3 Fukushima reactors cooled below 100 degrees

[FBaggins]

The temperature of another troubled reactor at the Fukushima Daiichi nuclear power plant has fallen below 100 degrees Celsius for the first time since the nuclear disaster in March.

Tokyo Electric Power Company or TEPCO says the temperature in the lower area of the Number 2 reactor stood at 99.4 degrees at 5 PM on Wednesday.

Temperatures at the Number 1 and 3 reactors have been maintained below 100 degrees Celsius since August.

The utility says its cooling efforts have achieved results although it is too early to say that it has attained a state of cold shutdown for all 3 troubled reactors.


http://www3.nhk.or.jp/daily/english/28_31.html

[txlibdem]

1. I applaud their continuing efforts

But, IMO, it's still pretty stupid to use 50 year old technology.

Japan, modernize your nuclear power plants with thorium cycle power plants and other Generation IV plants. Your future safety depends on it.

[FBaggins]

2. I'm sure they're trying hard (though they had to redefine "cold shutdown")

But the real story here is that all three reletively quickly moved to <100 degrees once they shifted to using the core spray in the RPV after months of pumping water into the dry well through the feedwater system.

This implies that the bulk of the core remains in the RPV rather than at the base of the primary containment (or obviously, as some pretended, continuing to burn it's way through the earth beneath the reactor).

[madokie]

3. The 100 degrees is Celsius and not Fahrenheit, big difference

Generally when we talk about temperature in normal conversation as this is here we're talking in Fahrenheit unless we state otherwise. You have to read the link to see that they're talking about 100 degrees Celsius.
My point is the nuclear power industry will and do everything they can to mislead as much as humanly possible as this is proof of.

[FBaggins]

4. Did someone say it was Fahrenheit?

1) This is Japan we're talking about. They switched to metric over 50 years ago.

2) This is also reactor physics that we're talking about. That's almost always been metric (though you could have spun the question to why this wasn't Kelvin)

3) The goal was "cold shutdown" which has long included a sub-boiling-point temperature. Pretty much everyone knows that this means we're talking Celsius.

My point is that you seem to do everything you can to twist a conversation... even if you have to make up both sides of the conversation to do it. :)

And no... it isn't really a "big difference" since either would be good news. As I pointed out. The big news isn't the specific temperature, but rather that this alternative cooling strategy has been more effective than what they were using. Leading to a pretty solid (though not conclusive) evidence that the cores did not, in fact, entirely melt through the RPV (let alone the primary containment). The current guess is that the bulk of the corium remains in the RPV, with a significant proportion still above the support plates.

Will that stop the "Where's the corium???" nonsense? Of course not... because they're less influenced by evidence than you sometimes are. :)

[madokie]

5. I said when WE talk about temperature here in polite company we talk in Fahrenheit

or we say Celsius
I don't even know where to start with the rest of your spiel its so far out there.

removed irrelevant part

[FBaggins]

6. You also said that it was proof that the nuclear industry was twisting the story.

It's pretty nutty to imply that a Japanese company had to encourage other japanese companies (multiple papers) to leave off something (reporting in F) that they always leave off since the Japanese don't work in Farenheit.

I suppose the conspiracy really goes back to the 50s when the nuclear industry convinced Japan to switch over... in anticipation of fooling you decades later.

Can you remember ANY reporting from a Japanese source during this entire event that EVER reported a Fukushima temperature in Farenheit? When they reported estimated temperatures or the melting point of zirconium or the current water temperature in a fuel pool (etc etc etc)?

This is just the latest in a long chain of errors demonstrating that you really don't speak the language of physics. We use SI pretty much from the highschool level.

removed irrelevant part

Lol... not all of it. :)

[Nederland]

7. That is a typically American centric view of the world

Yes, when Americans talk about temperature we talk in Fahrenheit, but the OP from a Japanese source, so THEY use Celsius--like most of the world.

To suggest that a Japanese source should use Fahrenheit in its titles just so stupid Americans that don't want to read the first paragraph of the article don't get confused is rather ridiculous. To suggest it "proves" that the nuclear industry is out to mislead everyone is simply ignorant.

[Yo_Mama]

8. Everyone uses metric except us

We're like that coelacanth fish they thought was extinct and then found. We're a living fossil. Tourists come over here and can't get over our delightfully medieval measurement system. They feel like they went to Jamestown and participated in A Day Of Living History.

