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Nuclear Open Thread

Fukushima Technical Discussion Open Thread

It was suggested in a comment — and I agree — that the previous open threads on the Fukushima Daiichi Nuclear Accident were becoming difficult to read, because they are such a mixture of technical details and philosophical discourse. That is, it’s generally a bad idea to cater to two different audiences in one comment thread. So, I will split them up.

Please restrict all discussion here to technical information, analysis, criticisms and questions on FD — no philosophising or excursions into whether nuclear power is ‘good’ or ‘bad’ or the implications of FD for the future of nuclear power (except for new technical developments, e.g. safety standards), etc. You may impart your deep wisdom on how the world should work on the other open thread I’m about to open.

Besides the above guidelines, the other rules of the Open Threads on BNC apply. Read here for details.

To kick off discussion, below is the latest FEPC status report (I’ll update this as new reports come in). You will also be interested in:

— JAIF Updates #35 and #36

— NISA Major Parameters 0600 March 29

— NISA Summary Conditions 0600 March 29

—————-

  • Radiation Levels
    • At 11:45PM (JST) on March 28, TEPCO announced that plutonium 238, 239 and 240 were detected in the soil sampled on March 21st and 22nd at five spots in Fukushima Daiichi Nuclear Power Station. Concentration of detected plutonium 238, 239 and 240 are the same level of the fallout observed in Japan at the atmospheric nuclear tests in the past and poses no major impact on human health.
    • At 6:30PM on March 29, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 177 micro Sv/hour.
    • At 6:30PM on March 29, radiation level at west gate (approximately 3,609 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 120.2 micro Sv/hour.
    • Measurement results of environmental radioactivity level around Fukushima Nuclear Power Station announced at 7:00PM on March 29 are shown in the attached PDF file. English version is available at: http://www.mext.go.jp/english/radioactivity_level/detail/1304082.htm
    • For comparison, a human receives 2,400 micro Sv per year from natural radiation in the form of sunlight, radon, and other sources. One chest CT scan generates 6,900 micro Sv per scan.
  • Fukushima Daiichi Unit 1 reactor
    • At 1:00PM on March 29, pressure inside the reactor core: 0.371MPa.
    • At 1:00PM on March 29, water level inside the reactor core: 1.65 meters below the top of the fuel rods.
    • At 1:00PM on March 29, pressure inside the primary containment vessel: 0.265MPaabs.
    • At 1:00PM on March 29, the temperature of the reactor vessel measured at the water supply nozzle: 570.9 degrees Fahrenheit
    • As of 3:00PM on March 29, transferring the water found at the turbine building to the condenser continues.
    • As of 4:00PM on March 29, the injection of freshwater into the reactor core continues.
  • Fukushima Daiichi Unit 2 reactor
    • At 1:00PM on March 29, the temperature of the spent fuel pool: 114.8 degrees Fahrenheit.
    • At 1:00PM on March 29, pressure inside the reactor core: -0.025MPa.
    • At 1:00PM on March 29, water level inside the reactor core: 1.5 meters below the top of the fuel rods.
    • At 1:00PM on March 29, pressure inside the primary containment vessel: 0.1MPaabs.
    • As of 4:00PM on March 29, the injection of freshwater into the reactor core continues.
    • As of 7:00PM on March 29, approximately 96 tons of water in total has been injected into the spent fuel storage pool.
  • Fukushima Daiichi Unit 3 reactor
    • At 12:00PM on March 29, pressure inside the reactor core: 0.029MPa.
    • At 12:00PM on March 29, water level inside the reactor core: 1.85 meters below the top of the fuel rods.
    • At 12:00PM on March 29, pressure inside the primary containment vessel: 0.1075MPaabs.
    • At 2:17PM on March 29, TEPCO began to shoot freshwater aimed at the spent fuel pool, with a specialized vehicle normally used for pumping concrete, until 6:18PM (approximately 100 tons in total).
    • As of 4:00PM on March 29, the injection of freshwater into the reactor core continues.
    • As of 7:00PM on March 29, approximately 4,697 tons of water in total has been shot to the spent fuel storage pool.
  • Fukushima Daiichi Unit 4 reactor
    • At 11:50AM on March 29, lighting was restored in the Central Control Room.
    • As of 7:00PM on March 29, approximately 960 tons of water in total has been shot to the spent fuel storage pool.
  • Fukushima Daiichi Unit 5 reactor
    • At 2:00PM on March 29, the temperature of the spent fuel pool: 101.5 degrees Fahrenheit.
  • Fukushima Daiichi Unit 6 reactor
    • At 2:00PM on March 29, the temperature of the spent fuel pool: 70.7 degrees Fahrenheit.
  • Fukushima Daiichi Common Spent Fuel Pool
    • At 3:10PM on March 28, the temperature of the spent fuel pool: 95 degrees Fahrenheit.
    • As of 7:00PM on March 29, approximately 130 tons of water in total has been injected to the spent fuel storage pool.

By Barry Brook

Barry Brook is an ARC Laureate Fellow and Chair of Environmental Sustainability at the University of Tasmania. He researches global change, ecology and energy.

368 replies on “Fukushima Technical Discussion Open Thread”

Do the detectors used for official readings reported around the 40km area detect alpha particles? If not, does this pose a yet unknown risk for human or food chain contamination – if – these particles are inhaled or ingested? Alpha particles are scattered then land but are easy to disturb, on trees, on cars, doors, or just about any object sitting outside. Even relatively small amount of localized particles if inhaled or ingested is dangerous to human health. Yet they can go undetected by large area detectors. Ive read that most geiger counters don’t detect alpha particles very well, or at all. I’m trying to understand the nature and danger of alpha particles.
http://en.wikipedia.org/wiki/Geiger_counter
MODERATOR
Your double up post was deleted. Please do not post the same comments on more than one thread.

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harrywr2, on 5 April 2011 at 12:10 AM said:

While the analogy with a car and tree was a bit strained, this is the exact point.

Can the shield building, do precisely what you suggest with realistic scenarios?

Either Tom Keens referenced 9,500lb at 350mph

or my 5000 kg at 140 m/sec? [500km/hr]

This is a simple, rigorous, objective question.

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@ Shelby:

Alpha particles are emitted by atomic nuclei in the radioactive process known as alpha decay. They consist of two protons and two neutrons bound together by nuclear forces, and are therefore in fact helium nuclei travelling at high velocity. Alpha particles radiated by decaying radioactive atoms will soon attract electrons, becoming neutral helium atoms (all helium gas on earth has been produced by radioactive decay in this manner).

Alpha particles are highly ionising, but cannot penetrate materials very well. They are stopped by a peice of paper, or the surface of skin, and only penetrate a few centimetres through air, after which they have been slowed down to normal velocity for atmospheric gas and are inert helium atoms. Alpha radiation emitted by external sources is therefore quite easy to sheild against. Alpha radiation is much more dangerous if it is emitted internally. The chief hazards associated with alpha emitting materials come from injecting, inhaling or ingesting them.

So it’s not alpha particles themselves we’d be worried about, but particles of alpha-emitting materials.

Alphas can generally only be picked up by a Geiger counter if the detector has a mica window (like mine).

