Japanese reactors may need seawater pumping for years

[LiberalEsto]

The Los Angeles Times has a good update article about what is happening to the damaged reactors in Japan.

Here's one interesting part of it. In a best case scenario:

"Most likely, the company would keep pumping seawater through it for several years until it had cooled down sufficiently and many of the radioactive isotopes had decayed enough that engineers could go in and remove the fuel. That, in essence, is what happened in 1979 in the partial core meltdown at the Three Mile Island Generating Station in Pennsylvania. Workmen eventually dug out the partially melted fuel and buried it at a disposal site in Idaho. The empty containment vessel now stands next to functioning reactors at the site."

Years? I had no idea it could take that long to cool down.

Worst case:

"A breach in the containment vessel. If they happens, engineers would most likely have to entomb the reactor in concrete, as was done at Chernobyl, where a breach spread radioactive ash across most of Europe, except the Iberian peninsula."


http://www.latimes.com/news/nationworld/world/la-sci-japan-quake-reactor-qa-20110314,0,3403230.story

[jody]

1. Pumping with seawater sounds cool but then I thought, where oh where do they pump waste water? nt

[jpak]

5. When the volume becomes unmanageable, it goes into the sea

n/t

[AtheistCrusader]

2. That seems like a bad idea long-term.

Given the unknown nature of any physical damage to the core containment, and it being steel... seawater is corrosive..

[customerserviceguy]

7. Clearly, it means that these reactors are dead

and will not easily be refurbished any time soon. It's the last of a desperate set of dwindled options.

[AtheistCrusader]

9. I know. But how will the steel containment hold up to 10 years of seawater?

Not only does it have to contain the fuel for now, but, if that is accurate, for a very long time into the future during cleanup.

[customerserviceguy]

12. They're probably going to have to entomb the entire thing

in quite a few feet of concrete, making the site unusable for milennia.

[AtheistCrusader]

13. Maybe. Let's wait and see. They didn't have to do that at TMI.

[Fledermaus]

3. Its only recently that the snow quit melting on the Chernobyl Sarcophagus

Twenty years later.

[meow mix]

4. "No immediate danger at Japanese nuclear plants" they said

nuke lobby can kiss my ass

[Tesha]

6. Radioactive decay goes on for quite a long time.

Technically speaking, radioactive decay goes on
forever, running down "exponentially"; that means
that there's a lot of heat initially produced (say,
6% of the reactor's full-power output!) but after
a few years the heat is down to manageable levels.

To accommodate that, spent fuel rods spend their
initial years racked in pools of cooling water
inside the reactor's containment building or other
secured structure. Nowadays in America, because
we have no actual way to deal with spent fuel,
they then move to "Dry Casks" which are usually
stored outside. At that point, the fuel rods are
still hot but no longer in need of active liquid
cooling.

Someday we may Americans even figure out what to
do with them next!

In other parts of the world, they take the rods,
chemically separate out the unburned uranium, the
"bred" plutonium (formed from unburnable U238 +
neutrons),and all the other crap, put the uranium
and/or plutonium back into new fuel rods, and hope
and pray that a miracle makes the rest of the crap
disappear.

So far, it hasn't disappeared.

Tesha

[poverlay]

8. I'm just a layman, and more of a history buff than a nuclear expert, but why can't they just use a

Whole bunch of graphite bricks to absorb the radiation and shut down the reaction like Fermi did in Chicago?

[AtheistCrusader]

10. It's already shut down.

Fission is more or less done, the core is sub-critical.

Now it's just decay heat, which is high enough for things to melt and burn.

[poverlay]

11. Ahhh, thank you. I need to do some research. I hate not having a full understanding of something!

N/t