Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[bytepirate]

An interesting question, indeed. Posited another way: If the emergency efforts to cool the reactor cores are (and it would seem, can only be) a temporary solution as long as the coolant (water) is not contained in a closed system,

Then only three alternatives exist:

1) Continue to spill contaminated water and slowly (relatively) contaminate the ground water and ocean while temporizing. (possibly, to allow time to deal with the spent fuel in the SFPs?), or

2) Somehow devise a stable, permanent system to contain, decontaminate and if possible, recirculate the water being used for cooling the cores (unlikely), or

3) Prepare to let the cores melt and deal with the consequences.

Is there another option I am missing? If not, then option (3), it seems, is most likely the "not if, but when" final event in the Fukushima disaster sequence.

Which begs the question: What might be done while temporizing with the current efforts to cool the cores to mitigate the ultimate consequences of one or more melted reactor cores with loss of the primary containment? If the answer to that question is "nothing effective", then, is option (1) with ongoing contamination by un-contained, highly contaminated water for as long as humanly possible worse than option (3)?

I don't know.

maybe they need a feynman (or any other brilliant mind, preferred alive) to come up with an unexpected fourth solution.
something like:
fill up the RPV with copper pellets, then pour in some radiator sealant (i have heard pepper and eggs are working), then cool the thing from the outside.

this is not a serious suggestion, but maybe the final solution will be something like that: unexpected, ridiculous - and working.

 

[83729780]

Is there another option I am missing?

I honestly think they're still considering the giant cloth. It's been mentioned twice in Kyodo news reports.

 

[Borek]

Considering that at d + almost 30 , they aren't any closer to restore cooling , if anything situation is worse , containment is not really containing , what option do they have ? They can't let it bleed out for ever ...

Amount of heat evolving should be getting down, even if there are short criticalities. Once the power gets down they can stop cooling. But I doubt there is much that can be done earlier.

 

[StrangeBeauty]

Pardon if this is a repost: They've issued corrections to a number of released readings/info including pressure readings for RPVs #1 and #3:

http://www.nisa.meti.go.jp/english/files/en20110411-3.pdf

[Edit]: There appears to be some new data for #3

 

[shogun338]

A fire broke out at Japan's crippled Fukushima Daiichi nuclear power plant, operator Tokyo Electric and Power (TEPCO) said on Tuesday, although flames and smoke were no longer visible. http://www.reuters.com/article/2011/04/11/idUSL3E7FB1YD20110411

 

[shogun338]

Magnitude 6.6 - EASTERN HONSHU, JAPAN
2011 April 11 08:16:13 UTC http://earthquake.usgs.gov/earthquakes/eqinthenews/2011/usc0002n9v/

 

[Astronuc]

They just had a mag 6.2 down near the Tokai plant.
http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/usc0002nzx.php
Date-Time:
Monday, April 11, 2011 at 23:08:16 UTC
Tuesday, April 12, 2011 at 08:08:16 AM at epicenter

Location: 35.406°N, 140.542°E
Depth: 13.1 km (8.1 miles)

Distances:
77 km (47 miles) ESE of TOKYO, Japan
82 km (50 miles) E of Yokohama, Honshu, Japan
106 km (65 miles) S of Mito, Honshu, Japan
140 km (86 miles) SSE of Utsunomiya, Honshu, Japan

 

[shogun338]

RPV temperatures remain above cold shutdown conditions in all Units, (typically less than 95 °C). In Unit 1 temperature at the feed water nozzle of the RPV is 228 °C and at the bottom of the RPV is 121 °C. In Unit 2 the temperature at the feed water nozzle of the RPV is 149 °C. The temperature at the bottom of the RPV was not reported. In Unit 3 the temperature at the feed water nozzle of the RPV is 92 °C and at the bottom of the RPV is 111 °C. With the temperature being over 428 degrees Fahrenheit at the feed nozzle does this indicate that fission is still occurring inside Unit 1 ? http://www.iaea.org/newscenter/news/tsunamiupdate01.html

 

[SredniVashtar]

They have raised the level to 7
http://www.bbc.co.uk/news/world-asia-pacific-1304534

