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Radiation risk of nuclear power stations in earthquake zones





deanhills
Now that a really bad earthquake has hit Japan, maybe it is a good illustration of the negatives there can be of having a nuclear power station built in an earthquake zone. I would imagine that the nuclear station domes must have been built to the highest construction standards for earthquake zones, but it would appear that it was not enough. Japan is now in a dilemma of a potential nuclear radiation vapours crisis where it has to decide whether it can reduce the pressure of the radiated steam by releasing it, however when it does, that this will obviously be contaminating the environment with nuclear radiation.

Wonder also whether this may have the potential of a Cherbonyl Nuclear type disaster of a few decades ago, in that wind factors could spread this radiation to neighbouring countries and islands as well when it is released to the atmosphere?

I really hope they won't ever consider nuclear stations like these for powering electricity in areas like Los Angeles for example. Shocked
SonLight
The fire is out at the one plant, so the only danger now is the plant that has no backup power to pump water to the overheated reactor. They had provisions for backup power from a nearby source, probably with high priority to insure that its power always went to the nuclear plant if it had any at all. In addition, there were diesel generators on site.

You'd think that would be enough, but apparently the earthquake took out the connection to the other power plant, and the tsunami damaged the diesel generators. One story talked about coolant to be delivered to the plant. they said its probably deuteruim-depleted water. I hope they can get it there and effectively pour it on the fuel rods before they get too hot.
bukaida
Even if it is the heavy water (D2O), it is also not good for human being. The actual nuclear damage is yet to be assesed.
deanhills
bukaida wrote:
The actual nuclear damage is yet to be assesed.
Agreed. And I'm almost certain that they would always rather understate what is going on, than overstate it. So if the alarm has been raised, it really has to be a bad scenario right now.
SonLight
"Japan struggles with nuclear reactors in wake of quake"

http://www.cnn.com/2011/WORLD/asiapcf/03/12/japan.nuclear/

They are working on it. It seems there has been some release of radioactivity, but probably in minor amounts so far. If I understand the situation correctly, only one reactor is still in jeopardy. They plan to use seawater to cool it, which is a difficult and time-consuming procedure. Apparently they have evacuated everyone within 20 kilometers of the plant, and they are calling this the third most serious nuclear accident ever. surpassed only by the devastating Chernobyl accident the the near-miss at Three Mile Island. The article talks about buildings being damaged, apparently part of the containment structure.

I sincerely hope they are able to cool the reactor in time to avoid melting fuel rods and major release of radiation.

Japan seems to have acted responsibly in running the plants, yet the site chosen for them set them up for this kind of problem. They must have been desperate for electricity to build the plant not only in an earthquake zone but also near enough to the ocean to be subject to flooding.
mengshi200
Japan quake: China sets aside disputes, offers help
http://www.washingtonpost.com/wp-dyn/content/article/2011/03/12/AR2011031201428.html
The Chinese defense minister, Liang Guanglie, called his Japanese counterpart, Toshimi Kitazawa, to offer military assets. The Red Cross Society of China pledged 1 million yuan, or about $152,087, to help Japan. Chinese premier Wen Jiabao also had a telephone conversation Friday with Japanese Prime Minister Naoto Kan and offered China's condolences and help.

China's rapid show of sympathy and solidarity toward an Asian neighbor in distress stands in sharp contrast to the heated rhetoric of the past half-year, which saw noisy anti-Japanese demonstrations in some cities and the canceling of some ministry-level exchanges and tour groups.
------------
Ya,Chinese gov. just this time do a right thing !
the-guide
Quote:
The Japanese government has sought to play down fears of a meltdown at Fukushima 1, saying that radiation levels around the stricken plant have now fallen.

But on Sunday morning, Tokyo Electric Power (Tepco) revealed that the cooling system of another reactor had failed.

Government spokesman Yukio Edano said air with some radioactive content was being released to help to cool it.

"We believe that we can stabilise the situation of the reactor," he said.

"And although the air being vented out does contain some minimal radioactive material, however, we believe that it is a minimal level that does not affect human health."


http://www.bbc.co.uk/news/world-asia-pacific-12724953

I've read on the news lastly, an estimated 170,000 people in the 20km radius around the plant #1
have been evacuated and an estimated 30,000 people in the 10km radius around the plant #2 have
been evacuated too.

Hope everything ends well, not worse.

