TEPCO says reactor #1 is 715-735 Fahrenheit

[bananas]

From GD:

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=439x719480

Fukushima reactor core No. 1 is now running 30% hotter than normal temperatures.

Just to give an update on some bad information that was posted here on DU last week which claimed the reactor temperatures had been brought down to only 1% of their average temperatures, Reuters reports today that reactor no. 1 has reached 380-390 Celsius. It's designed to run at 302 Celsius.

http://www.reuters.com/article/2011/03/22/us-japan-quake-idUSTRE72A0SS20110322

I thought they had stabilized the cores, now I am not certain.

The Reuters article:

http://www.reuters.com/article/2011/03/22/us-japan-quake-idUSTRE72A0SS20110322

IAEA tracks radiation leaks at Japan's crippled plant
By Risa Maeda and Kazunori Takada
TOKYO | Tue Mar 22, 2011 7:55pm EDT

TOKYO (Reuters) - Japan's earthquake-hit nuclear complex is still emitting radiation but the source is unclear, a senior U.N. atomic agency official said, as workers faced another day of struggle on Wednesday to cool damaged reactor cores.

<snip>

Concern has also grown over the core of reactor No. 1 after its temperature rose to 380-390 Celsius (715-735 Fahrenheit), TEPCO executive vice president Sakae Muto said. The reactor was built to run at a temperature of 302 C (575 F).

<snip>

[FBaggins]

1. Liars!

I have it on good authority that they're in the multiple thousands of degreed.

Why... I read it right here for an irrefutable authority.

Just to give an update on some bad information that was posted here on DU last week which claimed the reactor temperatures had been brought down to only 1% of their average temperatures

I don't think that's true. It's that the reactor is producing (roughly) 1% of the power/heat that it would produce in operation.

That's still enough to heat things up if you can't recirculate the water and don't want to release steam.

The good news that's missed here is that they have temperature sensors back up and running in three (?) of the units. Their decisions on when/if to release steam or add water were based to some degree on guesswork without them.

[bananas]

2. No, it's under 100 degrees, I read it right here. nt

[FBaggins]

3. Nope.

They said that the outside of the buildings were below 100 (prior to the fires). This is inside the core.

An entirely different thing.

[girl gone mad]

15. Well, people here were claiming the reactors were running at only 1% thermal output..

so that would be 3 degrees Celsius.

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=439x654832

[FBaggins]

18. You've confused "thermal output" and "temperature".

Some would say "power" as well... which just further confuses things.

The heat generated by the core (on a calories basis) is down to 1% (give or take) of it's full running capacity... but that doesn't mean it isn't hot and getting hotter. It just means that it takes much longer to do so.

The generated heat has to go somewhere. If you can't pump water out and replace it with cooler water then your only option is to release steam (and replace that with cooler water). They don't WANT to release steam... so of course the temperature is going to build up.

I think that until now, they were largely guessing at when to do that... now they have data.

[girl gone mad]

20. I don't think I'm the one that's confused.

By thermal output, I mean the heat coming off of the reactor. Obviously this isn't "useful thermal output". It would be pointless to talk about how much power is being generated.

I would add again that you don't know what is happening inside the core. People keep throwing out that 1%, but I don't know where that's coming from.

[FBaggins]

21. Once again... "heat" and "temperature" are not the same thing.

I wasn't making a comment of how "useful" it was. I was correcting the misperception that if the temperature is above a given level, that must mean that statements about how much the activity in the core had declined were incorrect.

They weren't.

I would add again that you don't know what is happening inside the core. People keep throwing out that 1%, but I don't know where that's coming from.

Pardon what must seem like a sharp reply... but the fact that you don't know where something is "coming from" does not mean that others don't know what they're talking about. A high percentage of the heat generated by an operating reactor is obviously from the fission going on. When that ends, you're left with the heat of nuclear decay. BUT that isn't a constant because there's a mix of fission products in the fuel that are far more active (but have short half-lives). Over the course of several days, those fission products largely die out. The core produces less and less heat over time.

That's why those first couple days were so critical.

[girl gone mad]

24. You should read through the thread I linked to.

It seems like you are making the same erroneous claims that Statistical was making with regards to fission and the posting of a graph on thermal output that has no real bearing on the reactors in Fukushima. It's one thing to cut and paste information from Wikipedia and various web sites, it's another thing to actually understand the concepts that you're talking about.

