Japan's turn

[Agentm]

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. Here is the worst-case scenario that was avoided: If the seawater could not have been used for treatment, the operators would have continued to vent the water steam to avoid pressure buildup. The third containment would then have been completely sealed to allow the core meltdown to happen without releasing radioactive material. After the meltdown, there would have been a waiting period for the intermediate radioactive materials to decay inside the reactor, and all radioactive particles to settle on a surface inside the containment. The cooling system would have been restored eventually, and the molten core cooled to a manageable temperature. The containment would have been cleaned up on the inside. Then a messy job of removing the molten core from the containment would have begun, packing the (now solid again) fuel bit by bit into transportation containers to be shipped to processing plants. Depending on the damage, the block of the plant would then either be repaired or dismantled.


Now, where does that leave us?


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) I believe the most significant problem will be a prolonged power shortage. About half of Japan 's nuclear reactors will probably have to be inspected, reducing the nation's power generating capacity by 15%. This will probably be covered by running gas power plants that are usually only used for peak loads to cover some of the base load as well. That will increase your electricity bill, as well as lead to potential power shortages during peak demand, in Japan .



If you want to stay informed, please forget the usual media outlets and consult the following websites:
http://www.world-nuclear-news.org/RS_Battle_to_stabilise_earthquake_reac...
http://www.world-nuclear-news.org/RS_Venting_at_Fukushima_Daiichi_3_1303...
http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/
http://ansnuclearcafe.org/2011/03/11/media-updates-on-nuclear-power-stat...

 

[basilio]

Thank you for the information Agentum. Very interesting and I hope a realistic portrayal of what is happening.

I have to say however this situation will only subside when there is clear evidence that the reactor cores are cooling and that there is no significant escape of radioactive material. Let's pray..

 

[spooly74]

http://www.jaif.or.jp/english/news/2011/110315fukushima_event-status-5.pdf

 

[skc]

Live webcam feed into the Fukushima nuclear power plant control room.



Sorry just my attempt at some dark humour...everything is just so sad.

 

[Julia]

Sorry just my attempt at some dark humour...everything is just so sad.

I know what you mean. I look at the horror of it all and just have to walk away, feeling like a total coward.

 

[Mofra]

Thank you for the information Agentum. Very interesting and I hope a realistic portrayal of what is happening.

Ditto - obviously hysteria sells newspapers, but it's good to have a realistic handle on the situation.

 

[basilio]

Controlling the meltdown in the nuclear reactor is not going according to Hoyle. Last statement in the media was that the power company is withdrawing the last 50 workers because the radiation levels are too high. They are now appealing to the US military for help.

Back in the USSR and Chernobyl I understand a number of employees continued to work to somehow secure the plant even as they were getting deadly amounts of radiation. Tragic but true - and totally heroic..

Work on stricken Japan reactor suspended
March 16, 2011 - 4:14PM


Japan quake clouds US nuclear future

The explosions and fire at Japanese nuclear plant raises new questions about the safety of nuclear power.

Japan has suspended operations to keep its stricken nuclear plant from melting down after surging radiation made it too dangerous for workers to stay.

Chief Cabinet Secretary Yukio Edano said the workers dousing the reactors in a frantic effort to cool them needed to withdraw.

‘‘The workers cannot carry out even minimal work at the plant now,’’ Edano said. ‘‘Because of the radiation risk we are on standby,’’ he said.
..Edano said the government expects to ask the US military for help. He did not elaborate. He said the government is still considering whether and how to take up the various offers of help from other countries.

The surge in radiation was apparently the result of a Tuesday explosion in the complex’s Unit 4 reactor, according to officials with Japan’s nuclear safety agency.

That blast is thought to have damaged the reactor’s suppression chamber, a water-filled pipe outside the nuclear core that is part of the emergency cooling system.

Officials had originally planned use helicopters and fire trucks to spray water in a desperate effort to prevent further radiation leaks and to cool down the reactors.

‘‘It’s not so simple that everything will be resolved by pouring in water. We are trying to avoid creating other problems,’’ Edano said."

http://www.theage.com.au/world/work-on-stricken-japan-reactor-suspended-20110316-1bx0p.html

 

[IFocus]

Thank you for the information Agentum, what I don't get is the genset plugs did not fit.

You would simply hard wire them temporary not a big deal must be more to the story.

