Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[artax]

Still not looking good then, the news I've seen over the past two days has been reporting ludicrously optimistic statements like 'workers are reconnecting power to the stricken fukushima plant, in the hope of restoring cooling to the four reactors'
They need lots of help I feel from some disaster experienced engineers.
Reactor 1, blimey! they've been more concerned about 3 and 4, 1 is the least damage isn't it? maybe they'd better focus on two now!
Looks like we'll have black smoke from all 4 reactors by tomorrow.

 

[|Fred]

latest (exept t° went down to 330° in unit 1)
[PLAIN]http://i.min.us/ika7oo.jpg
[PLAIN]http://i.min.us/ijW5Ti.jpg

 

[jlduh]

@ FRED: ca you give the direct link to these two very informative pages?

Can somebody confirm the pressure readings: we talk about relative pressure to atmospheric pressure and not absolute pressure, of course (just want to make it clear to anybody)?

By the looks of their protection they can't be THAT concerned about radiation levels, which is a good sign.

I'm not sure you saw in the US the documentary (in french language) La bataille de Tchernobyl (The Battle of Tchernobyl), done in 2005, right?

In case you would like to see it (the images and archives from Soviet autorities are worth to see even if you don't understand everything), you can view it in 5 parts here:

http://www.chernobyl-day.org/article/la-bataille-de-tchernobyl

or here

http://www.dailymotion.com/video/x6xbsg_la-bataille-de-tchernobyl-15_news
http://www.dailymotion.com/video/x6xbys_la-bataille-de-tchernobyl-2-5_news
http://www.dailymotion.com/video/x6xc90_la-bataille-de-tchernobil-3-5_news
http://www.dailymotion.com/video/x6xci0_la-bataille-de-tchernobyl-4-5_news
http://www.dailymotion.com/video/x6xcqa_la-bataille-de-tchernobyl-55_news

You will see how to deal with high levels of radioactivity in case of high emergency... One million people have worked on the "liquidation" of the crippled soviet reactor. Most of them have been killed or got sicked. Most of them didn't even know what they were risking. The ones who intervened on the reactor itself ("cleaning" the roof for example: All of them died) have been called the "bio robots", because they were replacing the failed robots whose electronics couldn't bear the radiations levels...

I don't know how this accident has been covered and disclosed in the US from the citizen standpoint and knowledge. Here in Europe but especially in France, we had to wait until 2005 and this documentary to have a easy to understand tool to really be able to imagine what really happened there during the days, weeks and months after the accident.

Of course the subject here in Europe and France was very "touchy" (french are one of the "leaders" in nuclear energy) but on the other hand we were much closer from the catastroph and (some) citizens stayed very concerned and "vaccinated" by the combination of relative proximity and unacceptable silence and disinformation by the autorities (french and soviet).

Did US people know this documentary by the way? I don't know if an english version exists (it should be the case...)

 

[|Fred]

My sources for the Japanese figure are those http://www.jaif.or.jp/english/index.php
My source for the French way of safety assessing risk is the parliamentary hearing that was held on the 16.03.2011 the " Assemblée nationale"

According to NHK word http://www3.nhk.or.jp/daily/english/23_28.html

163,000 becquerels of radioactive cesium-137 per kilogram of soil has been detected in Iitate Village, about 40 kilometers northwest of the plant.

I'm failing at maths here..

 

[Borek]

One million people have worked on the "liquidation" of the crippled soviet reactor. Most of them have been killed or got sicked.

That's simply not true (to not say it is a lie). There was no "million" people working there, and total number of deaths that can be attributed to the accident is below 100. Estimates of the number of deaths that occurred later are also much lower (several thousands), unless one takes into account Yablokov book - but IMHO his estimates are in one (cracked) pot with the Moon hoax.

And it makes no sense to compare authorities in soviet Russia with Japan government - completely different culture and completely different approach; democracy vs highly censored police state. Russians worked as if nobody was looking at their hands, that's not the case in Japan. I am not telling Japanese are not trying to hide some information, quite possible they do, but the scale is incomparable and they have no tools for a fast and effective implementation of censorship.

 

[jlduh]

Thanks Fred. Are you french by the way?

The level in Iitate village soil is horrendously high taking into account the distance from the plant.

