Category Archive 'Nuclear Power'

22 Mar 2011

Reactor Containment Chambers and Samurai Swords

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Ogata Gekkō, Heian swordsmith Munechika, aided by the kami Inari, forging the blade Ko-Gitsune Maru (“Little Fox”), 1873

George Monbiot (the original moonbat), the very last person in the world whom you would ever expect to become pro-nuke, says that events in Fukushima have caused him to stop worrying and love nuclear power.

You will not be surprised to hear that the events in Japan have changed my view of nuclear power. You will be surprised to hear how they have changed it. As a result of the disaster at Fukushima, I am no longer nuclear-neutral. I now support the technology.

A crappy old plant with inadequate safety features was hit by a monster earthquake and a vast tsunami. The electricity supply failed, knocking out the cooling system. The reactors began to explode and melt down. The disaster exposed a familiar legacy of poor design and corner-cutting. Yet, as far as we know, no one has yet received a lethal dose of radiation.


The effectiveness of the containment at Fukushima is based on single-piece steel containment chambers, built by Japan Steel Works, (株式会社日本製鋼所, Kabushikigaisya Nihon Seikōsho), a steel manufacturer founded in Muroran, Hokkaidō, Japan in 1907, which traces its technological heritage directly back to the native Japanese steel-making tradition which produced the Japanese samurai sword.

Justin Hyde:

As fears rise in Japan about nuclear disaster at the Fukushima plant, the first and best line of defense are the reactor’s six inch thick steel-walled chambers, made by a company that still forges samurai swords by hand.

Japan Steel Works is the world’s only volume builder of nuclear reactor vessels, the steel container that holds radioactive fuel, and in case of a meltdown, prevents that fuel from leaking and triggering a catastrophe. Founded in 1907 and rebuilt following World War II, it supplied nearly all of the vessels used in Japan’s 54 nuclear power plants, including the containers at the Fukushima Daiichi plants designed by General Electric and Toshiba.

While those vessels were made from steel plates bolted and welded together, modern designs require Japan Steel Works to forge containers from a single ingot that can weigh up to 600 tons. It’s a slow process that takes months at a time, using the company’s 14,000-ton press to shape a special steel alloy that’s been purified to maximize its strength. These methods also minimize seams that can give way in case of a meltdown, where nuclear fuel can reach 2,000 degrees Celsius.

Although Japan Steel Works is a major corporation with 5,000 employees, it also maintains a samurai sword blacksmith, in a small shack on a hill above the factory in Muroran, where a single craftsman still hammers steel into broadswords, as the company has done since 1917.


Japan Steel Works founded its smithy in 1918 by recruiting Taneaki Horii, whose teacher Taneyoshi Horii (c. 1820-1903), had studied under Gassan Sadayoshi (1800-1870), founder of the Osaka Gassan school, and under Taikei Naotane (c. 1777-1857).

Naotane was himself the pupil of Suishinshi Masahide (1750-1825) of Edo, the founder of the Shinshinto (New Revival) period of sword-making. Masahide criticized the showiness and practical defects of the Shinto sword, and advocated the building instead of the fukko-to, “the Restoration sword,” by returning to the sword-making techniques and styles of the Heian and Kamakura periods.


Current master Horii Tanetada making a sword and a tour of the Zuisen Sword Smithy


Horii swords displayed at exhibition hall

16 Mar 2011

Josef Oehmer May Have Been a Little Too Optimistic

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There were additional hydrogen gas explosions in Units 1 and 3 and Unit 2’s containment may have been breached. (MIT Nuclear Science and Engineering – NSE)

Unit 2’s explosion damaged the suppression chamber and leaking oil caught fire and burned for two hours yesterday in Unit 4’s spent fuel pool. (NSE)

Reactor crews are preparing to re-enter after having been withdrawn yesterday due to dangerously rising levels of radiation.

A small cadre of 50 (to 70) workers out of a staff of more than 800 made world-wide news by remaining behind to carry out “last defense” measures to control the reactors. GuardianNew York Times

14 Mar 2011

MIT Scientist: Fukushima Came Close to Meltdown, But Did Shutdown Safely

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Nuclear power plant explosion at Fukushima

CORRECTION: Yesterday’s original photograph (found at Business Insider) was actually a natural gas facility at Chiba, not the Fukushima reactor. Thanks to K for catching this.