Japanese authorities have raised the measure of severity of their nuclear crisis to the highest level, officials say.
The decision was taken due to radiation measured at the damaged Fukushima Daiichi power plant, NHK reported.
"This is a preliminary assessment, and is subject to finalisation by the International Atomic Energy Agency," said an official at the Nuclear and Industrial Safety Agency (NISA)
The decision to raise the threat level was made after radiation of 10,000 terabequerels per hour had been estimated at the stricken plant for several hours.​

 

[Astronuc]

RPV temperatures remain above cold shutdown conditions in all Units, (typically less than 95 °C). In Unit 1 temperature at the feed water nozzle of the RPV is 228 °C and at the bottom of the RPV is 121 °C. In Unit 2 the temperature at the feed water nozzle of the RPV is 149 °C. The temperature at the bottom of the RPV was not reported. In Unit 3 the temperature at the feed water nozzle of the RPV is 92 °C and at the bottom of the RPV is 111 °C. With the temperature being over 428 degrees Fahrenheit at the feed nozzle does this indicate that fission is still occurring inside Unit 1 ? http://www.iaea.org/newscenter/news/tsunamiupdate01.html

The temperatures on Unit 1 are puzzling, and the Unit 3 temperatures are problematic.

 

[I_P]

An interesting article providing some details of the first two days of the accident:

http://www.yomiuri.co.jp/dy/national/T110411004567.htm"

 

[Bodge]

Confusion reigns in Japan:

11:14 NEWS ADVISORY: Radioactive materials from Fukushima plant 10% of amount from Chernobyl

11:39 NEWS ADVISORY: Fukushima different from Chernobyl, without massive radiation leak: agency

12:09 NEWS ADVISORY: Radiation leak may exceed amount in Chernobyl accident: TEPCO

http://english.kyodonews.jp/news/"

 

[JustGuessing]

The temperatures on Unit 1 are puzzling, and the Unit 3 temperatures are problematic.

Astronuc,

Thank you so much for all the information you have supplied during this past month.

This forum has been invaluable as I struggle to understand what all the data, and corrected data, and crazy theories, mean to everyone living near the nuclear plants -- and the future of nuclear power.

Your insights are great. And now I must also thank you for saying when the data points are simply puzzling. Sometimes the explanation is not clear...hopefully we'll get more data soon that will help us understand the situation on the ground better.

-- JustGuessing

P.S. A month in, how do you think they are doing? What are you most concerned about? C an you start to image the cleanup?

 

[liamdavis]

With respect to this the information contained in this report.

"

http://www.f.waseda.jp/okay/news_en...ower_Plants_suffered_big_eart_quake110331.pdf

Pg5
Emergency DGs started at the earthquake. But Tsunami damaged ultimate heat sinks (sea water pumping and cooling system) of units 1F1-4. caused common cause failure
•Without ultimate heat sink, Emergency DG (need to remove its generated heat for operation) and spent fuel pool cooling do not work.

Pg6
2:46pm: The earthquake happened. Plants automatically shut down. Offsite power lost. Emergency DG started up.
•3:42pm Emergency DG(diesel generator) stopped due to loss of equipment cooling water. (Tsunami was bigger than expected.) All AC power was lost for 1F1-4 and consequential isolation from UHS(ultimate heat sink), except for IC (isolation cooling system) in 1F1. RCIC(reactor core isolation cooling system) in 1F 2 Blackout + (mostly) loss of UHS"

When I worked on the construction of Pilgrim 1 in 1970 the diesel generators were radiator cooled, each had six starters, each starter had its own energy source and on site was a minimum of six months of fuel. In other words it was independently self sufficient, as an emergency system should be.

The system described in the publication above sounds like back up power for convenience. It was dependent upon, and assumed the the continued operation of, systems external to itself "sea water pumping and cooling system" for any operation.

I can understand a sea water-to-coolant heat exchanger in addition to a water-to-air heat exchanger, but not instead of it. I am,of course, assuming that the design purpose is the protection of human life.

I maintain commercial aircraft and I would not want to be responsible for maintaining anything designed by people who thought out the emergency(?) power system at Daiichi.