No doubt there are all sorts of detectors on hand to measure the radiation present at Fukushime.

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I would be thrilled to death if you guys could stick a little more to the crisis at hand.

There are 2 important questions to answer:

1) What is the FLOW RATE (GPM or pick your units) of the most radioactive water source .)

2) and

MOST IMPOTANTLY: where is it coming from.(presumably from R2)

My dumb guess is that it is coming from the torus of R2. It may be coming from some amount of leakage from control rod seals but we do not know for sure.

I am hopeful it is just stagnant water from the torus from when the reactor was venting early on in the crisis.

GSB

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@Martin Burkle, on 5 April 2011 at 11:12 PM said:

Since Will Davis did not bother to state the precise measurement, I guess we will never know if those readings are any higher than the others.

It is amazing how someone can write an entire page about something with so little specificity. I ignore those blogs myself, but that’s a personal choice. I prefer the data here, which is stated succinctly and in commonly measured units for comparison.

Barry did not even pay me to say that :-)

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George Bower, on 5 April 2011 at 11:42 AM said:

What is the FLOW RATE (GPM or pick your units) of the most radioactive water source

Outflow can’t exceed inflow for long.
According to NISA the amount of water being pumped into the reactors.

Click to access en20110404-4-3.pdf

6 m3/h to reactor #1
8 m3/h to reactor #2
7 m3/h to reactor #3

Tepco map of seawater readings, range of 14,000Bq/cm3 at the scrren for Unit #4 to 300,000Bq/cm3 at the screen for Unit #2
Readings in the aea of the ‘cable pit’ go as high as 5,400,000bq/cm3.

Click to access 110405e31.pdf

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> Will Davis
Apparently that’s from TEPCO; here is the same number:

“By Kenji Hall and Julie Makinen, Los Angeles Times
April 5, 2011, 4:39 a.m.
Reporting from Tokyo—
The operator of Japan’s stricken Fukushima nuclear plant said Tuesday that it had found radioactive iodine at 7.5 million times the legal limit in a seawater sample taken near the facility, and government officials imposed a new health limit for radioactivity in fish.
The reading of iodine-131 was recorded Saturday, Tokyo Electric Power Co. said….”

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> Outflow can’t exceed inflow for long.

I’d doubt that in this case — it could be there was already leak water under the plant before this event, undetected.

I’d guess the trenches and pits are below the current water table.

After the tsunami, water that soaked into the ground is probably flowing through the ground toward the ocean — and whatever cracks or leaks in the concrete are letting some of the radioactive water mix with the groundwater flowing through.

So I’d guess you can’t assume the outflow is all water that was put onto the plant.

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George Bowers on April 5th suggests that the leakage into the sea is from the Unit 2 torus. The torus are below grade. Assuming that the there is leakage from the torus into the reactor building, there would need to be a running pump to lift water out of the basement of the reactor building.

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Harry quote:

“Outflow can’t exceed inflow for long.”

Totally agree. Some is going of in steam but probably a small percentage.

They need to restore CLOSED LOOP cooling of all the RPV’s and cooling ponds.

Only ten will they be able to pin point where this minor leak is.

BTW: another speculation :

Unit 2 seems to be using another 2 M3 / hr of make up. Just a dumb thought that that could be the drainage from the torus and/or whatever small amount might be coming from control rod seals.

The final failure analysis of this incident should be very interesting!!
GSB

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The New York Times has found a report dated March 26th written by the NRCs team of specialists. The Times article is at http://www.nytimes.com/2011/04/06/world/asia/06nuclear.html?pagewanted=1&ref=todayspaper
Claim #1
NRC experts are really worried about aftershocks now that both the reactor vessel and the containment vessel are half full of water. This might cause a large break in plumbing or the containment vessel.
Claim #2
Reactor #1 is clogged up by the use of sea water. I think they mean that water can no longer flow freely around the rods. Therefore, there is high danger that the fuel is not where it used to be.

I did not see a link to the “found” report.

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Ted, from my understanding, recriticality is not an impossibility, but the evidence Gunderson presents is not compelling. The chlorine-38 was puzzling but I haven’t seen any reason why sodium-24 was not also detected, under the theory that seawater was in a neutron field. The tellerium-129 is simple – it has decayed from Te-129m, a higher-energy but longer-lived version of the same isotope. You can even see it on the next line of the assay. The “neutron beams” are poorly sourced and not well explained by anything.

Basically we are accustomed in the confusion of Fukushima to half-stories that have no immediate explanation. Gunderson seems to be using a selection of those to try to prop up his story of Fukushima as “Chernobyl on steroids”, a wild and irresponsible speculation he was spreading early on.

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@ Chris Warren

I don’t know why you are persisting with this line of argument. It is wildly out of perspective with other much more serious and pressing hazards (e.g. climate change) or even attacks on any hazardous chemical plant. Did you go to google scholar and search “nuclear power” and “aircraft”?

The EPRI document is the publication of a study. A $1 million, rigorously reviewed study, apparently – performed by a non-profit energy research consortium, none the less.

“that nuclear energy production is the safest form of current energy production.”

Your insertion of “current” validates my concerns.

How does that validate your concerns? Nuclear power has killed, and does kill, less people per unit of energy produced than any other form of energy production. I substantiated this claim upthread. Do you have evidence to refute this, or not?

Your claim that the study is somehow fallacious is unsubstantiated, again.

Once more, I urge you to put the risks of nuclear energy into the context of climate change, and into context with the many other risks of not replacing fossil fuels. Not to mention the reality of poverty due to much of the world’s population having insufficient access to energy.

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Times article on new threats to plant safety at Fukushima, according to confidential NRC report.

The case for nuclear power does not depend on what happens at Fukushima. With that in mind, we should not make overconfident statements about how all will turn out there.

what do others think?

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Gregory Meyerson, on 7 April 2011 at 1:01 AM said:

Times article on new threats to plant safety at Fukushima, according to confidential NRC report.

The case for nuclear power does not depend on what happens at Fukushima. With that in mind, we should not make overconfident statements about how all will turn out there.

what do others think?

——-

As a journalist, I have a folder with hundreds of over confident assurances and predictions. I think it’s too late to cover up. Going forward, I think experts need to focus on the questions people are asking, and give answers that include the full array of potential risks and outcomes. People want experts to distill information and technical jargon down to language that the average intelligent person can understand. I’m not an engineer, but after reading hundreds of technical reports about nuclear power and about this crisis, I’m finding very little problem understanding technical concepts, if they explained properly. The confusion arises from engineers and experts that try to hide certain aspects, while highlighting aspects that support their beliefs. Eventually, after all is said and done, good journalism will weed out those that gave accurate explanations, from those who gave clouded explanations to support their beliefs. We mainly depend on the experts to explain and distill the facts. All of the facts. All of the risks. Anyone with good reasoning skills can then review the information and make critical observations and reports. We don’t need experts to make our critical observations and reviews for us.

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I would add, I think the NY Times has overall done an excellent job of critical reviews and responsible reporting.

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harrywr2, on 6 April 2011 at 4:57 AM said:
6 m3/h to reactor #1
8 m3/h to reactor #2
7 m3/h to reactor #3

In my morning search for news I do not see anywhere what the makeup rate for the reactors is.

