Energia nuclear(ingles)

The nuclear option
In the world’s debate over how to produce electricity without generating massive quantities of greenhouse gas pollution, the nuclear option is very tempter but has also lots of odds. Using controlled nuclear fission as a source of heat to turn electric turbines generated enormous enthusiasm as from the 1950’s. They had predicted that for the year 2000 more than 1000 nuclearpower plants would be built. But only a tenth of that number were ever built.
“Nuclear power could be one option for reducing carbon emissions. At present, however, this is unlikely: nuclear power faces stagnation and decline.” This means that now the nuclear power is in state of inactivity and the project is falling downwards.
How do the nuclear power plants work?
The fuel used in nucleargeneration is uranium. It is manufactured as small round pellets. A single pellet is less than 3cm long, but produces the energy equivalent to a ton of coal.
In the reaction core, uranium atoms are split in a chain reaction, controlled with rods. The chain reaction releases gamma rays that create high-energy heat (more than 300°C), which heats water. Radioactive hot water is run through pipes pastcold water to create steam that drives a turbine, generating electricity. Waste heat, as steam, is released from the cooling tower.
The arguments in favor for the nuclear option are:
* One pound of uranium contains as much energy as three million pounds of coal.
* Safety in operations of nuclear plants has improved
* Public acceptance of this source has increased
* The expectance oflifetime of older plants has been extended in the licensing process from 40 to an estimated 60 years.
The arguments against nuclear option:
* One of the major problems is an accident at Three Mile Island in Pennsylvania. And seven years later, a far worse accident at Chernobyl were the reactor had melted down. 4.000 people lost their life. It released more than 100 times as much radiationthan the atomic bombs dropped in Nagasaki and Hiroshima. 350.000 were resettled. More than 1.400 miles away Wales suffered harmful effects from the accident. 25 years later it is not safe to eat sheep from some areas of Wales.
* The other major factor is the storage of radioactive waste that remains dangerous for thousands of years.
* The estimated cost of building nuclear power is more than$4 Billion, and construction times doubled as the ones in 1970’s. Nevertheless experience has shown that each year of additional delay in the construction of a nuclear power plant adds another estimated $1 Billion to the cost.
Nuclear power around the world.
There are currently 436 active nuclear reactors around the world, with a capacity to generate approximately 372 gigawatts of electricity.As a group, US nuclear reactors are responsible for almost 31 percent of all nuclear generated electricity in the world.
Only 253 nuclear power reactors were ordered in United States as from 1950 to 2008, 48 percent were canceled, 11 percent were prematurely shut down, 14 percent experienced at least one year of more outage, and 27 percent are operating without having experienced a year plusoutage.
There are more than 50 plants now under construction around the world.
The only company in the world able to build the key portion of a nuclear reactor containment vessel is located in Japan. It is capable of producing no more than four containment vessels in a year.
France’s strong national control and standardization efforts have not shielded its nuclear program from major escalation inreal capital costs and construction times.
It is very risky to place nuclear power plants because it is hugely expensive and at present nuclear power plants come in one size, extra large.

Next generation nuclear power
They would replace the fuel rods, with a “pebble”. The entire pebble is enclosed in a graphite shell that can withstand temperatures of up to 2800°C far higher than the...