Based on what i see from last 10 days at the plant and now around the plant (combined to the info about tap water for example in this area which is the most contaminated it seems because of the winds http://www3.nhk.or.jp/daily/english/23_29.html , but even tap water of Tokyo is now of concern for children), i think the autorities are losing day after day control of the situation... Leaving people in the 30 (but also probably the 60 or 80 kms zone) is now really problematic. But how move so many people in a so dense country? The Tchernobyl area was, from this stand point, a little bit easier to handle i think.

 

[jlduh]

I found links for english version of The Battle of Tchernobyl (it seems the english version is from 2007 so 2 years after the french one).

It is in many parts on Youtube (10 parts) listed on this page from 1 to 10:

http://www.youtube.com/results?search_query=jimdangello+the+battle+of+tchernobyl&aq=f

 

[M. Bachmeier]

T-Cups and Antoni must be auditioning for Fox or one of the other news groups. Using limited knowledge, convoluted science, and conjucture. BTW, radiologically clearing a place and entering a cleared place are to diametrically opposites. Evidently you have not worked in contaminated areas or had to cleared them. Pictures do not always tell the whole story...that is how Fox news and others get attention. Have you got enough yet?

I wonder if you would mind qualifying your expertise sir. You apparently have very strong opinions about other contributors to this thread. At least one of the people you have slammed has credentials in two fields of study.

And, comparing anyone to FOX is an insult of an order of magnitude greater than 9.0.

Please tell us all why you know so much...

 

[jlduh]

@FRED: I already saw the regular tables and pdf on the JAIF site but I don't find from their main page the schematics your present above (which are a neat and clear presentation). Could you precise where to find them on their site? Thanks!

 

[|Fred]

My bad it was on NISA's and to be specific there http://www.nisa.meti.go.jp/english/files/en20110323-2-2.pdf
And as far as your question is concerned, the answer is: I'm

ps: the above file is now obsolete.. the new one is http://www.nisa.meti.go.jp/english/files/en20110323-3-2.pdf

 

[jlduh]

Ok thanks FRED, found it. The page to consult is this one:

http://www.nisa.meti.go.jp/english/index.html

and from there "seismic damage information". Then of interest for the nuclear situation is:

A) Conditions of Fukushima Dai‐ichi Nuclear Power Station Unit 1 (the reactors charts above)
B) Day xx Monitoring Data: precise radioactivity measurements on various plants (especially DAICHII plant of course)

Bonjour à toi sinon!

 

[AntonL]

Todays black smoke

 

[Borek]

I wonder if you would mind qualifying your expertise sir. You apparently have very strong opinions about other contributors to this thread. At least one of the people you have slammed has credentials in two fields of study.

https://www.physicsforums.com/showpost.php?p=3197462&postcount=2

Dean Chaney, CHP
37 Years in the Nuclear Industry (Navy, DOE, NRC, Reactort/Facility Decommissioning Consultant)

 

[M. Bachmeier]

Thank you Borek (re: post 917), but I don't think it is necessary to compare anyone with FOX news. I believe those contributors I refer to meant no harm and have just been caught up in a mystery or puzzle.
And, people often feel the need to help. Moreover, the lack of existing data (not made public) has only encouraged speculation.

 

[Borek]

Opinion on FOX News is on its way to became a banned topic, let's not touch it here (or at least - let's not continue, whatever has been said, has been said).

My understanding is that RD thinks there is too much speculation build on too thin knowledge. Can't say I disagree.

 

[rhody]

Since, the radiological protection staff at the reactors and emergency center are very competent, and you or I do not know the radiological situation being shown...then what you see is appropriate. Quit slamming stuff you probably know nothing about.

Dean Chaney, CHP
37 Years in the Nuclear Industry (Navy, DOE, NRC, Reactort/Facility Decommissioning Consultant)

Dean and/or Astronuc,

I would like to ask one or both of you a couple simple questions, if I understand correctly, with reactor #3 having the fuel that contains partial plutonium, I read the MOX wiki page http://en.wikipedia.org/wiki/MOX_fuel" . With that as background and an excerpt from the article: (please correct any inaccuracies that you see).

1. Does #3 have a special design to accommodate the MOX fuel ?
2. Does the MOX fuel heat faster, and cool slower, both in the reactor and in the spent fuel pools ?
3. If exposed to the air due to melting, what additional elements and in what quantities and toxicity from the MOX are released to the environment ?

Thanks in advance...

BTW, good job Borek, in keeping this thread on track, amazing that it has this many responses and for the most part has been trying to present accurate information, a credit to all who are doing their best to present accurate, timely information.

Rhody...