 

[IFocus]

Controlling the meltdown in the nuclear reactor is not going according to Hoyle. Last statement in the media was that the power company is withdrawing the last 50 workers because the radiation levels are too high. They are now appealing to the US military for help.

Back in the USSR and Chernobyl I understand a number of employees continued to work to somehow secure the plant even as they were getting deadly amounts of radiation. Tragic but true - and totally heroic..



http://www.theage.com.au/world/work-on-stricken-japan-reactor-suspended-20110316-1bx0p.html

Current group of worker would have had potential deadly doses already.

 

[skc]

Thank you for the information Agentum, what I don't get is the genset plugs did not fit.

You would simply hard wire them temporary not a big deal must be more to the story.

Exactly my thoughts... sure may be it is acceptable that my camera charger's plug didn't fit the socket at the hotel on my last overseas holiday.

It's a nuclear power plant ffs.

 

[ThingyMajiggy]

But wait, there's more.

http://www.zerohedge.com/article/he...nits-4-5-and-6-total-4-units-have-core-damage

http://www.zerohedge.com/article/usdjpy-plunging-drops-16-year-low

 

[Agentm]

the levels are not over the top imho, they basically require people to stay indoors

of course the alarm in peoples minds and the concern is that high levels of radiation could potentially occur if things go wrong from here



Fukushima Nuclear Accident – 16 March update

Posted on 16 March 2011 by Barry Brook

This is an update of the situation as of 10 am JST Wednesday 16 March. (For background on events of 15 March and earlier, start with this post and its included links.) Note that this is a blog, not a news website, and thus the following analysis, like all others on BraveNewClimate, is a mixture of news and opinion ”” but facts remain paramount.
First, the situation is clearly (but slowly) stabilising. As each day passes, the amount of thermal heat (caused by radioactive decay of the fission products) that remains in the reactor fuel assemblies decreases exponentially. When the reactors SCRAMed on 11 March after the earthquake, and went sub-critical, their power levels dropped by about 95 % of peak output (the nuclear fission process was no longer self-sustaining). Over the past 5 days, the energy in the fuel rods dropped by another ~97 %, such that the heat dissipation situation is getting more and more manageable. But we’re not out of the woods yet, and the reactor cores will need significant cooling for at least another 5 days before stability can be ensured.
Yesterday there appears to have been a fracture in the wetwell torus (see diagram: that circular structure below and to the side of the reactor vessel) in Unit 2, caused by a hydrogen explosion, which led to a rapid venting of highly radioactive fission product gases (mostly noble [chemically unreactive] gases, the majority of which had a half-life of seconds to minutes). It also caused a drop in pressure in the supression pool, which made the cooling process more challenging. However, despite some earlier concerns, it is now clear that containment was not breached. Even under this situation of extreme physical duress, the multiple containment barriers have held firm. This is an issue to be revisited, when the dust finally settles.
Units 1 and 3, the other two operating reactors at Fukushima Daiichi when the earthquake struck, continue to be cooled by sea water. Containment is secure in both units. However, like Unit 2, there is a high probability that the fuel assemblies have likely suffered damage due to temporary exposure (out of water), as the engineers struggled over the last few days to maintain core coolant levels. Whether there has been any melting of the clad or rods remains unclear, and probably will continue to be shrouded in a cloud of uncertainty for some time yet.

The other ongoing serious issue is with managing the heat dissipation in the spent fuel ponds. These contain old fuel rods from previous reactor operation that are cooling down, on site, immersed in water, which also provides radiation shielding. After a few years of pond cooling, these are transferred to dry storage. The heat in these rods is much less than those of the in-core assemblies, but it is still significant enough as to cause concern for maintaining adequate coverage of the stored fuel and to avoid boiling the unpressurised water. There have been two fires in Unit 4, the first tentatively linked to a failed oil pump, and the second, being of (currently) unknown cause, but the likelihood is that it was linked to hydrogen gas bubbling.
There appears to have been some exposure of this spent fuel, and radiation levels around this area remain high ”” making access in order to maintain water levels particularly troublesome. Note that apart from short-lived fission product gases, these radiation sources are otherwise contained within the rods and not particularised in a way that facilitates dispersion. Again, the problems encountered here can be linked to the critical lack of on-site power, with the mains grid still being out of action. As a further precaution, TEPCO is considering spraying the pool with boric acid to minimise the probability of ‘prompt criticality’ events. This is the news item we should be watching most closely today.
An excellent 2-page fact sheet on the spent fuel pool issues has been produced by the NEI, which can be read here: Used Nuclear Fuel Storage at the Fukushima Daiichi Nuclear Power Plant (this includes an explanation of what might happen under various scenarios).
This figure illustrates the current reported state of the Daiichi and Daini reactors, last updated 1230 on 16 March (click to enlarge):