 

[shogun338]

Emergency Preparedness and Response to Radiation . What Preparations Can I Make for a Radiation Emergency
Your community should have a plan in place in case of a radiation emergency. Check with community leaders to learn more about the plan and possible evacuation routes. http://www.bt.cdc.gov/radiation/emergencyfaq.asp

 

[shogun338]

How close are you to a nuclear plant ? Are you in the 50-mile exclusion zone ? This map will show you how close you are in case of an accident . http://d3fjco7hozu03c.cloudfront.net/index.html

 

[AntonL]

Confusion reigns in Japan:

11:14 NEWS ADVISORY: Radioactive materials from Fukushima plant 10% of amount from Chernobyl

11:39 NEWS ADVISORY: Fukushima different from Chernobyl, without massive radiation leak: agency

12:09 NEWS ADVISORY: Radiation leak may exceed amount in Chernobyl accident: TEPCO

http://english.kyodonews.jp/news/"

Confusion reigns in Kyodo,

http://english.kyodonews.jp/news/2011/04/84828.html"

''The radiation leak has not stopped completely and our concern is that the amount of leakage could eventually reach that of Chernobyl or exceed it,'' an official from the Tokyo Electric Power Co. said ... however, that the amount of radioactive materials released from the nuke plant is estimated to be about 10 percent of the amount released in the Chernobyl accident.

 

[Cire]

RPV temperatures remain above cold shutdown conditions in all Units, (typically less than 95 °C). In Unit 1 temperature at the feed water nozzle of the RPV is 228 °C and at the bottom of the RPV is 121 °C. In Unit 2 the temperature at the feed water nozzle of the RPV is 149 °C. The temperature at the bottom of the RPV was not reported. In Unit 3 the temperature at the feed water nozzle of the RPV is 92 °C and at the bottom of the RPV is 111 °C. With the temperature being over 428 degrees Fahrenheit at the feed nozzle does this indicate that fission is still occurring inside Unit 1 ? http://www.iaea.org/newscenter/news/tsunamiupdate01.html

All these temperature sensors where cooked (ie. Damaged). They greatly exceeded their operating temperature. I don't believe these numbers are accurate. The feed nozzle is the point where the cold water is being injected and has probably the highest temperature drop because of the flow rate and temperature difference.

If these temperatures where accurate we'd be seeing the steam equivalent of 8 cubic meters of water per hour pouring out the reactor somewhere. Not cold water leaking into trenches and pouring into the ocean.

The feedwater temperatures being reported are very close to what you see when the reactor is running. You can read more about these measurements and how you can get gradients in the plumbing here: http://www.google.com/url?sa=t&sour...tn6DA&usg=AFQjCNH_z5TkAmOzCywqIAMaB7-JoVijFQ"

 

[Cire]

How close are you to a nuclear plant ? Are you in the 50-mile exclusion zone ? This map will show you how close you are in case of an accident . http://d3fjco7hozu03c.cloudfront.net/index.html

I'm about 12 miles from a plant. I get a free packet of Potassium Iodide in the mail each year. I also keep my dosimeter and Geiger counter running

I'm glad the plant is there, even knowing the risks.

 

[sp2]

P.S. One more question:

I've been asking this of various people in various places for a couple of weeks now, and I've yet to hear a convincing answer: If the reactors shut down on March 11, and the half-life of I-131 is 8 days, and we were assured, therefore, by every Pompous Nuclear Pundit from Day 1 that the Iodine was a transient problem that would disappear in a jiffy... why is it that we're still seeing so damn much I-131, everywhere we look, what, FOUR half-lives out, now??

What gives? How many half-lives do we have to go, before someone starts to wonder what the hell is going on?

Forgive me if there's an obvious explanation for this, but I'm really having a hard time seeing it.
(If it *is* just a case of normal decay of the initial products, then what the heck does that say about the quantities that were originally released? They'd have to be pretty huge, no?)

Thanks again.

 

[shogun338]

Map of Radiation Measurements by Greenpeace team http://maps.google.com/maps/ms?ie=U...581055&spn=0.761327,1.647949&z=9&source=embed

 

[shogun338]

I'm about 12 miles from a plant. I get a free packet of Potassium Iodide in the mail each year. I also keep my dosimeter and Geiger counter running

I'm glad the plant is there, even knowing the risks.