Ignore the screaming headlines on Drudge produced by the mainstream media. Josef Oehmen, an MIT research scientist with a doctorate in Mechanical Engineering, explains that the operators of the Japanese nuclear power plant at Fukushima were very unlucky and suffered a hydrogen gas explosion. It came close to the limits of its safety design, but did actually remain within them.

I am writing this text (Mar 12) to give you some peace of mind regarding some of the troubles in Japan, that is the safety of Japan’s nuclear reactors. Up front, the situation is serious, but under control. And this text is long! But you will know more about nuclear power plants after reading it than all journalists on this planet put together.

There was and will *not* be any significant release of radioactivity.

By “significant” I mean a level of radiation of more than what you would receive on – say – a long distance flight, or drinking a glass of beer that comes from certain areas with high levels of natural background radiation.

I have been reading every news release on the incident since the earthquake. There has not been one single (!) report that was accurate and free of errors (and part of that problem is also a weakness in the Japanese crisis communication). By “not free of errors” I do not refer to tendentious anti-nuclear journalism – that is quite normal these days. By “not free of errors” I mean blatant errors regarding physics and natural law, as well as gross misinterpretation of facts, due to an obvious lack of fundamental and basic understanding of the way nuclear reactors are build and operated. I have read a 3 page report on CNN where every single paragraph contained an error. …

At some stage during this venting, [an] explosion occurred. The explosion took place outside of the third containment ([the] “last line of defense”), and the reactor building. Remember that the reactor building has no function in keeping the radioactivity contained. It is not entirely clear yet what has happened, but this is the likely scenario: The operators decided to vent the steam from the pressure vessel not directly into the environment, but into the space between the third containment and the reactor building (to give the radioactivity in the steam more time to subside). The problem is that at the high temperatures that the core had reached at this stage, water molecules can “disassociate” into oxygen and hydrogen – an explosive mixture. And it did explode, outside the third containment, damaging the reactor building around. It was that sort of explosion, but inside the pressure vessel (because it was badly designed and not managed properly by the operators) that lead to the explosion of Chernobyl. This was never a risk at Fukushima. The problem of hydrogen-oxygen formation is one of the biggies when you design a power plant (if you are not Soviet, that is), so the reactor is build and operated in a way it cannot happen inside the containment. It happened outside, which was not intended but a possible scenario and OK, because it did not pose a risk for the containment.

So the pressure was under control, as steam was vented. Now, if you keep boiling your pot, the problem is that the water level will keep falling and falling. The core is covered by several meters of water in order to allow for some time to pass (hours, days) before it gets exposed. Once the rods start to be exposed at the top, the exposed parts will reach the critical temperature of 2200 °C after about 45 minutes. This is when the first containment, the Zircaloy tube, would fail.

And this started to happen. The cooling could not be restored before there was some (very limited, but still) damage to the casing of some of the fuel. The nuclear material itself was still intact, but the surrounding Zircaloy shell had started melting. What happened now is that some of the byproducts of the uranium decay – radioactive Cesium and Iodine – started to mix with the steam. The big problem, uranium, was still under control, because the uranium oxide rods were good until 3000 °C. It is confirmed that a very small amount of Cesium and Iodine was measured in the steam that was released into the atmosphere.

It seems this was the “go signal” for a major plan B. The small amounts of Cesium that were measured told the operators that the first containment on one of the rods somewhere was about to give. The Plan A had been to restore one of the regular cooling systems to the core. Why that failed is unclear. One plausible explanation is that the tsunami also took away / polluted all the clean water needed for the regular cooling systems.

The water used in the cooling system is very clean, demineralized (like distilled) water. The reason to use pure water is the above mentioned activation by the neutrons from the Uranium: Pure water does not get activated much, so stays practically radioactive-free. Dirt or salt in the water will absorb the neutrons quicker, becoming more radioactive. This has no effect whatsoever on the core – it does not care what it is cooled by. But it makes life more difficult for the operators and mechanics when they have to deal with activated (i.e. slightly radioactive) water.

But Plan A had failed – cooling systems down or additional clean water unavailable – so Plan B came into effect. This is what it looks like happened:

In order to prevent a core meltdown, the operators started to use sea water to cool the core. I am not quite sure if they flooded our pressure cooker with it (the second containment), or if they flooded the third containment, immersing the pressure cooker. But that is not relevant for us.