.
.
SonLight
Another update on the nuclear reactor problem:

http://www.washingtonpost.com/wp-dyn/content/article/2011/03/12/AR2011031205493_2.html?hpid=topnews&sid=ST2011031100651

It is clearly very serious. Public health has already been affected, though on a small sccale at the moment. They have evacuated the vicinity of the reactor. Apparently they expect the seawater to destroy the reactor but at this point care only about safety. The reactors having trouble are old design and at the end of their design life. I sincerely hope they can prevent venting of a large amount of radiation.
deanhills
Looks as though there have been people who have been exposed to the radiation, but considering the magnitude of relocating 200,000 people, 141 sounds like a small number? If correct? Would there have been people around when No. 1 reactor exploded?

Quote:
Nuclear officials here at Fukushima shut down three reactors after the tsunami on Friday, but an explosion tore through the No. 1 reactor building on Saturday.

When the cooling system on the No. 3 reactor also began to fail Sunday, workers pumped seawater and boron into it. Yukio Edano, the government’s chief cabinet secretary, warned Sunday of the possibility of an explosion at No. 3 — and the chance of meltdowns at both reactors.

More than 200,000 people were evacuated from danger zones around two atomic facilities in Fukushima. Japanese officials reported that 19 people showed signs of radiation exposure and as many as another 141 were feared to have been exposed, including some who had been outside the plant waiting to be evacuated. . Three workers are suffering from full-on radiation sickness.

Source: New York Times
Bluedoll
SonLight wrote:
Another update on the nuclear reactor problem:

http://www.washingtonpost.com/wp-dyn/content/article/2011/03/12/AR2011031205493_2.html?hpid=topnews&sid=ST2011031100651

It is clearly very serious. Public health has already been affected, though on a small sccale at the moment. They have evacuated the vicinity of the reactor. Apparently they expect the seawater to destroy the reactor but at this point care only about safety. The reactors having trouble are old design and at the end of their design life. I sincerely hope they can prevent venting of a large amount of radiation.
You know it is amazing how we get so much information off the media some of which is not that informative. For example, I heard one news reporter state that Japan got hit with a ‘double whammy”. They got an earth quake and a large wave. I can only assume unless someone tells me different that the wave was caused by the earth quake? Some times I find the media rather misleading.

So thank you all for this post.
In any event, I have to admit I am not fully educated to nuclear plant construction .

I’m wondering why they can not pull the material and then isolate it rather than just try to cool it down. In other words quickly take the plant apart now? Not to attempt to do so because of economics and to keep the thing running in the future could result in a far greater cost? Perhaps, this course of action is now old news and should have been done immediately or maybe it is not that simple? - does anyone understand these reactors?
deanhills
Bluedoll wrote:
I’m wondering why they can not pull the material and then isolate it rather than just try to cool it down. In other words quickly take the plant apart now? Not to attempt to do so because of economics and to keep the thing running in the future could result in a far greater cost? Perhaps, this course of action is now old news and should have been done immediately or maybe it is not that simple? - does anyone understand these reactors?
My understanding is that all their various attempts are in order to get the mechanicals are all out of control. Engineers are working it in order to get control of the mechanical engineering side of things. When they have managed to get control of the equipment, they will probably be able to do what you think the logical thing is to do. But before they get it under control, there isn't a simple "off switch" anywhere that they can push to power things down.
Bluedoll
deanhills wrote:
Bluedoll wrote:
I’m wondering why they can not pull the material and then isolate it rather than just try to cool it down. In other words quickly take the plant apart now? Not to attempt to do so because of economics and to keep the thing running in the future could result in a far greater cost? Perhaps, this course of action is now old news and should have been done immediately or maybe it is not that simple? - does anyone understand these reactors?
My understanding is that all their various attempts are in order to get the mechanicals are all out of control. Engineers are working it in order to get control of the mechanical engineering side of things. When they have managed to get control of the equipment, they will probably be able to do what you think the logical thing is to do. But before they get it under control, there isn't a simple "off switch" anywhere that they can push to power things down.
Thanks, I understand more now. Well all this time I thought that all the engineers and scientists in the world had everything under control.
deanhills
Bluedoll wrote:
Well all this time I thought that all the engineers and scientists in the world had everything under control.
Obviously they still have to practice a lot to get earthquakes and tsunamis under control. Laughing

Since writing my last comment on your posting, I learned that the problem was really one of keeping the rods under water so that they won't melt down. The pump stations that are supposed to cool the rods were damaged during the earthquake and then destroyed during the tsunami. On top of that they don't have enough energy to pump the water, so have to work on non-traditional type engineering innovations to keep the rods immersed in water. As soon as the rods get to be exposed, then danger of radiation is real. They are now even trying to throw water from helicopters or using high-pressure water hoses to keep the water levels up. I can just imagine real heroic feats going on as those working in the front lines to keep the rods immersed in water must be exposed to radiation.
c'tair
The thing is, as deanhills pointed out, it's not easy to stop a reaction once it's been started. If I'm correct, the current temperature of the rods, even though they have been withdrawn, is still around 2000 degrees Celsius and the only way to cool them is to use some sort of fluid, but even that will take a while. That's almost half the temperature of the sun to put it into perspective.

