FUKUSHIMA earthquake and tsunami thread and aftermath

[corevalue]

Good post Chumpus. One thing troubles me. The reactor temperature is way over it's operating point, as they have declared a risk of meltdown. That increases the backpressure the water injection pumps must handle. At what point do they have to vent steam to reduce pressure to a point the pumps can inject more water, and where is the exhaust water/steam taken to?

[Scott Sando]

Because the joke is that you actually think you know what is going on.

Please carry on.

And the other people do know whats going on.

[Damik]

To be honest, I didn't get your point. When the reactor is operating, the core would be much cooler than during a meltdown. A meltdown by definition, occurs when the core gets too hot.

Based on the maximum reactor power of 500 MW you can calculate how much energy is available in the reactor, when it shuts down.

The core will spend this energy to vaporise the coolant, melt the reactor steel and to burn through the containment. The energy is also lost by the heat transfer.

If the containment is thick enough there is not enough energy to melt through.

Plus you build this thing often on a solid rock ...

[DeepLurker]

I see your point. But I assume that if you build a nuclear power station close the Krakatoa the Krakatoa will kill more people anyway, no ????

You're missing the point: you claimed that it was possible to make a reactor that could withstand any earthquake, which implies that there is an upper limit to the energy released in an earthquake.

I queried that, and you gave a cryptic reply about 9.81m/s, which suggests that you see a reactor falling down a hole as the only way an earthquake can damage said reactor. You need to thing more outside-the-box, as it's easy to come up with lots of other ways in which an earthquake can crush any man-made object

[fellow]

Exactly. And that's the problem. Although the main nuclear reaction has been stopped, other decay reactions continue and the reactor fuel continues to produce heat. Unless the reactor is cooled, the water in it will eventually boil. Which is exactly what happened, steam was released into the containment building. So there are 2 problems: water in the reactor going down, and steam pressure in the building going up.

The concern is that if the water level dropped and exposed the fuel that the fuel would melt. That probably has happened, as hydrogen was produced - which would imply that the fuel had nearly reached melting temperature - as hydrogen doesn't get produced at normal temperatures.

The first problem was the water supply. The reactor is at huge pressure, so fresh water has to be pumped with enormous pumps, requiring copious amounts of electricity (or a battery controlled steam powered pump). These both failed at some point.

However, later there was another problem - so much steam had been released into the containment building (the battery/steam system can only top up the reactor - it can't circulate the water through radiators to stop it boiling), that the actual temperature and pressure in the building were reaching the building limits (some reports claim that the pressure and temperatures in the reactor building were considerably higher than a typical pressure cooker - anything up to 150 C and 3 atmospheres of pressure). The problem was that the steam in the reactor building was mildly radioactive.

After a lot of debate, the decision was made to open the vents in the building and release the radioactive steam to prevent the containment cracking under the pressure. Apparently, some hydrogen was also released from the containment building, which got into the space between the containment and the outer skin - this ignited and blew the outer walls and roof off.

It will be pressurised - the reactor's pressure in this design is 1100 psi, so the pumps will have to pump harder than that to get the cold water in.

The idea is to keep pumping as long as the reactor needs topping up because water is boiling off from the heat (weeks before the heat production drops to easily manageable levels), or until the main circulation/cooling pumps can be restarted.

The water being pumped also contains boron which interferes with the nuclear fission reactions. The shutdown rods contain boron which is what keeps the reactor shut down. The concern, if the fuel has melted is that if it pools at the bottom of the reactor (out of reach of the shutdown rods) the reactions could restart, and the amount of heat that needs removal becomes an even bigger problem. The boron should stop the reactions from restarting.

Good post. Damik needs to read this before he makes another post.

[corevalue]

Based on the maximum reactor power of 500 MW you can calculate how much energy is available in the reactor, when it shuts down.

The core will spend this energy to vaporise the coolant, melt the reactor steel and to burn through the containment. The energy is also lost by the heat transfer.

If the containment is thick enough there is not enough energy to melt through.