Until you can show me the data which proves that the ongoing fission in the reactors is at 1% of the average nuclear activity (temperature or heat, in this case they are directly proportional), I will assume that you are as uninformed as anyone else.

[FBaggins]

25. Sigh.

Until you can show me the data which proves that the ongoing fission in the reactors is at 1% of the average nuclear activity (temperature),

1) There is no fission going in in the reactors.
2) "Nuclear activity" cannot be measured by temperature.

On what basis would you claim that whatever graph you saw had "no real bearing on the reactors in Fukushima"? Are they magical reactors that don't follow the laws of physics?

You can look this stuff up yourself. Start with "nuclear decay" to learn where the heat is coming from (so you'll stop making the mistake of thinking it's fission that's going on). Note that these decay events are exothermic in nature (IOW, every time one happens, you get a little heat). They look up "fission products" and take a look at some of the elements that are necessarily in nuclear fuel after a reactor has been running for months and months. Then look up "half life" and find out the half lives of some of those products. The ones that are creating the most heat right after the reactor is turned off... are largely gone at this point.

[girl gone mad]

28. U-235 constantly spontaneously fissions.

Neutrons are still being emitted inside of those reactors as the uranium atoms break apart. Some of the decay products of uranium also emit neutrons. Fission is still ongoing and will be for weeks, at least. The rate of fission and the temperature are correlated.

Where does the arrogance come from?

[ReturnoftheDjedi]

30. he thinks he's a Nuclear Expert. I'm surprised we haven't seen him on CNN.

He could tell the whole nation that All is Well.

[girl gone mad]

35. He's said about ten things now...

which lead me to believe his education on this topic consists of having read a couple of talking points memos.

[FBaggins]

38. I majored in the subject GGM.

You're really just embarrassing yourself at this point.

When you wake up tomorrow I want you to start a new habit. Repeat ten times slowly "bluster does not add credibility".

I promise your day will improve. :)

[girl gone mad]

46. I seriously doubt that.

You need a refund, if so.

[FBaggins]

49. That's ok.

I assure you that the threshold between someone whose opinion on my Physics knowledge is relevant to me... and just entertaining...

... is well above someone who can't tell the difference between temperature and heat.

Better luck next time GGM. It's been fun. :)

[girl gone mad]

51. That's just it.

The fact that you think the difference between temperature and heat is relevant to this discussion is another indication to me that you don't know what you're talking about.

[FBaggins]

52. Did you read your original post in this chain?

When did it suddenly become irrelevant?

I mean... I know you wish it weren't there... but that doesn't make it irrelevant.

You thought that a high temperature disputed the claim that the reactor was putting out only 1% of it's normal heat.

I mean... that's a highschool error.

[girl gone mad]

59. It's not like you're getting heat transfer from some other energy source.

The source of the rise in temperature is the heat of the nuclear reactions - fission and the decay chain.

In the context of the original thread that I linked to, the person was claiming that only a small amount of water was needed to cool the reactors because the thermal output was only 1%. My point was and remains that he had no real basis for those claims.

[FBaggins]

60. There's another one for you.

Nuclear decay is NOT a "nuclear reaction". Decay happens all on its own.

And it represents >99.9999999% of the heat coming from those cores.

In the context of the original thread that I linked to, the person was claiming that only a small amount of water was needed to cool the reactors because the thermal output was only 1%.

And that statement is correct. Far less water is needed to cool a core that's putting out less heat. That's why there have been fewer and fewer stories of releasing steam from one of these reactors.

[girl gone mad]

62. Decay causes reactions..

and you still haven't shown me that the output is 1%.

[FBaggins]

64. One time out of 15 billion in the uranium we were discussing.

The other 15 billion (-1) times the heat comes from the decay.

and you still haven't shown me that the output is 1%.


Actually... I have. You just don't get it.

Check those half lives again.

Time for bed. Thanks for the free entertainment.

[girl gone mad]

68. You still don't seem to understand.

The only thing you're basing the conclusion of 1% thermal output on is a graph of decay heat in a reactor with functional cooling.

What you've actually got at Fukushima is several reactors with no cooling, sea water in the vessels, partial meltdowns, rising pressures (for at least a couple of days), rising temperatures and an uncertain state of configuration.

Admit it, you might as well pull a number out of your ass.

