Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[MadderDoc]

I have been working to understand the "real world levels and operator logs" since they were first published. I believe the operator logs are accurate but incomplete.<..>

That may well be, but the assumption that some observations are missing does not allow the model to disregard existing observations. According to the operator log, the operator observed IC to be operational at about 18:18-18:25 on March 11th, and again at 21:30, while the model assumes the function of IC to have been lost at SBO, at about 16:00 on March the 11th,

As to levels, we have previously discussed the level instrument reference leg and condensing chamber designed to keep the reference leg full. Once containment temperatures exceeded the boiling point the level of the reference legs would have been unknown. <..>

Yes I understand that, but the model we are talking about does not have the PCV temperature exceeding that boiling point until about 9-12 hours after those water level data readings which the model needs to dismiss.

 

[~kujala~]

starts to brake into peaces

Sorry, I meant: break into pieces...

 

[jmelson]

There was some discussion of the CAMS units at Fukushima a while ago. I am at the Texas A&M Cyclotron right now, and they have a CAMS here. I looked for the manual but could not find it in the repository for manuals. But, I did get a good look at the unit. It is about a 12 x 12 x 6" box, with a paper filter and a small Silicon detector. I think the vacuum pump to suck air through the filter is external. The filter paper is on a roll and is advanced at regular intervals. So, this unit requires maintenance to replace the filter paper every so many days. Also, if it is exposed to steam or high amounts of water vapor, the filter paper is likely to disintegrate like wet toilet paper, and make the unit stop functioning.

Jon

 

[marsupio]

hello,

I personnally want to adress great thanks to the chemist who create the ' gum' that fill the hole of daichii fukushima (the leak were 3 months )

now the only way is to learn to live with a scrappet of a maximum of nuclear power plant.

best regards

 

[Bodge]

Looks like, in the early days of the crisis, significant quantities of U-239 were able to migrate at least 35km from FUK-1.

https://www.physicsforums.com/showpost.php?p=3462692&postcount=221

 

[etudiant]

Looks like, in the early days of the crisis, significant quantities of U-239 were able to migrate at least 35km from FUK-1.

https://www.physicsforums.com/showpost.php?p=3462692&postcount=221

Not good news.
Does that not imply burning fuel, or at least boiling uranium? It seems plausible given the reality of several meltdowns, but it also implies a much dirtier site if there are uranium and neptunium deposits outside of the containments.

 

[joewein]

Looks like, in the early days of the crisis, significant quantities of U-239 were able to migrate at least 35km from FUK-1.

https://www.physicsforums.com/showpost.php?p=3462692&postcount=221

I couldn't see exactly when the samples were taken, but the rough parity between iodine and cesium radiation levels in those figures suggests it was perhaps around the second week of April, based on published isotope distribution in Tokyo drinking water at the time. That would be roughly 10 half lives of Np-239, or three orders of magnitude of decay from scram levels. That would move it from several 10^2 Bq/kg to several 10^5 Bq/kg at release time, if the release was around the initial meltdown events. Given that Np-239 decays to Pu-239 with 24,000 years half life, that's certainly not good.

What puzzles me though is that uranium, neptunium and plutonium are not particularly volatile, especially in oxide form. They do not readily vaporize, unless there's extreme heat or a massive explosion. With the normal vent path, the gasses from the core would first be scrubbed through the suppression chamber water. I would imagine that most of these heavy oxides that make it into some kind of aerosol during a fuel rod fire or meltdown would be trapped at that stage.

We've had some debate in the unit 3 explosion thread about a leak from the unit 3 containment through the lid into the 5F/RF space during the explosion there. That is more like the kind of vent path that would be necessary in my opinion to get such high doses of heavy oxides into the plume.

On the other hand, given that the Np-239 should have decayed to Pu-239 by now, which is not going to disappear any time soon, I would like to see the actinide contamination levels to the NW of F-1 confirmed before we speculate too much.

 

[zapperzero]

What puzzles me though is that uranium, neptunium and plutonium are not particularly volatile, especially in oxide form. They do not readily vaporize, unless there's extreme heat or a massive explosion.

Indirect evidence for recriticality keeps mounting, iow?