Plus you build this thing often on a solid rock ...

Or on mud, like Sizewell

[billybong]

HOLY SH**........

Look at these monitors:

http://i677.photobucket.com/albums/vv131/electroweak/japmon.jpg

compared to these...

http://i677.photobucket.com/albums/vv131/electroweak/onagawa.jpg

Notice in the first AND the second the units are nGy/hr.

(see list in image 1, and top left of image 2)

Now notice Image 1 over all japan they are 20-80 nGy/hr.

Image 2 at the Onagawa plant we have 7400 nGy/hr

You can see this for yourself at:

http://www.bousai.ne.jp/eng/index.html

and

http://www.tohoku-epco.co.jp/electr/genshi/onagawa/mp.html

ARE WE BEING LIED TO????

If the Hokkaido monitoring site is ahowing high radiation then the fallout has already travelled at least 500 - 600 miles North of Fukushima.

[bogbrush]

And the other people do know whats going on.

I've heard a few people give information without speculating and pronouncing verdicts based on little information.

I tend to like that approach.

Edited March 13, 2011 by bogbrush

[Scott Sando]

If the Hokkaido monitoring site is ahowing high radiation then the fallout has already travelled at least 500 - 600 miles North of Fukushima.

Its ok, don't the Japanese know, radiation is as good for you as a brisk walk in the country.

[mdman]

BTW the explosion did NOT cause the release of any radioactivity. It was a hydrogen explosion from outside the reactor. Any radioactive material that has been released has been from venting of steam from the reactor.

I don't find the explanation of the authorities credible. They are the ones blaming the rise on an event 150 miles away. If they're correct, we'd expect much higher readings closer to the blast site and along the line connecting the two power plants (but there are no reports of that).

[_w_]

Well since the whole thread is such a joke I thought so too. Thanks!

All I see in this thread are people with varying degrees of expertise (or lack of) trying to express their understanding of the situation. It may not be pretty but it looks to me like a natural reaction to shocking events such as those that occurred in Japan. Not only that but I for one am very grateful to those who do bother to share their knowledge, people you mock for taking the time to enlighten those without.

Perhaps the joke on you for painting such a silly image of yourself in this thread?

[Scott Sando]

I've heard a few people give information without speculating and pronouncing verdicts based on little information.

I tend to like that approach.

Balls of course they were speculating.

[ChumpusRex]

Good post Chumpus. One thing troubles me. The reactor temperature is way over it's operating point, as they have declared a risk of meltdown. That increases the backpressure the water injection pumps must handle. At what point do they have to vent steam to reduce pressure to a point the pumps can inject more water, and where is the exhaust water/steam taken to?

The reactor has pressure relief valves that automatically open at a preset pressure - around 1100 - 1200 psi on this particular type of reactor. Because the steam will be slightly radioactive, the steam is vented into the containment building. The injection pumps will be designed to cope against the maximum design pressure of the reactor.

To prevent the containment building blowing up from steam pressure. The steam doesn't just go into the air - but is released into a series of cold water 'surge' tanks surrounding the reactor within the containment building. These cool the steam and condense it back into water and prevent a pressure surge in the containment. This works fine for a number of hours, until the water in the the surge tanks boils. At that point, temperatures and pressures in the containment start rising dramatically. Under normal circumstances, there would be emergency reactor cooling systems that dump the heat outside the containment preventing the reactor venting into containment - and even if those failed, there would normally be containment cooling systems to keep the building temperatures down (however, it seems like those too have failed - presumably they were electric powered).

However, once the cooling capacity in the containment building is reached - the only option is to vent it to the atmosphere.

[ImA20SomethingGetMeOutOfHere]

http://www.housepricecrash.co.uk/forum/index.php?showtopic=160968&view=findpost&p=2924962

Please read.

Edited March 13, 2011 by ImA20SomethingGetMeOutOfHere

[billybong]

Reston, Virginia - It was announced today by an expert, that the mainland of Japan was moving due to the 8.9 magnitude earthquake recorded yesterday.