[FBaggins]

69. Nope.

The only thing you're basing the conclusion of 1% thermal output on is a graph of decay heat in a reactor with functional cooling.


You seem to assume that because you're picking up your knowledge by mad googling after the fact... that this must be how everyone does it.

No. I didn't need a graph of decay heat. That's simply how reactors work.

Here's a good primer for you while I'm gone. Let me know if you need any help with the big words.

Note what it says about SF and delayed-neutron fission (the part you missed in the earlier link).

http://decay-heat.tripod.com/

[girl gone mad]

71. I'm talking about the thread I linked to earlier..

that's where the 1% number initially came from.

Glad you're at least trying to understand how reactors work. Seems like if you're going to be pimping them constantly, it's the least you can do.

What did you want to tell me about delayed neutrons? That engineers take advantage of them to maintain the 1 to 1 critical reaction?

[girl gone mad]

73. I feel like we got somewhere here.

At the start of our conversation you were telling me all fission had stopped in the reactors and that the only source of heat was the lingering decay heat.

Now I feel like you at least understand that fission is still ongoing, and, since you brought up delayed neutrons, maybe you even understand that the rate of fission is dependent on the geometric arrangement of the uranium.

If I could just get you to take the next few logical steps and realize that at higher than normal reactor temperatures, the fuel rods can melt out of their normal geometric arrangement, which is designed to keep the critical reaction controlled by absorbing those delayed neutrons "just in time" whilst allowing excess neutrons to escape.

Then maybe you will accept that if the neutrons aren't being absorbed as desired by the control rods and by the injected boric acid for any number of reasons, and if the sea water is a better moderator than the light water, or if an increase in heat and pressure (as is happening) speeds up the reaction (in some reactors the opposite will happen): there will be an increase in fission.

With any increased fission will come a rise in the thermal output (heat, or temperature, all interchangeable in this context).

Then you should accept that until you understand the answer to these variables, you don't know precisely what the thermal output of the cores is.

That is all I am asking, really.

[girl gone mad]

78. Oh, and for the record..

decay is a "nuclear reaction". It involves changes in the number of protons and neutrons, which reside in the nucleus of an atom. The only reason I specified "nuclear reactions" in my post is that it is possible that some of the chemical reactions (interactions involving the electrons in the atoms) are also generating heat, but my point was that almost all of the heat is being produced by reactions in the atomic nuclei. I mistakenly assumed you were intelligent enough to understand why I was making that distinction.

I notice you like to nag at insignificant aspects of my posts while ignoring the substantive points I'm making. This tactic makes you come across as petty and simple-minded.

[FBaggins]

80. For the record... No... You're still dead wrong.

Like all those neutrons produced with decay?

But thanks for the ongoing free entertainment. The gift that just keeps on giving.


I notice you like to nag at insignificant aspects of my posts while ignoring the substantive points

Oh you have GOT to be kidding. The entire argument was you tying to nag at insignificant aspects to avoid the simple reality that fission is NOT what is creating the heat in those reactors. There has been no heat of ANY consequence from fission since very shortly after the reactors were shut down.

They could cool all the heat being produced by fission, by having someone with emphysema blow hard on it. :rofl:

[girl gone mad]

81. I like that you keep kicking this thread.

So more people can see what an idiot you are.

[FBaggins]

32. Lol. A little knowledge is a dangerous thing GGM.

Spontaneous fission is your answer now? Do you know how rare that is?

7.0x10^-11. That's basically saying that for every 15 billion decays you get one spontaneous fission.

Fission is still ongoing and will be for weeks, at least.

Nope. Fission ended immediately after the earthquake.

Where does the arrogance come from?

Ignorance often mistakes competence for arrogance. I don't mean to come accross that way, but you've made some very simple errors and seem immune to correction. This isn't a matter of opinion or something we can meet half way on. How would you prefer that I correct you?

[girl gone mad]

34. No, the fission did not end. Where do you guys come up with this stuff?

You don't get partial meltdowns with no fission. Do you understand anything at all about nuclear reactors?