We must also look at this from the safety perspective. Chernobyl was a disaster based on bad engineering. The reactors in Japan got hit with and earthquake AND a tsunami. I'm not how many thing would be able to withstand that sort of barrage from nature, but only the water pumps were damaged. The reactors themselves were not breached, which is a miracle of modern design and ingenuity.

Imagine what would happen if the reactors themselves were breached and radioactive rods with temps as high as 2000 deg. C were hit with sea water? I can only imagine that the water would instantly turn into steam and become irradiated and then spread around the area, then the rods themselves may splinter due to the heat exchange, this nuclear dust would then be blown to the atmosphere. Oh, and the pressure involved in thousands of liters of water turning into steam? A truly apocalyptic vision and I think we have the builders and scientists behind nuclear power plants to thank for all the safety features.
deanhills
c'tair wrote:
I think we have the builders and scientists behind nuclear power plants to thank for all the safety features.
Well said. Wish the media could pick up on this as well. This is not Chernobyl at all. This is responsible engineering. And you're right. It could have been much worse, but was not, as those reactors must have been built to very high standards. I am keeping my fingers crossed as I really want those guys to succeed. I'm almost certain they have the must savvy of engineering consultants around to finesse ways of keeping those rods submerged in water. Would be great if they could have done something with the energy coming from those rods however. What an awesome waste that must be!
jwellsy
Chernobal was not an engineering issue. The management came up with a hair brained idea for a test and nobody dared to question them. What Chernobal put out instantaneously Japan may release 3 times as much only spread out over a month, most of which will fall into the ocean.

The whole sea water injection thing is something they did right. On a loss of all AC electrical power you have to maintain reactor pressure as high as possible manually using Safety Relief Valves to bleed off the energy from decay heat of the fission product daughters inside the fuel pins/bundles. If you let pressure get too low then your wasting water inventory and the level decrease will accelerate. So for the first 48 hrs your just buying time to get something lined up with flooding quantities of water capacity before water level reaches the top of the active fuel. During this time they rotate either a spool piece or a blank flange to line up the fire protection system to the vessel. They probably have a diesel driven fire pump to supply the sea water. The problem is that a diesel driven fire pump only puts out ~100psi yet the reactor will be ~600psi. So what happens is that as water level drops you get as many low pressure sources lined up as possible. Then when level reaches the top of active fuel you open all safety relief valves to rapidly pressurize the reactor so the low pressure systems can inject.
jwellsy
Where they have screwed the pooch is a lack of effective hydrogen mitigation strategies. I have not read any reports yet of any hydrogen mitigation strategies being attempted that are required in the U.S. plants. That's why they have had the huge explosions.

I have many serious questions for the engineering dept, management team and state officials. Mainly why did they not provide what the operators needed during that first 48 hours. They could have helicopter air lifted in locomotive size package diesel generator sets and pumper fire trucks. And why were there no effective hydrogen mitigation strategies in place prior to the event, such as hydrogen igniters and recombiners?
deanhills
jwellsy wrote:
I have many serious questions for the engineering dept, management team and state officials. Mainly why did they not provide what the operators needed during that first 48 hours. They could have helicopter air lifted in locomotive size package diesel generator sets and pumper fire trucks. And why were there no effective hydrogen mitigation strategies in place prior to the event, such as hydrogen igniters and recombiners?
Wish we could ship you to Japan jwellsy, those are excellent questions now that you mention them. Very Happy
Navigator
UPDATE:

Quote:
Washington - The chairman of the United States Nuclear Regulatory Commission gave a significantly bleaker appraisal of the threat posed by Japan's nuclear crisis than the Japanese government, saying on Wednesday that the damage at one crippled reactor was much more serious than Japanese officials had acknowledged and advising to Americans to evacuate a wider area around the plant than the perimeter established by Japan. Japanese television showed what appeared to be steam rising from reactor No. 3 at the Fukushima Daiichi plant about 10 a.m. Wednesday.

The announcement marked a new and ominous chapter in the five-day long effort by Japanese engineers to bring four side-by-side reactors under control after their cooling systems were knocked out by an earthquake and tsunami last Friday. It also suggested a serious split between Washington and Tokyo, after American officials concluded that the Japanese warnings were insufficient, and that, deliberately or not, they had understated the potential threat of what is taking place inside the nuclear facility.

