March 17, 2011 by staff
Japan Reactor, (AFP) – U.S. reactors in Fukushima that are subject to scrutiny, experts point to flaws in their initial design and the absence of a safety device that the nuclear industry is only beginning to address.
Five of the six reactors at Fukushima No. 1 nuclear power plants are said Mark boiling water reactors (BWR) model, developed by General Electric in the 1960s and installed in Japan in the 1970s.
In the 1970s, criticism amplified the Mark ‘s concrete containment shield surrounding the reactor vessel, was vulnerable to an explosion caused by a buildup of hydrogen gas if the reactor overheated.
The original design “does not take into account the dynamic loads that may be experienced with a loss of coolant AA” Dale Bridenbaugh, who resigned as an engineer from GE in 1975 on the alleged problem, told ABC News Wednesday.
Attributed to hydrogen explosions occurred at four units Fukushima, and confinement at the No. 3 and No. 2 reactors were damaged, but apparently not broken.
Partial melting of fuel rods held in reactors 1, 2 and 3, but the information Fukushima – any index – indicates the steel shell surrounding the reactors themselves were not violated, for example French security agencies.
Michael Tetuan, a spokesman for GE Hitachi Nuclear Energy, a unit GE’s current development and sale of nuclear technology said there were 32 Mark 1 installations worldwide in over 23 states- States.
The U.S. Nuclear Regulatory Commission (NRC) has ordered the operators of the United States to modernize Mark plants in the years 1980 to strengthen the containment vessel, “he said.
“We shared with our customers and overseas … but I can not tell you if they do upgrade, “he said.
“We understand that all units of BWR Mark 1 containment in Fukushima Daiichi also addressed these issues and changes implemented in accordance with regulatory requirements in Japan.”
“Two potential security issues have been identified for the GE Mark design,” Viktoria Mitlyng, a spokesman for the NRC said.
First, the ability of the torus – a ring-shaped unit at the base of the reactor – to support a large volume of water vapor that would be diverted to an accident.
The second issue is the device’s ability to evacuate the containment unit to prevent the buildup of hydrogen.
The NRC must be strengthened torus units, vents and hardened – safely remove any accumulation of gas – have been installed as well.
“These changes have been implemented at all plants and GE Mark 1 inspected by the NRC, she said, referring to U.S. plants.
Questions are asked on another aspect of the Mark 1 design, namely the location of cooling tanks holding highly radioactive spent fuel rods.
They are placed under the protection of the containment.
These pools are now the source of intense anxiety in Fukushima, because the pumps for circulation and add water which cools the dive bars failed in the tsunami generated by the earthquake.
“At least two pools of spent fuel at the Fukushima plant caught fire and are emitting radiation in the atmosphere,” said Edwin Lyman, a physicist and expert in the design of nuclear power plants to the Union of Concerned Scientists (UCS), an NGO on nuclear safety.
“(…) The United States has 31 boiling water reactors with fuel pools in a similar situation past that are much denser than those of Fukushima and thus could cause much higher risks if they are damaged, “Lyman said Wednesday at the Senate Environment and Public Works.
He called on U.S. carriers to withdraw some of the stems and place them in dry storage casks to reduce heat load.
[Source: image via THECONSERVATIVETREEHOUSE.FILES.WORDPRESS.COM]
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