Here, I found a tutorial that might be just your speed:

http://www.google.com/url?sa=t&source=web&cd=10&ved=0CGEQFjAJ&url=http%3A%2F%2Fmitnse.files.wordpress.com%2F2011%2F03%2Ffission_02.pdf&rct=j&q=nuclear%20fission%20temperature%20correlation&ei=HVyJTYHsO62C0QGuxen2DQ&usg=AFQjCNG3GXAZvt0bsI9uNX0UcbCgwOCXwQ&cad=rja

[FBaggins]

37. It's simple physics.

I'm really sorry GGM. You seem to think it's open to debate... it simple isn't.

You don't get partial meltdowns with no fission.

That's flat wrong. Decay heat may be a small fraction of what you get from fission in the same core, but it is easily enough to cause a meltdown.

Here, I found a tutorial that might be just your speed:

Lol. If you'll turn to page 2-24 in that tutorial... you might learn something. The last paragraph explains what I've been trying to tell you. Note that the reactor has been shut down. The next couple pages will be useful for you as well. Fission declines rapidly from the moment the reactor is shut down. The chain reaction ends faster than you can read this thread.

[girl gone mad]

42. Guess you didn't make it to the end.

A reactor “scram” (or “trip”) is the rapid (two to four seconds) insertion of the control rods into the core to stop the fission chain reaction. Even though all of the fissioning in the core is not stopped, the chain reaction is broken down, which causes a significant decrease in reactor power in just a few seconds. When the reactor is shut down (all rods inserted), the amount of heat being generated due to the fissions which are not stopped and the decay heat is much less than that which can be removed by the plant systems. Therefore, the fuel can be protected from an over-temperature condition.

It's not difficult to shut down the critical reaction. That's actually the easy part.

[FBaggins]

44. That's the first few seconds.

Fission doesn't stop instantaneosly is what they're saying. But it drops off really rapidly.

Are you honestly trying to tell me that you read those pages and you're sticking with your story?

In theology that's called "invincible ignorance".

[girl gone mad]

45. I'm not the one who didn't know the difference between fission and critical reaction..

until 5 minutes ago.

[FBaggins]

48. There's a whole list of things that you didn't know

And have yet to admit even though we both know that you've now read them and are grasping at straws.

didn't know the difference between fission and critical reaction..


Lol... and what are you basing that on?

[girl gone mad]

50. You clearly have an agenda..

and you're going to try to spin.

Unfortunately, the facts aren't on your side on this one.

[FBaggins]

54. Yep. In this case it's helping people out of unnecessary ignorance.

Sorry you had to fight it so hard. :)

You REALLY think that spontaneous fission is going to cause a meltdown? That it's the real source of the heat?

Really?

[girl gone mad]

75. I think you are still missing big pieces of the puzzle.

These reactors are actually designed to allow most of the neutrons emitted in the radioactive decay to escape. This is why you have small cylinders of uranium stacked in a long tube, tubes spaced out at specific distances.

When you get to a state where the fuel is melting out of this spatial arrangement and into larger masses, the rate of fission will increase.

I am trying to keep it simple, but one also needs to consider some of the other variables that have been altered, such as the salt in the sea water, the oxidation of the zirconium, the water levels, the temperature (heat), the status of the control rods. These things (and more) will all impact the rate of fission over various cross sections of the core. Essentially, you've got stochastic processes occurring in regions which may be out of configuration and could potentially undergo chain reactions, producing more heat and more decay products, reducing the effectiveness of the boron-10, maybe leading to further disruptions.

[FBaggins]

76. Aw gee... I appreciate you trying to keep it simple. Allow me to reciprocate.

The rate of spontaneous fission does not change.

It doesn't change when temperatures increase
It doesn't change with the configuration of the mass
It doesn't change when there is or isn't water around
It doesn't change with the status of control rods or reactor poisoning
It doesn't change whether it's inside a reactor or outside.

and it's an entirely insignificant amount of activity. It has nothing at all to do with the temperature in the core right now. It's impact is zero to several decimal places. Essentially all of the heat comes from nuclear decay - as you've been instructed several times.

What can change with those factors is actual sustained fission. But none of that is going on in those reactors.

You were simply wrong. And that's as simple as I can make it.

On edit - Just noticed this one "These reactors are actually designed to allow most of the neutrons emitted in the radioactive decay to escape."

Lol... how many neutrons do you think come from radioactive decay in a reactor core?

The hits never stop.

[girl gone mad]

77. You are a lost cause.

It's like trying to teach a butterfly to swim.

[FBaggins]

79. I'd imagine so

Especially when you've never seen water.