I'm 20 miles from Plant Hatch in Georgia and receive no Potassium Iodide and no alert radio . My relatives that live closer to the plant receive all that . I think they should expand the zone considering the event in Japan . There are dozens of towns in this area that would be affected in a accident at the plant such as a fire in the spent fuel pool . I have a lot of friends that work in the plant that are glad its there too. I know we need nuclear energy but we all need to ensure it it made safer .

 

[Bodge]

After 2 weeks without a report, the sensor at the bottom of reactor 2's RPV is showing 208.1C

http://www.meti.go.jp/press/2011/04/20110412002/20110412002-3.pdf

http://atmc.jp/plant/temperature/?n=2

This is the highest reported temp at that location.

Also, possible context via Kyodo, 12:22 12 April

"BREAKING NEWS: Released radioactivity comes mostly from No. 2 reactor blast March 15"​

Discuss!

 

[AntonL]

A fire broke out at Japan's crippled Fukushima Daiichi nuclear power plant, operator Tokyo Electric and Power (TEPCO) said on Tuesday, although flames and smoke were no longer visible. http://www.reuters.com/article/2011/04/11/idUSL3E7FB1YD20110411

http://www.tepco.co.jp/en/press/corp-com/release/11041202-e.html

At approximately 6:38 AM, April 12th, fire has been found at the
distribution switchboard containing batteries located in the sampling
equipment switchbox situated close to the south water discharge channel
for Units 1-4

 

[shogun338]

After 2 weeks without a report, the sensor at the bottom of reactor 2's RPV is showing 208.1C

http://www.meti.go.jp/press/2011/04/20110412002/20110412002-3.pdf

http://atmc.jp/plant/temperature/?n=2

This is the highest reported temp at that location.

Also, possible context via Kyodo, 12:22 12 April

"BREAKING NEWS: Released radioactivity comes mostly from No. 2 reactor blast March 15"​

Discuss!

I don't see in the link where the sensor for bottom of RPV is showing readings in Unit 2 after 3-30-11 .

 

[NUCENG]

P.S. One more question:

I've been asking this of various people in various places for a couple of weeks now, and I've yet to hear a convincing answer: If the reactors shut down on March 11, and the half-life of I-131 is 8 days, and we were assured, therefore, by every Pompous Nuclear Pundit from Day 1 that the Iodine was a transient problem that would disappear in a jiffy... why is it that we're still seeing so damn much I-131, everywhere we look, what, FOUR half-lives out, now??

What gives? How many half-lives do we have to go, before someone starts to wonder what the hell is going on?

Forgive me if there's an obvious explanation for this, but I'm really having a hard time seeing it.
(If it *is* just a case of normal decay of the initial products, then what the heck does that say about the quantities that were originally released? They'd have to be pretty huge, no?)

Thanks again.

After 4 half lives 1/16 of the I-131 is still there. Based on an initial source term of about 75 MILLION Curies there are still 4.7 million Ci on site or somewhere down wind that haven'r decayed yet. Half of a big number is still a big number.

 

[hbjon]

I'm pondering what you're pondering sp2. I've only had a sunday supplement course on all this jazz, but maybe that I-131 is the reason for the heightened alert. Atomic Mass of 131 doesn't seem like a natural decay atom of U-238. And again, I am no authority on the subject. But, when you have high energy particles flying around, I speculate that quite a bit of artificial transmutation will cause the formation of that particular radioisotope.

 

[AntonL]

At 14:07 another 6.0 aftershock strikes at 14km distance from yesterdays 6.6 and 52km from Fukushima I

Workers ordered once again to evacuate the stricken plant

 

[shogun338]

Just watched TEPCO new drone video and was going to post it but quality is so bad its worthless ! Pics to show bad quality ! I hope they have better shots that there not releasing . It does show steam still coming from Unit 3 spent fuel pool and reactor location . Looks like even more . Unit 4 steam or smoke coming from turbine facing side out of blowout in wall if you look close .

 

[shogun338]

Pic of the tsunami in the plant . Before and after .

 

[Maxion]

Pic of the tsunami in the plant . Before and after .