I am wondering if now TEPCO is recirculating the water in the RPV via a rigged (portable) recirculating pump.

Also thanks.

Hank Roberts
Hank Roberts, on 6 April 2011 at 8:42 AM said

for the plant schematic that shows that the turbine basement is on the same level as the torus:
http://geospatial.blogs.com/.a/6a00d83476d35153ef014e87077d90970d-320wi

Another interesting thing to notice from this schematic is how deep the water must be in the turbine basement. In order for the water to come out the top of the vertical shaft the turbine basement would have to be around 3/4 full, putting the top of the water in the basement much higher than the Torus. This leads me to think that the majority of the water in the basement is from the spraying of the spent cooling ponds.

I still would like to know how much water is leaking out the seals of the control rods though….and where this contaminated water goes. From what I mentioned above it must not be going into the turbine basement.

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Shelby, on 7 April 2011 at 2:35 AM said:

Times article on new threats to plant safety at Fukushima, according to confidential NRC report.

I would be alarmed if a safety review failed to identify possible problems. That’s the purpose of safety reviews, identify potential problems so actions can be taken to insure those problems don’t occur.

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> for the water to come out the top of the vertical shaft

George, did you see a description or picture somewhere saying that water came out of the top of one of the trenches?

According to the descriptions, the cable trenches carry power down to the seawater pumps at the edge of the ocean. The water was entering one of the trenches through a big crack in its side and then running down to the ocean, from the descriptions I’ve seen.

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Hank,

The picture I saw was on WSJ where the TEPCO person in a hazmat suit is pointing to a crack in the slab at ground level on the plant grounds.

If you look at the schematic you posted here:
http://geospatial.blogs.com/.a/6a00d83476d35153ef014e87077d90970d-320wi

I think the verticle shaft which is fed from the trench below the turbine basement is where the source of contaminated water was coming from. So it would be turbine room to trench below turbine room to verticle shaft to cable trench then out thru crack (now sealed) to ocean.

Is that your understanding??

Thx,
GSB

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The link below should take you to a copy of the NRC report. Of course I cannot be 100% sure it is the original, you can judge the material yourself. It does mention the interesting “fact” that neutron sources were found 1 mile from the reactors and that neutron sources between units 3 and 4 were covered with materials moved by bulldozers. The report speculates that the material came from reactor # 3 spent fuel pools.

https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=0BzIU3Bd_MTpFMmI4MTlhMGUtOTc0MC00NTRiLWJiMTktOTNjOGEzZmIyNzdl&hl=en

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Thx Harry,
interesting schematic of how they are injecting the Nitrogen. Looks like normally they inject into the torus but in this case they are injecting into the CV and exiting out the torus.

Questions for anyone on a slightly different subject:

1) Where is all the make up water going?? Is it just coming off in steam??

2) If there is leakage from the RPV from (for example the reactor seals) where does this water end up?? I thought days ago that it was going into the turbine basement but now I am not sure as the turbine room seems to be filled up to a level much higher than the torus.

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George Bower, on 7 April 2011 at 7:16 AM — For #1, it seems that all makeup water goes to steam as #1 continues to hold pressure. Alas, not so for #2 & #3 so some of the makeup water for those units may be leaking out.

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@ steve lapp 6:14AM

I think the NRC was saying they didn’t know where the neutron sources were coming from (spent fuel pools of Unit 3 and Unit 4 were their primary suspects).
In the assessment portion of Unit 3 your source says the neutron sources bulldozed between 3 and 4 could be from Unit 4 and in the assessment of Unit 4 it says the sources could be from Unit 3.

Not complaining. Just want to avoid overstating their case.

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@ steve lapp 6:14AM

The NRC report contents are peppered with industry acronyms, some of which are challenging to outsiders like myself. One document I’ve found helpful is a work-in-progress report for procedures for the Swiss Leibstadt BWR: Development Of Leibstadt NPP Severe Accident Management Guidelines For Shutdown Conditions (SSAMG).

Leibstadt is a recent, larger BWR with Mark III containment, so please don’t take this as a severe accident plan for Fukushima R1, R2, R3.

Here is a sample of relevant english-acronym correspondence:

The Emergency Core Cooling System (ECCS) of the Leibstadt plant is composed of seven subsystems: one High Pressure Core Spray (HPCS), one Low Pressure Core Spray (LPCS), three Low Pressure Core Injections and two Special Emergency Heat Removal (SEHR) systems. HPCS is the backup system for the steam driven Reactor Core Isolation Cooling System (RCIC). Once the RPV level cannot be maintained by the high pressure injections systems (feed water, HPCS, RCIC) or a failure of these sytems occurs, the Automatic Depressurization System (ADS) will activate in order to allow low pressure systems (LPCS, LPCI) inject into the RPV. LPCI is one of the Residual Heat Removal (RHR) modes. The other two important RHR modes for accident mitigation are Suppression Pool and Fuel Storage Pool Cooling.

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All three Daiichi units are on fresh water “feed and bleed”. Why doesn’t the hot fresh water dissolve the accumulated salt deposits. I.e., the salt that is inhibiting contact between fuel and coolant water flow?

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George, I don’t see the leak described or pictured — that’s why I asked if you had a source for what you say is happening other than logic and reasoning.

The latest info describing the crack/leak to the sea — at http://www.iaea.org/press/?p=1972 — says something more complicated than the simple cross-section picture — a leak path was via “… a series of trenches/tunnels used to provide power to the sea water intake pumps and supply of service water to the reactor and turbine buildings….”

Those aren’t shown on the simple diagrams.

That IAEA bulletin suggests some of the flow into the pit is from groundwater, I think — blocked by filling holes near the pit in the ground with “liquid glass” (“water glass” — sodium silicate — which sets up as a gel).

My guess has been there’s lots of water in the ground, under and around the plant, now draining toward the ocean, some of it carrying radiation sources from somewhere. I’d be not surprised if some radiation is found from earlier spills that went unreported, detected by the current attention.

But that’s just my guess. If there’s radioactive material in the groundwater, they’ll find it by drilling more holes further away, eventually.

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George, here’s more — found at
http://atomicpowerreview.blogspot.com/2011/04/further-on-fukushima-daiichi-monday.html
image is attributed to NISA:

Mostly speculation, but by someone with some knowlege. Excerpt follows:

“… We have a new, section view of the piping at the Fukushima Daiichi No. 2 plant showing, again, the pipe trench or tunnel and the electrical conduit. This is provided by NISA.

Again, TEPCO isn’t sure of the flowpath of water into the pit. It is starting to seem, from various releases and statements that there might be other ways the water is getting into the ocean. One might guess that if the cracks in the concrete are deep, perhaps water flow has begun to create pockets or spaces and perhaps established other flowpaths to sea. My point in mentioning this is that TEPCO probably also thinks the same thing ….”

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Steve Darden, on 7 April 2011 at 9:03 AM said:

The NRC report contents are peppered with industry acronyms, some of which are challenging to outsiders like myself.

This is a feature of their mentality. Economists also invent their own jargon. Post-modernists also construct their derived discourses in much the same way (or is ‘way’ to be understood ie deconstructed as ‘discriminated discretionary direction’?)

The more jargon, acronyms, and inconsistent pet-nouns, – the more dubious is the source.

Now, not even a simple concept as High Level Waste has content.

I have always included spent fuel as high level waste. Not so – apparently.

ANSTO now say Australia has no high level waste!

What about spent reactor fuel – one may ask?

ANSTO = “That is not high level waste”

see: ANSTO No HLW

So what should we call spent fuel –

“higher than high level waste” ?

“uber waste”?

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Better image for the leaky cable trench — the pit is at the intake point at the ocean, according to this:

Source: http://www.japan.org/archives/1257

“According to the utility and the Nuclear and Industrial Safety Agency, the square, concrete-covered pit is situated near an intake used to pump seawater into reactor No. 2.

Although the pit is small, it contains highly contaminated water with a radioactivity exceeding 1,000 millisieverts per hour that is leaking into the ocean from a 20-cm crack, Tepco said.

The pit, which is 1.2 meters x 1.9 meters and 2 meters deep, is usually used to store cables. But it is also connected directly to the reactor building through a cable trench, raising the possibility that the source of the contaminated water is the reactor itself, a NISA official said.

The cable trench is different from the pipe trench at No. 2, where water with the same level of radioactivity was discovered Monday. Although the two trenches are connected, no water has been found in the cable trench because it is at a higher elevation, the official said….”

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Chris Warren, technically complex subjects require precision in language. But the ANSTO link you cite gives a plain English explanation of the spent fuel situation that does not support your tendentious reading.

To quote:

Are the spent fuel rods stored at ANSTO high level waste?

International and national standards do not consider spent fuel as waste.

I’m sure you would like to call the fuel plates removed from the reactor “high level waste”, but the fact is that they are valuable articles, and valuable materials can be extracted from them. They are not in any sense “waste”.

The processing of these fuel plates is (unfortunately) done overseas. The ultimate waste stream is categorized as “intermediate level waste”.

This information is in plain English on the page you cite, and on one of its sister FAQ pages:

ANSTO| OPAL and research reactors

So what should we call spent fuel –

“higher than high level waste” ?

“uber waste”?

Given that the terms you have offered clearly do not describe the nature of the material, do you have any sensible suggestions?

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The US definition:
http://www.nrc.gov/waste/high-level-waste.html

“High-level radioactive wastes are the highly radioactive materials produced as a byproduct of the reactions that occur inside nuclear reactors. High-level wastes take one of two forms:
Spent (used) reactor fuel when it is accepted for disposal
Waste materials remaining after spent fuel is reprocessed”

The IAEA definition according to Australian material:
http://msowww.anu.edu.au/~peterson/dest_gov_au_radwaste_australia_amounts.html

“High level waste
The International Atomic Energy Agency defines high level radioactive waste as waste material that generates heat at rate of greater than 2,000 watts per cubic metre. … Nuclear power reactors generate larger quantities of radioactive waste at higher levels of radioactivity than research reactors. Australia’s reactor does not generate high level radioactive waste.”
—–

Actually useful number: 2000 watts/cubic meter.

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@ Chris Warren

It depends what type of spent fuel you are talking about. the OPAL reactor uses about 30 kg of low-enriched uranium (~ 20 % U-235) to produce 20 MW. The spent fuel is not classed as high level waste. This is not based on some arbitrary industry jargon, but simply on how radioactive it is!

I believe the HIFAR reactor (now closed) did produce some high level waste, but was sent to France for reprocessing. It is due to be returned to Australia in 2015 as intermediate level waste.

Source: http://www.aph.gov.au/library/pubs/bn/2007-08/RadioactiveWaste.htm

“higher than high level waste” ?

Why distort facts like this?

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John Morgan, on 7 April 2011 at 12:20 PM said:

Whether spent fuel plates are high-level waste or not, surely, must depend on their isotope concentrations and associated need to insulate from the environment and humans.

In general, I have understood, strictly that HLW included – spent fuel. I have not encountered this definitional drift. The HLW (Spent fuel) is clearly described in the NRC Backgrounder, here:

http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/radwaste.html

which states:

HIGH-LEVEL WASTE

High-level radioactive waste is uranium fuel that has been used in a nuclear power reactor and is “spent” or is no longer efficient in generating power to the reactor to produce electricity. Spent fuel is thermally hot as well as being highly radioactive, requiring remote handling and shielding.

I assume that OPAL spent fuel plates are “thermally hot as well as being highly radioactive, requiring remote handling and shielding.”

So I think we should include spent fuel as high level waste.

If there is some technical reason, then what is it? So far the ANSTO position only gives them a philosophical comfort of being able to tell the public;

“ANSTO produces no high level waste.”

but their logic applies to all nuclear reactors – not just OPAL.

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@ Chris Warren:

High-level radioactive waste is uranium fuel that has been used in a nuclear power reactor and is “spent” or is no longer efficient in generating power to the reactor to produce electricity.

OPAL is not a power reactor.

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The actual grading of radioactive waste is determined by standards set locally by national nuclear regulators, and is not the same word wide.

For example the US does not recognize a separate category for medium level waste, but the EU, and some other countries do. On the other hand the US has a classification for Transuranic waste (TRUW) which, as defined by U.S. regulations is, without regard to form or origin, waste that is contaminated with alpha-emitting transuranic radionuclides with half-lives greater than 20 years, and concentrations greater than 100 nCi/g (3.7 MBq/kg), excluding that which is defined as High Level Waste.

As well some regulators maintain sub classes (A,B.C etc) within a particular category further confusing the issue.

Thus arguing what and what is not High Level Waste is a sterile exercise, as the definition depends on jurisdiction.

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@Steve Lapp 7 April 6:14 AM

Thanks so much for the NRC report. With that, the BNC, the Areva slides and the ordinary TEPCO/JAIF/IDEA info, the situation inside the R1-3 RPV/PCV and SFP is much clearer. Also info on SFP #4 H2 explosion.

@ George Bower 7:16 AM and David Benson 7:29 AM:

The NRC document indicates that on R1-3, the recirculation pumps (located inside the PCV) likely have had pump seal failures. Pump seal failures can result in RPV liquids leaking thru the damaged pump seals into the PCV D/W and torus, and over time could fill the PCV to the level of the pump seals. Not all the water pumped into the RPV would have to go out as steam, it could leak too. The RPV would still be intact.

Example R-1 & R2: “Recirculation pump seals have likely failed (R-1 GE – Hitachi) (R-2 Industry)” . R-2 & R-3: ” Based on the reports of RPV level at 1/2 core height, the reactor water level is believed to be even with the level of the recirculation pump seals, implying the pump seals have failed.”

If a PCV is damaged (as in R-2?), then leakage of radioactive water from PCV to the secondary containment building etc is possible.

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Tom Keen, on 7 April 2011 at 12:35 PM said (out of context):

Why distort facts like this?

If you are going to fabricate accusations like this you had better get your facts right.

Your citation only validates my concerns, and indicates they at least date from August 1993. The Parl. Research Service document says:

The report of the Research Reactor Review examines, among many other things, the issue of the management of spent fuel rods from the HIFAR reactor, which had been accumulating at Lucas Heights since 1963. The Report says:

…
* ‘The spent fuel rods at Lucas Heights can only sensibly be treated as high level waste The pretence that spent fuel rods constitute an asset must stop’ (p. 216).

If you think HLW is based on “simply on how radioactive it is”. Then provide evidence and technical details, and advice on how relevant this is to past spent fuel and current spent fuel and future spent fuel.
MODERATOR
Your tone here is descending into “slanging match” territory. Not allowed on BNC as it tends to snowball and have a deleterious effect on the commentary. Same applies to others in this conversation.

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Finrod, on 7 April 2011 at 1:12 PM said:

OPAL is not a power reactor

This is disingenuous as no-one said this – so what is the point.

The only point of interest, is whether:

OPAL spent fuel plates are “thermally hot as well as being highly radioactive, requiring remote handling and shielding.”

There are also associated issues about past spent fuel rods and future spent fuel rods.

But there is no relevance in strange statements about OPAL being a “power reactor”.

If you want to jump to talk about power reactors – then please note that the ANSTO quote I referenced

International and national standards do not consider spent fuel as waste.

does not exclude power reactors.

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Hank Roberts, on 7 April 2011 at 12:27 PM said:

high level radioactive waste as waste material that generates heat at rate of greater than 2,000 watts per cubic metre

[deleted sarcastic personal comment]
2 kw per cubic metre is a useful benchmark.

Where (if) is it promulgated within ANSTO?

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@ Chris Warren:

This is disingenuous as no-one said this – so what is the point.

The quote is directly from your comment:

In general, I have understood, strictly that HLW included – spent fuel. I have not encountered this definitional drift. The HLW (Spent fuel) is clearly described in the NRC Backgrounder, here:

http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/radwaste.html

which states:

HIGH-LEVEL WASTE

High-level radioactive waste is uranium fuel that has been used in a nuclear power reactor and is “spent” or is no longer efficient in generating power to the reactor to produce electricity. Spent fuel is thermally hot as well as being highly radioactive, requiring remote handling and shielding.

I assume that OPAL spent fuel plates are “thermally hot as well as being highly radioactive, requiring remote handling and shielding.”

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[deleted violation of BNC’s citing rule. Please provide a link and re-post]
MODERATOR
Sorry – I was deleting as you were typing the link into your comment above. Would you like to re-submit the comments that went with the now posted link?

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While changes improved safety at the Fukushima No. 2 nuclear power plant, overconfidence, complacency and high costs stymied such action at the now-crippled Fukushima No. 1 plant, according to people familiar with the situation.

The difference in the safety designs was the main reason why the crisis continues to unfold at the Fukushima No. 1 plant–one of the oldest in Japan–while the No. 2 plant a few kilometers south remains relatively unscathed by the March 11 Great East Japan Earthquake and tsunami.

Officials at another Tokyo Electric Power Co. nuclear plant in Kashiwazaki-Kariwa, Niigata Prefecture, analyzed the differences in safety designs at the two Fukushima plants.

According to their analysis and TEPCO sources, there are clear differences in safety levels between the two plants concerning power source equipment, such as emergency diesel generators and transformers at the reactor cores, and pumps used to bring in seawater to remove residual heat from the cores.

TEPCO documents show that the emergency diesel generators located in the turbine buildings at the Fukushima No. 1 plant were flooded by the tsunami and rendered inoperable, except for the one at the No. 6 reactor. This effectively disabled the cooling mechanisms.

After the No. 1 plant lost its power sources, the reactor cores became much more difficult to control, leading to serious problems, including hydrogen explosions that damaged the housing of the reactors.

Radioactive materials have also been emitted from the damaged reactors.

No such problems have been encountered at the No. 2 plant.

The emergency generators at the No. 2 plant were in buildings housing the reactor cores. Because the reactor buildings are much more airtight, the generators at the No. 2 plant continued to function after the tsunami struck.

Emergency generators are also located within the airtight reactor core buildings at the Kashiwazaki-Kariwa plant, which has similar design features to the Fukushima No. 2 plant.

When asked about the differences in the safety designs between the No. 1 and No. 2 plants, an official at TEPCO headquarters said: “This does not mean we have admitted that a problem exists. We will conduct further detailed studies to identify the problems.”

The No. 1 plant was built in the 1960s and 1970s. Improvement work was conducted in the 1970s and 1980s to strengthen its resistance to earthquakes.

http://www.asahi.com/english/TKY201104060126.html

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Finrod, on 7 April 2011 at 2:03 PM said:

[deleted comment about another persons motives/actions]

You raised the issue about OPAL being claimed to be a power reactor.

Where in your quote posted @ 2:03 pm is there any reference to the issue you raised @1:12.

The question of OPAL being or not being a power reactor does not arise – except, and only, in your post.

I will say it again – no-one has suggested that OPAL is a power reactor.

If you are trying to make some other point – please make it clearer.

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[Amended]

This is useful. From: http://www.rte.gov.au

High level radioactive waste

The IAEA defines high level radioactive waste as waste material that generates heat at a rate of greater than 2 kilowatts per cubic metre – bout the same power as an electric kettle. Managing this waste requires special procedures to manage both the heat and the radioactivity. High level waste results from the reprocessing of spent fuel from nuclear power reactors.

The previous HIFAR reactor and the current OPAL reactor, at The Australian Nuclear Science and Technology Organisation’s (ANSTO) facility at Lucas Heights, are research reactors. They do not generate nuclear power and do not produce high level radioactive waste.

No mention of OPAL, ie Australian current spent fuel plates.

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From the NY Times article linked above by Shelby:

The Nuclear Regulatory Commission’s statement regarded unit No. 2, and the agency underscored that its interpretation was speculative and based on high radiation readings that Tokyo Electric had found in the lower part of unit No. 2’s primary containment structure, called the drywell. The statement said that the commission “does not believe that the reactor vessel has given way, and we do believe practically all of the core remains in the vessel.”

and from the article Twittered by Barry:

Martin Virgilio, a top official for the U.S. Nuclear Regulatory Commission, said at a House of Representatives hearing that the NRC did not believe that the core of Fukushima’s reactor No. 2 had melted down.

Earlier, a Democratic lawmaker had said the NRC informed him the core had become so hot it had probably melted through the reactor pressure vessel.

http://goo.gl/IqpV0 2 hours ago
It seems the Democratic lawmaker quoted before was mis-informed.

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@ Chris Warren:

If you are trying to make some other point – please make it clearer.

Sure Chris. I’ll try. You certainly have set a very high bar on the level of clarity needed to get the point across to you, but I will attempt to rise to the challenge.

In your post of 10.23 am, you complained that

ANSTO now say Australia has no high level waste!

What about spent reactor fuel – one may ask?

You received a couple of responses, including one from Hank Roberts at 12.27 pm as follows:

“High level waste
The International Atomic Energy Agency defines high level radioactive waste as waste material that generates heat at rate of greater than 2,000 watts per cubic metre. … Nuclear power reactors generate larger quantities of radioactive waste at higher levels of radioactivity than research reactors. Australia’s reactor does not generate high level radioactive waste.”

So Hank referenced a quote clearly raising the issue of the difference between power reactors and research/isotope production reactors with regard to the category of waste generated by each.

Although this should have made it clear to you that your criticism of ANSTO’s waste stream definitions was on rather shaky ground, you ignored Hank’s qoute and persisted with the following comment at 1.07 pm:

In general, I have understood, strictly that HLW included – spent fuel. I have not encountered this definitional drift. The HLW (Spent fuel) is clearly described in the NRC Backgrounder, here:

http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/radwaste.html

which states:

HIGH-LEVEL WASTE

High-level radioactive waste is uranium fuel that has been used in a nuclear power reactor and is “spent” or is no longer efficient in generating power to the reactor to produce electricity. Spent fuel is thermally hot as well as being highly radioactive, requiring remote handling and shielding.

I assume that OPAL spent fuel plates are “thermally hot as well as being highly radioactive, requiring remote handling and shielding.”

So I think we should include spent fuel as high level waste.

In light of the above, it seems clear that you completely ignored Hank’s earlier point, hence my comment.

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What does this mean?

“practically all of the core”

if they cannot say “all of the core”, what is the meaning?

How does this relate to Lahey’s earlier speculation (up thread):

“… and at least some of it is down on the floor of the drywell,” Lahey said. “I hope I am wrong, but that is certainly what the evidence is pointing towards.”

Lahey’s “at least some” is in drywell could be consistent with “practically all” being in the vessel.

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I thought the issue was a claim that OPAL was a power reactor.

OK – now … presumably another issue …

Finrod, on 7 April 2011 at 3:15 PM said:

In light of the above, it seems clear that you completely ignored Hank’s earlier point, hence my comment

Certainly not. In fact I said something like Hank’s stuff was the only useful contribution.
His posting of 2 kw was useful.

The only questions now are whether:

(or where) the ANSTO definition excludes power reactors.

(or where) the 2Kw standard is applied by ANSTO, and

what is the relevance of this to current Australian spent fuel plates that have, or will, arise from OPAL.

Is it not plausible that OPAL spent fuel is:

“thermally hot as well as being highly radioactive, requiring remote handling and shielding.” (NRC benchmark)

We just need a technical, objective, answer or reasons if no-one really knows.

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Chris Warren@3:30

What does this mean?

“practically all of the core”

if they cannot say “all of the core”, what is the meaning?

I suggest you read both articles and enquire of the U.S. Nuclear Regulatory Commission as to what they mean.

BTW it helps if you highlight, in your comments, quotes from other people and sources and state the person and time of the comment to which you refer.

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@ Chris Warren

The previous HIFAR reactor and the current OPAL reactor, at The Australian Nuclear Science and Technology Organisation’s (ANSTO) facility at Lucas Heights, are research reactors. They do not generate nuclear power and do not produce high level radioactive waste.

Yes, you said it.

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Finrod, on 7 April 2011 at 3:15 PM said:

In light of the above, it seems clear that you completely ignored Hank’s earlier point, hence my comment

Certainly not. In fact I said something like Hank’s stuff was the only useful contribution.

Anyone reading through the thread would be absolutely clear that the point of Hank’s I was refering to was the one concerning power reactors. Your attempt to dodge and shift impresses no one. In fact your sophistry is absurdly transparent.

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It might be pointless but for an undecided person like me it sure points to nuclear energy possibly not being a clean energy. Am I right in saying that there is a continuous buildup of high level waste that needs controling?

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Chris Warren may demand the details be kept private, but his public commentary speaks for itself.

The BNC commenting rule regarding questioning motivations is good. Nevertheless there will sometimes be individuals whose motivations truly are questionable. Thats the problem with rules. No formal system can be complete, and a perversely motivated individual can always find the GÖdelian hole.

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Eric Moore, the high level waste issue is greatly overstated, and rarely put in context with the really dangerous waste – CO2 from fossil fuels.

A picture might be helpful. Under the “F.A.Q” tab at the top right of the main page there is a link to a pamphlet. In the pamphlet is a photo of the dry cask storage of all the high level “waste” from 31 years of operation of a nuclear plant. Its not large. France has got about 80% of its electricity for the last thirty years from nuclear power. The waste from that energy production occupies a single (largish) room in Le Hague, where it awaits reprocessing.

If you really wanted to dispose of it, it could certainly be done – say by burying it deep in a subduction zone, or a very stable geological structure. No issue. But it would be a dreadful waste because only about 1% of the energy from the fuel has been extracted. The sensible approach is simply to hold it in storage, and either reprocess it for use in current reactors, or burn it, completely, in fast reactors.

If the waste is used in fast reactors, getting the other 99% of energy out, the waste volume for a given amount of energy is reduced by a factor of about 100. What remains is a small volume of radioactive material with a moderate half life. This will have decayed to a level of radioactivity less than that of the rocks from which it was originally mined in about 300 years. That might sound like a long time, but I’ve been in houses that are older than that.

The high level waste is remarkably small in volume for the extraordinary amount of energy it has produced, and managing, storing, or disposing of the high level waste does not present technical or engineering problems, only problems of perception and politics.

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> Leo Hansen, on 7 April 2011 at 1:25 PM said:
>> @Steve Lapp 7 April 6:14 AM
> Thanks so much for the NRC report. With that,
> the BNC, the Areva slides and the ordinary
> TEPCO/JAIF/IDEA info, the situation inside
> the R1-3 RPV/PCV and SFP is much clearer.

Thank you Leo Hansen for a good summary at your post above.

MODERATOR – are you keeping a “library/link/list” of reference material cited? A reader can do a site search for “.pdf” and “.ppt” but it’s not very easy.

Could you collect good cites when you’re passing through deleting bad stuff ‘pour encourager les autres’? Just save a text file of the good citations.

I found a link to a more readable copy of the report discussed above (it’s not upside down like the GoogleDocs pages):

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

While I hate arguments over definitions confused with reality, that’s how the world works.

Look at the huge amount of water that has washed over the reactor cores and spilled out. It’s “none of the above” near as I can tell.

It likely fits the US “… classification for Transuranic waste (TRUW) which, as defined by U.S. regulations is, without regard to form or origin, waste that is contaminated with alpha-emitting transuranic radionuclides with half-lives greater than 20 years, and concentrations greater than 100 nCi/g (3.7 MBq/kg) …”
MODERATOR
Sorry Hank – no time to do as you suggest. As a part-time volunteer it is all I can do to keep up with the moderation. I have another life to live:-)

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John Morgan

Thanks for your explanation. Well certainly perception is a problem. Having spent fuel rods on top of the reactors at Fukushima that need to be under control for several years before being safe was an eye opener to me. Maybe it is irrational. We will have to see.

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see also

“The N.R.C. report suggests that the fuel pool of the No. 4 reactor suffered a hydrogen explosion early in the Japanese crisis and could have shed much radioactive material into the environment, what it calls “a major source term release.”…”

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More news consistent with the above:
http://www3.nhk.or.jp/daily/english/07_05.html

“Evacuation standards being reviewed….
… the amount of exposure is likely to rise in these areas as little progress has been made in cooling the nuclear fuels or containing radiation leaks.
Taking into consideration the fact that the situation may be prolonged, the Nuclear Safety Commission has reviewed its guidelines using a 2007 advisory issued by the International Committee on Radiological Protection. The commission now says an evacuation advisory should be issued to prevent residents from being exposed to a total of 20 millisieverts a year….”

