Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[GJBRKS]

Mechanical seals are used between the reactor pressure vessel and the containment structure (labeled "RPV to Drywell Bellows Seal" in
Figure 8-1) and between the drywell and the refueling cavity (labelled "Drywell
to Reactor Building Bellows" in Figure 8-1 ...

page 113

http://www.ucsusa.org/assets/documents/nuclear_power/nuclear-waste-disposal-crisis-excerpts.pdf

http://img856.imageshack.us/img856/5109/rpvseals.th.png

 

[Rive]

what are we observing here? looks like racks in a spent fuel pool but of which unit? and what is the significance of the brown rods, yellow finger is waving up and down along this brown object in video, could this be an oxidized fuel casing?
[PLAIN]http://k.min.us/ikRUO0.JPG[/QUOTE]
The packbot is looking upward, to some catwalk or cable-tray. Maybe it's the place where the cables penetrates the containment - the view is familiar from one of the older packbot-videos.

Ps.: 3:05 - 3:15

 

[SteveElbows]

Those recurring conspiracy theories are getting a bit old... If you want to argue please do so with evidence and not based on assumption.

...

I only checked the two first days.. hardly enough to conclude anything that may have accrued after..Again I don't mind you finding evidence of wrong doing.

And Again please check http://www.nsc.go.jp/mext_speedi/0312-0424_in.pdf What the hell
Children thyroid potential intake dosed above 100mSv this area, with 3 or 4 towns! outside the evac... That's something to be pissed at

Perhaps we are arguing when we are in fact agreeing. My presumption is that many criticisms of the evacuation are to do with areas north west. People are generally not complaining that the initial evacuations were not done quickly enough, they are complaining that the areas of evacuation were not updated promptly once actual data became available to the authorities (& other like Greenpeace) that some of these areas to the north west would need to be evacuated. And when the government finally announced this stuff, they gave people a very long time to leave these areas, and got in further trouble over this issue of child safety & school playground topsoil removal, the resignation of the expert, etc.

Anyway, continuing my dredging up of old news on the evacuation and how it was handled, here we see two March 23rd articles where it is very clear that the government knows the reality of the contamination to the north west, but are not giving people full details or movin swiftly to change the evacuation zone:

Japan's science ministry says relatively high radiation levels have been detected on 2 consecutive days about 30 kilometers northwest of the quake-damaged Fukushima Daiichi nuclear power plant.

The radiation measured 170 microsieverts per hour on Thursday and 150 microsieverts on Friday.

Chief Cabinet Secretary Yukio Edano says the government will take appropriate measures if this level of contamination continues in the area for a long period. But he says this would be unlikely.

Radiation was measured for 2 hours from 10AM on Friday at 18 spots in areas 30 to 60 kilometers from the plant in Fukushima Prefecture.

The highest reading of 150 microsieverts per hour was detected at around 1:30 PM local time, about 30 kilometers northwest of the plant. The location is within the zone where residents have been instructed to stay indoors.

Readings of 170 microsieverts were recorded at the same location at 2 PM on the previous day, Thursday.

Experts say exposure to this amount of radiation for 6 to 7 hours would result in absorption of the maximum level considered safe for one year.

The ministry also observed radiation levels of 0.5 to 52 microsieverts per hour at other observation points within a 30 to 60 kilometer radius of the plant. It says these levels are all higher than normal, but not an immediate threat to health.

The government has evacuated residents living within a 20 kilometer radius of the plant, and instructed those in a 20 to 30 kilometer radius to stay indoors.

Extremely high radiation found in soil
Japanese authorities have detected a concentration of a radioactive substance 1,600 times higher than normal in soil at a village, 40 kilometers away from the troubled nuclear power plant in Fukushima Prefecture.

The disaster task force in Fukushima composed of the central and local governments surveyed radioactive substances in soil about 5 centimeters below the surface at 6 locations around the plant from last Friday through Tuesday.

The results announced on Wednesday show that 163,000 becquerels of radioactive cesium-137 per kilogram of soil has been detected in Iitate Village, about 40 kilometers northwest of the plant.