The point is that the nuclear fuel has now been cooled down. Because the chain reaction has been stopped a long time ago, there is only very little residual heat being produced now. The large amount of cooling water that has been used is sufficient to take up that heat. Because it is a lot of water, the core does not produce sufficient heat any more to produce any significant pressure. Also, boric acid has been added to the seawater. Boric acid is “liquid control rod”. Whatever decay is still going on, the Boron will capture the neutrons and further speed up the cooling down of the core.

The plant came close to a core meltdown. …

The plant is safe now and will stay safe.

Japan is looking at an INES Level 4 Accident: Nuclear accident with local consequences. That is bad for the company that owns the plant, but not for anyone else.

Some radiation was released when the pressure vessel was vented. All radioactive isotopes from the activated steam have gone (decayed). A very small amount of Cesium was released, as well as Iodine. If you were sitting on top of the plants’ chimney when they were venting, you should probably give up smoking to return to your former life expectancy. The Cesium and Iodine isotopes were carried out to the sea and will never be seen again.

There was some limited damage to the first containment. That means that some amounts of radioactive Cesium and Iodine will also be released into the cooling water, but no Uranium or other nasty stuff (the Uranium oxide does not “dissolve” in the water). There are facilities for treating the cooling water inside the third containment. The radioactive Cesium and Iodine will be removed there and eventually stored as radioactive waste in terminal storage.

The seawater used as cooling water will be activated to some degree. Because the control rods are fully inserted, the Uranium chain reaction is not happening. That means the “main” nuclear reaction is not happening, thus not contributing to the activation. The intermediate radioactive materials (Cesium and Iodine) are also almost gone at this stage, because the Uranium decay was stopped a long time ago. This further reduces the activation. The bottom line is that there will be some low level of activation of the seawater, which will also be removed by the treatment facilities.

The seawater will then be replaced over time with the “normal” cooling water.

The reactor core will then be dismantled and transported to a processing facility, just like during a regular fuel change.

Fuel rods and the entire plant will be checked for potential damage. This will take about 4-5 years.

The safety systems on all Japanese plants will be upgraded to withstand a 9.0 earthquake and tsunami (or worse).

Read the whole thing.

The Explosion:

17 Sep 2007

More People Died in the Back Seat of Ted Kennedy’s Car

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Unhappy about CO2 emissions from fossil-fuel-powered electrical generating plants? Blame Jane Fonda, Stephen J. Dubner and Steven D. Levitt advise.

If you were asked to name the biggest global-warming villains of the past 30 years, here’s one name that probably wouldn’t spring to mind: Jane Fonda. But should it?

In the movie “The China Syndrome,” Fonda played a California TV reporter filming an upbeat series about the state’s energy future. While visiting a nuclear power plant, she sees the engineers suddenly panic over what is later called a “swift containment of a potentially costly event.” When the plant’s corporate owner tries to cover up the accident, Fonda’s character persuades one engineer to blow the whistle on the possibility of a meltdown that could “render an area the size of Pennsylvania permanently uninhabitable.”

“The China Syndrome” opened on March 16, 1979. With the no-nukes protest movement in full swing, the movie was attacked by the nuclear industry as an irresponsible act of leftist fear-mongering. Twelve days later, an accident occurred at the Three Mile Island nuclear plant in south-central Pennsylvania. …

The T.M.I. accident was, according to a 1979 President’s Commission report, “initiated by mechanical malfunctions in the plant and made much worse by a combination of human errors.” Although some radiation was released, there was no meltdown through to the other side of the Earth — no “China syndrome” — nor, in fact, did the T.M.I. accident produce any deaths, injuries or significant damage except to the plant itself.

What it did produce, stoked by “The China Syndrome,” was a widespread panic. The nuclear industry, already foundering as a result of economic, regulatory and public pressures, halted plans for further expansion. And so, instead of becoming a nation with clean and cheap nuclear energy, as once seemed inevitable, the United States kept building power plants that burned coal and other fossil fuels. Today such plants account for 40 percent of the country’s energy-related carbon-dioxide emissions. Anyone hunting for a global-warming villain can’t help blaming those power plants — and can’t help wondering too about the unintended consequences of Jane Fonda.

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