About 30 thermal reactors in Europe (Belgium, Switzerland, Germany and France) are using MOX[6] and a further 20 have been licensed to do so. Most reactors use it as about one third of their core, but some will accept up to 50% MOX assemblies. In France, EDF aims to have all its 900 MWe series of reactors running with at least one-third MOX. Japan aimed to have one third of its reactors using MOX by 2010, and has approved construction of a new reactor with a complete fuel loading of MOX. Of the total nuclear fuel used today, MOX provides 2%.[4]

Licensing and safety issues of using MOX fuel include:[6]

As plutonium isotopes absorb more neutrons than uranium fuels, reactor control systems may need modification.
MOX fuel tends to run hotter because of lower thermal conductivity, which may be an issue in some reactor designs.
Fission gas release in MOX fuel assemblies may limit the maximum burn-up time of MOX fuel.
About 30% of the plutonium originally loaded into MOX fuel is consumed by use in a thermal reactor. If one third of the core fuel load is MOX and two-thirds uranium fuel, there is zero net gain of plutonium in the spent fuel.[6]

All plutonium isotopes are either fissile or fertile, although plutonium-242 needs to absorb 3 neutrons before becoming fissile curium-245; in thermal reactors isotopic degradation limits the plutonium recycle potential. About 1% of spent nuclear fuel from current LWRs is plutonium, with approximate isotopic composition 52% 239
94Pu, 24% 240
94Pu, 15% 241
94Pu, 6% 242
94Pu and 2% 238
94Pu when the fuel is first removed from the reactor.[6]

 

[TCups]

All:

Those new to this forum, myself included, are here because we are hungry for good information regarding what has happened at Fukushima as a consequence of a natural disaster (quake, tsunami) and the chain of events that followed. This includes information about the actual damage, what caused it , and what it means to those who must now deal with it. There has been far more and better information exchanged here (yes, much of it speculative) than any network news outlets. Thank you all for contributing to my education.

But as for assigning any blame to TEPCO, or ascribing any particular motive to their actions or lack of actions as it relates to the consequences of a natural disaster, and what regulatory actions might be appropriate because of that: 1) I, for one, have no immediate interest, and 2) it becomes not only speculative, but risks becoming politically charged and very contentious. Neither is appropriate.

As a contrarian, one might ask, for example, if it were appropriate to plan for and build sea walls substantial enough to defend against a 15 meter tsunami around a particular power plant, then why not 15 meter sea walls around areas where the entire population of costal areas where of thousands of people died and properties were decimated, or, for that matter, around all of Japan? Let's not go there.

No offense was taken on my part, and if I have offended, or through ignorance, been overly speculative, then I stand corrected and humbly apologize for so doing. But surely the admonition from the PF Mentors to stay "on topic", which is, I believe, the nuclear power plants themselves, is entirely appropriate and constructive. Thank you for it. Keep the good information coming, please.

 

[joelupchurch]

Interesting article in the science section of NY Times today. Check it out before the paywall goes up.

http://www.nytimes.com/2011/03/22/science/22predict.html?pagewanted=1&ref=science"

Based on what the Geologists knew before March 11th, Fukushima was actually a pretty prudent place to put a Nuclear Reactor. Apparently the archeological records indicate there was a big tsunami in that area in 869 AD, but it was smaller than this one.

 

[AntonL]

Electricity is being connected, pumps are being tested and soon the external cooling should
be functional again, but how efficient will it be?

I redo a salt content estimation (https://www.physicsforums.com/showpost.php?p=3200617&postcount=702" was too high)
Assumption 1: Seawater injection rate 2 m3/hour as per https://www.physicsforums.com/showpost.php?p=3204597&postcount=906"
Assumption 2: Seawater salinity 34g/Litre or 34kg per m3 as per http://en.wikipedia.org/wiki/File:WOA05_sea-surf_SAL_AYool.png"

Today is the 11th day since sea water injection started and let's assume another two days
till pumps start working

--> 13 x 24hours x 2m3/hour x 34kg = 21216 kg salt

http://en.wikipedia.org/wiki/Solubility" degree C is 60g/100 liters or 600g per m3 of water
(or about 40g/100 l at room temperature thus we need to evaporate 90% of seawater for
crystallization to take place at room temp)

Therefore, to have a homogeneous solution of salty coolant we need:
21216/0.6 = 35360m3 of water

However the reactor is
5.4 metres in diameter and 19.2 metres high thus has an internal empty volume of 326 m3

The specific gravity of salt is 2.16 hence about 10 cubic metres of salt crystals will be in
the reactor vessel.

