Earthquake/Tsunami in Japan

[Mariner]

An interesting perspective available though the following link:

http://energyfromthorium.com/2011/03/15/fd-thoughts/#comments

In the comments, 'Riccio' apparently has plenty of experience of the Fukushima reactors which dates back to the time at which they were under construction. The company he worked for at the time was bidding to install a different design for the second reactor.

Worth a read.

 

[fellix]

A is for Atom - nuclear power, business and politics.

 

[Mintmaster]

Since normal operation invloves sinking 1.5 to 2.2GW heat, 30MW should be no problem at all. The problem is clearly not pump capacity, but that the pumps aren't working at all.

You clearly didn't get the point of my post. It's very simple and cheap to store or even fly in 100 working common engine powered water pumps. The problem must be access to the lines that need pumping. EDIT: or, reading Mariner's link, cracked pipes making pumping futile.

Ever seen a 200MW pot? (residual heat production right after shutdown of a 1GWe reactor)

It doesn't stay at 200MW long enough to cause a meltdown. And yes, we have seen 100MW boiling pots: just look at hot springs.

Besides, what's so special about a 100MW pot? How could it possibly fail at removing heat from a source at the bottom? You think a giant steam bubble will somehow get stuck, levitate all the water above it, and prevent circulation?

 

[fellix]

Ultimate Loyalty: Japanese Dog Refuses to Leave Injured Friend Behind

 

[Kaotik]

Plant 2 at least should be now back in the grid, or at least being put back to grid, which should enable it to cool itself.

 

[zed]

In addition to what I posted about a not just using magnitude to guage a quakes damage (but also distance/land sort etc) heres some more info.
Even though a 9.0 quake has ~10000x more energy than a 6.3 one, in this case the 6.3 one actually shook more

Fry said ground acceleration more than twice that of gravity in some parts of Christchurch was the strongest recorded in a New Zealand quake and up to four times greater than the maximum acceleration measured in last week's magnitude-9.0 quake 130 kilometres off northeast Japan

http://www.stuff.co.nz/national/chr...hurch-earthquake-data-tracks-ill-fated-moment

 

[Gubbi]

You clearly didn't get the point of my post. It's very simple and cheap to store or even fly in 100 working common engine powered water pumps. The problem must be access to the lines that need pumping. EDIT: or, reading Mariner's link, cracked pipes making pumping futile.

That was the point of your post ? You grabbed two posts of mine on two different topics and asked if I couldn't see the disconnect.

You then went on about how easy a small gas powered pump could provide enough water.

Besides, what's so special about a 100MW pot? How could it possibly fail at removing heat from a source at the bottom? You think a giant steam bubble will somehow get stuck, levitate all the water above it, and prevent circulation?

I'm perfectly willing to accept that convection could provide enough flow of water to cool the core. But convection requires a temperature gradient to work, which means you need to cool the primary coolant as it exits the top of the stack.

And you do need cooling! After 24 hours residual heat would still be 30MW, enough to heat 320 tons of water from 20 to 100C in one hour.

Cheers

 

[Mendel]

Now that you brought that up, I wonder why all those idiots calling the disaster in japan "god´s revenge" or something like that are suspiciously silent about why god would also have tremors in place called Christchurch.

I vaguely remember a story about earthquake destroying some kind of big cathedral in the 1600s and how apparently some people lost their faith because of that because only the people that went to church were "killed" and those that didnt go there were "saved". I don´t want to turn this to a religious discussion however, just thinking out loud.

 

[digitalwanderer]

http://godhatesjapan.com/

 

[Mendel]

They've got Tokyo Police departments water cannon trucks coming in or in already to cooldown the building 4's pool (which was tried to cooldown with choppers)

That´s a PR effort. They are desperately trying to show that "hey we are doing something, doesn't this look convincing". They (NHK) are looping the video of choppers dumping water all over the yard and calling it success even though it quite clearly wasn´t. At least once a totally wrong reactor was sprayed by a chopper (the roof of reactor 4) and the rest of the chopper runs seemed to disperse water mostly to the yard. Maybe one of the runs seemed to somewhat hit the reactor 3 but I wouldn´t bet that a whole lot of that would have ended up in the actual pool.

I am not convinced at all that non trivial amounts of water actually reached the spent fuel containment pools in either operation. Even if there was some effectiveness, they should really be doing this constantly and not just one hour a day.

What may help is the restoring of power on the site, but even then they need to install some kind of makeshift pipes to replace the damaged ones... but how would they do that when working in there is so dangerous?

 

[hoho]

Making huge tracts of land unfit for use and making working on site a one way trip to cancer (someone will have to cover everything in sand and cement if things go really wrong) is a big enough catastrophe in and of itself.

Its not nearly as bad as currently the majority of radiation that gets spread around is not uranium/plutonium itself but elements that have far shorter half life and thus the areas would become habitable relatively fast.

 

[Mintmaster]

The BWR reactor vessel operates at pressures over 7MPa so the water boils at around 280 °C. The water is hot, at high pressure and radioactive. The pumps there are not ordinary shop pumps that u just replace.
They need electricity to start those pumps.

Uhh, why would they be pumping 280°C radioactive high pressure water into the reactor? They're not trying to operate the plant and worrying about recycling water through the turbines, genius. They're just trying to cool down the decay heat.

That was the point of your post ? You grabbed two posts of mine on two different topics and asked if I couldn't see the disconnect.

You went through all the trouble of figuring out how much water needs to evaporate to cool 30MW, then you just made silly conclusions.