That's Daiini, not Daiichi.

 

[jpquantin]

Confusion reigns in Kyodo,

http://english.kyodonews.jp/news/2011/04/84828.html"

BBC report has some errors.

Total Chernobyl radiation leakage was http://www.iaea.org/Publications/Magazines/Bulletin/Bull383/dreicer.html" between 1332 and 1847 peta-bq (10^15).

BBC reports of 630,000 tera-bq (10^12) per hour http://www.bbc.co.uk/news/world-asia-pacific-13045341" .

"The decision to raise the threat level was made after radiation of up to 630,000 terabequerels per hour had been estimated at the stricken plant for several hours.

That would classify the crisis at level seven on the International Nuclear and Radiological Event Scale (Ines).

It was not clear when that level had been reached. The level has subsequently dropped to less than one terabequerel an hour, reports said."​

They add:

"In comparison the Japanese government said the release from Chernobyl was 5.2 million terabecquerels."​

Chernobyl estimated in IAEA document: 1.332 - 1.847 10^18 bq.
Chernobyl for the Japanese government: 5.2 10^18 bq

Now 630,000 tera-bq per hour is 630 10^15 bq, or 0.63 10^18 bq. Several hours would mean at least 2, so they estimate minimal release to 1.26 10^18 bq. This is between a quarter and a full Chernobyl (in a few hours).

Kyodo http://english.kyodonews.jp/news/2011/04/84888.html" a TOTAL of 0.37 - 0.63 10^18 bq, which is between a tenth and a half Chernobyl.

 

[AntonL]

Confusion spreads ... Either this is not tera, or it is between a quarter and a full Chernobyl (in a few hours), or I've made an error in my maths (or I shouldn't try to understand amid distorted information).

extract from http://www.meti.go.jp/press/2011/04/20110412001/20110412001-1.pdf
[PLAIN]http://k.min.us/imDj6O.JPG

Col 1 - Fukushima NISA estimate
Col 2 - Fukushima Safety Commission estimate
Col 3 - Tschernobyl case

Row 1 = I-131 (a)
Row 2 = Cs-137
Row 3 = Cesium in terms of Idodine (b)
Row 4 = (a)+(b)

The column 3 figures for CS-137 an I-131 you should find in the Tschernobyl literature (upper limit)

 

[clancy688]

Confusion spreads ...

Total Chernobyl radiation leakage was http://www.iaea.org/Publications/Magazines/Bulletin/Bull383/dreicer.html" between 1332 and 1847 peta-bq (10^15).

That's the total activity based on all sources at time of the release. INES is using radioactivity numbers different...
The total discharge is calculated as an amount of I131 equivalence - you're basically taking a table from the INES-manual which gives you different factors for every released isotope. For example, C137 radioactivity release * 40 => equivalent radioactivity release for I131.

BBC reports of 630,000 tera-bq (10^12) per hour http://www.bbc.co.uk/news/world-asia-pacific-13045341" .

That's probably an error. NSC sets the total discharge of I131 and C137 in I131 equivalence at 630.000 Tbq.

http://www.nisa.meti.go.jp/english/files/en20110412-4.pdf

"In comparison the Japanese government said the release from Chernobyl was 5.2 million terabecquerels."​

INES manual tells us total amount of radioactivity release at Chernobyl in I131 equivalence is around 5.400.00 TBq. And in their INES 7 paper, NISA states, that the total amount of I131 and C137 released during Chernobyl is 5.2 * 10^18 Bq I131 equivalence:
Chernobyl I131 was 1.8 * 10^18 Bq and C137 was 8.5 * 10^16 Bq. Those are also the numbers I'm familiar with. And now (1 * 1.8 * 10 ^ 18) + (40 * 8.5 * 10^16) = 5.2 * 10^18 Bq

Chernobyl estimated in IAEA document: 1.332 - 1.847 10^18 bq.
Chernobyl for the Japanese government: 5.2 10^18 bq

I don't know from where you get your 1.332 - 1.847 * 10^18 numbers - I can't find them in your linked IAEO document. The link you provided us tells something about 2 EBq of I131, which's 2*10^18 -> 2000 * 10^15

 

[bytepirate]