Gregory Jaczko, the chairman of the commission, said in Congressional testimony that the commission believed that all the water in the spent fuel pool at the No. 4 reactor of the Fukushima Daiichi Nuclear Power Station had boiled dry, leaving fuel rods stored there exposed and bleeding radiation. As a result, he said, "We believe that radiation levels are extremely high, which could possibly impact the ability to take corrective measures." If his analysis is accurate and Japanese workers have been unable to keep the spent fuel at that inoperative reactor properly cooled - it needs to remain covered with water at all times - radiation levels could make it difficult not only to fix the problem at reactor No. 4, but to keep workers at the Daiichi complex from servicing any of the other problem reactors at the plant. Mr. Jaczko (the name is pronounced YAZZ-koe) said radiation levels may make it impossible to continue what he called the "backup backup" cooling functions that have so far helped check the fuel melting at the other reactors. Those efforts consist of using fire hoses to dump water on overheated fuel and then letting the radioactive steam vent into the atmosphere. Those emergency measures, implemented by a small squad of workers and firemen, are the main steps Japan is taking at Daiichi to forestall a full blown fuel meltdown that would lead to much higher releases of radioactive material. Mr. Jaczko's testimony came as the American Embassy in Tokyo, on advice from the Nuclear Regulatory Commission, told Americans to evacuate a radius of "approximately 50 miles" from the Fukushima plant. The advice represents a graver assessment of the risk in the immediate vicinity of Daiichi than the warnings made by the Japanese themselves, who have told everyone within 20 kilometers, about 12 miles, to evacuate, and those between 20 and 30 kilometers to take shelter. Mr. Jaczko's testimony, the most extended comments by a senior American official on Japan's nuclear disaster, described what amounts to an agonizing choice for Japanese authorities: Send a small number of workers into an increasingly radioactive area in a last-ditch effort to cover the spent fuel, and the fuel in other reactors, - with water, or do more to protect the workers but risk letting the pools of water protecting the fuel boil away - and thus risk a broader meltdown.

The Japanese authorities have never been as specific as Mr. Jascko was in his testimony about the situation at reactor No. 4, where they have been battling fires for more than 24 hours. It is possible the authorities there disagree with Mr. Jascko's conclusion about the exposure of the spent fuel, or that they have chosen not to discuss the matter for fear of panicking people. Experts say workers at the plant probably could not approach a fuel pool that was dry, because radiation levels would be so high. In a normally operating pool, the water provides not only cooling but also shields workers from gamma radiation. A plan to dump water into the pool, and others like it, from helicopters was suspended because the crews would be flying right into a radioactive plume.


http://www.sott.net/articles/show/225937-U-S-Calls-Radiation-Extremely-High-and-Urges-Deeper-Caution-in-Japan
jwellsy
Quote:
Wish we could ship you to Japan jwellsy, those are excellent questions now that you mention them. Very Happy


Actually, I am on an International Atomic Energy Agency volunteer list to do that. But with Americans being evacuated from Japan, I may have to report to Vienna.

Plus, I had a meeting today about starting a team to do a Fukushima Daiici Hydrogen Mitigation Failure Analysis in conjunction with a Big 10 University. I set up the meeting and may wind up being the project manager on it if we move forward with it.

This is all I've been able to think about the past several days. I've had this scenario run on me in a nuclear control room simulator several hundred times over the years. Every time it's emotionally devastating. Those 50 operators left there will never be the same after living through the real thing.

I am being called by a higher power to help understand what went wrong. It didn't have to come to all this.
deanhills
jwellsy wrote:
Quote:
Wish we could ship you to Japan jwellsy, those are excellent questions now that you mention them. Very Happy


Actually, I am on an International Atomic Energy Agency volunteer list to do that. But with Americans being evacuated from Japan, I may have to report to Vienna.
If it is as serious as it is, and apparently it is, then I withdraw what I said, I'd hate for you to be shipped there. I always thought the Japanese were much more savvy than that. What is common sense to an expert like you would also have been common sense to the Japanese nuclear reactor experts. Something most have gone seriously wrong for them not to have followed the logical steps you mentioned. Quite amazing that the chairman of the United States Nuclear Regulatory Commission report (refer Navigator's posting above) should appear just after you listed your concerns.
webpinoy
Nuclear power plants must be 100 %safe. But there is no 100 %. So what is the conclusion? Don't build it! I know we have high energy demands and we don't like to pay much. We can not just shut down all the nuclear power plants right now.

But what can we do?
We can stop to build new nuclear power plants.
We can invest in development of alternate energy.
That will help to shut down the nuclear power plants in maybe 15 or 20 years from now.

Even if we shut down, we still will have to deal with the radioactive waste from this plants.

But at least, we could look into the eyes of our children and say that we went to a good way.

