Repair crews were back at work Tuesday seeking to restore cooling systems at Japan's quake-crippled Fukushima nuclear plant, a day after being evacuated as smoke rose from two of the plant's six reactors.
Officials said electrical power cables have been laid to all six reactors and that they hope to restore some functions at all the reactors within days. However it remains unclear how much damage has been done to the pumps used to keep the reactors' nuclear fuel rods from overheating, or how soon they can be repaired or replaced.
Investors took heart at the improved prospects for averting a catastrophe, driving the benchmark Nikkei stock index up by more than 3 percent in morning trading.
However massive problems remain, with more than 21,000 people dead or missing and 350,000 left homeless by the March 11 earthquake and tsunami. The World Bank has estimated the economic cost of the twin disasters at up to $235 billion, more than twice as much as Japan's 1995 Kobe earthquake.
Japanese officials said white smoke continued to rise at two of the Fukushima plant's reactors Tuesday, but that it was probably water vapor and not an impediment to continued repair work. Defense Minister Toshimi Kitazawa said at a press conference that dark smoke seen rising from one of the reactors on Monday may have been caused by burning oil.
Officials said radiation levels outside the plant had receded since a brief spike on Monday. Constant monitoring is under way after elevated radiation levels have been detected in some food and tap water and in sea water outside the plant.
Japan's nuclear regulatory agency said it hopes to reconnect power to the Number 1 and Number 2 reactor units and to the plant's central control center by the end of Wednesday, and to restore power to the Number 3 and 4 units by the end of Thursday. Officials said Monday that the number 5 and 6 units have already been stabilized.
However the Associated Press quoted plant officials saying critical pumps at the Number 2 unit will need to be replaced. It was not clear how quickly the new pumps can be delivered.
Problems at the plant began when the earthquake and tsunami knocked out the main and auxiliary systems for pumping water into the reactors and adjacent cooling ponds where used fuel rods are stored. If the rods become too hot, they can burn off their outer casings and release dangerous radiation into the air.
Fuel rods in the inner core of two or three of the reactors are believed to have partially melted, but their radiation is contained by heavy concrete chambers. There are fears that the earthquake and several subsequent explosions may have damaged two of the containment chambers as well as one or more of the cooling ponds.
Chief Cabinet Secretary Yukio Edano said Tuesday that officials are closely monitoring radiation levels in sea water near the plant after unusual levels of radioactive iodine and cesium were detected. He said the iodine will quickly lose its radioactivity but that the cesium can build up over time in fish.
On Monday, the government suspended all raw milk shipments from Fukushima prefecture and spinach from four prefectures surrounding the plant after unacceptably high radiation levels were found in the products. Officials said the levels did not pose an immediate health risk.
Residents in one town have also been warned against drinking tap water after elevated radiation levels were found in the water supply.
Officials said electrical power cables have been laid to all six reactors and that they hope to restore some functions at all the reactors within days. However it remains unclear how much damage has been done to the pumps used to keep the reactors' nuclear fuel rods from overheating, or how soon they can be repaired or replaced.
Investors took heart at the improved prospects for averting a catastrophe, driving the benchmark Nikkei stock index up by more than 3 percent in morning trading.
However massive problems remain, with more than 21,000 people dead or missing and 350,000 left homeless by the March 11 earthquake and tsunami. The World Bank has estimated the economic cost of the twin disasters at up to $235 billion, more than twice as much as Japan's 1995 Kobe earthquake.
Japanese officials said white smoke continued to rise at two of the Fukushima plant's reactors Tuesday, but that it was probably water vapor and not an impediment to continued repair work. Defense Minister Toshimi Kitazawa said at a press conference that dark smoke seen rising from one of the reactors on Monday may have been caused by burning oil.
Officials said radiation levels outside the plant had receded since a brief spike on Monday. Constant monitoring is under way after elevated radiation levels have been detected in some food and tap water and in sea water outside the plant.
Japan's nuclear regulatory agency said it hopes to reconnect power to the Number 1 and Number 2 reactor units and to the plant's central control center by the end of Wednesday, and to restore power to the Number 3 and 4 units by the end of Thursday. Officials said Monday that the number 5 and 6 units have already been stabilized.
However the Associated Press quoted plant officials saying critical pumps at the Number 2 unit will need to be replaced. It was not clear how quickly the new pumps can be delivered.
Problems at the plant began when the earthquake and tsunami knocked out the main and auxiliary systems for pumping water into the reactors and adjacent cooling ponds where used fuel rods are stored. If the rods become too hot, they can burn off their outer casings and release dangerous radiation into the air.
Fuel rods in the inner core of two or three of the reactors are believed to have partially melted, but their radiation is contained by heavy concrete chambers. There are fears that the earthquake and several subsequent explosions may have damaged two of the containment chambers as well as one or more of the cooling ponds.
Chief Cabinet Secretary Yukio Edano said Tuesday that officials are closely monitoring radiation levels in sea water near the plant after unusual levels of radioactive iodine and cesium were detected. He said the iodine will quickly lose its radioactivity but that the cesium can build up over time in fish.
On Monday, the government suspended all raw milk shipments from Fukushima prefecture and spinach from four prefectures surrounding the plant after unacceptably high radiation levels were found in the products. Officials said the levels did not pose an immediate health risk.
Residents in one town have also been warned against drinking tap water after elevated radiation levels were found in the water supply.