were asked about the scientific basis for their agency's advice that Americans evacuate a 50-mile zone around the plant. According to the LA Times, NRC officials said they couldn't provide an explanation and would have to get back to the committee.

credits-www.theenergycollective.com

I will be updating this daily please thumbs up if you like it thanks!!!