Gakushuin University Professor Yasuyuki Muramatsu, an expert on radiation in the environment, says that normal levels of radioactive cesium-137 in soil are around 100 becquerels at most. The professor says he was surprised at the extremely high reading, which is 1,630 times higher than normal levels.

He warns that since radioactive cesium remains in the environment for about 30 years it could affect agricultural products for a long time. He is calling on the government to collect detailed data and come up with ways to deal with the situation.

The map on page 4 of the following presentation dated March 22nd, gave me enough data that when combined with all the previous stories I posted, an evacuation of some parts beyond the evacuation zone, to the north-west of the plant, seemed like a no-brainer.

http://www.slideshare.net/energy/radiation-monitoring-data-from-fukushima-area-march-22-2011

But what actually happened next? Mostly a week of silence on this subject in the press, until March 30th when Greenpeace measured radiation levels in some areas and publicly stated that Iitate was a concern, and urged the Japanese government to at least evacuate pregnant women and children from some of these places. Also on about March 30th IAEA also said much the same thing:

http://allthingsnuclear.org/post/4213197648/iaea-confirms-very-high-levels-of-contamination-far

This got quite a bit more attention in the press. But still nothing much happened. Then around April 4th, the first coverup of SPEEDI data was talked about by NHK world:

It has been learned that the Japanese government withheld the release of computer projections indicating high levels of radioactivity in areas more than 30 kilometers from the troubled Fukushima Daiichi nuclear power plant.

The estimates were made on March 16th following explosions at the plant by an institute commissioned by the government using a computer system called SPEEDI. The system made its projections on the assumption that radioactive substances had been released for 24 hours from midnight on March 14th, based on the available data.

But the government was reluctant to reveal the SPEEDI projections, and did not release them until March 23rd.
The released data showed that higher levels of radioactive substances would flow over areas to the northwest and southwest of the plant.

The estimates showed that the radiation would exceed 100 millisieverts in some areas more than 30 kilometers from the nuclear plant if people remained outdoors for 24 hours between March 12th and 24th.

That is 100 times higher than the 1 millisievert-per-year long-term reference level for humans as recommended by the International Commission on Radiological Protection.

The Nuclear Safety Commission says it did not release the projections because the location or the amount of radioactive leakage was not specified at the time.

Professor emeritus Shigenobu Nagataki of Nagasaki University, says the government should release more data about the dangers of possible radiation exposure and draw up evacuation plans and other measures together with residents.

Monday, April 04, 2011 12:38 +0900 (JST)

Thats the end of part 2 of my evacuation recap.

 

[SteveElbows]

Here is the final part of my rough guide to the evacuation.

On April 6th, after weeks of bad sounding news and data about some locations, there was finally some fresh action taken, although it sounds more like a local government initiative than a national one, as detailed in another NHK world story:

Pregnant women and small children in IItate village in Fukushima Prefecture, about 40 kilometers from the crippled Fukushima Daiichi nuclear plant, will be temporarily evacuated if they apply to do so.

The decision by the prefecture and village on Wednesday came as concerns mount among residents
over high radiation levels detected in the village.

Iitate is located outside the evacuation zone for the troubled nuclear plant. But the village's radiation level recorded nearly 45 microsievert per hour at its peak on March 15th, and has been significantly higher than most other areas more than 30 kilometers away from the plant.

On Wednesday, the level is about 6 microsieverts per hour, but even this would exceed 1,000 microsieverts if people remained outdoors for 24 hours over about one week. 1,000 microsieverts-per-year of radiation is the long-term reference level for people as recommended by the International Commission on Radiological Protection.

The village says it will arrange evacuation to Fukushima City for about 2 months, and those eligible to apply will be pregnant women, children younger than 3 and their guardians.

The village will start evacuating them in a week's time.
Wednesday, April 06, 2011 13:31 +0900 (JST)

And then, finally, on April 11th the government acted:

http://english.kyodonews.jp/news/2011/04/84604.html

The government will expand evacuation districts near the crippled Fukushima Daiichi nuclear power plant, its top spokesman said Monday.

With the crisis at the plant dragging on, some municipalities within a 20- to 30-kilometer radius of the power plant will now be designated as additional evacuation areas, Chief Cabinet Secretary Yukio Edano said at a news conference.

Previously, the government said that outside radiation levels of over 50 millisieverts require evacuation, and advises residents to remain indoors when levels exceed 10 millisieverts.

From now on, it will issue an evacuation order if there is a possibility of residents receiving a dose of 20 millisieverts during the course of a year.

In the event of an emergency, the International Commission on Radiological Protection is recommending also that the highest planned residual dose over one year be in the range of 20 to 100 millisieverts.

The municipalities which will be part of the new evacuation zone include Katsurao, Namie and Iitate, all located in Fukushima Prefecture.

Residents in these municipalities will be expected to move to different areas within one month, Edano said.

I have some sympathy with the authorities because they had a lot to deal with from earthquake & tsunami damage, but as my recent posts show I think its hard to see why this stuff dragged on into April, and seeing as the evacuation order was not immediate, into May as well. Have we heard any recent news about how the evacuation of these areas is going, as they don't have much more than a week left before a month has passed since the decision to evacuate these towns? The only news I've heard of evacuations really was the changing of law to prevent people going back within the original evacuation area, and a bit of fiddling with the rules to enable people to return briefly to retrieve valuables.

 

[razzz]

Unit 1 is another balancing act even if they can flood to cover all the fuel, the heat being generated along with any gases allows a pressure build up so cooling the source of the heat minimizes the pressure being created causing ambient air. This means Unit 1 is has a leak but not as bad as 2&3 nonetheless problematic whereas do you cool the fuel remaining above water level via steam or allow fuel to meltdown to water level?

Either way, eventually, ending up with ambient air but taking a longer amount of time for a cool down for Unit 1 with a large amount of accumulating contaminated water.

Even if they plug the leak, they need a closed loop for proper cooling.

 

[MadderDoc]

<..>
But if this 'spanner' is in place then the much heavier FHM should be there somewhere too.

If that is to be inside the confines of the north end of the building, the machine has likely been ballistic and would be expected to be considerably damaged. The building too, would be considerably damaged at the area of impact. The area would be expected to contain green wreckage of a particular tint. Pointed to in the attachment would seem to be the most, if not the only likely fit.

 

[Bandit127]

Data...

Collection, validation and then testing against hypotheses. The result of those tests allow us to draw valid conclusions from the data and make sound decisions based on it.

If the data we gather fails the validation, we change the way we gather it or we gather more. (For example, validation of data for drugs approval involves billions of dollars, many thousands of data points and provides sufficient confidence in it that all parties can agree on the conclusions made. I we diverge on those conclusions over time (as happens), then we did not gather sufficient valid data in the first place).

The problem we all have - from TEPCO, to the general public, is that we do not have enough data to draw valid conclusions.

Therefore, people in Japan can discriminate against refugees from Fukushima. TEPCO can refuse to release data that they have no confidence in (I salute them for that). And pixel peepers on this forum can make up all sorts of stories about green boxes outside Unit 4. Or 6 posters can postulate on a 40 deg increase in a temperature reading from a system that has been wrecked. (If I tried to validate an Autoclave with the thermocouples in Units 1-4 I would probably lose my job).

We are all desperate for answers - ultimately 'the truth' - but that data will not be available for many years.

In the meantime we simply don't have the data to draw conclusions from. Our only saviour are qualifications and experience. The experts are qualified and experienced in the processes and systems that are going on (NUCENG, ASTRONUC are immediate examples, there are others in the same league). Most of the rest of us are not.

This means that they are qualified to draw conclusions on smaller sets of data than the rest of us. And small sets of data are all that we have right now.

So, listen to the experts and add weight to their conclusions. They are more likely to be right than the others here that post their views with less care and authority. And understand that they may give an answer that means no conclusion can be drawn, because the data is simply not valid.

And spare a thought for the TEPCO Engineers that are trying to control (probably) the worst nuclear accident we have faced with perhaps 1% of the data they need to do the job right.

A last point (and thanks for listening). Probably the one of the best qualified people to draw conclusions (and that will be based on undoubtedly the most amount of data) of anybody I have read on this is here:

http://www.gengikyo.jp/english/shokai/Tohoku_Jishin/article_20110413.htm

 

[fluutekies]

Lots of pre-quake images here: http://www.houseoffoust.com/fukushima/phototour.html

 

[triumph61]

page 113

http://www.ucsusa.org/assets/documents/nuclear_power/nuclear-waste-disposal-crisis-excerpts.pdf

http://img856.imageshack.us/img856/5109/rpvseals.th.png

Here is another Damage- Unit 3

 

[ascot317]

Lots of pre-quake images here: http://www.houseoffoust.com/fukushima/phototour.html

"1939 - Tokyo Electric Power Plan to build Fukushima"

Wow, that's one year after the discovery of fission and more than three years before CP-1.

Nevertheless, very very nice collection of pictures.

 

[turi]

Indeed, water level in the #1 reactor has been 1.6 meters below the top of the fuel for some 40 days now. It is even lower in reactors #2 and #3.

You're sure about reading those numbers as below the fuel? In the press releases it only says "Distance from the top of the fuel" but not which direction. Initially I've been a bit confused about the negative numbers. Then about two weeks ago I was able to correlate the readings with some other statements from tepco with the same data which made it clear (to me at least) that a negative reading meant above the fuel. Does anyone have a source to verify?

 

[elektrownik]

You're sure about reading those numbers as below the fuel? In the press releases it only says "Distance from the top of the fuel" but not which direction. Initially I've been a bit confused about the negative numbers. Then about two weeks ago I was able to correlate the readings with some other statements from tepco with the same data which made it clear (to me at least) that a negative reading meant above the fuel. Does anyone have a source to verify?

100% that "-" mean that it is below top of fuel sets.

 

[GJBRKS]

You're sure about reading those numbers as below the fuel? In the press releases it only says "Distance from the top of the fuel" but not which direction. Initially I've been a bit confused about the negative numbers. Then about two weeks ago I was able to correlate the readings with some other statements from tepco with the same data which made it clear (to me at least) that a negative reading meant above the fuel. Does anyone have a source to verify?

From the timed data it's easy to see that these readings were positively numbered before the explosions : http://www.gyldengrisgaard.dk/fukmon/uni2_monitor.html

I don't think there is any fuel left above the waterline , it all melted and dropped .

That's how they they can estimate the percentages of core damage

 

[elektrownik]

A lot of steam/smoke on tepco web cam, I didnt saw so much science many days...

 

[clancy688]

That's how they they can estimate the percentages of core damage

We had that discussion about core damage maybe a week or so before.

Core damage is estimated by drywell and wetwell radiation, they're recalculating how much of the core's inventory is outside the zircalloy shielding based on these numbers.

See here: https://www.physicsforums.com/showpost.php?p=3271215&postcount=5187

The only information these estimates provides us is "there's x% of the core inventories inside the RPV". It doesn't say anything about meltdowns.
It's also possibly that nothing has molten, but the zircalloy ruptured and great parts of the fuel rod's fission products were simply washed out.

 

[GJBRKS]

We had that discussion about core damage maybe a week or so before.

Core damage is estimated by drywell and wetwell radiation, they're recalculating how much of the core's inventory is outside the zircalloy shielding based on these numbers.

See here: https://www.physicsforums.com/showpost.php?p=3271215&postcount=5187

The only information these estimates provides us is "there's x% of the core inventories inside the RPV". It doesn't say anything about meltdowns.
It's also possibly that nothing has molten, but the zircalloy ruptured and great parts of the fuel rod's fission products were simply washed out.

Oke , perhaps not molten , maybe broken

But it 100% cannot be above the waterline , so all former fuel % above the current waterline is damage %

 

[default.user]

The only information these estimates provides us is "there's x% of the core inventories inside the RPV". It doesn't say anything about meltdowns.
It's also possibly that nothing has molten, but the zircalloy ruptured and great parts of the fuel rod's fission products were simply washed out.

We had the development of hydrogen gas. This is only possible if zirconium is delivered at a temperature of at least 800 degrees Celsius.

It is fair to speak of a molten core.

Let us not always start from point zero. the facts are proved scientifically.

Uranium pellets have a higher melting point. That's right. It says nothing about a possible criticality of the corium.

We have, therefore possibly increasing or constant temperatures in the reactor cores.

We have corium, whose whereabouts is not clear.

We have no values ​​of deuterium, americium or cobalt. All these data would be needed for a reliable analysis of the situation on the ground.

wrote with google-translator

Kind regards from germany

 

[jpquantin]

As I have learned the "skimmer level" is not the water level in the SFP
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110418e5.pdf"

The temperature is rising since the last days, but is still lower than the highest readings in the past. So maybe it does not explode by now ;)

Yes skimmer surge tank and SFP communicate through their upper part, and FPC skimmer level does not give SFP level. However, it gives an indication on the moments the SFP is full, and whether a water injection or spray fills in the pool or not.

If FPC skimmer level increases, it means water has overflowed from the SFP, and thus that the SFP was full during the previous water injection / spray.

Amount of water added between two "SFP full" signals gives an estimate of the amount of its losses between those two signals.

Second indication is given when dealing with temperature. The only reported SFP temperature is that of SFP2. Temperature increases with skimmer level. Temperature of the SFP seems to be measured in the FPC skimmer. When SFP overflows, water coming from it flows in FPC skimmer, mixing with water already there. One could deduce temperature in SFP, when we have temperature and level before and after overflow.

Now what does it tell us for the various SFP ?

SFP1: skimmer level has never raised, even when Tepco performed the (only reported) refill on Mar 31st (90 tons). We have no proof by this measurement that SFP1 has enough water. We can wonder how Tepco follows SFP1 (absence of steam above SFP1 ?).

SFP2: we have 9 signals showing that SFP was full (between brackets the tons of water required to get "full" signal again, followed by the caculated loss rate [tons per day])
- 01/04/2011 17:05
- 04/04/2011 13:37 (70 => 24.5)
- 10/04/2011 12:38 (96 => 16.1)
- 13/04/2011 14:55 (60 => 19.3)
- 16/04/2011 11:54 (45 => 15.6)
- 19/04/2011 17:28 (47 => 14.5)
- 22/04/2011 17:40 (50 => 16.6)
- 25/04/2011 11:18 (38 => 13.9)
- 28/04/2011 11:28 (43 => 14.3)

SFP2 seems basically quite full all the time. Its max loss in this period is 96 tons, which is roughly only 6% of it. SFP2 level seems under control. What about temperature ? For example, for the last "full" event (28/04/2011 11:28), level before overflow was 5400 (millimiters in skimmer) and temp was 50°C. After it, was 6000 and 71. What was the temperature of the added Water, assuming FPC skimmer is of cylinder form ? Well FPC skimmer 2 has leaks, which are about 400 millimeters per day.

So at the exact end of injection, level could have been 6400. Well my own calculation shows water temperature above boiling point ... Any clue to calculate this ? Any info on FPC skimmer form and dimensions ?

SFP3: we have no report of FPC skimmer level. The only information is that they have added at least 1000 tons of water to it since beg. of earthquake. For SFP3 also we can wonder how they monitor the level of it (and temperature).

SFP4: we have only 4 signals (same reporting than SFP2):
- 13/04/2011 06:57 (prior to this: about 1550 tons injected / sprayed)
- 15/04/2011 18:29 (140 => 56.4)
- 17/04/2011 21:22 (140 => 66)
- 27/04/2011 14:44 (1210 => 124)

SFP4 has important losses. Simply by boiling, SFP4 would lose max 71 tons per day. The last figure tells us that SFP4 leaks, and is capable to leak importantly (53 tons per day in some circonstances). One important fact is that losses became accelerating since Apr. 17th. The most problematic is that I do not see any refill since the 27/04/2011 14:44; extrapolating this could mean SFP4 has left about 570 tons since then, roughly 1/3 of its height (assuming gate is still there ...). When was the video showing SPF4 underwater was taken ?

 

[hbjon]

We had that discussion about core damage maybe a week or so before.

Core damage is estimated by drywell and wetwell radiation, they're recalculating how much of the core's inventory is outside the zircalloy shielding based on these numbers.

