Japan nuclear crises and developments

Japan nuclear crises and latest developments

Tokyo Electric  lay out plan for its  reactors

The Tokyo Electric power company laid out an ambitious plan on Sunday  for bringing the reactor at its hobbled Fukushima Daiichi nuclear power plant into stable state known as cold shut down within next nine months  and trying to reduce the level of radio-active materials being released in the mean time.

The blue for action represents Tokyo Electrics most concrete time liable yet for controlling  the reactors and improving safety at the plant, which was damaged by massive  earthquake and tsunami six weeks ago.
The first part of its plan, expected to take three months, would include building new cooling systems, critical to preventing catastrophic releases of radio-active materials. Then company hopes to covered three badly damaged reactor buildings and install filters to reduce contamination being released into air.

By announcing the construction of new cooling systems the company implicitly acknowledged what out side experts had been warning for weeks, that the company earlier plan to repair to existing cooling system was unlikely work because the equipment was too badly damaged. The change in approach means that  the country must resign itself to several more months of radio active emission- into air and possibly into Pacific-even though the appeals to be less volatile than it was.

For weeks workers have been consumed with reacting to cascade of problems created not only original disasters but also by make shift fixes for bring the plant under control. By making its announcement on Sunday Tokyo Electric was trying to show that conditions had apparently improved enough in recent days that it was now able to turn some of its attention for planning for future.

“The  company has been doing its utmost to prevent a worsening situation “  Tokyo Electric chair man, Tsunehisa  Katsumata, told news conference.

“We  have put together a road map “ he said adding “ we will put our full efforts into achieving these goals.

On Sunday meanwhile the government  said that  evacuated who were forced to leave their homes near Daiichi plant will be able to start returning in six to  9 months after land is decontaminated. The announcement seems to suggest that few places would be put off limits as they were after more divesting 1986 Chernobyl disaster in Ukraine. But Japanese  official did not  provide specific about low contaminated the land was within several  miles of plant.

In any case the statements were the clearest indication yet that the tens of thousands of people evacuated from the area and living in shelters will not soon be able to return their homes, or  to town  that were destroyed by tsunami. It is also mean that the badly shaken government will have to continue to provide for displaced people even as it struggles to rebuild from quake and stabilize economy.

One government official and nuclear power expert said they  thought Tokyo Electric plan could work, although one said the company should try for cold shut down sooner. A cold shut down means that that the temperature of water in a reactor is below boiling point. Although cooling must continue, the water will not boil away quickly even at atmospheric pressure. Boiling must be avoided because fuel rods have to be kept under water to avoid melt down.

The Japanese government and the company, known as Tepco, have been evenly optimistic in the past. Several weeks ago for instance the company said it hoped that its success in bringing live power lines back to plant would enable workers to quickly restart the existing  cooling systems even though the  equipment would have had survive not just natural disasters, but explosions that rocked the plant in following days.

The announcement on Sunday that new cooling systems would be built was first admission that effects to restart the old system had failed.

Hindeko  Nishiyama, deputy general of nuclear and industrial safety agency, said that  normal cooling systems cannot be revived . In a show of support U.S. Secretary of state  Hillary Rodham Clinton flew to Japan on Sunday from Seoul, South Korea becoming first American official to visit since disaster. She told Japan’s  foreign minister , Takeaki Matsumoto that her visit reflected “ our strong bonds of friendship that go very deep into hearts of people.”

Mrs.Cliton said that the U.S. was “ doing every thing we can to support Japan and we have very good co-operation.” The United  States military has participated in rescue efforts in Japan even after some personnel were exposed to radiation, and Americans quietly helped reopen the airport in Sendai.

While it is difficult to answer some important questions about  the safety of the Fakushima Daiichi plant, in part because it is contaminated now for workers to get close to reactors, the state department said last week that situation at around plant had become less perilous.

Since cooling systems at the plant failed, Tokyo Electric has been cooling the reactors and pools that hold used, but still hot, fuel rods by pouring tons of water on them. But as water boils in the reactor, pressure rises too high to pump in more water, so workers have vent to atmosphere and feed in more water, a procedure known as “feed and bleed”.

That means the plant is consistently spewing radio active materials into air. And although much water that used evaporates, tons of run off have also been created.

Immediately after quake helicopters dropped water on reactor buildings and workers sprayed water into them with fire hoses. The company has since set up large pumping trucks at reactors. At some reactors, the arm of the trucks that deliver the water have been placed over the damaged walls of buildings, enabling to be shot more directly at the reactors and pools and reducing run off.

The long term solution announced Sunday  to build new cooling systems, would eliminate the run off because it would be a closed loop, like systems previously used at the plant. Such systems cool steam comes off reactors, creating water, which is pumped back into reactors. The systems would also stop venting, if they worked correctly.

Until the new  system can be built, Tokyo Electric intends to set up a water processing unit that removes radio-active particles and salt and store it in tanks. But  sign of how much improvisation has gone into plan, company officials said that they would turn  a concrete- walled waste treatment building into large storage tank to hold up to 30,000 tons of contaminated water.

The company plans to place temporary covers three of six reactors buildings at the plant and install air filters to help reduce venting  the company said. Engineers will also start designing structures with concrete roof and sides.

Officials said the temporary covers would made of material similar to tough fabric used to wrap buildings under construction. The company warned that covers could be damaged in a typhoon.

Goshi  Hasono a special ad-visor to prime minister Naoto Kan identified  two risks to company plans :  that the new cooling systems would be too hard  to build quickly and that serious after shock or tsunami could lead a further damage at site before changes could be made.

Hironobu Unesaki,  a professor at research reactor institute at Kyoto university said long term plan seemed mostly sound. But he said company should try to achieve cold shut down of reactors sooner than six to nine months to reduce risk of a large scale radiation release.