Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[TCups]

I have updated the page at http://gyldengrisgaard.dk/fuku_docs/plant/

It now includes maps of the northern as well as of the southern part of the Daiichi plant.

For those others who, like me, may be somewhat perceptually impaired (and not red-green color blind), here are the roof lines of the reactor buildings and turbine buildings . . .

 

[artax]

Gunderson on the unit 3 explosion.

 

[WhoWee]

not from me. I'd rather they give a range than give unrealistically 'accurate' numbers and then change them arbitrarily. It is highly unscientific, and imo bad for disaster mitigation as well, not to know the ranges. In disaster mitigation you have to address the range of possibilities rather than a single number. Same for the safety.

I understand your complaint and think rowmag makes a good point.

 

[artax]

I'm not sure if this was posted already. Sorry if it was.
Blueprint - http://www.houseoffoust.com/fukushima/blueprint.html

Even if it was it's good to have again... I've gone back to look for things in this thread and it's taken AGES to find!

 

[artax]

For those others who, like me, may be somewhat perceptually impaired (and not red-green color blind), here are the roof lines of the reactor buildings and turbine buildings . . .

Cheers, that's much clearer!

 

[georgiworld]

Gunderson on the unit 3 explosion.

Gunderson first states that integrity of the RVP was maintained and the fuel pool was empty, it then got filled with gas and exploded upward. He then goes on to say that the radioactive debris that was found afterward were part of the plume of the fuel pool.

Well was it empty or not?

Can someone clear this up?

 

[TCups]

Gunderson on the unit 3 explosion.

Interesting. Has it actually been confirmed pieces of fuel rods were found 2 miles away? If so, then does it seem curious that the FHM would still be in the SFP? How much of the fuel would have to undergo "prompt criticality"? Is it likely that after a prompt criticality, some of the pieces of fuel rods would be scattered miles away, yet most of the spent fuel or remains thereof remain in the SFP? Wouldn't the shock wave be transmitted to the fuel in the SFP more efficiently if it were still submerged or partially submerged? Is it likely that the source of the shock wave was simply from hydrogen in the upper floor -- what was the term? -- "conflagurating"? -- , or from an "explosion" from within the primary containment venting laterally through the transfer chute, or both? What, if anything, fell on the NE part of Bldg 3? If the conflaguration caused the "explosion" and if a fireball means "explosion" and the fireball was the first thing seen on the video, does that make sense? Boom, boom, boom. . . more and more questions.

Gunderson may be correct for all I know, but there seem to be several things yet to be explained.

 

[artax]

Gunderson first states that integrity of the RVP was maintained and the fuel pool was empty, it then got filled with gas and exploded upward. He then goes on to say that the radioactive debris that was found afterward were part of the plume of the fuel pool.

Well was it empty or not?

Can someone clear this up?

I'm pretty sure he means EMPTY OF WATER, we discussed this a while back, but I think he's right about the H2 explosion and vertical component of the blast being caused by the shape of the SFP, but I don't agree about nuclear explosion, just fuel rod debris from the (already) severely degraded fuel elements was ejected by the Hydrogen blast.

@ TCups, there's been no official release confirming the fuel outside the buildings,... but a few different sources have suggested this... have we determined where that 1SEIVERT/HR piece of concrete came from... was it 5 inch thick or cms?

and yes... more questions! I still want to know why that number 3 blast was so HUMUNGOUS!

 

[PietKuip]

Gunderson on the unit 3 explosion.

Interesting theory: a hydrogen explosion in the spent fuel pool caused a prompt criticality.

Gunderson refers to the fact that fuel fragments were found up to 2 miles from the site. Does anyone here know a source for that?

 

[RealWing]

http://www3.nhk.or.jp/daily/english/27_28.html



I would have estimated 50-75%. Units 3 and 1, which operated slightly longer, could have greater percentage than Unit 2. Burnup distribution is the unknown here. Unit 1 has 400 assemblies, while Units 2 and 3 have 548 assemblies.

