As many as 15 percent of the 5, 000 previously approved welds in the reactor's auxiliary plumbing, containment dome and spent-fuel cooling systems were X-rayed and found to be defective due to air pockets, poor soldiering and heat damage.
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The power cut last month shut down cooling systems for four spent fuel ponds at reactors 1, 3 and 4, although cooling for the reactors themselves was not affected.
The power cut shut down cooling systems for four spent fuel ponds at reactors 1, 3 and 4 on Monday evening, although cooling to the reactors themselves was not affected.
Hydrogen is building up because, due to low levels of cooling water, fuel rods are partially exposed, causing them to overheat.
This is because most of the area under their floors was taken up by their fuel cells and the massive cooling ducts meant to keep them from overheating.
And so the first order of business -- and this appears to be at least now under control -- is that you keep the water in the spent fuel ponds and you keep cooling the reactors.
It seems too impossible to believe, but according to reports from CNN, Reuters and the AP tonight, the last workers at the Fukushima-Daiichi reactors have been withdrawn from the scene, halting efforts to continue cooling partially melted fuel rods with ocean water.
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In the past month, Fukushima nuclear plant has experienced two power outages that shut down some of its cooling systems for spent fuel ponds.
Their supervisors made the same mistake, so a vital six hours were lost before other methods for cooling the overheating atomic fuel rods were deployed.
Rats were also believed to have caused two power cuts in the last month, shutting down some of the plant's cooling systems for spent fuel pools.
Restarting cooling to the spent fuel pool at reactor 4 had been of particular urgency for Tepco as it had the highest number of fuel assemblies stored there, Kyodo news agency reported.
This is a very difficult situation, and there will be a lot of work continuing as we go forward to deal with continuing to cool the reactors and to provide cooling to the spent fuel pool.
Is it still your assessment that that cooling pond with the spent fuel rods is now empty?
Last month a power cut shut cooling systems for four spent fuel ponds.
In March, a power cut shut cooling systems for four spent fuel ponds.
And as we looked at a lot of the available information, we saw greater challenges, I think, with providing cooling to some of the spent fuel pools that had initially not been as much of an issue.
Cooling problems have resulted in damage to radioactive fuel rods, hydrogen gas explosions, fires and radiation releases.
Cooling systems to the reactors were knocked out, fuel rods overheated, and attempts to release pressure in the chambers led to explosions in the buildings housing the reactors.
The IAEA statement was released hours after Tepco temporarily shut down the cooling system in the second unit's spent fuel pool following the discovery of dead rodents near a transformer.
But the authors are persuasive that some things can be done just as well with less fuel or material: drip irrigation, for example, superwindows, innovative cooling and ventilation systems, integrated fish management, and economic incentives that reward efficiency rather than waste.
The system cooling water which contained spent - but still highly radioactive - nuclear fuel rods failed and it took engineers some 30 hours to repair the damage.
The approximate stand-still of global temperature during 1940-1975 is generally attributed to an approximate balance of aerosol cooling and greenhouse gas warming during a period of rapid growth of fossil fuel use with little control on particulate air pollution, but quantitative interpretation has been impossible because of the absence of adequate aerosol measurements.
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In early April, the cooling system at one of the pools containing spent - but highly radioactive - fuel rods in reactor number three broke down for about three hours.
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