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Worst case scenario questions:

If the whole world used nuclear power for it’s energy needs at US levels, and all the fission products from that were continuously sprayed, fossil fuel style, throughout the surface of the planet, what would the background radiation be?
How does that compare with the radioactivity in the whole planet? Or just the first 3 feet of crust? Or in the the water of the oceans?

More realistically:
What about the fission products from just one power plant like Fukushima? Suppose a very powerful bomb, or a set of carefully placed bombs, were detonated in such a way as to pulverise all it’s radioactive inventory. What would the consequences be?

More realistically:
What if, for some crazy reason, human intervention was deemed impossible for an entire week at a normal operating plant like Fukushima just before the quake?
What could we reasonably expect to hapen with the fuel at the reactors and pools?

I know that all of these scenarios come with a probability attached, probably zero for all of them, but knowing this, would still be very interesting.

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Joao

I think the probability of a large Tsunami hitting a power station somewhere in the world in the next 100 years is probably quite high. Because it is unthinkable and inconvenient to our dreams it is discounted as unlikely. What I am waiting to see is:

I am waiting to see what the outcome of this disaster is because that is gives me a sense of scale. If we can sustain a few accidents/disasters over a period of time from Tsunamis, large earthquakes, engineering failures and possibly terror attacks and the impact on the world is low then I am going to be happy with the idea of nuclear power.

I would imagine we have to consider that the amount of reactors may grow in density around the world and may increase the possibility of multiple.incidents.

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I have a suggestion for a simple calculation that might give us an idea of how much R2’s RPV is leaking.

Calculate how much steam is being generated. For someone w/ a nuclear background, they should be able to make some assumptions on decay rate of power output of the rods. Knowing the BTU/sec that the fuel rods should be putting out one should then be able to calculate the steam generation in lb/hr. This number could then be compared w/ the last reported makeup rate into reactor 2:

8 m3/h to reactor #2, –convert to mass flow

makeup rate – steam= leakage from PRV #2

I’d do it myself but my background is BSME w/ entire career in gas turbines.

Granted a crude calculation but it would give us an idea. My guess is that even assuming some pretty high power output from the rods you will not be able to come out w/ anywhere near 8 M3/h.

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George Bower: 8 m3/hr water is 2.2kg/s and heat of evaporation is 2270 kj/kg, so evap of all 8 m3/hr is 2.2 x 2270 = 5×10^3 kj/s = 5×10^6 j/s or 5 MW.

See MIT NSE site for Reactor 2 decay heat

http://mitnse.com/2011/03/16/what-is-decay-heat/

that’s ~ 8 MW but I’d expect that TEPCO could calculate that much better than MIT and it may be about 5 MW

The interesting thing is that R2 RPV level is unchanging over days. If you injected too little water, the level would decrease. If you inject too much, the level would go up.

For level to be unchanging, either you are injecting exactly enough (unlikely) or the level istrument is not working, or you are injecting too much and there is a leak at the measured level that keeps level constant.

This last case is what the NRC memo indicates, leak at recirc pump seal at 1/2 core level.

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@George Bower, on 8 April 2011 at 2:27 AM said:

I have a suggestion for a simple calculation that might give us an idea of how much R2′s RPV is leaking.

A simple uneducated guess would be to subtract the amount of water used on unit #3 from the amount of water used on #2. They are both the same size and both shutdown at the same time.

One m3/h more is being injected into unit #2 then unit #3. 1 m3 = 264 US Gallons/h or about 4.4 Gallons Per Minute. A standard flow restricted residential shower head has a flow rate of 2.5 GPM.

MIT Nuclear Engineering estimates decay heat in Unit #2 and Unit #3 to be 8.8 MWt as of April 1st.
http://mitnse.com/2011/03/16/what-is-decay-heat/

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Leo and Harry,

Interesting calcs. Thx.

Those are two interesting ways to look at it. I had suggested in an earlier post what Harry said: ie the R2 leakage is the diff between the injection rates of R2 and R3.

The numbers give me some faith that there is not a huge whole in the bottom of #2 from a melt thru of the PV. One or two hose bibs worth of flow out of a reactor that large sounds almost manageable.

GSB

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Some of us have wondered about ‘negative’ (below atmospheric) pressure readings. An explanation here makes sense of that observation:

http://atomicpowerreview.blogspot.com/2011/04/nitrogen-inerting-drywells.html

“TEPCO is now admitting something assumed here previously; that is, that the reactor pressure vessels are not fully intact. This could allow the hydrogen that’s generated inside them to escape and build up in the drywells. Further, there seems to be very low pressure in the drywells due to condensation of core cooling water that’s leaking out as steam. This action will tend to draw a vacuum on the drywells, further enticing the hydrogen to exit any small above-water penetrations or openings (or gaps between the pressure vessel lid and vessel itself) and collect in the drywells. Hence the need to inert them with nitrogen.

TEPCO now states that the drywells for No. 1 and No. 2 plants are damaged.. the damage to No. 1 being “relatively light compared to No. 2.” This means that hydrogen that gets out of the reactor vessel due to the slight vacuum, but the atmosphere enters the drywell as well and the mixing of a concentration of greater than about 4% hydrogen (the value for burn or explosion is altered somewhat by the value of moisture content present in the air) could lead to another burn or explosion.

Put together this all sounds like a downturn, but taken each as its own fact none of them is particularly surprising and in fact the action TEPCO is taking, knowing for a fact there is serious core damage, is one of the things you’d expect them to be doing as soon as possible after higher priorities are taken care of. This may have been another good reason why TEPCO has been rushing to get access to all the normally occupied buildings and equipment spaces.”

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Hank,
I thought that the drywell was the area below the PV inside the containment vessel. I can envision that this area is not that DRY right now as PV water is leaking from seals or broken welds.

However, I am confused how there can be “damage” to the drywell. Could someone speculate what this “damage” could be and how it was caused.

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Hank,
I think they mean there is damage to the containment vessel that allows air to enter and mix w/ the hydrogen from of the PV.

I don’t quite understand this statement though:

“This may have been another good reason why TEPCO has been rushing to get access to all the normally occupied buildings and equipment spaces.”

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> how the drywells could be damaged

This label shows what’s called the drywell:

In the bit I quoted, he explains what he means — let me try to paraphrase (remember I’m just reading what you can read):

Damage to the drywell means it’s not airtight, so low pressure in the drywell (caused by condensing steam) would suck air in from outside, as well as suck hydrogen in from the reactor vessel — an unfortunate mixture.

You’ve no doubt seen the ‘condensing steam’ demonstration — put a little water into a metal can with its screw lid off, put it on a stove til steam is coming out consistently (so the air has been forced out and only water vapor is filling the space); then screw the cap on as you remove it from the heat and wait a few minutes — and the can collapses as the water condenses, lowering the pressure inside.