Col 1 - Fukushima Nisa Estimte
Col 2 - Fukushima Dafety commision estimate
Col 3 - Tschernobyl case

Row 1 = I-131 (a)
Row 2 = Cs-137
Row 3 = Cesium in terms of Idodine (b)
Row 4 = (a)+(b)

available in english as well: http://www.nisa.meti.go.jp/english/files/en20110412-4.pdf

another question:
tepco is concerned, that the radiation may reach the chernobyl values.
http://english.kyodonews.jp/news/2011/04/84828.html

as the radiation currently leaks much slower than before, this would mean, that they expect/fear that the current situation lasts *for years* ?

 

[artax]

An interesting article providing some details of the first two days of the accident:

http://www.yomiuri.co.jp/dy/national/T110411004567.htm"

Fascinating reading that!... and it doesn't surprise me, TESCO seem to have dithered and been indecisive throughout this disaster.

 

[jpquantin]

AntonL, clancy688,

I wasn't aware of this iodine 131 equivalence. Thank you for clarifying!

 

[artax]

Just watched TEPCO new drone video and was going to post it but quality is so bad its worthless ! Pics to show bad quality ! I hope they have better shots that there not releasing . It does show steam still coming from Unit 3 spent fuel pool and reactor location . Looks like even more . Unit 4 steam or smoke coming from turbine facing side out of blowout in wall if you look close .

Can't agree more! Those drone videos are terrible. Like someone else said, US military totally wating money if that's the best they can do! A 300 dollar RC helicopter with a 200 dollar 12MP digital camera, (suspended on rubber bands for the vibration) and a 32GB sdcard would be far superior!

 

[Krikkosnack]

I have some questions ...

1) Only one microgram of plutonium can kill a man, so : Is it possible to measure the alpha and beta particles of a microgram of plutonium in the food? In other words : How the people of Japan can be protected now from nuclear pollution in food?

2) Normally We measure only the gamma ray from plutonium and uranium with the standard geiger counter?

3) Due to the type of Hydrogen explosion of reactor (different from Chernobyl), can we generate a list of all the isotopes that we will retrieves on power plant site?

 

[Bodge]

I don't see in the link where the sensor for bottom of RPV is showing readings in Unit 2 after 3-30-11 .

It was on the pdf, http://atmc.jp/plant/temperature/?n=2 shows 208.1C now

 

[Bodge]

I have some questions ...

1) Only one microgram of plutonium can kill a man, so : Is it possible to measure the alpha and beta particles of a microgram of plutonium in the food? In other words : How the people of Japan can be protected now from nuclear pollution in food?

2) Normally We measure only the gamma ray from plutonium and uranium with the standard geiger counter?

3) Due to the type of Hydrogen explosion of reactor (different from Chernobyl), can we generate a list of all the isotopes that we will retrieves on power plant site?

I want to know where all the Strontium is.

Are TEPCO only testing for certain isotopes?

 

[tsutsuji]

I don't see in the link where the sensor for bottom of RPV is showing readings in Unit 2 after 3-30-11 .

I attach the bottom of page 1 of http://www.meti.go.jp/press/2011/04/20110412002/20110412002-3.pdf

 

[clancy688]

Are TEPCO only testing for certain isotopes?

Only I131, Cs134 and Cs137. No other isotopes because of some errors with other substances than those three during the last weeks.

 

[biggerten]

With respect to this the information contained in this report.

"



When I worked on the construction of Pilgrim 1 in 1970 the diesel generators were radiator cooled, each had six starters, each starter had its own energy source and on site was a minimum of six months of fuel. In other words it was independently self sufficient, as an emergency system should be.

The system described in the publication above sounds like back up power for convenience. It was dependent upon, and assumed the the continued operation of, systems external to itself "sea water pumping and cooling system" for any operation.

I can understand a sea water-to-coolant heat exchanger in addition to a water-to-air heat exchanger, but not instead of it. I am,of course, assuming that the design purpose is the protection of human life.

I maintain commercial aircraft and I would not want to be responsible for maintaining anything designed by people who thought out the emergency(?) power system at Daiichi.