 

[jim hardy]

""I would imagine that most of these heavy oxides that make it into some kind of aerosol during a fuel rod fire or meltdown would be trapped at that stage.""

there was venting and water injection in those early days.

My guess would be aerosols, and responsible for those small neutron readings at main gate too.

were levels "Significant" or detectaible ? I can't make out the numbers in that link.

old jim

 

[joewein]

Indirect evidence for recriticality keeps mounting, iow?

I'd be more inclined to believe in recriticality if iodine levels exceeded cesium levels again and sampling around the site perimeter spiked, which it hasn't really since the end of March:

http://fukushima.grs.de/sites/default/files/Entwicklung_ODL.jpg"

http://fukushima.grs.de/sites/default/files/Messpunkte_Reaktorgelaende.jpg"

 

[joewein]

were levels "Significant" or detectaible ? I can't make out the numbers in that link.

From http://user.ecc.u-tokyo.ac.jp/~cshozu/images/seminar.pdf

Enlarged shots from the PDF attched.

 

[zapperzero]

I'd be more inclined to believe in recriticality if iodine levels exceeded cesium levels again and sampling around the site perimeter spiked, which it hasn't really since the end of March

I apologize for the sloppiness, I meant recriticality then, in the first few days, not now.

 

[tsutsuji]

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110821_01-e.pdf SFP4 desalting facility started at 11:34 AM, August 20.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110820_02-e.pdf this is SARRY line B decontamination factors. [What happened with line A ?]

http://mainichi.jp/select/jiken/news/20110821ddm008040068000c.html With a 25 m³/hour flow, SARRY will achieve removing all the water stored in one of the waste treatment facility's buildings [which one?] in nine days' time.

http://www.asahi.com/special/10005/TKY201108210168.html Two new reverse osmosis equipments have been started at the desalination facility on 21 August. They are increasing the facility's capacity from 50 to 70 tons per hour. It was said that this increase goes together with the decontamination facility's flow increase from 45 to 70 tons per hour permitted by the start of SARRY.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110821/0700_1gouki.html All the thermometers at unit 1 are now below 100°C.

http://www.nikkei.com/news/category...E3E2E3938DE0E3E2EAE0E2E3E39797EAE2E2E2;at=ALL Tepco is planning to switch to an alternative injection method using the reactor spray line at unit 3. The switching procedure will be tested at unit 5 on 22 August. Implementation at unit 3 will ensue later this week.

 

[zapperzero]

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110821_01-e.pdf SFP4 desalting facility started at 11:34 AM, August 20.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110820_02-e.pdf this is SARRY line B decontamination factors. [What happened with line A ?]

http://mainichi.jp/select/jiken/news/20110821ddm008040068000c.html With a 25 m³/hour flow, SARRY will achieve removing all the water stored in one of the waste treatment facility's buildings [which one?] in nine days' time.

http://www.asahi.com/special/10005/TKY201108210168.html Two new reverse osmosis equipments have been started at the desalination facility on 21 August. They are increasing the facility's capacity from 50 to 70 tons per hour. It was said that this increase goes together with the decontamination facility's flow increase from 45 to 70 tons per hour permitted by the start of SARRY.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110821/0700_1gouki.html All the thermometers at unit 1 are now below 100°C.

Some good news for a change. Thank you.

 

[joewein]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110821/0700_1gouki.html All the thermometers at unit 1 are now below 100°C.

Sounds good, but it would have a lot more meaning if we knew

a) that the thermocouples at the bottom of the RPV were still magnetically (?) attached to it and working and

b) if the fuel was known to be inside the RPV and not dripped onto a concrete surface lower down without any thermometers.

I guess Tepco will still consider this "cold shutdown achieved", even if the corium (wherever it is) was still liquid inside.

 

[zapperzero]

Sounds good, but it would have a lot more meaning if we knew

a) that the thermocouples at the bottom of the RPV were still magnetically (?) attached to it and working and

b) if the fuel was known to be inside the RPV and not dripped onto a concrete surface lower down without any thermometers.

I guess Tepco will still consider this "cold shutdown achieved", even if the corium (wherever it is) was still liquid inside.