[girl gone mad]

82. Says the man who:

doesn't know that fission and critical reaction are different concepts,

doesn't understand that the primary source of the heat energy responsible for the rise in temperature is the nuclear reactions,

doesn't understand that radioactive decay is a nuclear reaction,

doesn't understand that spontaneous fission can cause incidents of induced fission in a reactor that has partially melted down,

doesn't understand that variables such as the temperature and density of the moderator will effect the rate of fission,

but wants to play a physicist on the internet.

[girl gone mad]

41. How many uranium atoms are in the cores?

Now be sure to also do the calculations for all of these alpha particle-emitting decay products of uranium:

Pr-231, Th-227, Ra-223, Rn-219, Po-215, Bi-211

Now tell me that you know the precise configuration of the U-235 in the reactors at this moment. How do the containment rods look? Are any of them defective? Does the sea water thermalize neutrons as effectively light water? Less? More? How well did the boric acid work? How corroded are the components? What effect is this corrosion having?

Bottom line: you cannot tell me how much fission is occurring in those reactors.

[FBaggins]

47. You really think it matters?

I gave you the proportion of decay events that result in SF. Roughly one event out of 15 billion.

Every single one of those 15 billion gives off heat. You really think you can compare that to SF?

What percentage of the heat generated in the core do you think comes from SF in that event?

Pr-231, Th-227, Ra-223, Rn-219, Po-215, Bi-211

This just highlights your error.

Do you know what the half-life of Po-215 is? How much of the stuff do you think it in the core a week and a half after it's shut down?

Half of the Radium and a third of the Thorium is gone, essentially all of the Bismuth and Radon are gone as well as all of the Polonium.

Bottom line: you cannot tell me how much fission is occurring in those reactors.

Actually... I can. It's zero (to several decimal places).

SF isn't limited to reactors. It happens anywhere you have Uranium... but it's entirely irrelevant to the discussion. It doesn't add 1% to the amount of heat generated in a shut down reactor. It doesn't add a hundredth of a percent... or a thousandth or one millionth of a percent.

[girl gone mad]

55. Yes, all of those things matter.

When you get uranium melting out of the controlled configuration, you can get clumps of uranium and increased fission. It's incredibly important to know how well the boron-10 is working. Control rods fail - it happens in normally functioning reactors. With any increase in fission, you get an increase in heat and an increase in decay products, which could lead to more fission and more heat. Does the heat slow the reaction or increase it under current parameters? Also important to know.

You cannot say "I know the rate of fission is 0.000000" with no data to support that assertion.

[FBaggins]

56. Sigh.

You cannot say "I know the rate of fission is 0.000000" with no data to support that assertion.

I've given you the data. Your refusal to understand it really doesn't rise to the level of "my problem". Sorry.

You've got a decimal place followed by a looong list of zeros before another digit... and you're comparing it to a whole number and acting like the incredibly tiny number is the one driving the bus. That's just ridiculous.

With any increase in fission, you get an increase in heat and an increase in decay products

Oh lordy... there you go again. Neither heat nor fission change the rate of decay.

Once again GGM... there is no sustained fission reaction going on in those reactors. SF happens regardless of where the uranium is. It is a non-factor in this event.

[girl gone mad]

61. Well, at least you learned about spontaneous fission.

I guess that's a start.

You do understand that the fission involves the emission of neutrons, right?

Once those neutrons are emitted, they can be absorbed by other uranium atoms, causing more fission.

Get it?

This is the reason that uranium is kept inside of rods, spaced out at specific distances inside of the core.

[FBaggins]

63. Wrong.

You do understand that the fission involves the emission of neutrons, right?

Yep.

Once those neutrons are emitted, they can be absorbed by other uranium atoms, causing more fission.

And how often does that happen?

Hint. If it isn't a sustainable chain reaction... you're right back where you started. Comparing a whole number to a bunch of leading zeros.

[girl gone mad]

66. How often that happens depends on how the uranium is configured.

It doesn't have to be an ongoing critical reaction or a chain reaction to generate a lot of heat. Chernobyl never got back to critical, but it got extremely hot and they had full meltdown.

[FBaggins]

70. Oh lordy... it never stops.

Chernobyl never got back to critical, but it got extremely hot and they had full meltdown.

You're kidding, right?

Chernobyl didn't shut down. Not only did it not need to "get back to critical", it powered UP as it failed.