Anybody have an idea how this problem will be solved?

------------------------------------------------------------------------------

PS to Reno Deano - Electrical Engineer and Physicist here
fortunately never worked in the nuclear industry but in the power industry.

 

[Astronuc]

1. Does #3 have a special design to accommodate the MOX fuel ?
2. Does the MOX fuel heat faster, and cool slower, both in the reactor and in the spent fuel pools ?
3. If exposed to the air due to melting, what additional elements and in what quantities and toxicity from the MOX are released to the environment ?

1) Unit #3 does not have a special design. MOX fuel is designed to behave like a UO₂ assembly from a thermal standpoint. As I understand the available data, Unit 3 had 32 MOX assemblies - and probably not all fuel rods were MOX. They were part of a larger reload of on the order of 140-160 assemblies. One quarter of the core of 548 assemblies is 137, and they may reload slightly more or less depending on cycle length, capacity factor, and residual reactivity in the fuel. The MOX fuel can be placed in uncontrolled cells such that shutdown margin is not reduced.

Regarding

As plutonium isotopes absorb more neutrons than uranium fuels, reactor control systems may need modification.
MOX fuel tends to run hotter because of lower thermal conductivity, which may be an issue in some reactor designs.

PuO₂ and TU elements are dispersed in a UO₂ matrix. The portion of PuO₂ can be adjusted to an equivalence with a UO₂ assembly.

The thermal conductivity is slightly less than UO₂, but I don't consider that significant. One can design to control the power peaking. Fuel designers understand the difference between MOX and UO₂, so they can design to mitigate the effect of these differences.

The decay heat of MOX at a given burnup is slightly higher than UO₂, but that's not significant. After several months, I don't see the difference in decay heat being an issue.

2) MOX fuel may produce slightly more Xe, but less Kr, than UO₂ fuel at a given burnup. This fission gas release (Xe, Kr) from the fuel into the internal void volume may be slightly higher, but it's not significant IMO. See the attached figure for a comparison of fission product yields from thermal fissioning of U-235 and Pu-239.

3) The concern about MOX is due to the Pu istopes and transuranics (TU, or isotopes of Am, Cm) which are higher in MOX than UO₂ at the same burnup. The concern about fires involving nuclear fuel relates to the notion that some fuel particles may be released as aerosols and dispersed. A dispersed aerosol would increase the likelihood that folks could ingest or inhale the fuel particles. However, it is not clear to me that this is happening at Fukushima. Anytime there is a fuel failure, there is a concern about fuel particles escaping from the fuel rods and depositing within the reactor building.

Aside from U, Pu and other TU elements, the release of fission products from the fuel to the environment is a serious concern, regardless of the initial fuel matrix, e.g., MOX or UO₂.

Thanks in advance...

BTW, good job Borek, in keeping this thread on track, amazing that it has this many responses and for the most part has been trying to present accurate information, a credit to all who are doing their best to present accurate, timely information.

Rhody...

Thanks, Borek!

 

[intric8]

Just saw a news piece with DOH staff taking readings at the airport in counts per SECOND, yielding readings of 24cps off one traveler returning from japan and touting local background readings of "just" 6 cps. Question: why would any govt agency express readings in terms of cps instead of cpm, other than to downplay the exposures? this implies 1440cpm and 360cpm respectively, does it not? hope i am missing something here

 

[shadowncs]

Anybody have an idea how this problem will be solved?

10 cubic meters of salt would mean about 0.4 m of sediment layer if it were to settle (which it will not). As long as it is sloshy it can be moved by water pressure which is good.

If the main inlet to the PV is free of compact salt crystals (my guess is it will be) then they can pump in fresh water and steadily dissolve the salt by pumping in more water. No idea what they will do with the discharged water - they can't recirculate it and it is bound to be contaminated, heavily at first.

I remember reading about a filter system reactors have that filters any reactor water contaminants that are generated during regular use. Could this be used maybe?

While I love physics, I'm a software engineer so don't take my word for it.

 

[bondboy]

From Reuters: "Radiation at the crippled Fukushima No.2 nuclear reactor was recorded at the highest level since the start of the crisis, Japan's nuclear safety agency said on Wednesday. An agency spokesman said 500 millisieverts per hour of radiation was measured at the No.2 unit on Wednesday. Engineers have been trying to fix the plant's cooling system after restoring lighting on Tuesday."

from Kyodo:

Electric Power Co. said Wednesday it has observed a neutron beam, a kind of radioactive ray, 13 times on the premises of the Fukushima Daiichi nuclear plant after it was crippled by the massive March 11 quake-tsunami disaster.

TEPCO, the operator of the nuclear plant, said the neutron beam measured about 1.5 kilometers southwest of the plant's No. 1 and 2 reactors over three days from March 13 and is equivalent to 0.01 to 0.02 microsieverts per hour and that this is not a dangerous level.

Not trying to flame the fire here. The rad levels are low and I'm hoping TEPCO continues to make progress controling the site but the neutron beam got me thinking about reactor integrity. Neutron beams are product of fission correct? Would this finding confirm reactor damage even if it's just a pin hole?

 

[KateB]

I was actually just going to query on the neutron beam reported 1.5 km from the Fukushima nuclear plant. As a Biochem undergrad, my knowledge of physics is rudimentary at best, but wouldn't a neutron beam offsite signify release of plutonium/uranium, and to extrapolate further, does this mean that one of the spent fuel pools blew fissable material "sky-high"? What are the implications of this news? I have been following this thread for a while, and this has been a great pool of knowledge and learning for me.

 

[Reno Deano]

Just saw a news piece with DOH staff taking readings at the airport in counts per SECOND, yielding readings of 24cps off one traveler returning from japan and touting local background readings of "just" 6 cps. Question: why would any govt agency express readings in terms of cps instead of cpm, other than to downplay the exposures? this implies 1440cpm and 360cpm respectively, does it not? hope i am missing something here

They do that because they are not adquately trained or experienced HPs. CPS or CPM does not mean much unless you know the calibration of the instrument and radiation being detected. Hell, they could have been standing next to a pile of paper or within a high granite cement structure. I once had to do a followup survey of a building, (was currently a paper supply company) that was formerly use to make spacecraft parts using sightly enriched Thorium (60's). Between the stacks of paper the readings were about .3 to .8 mR per hour. All due to natural primordial Uranium and its daughter products.

 

[TCups]

Essentially what Kate is asking: What is the attenuation of neutron beams in air, and if a 0.01-0.02 microSievert source was detected, how far from the source of the neutron emission, if it were for example a fuel rod, might that be measured?

 

[artax]

No real news as such but some images of inside the control room, I'd like to know what guages they're looking at and the readings on them!
http://www.dailymail.co.uk/news/art...side-Japans-stricken-nuclear-power-plant.html

 

[83729780]

No idea what they will do with the discharged water - they can't recirculate it and it is bound to be contaminated, heavily at first.

it is returned to the ocean

http://hubpages.com/hub/Japan-May-Face-Even-Hotter-Water

...officials at Fukushima have confirmed that some of the water used to cool the reactors was returned to the sea after use.

 

[shadowncs]

it is returned to the ocean

If that is the case than the discarded sea water would carry away much of the concentrated NaCl from reactors which should make subsequent pumping less prone to failure.

 

[AntonL]

Wed Mar 23, 2011 5:46pm GMT
(Reuters) - The release of two types of radioactive particles in the first 3-4 days of Japan's nuclear crisis is estimated to have reached 20-50 percent of the amounts from Chernobyl in 10 days, an Austrian expert said Wednesday.

http://uk.reuters.com/article/2011/03/23/us-japan-quake-radiation-chernobyl-idUKTRE72M6OV20110323"

Remember Chernobyl also released huge amounts of nuclear material other than the isotopes mentioned above which have not been released at Fukushima

 

[83729780]

http://www.dailymail.co.uk/news/art...side-Japans-stricken-nuclear-power-plant.html

Five are believed to have already died and 15 are injured while others have said they know the radiation will kill them.

is this corroborated by other sources? Is there public information on levels of exposure?

 

[|Fred]

NISA it updating this every day several time a day.. I don't know where the press get there "stuff", I thought they were long gone from Japan ..



2. Exposure of workers
(1) As for the 18 workers conducting operations in Fukushima Dai-ichi NPS, results of measurements are as follows;
One worker: At the level of exposure as 106.3 mSv, no risk of internal exposure and no medical treatment required.
Other workers: At the level of no risk for health but concrete numerical value is unknown.
(2) As for the 7 people working at the time of explosion at around the Unit 3 of Fukushima Dai-ichi NPS who were injured and conscious, 6 out of 7 people were decontaminated by an industrial doctor of the clinic in Fukushima Dai-ni NPS, and confirmed to have no risk. The other one was decontaminated at the clinic and the medical treatment was completed.

3. Others
(1) Fukushima Prefecture has started the screening from 13 March. It is carried out by rotating the evacuation sites and at the 12 places (set up permanently) such as health offices. The results of screening are being totalled up.
(2) 5 members of Self-Defence Force who worked for water supply in Fukushima Dai-ichi NPS were exposed. After the work (March 12th), 30,000 cpm was counted by the measurement at Off site Centre. The counts after decontamination were between 5,000 and 10,000 cpm. One member was transferred to National Institute of Radiological Sciences. No other exposure of the Self-Defence Force member was confirmed at the Ministry of Defence.

(3) As for policeman, the decontaminations of two policemen were confirmed by the National Police Agency. Nothing unusual was reported.

<Situation of the injured (As of 19:00 March 23rd)>

1. Injury due to earthquake
- Two employees (slightly)
- Two missing (TEPCO’s employee, missing in the turbine building of Unit 4)
- One emergency patient (According to the local prefecture, one patient of cerebral infarction was transported by the ambulance).
- Ambulance was requested for one employee complaining the pain at left chest outside of control area (conscious).
- Two employees complaining discomfort wearing full-face mask in the main control room were transported to Fukushima Dai-ni NPS for a consultation with an industrial doctor.
2. Injury due to the explosion of Unit 1 of Fukushima Dai-ichi NPS
- Four employees were injured at the explosion and smoke of Unit 1 around turbine building (non-controlled area of radiation) and were examined by Kawauchi Clinic.
3. Injury due to the explosion of Unit 3 of Fukushima Dai-ichi NPS
- Four TEPCO’s employees
- Three subcontractor employees
- Four members of Self-Defence Force (one of them was transported to National Institute of Radiological Sciences considering internal possible exposure. The examination resulted in no internal exposure. The member was discharged from the institute on March 16th.)
4. Other injuries
- A person who visited the clinic in Fukushima Dai-ni NPS from a transformer sub-station, claiming of a stomach ache, was transported to a clinic in Iwaki City, because the person was not contaminated

 

[PietKuip]

NISA it updating this every day several time a day.. I don't know where the press get there "stuff", I thought they were long gone from Japan ..

2. Exposure of workers
(1) As for the 18 workers conducting operations in Fukushima Dai-ichi NPS, results of measurements are as follows;
One worker: At the level of exposure as 106.3 mSv, no risk of internal exposure and no medical treatment required.
Other workers: At the level of no risk for health but concrete numerical value is unknown

That is ridiculous! Were these workers not carrying dosimeters?

 

[rhody]

For a true appreciation: the scope of devastation caused by the tsunami,
covering almost 200 miles of the Japanese coast, take a look at http://www.abc.net.au/news/events/japan-quake-2011/beforeafter.htm":
and http://www.abc.net.au/news/events/japan-quake2011/beforeafter2.htm" , there are two parts...

Mouse over each photo (right to left and vice versa) before and after...

Rhody...

P.S. I just reviewed both pages, slowly... this is a sample of the havoc wrought by the waves.
Obviously the low lying areas took it the worst.

 

[PietKuip]

from Kyodo:

Electric Power Co. said Wednesday it has observed a neutron beam, a kind of radioactive ray, 13 times on the premises of the Fukushima Daiichi nuclear plant after it was crippled by the massive March 11 quake-tsunami disaster.

TEPCO, the operator of the nuclear plant, said the neutron beam measured about 1.5 kilometers southwest of the plant's No. 1 and 2 reactors over three days from March 13 and is equivalent to 0.01 to 0.02 microsieverts per hour and that this is not a dangerous level.

Not trying to flame the fire here. The rad levels are low and I'm hoping TEPCO continues to make progress controling the site but the neutron beam got me thinking about reactor integrity. Neutron beams are product of fission correct? Would this finding confirm reactor damage even if it's just a pin hole?

Are these fast neutrons or slow, moderated neutrons?

Slow neutrons do not carry significant energy, it is not really ionizing radiation, microSieverts does not seem an adequate measure for a flux of thermal neutrons.

So I conclude that these are fast neutrons. They do not need holes. Neutrons are not shielded by lead or steel.