According to Kenneth Hudnut, a geophysicist from the U.S. Geological Survey (USGS), the bed rocks in the area where Japan is situated was moving that's why it shifted for eight feet or almost equivalent to 2.5 meters.

Even the movement of the earth's axis was affected by the said tremor.

...

[Damik]

You're missing the point: you claimed that it was possible to make a reactor that could withstand any earthquake, which implies that there is an upper limit to the energy released in an earthquake.

I queried that, and you gave a cryptic reply about 9.81m/s, which suggests that you see a reactor falling down a hole as the only way an earthquake can damage said reactor. You need to thing more outside-the-box, as it's easy to come up with lots of other ways in which an earthquake can crush any man-made object

My point is that the reinforced concrete buble 15m big is not very sensitive to statistically common earthquakes. perhaps if you put it on the top of Krakatoa it will crack. Otherwise it will shake left and right or up and down, but it will not crack. Perhaps it can be crashed between tectonic plates, but we are getting more to sci-fi IMO.

Edited March 13, 2011 by Damik

[OnlyMe]

The reactor has pressure relief valves that automatically open at a preset pressure - around 1100 - 1200 psi on this particular type of reactor. Because the steam will be slightly radioactive, the steam is vented into the containment building. The injection pumps will be designed to cope against the maximum design pressure of the reactor.

To prevent the containment building blowing up from steam pressure. The steam doesn't just go into the air - but is released into a series of cold water 'surge' tanks surrounding the reactor within the containment building. These cool the steam and condense it back into water and prevent a pressure surge in the containment. This works fine for a number of hours, until the water in the the surge tanks boils. At that point, temperatures and pressures in the containment start rising dramatically. Under normal circumstances, there would be emergency reactor cooling systems that dump the heat outside the containment preventing the reactor venting into containment - and even if those failed, there would normally be containment cooling systems to keep the building temperatures down (however, it seems like those too have failed - presumably they were electric powered).

However, once the cooling capacity in the containment building is reached - the only option is to vent it to the atmosphere.

All well and good in "normal" operating conditions, if the core is damaged then it is not just steam being released but copious amounts of hydrogen as well as was apparently the case with the containment building that blew its top. What would they prefer to do now - just vent to the atmosphere so that they can carry on working wihtout the risk of another explosion which only makes the situation worse/ If they are sure there is no hydrogen they could carry on as per normal procedures.

[sbn]

9.81m/s has got nothing to do with gravity. Gravity is an acceleration, not a speed. Maybe he meant 9.81m/s/s but I don't see what this has to do with an earthquake?

Duh - that's how fast you accelerate towards the floor if something topples you from upon which you are standing!

How fast and in what direction the floor is accelerating towards or away from you is another matter altogether!

This earthquake sh** is MAD sh**!

[_w_]

What I want to know is WHY aren't we getting anything like this from our media or the Met Office?

Because they NEVER want you to worry your pretty head with important matters that you surely can't understand.

That's the way it is these days.

[Damik]

the containment building can also melt.

this is an interesting calculation someone has made made on whether the containment floor could melt:

asumptions for calculations (not related to the japan incident): We estimate the floor of the containment to be 140 feet in diameter, and ten feet thick. This is a volume of 3,750 cubic meters of concrete. Using the density of quartz (2.65 g/cc -- concrete is made of sand (quartz) and gravel), this is a mass of 10 million kg, or 10,000 tons.

Suppose the reactor to be of average size, 1GW (1 Giga watt, or 1000 Million Watts). Since electric power plants are typically about 33% efficient, tossing 67% into the cooling towers and the water passing through the condensers, a 1GW power plant will need 3GW of heat energy to be released in the core.

The 7% of full energy that is initially produced by the radioactivity of the fission products (page 208) lasts only briefly, but 1% lasts a day, and ½% declines to ¼% only after 11 days. Assume we are down to 1% when the reactor vessel releases the molten mass to the floor.

