Monday, February 13, 2012

Reactor 2 RPV Bottom Temperature at Support Skirt Junction Also Fluctuating Widely

The location whose thermocouple (69H1, bottom head) apparently broke after the resistance test by TEPCO yesterday and the location at the support skirt junction are both located at 0 degree.

The thermocouple at the support skirt junction, 69F1, is not spiking up or continuously trending up like 69H1, but the range of fluctuation is rather wide, compared to the other two at the same height at different angles.

Hmmm. Next to go?

From the latest plant parameter on Reactor 2 RPV temperature, hourly, 69H1 (bottom head at 0 degree) and 69F1 (support skirt junction at 0 degree) highlighted:

Hourly temperature fluctuation at the thermocouples at the support skirt junction:

69F1 (at 0 degree): by 0.1 to 11.7
69F2 (at 135 degrees): by 0.1 to 0.3
69F3 (at 270 degrees): by 0.1 to 0.2

By the way, TEPCO released the graph of the thermocouple 69H1 (2/13/2012). It sure looks like TEPCO's resistance test did something:

People are chiming in on Japanese Twitter, saying "Yes I've done exactly that, pushing one test too far..."


farfromhome said...

Could it be that the radiation and high heat are damaging these instruments?? How much are they designed to take?

Anonymous said...

Ask Quince the Robot. He is entombed at 2.

arevamirpal::laprimavera said...

If they are sound, thermocouples should have no problem above 500 degrees Celsius, I hear. Depends on the types of course. It turns out that only 2 of the 40 or so thermocouples on the Reactor 2 RPV were found to be functioning. 1 was broken, and the rest were considered good enough if they were calibrated, though they sustained some damage when the RPV was heated to a very high temperature in the early days of the accident.

They are not designed to be exposed to extreme temperature, and certainly not designed to work in a humid environment.

farfromhome said...

Thank you, kind of what I thought, they are not made for the conditions they are in.

It seems it might be a good idea to come up with some 'thermometers' that can handle all of the conditions - i.e. extreme heat, humidity and radiation - and get them in these reactors pretty darn quick.

Oh that's right, human's can't get in there to install them, nor can poor robots like Quince last very long. :(

Very awe inspiring...

Chibaguy said...

No one in their right mind would not consult the manufacturer. I guess we know where TEPCO stands.

Anonymous said...

And what about these thermometres

Yestarday 93,7 °C at "CRD housing upper part" and at "RPV Bottom Part (Wall Above Bottom Head)"

Are they booken too?

Anonymous said...

It looks more and more probable that there is either water or corium flowing down in that particular sector.

Anonymous said...

When looking at the summarizing graph with the temperatures for unit 2, it seems that at the same time when T at the RPV bottom part started to increase slowly, T at the "RPV drain pipe upper part" (yellow dots) started to decrease and now almost reached zero, close to environmental level. Just mere coincidence or could there be a correlation? Maybe this gauge is broken as well?

Anonymous said...

Physics Forum has information on the number of nonfunctional temperature sensors in Unit 2.
See: and scroll down to comment #12364. There are links to news reports of TEPCO testing sensors---two more bad sensors found, for a total of 8 non-functioning sensors in Unit 2.

But much worse than that is the detection of XENON GAS in Unit 2 in the next comment.
See: Xenon detected in unit 2:
or TEPCO's press handout from this morning

NOW what???

Anonymous said...

I can't stand that place, the so-called "experts" on Physics Forums which including the resident nuke engineer, besides being obtuse and anal about the whole catastrophe, made quite clear that no criticality was possible after the fuel's loss of geometry and mods gave out warnings or deleted posts from anyone that suggested it.

The resident nuke and the other mods there should apply for a job with TEPCO. They've already been extremely useful to them.

Anonymous said...

It's not just the moderators on PF that are anal, so are many of the posters there and one annoying naval nuke idiot comes to mind. In almost every post he repeats ad nauseum how the lessons from Fukushima will now be implemented into nuclear reactor safety around the globe...

FUCK OH YEAH, YOU BRILLIANT EINSTEIN, so explain the NRC Chair Gregory Jazcko"s sole no vote on the Vogtle license, warning that the proposed time frame would not allow lessons from Fukushima to be incorporated into the reactors' design.

Does the nuke mafia specially handpick these naive egotistical dumbasses as employees?

Anonymous said...