Metric, my dear, IS THE STANDARD.

[Nihil]

11. Obvious to most people though ...

... seeing as how 100C is a very well known boundary temperature
and 100F isn't ...

:shrug:

> My point is the nuclear power industry will and do everything they can
> to mislead as much as humanly possible as this is proof of.

Whilst there is a lot of truth in the first part of your comment,
this is most definitely not "proof of" it.

Face it: If the headline had said "... cooled below 212 degrees", not only
would that have caused a brief panic across the rest of the non-US world
(if they hadn't had their morning coffee) but I bet many of your compatriots
would have "assumed" that they meant Celsius in order to perceive another
worst case option ...

:evilgrin:

(Edit for typo ... didn't want people to think that a "boundary temperatute"
was meaningful jargon for anything!)

[FBaggins]

12. Hey! Let's not take it too far. 100F is also a well-known boundary temp.

Down here we call it "stinkin' hot!"

:)

[Yo_Mama]

9. I did see an argument that they should test the temp below the reactor vessel

before claiming cold shutdown.

They also hugely increased the amount of water they were pumping in. The key to that was getting their water purification/recycle thing going. It has been less than perfect, but it allowed them to cool the vessels without dumping tons of water into the ocean.

[Yo_Mama]

10. They were injecting water into the reactor vessels, not the drywell

They did flood the drywells, but they were injecting water directly into the RVs. So I think your theory does not hold up.

The change has been mostly in the flow rate, and of course time.

Until they really got the purification/recycling of the basement water working decently, they couldn't increase injection rates. They deliberately slowed the pace of water going into the RVs as much as they could without letting the temps rise much because they were so worried about overflow.

They put water in those vessels and it just ran back out and ended up in the basements, so until they could develop a way to pull the water back out of the basements they couldn't put in as much as needed.

[FBaggins]

13. You're right of course. It was the bottom of the RPV

But they speculated that it still wasn't cooling the fuel efficiently while the core spray has been more effective.

Of course whatever they pump in was just leaking out the bottom of the RPV, so any fuel remaining above the support plates was cooled only by whatever steam rose past it. But if all/most of the corium was sitting at the bottom of the drywell (or worse, in a hole beneath it), then there wouldn't be a change in efficiency between the two sources... just a change due to total volume. But they've varied the volume over the months and seen how effective it was, and cut back on some of the feedwater input as they've ramped up the core spray (though yes, the total is higher).

[Yo_Mama]

14. RIGHT

The core spray took a lot of volume and of course they had to get the things cooled enough to be able to work around the reactors and rig the systems. But it has worked. And that makes the case that a lot of the fuel remains in the reactor vessel, IMO. We won't know for maybe a decade or two - it will take a long, long time before they can get in there and see what happened in each reactor and really examine the substructures.

Still, based on air and seawater testing, emissions from the reactors are very low now.

I never, ever thought I would see a nuclear accident like this in my lifetime. I understand how it happened, but sometimes it still seems like a novel. However six months after the accident, I was left with the impression that multiple layers of containment are the key to controlling even a horrific accident like this. I don't think they will finish containment and isolation in my lifetime, but they have gotten to the point at which the fall-out is the real problem, regardless of all the "spewing radiation" claims.

Russia still has RBMKs running, and despite the post-Chernobyl mods, that really scares me.

[FBaggins]

15. You're right there too. There's no way to make an RBMK safe.

Yes, the Fukushima reactors were also an old design. And yes, the results would have been better had it been a newer one.

But those MkIs definitely proved their comparative value over the similar-age design of the RBMK. By my guess, the event would have been 50-100 times as bad (in part because they refuel while in operation, so probably five of the six would have been active at the time of the earthquake).

[SpoonFed]

16. I believe TEPCO data...

since it certainly has been quite a long time since the start of this debacle and there is no reason to believe there has been any more misinformation and misdirection coming out from them for a really long time.

Let's just let bygones be bygones.

[FBaggins]

17. As soon as you find a source you trust... Get them to install a new thermocouple.

We'll all start using that data.

Until that happens, this is the only source for temperatures in the reactor that we have. You could, I suppose, continue to rely on your imagination instead... But that hasn't been too reliable, now has it?

[CJvR]

18. Clearly evidence...

...that the corium have left the building and is now tunneling to a location near you!

Repent sinners! :nuke: