What happened at Fukushima Daiichi during the Japan earthquake?

[AntonL]

NHK now hints that steam may be escaping from PCV while commenting the latest video.

Footage of the No. 3 reactor building shows its roof and the upper section of the building's
southern wall blown away by a hydrogen blast

Vapor can be seen wafting from gaps in the wreckage near a pool for spent nuclear fuel rods.
Faint steam can be seen rising from twisted steel framework over what could be the upper part
of the containment vessel.

Friday, March 25, 2011 19:10 +0900 (JST)

 

[KateB]

Rethink your post http://www.nrc.gov/reading-rm/basic-ref/teachers/03.pdf" all the water that has been pumped into the reactors for the last 14 days has been boilded away, partly released to atmospher intentionally, partly unintenyionally and some condensed in the dry well and torus.

Yes, but a rudimentary heat exchange can be set up, especially if these military hoses are reinforced for use as heat exchangers (as most are). They were only inputting the system initially, with no exchange or output beyond venting (I am assuming it was thought of, but not able to be put in action)From the diagrams it looks as if there are more valves beyond the one they used to flush the system with initially, and an external heat exchange could be set up using existing plumbing (Barring that all the ductwork for the cooling system isn't compromised; is that what you are suggesting?) It isn't the best scenario, but it could work until a better system could be set up, no? Plus it could help dissolve some of those salts building up, by using the freshwater. Also, what about dilute acetic acid to dissolve some of the carbonates, etc? It has a high boiling point (in fact raises the boiling point of water in solution), and makes an excellent solvent without eroding steel or zirconium in dilute enough solutions. (though it can be corrosive to others--Be kind, remember, I am a Biochem major). The only problem I can conceive of, is that it might erode some of the concrete, but it wouldn't have to be used long term, just enough to decalcify. Please advise! I am open to criticism, I want to learn :)

 

[AntonL]

Yes, but a rudimentary heat exchange can be set up, ...
--Be kind, remember, I am a Biochem major). ... I want to learn :)

Kate no offence meant, we should be all kind and loving to each other. Just to illustrate the
enormity of the cooling problem.

Unit 1 is currently generating the heat of 2000 kettles (1000W) boiling away continually and
Unit 2 and 3 about 4000 kettles each, the same tomorrow , the day after slowly getting less
and less and be about a half the amount in 2 month time.

 

[Gilles]

sorry to have brought trouble with my post. I saw the video well before, too, but I hadn't noticed this orange fleck before I read the french thread (which is BTW rather chilling). It may well be just a piece of any orange painted material, but it seems to glow - may be hit by the sun too. I was just interested in knowing your opinion. It is difficult to identify where the shot is located - somewhere around R1 I guess, just after we see the untouched roof of R2 and then R3 and R4. I thought too that it could be a spent fuel rod ejected by the explosion.. does a single rod become heated to a few thousands degrees without cooling?

 

[Borek]

does a single rod become heated to a few thousands degrees without cooling?

If left in open space? Then it cools on itself, radiating and heating air around. Highly doubtful it will get that hot.

 

[KateB]

Kate no offence meant, we should be all kind and loving to each other. Just to illustrate the
enormity of the cooling problem.

Unit 1 is currently generating the heat of 2000 kettles (1000W) boiling away continually and
Unit 2 and 3 about 4000 kettles each, the same tomorrow , the day after slowly getting less
and less and be about a half the amount in 2 month time.

I think I understand what you are saying. The pressure values generated by the extreme energy release would exceed the ability of any set-up using hoses? A good knowledge base of the internal workings of the reactors would be handy ;). I was going off of the pressure and heat values I had seen earlier in the posts, at around (even below) 1 ATMs and temperatures around 150 degrees C and below. (page 64) I had assumed (incorrectly, it appears) that these were values that were within the cooling systems that could be handled by my (now silly) assumption of a rudimentary external heat exchange ... Thanks for your feedback.

 

[M. Bachmeier]

sorry to have brought trouble with my post. I saw the video well before, too, but I hadn't noticed this orange fleck before I read the french thread (which is BTW rather chilling). It may well be just a piece of any orange painted material, but it seems to glow - may be hit by the sun too. I was just interested in knowing your opinion. It is difficult to identify where the shot is located - somewhere around R1 I guess, just after we see the untouched roof of R2 and then R3 and R4. I thought too that it could be a spent fuel rod ejected by the explosion.. does a single rod become heated to a few thousands degrees without cooling?

If your referring to my post suggesting dates, I was not thinking of you. Many new people have joined this discussion which has been a very balanced treatment of the issues so far. I have been following this and other threads and have read every post here. I simply had the fear that the quality of this discussion could drop if posters didn't start monitoring themselves. Dating the information might also ease (unwarranted) fears for those who have family ties in Japan and see this thread as a quality source of information.

 

[AntonL]

If your referring to my post suggesting dates, I was not thinking of you. Many new people have joined this discussion which has been a very balanced treatment of the issues so far. I have been following this and other threads and have read every post here. I simply had the fear that the quality of this discussion could drop if posters didn't start monitoring themselves. Dating the information might also ease (unwarranted) fears for those who have family ties in Japan and see this thread as a quality source of information.

I do agree,

Maybe it is time to ask site administrators to put a sticky "PLEASE READ THIS FIRST" with above plea
especially as search engines now bring this forum into their top pagers

 

[AntonL]

Kyodo news article

http://english.kyodonews.jp/news/2011/03/81133.html"

does not make good reading

However, water is found in the basements of all 4 reactors, if the basement are linked via cable tunnels then it could be a common source of water.

In my opinion this water may come from reactor 2.

My reason is I have investigated past status reports and found that unit 2 has possibly been subjected to too much water injection.
Data extracted sea water injection
18th 35m#/h, 21st 20m3/h, 22nd & 23rd 11m3/h, 23rd & 24th 12m3/h,
fresh water 25th 01:07 20m3/h
and the temperature a constant around 105 degrees C
since temperature readings were reported from 22nd

The required amount of water for latent heat evaporation cooling for unit 2 is 6.3m3/hour as per my calculation

So have Tepco, relying on level and pressure gauges that could be damaged, pumped too much water into Unit 2, leaving no room for steam generation so the water is now being squeezed out and valves or pipe joints are failing and being near 100 degree C no boiling takes place.

sources regarding reactor - http://www.nisa.meti.go.jp/english/files/en20110325-5-3.pdf"

my calculation is based on the attached slide
Po = 2380 MW Thermal (Unit 2 an 3) 1380MW (unit 1)
and assuming 80% station load at time of shutdownList of links to some of the data
http://www.meti.go.jp/press/20110318008/20110318008-4.pdf
http://www.meti.go.jp/press/20110322010/20110322010-3.pdf (first temperature readings)
http://www.nisa.meti.go.jp/english/files/en20110324-2-4.pdf (reactor 4 temperature gauge not working after black smoke)
http://www.nisa.meti.go.jp/english/files/en20110325-5-3.pdf (first fresh water injection)

 

[M. Bachmeier]

I do agree,

Maybe it is time to ask site administrators to put a sticky "PLEASE READ THIS FIRST" with above plea
especially as search engines now bring this forum into their top pagers

It's worse, I found paraphrasing and reproduction of content of this thread, thought I was not recording my search history, so can't point.

This is a terrible thing(nuclear fear) upon a bad thing(big earthquake) upon a terrible x 10 thing(tsunami).

Which means this discussion needs to try to stay as clean as possible. God knows there's enough disinformation and lack of reported facts. This thread has become a valuable source of information and we should try to protect its integrity.

 

[tc2468]

I thought sharing this PDF might better illustrate the functions and structures at Fukushima.

 

[fusefiz]

| http://www3.nhk.or.jp/daily/english/25_10.html
The company says 3.9 million becquerels of radioactive substances per cubic centimeter were detected in the water that the workers were standing in. That is 10,000 times higher than levels of the water inside a nuclear reactor in operation.
The level of radioactive cerium-144 was 2.2 million becquerels. Also, 1.2 million becquerels of iodine-131 was measured. These substances are generated during nuclear fission inside a reactor. (updated at 17:04 UTC, Mar. 25)

 

[Joe Neubarth]

After the explosions I suggested on another forum that if they wanted close up pictures that they could fly a miniature helicopter with a camera on it over the reactor if they really wanted close up clear photos of a site like Reactor Three. Those cameras are available from the US military and well as other sources.

The fact that they have not done so tells me that they do not want to. They could see the spent fuel rod tank without having to risk a single person's life.

For that matter, instead of having firemen standing and tending their hoses, they could have put a hose on a hook that was positioned by helicopter (a big one this time) that could have directed a stream of water on the reactor compartment or the fuel rod pool. I have not seen that done. Instead we saw photos of men standing out in the open holding hoses. Not too bright.

 

[athegreat]

After the explosions I suggested on another forum that if they wanted close up pictures that they could fly a miniature helicopter with a camera on it over the reactor if they really wanted close up clear photos of a site like Reactor Three. Those cameras are available from the US military and well as other sources.

The fact that they have not done so tells me that they do not want to. They could see the spent fuel rod tank without having to risk a single person's life.

For that matter, instead of having firemen standing and tending their hoses, they could have put a hose on a hook that was positioned by helicopter (a big one this time) that could have directed a stream of water on the reactor compartment or the fuel rod pool. I have not seen that done. Instead we saw photos of men standing out in the open holding hoses. Not too bright.

Just because they haven't released photos doesn't mean they haven't taken them. And I think they probably know more about cooling a reactor than you do. For instance, radiation levels were pretty high at one point in the air over the plant so maybe a helicopter could not stay there very long.

 

[KateB]

| http://www3.nhk.or.jp/daily/english/25_10.html
The company says 3.9 million becquerels of radioactive substances per cubic centimeter were detected in the water that the workers were standing in. That is 10,000 times higher than levels of the water inside a nuclear reactor in operation.
The level of radioactive cerium-144 was 2.2 million becquerels. Also, 1.2 million becquerels of iodine-131 was measured. These substances are generated during nuclear fission inside a reactor. (updated at 17:04 UTC, Mar. 25)

Implications? Is water cooling still an option in this scenario? I would think with the explosivity of extreme temps and water, as well as the much higher and more dangerous particles possibly contaminating ground water for miles, that an alternative, assuming there is one, needs to be assessed. IS there an alternative? What about cooling the exterior areas with LN2, without coming into contact with RCV? Too hot still?
Edit: what about LN2, Solid N2 slurry?

 

[fusefiz]

| http://www.nytimes.com/2011/03/26/world/asia/26japan.html?_r=3&hp=&pagewanted=all

A senior nuclear executive who insisted on anonymity but has broad contacts in Japan said that there was a long vertical crack running down the side of the reactor vessel itself. The crack runs down below the water level in the reactor and has been leaking fluids and gases, he said.

The severity of the radiation burns to the injured workers are consistent with contamination by water that had been in contact with damaged fuel rods, the executive said.

“There is a definite, definite crack in the vessel — it’s up and down and it’s large,” he said. “The problem with cracks is they do not get smaller.”

But Michael Friedlander, a former nuclear power plant operator in the United States, said that the presence of radioactive cobalt and molybdenum in water samples taken from the basement of the turbine building raised the possibility of a very different leak.

Both materials typically occur not because of fission but because of routine corrosion in a reactor and its associated piping over the course of many years of use, he said.

The aggressive use of saltwater to cool the reactor and its storage pool for spent fuel may mean that more of these highly radioactive corrosion materials will be dislodged and contaminate the area in the days to come, posing further hazards to repair workers, Mr. Friedlander added. Whichever explanation is accurate, the contamination of the water in the basement of the turbine building poses a real challenge for efforts to bring crucial cooling pumps and other equipment back online.

“They can’t even figure out how to get that out, it’s so hot” in terms of radioactivity, the senior nuclear executive said.

(Published: March 25, 2011)

 

[AntonL]

It's worse, I found paraphrasing and reproduction of content of this thread, thought I was not recording my search history, so can't point.

This is a terrible thing(nuclear fear) upon a bad thing(big earthquake) upon a terrible x 10 thing(tsunami).

Which means this discussion needs to try to stay as clean as possible. God knows there's enough disinformation and lack of reported facts. This thread has become a valuable source of information and we should try to protect its integrity.

Agree - maybe an administrator should do some censoring and delete inappropriate posts - should be seriously considered

 

[tyroman]

@TCups

I have read every post in this thread and have seen no reply to your "Primary Containment explosion" theory which addresses the following:

There is no question in my mind that Hydrogen escaping from the SFP's (or by some path out of the reactor core) could (and did) explode once it mixed with relatively dry air above the SPFs. However, I believe there would be insufficient Oxygen available within the Primary Containment for a Hydrogen explosion to occur there for the following reasons.