Maybe we should write a petition for them to try and get images from the RPV already :P

 

[Bodge]

Atmospheric chemists at UC San Diego have analysed anomalous findings of radioactive Sulfur-35 at Scripps California.

Seawater injection into the cores began on http://www.tepco.co.jp/en/press/corp-com/release/11031301-e.html".

Natural Cl-35 in the water gained a neutron and lost a proton to become S-35.

The calculations done by UCSD suggest a powerful neutron flux during the time of seawater cooling.

links http://www.pnas.org/content/early/2011/08/11/1109449108.abstract"

Lead Author Mark Thiemens, Dean of the Division of Physical Sciences at UC San Diego:

"We were able to say how many neutrons were leaking out of that core when it was exposed."

Using a model based on NOAA's observations of atmospheric conditions the team determined the path air took on its way to the pier over the preceding 10 days and found that it led back to Fukushima.

Then they calculated how much radiation must have been released. "You know how much seawater they used, how far neutrons will penetrate into the seawater and the size of the chloride ion. From that you can calculate how many neutrons must have reacted with chlorine to make radioactive sulfur," said Antra Priyadarshi, a post-doctoral researcher in Thiemens' lab and first author of the paper.

After accounting for losses along the way as the sulfate particles fell into the ocean, decayed, or eddied away from the stream of air heading toward California, the researchers calculated that 400 billion neutrons were released per square meter surface of the cooling pools, between March 13, when the seawater pumping operation began, and March 20, 2011.

see http://www.sciencedaily.com/releases/2011/08/110815152027.htm
and http://www.fairewinds.com/content/new-data-supports-previous-fairewinds-analysis-contamination-spreads-japan-and-worldwide Remember the discovery of huge levels of Cl-38 that were found and then later denied?
How about the "13 neutron beams"?
One thing is now CERTAIN - there were significant nuclear excursions long after reactor SCRAM.

This is the sort of detective work that wouldn't be necessary if certain informed/industry sources told us the truth from the start.

 

[NUCENG]

Maybe we should write a petition for them to try and get images from the RPV already :P

As this is a Physics Forum, let's consider that. Do you mean images of the RPV or images in the RPV? Are you talking about a boroscope -type examination through piping or a drywell entry with robots or humans? What are the risks? What are the benefits- what would we learn? Based on what we might learn, what would the Japaneses be able to do differently? Compared to cooling the reactors and containments, cleaning up the site, and building the enclosures what would make this a higher priority that the current road map steps?

I see the emoticon, so perhaps you were not serious, or were trying to point out that joewein is once again tossing out the silver lining of temperatures dropping below 100 degC looking for the dark cloud that is out there someplace?

 

[etudiant]

Atmospheric chemists at UC San Diego have analysed anomalous findings of radioactive Sulfur-35 at Scripps California.



After accounting for losses along the way as the sulfate particles fell into the ocean, decayed, or eddied away from the stream of air heading toward California, the researchers calculated that 400 billion neutrons were released per square meter surface of the cooling pools, between March 13, when the seawater pumping operation began, and March 20, 2011.



Remember the discovery of huge levels of Cl-38 that were found and then later denied?
How about the "13 neutron beams"?
One thing is now CERTAIN - there were significant nuclear excursions long after reactor SCRAM.

This is the sort of detective work that wouldn't be necessary if certain informed/industry sources told us the truth from the start.

Could someone help put these numbers into perspective?
A mole of material, (about 238gm of Uranium), has 6x10**23rd molecules. So a flux of 4x10**11 neutrons/square meter over a week roughly equates to the decay of maybe 2x10**-10 gms of uranium. This does not seem that large. Is this nevertheless inconsistent with normal decay processes in a seriously damaged scrammed reactor?

 

[jim hardy]

Bodge wrote:

"How about the "13 neutron beams"?
One thing is now CERTAIN - there were significant nuclear excursions long after reactor SCRAM."

the 13 "neutron beams" was an unfortunate translation. On another thread we had a contributor from Tokyo who translated the article, 'beam' had meaning closer to 'individual ray' or particle. Word "Beam" in English immediately makes one think of an intense searchlight beam, what they had was way more feeble.
So we took the reports to be from low level indication on the neutron monitors at plant gate, which was later corroborated by logsheets. At first i figured it was somebody walking or driving by in contaminated boots or vehicle, but the times pretty well coincided with venting so i changed my opinion to airborne 'aerosols' from water injection and venting. Of course that's all speculation on my part but it sort of fits with recent find of hotspots at bottom of stack and in vent pipe...

Let's wait and see what other indications show up. From that article,

the researchers calculated that 400 billion neutrons were released per square meter surface of the cooling pools, between March 13, when the seawater pumping operation began, and March 20, 2011

That's an unusual way to describe a neutron flux activation so i wonder if it too lost something in translation into laypeople-speak? 400 billion per square meter is 40 million per sq centimeter if my arithmetic is good,,,,
and only 4E7 n/cm^2 is a low neutron flux even if it came all in one second let alone spread over a whole week. A significant nuclear excursion should produce a million times that in less than a second - perhaps more details will appear.

In my book recriticality is niether proven or disproven yet. That it would be exciting should not colour our analysis.

I do second the motion for photo of RPV's, especially around their upper heads.

Did they ever get vessel level and pressure instruments hooked up on units 2&3 like they did on 1?
[image] http://www.tepco.co.jp/en/news/110311/images/110604_10.jpg [/image]
old jim

 

[Bodge]

...Remember the discovery of huge levels of Cl-38 that were found and then later denied?

http://www.ieer.org/comments/Cause_of_high_Cl-38_Radioactivity20110330.pdf

The author calculated neutron flux from spontanoeus fission of actinides in a core melt and found that it was not enough to explain the high levels of Cl-38.

I know that TEPCO later changed their minds on the detection itself, but it makes you wonder.

 

[Bodge]

If I understand correctly, they are speaking of the number of neutrons that escaped from the surface of the storage pools, which are above the reactor cores.

4E7 n/cm^2 was not the flux, it was what escaped the pools.

That's an unusual way to describe a neutron flux activation so i wonder if it too lost something in translation into laypeople-speak? 400 billion per square meter is 40 million per sq centimeter if my arithmetic is good,,,,
and only 4E7 n/cm^2 is a low neutron flux even if it came all in one second let alone spread over a whole week. A significant nuclear excursion should produce a million times that in less than a second - perhaps more details will appear.

From the paper's abstract: http://www.pnas.org/content/early/2011/08/11/1109449108.abstract

.."we show that nearly 4 × 10^11 neutrons per m2 leaked at the Fukushima nuclear power plant before March 20, 2011."

 

[etudiant]

If I understand correctly, they are speaking of the number of neutrons that escaped from the surface of the storage pools, which are above the reactor cores.

4E7 n/cm^2 was not the flux, it was what escaped the pools.


From the paper's abstract: http://www.pnas.org/content/early/2011/08/11/1109449108.abstract

.."we show that nearly 4 × 10^11 neutrons per m2 leaked at the Fukushima nuclear power plant before March 20, 2011."

It would help if someone versed in these kinds of measurements would interpret these results. The terminology is less than clear.
The element detected was sulfur, formed from the chlorine held in the sea water salt. That transmutation takes place in the water and involves the neutrons from the reactor cores.
That suggests the neutron flux is not measuring the number escaping the pools, as that is a pretty meaningless quantity which has no relevance to the sulfur production recorded. So are they talking about neutron flux per square meter of core area?

 

[Bodge]

Somebody with access to the full article should take a look.

 

[jim hardy]

http://www.ieer.org/comments/Cause_of_high_Cl-38_Radioactivity20110330.pdf

The author calculated neutron flux from spontanoeus fission of actinides in a core melt and found that it was not enough to explain the high levels of Cl-38.

Some of us chased that Cl38 reading on another forum in March. What i remember is this:

If you take Dr Veress's equation for flux from page 5 of that article;
=5.241510/(1−−38)

and plug in his value for (lambda 38) from page 4;
λ38=0.00031021 s-1

and plug in the completely unfounded number of 1 second for irradiation time T

you get the worrisome result of about 1.7E14
which is quite reasonable for neutron flux in the reactor core during a 1 second excursion to 200% reactor power
were there reports of a steam explosion near the date of that measurement (25 March) it'd be a strong indicator of recriticality about that time.