It was at significantly ABOVE full power as it melted down.

The hits just keep coming with you, don't they?

[girl gone mad]

72. Well, it was way before my time..

maybe I'm thinking of 3 mile isle., but my other point remains. When you get the fuel melting into an uncontrolled configuration, the rate of fission and heat output will increase.

[Confusious]

74. Depends upon how the Uranium is configured?

Care to explain that?

Also care to tell us if you have any sort of science degree?

[ReturnoftheDjedi]

5. Frodo, those are external reactor temperatures

http://www3.nhk.or.jp/daily/english/23_10.html

If the outside of the reactor is over 700 degrees Fahrenheit, it's not that far of a stretch for the core to be well over a thousand.

Your excuses are beginning to pile up. And things just keep getting hotter...

[FBaggins]

9. External to the core vessel, not to the building.

They don't need to restore temperature sensors to read the temperature on the outside of the building... you can buy one of those at a kitchen store.

[ReturnoftheDjedi]

13. right. external to the core, not internal to the core.

inside it is far hotter.

[flamingdem]

4. That's an increase from earlier today, No. 1 is in trouble, they weren't watching

it as closely but now it's critical.

[jpak]

6. Partial meltdown - and the possibility of recriticality and pressure lock

yup

[kristopher]

7. The previous discussion

You see here the casing in the reactor one building and you see the heat signature here, the yellow and red. In reactor one, the government says the Ministry of Defense says the highest temperature 58 degrees centigrade so about 136.4 Fahrenheit the government say, what does that image tell you?

ARNIE GUNDERSEN, NUCLEAR SAFETY ADVOCATE: I don’t believe the highest temperature is anywhere near that. It’s probably much nearer to thousands of degrees, but — what it does show me is you’ll see sort of like a line, a straight line of hot material.

So the claim at the time of the thermal imaging was that #4 was at 136F.
Gundersen says this isn't likely, the appearance is "probably much nearer to thousands of degrees".

Now the reported temperature is said to be 715-735F.

I suspect this number is accurate as they expected to get solid data once they had power hooked up.

BTW, they have the lights on in the Central Command Center of #3.

[flamingdem]

11. Thanks for the reminder, Gundersen is probably correct on the high temps

You can take what Tepco says and almost double it for the truth.

And they "don't know why" the radiation is still high and smoke coming out...

[kristopher]

17. Likewise the nuclear supporters here.

Have they been even close to accurate on anything to date?

[flamingdem]

19. Strangely many of the experts on CNN and MSNBC

are fairly honest. Gundersen has been on CNN, Roberto Alvarez on Rachel's show, Jim Walsh on CNN didn't coat the truth much.

They realize what's at stake in perpetuating a lie or putting a happy face on such a disaster. I wish that someone competent would take over the accident.

[CRH]

8. Clarify what it means to run at 302C, ...

Does than mean when it is in normal operation with no rods inserted or is that a cold shut down state.

[FBaggins]

10. That's normal operations

Give or take a little bit.

[flamingdem]

12. Do you mean normal for an operating Nuke or normal for a cold shutdown Nuke? nt

[ReturnoftheDjedi]

14. snap

[FBaggins]

16. Normal for an operating nuke.

Remember that the vast majority of the heat generated in normal operation is drawn out to generate power.

[CRH]

22. If 302 is normal for when no control rods are inserted to stop the reaction, ...

Then the rods were inserted to stop the fission and even with the salt water douche the core continues to heat? It sounds like a whole lot of water is failing into steam or the vessel is slightly breached and leaking.

[FBaggins]

23. Nope. Really very little reason for concern there.

The cores continue to produce heat, but that amount has fallen substantially. They can only get the temperature down by adding cooler water and removing some of the heat (either by pumping out hot water or by letting off steam). Since the circulating pumps aren't working, they can't just cycle the water through a "radiator", they would have to let out steam.

And every time they do that they're releasing radiation into the air (and have to stop work around the plant).

The temperature WILL continue to build up until they do one or the other. But they can certainly control it.

What this really means is that they'll have to release steam from that unit again (unless they can get circulation going pretty quickly)... which means that radiation levels at the plant will spike again and they will have to evacuate many of the workers for a time.

