IAEA says disaster risk decreasing at Fukushima

[FBaggins]

Vienna - The risk of a worst-case nuclear disaster at Japan's Fukushima power plant is decreasing every day, a senior official of the International Atomic Energy Agency (IAEA) said Saturday in Vienna. 'I think as the days go by, and as we see now electricity being connected to those (reactor) units, the efforts with the water, that that risk is reducing day by day,' senior technical officer Graham Andrew reporters.

He specifically mentioned the ongoing injection of seawater into the tsunami-stricken reactors to keep them from overheating. 'So things are going in the right direction,' Andrew said. However, Andrew allowed that there still was a risk that the situation escalates. 'Could we have something unexpected? Most certainly,' he said.

http://www.monstersandcritics.com/news/asiapacific/news/article_1627322.php/IAEA-says-disaster-risk-decreasing-at-Fukushima

[Make7]

1. Let's hope this is right and things continue to improve. ( n/t )

[Name removed]

2. Deleted message

Message removed by moderator. Click here to review the message board rules.

[FBaggins]

3. A half-filled pool isn't a "decreased" risk vs. an empty one?

We don't have any idea how far the water levels fell or how much they've increased. You're not in a position to say "no" any more than I am to say "yes".

They didn't say "there is no remaining danger". They said that the risks were declining.

I'm really sorry if anything short of Chernobyl depresses you. You'll just have to learn to live with disappointment. :)

[ReturnoftheDjedi]

4. We were told the pools at 3 & 4 were empty. There has been no claim that they are now half-filled.

You just made that up.

And in fact, a pool with a small amount of water could be more dangerous than an empty pool.
Rods will still melt and with low water levels, and with water present criticality could be achieved.

Just because they have power back at 5 & 6 means little since those two were never really a problem.

But it gives them a good press release amidst all the bad ones.

[FBaggins]

5. You were "told" that by people who didn't know.

You have since been told that they weren't (after visual inspection). The radiation levels (and lack of tons of smoke) bear this out.

And in fact from what I've read, a pool with a small amount of water is more dangerous than an empty pool.

What you've read is wrong.

Rods will still melt and with low water levels, and with water present criticality could be achieved.

A ridiculously small chance of that. You're thinking of the water slowing down neutrons so that fission could begin? First you have to get unlocky enough for a critical mass to form in a workable configuration and then you have to get a neutron to start things off... where's it going to come from?

Regardless... the FAR FAR more dangerous/likely scenario would involve an uncontrolled fire in that pool... and SOME level of water obviously helps that.

Just because they have power back at 5 & 6 means little since those two were never really a problem

It certainly helps. Those pools were heating up too... just slower since there wasn't any damage.

But power lines have also reached #1 and #2... they just haven't turned it on yet.

[ReturnoftheDjedi]

6. actually the only photo evidence showed the pool in 4 was dry.

nobody's been up there to visually inspect it any other way.

no steam, no water.

that was before they started the desperate hosing efforts, but do you really think that has been successful in refilling an empty pool?
They can't get enough water in fast enough to keep it from vaporizing away.
Even they have admitted that those efforts had little success.

You are really invested in explaining all this away.
Ask yourself, why is that?
Why is your first inclination to say that everything is ok?

[FBaggins]

8. No it didn't.

You can't even SEE the pool itself in that photo... let alone the bottom of the pool.

nobodies been up there to visually inspect it any other way.

"Visually" was by helicopter.

no steam, no water.

No smoke, no fire. Those fuel assemblies aren't going to sit in there uncooled for long without a fire.

But they have been getting steam out... so you can apply that to your own formula. :)

that was before they started the desperate hosing efforts, but do you really think that has been successful in refilling an empty pool?
They can't get enough water in fast enough to keep it from vaporizing away.

Don't be silly. It doesn't go througn THAT much heat. They did almost 1300 tons of water in the last shift. You're thinking of the earlier efforts that hardly seemed to get much into the hole. They now have a "super pumper" truck feeding a special fire truck with a 70-ft-high boom. They're getting LOTS of water in there.

[ReturnoftheDjedi]

9. they weren't pumping that water through a hose directly to the pool

They got steam out because they sprayed water in. It wasn't there when the pool was empty.
If it's turning to steam as soon as it gets there, then they are not refilling the pool, are they?

They have been spraying water in the general direction of the pool and hoping some of it got in.
even with the extended boom, this is still the case.
They are hoping that water is getting into the pool.

This was never supposed to be the way to get water to the pool.

It's ludicrous for you to act like this desperation move is actually getting the job done.
But I can understand why you feel the need to.

[FBaggins]

10. They have, in fact, been pumping water through a hose irectly into the pool

They got steam out because they sprayed water in. It wasn't there when the pool was empty.
If it's turning to steam as soon as it gets there, then they are not refilling the pool, are they?