First, the number you got is trivial to pump in, whether with plant pumps or anything else. Second, you talk about convective circulation and needing active cooling when you were just talking about steam. That's the disconnect. Steam floats rapidly - far faster than 99°C water convects up in a cooler pool - and it evaporates into the air. You're not going to get 2000°C superheated water sitting in a pool to let the core melt. And now...

But convection requires a temperature gradient to work, which means you need to cool the primary coolant as it exits the top of the stack.

Temperature gradient? For what? Steam has 1/1700th the density of water.

Yes, 30MW can easily bring to the water to 100°C, then it boils, floats up, enters the atmosphere, and you can dump water back in the top to replace what left. What's so hard to understand?

 

[Mendel]

What are your thoughts about if the used fuel rods can not be cooled and the water runs out, is a Kyshtym type explosion possible?

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

In September 1957 the cooling system in one of the tanks containing about 70–80 tons of radioactive waste failed, and the temperature in it started to rise, resulting in a non-nuclear explosion[citation needed] of the dried waste having a force estimated at about 70–100 tons of TNT, which threw the concrete lid, weighing 160 tons, into the air.[2] There were no immediate casualties as a result of the explosion, which released an estimated 2 to 50 MCi (74 to 1850 PBq ) of radioactivity.[1][3][4]

In the next 10 to 11 hours the radioactive cloud moved towards the northeast, reaching 300–350 kilometers from the accident. The fallout of the cloud resulted in a long-term contamination of an area of more than 800 square kilometers, primarily with caesium-137 and strontium-90.[1] This area is usually referred to as the East-Ural Radioactive Trace (EURT)

 

[Gubbi]

You went through all the trouble of figuring out how much water needs to evaporate to cool 30MW, then you just made silly conclusions.

No, I didn't.

Chalnoth said you just need enough water to replace the primary coolant as it boils off to cool the reactor in a case where pumps stop working.

I then calculated how much water would be lost. I didn't draw any conclusions at all.

Thanks for participating.

Cheers

 

[MfA]

Mendel ... it says explosion, but I think it more likely it was some sudden pressure break. No pressure can build in the pools apart from in the concrete, which would be unlikely to cause a big explosion.

Still, a fire is perfectly capable of putting contamination high in the air.

 

[Gubbi]

Its not nearly as bad as currently the majority of radiation that gets spread around is not uranium/plutonium itself but elements that have far shorter half life and thus the areas would become habitable relatively fast.

Radioactive iodine has a half life of 8 days, this will quickly be gone.

Radioactive cesium has a half life of 30 years. It is easily absorbed into the body (chemically similar to potassium) where it has a biological half-life of a couple of months.

Strontium-90 has a half-life of 29 years, is chemically similar to calcium and is deposited in bone. biological half-life is thus on the order of a human life.

Cheers

 

[GZ007]

First, the number you got is trivial to pump in, whether with plant pumps or anything else. Second, you talk about convective circulation and needing active cooling when you were just talking about steam. That's the disconnect. Steam floats rapidly - far faster than 99°C water convects up in a cooler pool - and it evaporates into the air. You're not going to get 2000°C superheated water sitting in a pool to let the core melt. And now...
Temperature gradient? For what? Steam has 1/1700th the density of water.

The convective circulation only works to a given water level. It uses a chimney efect to do this. The water that flows trough the nuclear fuel and heats it up is closed from all sides and the heated water and steam flows upward in it like in a chimney. The end of that chimney is under the water level and that creates the convective circulation. The colder water goes down on the sides and then enters from under the fuel cells which are closed, where inside it heats up and rises.
When the water is under a given level that flow stops, and the water closed inside the fuel cells begins to heat up much faster until it evaporates and the fuel cells will be exposed just to the steam. (which has exremly low heat and radiation absorbing compared to the water)

Thats also how the newer reactors can cool down the core for 72 hours just pasive. They have better convective circulation inside and use water tanks over the reactor to pump water by just gravitation.

 

[Brodda Thep]

Here is a study done on the pools losing all water.

http://www.osti.gov/bridge/product.biblio.jsp?osti_id=6272964

Even with just air cooling there shoudln't be a meltdown unless the rods were moved in the quake or explosion and a critical configuration was created. But I think it would be terribly obvious if that happened.

On the other hand, the zirconium could start to completely oxidize which will release a lot of radiation products. But then, it says spraying the pool with 100 gallons of water per minute with 70% spray efficiency should keep the temp under 500C. Of course that is about a half metric ton of water per minute. And firetrucks usually are right around 10 metric tons of water. (correct me if I am wrong.)

They are probably just going to keep spewing out radiation until they get their water pressure back.

 

[MfA]

That was not the last NRC had to say about it ... they came up with some extra ways for it to melt down during a fire :

http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr0933/sec3/082r3.html

Also MOX is hotter.

 

[Mendel]

Thanks Brodda Thep. Exactly the kind of information I was looking for. However, I can´t find a reference to mox or plutonium on that document so I think the calculations may not be sufficient for the fuel used in unit 3 of Fukushima.

Now... a business perspective on the effects of radiation even to those that are not in health danger.
Al Jazeera reports:

4:44am

Japan's public broadcaster, NHK, says that a cargo plane arriving in Dalien, China, from the Japanese town of Narita on March 16th was not allowed to unload its cargo of electrical components - after an inspection by Chinese customs officials found radiation levels in the hold to exceed standards. The plane returned to Narita.

So also the radiation part of the disaster is already affecting export business