In chasing that one I was told by a radiochemist that because Cl38's spectrum closely resembles some other nuclides it is easy to mis-report its pesence. Myself, I have accepted the official explanation that the Cl38 reading was an error.

Once again, not quite enough info for a layman to conclude anything. Even Dr Veress is not certain.

If you find reports of Cl38 closer to 14 March please post links.
old jim

 

[joewein]

The Swedes built a facility called FILTRA at their Barsebäck two-unit BWR site in the early 1980's. Here's a really thorough and well-written progress report of the project that resulted into a 10 000 m3 gravel bed being built next to the the units. That might be one approach to improve the capacity of old containments; however, it won't remove the problems related to preventing core-concrete interactions if a molten core falls to the bottom of the containment.

EDIT: Photograph of the Barsebäck site, with the FILTRA facility on the foreground.

Tepco seems to say, by contrast, that no filtration beyond the limited scrubbing by venting into the suppression pool water was necessary (http://www.tepco.co.jp/en/news/topics/11081601-e.html"):

Corrections and Clarification of a news report program, "ETV Special" by NHK, broadcasted on August 14

August 16, 2011
Tokyo Electric Power Company
NHK TV program regarding Fukushima Daiichi Nuclear Power Station reported contents that are incorrect and could cause misunderstandings. We hereby provide facts below.
(...)
3. Claim on the PCV ventilation has no filtration
In the program, it was mentioned several times that there were no filters in the primary containment vessel ventilation line. However, boiling water reactors that we operate use "wetwell vent", which has scrubbing effect to mitigate emission of radioactive materials at the comparative level to the filters. That is to say, in principle, our venting procedure uses the water in the suppression chamber as filteration and we have prepared and added the necessary equipment and procedures for accident management measures.

In other words, they claim pool water scrubbing is good as proper filters, no need to spend money on them.

 

[zapperzero]

As this is a Physics Forum, let's consider that. Do you mean images of the RPV or images in the RPV? Are you talking about a boroscope -type examination through piping or a drywell entry with robots or humans? What are the risks? What are the benefits- what would we learn? Based on what we might learn, what would the Japaneses be able to do differently? Compared to cooling the reactors and containments, cleaning up the site, and building the enclosures what would make this a higher priority that the current road map steps?

I see the emoticon, so perhaps you were not serious, or were trying to point out that joewein is once again tossing out the silver lining of temperatures dropping below 100 degC looking for the dark cloud that is out there someplace?

I was not serious in the sense that I do not believe that a petition would do anything.
Other than that, I am quite serious wrt imaging and data collection in general being a very high priority still.

I think the questions that need to be answered are:

1. is there corium in the RPVs? How much? (borescope)
2. is there corium on the drywell floors? How much? If so, is it still attacking the concrete? (robots, and underwater robots at that)
3. is there ongoing criticality in the corium?

Now, a list of what could be done differently, based on what we may learn from an answer to question
1. injection of water to the RPVs could be stopped or massively reduced.
2. an alternative cooling strategy may be possible/desirable. Additional containment measures may be needed.
3. if there is still a reaction going on somewhere, trying to filter the water in the basement is basically a fool's errand, no? Stopping any recriticality should also ease cooling. I took a look at the TEPCO webcam earlier this morning. 1F3 is still making steam.

Now for the risks
- borescope expedition may block up piping that could be useful later
- time, money, specialist equipment, man-hours, health of workers may be expended for no gain

 

[zapperzero]

Tepco seems to say, by contrast, that no filtration beyond the limited scrubbing by venting into the suppression pool water was necessary (http://www.tepco.co.jp/en/news/topics/11081601-e.html"):

In other words, they claim pool water scrubbing is good as proper filters, no need to spend money on them.

Well TEPCO's claim is true - and disingenuous, I believe. Normally, venting is done via the suppression pool. In major emergencies, iirc, venting is performed directly to the atmosphere via something called a hardened vent.

That lost TEPCO precious hours while they were trying to decide if possibly staving off meltdown was worth certainly irradiating the countryside. Frying Naoto Kan, who was coming in via helicopter, may or may not have been an additional concern.

