Friday, March 18, 2011

Experts had criticised long potential weakness in the design of the reactor

Friday, March 18, 2011

Now, with a mark i containment vessel damaged in the competitive Fukushima Daiichi nuclear plant and other ships it under heavy pressure, which developed in the 1960s General Electric - weaknesses of design - could that development will contribute to disaster.

If the possibility of a reactor cooling is compromised, the ship is containing the last line of Defense. Usually made of steel and concrete, it is intended to prevent - fuel slur for a while - from spewing radiation into the environment, if cooling efforts complete failure.

In some reactors, known as pressurized water reactors the system in a thick steel and cement tomb is sealed. The most nuclear reactors around the world are this type.

But the nature of the containment vessel and pressure fire suppression system in the faulty reactors in the Japanese Fukushima Daiichi plant used physically is less robust, and it long was adopted, has that more prone to error in an emergency than competing designs. In the United States, 23 reactors of 16 sites using the mark i design, including the Oyster Creek plans the Dresden plant near the city of Chicago and the plant of Monticello in Minneapolis in Central New Jersey.

G.e. the mark began, i boiling water reactors in the 1960s, marketing as cheaper and easier to make - part, because they used a relatively smaller and less expensive containment structure.

American regulators began very early weaknesses identify.

1972 Stephen H. recommended Hanau, then a security with the Atomic Energy Commission, official, set the mark i system because it unacceptable security risks. The smaller containment design which more vulnerable was for explosion and rupture of a building in hydrogen - a situation that may have had in the Prefecture Fukushima Daiichi plant was among the concerns cited. In the same year, said Joseph Hendrie, later Chairman of the nuclear regulatory Commission, a successor to the nuclear Commission, was the idea of a ban on such systems was attractive. But the technology adopted so far by the industry and regulatory officials, he said that "reverse this sacred policy, particularly at this time could be the end of nuclear power."

In an E-mail on Tuesday, said David hole tree, Director of the nuclear safety program at the Union of concerned scientists, these words now, ironically seemed the potential global waves from the Japanese accident given.

"she not to ban the end of nuclear power, could be", said Mr hole tree, a nuclear engineer, spent 17 years in nuclear facilities, including three that design uses the g.e.

Ask about the design of its mid-1980s, when Harold Denton, an official with the nuclear regulatory Commission, claims that mark had a 90 percent chance burst 1 reactors should the fuel rods overheat and melt in an accident.

Industry officials denied that assessment, saying that the chance of failure was only about 10 percent.

Michael Tetuan, a spokesman for g.e.'s water and makes sharing, staunchly defended the technology of this week, called it "the industry's workhorse with a proven track record of safety and reliability for more than 40 years."

Mr Tetuan said there are currently 32 mark i boiling water reactors operate safely around the globe. "Never was a violation of a mark i containment system," he said.

Some utilities and system operator threatened to sue g.e. in the late 1980s after providing these corporate documents from the 1975, which proposed that the containment designs either not enough were ship tested or had defects that could compromise security.

The mark have undergone 1 reactors in the United States a large number of changes since the initial concerns have been raised. Among these, according to Mr hole tree, changes to the torus - a water-filled ship were encircling the primary containment vessel, to reduce the pressure of the reactor. In early iterations may steam blast from the primary vessel in the torus under high pressure the ship out of the ground to jump.

At the end of the 1980s all mark were 1 reactors in the United States also with venting systems to help reduce the pressure in an overheating situation retrofitted.

It is not clear exactly what changes were now fail reactors in the Japanese boiling water, but James Klapproth, senior engineer at nuclear for General Electric, Hitachi, said a ventilation system on the Fukushima was plants to relieve pressure.

The special role of the design g.e. in the Prefecture, Fukushima crisis is expected to be a debate, and it is possible that all reactor design could succumb the one-two punch of earthquakes and tsunami such as those that occurred last week in Japan.

Although the g.e. would - appear limited liability in Japan above all, because the regulatory system in this country the most liability attaches to operators - the company's shares fell 31 cents to $19,61 in trading Tuesday.

View the original article here

0 коммент.:

Post a Comment