See here: https://www.physicsforums.com/showpost.php?p=3271215&postcount=5187

The only information these estimates provides us is "there's x% of the core inventories inside the RPV". It doesn't say anything about meltdowns.
It's also possibly that nothing has molten, but the zircalloy ruptured and great parts of the fuel rod's fission products were simply washed out.

The reason gold can be panned is because it is heavier than water and all the other material that is is suspended in. I can't see U235 or U238 washing too far away. And why is it some users can get away with putting up nonsense and I get threatened within an inch of my life? Kind regards from Minnesota.

 

[elektrownik]

There is something wrong, I never saw so much steam/smoke on tepco web cam science tsunami, It looks very bad...
http://www.tepco.co.jp/nu/f1-np/camera/index-j.html

 

[SteveElbows]

When was the video showing SPF4 underwater was taken ?

April 28th according to TEPCO.

Thanks very much for the quality thoughts on the fuel pools. Earlier on I had been taking the published readings as direct indications of pool height, and it was only when I looked at the trends over time that the real story of the skimmer surge tanks & their relationship to the pool started to dawn on me. So your post was very helpful and saved me lots of work.

I will probably still try to keep somewhat of an open mind about this data and what it means, just in case there is some factor we are missing, or for example if they have already tried to convert the raw skimmer water temperature into a pool temperature before publishing the data. I doubt this but its just one example of things I cannot be sure about.

Certainly I believe they have some other data available to them that does not get published very often, but I've no way to know how often they get this data themselves and choose not to publish. For example I believe they have mentioned the unit 4 pool temperature being at 91 degrees C at some point, perhaps just before they went on the massive spraying binge that finally ended on the 27th. I assume they used a sensor hanging from the pumping crane, but detail or regular updates on these temperatures are not often to be found. Perhaps they really arent measuring it more often than we get to hear about, but if I were them I would want as much data as possible.

 

[Borek]

There is something wrong, I never saw so much steam/smoke on tepco web cam science tsunami, It looks very bad...
http://www.tepco.co.jp/nu/f1-np/camera/index-j.html

Have you checked temperature at the place?

 

[bytepirate]

There is something wrong, I never saw so much steam/smoke on tepco web cam science tsunami, It looks very bad...
http://www.tepco.co.jp/nu/f1-np/camera/index-j.html

i happen to live near a 'cloud factory' (that's how my children call it, we would say cooling tower ;-))
the amount of steam seen varies a lot with weather conditions (btw even the colour does, sometimes it looks like smoke from some angles, when it's certainly only steam).

i would not worry to much.

EDIT:

Have you checked temperature at the place?

almost the same as here, i am tempted to take a walk to compare with my cloud factory ;-)

http://www.weather.com/weather/today/Fukushima+Japan+JAXX0010 (i know, fukushima city is way from the plant. should not make a big difference though)

 

[triumph61]

SFP4: we have only 4 signals (same reporting than SFP2):
- 13/04/2011 06:57 (prior to this: about 1550 tons injected / sprayed)
- 15/04/2011 18:29 (140 => 56.4)
- 17/04/2011 21:22 (140 => 66)
- 27/04/2011 14:44 (1210 => 124)

SFP4 has important losses. Simply by boiling, SFP4 would lose max 71 tons per day. The last figure tells us that SFP4 leaks, and is capable to leak importantly (53 tons per day in some circonstances). One important fact is that losses became accelerating since Apr. 17th. The most problematic is that I do not see any refill since the 27/04/2011 14:44; extrapolating this could mean SFP4 has left about 570 tons since then, roughly 1/3 of its height (assuming gate is still there ...). When was the video showing SPF4 underwater was taken ?

There are Water Level Data.
The Level rises at27. (last time spraying)4250mm suddely to 28. 6550mm. Today the Level is 5550mm.
At 27. Tepco said the Pool is leaking. At 28. Tepco said the Pool is NOT leaking. Whats happend? Did they find the leaked? Perhaps they also restore the cooling?

 

[MadderDoc]

<..>I see no evidence that this heat-damage what we are talking about is in connection with the fire/blast.<..>

I am sure you have noticed that a part of the metal roof structure is missing on the roof in the south end. That's because in the course of the blast it ended up in the yard between units 3 and 4. Fortunately its attachment to the south edge of the roof has been that much retained that one can see that one end has been torn apart, while the other end appears to have been affected by a similar heat-damage what we are talking about effect. Are we to assume three separate fire/blast events, two on the roof and one in the yard?