Or we go on like nothing happens and continue to destroy our planet.
deanhills
webpinoy wrote:
But what can we do?
More funds have to be invested in research for alternative energy resources that are less harmful to the environment. I'm sure there must be projects that are already viable, but lack the funds for further development. Who knows, after the disaster in Japan, people will pay more attention to alternatives.
c'tair
The problem with alternative is that they are high priced and low output. For example, the materials used in the production of wind turbines or solar panels are highly toxic in themselves and their manufacturing process isn't the best either. If we could just churn them out and put them anywhere than bam, problem solved, but no, we cannot just produce millions of turbines or solar panels - their efficiency is low, they destroy the land where they are at (noise pollution anyone?) etc.

Remember that most powerplants are really old by now, since no new ones have been built. Fukushima was built in 1971 or 40 years ago! And that 40 year old tech was able to withstand and earthquake and a tsunami.

In France, nuclear power plants provide about 78% of all power. There are 59 plants in total. Why aren't we hearing about explosions and mutant babies being born in France? Because nuclear power is safe as long as it's well maintained and not hit by a natural disaster. Add to that the fact that research is still going on, and I remember hearing about wonderful thorium based reactors that do not out put almost any nuclear waste when compared to modern reactors.

To summarize, nuclear power is the way to go, since it is cheap and safe. If someone, like webpinoy, is going to make a claim about the danger of nuclear power plants then please include some good arguments in favor instead of "So what is the conclusion? Don't build it!". Webpinoy - did you know that millions of people die in car crashed per year? Would you also tell people "dont build cars!"?
deanhills
c'tair wrote:
The problem with alternative is that they are high priced and low output. For example, the materials used in the production of wind turbines or solar panels are highly toxic in themselves and their manufacturing process isn't the best either.
I wasn't thinking of those. I was thinking more along the lines of more advanced development of fusion or geothermal energy systems or fuel cells, or possibly projects that we don't even know about, as there have not been funds available for them to be developed.
Navigator
UPDATE:

Quote:
Japanese authorities: We have no control over the Fukushima Nuclear plant, people will probably die from fallout

Officials admit they may have to bury reactors under concrete - as happened at Chernobyl Government says it was overwhelmed by the scale of twin disasters Japanese upgrade accident from level four to five - the same as Three Mile Island We will rebuild from scratch says Japanese prime minister Particles spewed from wrecked Fukushima power station arrive in California Military trucks tackle reactors with tons of water for second day.

The boss of the company behind the devastated Japanese nuclear reactor today broke down in tears - as his country finally acknowledged the radiation spewing from the over-heating reactors and fuel rods was enough to kill some citizens Japan's Nuclear and Industrial Safety Agency admitted that the disaster was a level 5, which is classified as a crisis causing 'several radiation deaths' by the UN International Atomic Energy. Officials said the rating was raised after they realised the full extent of the radiation leaking from the plant. They also said that 3 per cent of the fuel in three of the reactors at the Fukushima plant had been severely damaged, suggesting those reactor cores have partially melted down.

After Tokyo Electric Power Company Managing Director Akio Komiri cried as he left a conference to brief journalists on the situation at Fukushima, a senior Japanese minister also admitted that the country was overwhelmed by the scale of the tsunami and nuclear crisis. He said officials should have admitted earlier how serious the radiation leaks were.


http://www.sott.net/articles/show/226028-Japanese-authorities-We-have-no-control-over-the-Fukushima-Nuclear-plant-people-will-probably-die-from-fallout
ocalhoun
webpinoy wrote:

But what can we do?
We can stop to build new nuclear power plants.
We can invest in development of alternate energy.
That will help to shut down the nuclear power plants in maybe 15 or 20 years from now.


Nuclear power is alternate energy.
As pointed out above, wind or solar energy would be far too expensive, might not even be possible at a large enough scale, and they have environmental problems of their own.

You've got three viable options for the next few decades:
1- Cut back on energy usage massively -- not little savings here and there, actually removing it from people who 'need' it.
2- Build fossil fuel plants
3- Build nuclear plants

Modern nuclear plants are the safest, cleanest viable energy source we have. Don't throw that away because an antiquated design failed to survive an earthquake that surpassed its design parameters and a tsunami.

(Now, should the more antiquated nuclear plants be either retired or upgraded? Yes.)
deanhills
ocalhoun wrote:
Modern nuclear plants are the safest, cleanest viable energy source we have. Don't throw that away because an antiquated design failed to survive an earthquake that surpassed its design parameters and a tsunami.