1% of 3GW is 3x107 or 30,000,000 Joules per second. In one day this produces 2.5x1012 Joules. It would take another 14 days at ½% of 3GW to completely melt the concrete slab. The heat required to transmit a temperature sufficient to produce steam at the critical temperature (370 degrees) in the supporting moist earth would, according to these calculations, occur in 3½ days. To melt a hole in the concrete slab 25 feet across at the top and 12 feet across at the bottom would take 10 hours.

and how would you cool the containment building:

in order to remove heat at the rate required (15,000,000 Joules/sec) on a continuing basis, cold material would have to be introduced into the containment, used to absorb heat, and removed hot. Some kind of circulating system would have to be functioning. This involves working equipment inside the containment in which uranium is melting, and is subject to malfunction.

In theory, the condenser coolant, the water that is used to condense the steam in the normally-operating reactor, could be re-routed to cooling coils built strategically into the concrete floor slab. (If they were inside the containment, they would be in danger of melting.) If water is pumped in at 20 degrees and taken out at 80 degrees, the quantity required would be about 1000 gallons per minute.

As with other schemes, pumping is subject to failure, and maintenance of imbedded cooling coils is problematic. From minor cracks in the concrete due to long-term settling of the foundation to uneven heating over the concrete area resulting from un-evenness in the melted layer, there are many ways for such a cooling system to fail just when it is needed.

I am not sure about your numbers but I assume that the containment designers can calculate them as well and put enough right material under the reactor. Concrete is not very expensive so it does not seem as a problem to me ...

[Damik]

The water being pumped also contains boron which interferes with the nuclear fission reactions. The shutdown rods contain boron which is what keeps the reactor shut down. The concern, if the fuel has melted is that if it pools at the bottom of the reactor (out of reach of the shutdown rods) the reactions could restart, and the amount of heat that needs removal becomes an even bigger problem. The boron should stop the reactions from restarting.

Good post. Damik needs to read this before he makes another post.

Surely the bottom of the containment is designed that the reaction can not restart. Is not it the purpose of the containment building??? As you can be assured that if it melts it will all end at the bottom ....

Edited March 13, 2011 by Damik

[mfp123]

I am not sure about your numbers but I assume that the containment designers can calculate them as well and put enough right material under the reactor. Concrete is not very expensive so it does not seem as a problem to me ...

im not suggesting it will happen, and presumably when they pumped the seawater in they will have cooled things enough sufficiently.

but if the molten core does breach the container due to lack of cooling, there is only molten core vs concrete in the way of a big meltdown.

if they can keep the molten core stablised inside the containment building, this would require some cooling, and as we have seen the failure of the pumps so far, this is an issue that needs to be considered, thats all i was saying.

Edited March 13, 2011 by mfp123

[bogbrush]

Because they NEVER want you to worry your pretty head with important matters that you surely can't understand.

That's the way it is these days.

Ah "THEM". Of course.

[Damik]

im not suggesting it will happen, and presumably when they pumped the seawater in they will have cooled things enough sufficiently.

but if the molten core does breach the container due to lack of cooling, there is only molten core vs concrete in the way of a big meltdown.

if they can keep the molten core stablised inside the container, this would require some cooling, and as we have seen the failure of the pumps so far, this is an issue that needs to be considered, thats all i was saying.

by "container" do you mean the reactor vessel or the containment structure around the reactor vessel ???

I am arguing that total loss of the coolant for a few days/weeks is a scenario this thing is designed to support and do not leak the core to the soil under the reactor.

It is also designed to do not explode, just to release gases or steam.

Edited March 13, 2011 by Damik

[fellow]

by "container" do you mean the reactor vessel or the containment structure around the reactor vessel ???

I am arguing that total loss of the coolant for a few days/weeks is a scenario this thing is designed to support and do not leak the core to the soil under the reactor.

It is also designed to do not explode, just to release gases or steam.

And what if the fissionable material explodes, like it did at Chernobyl?

If they can't get enough cooling to it, then this is a real possibility.

Edited March 13, 2011 by fellow