Detail from one end of the roof structure landed in the 3/4 yard:

 

[MiceAndMen]

"1939 - Tokyo Electric Power Plan to build Fukushima"

Wow, that's one year after the discovery of fission and more than three years before CP-1.

Nevertheless, very very nice collection of pictures.

That was my reaction as well. houseoffoust has managed to collect a few items of interest but the presentation and analysis is frequently amateurish.

 

[~kujala~]

Simply by boiling, SFP4 would lose max 71 tons per day.

Sorry if this has been discussed earlier.

France's IRSN has calculated that SFP 4 would lose max 115 tons per day.

Unit 4 pond contains a total 1331 used assemblies (783 plus full fuel load of 548), giving it a heat load of about 3 MW thermal, according to France's IRSN, which in that case could lead to 115 cubic metres of water boiling off per day, or about one tenth of its volume.

http://www.world-nuclear.org/info/fukushima_accident_inf129.html

MIT has calculated that even after 1 year the decay heat for units 2 & 3 after scram would be 5 MW per unit. Units 2 & 3 contain the same amount of reactor fuel assemblies that SFP 4 has spent/partially fuel assemblies (4 months old).
http://mitnse.com/2011/03/16/what-is-decay-heat/

(MIT is stating that their calculation is conservative, though.)

How was this 71 tons calculated? And can we be absolutely sure about it?

 

[jlduh]

To Steveelbows: thanks for the quite exhaustive summary of the evacuation decision versus released contamination data sequences, most of the articles you list have been posted or discussed here in early pages of this thread (i remember reading most of them...), but this is important at some point to assemble individual images to build the "film" of the events. I remember very well the fact that in many statements, there was this dichotomy: alarming results in some areas (North west mainly) BUT no worry, no immediate health risk and so on (i wrote one post on this special dialectic). Your demonstration is pretty self explanatory of what some other members were trying to enlighthen...

To Fluuketies: very interesting photos, very very interesting really. They must have been posted by a Tepco employee, don't you think? Surprised to see so many pictures of cracks in the shroud core and lost objects in places where they shouldn't be (SFP, torus, well, etc.)

To GJBRKS; the document you posted from Lochenbaum

http://www.ucsusa.org/assets/documen...s-excerpts.pdf

is also VERY INFORMATIVE on SFP's failure modes from safety stand point! I'm currently reading it and you can learn a lot about these SFP's and their extended number of spent fuel rods -up to sometimes 7 cores (cited in this document)- whereas the initial design (and safety considerations) was only for 1/3 of a core...

This doc (published in 1996!) clearly illustrates the increases of risks due to the lack of spent fuel treatment options; so they accumulate in greater numbers over longer time in SFP, which is, based on this document, a much higher risk in terms of radioactive consequences than the ones associated with core damage (no containment, bigger amount of fuel, etc.).

Concerning the "bellows seal" whose temperature is rising at N°3 reactor (205°C currently), so this seal in fact is situated (if i understand properly) at the top end of the reactor: it seals the reactor vessel with the drywell, which is necessary during refuelling operations. During refuelling, the containment cap and the reactor cap are removed and water is poured in the well above the opened reactor. This seal is used to create the waterproof volume filled with water (the well). If this seal is leaking, then water during refuelling would leak directly into the containment vessel.

 

[jim hardy]

i too wonder about those explosions, especially unit 3, and await the condition of the reactor vessel & containment.

I doubt the fuel pool had anything beyond a zirc-water fire.
That is exothermic as you all well know, in fact reacting a pound of zirconium with water releases about 1/4 as many BTU's as burning a pound of coal with air. And of course a fair bit of hydrogen.
So a fast zirc-water fire would be a vigorous event that'd exhale a cloud of H2 ready to burn as soon as it got mixed with enough air.. that's sure plausible.

i am curious about the orange flash at beginning of #3 video, and if you find the right youtube there was one in first fraction of a second of unit 1 as well. Both orange flashes went horizontal.