(Now, should the more antiquated nuclear plants be either retired or upgraded? Yes.)
Well said Ocalhoun, and I support that 100%. I'm not one for regulations, but since nuclear reactors can impact neighbouring countries, I believe that there should be tough regulations on everyone internationally, and regular inspections. There should also be tougher regulations for reactors that are built in earthquake zones, and if anything should happen to those reactors, there should be a prescribed step by step way of dealing with the emergency on an international basis. For example there should always be a standby team of international experts that can step in and take charge on the double. There has been a lot of criticism how the Japanese dealt with the crisis, common sense steps that could have been followed immediately after the catastrophe struck (refer jwellsy's posts), and a crisis that has been understated as well. If an international team of nuclear reactor experts could have been shipped out, this could have made a great difference.
jwellsy
I just saw a video clip of them using a fire truck finally pumping water into the plant. Better late than never I guess.
deanhills
jwellsy wrote:
I just saw a video clip of them using a fire truck finally pumping water into the plant. Better late than never I guess.
What is your take on them dumping water with a helicopter? I don't know much about nuclear reactors, but I would have thought pumping would have been more ideal for cooling of the rods, which they seem to have finally achieved? Also, what is the progress with regard to fixing the pump stations? Do you think there is still a chance to save the nuclear reactors?
jwellsy
deanhills wrote:
What is your take on them dumping water with a helicopter? I don't know much about nuclear reactors, but I would have thought pumping would have been more ideal for cooling of the rods, which they seem to have finally achieved? Also, what is the progress with regard to fixing the pump stations? Do you think there is still a chance to save the nuclear reactors?


Helicopters are fine if your trying to cover a large area like in a forest fire. Spent fuel pools are pretty small about 50ft x 50ft. Trying to hit a target like that on a fly by from 500 ft up through twisted metal wreckage is pretty much a joke.

Things are yet to be determined about getting the pumps running. Even though they have strung a Km of cable, there's lots of different interlocks, permissives, and trips in the pump control logics that will probably have to be bypassed or overridden to satisfy the starting logic. Those are some very powerful pumps that can easily damage downstream pipe if the pipes or pipe hangers are degraded or damaged.

Save the cores? From what? They will never operate again or be recycled. They are a pile of melted trash now. The bottom of BWR is not like the smooth bottoms of a PWR. In a BWR the control rods go in and out the bottom of the reactor. So, all those control rod drive mechanisms should help hold back or disperse any kind of pyroclastese flow that may breach the bottom head.

The chance of criticality is pretty much non existent. BWR's have negative void and temperature coefficients of reactivity. That means that as temperature increases reactivity decreases and as boiling occurs the reactivity decreases even faster.
deanhills
jwellsy wrote:
The chance of criticality is pretty much non existent. BWR's have negative void and temperature coefficients of reactivity. That means that as temperature increases reactivity decreases and as boiling occurs the reactivity decreases even faster.
Sounds pretty hopeless then. Would you have thought that the concrete and sand method would have been better, i.e. that those reactors are a write-off anyway, so they may just as well scratch them as soon as possible? If they do scratch them with concrete and sand, would that get rid of the radiation problem completely, and would it mean that they may never be able to use that land for other activities? Like with Chernobyl?
Quote:
The worst of the radioactive debris was collected inside what was left of the reactor, much of it shoveled in by liquidators wearing heavy protective gear (dubbed "bio-robots" by the military); these workers could only spend a maximum of 40 seconds at a time working on the rooftops of the surrounding buildings because of the extremely high doses of radiation given off by the blocks of graphite and other debris. The reactor itself was covered with bags containing sand, lead, and boric acid dropped from helicopters (some 5,000 metric tons during the week following the accident). By December 1986 a large concrete sarcophagus had been erected, to seal off the reactor and its contents.

Source: Wikipedia

Looks as though the Chernobyl situation will never be resolved, only contained?
Quote:
The massive concrete and steel "Sarcophagus", quickly constructed using "arms length" methods, has deteriorated over the years, creating a potentially hazardous situation. Several repairs were made to the current shelter, including the stabilisation of the ventilation stack and reinforcement of the roof. In addition, a plan for the construction of a more secure and permanent structure to be built around the existing Sarcophagus was drafted; work has already begun on the infrastructure of this new shelter.

Source: IAEA.org
jwellsy
Quote:
Japanese workers were forced Monday to evacuate from the crippled Fukushima nuclear power plant after dark smoke rose from one of the facility's six reactors.

Officials said that there had been no immediate increase in radiation levels and the cause of the smoke was under investigation.