[CRH]

26. So until the decay stops, venting steam is the only recourse, ...

short of a complete repair of the pumping system. The obvious problem is these pumps are very sophisticated, not well suited for salt water, and can't be readily found at the hardware store. And, the pumps are but a part of the cooling system. It sounds like a lot more releases of steam and radiation, because there isn't a likely quick fix to the cooling system, if you can even get close enough to make the repairs. If the first ten days has allowed half the cesium of Chernobyl, the next three months accumulation could be quite significant. This is only one reactor core.

[FBaggins]

27. Yes... but less and less frequently.

Nothing really changed from a few days ago except that the cores produce less and less heat as the days go by... so these exercises become less and less frequent. On two of the three units, they can delay even further by letting the steam flow into the torus... but as we saw in the early days of the crisis, this just delays things until the temperature in the torus reaches 100. And on one unit even that doesn't appear to be an option.

They also have the option of timing the releases to better coincide with weather patters that will take the steam over the ocean and with work schedules of those on site.

[ReturnoftheDjedi]

29. do you really think these things are cooling down?

things aren't going according to plan.

stop being so dense.

they aren't venting steam because it is too radioactive. if they did it, they would have to evacuate, yet again.

[FBaggins]

31. Cooling down? No.

They're producing less and less heat... they don't "cool down" unless somebody cools them.

they aren't venting steam because it is too radioactive. if they did it, they would have to evacuate, yet again.

And since that's exactly what I've said (three times?), what point do you think you're making.

[ReturnoftheDjedi]

33. if they can't release steam, how do they relieve pressure?

they can only put so much water in if there is already steam buildup present.

how do they cool things down???

?????

[FBaggins]

36. Who said they can't release steam?

They don't WANT to release steam, but they have done so a number of times.

They have another option depending on the temperature of the water in their pressure suppression chamber, but eventually they have to either ciculate water (cooling it outside of the reactor and pumping it back in) or they have to release steam.

As I said... that should be (and has been) less and less frequent as the heat produced by the core drops, but it will continue to happen until they restore some kind of circulation.

It doesn't have to be a disaster. They need to time it for a period where few workers are on the site and when the winds are blowing and release out to sea.

[CRH]

40. Reactor #1 might be the least of the problems, Work stopped at # 2, 500 millisieverts/hr at plant.

Other thread in this forum.

[FBaggins]

43. I think it probably IS the least of their problems.

Not counting 5&6 of course.

It's just that some people take whatever the most recent news is and assume THAT is the big problem.

Work stopped at # 2, 500 millisieverts/hr at plant.

I saw the thread but haven't seen a better report yet. Still waiting. If it was a planned steam release than they knew about it in advance and got out of the way... but the thread implies (without explanation) that they "discovered" the radiation. Par for the course for how some of these things get reported. I suspect we'll know more soon enough.

But yes, I've said for awhile that #2, while it appears to be the least damaged, may be the greatest cause for concern. While containment doesn't appear to be breached, some of the effects are the same. They can't let steam into the pressure suppression chamber because it wasn't holding pressure. I interpret that to mean that the steam would be released without going through the normal filters that reduce the amount of radioactive materials in the steam. The steam itself is highly radioactive, but that activity dissipates very quickly.

[Statistical]

39. Temperature isn't thermal output. Thermal output isn't temperature.

The thermal output of each reactor will decline predictable according to nuclear decay. The bad news is there is NOTHING anyone can do to speed it up. The good news is that there is nothing short of a recriticality event that would reverse this decline in thermal output.



Right now thermal output (think energy) of reactor is about 0.2% of peak. That sounds good but you have to remember reactors 2-5 are 780MWe. To produce 780MW of electricity requires about 3x as much heat. So ballpark it is about 2400MWt. 0.2% is 4.8MWt. Fat better than 2400MWt (peak forced fission) but 4.8MWt is a lot of energy. Most people don't think of heat in megawatts so lets convert it to BTU. 4.8MWt = 16,378,279 BTU/hr. A home furnace is about 60,000 BTU. So if you ran your home furnace for a single hour it would produce 60,000 BTU/hr. This is almost 300x as much and it never turns off.

Temperature is based on the ability for that thermal output (energy) to be removed from the core. Temp of a system is the different between energy in and energy out. Your furnance has a thermal output (maybe 60,000 BTU). The temp in your house if the combination of energy in (thermal output of furnace) and energy out (heat transfer via conduction through walls). If it is really cold outside it might be cold in your house despite a higher thermal output of your furnance and likewise if it is warmer outside it could be warmer in your house despite a lower thermal output from your furnace.