The status report from the The Federation of Electric Power Companies of Japan (FEPC) is given below:​

• Radiation Levels
o At 10:22AM (JST) on March 15, a radiation level of 400 milli sievert per hour was recorded outside secondary containment building of the Unit 3 reactor at Fukushima Daiichi Nuclear Power Station.
o At 3:30PM on March 15, a radiation level of 596 micro sievert per hour was recorded at the main gate of Fukushima Daiichi Nuclear Power Station.
o At 4:30PM on March 15, a radiation level of 489 micro sievert per hour was recorded on the site of the Fukushima Daiichi Nuclear Power Station.
o For comparison, a human receives 2400 micro sievert per year from natural radiation in the form of sunlight, radon, and other sources. One chest CT scan generates 6900 micro sievert per scan.
• Fukushima Daiichi Unit 1 reactor
o As of 10:00PM on March 14, the pressure inside the reactor core was measured at 0.05 MPa. The water level inside the reactor was measured at 1.7 meters below the top of the fuel rods.
• Fukushima Daiichi Unit 2 reactor
o At 6:14AM on March 15, an explosion was heard in the secondary containment building. TEPCO assumes that the suppression chamber, which holds water and stream released from the reactor core, was damaged.
o At 1:00PM on March 15, the pressure inside the reactor core was measured at 0.608 MPa. The water level inside the reactor was measured at 1.7 meters below the top of the fuel rods.
• Fukushima Daiichi Unit 3 reactor
o At 6:14AM on March 15, smoke was discovered emanating from the damaged secondary containment building.
• Fukushima Daiichi Unit 4 reactor
o At 9:38AM on March 15, a fire was discovered on the third floor of the secondary containment building.
o At 12:29PM on March 15, TEPCO confirmed extinguishing of the fire.
• Fukushima Daini Units 1 to 4 reactors: all now in cold shutdown, TEPCO continues to cool each reactor core.
This indicates a peak radiation level of 400 mSv/hr, which has come down to about 0.5 mSv/hr by the afternoon. This ‘spot’ radiation level was measured at a location between Unit 3 and 4. It was attributted to a hydrogen explosion in the spent fuel pool of Unit 4 ”” but this is still under debate. The radiation level at the site boundary is expected to have been much lower and, to date, there is no risk to the general public.

 

[Agentm]

Two other useful sources of information are from the WNN: Radiation decreasing, fuel ponds warming and Second fire reported at unit 4. ANS Nuclear Cafe continues to be a great collator of key official channels and top news stories.
Finally, this is a useful perspective from an MIT staffer that is well worth reading:
What happened at the Fukushima reactor? Events in Japan confirm the robustness of modern nuclear technology ”” not a failure
Kirk Sorenson, from Energy from Thorium blog, also has this very interesting piece: Thoughts on Fukushima-Daiichi. A concluding excerpt:

What is known is that this is a situation very different than Chernobyl or Three Mile Island. There was no operator error involved at Fukushima-Daiichi, and each reactor was successfully shut down within moments of detecting the quake. The situation has evolved slowly but in a manner that was not anticipated by designers who had not assumed that electrical power to run emergency pumps would be unavailable for days after the shutdown. They built an impressive array of redundant pumps and power generating equipment to preclude against this problem. Unfortunately, the tsunami destroyed it.
There are some characteristics of a nuclear fission reactor that will be common to every nuclear fission reactor. They will always have to contend with decay heat. They will always have to produce heat at high temperatures to generate electricity. But they do not have to use coolant fluids like water that must operate at high pressures in order to achieve high temperatures. Other fluids like fluoride salts can operate at high temperatures yet at the same pressures as the outside. Fluoride salts are impervious to radiation damage, unlike water, and don’t evolve hydrogen gas which can lead to an explosion. Solid nuclear fuel like that used at Fukushima-Daiichi can melt and release radioactive materials if not cooled consistently during shutdown. Fluoride salts can carry fuel in chemically-stable forms that can be passively cooled without pumps driven by emergency power generation. There are solutions to the extreme situation that was encountered at Fukushima-Daiichi, and it may be in our best interest to pursue them.
​