I wonder if we don't have translation issues here. The way I read that, it doesn't mean that cooling for the generators themselves was lost, but that the pumps that the diesels were to operate had nothing to pump. Perhaps the tsunami took out plumbing from the ocean or some heat exchange equipment. Diesels themselves require special coolant (SCA or OAT) to prevent internal damage (cavitation damage to cylinder sleeves, etc), sea water use would be extremely short term as a coolant in a diesel.

 

[AntonL]

I want to know where all the Strontium is.

Are TEPCO only testing for certain isotopes?

Tepco are testing but not releasing, in their own words

http://www.tepco.co.jp/en/press/corp-com/release/11041106-e.html]Regarding[/URL] the results on three nuclides (iodine 131, cesium 134,
cesium 137), we would like to assume those as definite result, however,
as for other nuclides, we will revaluate in accordance with the
preventive measures formulated after being given warning from Nuclear and
Industrial Safety Agency on April 1st.

and

http://www.tepco.co.jp/en/press/corp-com/release/11041106-e.html]Three[/URL] nuclides (Iodine-131, Cesium-134 and Cesium-137) are released as
fixed figures. Other nuclides figures are to be released as soon as
identified under instruction of NISA.

 

[gmax137]

... on site was a minimum of six months of fuel...

I think you're mis-remembering, or someone gave you bad info in 1970. Standard Tech Specs call for seven days diesel fuel onsite. There may be more fuel, but it wouldn't be in seismic storage tanks, and it wouldn't be available to the emergency diesels without manually opening cross ties and possibly using non-safety related transfer pumps. And I really doubt the six month figure. That would be over 3/4 million gallons per diesel generator (taking a swag at 200 gph). I've never seen diesel fuel tanks that size at a nuclear unit.

 

[tsutsuji]

Just watched TEPCO new drone video

Could you please post a link to that video ?

 

[artax]

some of it is here, not exactly close up is it!

http://www.youtube.com/watch?v=V0R7EoD752Q&feature=feedu

 

[Zoe Brain]

My knowledge of the radiation issue is almost zero, based on an NBCD warfare course I did 35 years ago.

I am however a safety-critical systems engineer, and am looking for lessons to be learned for hazard mitigation.

My initial thought is that another Tsunami from an aftershock at this point would ruin their whole day, and I don't like the way the seismic activity graph is trending. We should put mitigation strategies into effect for that *now*.

Long-term, for future designs - Assuming catastrophic loss of coolant/cooling ability, is there any way of designing a reactor to melt-safe? Split the pellet mounds into manageable masses when they're released from damaged rods via a ribbed inverted cone under the core, keep them well boronated, and divert via chutes into heatsink containers easy to enclose and remove for later action?

Right now, we're spreading really impossibly dangerous levels of contamination in the localised area, (and unacceptable levels of Cesium far and wide) just to stop a melthrough. Is it worth it? We have a number of reactprs not in cold shutdown, we're flushing water through them and transporting masses of volatiles out of containment and into the environment. The Iodine-131's dangerous in the short term, but Cesium-134 is the main worry for me. Half of that's still there in 30 years.

Storing spent fuel rods in situ now seems to be a really complicating factor when things go pear-shaped. Trouble is, I can't see a safer way of dealing with them, transporting them and their attendant coolant pool, even in small masses, to a remote site a few hundred metres away seems fraught with hazard. Maybe an automated shuttle tank, similar in concept to what they do with cooled-off rods, but far more dangerously hot.

 

[Borek]

Long-term, for future designs - Assuming catastrophic loss of coolant/cooling ability, is there any way of designing a reactor to melt-safe?

Yes. Astronuc will be able to give more details, but it is definitely possible and newer designs are already going in this direction. Check http://en.wikipedia.org/wiki/Passive_nuclear_safety

Right now, we're spreading really impossibly dangerous levels of contamination in the localised area, (and unacceptable levels of Cesium far and wide) just to stop a melthrough. Is it worth it? We have a number of reactprs not in cold shutdown, we're flushing water through them and transporting masses of volatiles out of containment and into the environment.

Alternative can be much worse. If temperatures go up we may have more explosions and much more contamination, thus stabilizing the reactors is probably the best thing that can be done at the moment.