 

[tsutsuji]

Sounds good, but it would have a lot more meaning if we knew

a) that the thermocouples at the bottom of the RPV were still magnetically (?) attached to it and working and

b) if the fuel was known to be inside the RPV and not dripped onto a concrete surface lower down without any thermometers.

I guess Tepco will still consider this "cold shutdown achieved", even if the corium (wherever it is) was still liquid inside.

The Nikkei said some prudent words on this topic on 20 August:

http://www.nikkei.com/news/editoria...E38297EAE2E2E2;n=96948D819A938D96E38D8D8D8D8D Also, it is not exactly known where the melted nuclear fuel fell. If it has fallen down from the reactor pressure vessel, as many experts point out, even if that container's temperature is less than 100 degrees, it is a far cry from saying it is safe.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110823/index.html It was found last month that a company commissioned by Kyushu Electric had entered a wrong data in the earthquake resistance assessment of Genkai NPP unit 3. The NISA then ordered all NPP operators commissioning the same company to check their data. Then Kansai Electric found the same data problem at its Mihama unit 3 and 4 reactors, although they are commissioning a different company. Now the NISA is instructing all NPP operators in Japan to check their data, regardless which company they commissioned. The NISA confesses that it "excessively held the prejudice" that the problem was circumscribed to only one company. This problem might create delays in the "stress tests" nuclear plants in periodic inspection must undergo before restarting.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110823/0445_hoshutsuryo.html The NISA is revising its estimate of the cumulated iodine 131 and cesium 137 radiation released from Fukushima Daiichi between 12 March and 5 April from 63 E16 Bq to 57 E16 Bq. It is based on newly obtained data, such as monitoring post data and air analysis data. The peak is believed to have occurred after the units 2 and 4 explosions, from 1:00 to 5:00 PM on 15 March. As was found in the previous estimate, the peak amounts for 40% of the release. The estimate was made by the Japan Atomic Energy Agency for the NISA.

 

[NUCENG]

It would help if someone versed in these kinds of measurements would interpret these results. The terminology is less than clear.
The element detected was sulfur, formed from the chlorine held in the sea water salt. That transmutation takes place in the water and involves the neutrons from the reactor cores.
That suggests the neutron flux is not measuring the number escaping the pools, as that is a pretty meaningless quantity which has no relevance to the sulfur production recorded. So are they talking about neutron flux per square meter of core area?

O.7 % of the radioactive sulfates from Fukushima reached the pier in San Diego? So why didn't similar percentages of I131, Cs-137, and noble gases, etc. make the same trip? Why is S-35 so efficient?

1501 atoms of S-35 per cubic meter measured in 4 days. Let me assume that they mean a peak of 1501 Bq/m^2 was detected during a 4 day period. And they had never seen a peak at that pier over 950 Bq/m^2 before that. So there is a background level of Cl-35 from activation of Argon in the upper atmosphere in that measurement that needs to be considered. That means a lower Fukushima source number.

Check this out:

http://www.agu.org/pubs/crossref/2011/2011GL047469.shtml

The graph shows 1600 atoms of radioactive sulfer in sulfate per cubic meter in Antarctica in January 2010 with no help from Fukushima. Same authors.

The moving box model used is also interesting. I don't know from the description if it accounts for dispersion and dilution. If their model assumes transport via the jetstream it appears that numbers like 0.7% or a concentration at Fukushima over normal background at a factor of 365, it seems that dispersion and dilution are almost non-existent. Typical US radiological consequences have dispersion factors of 10E-4 of 10E-5 for elevated releases within hundreds of yards and we are talking about 5000 miles. Their previous work with cosmic sourced S-35 was based on a uniform production of S-35 and that is different from a point source like Fukushima.

There data shows a peak they can't ex[plain from their experience. They postulate that it is
caused by Cl-35 (n,p) reactions, but other than the time coincidence I don't see why they rule out cosmic sources. I would like to see if they answer these questions in their full article, but NAS wants to get paid $10 more than my curiosity extends.

I am not ready to say they are wrong or right. Their abstracts are more confusing than informative. Just between you and me, when I see that Arnie Gunderson thinks it supports his theories, I tend to be a little bit skeptical.