That’s the mechanism he’s suggesting happening, and he’s suggesting that explains why the hurry to inject nitrogen into that space.

And —
> don’t understand … “… why TEPCO has been
> rushing to get access …”

again, look at the illustration. Much of the area sharing walls with the containment vessel, on several floors of the building, is likely dark, maybe has radioactive water or dust in it, probably has debris in it, and carries pipes and wires that penetrate the containment vessel. So — if there’s an air leak letting air get sucked into the containment vessel somewhere — how do they find it? By looking. So they’d have to get into those areas.

Makes sense to me.

The only fact we know is that TEPCO is working to push nitrogen into the space. The rest is that guy’s logic — but it seems he’s thought it through and it makes sense enough to me that I posted it.

That’s all I know. Heck, it’s far more than I know.

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P.S. — reason to worry about an explosion? hydrogen and oxygen will explode spontaneously under some circumstances. Example from a Scholar search:

http://dx.doi.org/10.1098/rspa.1952.0026
Kinetics of the Hydrogen/Oxygen Reaction. II. The Explosion Region in Salt- and Alkali-Coated Vessels

and

“Hydrogen and oxygen react spontaneously to form water. When two moles of water form by the reaction of two moles of H2 and one mole of O2 a great deal of heat is released. In fact, the presence of significant amounts of these gases together is quite dangerous, since this reaction readily occurs explosively….”
http://guweb2.gonzaga.edu/faculty/cronk/chemistry/L00-index.cfm?L00resource=thermo-spontaneous

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Leo Hansen, on 7 April 2011 at 1:25 PM — Thank you for that and a subsequent addition regarding recirculation pump seals.

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Better design does make a difference.
The NEI posted a list of changes that have been made to US reactors of the same original design http://neinuclearnotes.blogspot.com/2011/04/major-modifications-and-upgrades-to-us.html
but we have a real world example of better design.
Reactor 6 is a later and better design than Reactors 1 through 5. The key difference is the air tight building around the emergency generator which saved the generation from destruction. Reactor 5, which is of the old design, lost it’s generator but a line was run from reactor 6 to 5 saving reactor 5 from the fate of rectors 1 to 4. We know the same wave hit reactor 5 and reactor 6, but the extra protection saved reactor 6’s emergency generator.
Japans root problem was not upgrading safety features of the older plants.
Better design was the difference.

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Re pulling a slight vacuum in drywells by condensing steam from the RPV: If the RPV generates steam at a rate of 5 MW, then to condense this steam over time would require the drywell and supression chamber to transfer 5 MW heat away to containment building.

I doubt that over time there is this much heat transfer. Heating the water in the supression chamber torus to 100C would have worked in the initial days, but after that, this heat sink is gone.

I’d bet that the drywell/supression chamber is still venting steam and that the pressure is above atmospheric.

The vacuum pressure readings that has people in a snit are probably the result of bad instrumentation. Of the 2 P gages in each R2 and R3, 3 show slight vac and one shows positive pressure.

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@Leo,
Heating the water in the supression chamber torus to 100C would have worked in the initial days, but after that, this heat sink is gone.

From the ‘leaked’ NRC Doc

Click to access rst+assessment+26march11.pdf

Follow guidelines of SAMG-1, Primary Containment Flooding

It would appear the procedure from the NRC involves flooding the containment building.

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> transfer 5mw of heat away

Seems to me that cooling the reactor pressure vessels below the point they’re full of live steam is a major goal, and one they don’t know when they’ll attain.

They’d apply the precautionary principle — do everything they can to avoid the known problem.

They may not know when they’ve attained condensation — except by finding they no longer need to vent steam out intentionally.

At that point they’d want the nitrogen atmosphere already established — and enough available to blow in quickly to keep the inside pressure above the final pressure they’d expect the containment to end up at when the pressure suddenly drops as the steam condensed.

As I recall — and from those demonstration videos with metal tanks — that happens fast even in a large volume, because the steam keeps the temperature evened out as it cools down toward condensation.
Have they mentioned venting steam recently?

Have you seen any mention of the temperature on the outside of the containment concrete? (I haven’t– curious if you have)

Did you factor in the temperature of the ocean from which they were pumping sea water? I’d guess the fresh water tanks on the barges are at atmospheric temperature (which was around freezing a week ago when it was snowing; maybe colder than the ocean). Did you include those volumes of cold water being pumped in — and leaking out — as part of the heat estimate?

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> flooding the containment building

Well, it sure would be interesting to see something more up to date, but I doubt if we will unless whoever leaked that one can do it again. That leaked doc, for those who haven’t clicked through, has this header:
—-
“Official Use Only RST Assessment of Fukushima Daiichi Units, Based on most recent available data and input from INPO, GEH, EPRI, Naval Reactors (with Bettis and KAPL), and DOEINE
2100 hrs 3/2612011 The purpose of this document is to provide the NRC Reactor Safety Team’s assessment and recommendations for the Fukushima-Daiichi reactors to the USNRC team in Japan. Our assessments and recommendations are based on the best available technical information. We acknowledge that the information is subject to change and refinement.”
———-

March 26th was a very long time ago.

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The NRC document clearly states in Recommendation 4: No overt action is necessary to inject into primary containment (to me this means no additional water injection).

R 5 says Vent containment to maintain containment pressure below the primary containment pressure level. This means let steam vent to avcoid too high a pressure, over 60 psig. NISA documentation
, http://www.nisa.meti.go.jp/english/files/en20110407-1-3.pdf,

says this limit is 0.427 MPag or 62 psig. Vacuum design limit is not given, but typically is ½ atmos or 7 psia.

If 8 m3.hr of water is vaporized into steam (5MW decay heat would do this see post above) and vented into the PCV, then cooling thru PCV shell can condense all of this if the cooling is 5 MW. If less than 5 MW, say 2 MW, then 40% of the steam would be condensed and 60% vented. Water level inside the PCV would increase (unless PCV leakage prevents this) and PCV water temp would be ~100C. P~ 1 atmos

My impression is that TEPCO is flying totally blind on this, with no idea of how much water is vaporized inside the RPV or how much is leaked from RPV into the PCV. I doubt that they know how much steam is being vented from the PCV or what the PCV water level is or how much water is leaking from the PCV drywell and torus into some other area

The N2 injection is simply H2 explosion CYA in my opinion.

Re injected water temp, if water is injected at ~0C, water heat capacity is 4.2 kj/kg-C so to heat 8 m3/hr water or 2.2 kg/s to 100C is 2.2×4.2×100 = 924 kj/s or .924 x 10^6 j/s or 0.9 MW. So including this sensible heating term means that vaporizing 8 m3/hr of 0C water takes 5.9 MW not 5 MW used above.

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I begin to see why there’s concern about the loads on the already damaged reactors with continuing aftershocks. Just how _many_ large earthquakes were contemplated during the lifetime of the structure, in the design and planning?

“”Large earthquakes have more, larger aftershocks,” …. “The basic rule is if you have one magnitude 9 earthquake, you can have 10 magnitude 8s, 100 magnitude 7s, and a thousand magnitude 6s.”
http://www.npr.org/2011/04/07/135220914/why-more-shaking-is-in-japans-near-future?ps=cprs

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