That's incorrect. As I posted yesterday, it means (or at least hints) that the water level (whatever it is) is not covering the entire rods. It doesn't mean that the pool is dry.

They have been spraying water in the general direction of the pool and hoping some of it got in.

That's what was happening earlier... they seem to be having a great deal more success with the current equipment.

even with the extended boom, this is still the case.They are hoping that water is getting into the pool.

"Hidehiko Nishiyama, deputy director-general of the Nuclear and Industry Safety Agency, told reporters that a review of video shot from a helicopter and an on-the-ground check by a worker had confirmed that there is water in the pool."

There wasn't ever anyone in the know who said that the pool was dry. It should have taken days for it to dry up, so the speaker would be making assumptions and guesses about how much damage was done. Shortly after Jaczko said that, the Japanese apologied for not getting him information in a timely manner, but that there was water in the pool.

This was never supposed to be the way to get water to the pool.

Duh... ya think?

Doesn't mean that it isn't working. This isn't rocket science. It's a pool and a hose. The stakes are high, and the environment is challenging, but the process is not complicated.

[ReturnoftheDjedi]

11. you're wrong. the hose doesn't go into the pool. it's just pointed in that direction.

and the latest I just heard on CNN is that they believe there is a hole in the #4 pool.
How does that affect your position?

If there was just a little water in the pool, then there would be steam.
When Jaczko said it was empty, there was no steam emerging.
Then they started spraying it and saw steam again.

No steam = No water

The rods are most definitely exposed to the air, and they are unable to refill the pool.
What do you think will happen if that condition remains?

[FBaggins]

12. It doesn't "affect" my position. It IS my position.

the latest I just heard on CNN is that they believe there is a hole in the #4 pool.
How does that affect your position?

As I said yesterday. My "take" on the situation is that the explosion in #3 must have damaged the side of the pool in #4... causing it to lose the water down to a certain level that is both high enough to avoid a fire and low enough that parts of the rods are exposed (that's a big range since they're so long). It can't be entirely dry or there would have been MUCH more radiation (and it wouldn't have been as transient) and it can't be TOO high either or you wouldn't get much steam when you sprayed water in there.

If there was just a little water in the pool, then there would be steam. When Jaczko said it was empty, there was no steam emerging. Then they started spraying it and saw steam again. No steam = No water


Not quite true. The water has to be boiling substantially in order for there to be constant steam. If (as I speculated above) the pool is partially filled and THAT level is refreshed by ongoing spray (plus leakage above a certain level), those results would be reasonable.

Also... that "spray and then wait for steam to end" was from over a day ago. All I've seen lately was claims of a seven-hour shift of continuous spraying. With results that they seem quite happy with.

The rods are most definitely exposed to the air, and they are unable to refill the pool.
What do you think will happen if that condition remains?

If they're able to keep water on target for extended periods of time... not much at all. Except that I wouldn't want to place myself anywhere above the lip of that pool. :)

[ReturnoftheDjedi]

14. there was an explosion at #4, too

[FBaggins]

15. Absolutely.

Doesn't really change the overall read though. There's presumably damage part-way down the wall of the pool (since it wouldn't have boiled dry that fast even without cooling)... but not all the way down or the results would have been much worse than what we've seen.

[ReturnoftheDjedi]

17. "but not all the way down or the results would have been much worse than what we've seen."

this is an assumption and is far from certain.

time will tell.

[Turbineguy]

7. We are finding out more and more

as time goes on. As it turns out, a lot of people far away from the scene were telling the world what was happening based on their conjectures. People getting their names and faces on TV in order to sell their books or crackpot theories.

As for the info about the #4 spent fuel pool being empty, you can easily see the water level in the published photo and it is above the fuel. And that was 2 days ago.

[FBaggins]

13. Your post highlights an interesting phenomenon.

Others look at that same photo and see it as proof that the pool was entirely dry. You say that you can easily see the water level.

I can't see a blasted thing. :)

[Turbineguy]

16. If the #4 pool were low

you would be able to see the fuel rods. A substantial portion of the pool can be seen. If the pool were without fuel I would agree that the it would be difficult to determine the water level. The steam seen in the photo is clearly above what I perceive as the water level. In order for steam to be generated, the water does not need to be boiling, it only needs to be substantially higher in temperature than the surrounding air (much like seeing a cloud of vapor from your breath on a cold day).

In addition, TEPCO has confirmed that there is water in #4.

Some may say that they do not believe any of this and that's fine. When it comes to engineering I do not get into religious arguments. The people at the scene know the most. They have to. Also, being surrounded by 1000 psi steam and machinery that can squash you like a bug tends to promote honesty.

On edit: In your posts on other threads you bring up the aspect of radiation even if the rods are covered. Good point. I was more concerned about spontaneous criticality of the fuel than elevated radiation.