More updates as further information comes to hand. Otherwise, for me, it’s back to the mad TV and radio media circus.
UPDATE: From World Nuclear News: Problems for units 3 and 4Chief Cabinet Secretary Yukio Edano had outlined problems that had occured on the morning of 16 March with Fukushima Daiichi 3 and 4.
At 8:34am local time white smoke was seen billowing out of Fukushima Daiichi 3. Efforts to determine the cause of this development were interrupted as all workers had evacuated to a safe area due to rising radiation readings. Readings from a sensor near the front gate had fluctuated for some time, although Edano said that on the whole there was no health hazard. Earlier in the morning readings had ranged between 600-800 microsieverts per hour, but at 10am readings rose to 1000 microsieverts per hour. Readings began to fall again from around 10:54.
Edano said that one possibility being considered was that the unit 3 reactor had suffered a similar failure to that suffered by unit 2 yesterday, although there had been no reported blast or loud sound, which had been the case for unit 2. The immediate focus, said Edano was on monitoring of levels and checking pumping operations.
Edano also outlined plans for units 4-6. Preparations were being made to inject water into unit 4, however the high levels of radiation from unit 3 were imparing those preparations. When possible, the water injection would be done gradually as there were safety concerns over pouring a large amount of water at once. The water will be pumped into the reactor building from the ground, plans to drop water from a helicopter having been abandoned. Although he said that “all things were possible” Edano did not believe that recriticality at unit 4 was a realistic risk
Second fire at unit 4
Earlier, the Nuclear and Industrial Safety Agency said that a blaze was spotted in the reactor building of Fukushima Daiichi 4 at 5.45am local time this morning.
Attempts to extinguish it were reportedly delayed due to high levels of radiation in the area. A spokesperson for TEPCO said that by around 6:15am there were no flames to be seen.
The incident at unit 4 is believed to be in the region of a used fuel pond in the upper portion of the reactor building.
Origins
Tokyo Electric Power Company issued a notice of an explosion at unit 4 at 6am on 15 March. This was followed by the company’s confirmation of damage around the fifth floor rooftop area of the reactor building.
On that day, a fire was discovered but investigations concluded it had died down by around 11am.
At present it is not clear whether today’s fire was a completely new blaze, or if the fire reported yesterday had flared up again.

 

[Knobby22]

Check your sources AgentM

From the Murdoch Press this mornings paper - Terry McCrann - Nuclear hysteria will fade. China syndrome can't happen , ....and Insanity. (referring to hysteria)

From the ABC - The US Nuclear Regulatory Commission (NRC) has warned there is no water left in the spent fuel pool of reactor No. 4 at the plant, resulting in "extremely high" radiation levels.

NRC chief Gregory Jaczko says if the US were facing a similar situation it would order a much larger evacuation zone.

The US has called on Americans within 80 kilometres of the nuclear plant area to leave.

Those who believed other sources and bought nuclear stocks yesterday will be reconsidering where they get their information. I would be getting out today, if I were them, as soon as possible. This is a horrible disaster and I feel for the Japanese. Whole areas of the country will be left uninhabitable. As for the nuclear workers - I pity them and their families, they should be remembered as heroes. It is not their fault that design of the plant was inadequate.

 

[spooly74]

Check your sources AgentM

From the Murdoch Press this mornings paper - Terry McCrann - Nuclear hysteria will fade. China syndrome can't happen , ....and Insanity. (referring to hysteria)

From the ABC - The US Nuclear Regulatory Commission (NRC) has warned there is no water left in the spent fuel pool of reactor No. 4 at the plant, resulting in "extremely high" radiation levels.

Any figures with "extremely high" radiation levels?
Without them, it's a pointless statement. Dose vs distance if possible.

Also, the Japanese have denied the statement that the fuel ponds are empty.
Wait and see.

It is not their fault that design of the plant was inadequate.

Backseat engineering with hindsight after one of the biggest quakes ever recorded and a 7m tsunami, what a luxury.

 

[Knobby22]

Backseat engineering with hindsight after one of the biggest quakes ever recorded and a 7m tsunami, what a luxury.

Such ignorance.

The GE reactors are widely recognised as being of poor design.

Look at this site.

http://globaleconomicanalysis.blogspot.com/

 

[Smurf1976]

What if there had been a 9.5 earthquake straight under the plant? What if terrorists attacked the plant after the earthquake and tsunami? What if...