I would agree with the 50-75% probability. You can be sure there will be more of statements like these: “We revised the core damage data because some readings on the containment vessel monitors were wrong,” Matsumoto said. “There was also a recording mistake. We are investigating why this happened.”

Anyway - We all really won't know for sure the amount of core damage for a few years until someone looks inside the RPV's..

 

[ascot317]

Interesting. Has it actually been confirmed pieces of fuel rods were found 2 miles away?

Not to my knowledge. He's not giving a source for this unusual statement. Something like that would have been caught in the "web" here.

 

[Rive]

Gunderson may be correct ...

Actually I think he is missing the point again, this time with the position of the SFP (it's not on the south part of the building).

 

[artax]

Interesting theory: a hydrogen explosion in the spent fuel pool caused a prompt criticality.

Gunderson refers to the fact that fuel fragments were found up to 2 miles from the site. Does anyone here know a source for that?

The first I saw of it was a report by the nuclear something council! I'll search back the required 300 pages tomorrow!

I posted something along the lines of "have a look at this" or "anyone seen this"
Around page 220 or thereabouts.

Another more recent report I read said when they first moved in with the fire trucks to start pumping they had to bulldoze over some very hot areas before the workers could venture further.

I'll find that tomorrow too... off home for a nice beer!

 

[Rive]

Actually I think he is missing the point again, this time with the position of the SFP (it's not on the south part of the building).

Well, to prevent misunderstandings: the SFP is not on the destroyed side of U3.

That'll do

 

[clancy688]

Gunderson refers to the fact that fuel fragments were found up to 2 miles from the site. Does anyone here know a source for that?

A NRC-report:

The document also suggests that fragments or particles of nuclear fuel from spent fuel pools above the reactors were blown “up to one mile from the units,” and that pieces of highly radioactive material fell between two units and had to be “bulldozed over,” presumably to protect workers at the site. The ejection of nuclear material, which may have occurred during one of the earlier hydrogen explosions, may indicate more extensive damage to the extremely radioactive pools than previously disclosed.

http://www.nytimes.com/2011/04/06/world/asia/06nuclear.html?_r=2&hp

 

[htf]

Gunderson refers to the fact that fuel fragments were found up to 2 miles from the site. Does anyone here know a source for that?

I remember that this has been reported at the very beginning of the crisis shortly after the explosions. It was in the TV - I was hospitalized that time and watching TV the whole day long.

Does it make much difference whether it was a caused by a nuclear chain reaction or a ordinary chemical reaction? The frighting scenario is that fragments of spent fuel have been widely distributed by this explosion.

 

[PietKuip]

The data that Gunderson reported on the uranium concentrations is at http://www.llrc.org/ - a graph by Busby.

He uses interesting EPA data, with many isotopes:
http://www.epa.gov/japan2011/docs/rert/radnet-cart-filter-final.pdf

All very reminiscent on the Swedes coming with the first data on Chernobyl fallout.

 

[Guest Member]

Two robots sent into the reactor No. 1 building at the plant yesterday took readings as high as 1,120 millisierverts of radiation per hour.

http://www.bloomberg.com/news/2011-04-27/tokyo-water-radiation-falls-to-zero-for-first-time-since-crisis.html

 

[Astronuc]

Recovery and rubble at Fukushima
27 April 2011

http://www.world-nuclear-news.org/RS_Recovery_and_rubble_at_Fukushima_2704111.html

 

[ascot317]

A NRC-report:
http://www.nytimes.com/2011/04/06/world/asia/06nuclear.html?_r=2&hp

So is Gunderson basing it on hearsay of an ominous NRC report, did he get to see that report, is it maybe even available somewhere? And: how does the NRC know about it?
The NYT is talking about 1 mile, he's talking about 2 miles. Rumours work that way.

 

[clancy688]

So is Gunderson basing it on hearsay of an ominous NRC report, did he get to see that report, is it maybe even available somewhere?

