Japan puts top priority on nuclear plant's No.3 reactor (only one … powered with plutonium)

[OKIsItJustMe]

http://www.reuters.com/article/2011/03/16/us-japan-quake-nuclear-radiation-idUSTRE72F3MB20110316

Japan puts top priority on nuclear plant's No.3 reactor

By Osamu Tsukimori and Mayumi Negishi

TOKYO | Wed Mar 16, 2011 8:20am EDT

TOKYO (Reuters) - Japan put its top priority on Wednesday on efforts to cool down a plutonium-fueled nuclear reactor, attempting at one stage to water-bomb the facility without success amid fears that authorities were running out of options to avert disaster.

The No.3 reactor is the only one of the quake-stricken Fukushima Daiichi plant's six reactor units to be powered with plutonium, which is far more hazardous to health than uranium, which is used to power the other five reactors.

High radiation levels had stopped a military helicopter from dumping water on the No.3 reactor, local media said. The plant's owner, Tokyo Electric Power, declined to comment.

It was not clear if the helicopter was trying to pour water on the reactor vessel or on an associated spent-fuel pool, a deep reservoir where spent nuclear fuel rods are kept. Public broadcaster NHK said the water was for the spent-fuel pool.

…

[Statistical]

1. One would imagine the helicopter was for filling the cooling pond right?

I mean pouring water into cooling pond and covering the exposed and boiling fuel rods would be useful.

Splashing the outside of the reactor containment structure with water would do absolutely nothing to the heat inside the core.

[CRH]

2. Something about reactors 1-3 has confused me since Saturday, ...

All three now have had hydrogen explosions that appeared quit powerful, enough that it blew the tops and some cases the sides of the reactor building into the atmosphere. These explosions supposedly took place outside the reactor containment and presumably below the spent fuel storage ponds, located above the reactor vessels, near the roof.

So how did these explosions spare the ponds and not blow irradiated water and chunks of fuel rods into the atmosphere as well?

[FBaggins]

5. Water is much less susceptible to a gaseous explosion than you might assume.

It isn't very compressible.

Throw a grenade into a pool and you'll see quite a splash. Fill a room (with a pool in it) with natural gas and light it off (don't try this at home kids), and you'll knock the walls down but not do much to the pool apart from fill it with debris.

It's the difference between diving into a pool from a diving board and falling from a plane. It almost might as well be concrete at that point.

I'm not saying that nothing at all could have happened in these cases, but when comparing the surface of the water to the comparatively light outer shell of the upper part of that building, the water should win easily.

[CRH]

6. So the water, and the concrete pool sides, ...

absorb or deflect the power of the blast, leaving the weakest point of escape for the exploding gases, the walls and roof? It will be interesting in the future when this is all studied, to see if the containment ponds were a hundred percent after the blasts, or if perhaps they are now leaking making it more difficult to maintain the fluid levels as well as making the reactor building a more toxic environment.

Thanks for you input, FBaggins. Though I am from the 'no nuclear' side of the debate, I appreciate your attempts at explaining the more technical aspects of nuclear energy, even though often assaulted for your opinions. The two sides need to hear each other, to temper arrogant perceived omniscience.

[AtheistCrusader]

7. They will never use this design again.

In fact, we are likely to see the near-term shutdown of all reactors of this type and generation.

Germany pulled the plug on nearly half their reactors last night for this reason. They left open the possibility of re-activating them after studies are performed, and risk mitigation added around the cooling systems, but frankly, those 7 reactors are probably headed for the dustbin.

[FBaggins]

8. This design hasn't been used for quite some time.

In fact, we are likely to see the near-term shutdown of all reactors of this type and generation.

I doubt it (unless "near term" also means "short term"). The Japanese will probably improve their backup generation capability for those remaining plants along the ocean, but they aren't going to just close down operating units when they have rolling blackouts already.

Similar plants in the rest of the world will be subject to an analysis re: whether the same kind of thing could happen there. Those that aren't near significan't earthquake zones or serious flooding risk won't be closed for long (if at all).

It isn't as if this model failed on a sunny day because someone threw the wrong switch or skipped a step in a test.

[Wilms]

11. A few years back every one of TEPCO's 17 reactors were shut.

Now, did they have rolling blackouts for that?

[FBaggins]

12. You didn't by any chance notice news of an earthquake did you?

A few years back they hadn't also lost other generating facilities.

They have rolling blackouts now. You think turning off additional plants will improve that picture?

[Wilms]

14. Get over the snark and reread what I wrote.n/t

[FBaggins]

15. Ok... I re-read it... you get the same answer.

You're saying that closing 17 plants several years ago didn't cause blackouts. Implying "so why should it now?"

The answer is obvious, and has been given to you. You're talking about shutting down additional plants over and above the level that is already causing blackouts.

[Wilms]

16. No. I'm simply asking how did that work at that time. n/t

[FBaggins]

17. Ah. Presumably it wasn't a problem

Apart from the costs involved (nuclear power is by far the cheapest baseload power once the plant is already built).

They likely had the option to ask other power companies to delay refeuling cycled in their reactors while the inspections were underway... as well as put off maintenance (etc) at other power plants that would have idled them at the time. Power grids are usually designed with a significant surplus capacity to handle some plants being offline unexpectedly. I imagine that 17 reactors would have been a challenge, but not unmanageable.

The current shortfall is much larger.

[Statistical]

9. There are 23 reactors with the same dangerous design in the US.

I am pro nuclear but believe the MK I should be shutdown. Period.

Still I doubt it will happen. A nuclear reactor has very low operating cost, 95%+ of the cost is construction & interest. Costs long since paid, every year they run is billions of dollars in pure profit.

We need to nationalize nuclear reactors in the US. I very rarely use the nationalize word and often attack people who say it but in this instance we need to nationalize them.

[OKIsItJustMe]

10. Re: 95%+ of the cost is construction & interest

Not according to this:
http://www.eia.doe.gov/oiaf/aeo/electricity_generation.html

[FBaggins]

3. One suspects that "top priority" is a relative term.

There's some pretty high priority being places on the other too... one would hope.

Of course... that could be how they ended up with trouble in #s 4-6. They may have shifted too many resources away from them (assuming they were safe).

[ELY08]

4. Good question CRH

I also have been asking this question. One would "guess" that the spent fuel would exist in all 6 of the reactor buildings.

[FBaggins]

13. RE: Plutonium

As I understand it, the biggest concern their right now is the spent fuel pool. The plant only shifted to MOX in the later part of last year, so you wouldn't expect any of the MOX to have made it to the pool yet.