.
From Greenpeace want, first, to express our condolences to the families of the victims of the terrible earthquake suffered by Japan.
We are deeply concerned about the possible consequences of the earthquake and tsunami may have about the safety of nuclear facilities in Japan and other hazardous industries such as oil refineries or chemical plants, and their potential effects on public health and the environment.
The situation in several nuclear plants, particularly in the Fukushima-1, is very worrying. Fourteen nuclear power plants located on the northeast coast of Honshu, the main island of Japan, are closed, probably all of them badly damaged as a result of yesterday's earthquake, of magnitude 8.9 on the Richter scale.
Japanese plants, a country with very strict requirements for resistance to seismic hazards, were designed to withstand earthquakes of maximum intensity 7.5. The strength of that hit Japan yesterday is more than 10 times. At the beginning
the earthquake, those nuclear power plants were taken to stop situation. But, and this is one of the drawbacks of a technology as dangerous as nuclear, risk an accident does not end there, since even with central stop, the nuclear fuel is still active, still nuclear reactions, as well radioactivity, generate much heat. Yet in a position to stop, for further cooling the reactor core, nuclear fuel, for many hours, to avoid a nuclear accident.
The emergency cooling systems of the reactor core can run on electricity. But the earthquake affected the external power supply Fukushima-1 core and 2 (at least these two), leaving them with no power supply, which is called in the jargon of a nuclear black-out station. In that case, should have come into operation immediately the emergency diesel generators of the plant. But these, perhaps because of the earthquake, did not work. So began the countdown.
nuclear fuel, without being actively cooled, began to overheat. The water inside the reactor vessel began to evaporate, the vapor pressure builds up inside the vessel, fuel to stay in the open, without water to cool it. It is the beginning of a LOCA (Loss of Coolant Accident), the loss of coolant accident, the worst that can occur in a nuclear plant. Of those, according to the nuclear industry, can never occur.
first critical hours
The first hours are critical, if not acted upon can be a situation of meltdown (when the metal rods that hold the uranium fuel pellets melt, blend and mix with the hugely radioactive nuclear fuel) and then released in large amounts of radioactive isotopes in the fuel there.
Fukushima-1 is a reactor like Garoña (Burgos), with a lousy support system. In the absence of power external system is a much smaller capacity battery runs own contribution. Thus, for example, try to use the condenser water to cool the core, to buy some time while waiting for diesel generators that were to bring the U.S. military. But this move has a very limited and failed to reverse the situation. The hours passed and the nuclear fuel was running short, at least in part, without water around it: the dreaded meltdown.
With increasing temperature, increased pressure within the vessel. So those responsible for central and, presumably, Nipponese authorities decided to open relief valves and release radioactive steam to the outside atmosphere to lower the pressure, with the idea of \u200b\u200bavoiding a major disaster.
From these facts and no doubt. Until the English Nuclear Safety Council (CSN) is now recognized that nuclear power plant in Fukushima-1 was deliberately forced to escape to the atmosphere of gases from the reactor radioactively contaminated. Radiation levels in the area have risen, according to sources, between 300 and 1,000 times higher than allowed. It was not ordered to evacuate the population, 45,000.
course, any amount of radiation released into the atmosphere threatens the health of people in the area, public health and the environment. What is already clear is that in Fukushima-1 have clearly failed the physical protection measures designed to isolate the radioactivity of the environment.
addition, an explosion on Saturday morning (English hour) in the plant seems to have seriously damaged the structure of secondary containment and there is conflicting information on whether any part of the structure has collapsed. Location
uncontrolled reactor
The situation is critical and not yet controlled, at the time of writing. The final amount of radioactive release will depend, of course, it can stabilize the reactor, and can cool the core. At present, it seems already clear that the accident could be because of the seriousness of what happened at Three Mile Island (USA) in 1979, the second worst in the history of the nuclear industry, only after the catastrophe Chernobyl.
Despite all the uncertainties caused by the lack of information, caused in part by the logical chaos in the country but also for nuclear secrecy of the authorities, we face a scenario in which there may be a huge release of radioactivity of the Fukushima-1 reactor.
the moment, we can not exclude that the situation can move towards a merger total central core, as occurred in Chernobyl. The whole process could go too fast or take several days, depending on the state of the cooling system. The consequences of such an accident would be tremendous, as was found in Chernobyl.
In fact, it seems the Japanese government is expanding the evacuation zone to a diameter of 40 kms. around the Fukushima Daiichi nuclear complex (where the reactor Fukushima-1 and other 5) and has established an exclusion zone of 20 km around the Fukushima-Daini plant (with 4 reactors). This indicates an immediate threat not only around the reactor Fukushima-1, but the situation is not entirely under control in other reactors and could reach more accidents occur there too.
Uncertainty about what is happening in Japan's nuclear plants requires some caution when considering future scenarios. However, one conclusion is clear: nuclear reactors are inherently dangerous. The nuclear industry says that accidents like this can not happen with modern reactors, but now Japan is in the midst of a crisis with potentially devastating consequences because of nuclear energy.
The truly clean energy, renewables, not create problems of national security. And natural disasters do not add one more problem to a population already hard hit by the force of nature. Nuclear power can not be included, as many claim, a clean energy model, safe and sustainable.
* Sara Sawyer Carlos Bravo and energy are responsible for
LCTR Greenpeace. (C & P)
0 comments:
Post a Comment