Somebody pulled a Homer on that resistance test.


Anonymous said...

Some arrogant prick on PF just dissed Enenews. It's just headlines...says he. That's the mentality there. They need made up data from TEPCO so they can feverishly start calculating the erroneous and irrelavent.

Anonymous said...

Yes, I understand about the academics at Physics Forum and all that implies. However, I read lots and lots of sites trying to gather any grains of truth about what is really going on.

Tonight on Physics Forum someone sent in a paper on re-criticality due to re-flooding with water. And guess what, looks like re-ciritcality is back on the table over there.

Here's the last comment:
"This paper certainly seems to fit the bill pretty well. It suggests that recovering the fuel with water has in fact quite a powerful impact on the potential for criticality, which is certainly news to me. That implies that the future performance of this facility is in fact somewhat unpredictable, rather than being bounded by the decay heat curve. It also means that getting a good handle on the distribution and location of the fuel in these reactors is of more than academic importance."

Also I noted in the last two daily Plant Status Reports TEPCO is now listing Hydrogen Density.
Unit 1 is 0.01% and Unit 2 was 0.07% on Feb 13th and 0.08% on Feb 14th. This is of significance, isn't it?

Atomfritz said...

In the physicsforums there was a large thread (several hundred posts) that got very close to the nuclearists' taboo that recriticality could have occurred, and even could have been taken part in the big explosion of unit #3.

This thread got deleted.

But, is this so difficult to understand what possibly happened at Unit #3?
(It is quite obvious that nuclear proponents try to not look at this possibility as if it were Medusa's face.)

The absorber and control rods begin to melt away like candle wax at around 800 C.
The fuel rods/assemblies can stand a far higher temperature.

Large part of this lattice of fuel assemblies could have still stood when the reactors were re-watered.
What does this mean?

The water now would have moderated and enabled a chain-reaction in the parts of the reactor where the fuel assembly lattice still was intact, void of the molten-away moderator and shutdown rods.
When the water level reached a particular height, the submerged core part would have reached a super-critical state. Some time later an uncontrolled chain reaction sets on, leading to a rapid criticality excursion, a minuscule nuclear deflagration.

Kaboom! Water hammer! Tubes breaking! Metals sparking and igniting the oxyhydrogen mixture! Kaaabooommmm!

Ivan said...

Very possible scenario, Atom. You describe very well.

Atomfritz said...

And now imagine the possibility that the water level in a such damaged reactor like Unit #2 could rise after changing the cooling regime.
Which could covering a larger part of the core, and lead to a super-critical situation there as described above.
Obviously, nobody wants another "shutdown" reactor to go kaboom.
Maybe actually this risk worried Tepco sufficiently to again introduce expensive boron into the reactor?

Ivan said...

They are worried about this for sure otherwise, yes, why so much adding expensive neutron absorber to (LOL) cold shutdown. Nuke industry scientists are habitually saying recriticality is not possible(they just assumed all fuel geometry melted right away)but they don't know much of anything about what is going on with fuel. What you describe it's very plausible, actually something I am afraid can happen. I'm hoping not.

Anonymous said...

Don't diss the PF thread. Lots of EXTREMELY good info and analysis in there, although the bias is decidedly pro-nuke.

But what do you expect? The experts all work in the field. They tend to be bright people, who would have chosen a different career if they didn't believe in a bright future for nuclear power (and for themselves, by consequence).

Anonymous said...

There is good technical info on PF but one has to ask, "Analysis of what?

The attitude baffles me. For the first 500 pages of the nuke disaster thread well meaning people were shot down and ridiculed for suggesting TEPCO was obfuscating and their numbers were skewed. People without any expertise in the nuke field connected the sorry dots much faster than the experts. What I've learned from PF is that experts(who checks their credentials anyway) can't think beyond their noses and compassion seems to be sorely lacking. I also learned that I had a heated exchange with a regular there who turned out to be a bloody highschool kid.

Anonymous said...

Many PF residents are pro nuke, to be sure. If nothing else, they make for good, stiff, technically competent opposition..

But it really was funny/sad to see them eat their words in the first few days.

"Oh they're designed not to blow"
pop goes reactor one
"oh it was a fluke, god damn it, they'll get the power back on and it'll be fine"
boom goes number three
"well, shit. at least the worst is over"
containment breach at two, fire in containment at three. oops.

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