One would expect some delayed neutrons from fission products, but neutron decays have short half lives. Can this level of neutrons be due to delayed neutrons? I suppose there is always some fission too, far below levels for criticality.

 

[jensjakob]

163.000 becquerels in soil northwest of Fukushima NPP:
http://www3.nhk.or.jp/daily/english/23_28.html

That is quite bad.?

 

[83729780]

http://en.wikipedia.org/wiki/Solubility" degree C is 60g/100 liters or 600g per m3 of water
(or about 40g/100 l at room temperature thus we need to evaporate 90% of seawater for
crystallization to take place at room temp)

Therefore, to have a homogeneous solution of salty coolant we need:
21216/0.6 = 35360m3 of water

Does the addition of boron to the coolant water significantly affect NaCl solubility?

 

[Borek]

Does the addition of boron to the coolant water significantly affect NaCl solubility?

Most likely not. But i am just guessing. There is no obvious reason (like a common ion or possible precipitate) and usually there are no significant effects till concentrations get really high, much closer to saturated solutions (and we are far from that with sea water).

 

[Bob S]

from Kyodo:

Electric Power Co. said Wednesday it has observed a neutron beam, a kind of radioactive ray, 13 times on the premises of the Fukushima Daiichi nuclear plant after it was crippled by the massive March 11 quake-tsunami disaster.

TEPCO, the operator of the nuclear plant, said the neutron beam measured about 1.5 kilometers southwest of the plant's No. 1 and 2 reactors over three days from March 13 and is equivalent to 0.01 to 0.02 microsieverts per hour and that this is not a dangerous level.

http://search.japantimes.co.jp/cgi-bin/nn20110324a6.html

Hard to believe. Where would the neutrons come from if the reactors are off? The nuclear collision length for high energy neutrons is about 60 grams per cm²; 1.5 km of air is about 180 grams per cm². This does not include any shielding like the reactor pressure vessel, and concrete shield wall. Below ≈100 KeV, the neutron scattering (and thermalization) increases dramatically. The only neutron sources in the buildings are probably PuBe, PoBe, and AmBe (americium-beryllium) neutron calibration sources for radiation detector calibration.

Focusing neutrons is like herding cats; 1/R² at 1.5 km is huge.

Bob S

 

[jensjakob]

Images from inside the Fukushima controlroom - after the Tsunami:
http://ekstrabladet.dk/nyheder/krigogkatastrofer/article1524724.ece

 

[curious11]

Hard to believe. Where would the neutrons come from if the reactors are off? The nuclear collision length for high energy neutrons is about 60 grams per cm²; 1.5 km of air is about 180 grams per cm². This does not include any shielding like the reactor pressure vessel, and concrete shield wall. Below ≈100 KeV, the neutron scattering (and thermalization) increases dramatically. The only neutron sources in the buildings are probably PuBe, Po,Be, and AmBe (americium-beryllium) neutron calibration sources for radiation detector calibration.

Focusing neutrons is like herding cats; 1/R² at 1.5 km is huge.

Bob S

Perhaps the sources were more local ? but I guess if this was the case they would be less likely to emit a focussed beam?

 

[Arcer]

Puzzling that there's plenty of damage as evidence of explosions and even possibly an earthquake but so far not much to say there's been tsunami water inside the main area of the site, that is the area to the west of the long turbine generator buildings and yet the tsunami is claimed to have been 10 metres and even 14 metres high - the height of say a 3 to 5 storey building - and if it was like the tsunami in other places it would be carrying tonnes and tonnes of debris along with it.

Looking at the close ups of the building surfaces there's no staining or anything. The water must have been very clean.

 

[jensjakob]

More images:
http://ekstrabladet.dk/template/v3-0/direct/article/picProxy.jsp?url=http://multimedia.ekstrabladet.dk/archive/00647/Japan_Earthquake_647291o.jpg&iw=925&ih=646&secid=1250&cbw=1210&cbh=818

 

[Borek]

if it was like the tsunami in other places it would be carrying tonnes and tonnes of debris along with it.

Not necessarily. At the coast - where the plant is located - water is clean, it collects debris as it flows over the land. Debris can be also left when water goes back to the sea, but there is an elevated land behind the NPP - so there was no water getting back through the plant area.