Will man never learn that we can not possibly foresee every scenario and that there is always some risk? Indeed that there is always some risk is explicitly acknowledged in the design of such things, it's just that we chose to build them anyway. No engineer designing any complex system will guarantee you 100% safety under all circumstances. It just can't be done.

At the end of the day, it's a power station. Electricity generation shouldn't be this exciting. It shouldn't be endangering so many people. With the outright fortune being spent at this plant, plus all that spent on the security etc of nuclear plants worldwide over the years, I'm sure we could have made some other power source work with that sort of resources available.

With the costs of this nuclear disaster, a combination of wind, solar, geothermal and hydro plus some coal and gas would probably have been cheaper anyway. And it's certainly not going to melt down and scare the **** out of everyone in the entire region.

 

[basilio]

Everyone is certainly getting up to speed with the ins and outs of nuclear reactors...

The good news. It seems as if everyone agrees that the difference in design and material use between the Chernobyl reactor and the Japanese ones means there can't be an explosion of the intensity and radioactive carry of Chernobyl.

The bad news Apparently the use of plutonium enriched fuel rods in the No 3 reactor opens the possibility of very dangerous local contamination if there is any large scale radiation discharge. The emitted plutonium particles are highly likely to cause cancers.

So why did they have these plutonium enriched (MOX) fuel rods? It seems like this was a good way of getting rid of a dangerous nuclear byproduct. This artcile is well worth a read.


[

B]MOX fuel rods used in Japanese Nuclear Reactor present multiple dangers[/B] Print
Tuesday, 15 March 2011
Written by Joseph Trento


The mixed oxide fuel rods used in the compromised number three reactor at the Fukushima Daiichi complex contain enough plutonium to threaten public health with the possibility of inhalation of airborne plutonium particles. The compromised fuel rods supplied to the Tokyo Electric Company by the French firm AREVA.

Plutonium is at its most dangerous when it is inhaled and gets into the lungs. The effect on the human body is to vastly increase the chance of developing fatal cancers.

Masashi Goto, a reactor researcher and designer for Toshiba, told the Foreign Correspondents Club in Toyko the mixed oxide (MOX) fuel used in unit 3 of the Fukushima Daiichi nuclear facility uses plutonium, which is “much more toxic than the fuel used in the other reactors.”

Goto said that the MOX also has a lower melting point than the other reactor fuels. The Fukushima facility began using MOX fuel in September 2010, becoming the third plant in Japan to do so, according to MOX supplier AREVA.

Part of the process of making MOX fuel is to grind plutonium into a fine power before it is robotically inserted into fuel rods. Experts agree these tiny plutonium particles once airborne are extremely dangerous to human health.

One of the unique characteristics of mixed oxide fuel is that relatively little of the plutonium in the fuel rods is used up in the fuel cycle in a reactor. “When the plutonium in the fuel rods goes into a reactor for commercial power, a very little of it is going to be consumed. I don’t know what percentage, maybe half percentage or something like that, but it’s going to generate an extraordinary amount of contamination throughout the fuel rods…,” says William Lawler, an expert on radioactive waste.

http://dcbureau.org/201103151304/Na...onium-a-threat-from-reactor-number-three.html

 

[spooly74]

Such ignorance.

The GE reactors are widely recognised as being of poor design.

Look at this site.

http://globaleconomicanalysis.blogspot.com/

Is this your reference from the link?

A General Electric Co engineer said he resigned 35 years ago over concern about the safety of a nuclear reactor design used in the now crippled Fukushima Daiichi plant in Japan.

Dale Bridenbaugh said the "Mark 1" design had "not yet been designed to withstand the loads" that could be experienced in a large-scale accident.

"At the time, I didn't think the utilities were taking things seriously enough," Bridenbaugh, now retired, said in a phone interview. "I felt some of the plants should have been shut down while the analysis was completed, and GE and the utilities didn't want to do that, so I left."

Bridenbaugh said that to the best of his knowledge, the design flaws he had identified were addressed at the Daiichi plant, requiring "a fairly significant expense."

The current problems exist because of the spent fuel rods outside primary containment.
This is a separate issue from the design of the reactor.

 

[skc]

The current problems exist because of the spent fuel rods outside primary containment.
This is a separate issue from the design of the reactor.

Dumping water with helicopters. I hope someone checked that the spent fuel rods are secured from the impact of the water being dropped, not to mention the strength of the spend fuel rod pool structure itself.