I saw that report. Here it is, page 10:

http://fukushimafaq.wikispaces.com/file/view/rst+assessment+26march11.pdf

 

[PietKuip]

Does it make much difference whether it was a caused by a nuclear chain reaction or a ordinary chemical reaction? The frighting scenario is that fragments of spent fuel have been widely distributed by this explosion.

A sudden fast criticality would have heated the fuel from within. The fuel pellets would have had high temperatures, and would have spread more uranium, plutonium, and other non-volatiles than a chemical explosion.

So yes, that is quite a difference.

It is still speculation, of course. But if a fast criticality is a possibility in a spent fuel pool, it is also possible that it got triggered by a steam explosion.

 

[|Fred]

So is Gunderson basing it on hearsay of an ominous NRC report, did he get to see that report, is it maybe even available somewhere? And: how does the NRC know about it?
The NYT is talking about 1 mile, he's talking about 2 miles. Rumours work that way.

it was posted some post back
http://cryptome.org/0003/daiichi-assess.pdf


Fuel may have been ejected from the pool (based on information from TEPCO of netron sources found up to 1 mile from the units, and very high dose rate material that had to be bulldozed over between units 3 and4. It is also possible the material could have come from Unit 4)

 

[ascot317]

I saw that report. Here it is, page 10:

http://fukushimafaq.wikispaces.com/file/view/rst+assessment+26march11.pdf

Thanks

Fuel pool is heating up but is adequately cooled, and fuel may have been ejected from the pool
(based on information from TEPCO of neutron sources found up to 1 mile from the units, and
very high dose rate material that had to be bulldozed over between Units 3 and 4. It is also
possible the material could have come from Unit 4)

That's quite different from "fuel found 2 miles away". Blegh.

 

[PietKuip]

I saw that report. Here it is, page 10:

http://fukushimafaq.wikispaces.com/file/view/rst+assessment+26march11.pdf

That talks about neutron sources, not fuel.

(I suppose one keeps some californium neutron sources around at nuclear reactors, to do measurements of criticality factors maybe?)

 

[GJBRKS]

That talks about neutron sources, not fuel.

(I suppose one keeps some californium neutron sources around at nuclear reactors, to do measurements of criticality factors maybe?)

.

Spoiler

... and very high dose rate material that had to be bulldozed over between units 3 and 4...

 

[clancy688]

.

Spoiler

... and very high dose rate material that had to be bulldozed over between units 3 and 4...

Plus those 300 and 900 mSv chunks they found near Unit 3 this week.

 

[Bandit127]

Please forgive my ignorance here, but could someone shed some light on the data in the following TEPCO report:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110427e18.pdf"
Unit 1 (for instance) has a "Core Damage Ratio (Drywell)" of "approximately 45%". Does this mean that approximately 45% of the core is in the Drywell? And (it follows) that approximately 10% is in the wetwell?

TIA.

Jim

 

[Samy24]

Please forgive my ignorance here, but could someone shed some light on the data in the following TEPCO report:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110427e18.pdf"
Unit 1 (for instance) has a "Core Damage Ratio (Drywell)" of "approximately 45%". Does this mean that approximately 45% of the core is in the Drywell? And (it follows) that approximately 10% is in the wetwell?

TIA.

Jim

There are books that show analyses of a core meltdown. Estimates to the amount of molten core can be made as a reference to the CAMS readings. The higher the readings the higher is the expected core damage. A link of this report was published a hundreds of post before.

Extremely high values can indeed indicate a melt through the RPV.

 

[clancy688]

There are books that show analyses of a core meltdown. Estimates to the amount of molten core can be made as a reference to the CAMS readings. The higher the readings the higher is the expected core damage.

I don't think that's his question. In the pdf he posted there are two assessments: Core damge (drywell) and Core damage (wetwell) for all reactors.
But core damage inside the dry- and wetwell is imho pointless - that's not damage anymore, but molten corium... or am I misunderstanding something?

Drywell = Inner containment, hull around the RPV
Wetwell = Torus, condension chamber