This isn't a fire. You can't put it out or end it faster. The thermal output (energy) of the core will continue to decline. However to avoid the temp in the core from rising the workers must ensure the energy flow OUT of the core is greater than the energy flowing INTO the core (from nuclear decay). Air is an ineffective heat transfer mechanism. Water is a good mechanism to transfer heat. If the ability to transfer heat away from the core is LESS than the current thermal output then temp will rise. If it is greater than thermal output then it will fall.

As far as venting. As thermal output declines over time (which it will, it is impossible for it to not), the amount of energy that needs to be removed from the core will also decline. Energy is removed via steam, so the amount of steam which needs to be vented will decline also. There are a couple reason for NOT venting steam. As pressure builds the boling point of water rises. higher boiling point means it takes more energy to boil the same amount of water. Why is that useful? Remember the core has a certain amount of thermal output which is energy. The workers need to remove that. At higher pressure each unit of water removes more energy from the core thus they are more effectively using water to transfer heat from the core to the atmosphere.

So the plan is something like this
1) close vents
2) inject water into core
3) intentionally allow pressure to rise making boiling point higher and cooling more efficient
4) conduct work while vents are closed.
5) when pressure gets too high you can't pump more water in (pressure in core exceeds pressure of pumps)
6) recall workers
7) vent steam
8) repeat

Continually venting (not allow pressure to build) would do nothing except
a) make working on the site more difficult
b) REDUCES the effectiveness of the cooling which would lead to even higher temps
c) consume even more water

[CRH]

53. OK, so you evacuate the workers, ...

Then release pressure through venting steam. This steam has been said to be highly radioactive, but dissipates rapidly. Does this mean the steam doesn't travel far, or that the radioactivity falls to the ground and is no longer airborne? This steam does contain Cesium and Iodine isotopes if the core is damaged, correct? So by dissipating rapidly, does that mean it ends up on, in or near the plant, but not airborne?

[Statistical]

58. The steam is mostly volatile isotopes.

Xenon, Tritium, Iodine, Argon, Krypton etc. Isotopes with very low vapor pressures. Luckily these isotopes tend (there are some exceptions) to either have short half-lives or they are lighter than air and don't bond with other elements. The amount of heavier isotopes expelled in controll venting is minimal. No system is perfect though so some heavier isotopes will "escape" as solids being expelled out with rising gases. There are filters designed to further trap particulate matter (but that won't stop volatile isotopes) to further reduce the amounts but I have no idea if those are still functioning or how effective they are.

"It can contain Cesium and Iodine isotopes if the core is damaged, correct?"
It can. The amount would depend on level of CURRENT core damage. If the core partially melts and solidifies the amount of those isotopes being released *should* decline. Some will be expelled with the steam but since they can't vaporize (at least not at the temps and pressure in a reactor) it tends to keep the amounts low. As temp in core rises and core begins to liquify the % of release that is made up of heavier isotopes will also increase. Not just Sr-90, I-131, and Cs-137 but eventually U-235/238, and Pu-239/240 as well. That would require significant temperatures inside the core though and/or fuel rods burning.

The good news is that most of the isotopes of iodine and Cesium are short lived. The exception being Cs-137 which is pretty bad stuff due to its strong decay energy and half life of 30 years (long enough to stick around, short enough to do a lot of damage).

Look venting radioactive steam is never preferred option but the choices are venting steam (mostly noble gases with short half lives) or core melting (release of lots of very long lived bad stuff). By controlling the venting the operators can minimize the amount of non-volatile isotopes and build core pressure to improve cooling.

[CRH]

67. Thank you for the info, n/t

[flamingdem]

57. Reactor 1 is over 400-degrees Celsius. Rising fast 11:51pm EST

Just out from IAEA: Reactor 1 is over 400-degrees Celsius. Rising fast http://bit.ly/e7lout

Use google translate with this link:

http://www.yomiuri.co.jp/national/news/20110323-OYT1T00...

[CRH]

65. So it is up 10 degrees celsius in three hours, ...

Soon they will vent. It appears they just vented #2, as radiation spiked.

It will be interesting to see how much venting and then re injecting salt water will cool down #1, and for how long.