The plant's operator, Tokyo Electric Power Company, says abnormally high levels of radioactive substances have been found in the Pacific Ocean along Japan's northeastern coast. But they are not considered a threat to human health.

http://www.voanews.com/english/news/asia/east-pacific/Workers-Evacuated-as-Smoke-Rises-From-Japanese-Nuclear-Plant-118350314.html

They are claiming that diesel generators have been hooked up to 3 of the 6 plants. But, that's a long way from the event being stabilized. The diesel will power up a 4160 volt buss that powers
- a residual heat removal (RHR) pump that circulates water through the core,
- a fuel pool cooling and cleanup (FC) pump,
- a shutdown cooling water pump that circulates seawater through big heat exchangers to cool the RHR & FC systems,
- a 480 volt motor control center that supplies:
-- a small water leg pump that keeps the RHR system full to prevent a dangerous water hammer on pump starts.
-- and all the motor operated valves.

They have to do an extensive valve lineup, get the waterleg pump running, fill the system with water and vent off all trapped air on the RHR system before attempting a main pump start.

It's not unusual to do this in a high radiation area >100 mrem/hour. However these guys are probably dealing with radiation levels that would normally exclude entry >1rem/hour.

This whole process is slowed way down with evacuating the site routinely. It sounds like they haven't even started this process on 3 units.

I can't believe the Japanese government doesn't step in and take control of directing activities. The only things these units will ever be good for is research. How long is it going to take them to admit defeat and go the Chernobyl option? The sooner they seal it from the environment the better.
deanhills
jwellsy wrote:
I can't believe the Japanese government doesn't step in and take control of directing activities. The only things these units will ever be good for is research. How long is it going to take them to admit defeat and go the Chernobyl option? The sooner they seal it from the environment the better.
I would have thought that the members of the IAEA would have stepped in as well by now. Isn't Japan under some contract agreement with regard to its operation of Nuclear Reactors with the IAEA? I must say, when emergencies strike in the world, such as in Libya, the world seems to be dithering BIG time.
fate_merchant
ocalhoun wrote:

Modern nuclear plants are the safest, cleanest viable energy source we have.


Not true. Nuke plants don't exist in a vacuum. Mining uranium ore is a toxic mess. The dust from the tailings blows around and is directly connected to high cancer rates. This has been happening for years in Navajo Nation, as well as in the Black Hills area of South Dakota. It happens everywhere uranium is mined.

Nuke plants are also heavily dependent on fossil fuels at every step of the process - mining, of course, shipping, and also refining. So this just gets more expensive all the time, while it also exacerbates the carbon emissions problem associated with global warming.

And then there's the problem of what do do with the toxic wastes. That still hasn't been solved to everybody's satisfaction, and it never will be.

One thing the US has figured out is that depleted uranium from used fuel rods makes for excellent weapon tips. Unfortunately for the people who happen to live in the areas where these weapons are used, these weapon tips turn into a kind of aerosol of very fine dust particles. People then breathe this dust and get cancer. About 365 tons of this stuff from the early Gulf War has been blowing around southern Iraq for almost 20 years now, the result of which is horrible birth defects amongst the Shia Iraqis in that Basra area.

This also happened in Kosovo, and is now happening in Afghanistan and Libya. Depleted uranium has been additionally detected on the Big Island in Hawaii due to illegal weapons practice on a base there. All this information is online for anyone who wants to read more.

The saddest thing about all this poisoning of land. air, and water is that we have the technology to enable us to completely decentralize the production of electricity. Individual homes are capable of producing more energy than they need. Those homes which do so and are still hooked into the grid can make the electric meter run backwards, and the power companies will pay households for this energy. People are really doing this as I write, and some have been doing it for decades.

The main reason this technology is not widely available is because the corporate power companies want to keep us dependent.

This brings up the money issue, and nuclear energy is the most expensive energy ever produced. This cost is passed on to the consumers. In fact, if nuke plants were not subsidized by the government in the US, in other words, by the taxpayers, they would not be able to stay in business due to the astronomical overhead involved in keeping these things running.

We need to shut this industry down and invest our money where it counts.
deanhills
fate_merchant wrote:
ocalhoun wrote:

Modern nuclear plants are the safest, cleanest viable energy source we have.


Not true. Nuke plants don't exist in a vacuum. Mining uranium ore is a toxic mess. The dust from the tailings blows around and is directly connected to high cancer rates. This has been happening for years in Navajo Nation, as well as in the Black Hills area of South Dakota. It happens everywhere uranium is mined.
Good point. There is an enormous mine near Swakopmund in Namibia, and what you say is true about cancer rates. I've forgotten about that however, so good you are reminding us that uranium in its raw form can also be harmful to humans.
Quote:
Normal functioning of the kidney, brain, liver, heart, and other systems can be affected by uranium exposure, because, besides being weakly radioactive, uranium is a toxic metal.

Source: Wikipedia
jwellsy
I don't know how to embed nonyoutube videos. But, here's a pretty good video of Michio Kaku.

http://cnn.com/video/?/video/bestoftv/2011/05/31/exp.arena.japan.nuclear.melt.cnn

Michio Kaku was a bit dramatic, but fairly accurate.

One thing he is absolutely wrong about is that nuc plants are designed to inject sea water or lake water into the reactor using the Fire Suppression system piped into the Residual Heat Removal Systems. That line is normally blank flanged off or has a spool-piece that has to be rotated to prevent any accidental use of that line. U.S. plants even test that line is clear about every other refuel cycle.

The material selections in a core are not evaluated for operating with dirty water. But, accident mitigation is most certainly designed into the piping systems to use whatever water you can find to shove in there.

Once water level drops below the top of active fuel in a hot core, it's done. You have just trashed it beyond ever being useful again.

It makes my head explode that they continue to have an uncontrolled release to the environment by flushing fission fragments into the sea with no end in site. I wish they would build a great big sea jetty wall around it to contain the fission fragments.

Chernobyl was whole different scenario where the automatic reactor protection was intentionally bypassed/disabled so they could perform a test to see how many extra megawatts they could get out of their generator from rotational inertia following a turbine trip. In that case the control rods were prevented from shutting down the reactor, which led to a huge steam explosion when cold water was pumped into it to control level. When a turbine trips you also lose feedwater heating.

The thing that really helped Fukashima was that their automatic reactor protective systems appear to have worked as designed and inserted the control rods to shut down the reactors.

What really tubed them was failure to mitigate hydrogen production. This was avoidable. U.S. licensed operators have a requal exam and train in full scale control room simulators every month, plus have intense annual requal written and simulator exams. These types of accident scenarios get practiced many many times until it is second nature on what to do, and hydrogen mitigation is a key aspect of what to do when everything else has gone wrong.
deanhills
@jwellsy What do you think the environmental impact will be on the ocean and do you think it will make its way to the US coast line?
jwellsy
Japan has not been very honest or transparent in it's reporting to date so I doubt they will ever give an honest accounting of the total curries released to the environment. Their stance from the beginning has been that the release of I131 is only about 10% of what Chernobyl was, which would be about 50 million curries of I131 and it's precursors. They are not even talking about how many curries of uranium, plutonium and a long list of other elements that have been lost.


Here's a few studies about the impact of Chernobyl.
Quote:
A report of the International Atomic Energy Agency,[7] examines the environmental consequences of the accident. Estimates of the number of deaths potentially resulting from the accident vary enormously: Thirty one deaths are directly attributed to the accident, all among the reactor staff and emergency workers.[9] A UNSCEAR report places the total confirmed deaths from radiation at 64 as of 2008. The World Health Organization (WHO) suggests it could reach 4,000.[10] A 2006 report predicted 30,000 to 60,000 cancer deaths as a result of Chernobyl fallout.[11] A Greenpeace report puts this figure at 200,000 or more.[12] A Russian publication, Chernobyl, concludes that 985,000 excess deaths occurred between 1986 and 2004 as a result of radioactive contamination.[13]

http://en.wikipedia.org/wiki/Chernobyl_disaster

Low levels of I131 have already reached most states in the US due to the atmospheric fallout footprint.

The impact of the release into the ocean should be able to be modeled in a supercomputer visualization lab. The heaviest elements will settle out closer to the plant than lighter elements almost like concentric deposit zones being disturbed by temperature movements, fish and marine mammal migrations etc.

I'll post some cool pics in a different post to minimize some crazy scrolling.
jwellsy
enjoy

Edit: these pics are so large they screw up the formatting of the whole thread. You can open them yourself.

http://avl-test.ncsa.illinois.edu/wp-content/uploads/2010/03/NCSA_mbari06over3840.jpg


http://avl-test.ncsa.illinois.edu/wp-content/uploads/2010/03/ROMStempHDstill.0660.jpg


http://avl.ncsa.illinois.edu/project-archive/keeping-current-with-ocean-science
deanhills
You're right jwellsy. They are amazing photos, particularly the first one. Really sad about the marine life, probably going to affect fishery as well, the Japanese are probably going to be even more aggressive in fishing international waters than they have been before.
jwellsy
Actually, those are still frames out of a High Definition 3D video in 4K resolution format. They like to project it onto a 12 foot wide and 8 foot tall screen. Watching it on a couch about 8 foot away from wearing opposing polarized glasses. The 3D effect is like nothing else I've ever seen. It makes you dodge and duck the images coming at you or whizzing past your head. They only disappear when they get to about arms length from you.

If you ever see an ad for a Visualization Lab Demonstration, go check it out.
deanhills
jwellsy wrote:
If you ever see an ad for a Visualization Lab Demonstration, go check it out.
I most certainly will. Thanks for giving us a heads up. Very Happy
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