Consider the reaction which produces the Hydrogen;

Zr + 2 H2O = ZrO2 + 2 H2

In this reaction, all of the Oxygen in a water molecule is "fixed" on the surface of the fuel cladding in the form of zirconium oxide.

When Hydrogen burns (explodes), there is one molecule of Oxygen for each molecule of Hydrogen;

2 H2 + O2 ---> 2 H2O

The only other source for Oxygen within the RPV / Primary Containment might be the release of air entrained or dissolved in the cooling seawater or Oxygen released directly from the core via radiolysis of the surrounding water/steam.

The radiolysis source is questionable since it occurs at twice the temp of a redox reaction (between water and zirconium) and the heat source in the core is decay heat not fission generated.

The seawater source is more problematic...

Flamable/explosive gases such as Hydrogen have something called UEL or Upper Explosive Limit.

See;
[http://en.wikipedia.org/wiki/Flammability_limit]

"Upper Explosive Limit (UEL): Highest concentration (percentage) of a gas or a vapor in air capable of producing a flash of fire in presence of an ignition source (arc, flame, heat). Concentrations higher than UEL are "too rich" to burn."

From the table at the same link, Hydrogen's UEL in % by volume of air is 75%. Air is composed of about 21% by volume Oxygen. I expect that these figures are at STP for dry air and would need to be adjusted for the temperature and pressure in the Primary Containment. Additionally, the presence of steam in the same space as the Hydrogen and Oxygen inhibits their reaction. Thus, when the Hydrogen mixes with relatively dry air above the SPFs it can explode... but perhaps not while it is within the steamy Primary Containment.

Maybe one of our Nuclear Engineers can address your theory from this perspective.

.

 

[Reno Deano]

More than likely TEPCOs saltwater injection was via the reactor feed system which begins in the Turbine Bldg. There may have been a back flow at some time (on 2-3 inches of water) during the set up and change over. If they created a direct patch to either the Reactor Vessel or the Dry Well, then they also created a return path from those points. Just a plumber's theory.

 

[jensjakob]

Background reading: The Chernobyl Record - background, radiation theory, facts:
http://www.scribd.com/doc/40414231/Chernobyl-Record

 

[Joe Neubarth]

We see hundreds of people on this forum trying to put together the pieces of the puzzle that are the bits of the information that have been released. It is a shame that in this crisis they are not being more transparent.

 

[|Fred]

On the 25th at 03:13AM JST there was a press conference open to the international press as it was translated in English, Unfortunately very few reporter were there, and the stream that I was watching cut off after 6 minutes.. (too boring for the cameraman I guess -_- )

None the less I toke a few screen grab, the topic was the design of the BWR used in fukushima , specification , and way of predicted leaking of the RCV under pressure.

Shame they did not record the full conference, we might have glance a few more informations

The BWR Mark 1 made by GE used in Fukushima is the enhanced one with a bigger drywell (on the right)
[PLAIN]http://k.min.us/ijHsci.jpg
Design spec
Leakage ref to the containment vessel
[PLAIN]http://k.min.us/ijLcum.jpg
Bolted top with flange allowing leakage
[PLAIN]http://k.min.us/ijLGOE.jpg
[PLAIN]http://k.min.us/ijGD7G.jpg

 

[Astronuc]

| http://www.nytimes.com/2011/03/26/world/asia/26japan.html?_r=3&hp=&pagewanted=all

A senior nuclear executive who insisted on anonymity but has broad contacts in Japan said that there was a long vertical crack running down the side of the reactor vessel itself. The crack runs down below the water level in the reactor and has been leaking fluids and gases, he said.

The severity of the radiation burns to the injured workers are consistent with contamination by water that had been in contact with damaged fuel rods, the executive said.

“There is a definite, definite crack in the vessel — it’s up and down and it’s large,” he said. “The problem with cracks is they do not get smaller.”

But Michael Friedlander, a former nuclear power plant operator in the United States, said that the presence of radioactive cobalt and molybdenum in water samples taken from the basement of the turbine building raised the possibility of a very different leak.