 

[jensjakob]

More images from the work @ Fukushima:
http://www.b.dk/billedeserier/her-arbejder-de-mod-tiden-paa-fukushima

@Arcer: Take a look at some of the early pictures, you will see cars, containers and other large items swept as debris against the earth-berm. QUite powerfull it must have been

 

[PietKuip]

from Kyodo:

TEPCO, the operator of the nuclear plant, said the neutron beam measured about 1.5 kilometers southwest of the plant's No. 1 and 2 reactors over three days from March 13 and is equivalent to 0.01 to 0.02 microsieverts per hour and that this is not a dangerous level

I now looked at the logs on http://www.tepco.co.jp/en/nu/monitoring/

In the recent logs I can only find entries that the neutron signal is "under 0.01 μSv/h".

In the March 13 logs, it says mostly "under 0.001μSv/h" at the main gate, but sometimes "under 0.002".

Tepco has a weird way of communicating their data.

PS: http://www.tepco.co.jp/en/nu/monitoring/11031401a.pdf gives some readings as "under 0μSv/h". Idiots.

 

[83729780]

Today is the 11th day since sea water injection started and let's assume another two days
till pumps start working

--> 13 x 24hours x 2m3/hour x 34kg = 21216 kg salt

another estimate:

Richard T. Lahey Jr., who was General Electric’s chief of safety research for boiling-water reactors when the company installed them at the Fukushima Daiichi plant, said that as seawater was pumped into the reactors and boiled away, it left more and more salt behind. He estimates that 57,000 pounds of salt have accumulated in Reactor No. 1 and 99,000 pounds apiece in Reactors No. 2 and 3, which are larger.

http://www.nytimes.com/2011/03/24/world/asia/24nuclear.html?_r=1&hp
press date 24/03

 

[jlduh]

The TEPCO document on tsunamis that i posted confirm that the plant itself is built on a platform which is 10 to 13 meters higher than sea level. So in case of a wave whose height is around 14 meters, only the very top of the tsunami (which is not -relatively- a very big amount of water: 1 to 4 meters ) have entered the buildings location. This was enough unfortunately to damage the diesel generators which are in the first line (close to the sea). But it's not a so big amount for the buildings because most of the energy of the wave has been dissipated hitting the 10 to 13 meters height of the platform.

To come back on the subject of the neutron beams (up to 1,5 kms long) that tepco reported, can somebody tell me how this phenomenon was detected? Is it something you can see visually or was it through detectors?

thanks.

 

[jensjakob]

another estimate:



http://www.nytimes.com/2011/03/24/world/asia/24nuclear.html?_r=1&hp
press date 24/03

And - scary to read that cooling pumps at #5 has stopped...

 

[Arcer]

Not necessarily. At the coast - where the plant is located - water is clean, it collects debris as it flows over the land. Debris can be also left when water goes back to the sea, but there is an elevated land behind the NPP - so there was no water getting back through the plant area.

Thanks for your response.

There's plenty of damage shown as the tsunami flowed over the constructions and surfaces (extending over about 100 metes) to the east of the long turbine generator buildings back to the breakwater/harbour/coast - that's evident from the satellite images. Maybe that debris is partly piled up against the east face of those turbine buildings. Maybe some of it went out with the tsunami.

Even so I would have expected a 10 - 14 metre tsunami to take a lot of the debris around the north and south ends of the turbine buildings and between those buildings and some of it to be deposited to the west and also deposited to the west as it went back out. If it was 10 to 14 metres high I would have expected far more damage to the low level buildings to the west of the turbine buildings and there's little or none although there seemed to be some cars moved around from the satellite images.

As far as I'm aware the entire plant area is pretty flat and the only elevated land is about 100 metres to the west of the turbine buildings and that is about 60 metres to the west of the reactor buildings - the embankments for that elevated land are evident from the satellite images and are shown on the image below.

Those embankments would act as a barrier to further inland flow of the tsunami but wouldn't have stopped the tsunami getting back out through the plant area.

http://ekstrabladet.dk/template/v3-0/direct/article/picProxy.jsp?url=http://multimedia.ekstrabladet.dk/archive/00647/Japan_Earthquake_647291o.jpg&iw=925&ih=646&secid=1250&cbw=1210&cbh=818

On that image (or any other Fukushima image for that matter) where's the staining from a 10 - 14 metre high tsunami on the walls that even clean water would show just carrying a bit of surface debris and dirt just from the roads. It's just a bit puzzling that apart from it totalling the entire power plant operation so far the images show relatively little sign of such a huge tsunami at least to the west of the site.

edit: jlduh's response above clarifies that there's a change in level on the site near the line of turbine buildings.