As pointed out in someone's earlier post , i too thought hydrogen burned invisible and in unit 1 video you can sort of see a distortion in the air moving out and up in first few instants of blast.

<Speculation alert> might that be the hydrogen cloud igniting?

I'd post a link to a good video image , but last time i did that it disappeared from Youtube a few hours later.

Does anybody know of a frame by frame?

And is there anything to be gleaned from the burst of orange flame?
Orange is the color of burning salt but they weren't spraying seawater into the pools yet, as best i could find.

if this is just board clutter - advise and i'll desist. i troll for fish not attention.

old jim

 

[jim hardy]

[q]This doc (published in 1996!) clearly illustrates the increases of risks due to the lack of spent fuel treatment options; ...[/q]

now you're on the same soapbox i preach from.

We as a nation are not doing right by spent fuel. The promise was for a robust reprocessing industry to deal with it and that didn't happen.
John McPhee's book "The Curve of Binding Energy" is a fascinating glimpse into the whys.

if we aren't willing to do something well we shouldn't do it at all.

old jim

 

[Astronuc]

@Astronuc:

What type(s) of scattered debris following a hydrogen explosion might have a 900 mSv/hr activity? It would seem to me something from the SFP of Unit 3 would be at the top of the suspect list, but perhaps not so. Your opinion? Thanks.

Bearing in mind 1 rem = 1000 mrem = 10 mSv = 0.01 Sv

and 1 rad ~ 1 rem when referring to gamma and X rays.
http://www.ndt-ed.org/EducationResources/CommunityCollege/RadiationSafety/theory/Measures.htm

I've seen pieces of fuel rod, underwater with activities on the order of 1000s of rad/hr, or 10000s mSv/hr. I suspect that rebar was contaminated with Cs and I, so it had a count in air of ~ 900mSv/hr.

 

[RealWing]

Bearing in mind 1 rem = 1000 mrem = 10 mSv = 0.01 Sv

and 1 rad ~ 1 rem when referring to gamma and X rays.
http://www.ndt-ed.org/EducationResources/CommunityCollege/RadiationSafety/theory/Measures.htm

I've seen pieces of fuel rod, underwater with activities on the order of 1000s of rad/hr, or 10000s mSv/hr. I suspect that rebar was contaminated with Cs and I, so it had a count in air of ~ 900mSv/hr.

The big unknown for me as a former plant guy is - at what distance from the hot spot was the radiation measurement taken. The number is meaningless without this info. I'm sure they didt get too close to a 90 R/hr hot spot (at least I hope not!)

 

[Astronuc]

The big unknown for me as a former plant guy is - at what distance from the hot spot was the radiation measurement taken. The number is meaningless without this info. I'm sure they didt get too close to a 90 R/hr hot spot (at least I hope not!)

That's one of the many unknowns. How did they measure it - by robot or remote control vehicle, and how did the apply geometric factors?

 

[MiceAndMen]

Sorry if this has been discussed earlier.

France's IRSN has calculated that SFP 4 would lose max 115 tons per day.

http://www.world-nuclear.org/info/fukushima_accident_inf129.html

An extensive report with some highly suspect "factual information". They state that hydrogen was vented to the service floors intentionally.

Excess pressure from the wetwell (above 300 kPa) can be vented through the 120 m emission stack via a hardened pipe or into the secondary containment above the reactor service floor of the building.

The esteemed AREVA report by Matthias Braun makes the same claim on page 21. http://www.fairewinds.com/sites/default/files/AREVA%20Fukushima.pdf

Has it been established that there is a direct vent path from the primary containment to the reactor building service floor?

Or is this yet more bad information we'll just have to live with until the experts sort it all out for us after having collected data for a few more years?

The wno report also claims the explosion at Unit 4 further damaged Unit 3. That's a new one on me.

 

[rowmag]

rowmag really is example of the reason why government feels free to keep secrecy... a citizen who, in absence of data, would come up with his own explanations along the lines of how correct the government actions were. That is very convenient. Simple lack of specific data becomes effective positive propaganda in such cases.

First of all, I am not a citizen. Second of all, I have never said I thought the government actions were all correct. But there is another thread for that discussion.