Both materials typically occur not because of fission but because of routine corrosion in a reactor and its associated piping over the course of many years of use, he said.

The aggressive use of saltwater to cool the reactor and its storage pool for spent fuel may mean that more of these highly radioactive corrosion materials will be dislodged and contaminate the area in the days to come, posing further hazards to repair workers, Mr. Friedlander added. Whichever explanation is accurate, the contamination of the water in the basement of the turbine building poses a real challenge for efforts to bring crucial cooling pumps and other equipment back online.

“They can’t even figure out how to get that out, it’s so hot” in terms of radioactivity, the senior nuclear executive said.

(Published: March 25, 2011)

Ouch! Crack(s) in the RPV is a problem. At this point though, the drywell should be flooded to the extent possible.

Co and Mo (and Tc-99) would come from activated corrosion products, which is normal. Usually, these products are filtered from the water (condensate polishers), or they deposit on the fuel. This does not indicate fuel failure (cladding breach).

The release of Xe, Kr, Cs, I, . . . isotopes would be expected from failed fuel rods, but that could mean small or tight leaks. These elements are gaseous or volatile, so they readily come out of failed fuel.

The indication of Ce-144 is a more serious indication of breached fuel. If Np-239 was measured in the water, that too would indicate fuel washout.

I also just realized that the cladding is probably liner (barrier) cladding, and it's possible that breached cladding could split open through reaction (oxidation of the liner) with the coolant, especially if the cladding temperature approached operational temperatures. I'm not sure that anyone has done an experiment on BWR fuel degradation in seawater, so this is likely uncharted territory.

 

[|Fred]

here are the result of the water analysis found in the basement of the Turbine unit 1 ( source nisa)

[PLAIN]http://k.min.us/imbXPu.jpg

 

[jensjakob]

"Drywell head is predicted to unseat at 27 psig" (page 5, upper part)
http://www.osti.gov/bridge/purl.cov...F5E975EF06A9A903D0D15E6?purl=/5630475-EX87x5/

"Just a few square inches are enough to relieve pressure"
"Due to the large surface of the drywell head, leaks are easy"

If that is true - then there is a SERIOUS flaw in the BWR 1 (and otherrrs?) design - and a quite plausible documentation for TCups theory.


Found also this detail diagram of drywell head fastening:
http://www.ansn.org/Documents/Training/PSA%20Level%202%20(Probabilistic%20Safety%20Assessment)/M5%20%20Containment%20Perform.ppt#292,17,Example: BWR Drywell Head Seal

 

[Joe Neubarth]

Ouch! Crack(s) in the RPV is a problem. ...

I also just realized that the cladding is probably liner (barrier) cladding, and it's possible that breached cladding could split open through reaction (oxidation of the liner) with the coolant, especially if the cladding temperature approached operational temperatures. I'm not sure that anyone has done an experiment on BWR fuel degradation in seawater, so this is likely uncharted territory.

Just like there were lots of examples of past accidents included in my reactor training days, there will be lot of learnings garnered from what has happened in Japan. Doctorates will be written on those learnings.

 

[timeasterday]

On the 25th at 03:13AM JST
The BWR Mark 1 made by GE used in Fukushima is the enhanced one with a bigger drywell (on the right)
[PLAIN]http://k.min.us/ijHsci.jpg

The shape on the right reminds me of an earlier photo showing a round hole atop some "whiskey distillery" shaped object.

 

[PietKuip]

here are the result of the water analysis found in the basement of the Turbine unit 1 ( source nisa)

[PLAIN]http://k.min.us/imbXPu.jpg[/QUOTE]

Chlorine-38 has a 37 minutes half-life- Where could it come from? Neutron activation of the brine??

 

[KateB]

Chlorine-38 has a 37 minutes half-life- Where could it come from? Neutron activation of the brine??

Looks like it is common in BWR's, and that you are correct, NaCl impurities in water.

http://www.nap.edu/openbook.php?record_id=9263&page=116

 

[M. Bachmeier]

Looks like it is common in BWR's, and that you are correct, NaCl impurities in water.

http://www.nap.edu/openbook.php?record_id=9263&page=116

Kate are we looking at unlikely chemistry. This case is unprecedented, with ocean water and uncounted types of impurities potentially interacting with isotopes?