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Documents released by Tepco Monday showed the isolation condenser— an emergency cooling system installed on Reactor No. 1 before the quake as a final resort in case of a total loss of power—worked only sporadically, if at all. Tepco officials explained that somebody appears to have manually closed the valves on the condenser soon after the March 11 quake—but before the tsunami hit about an hour later—to control the fluctuating pressure inside the reactor. Reopening the valves required battery power, so those valves likely couldn't be opened because the tsunami damaged the backup batteries. If the valves hadn't been shut, things might have turned out differently. Temperatures in the reactor climbed faster than initially expected, causing more and faster damage
Originally posted by Hellhound604
I have designed industrial control systems and avionics systems, and control systems for dam sluices in my past, and one thing ALWAYS taken into account was human stupidity in critical systems, and that if something can go wrong, it will, so you would design a system so that by default, if something goes wrong, i.e. the power fails, or the software crashes (!!!!), that the valves would revert into a fail-safe state, in this case, I would have designed the valves leading to the cooling system to be open by default, so that if something happens, the valves would default to their normal state, which should be open, so that cooling still takes place (the valves to the steam driven emergency cooling systems would be open). It seems either as though somebody is lying about the operation of the systems, or a total d*ckhead designed the system. It would take an operator to deliberately override the system, and that could be construed as sabotage. Normally you would design the system to have f.ex 2 transistors to switch both sides of the relay controlling the valve, so that even if there is a fault, the fail-safe cannot fail.
Just my 2 words.
Wednesday, May. 18, 2011
PM: Japan's nuke regulators need more independence
By MARI YAMAGUCHI - Associated Press
TOKYO — Japan's prime minister acknowledged Wednesday that the recent nuclear accident underscored that his country's nuclear regulators need more independence from the industry to ensure safety.
In Japan, a single ministry is responsible for both promoting nuclear energy and overseeing its safety, unlike most other nuclear power-producing nations that separate the two functions.
"Entities that promote and check nuclear energy belong to the same government institution, which raises a question of independence," Prime Minister Naoto Kan told a news conference where he also promised a thorough review of the nuclear power industry and its regulators.
"We don't necessarily have a sturdy structure in this regard," he said.
* JAPAN NEWS
* MAY 18, 2011, 3:45 A.M. ET
Fukushima Daiichi Diary: Other Problems
By PHRED DVORAK And YUKA HAYASHI
A Wall Street Journal examination of the first 24 hours after the Fukushima Daiichi accident shows that disaster piled on disaster, worsening the nuclear crisis faster than anyone had initially thought could happen. Here's a more detailed look at some of the other problems that the stricken plant, regulators and operator Tokyo Electric Power Co. were grappling with.
Expert panel to address radiologic impact on animals near Japan nuclear plant
Japan nuclear disaster animal relief planning
Drs. Kelly Preston and Gordon Cleveland, both with the U.S. Department of Agriculture, confer with two Japanese professors with the help of a translator.
The International Fund for Animal Welfare in April announced a team of radiation and animal rescue experts had been assembled to develop a plan for aiding animals inside the evacuation zone around the damaged Fukushima Daiichi Nuclear Power Plant in Japan.
Limited data are available about decontaminating and treating animals affected by radiation, and standards don't exist for determining whether an animal has been exposed to an unsafe level of radiation. Moreover, little is known about the survivability of wildlife and pets, or the viability of farm animals, exposed to radiation.
The goal of the IFAW-led summit is to develop... www.avma.org...
Originally posted by Tworide
A review of the reactor logs shows that the steam driven isolation condensers were shut down by the operators after the quake, but before the tsunami.
Documents released by Tepco Monday showed the isolation condenser— an emergency cooling system installed on Reactor No. 1 before the quake as a final resort in case of a total loss of power—worked only sporadically, if at all.
Unit 1 did not have the steam-driven vessel makeup system that was installed and used on Units 2 and 3. Unit 1 had what is called an isolation condenser to perform vessel water inventory control and vessel pressure control (see Figure 2).
The isolation condenser is a large tank of water. If the normal makeup flow of water to the reactor vessel is lost, battery-powered valves open to allow steam produced by decay heat in the reactor core to flow through thousands of tubes in the isolation condenser. That steam is condensed back into water and flows by gravity to the reactor vessel. This process controls the amount of water in the pressure vessel, since it limits the steam (and thus water) lost through relief valves to the torus (which is part of the primary containment vessel).
This process also controls the reactor vessel pressure, since the water in the isolation condenser absorbs decay heat that would otherwise cause the pressure inside the reactor vessel to rise.
But the water inside the isolation condenser is of finite volume. In less than 90 minutes after a reactor shut down from 100 percent power, the decay heat from the reactor core will have warmed that water to the point of boiling and begun to boil it away. Boiling water reactors with isolation condensers are supposed to use electric powered pumps to refill the isolation condenser tanks well before its water boils away. Workers at Fukushima had no pumps available to top off the tank after the earthquake took away the normal power supply and the tsunami took away the backup power supply.
It’s worth noting that modeling of the crisis indicates that meltdowns should have occurred at all three reactors (1. 2, and 3), given the length of time they were all without cooling. The modeling also suggests that without cooling the molten fuel would have melted through the bottom of the reactor vessel about 7 hours after the fuel relocated to the bottom of the vessel. TEPCO says that cooling water was injected in to prevent this. According to Figure 1, the injection of cooling water started about 10 hours after the water level dropped below the bottom of the fuel in the reactor.
Originally posted by Hellhound604
reply to post by Tworide
SO, are you telling me that a car's ABS system (that doesn't allow human override (unless you are a hacker) ) is safer than a nuclear reactor???? OMG, then the nuclear industry got what they deserved!!!!!!! (pity about the innocent bystanders)
THE CRISIS HITS HOME IN HOKKAIDO
For a look at how badly the Japanese crisis can affect the lives of ordinary citizens, just head for Sapporo, the capital of Hokkaido, Japan's northernmost island. The failure of Hokkaido Takushoku Bank Ltd., the dominant local bank, has dealt a devastating blow to the island's already fragile economy. And its citizens now worry that public works projects in their prefecture may soon dry up, as the central government in Tokyo runs out of funds. www.businessweek.com...
JAPAN'S REAL CRISIS
Until its hidden debt mess is cleared up, no recovery is possible
If only Japan would listen. That sentiment, in one form or another, has been a favorite among foreign governments, executives, and commentators for years. In the 1970s, as the Japanese created the world's most dynamic automobile industry, Americans urged them to curb their exports. When Japan rode a wave of prosperity in the 1980s, Western governments demanded that the country open up its restricted markets. And today, as Japan staggers into recession, finance ministries around the world are begging the government of Prime Minister Ryutaro Hashimoto to spend, spend, spend. Cut taxes, Mr. Hashimoto. Prime the pump by tapping Japan's $10 trillion in savings. Just act, and you can kick off a recovery in Asia that will prevent a global slowdown and end the region's crisis. www.businessweek.com...
CLYDE PRESTOWITZ: VIEWS FROM AN OLD JAPAN TRADE HAWK
Q: How sick is the Japanese economy?
A: I think Japan is in serious trouble, and it will take them awhile to get out of it. I don't think they can really get out of the swamp without struggling with deregulation and a restructuring of the economy. I don't mean just Big Bang stuff, but getting government out of all businesses and really breaking up the cartels and quasi-cartels. That will require significant political changes and cause significant pain to vested interests. www.businessweek.com...
Originally posted by Hellhound604
I fully agree with you. I last learnt about nuclear reactors more than 30years ago in an introductory engineering course, and I always assumed, that due to the weaknesses of the simplified reactors we learnt about (BWR's), that nobody would ever, ever use them..... So, it came as quite a shock to me to learn that Fukushima used that actual design ..... and now it is even worse, when all the fail-safe systems failed!!!!!! The designers of these systems should be put in front of a firing squad..... or even better, they should go out and clean their mess themselves, instead of sending poor lackeys to do their dirty work.edit on 18/5/2011 by Hellhound604 because: grrr.... now I have a finger-mousepad coordination problem.....
Nuclear Expert Warns Congress U.S. Power Plants Not Safe
Submitted by webEditor on Mon, 05/16/2011 - 13:26
Congressional lawmakers were warned today that U.S. nuclear power plants are by no means safe and that government agency and nuclear industry representatives have not been telling the whole story.
David Lochbaum, a nuclear engineer who serves as director of the Nuclear Safety Project with the Union of Concerned Scientists, has the credentials to know whereof he speaks. From March 2009 until March 2010, Lochbaum worked for the Nuclear Regulatory Commission as a Boiling Water Reactor technology instructor at their Technical Training Center.
His duties included teaching the severe accident management guidelines to NRC employees for their initial qualifications and requalifications.
Lochbaum was asked to testify before a joint session of the Energy and Environment and Investigations and Oversight Subcommittees of the House of Representatives Committee on Science, Space, and Technology.
Read more www.tmia.com...
NRC: Meeting with petitioner requesting GE BWRs Mark I Reactors license suspension
Submitted by webEditor on Mon, 05/16/2011 - 13:23
FORTHCOMING MEETING WITH PETITIONER REQUESTING ACTION UNDER 10 CFR 2.206 REGARDING IMMEDIATE SUSPENSION OF THE OPERATING LICENSES OF GENERAL ELECTRIC (GE) BOILING WATER REACTORS (BWRs) MARK I UNITS BOILING WATER REACTORS ML11126A096