Nuclear Open Thread

Fukushima Technical Discussion Open Thread

It was suggested in a comment — and I agree — that the previous open threads on the Fukushima Daiichi Nuclear Accident were becoming difficult to read, because they are such a mixture of technical details and philosophical discourse. That is, it’s generally a bad idea to cater to two different audiences in one comment thread. So, I will split them up.

Please restrict all discussion here to technical information, analysis, criticisms and questions on FD — no philosophising or excursions into whether nuclear power is ‘good’ or ‘bad’ or the implications of FD for the future of nuclear power (except for new technical developments, e.g. safety standards), etc. You may impart your deep wisdom on how the world should work on the other open thread I’m about to open.

Besides the above guidelines, the other rules of the Open Threads on BNC apply. Read here for details.

To kick off discussion, below is the latest FEPC status report (I’ll update this as new reports come in). You will also be interested in:

— JAIF Updates #35 and #36

NISA Major Parameters 0600 March 29

NISA Summary Conditions 0600 March 29


  • Radiation Levels
    • At 11:45PM (JST) on March 28, TEPCO announced that plutonium 238, 239 and 240 were detected in the soil sampled on March 21st and 22nd at five spots in Fukushima Daiichi Nuclear Power Station. Concentration of detected plutonium 238, 239 and 240 are the same level of the fallout observed in Japan at the atmospheric nuclear tests in the past and poses no major impact on human health.
    • At 6:30PM on March 29, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 177 micro Sv/hour.
    • At 6:30PM on March 29, radiation level at west gate (approximately 3,609 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 120.2 micro Sv/hour.
    • Measurement results of environmental radioactivity level around Fukushima Nuclear Power Station announced at 7:00PM on March 29 are shown in the attached PDF file. English version is available at:
    • For comparison, a human receives 2,400 micro Sv per year from natural radiation in the form of sunlight, radon, and other sources. One chest CT scan generates 6,900 micro Sv per scan.
  • Fukushima Daiichi Unit 1 reactor
    • At 1:00PM on March 29, pressure inside the reactor core: 0.371MPa.
    • At 1:00PM on March 29, water level inside the reactor core: 1.65 meters below the top of the fuel rods.
    • At 1:00PM on March 29, pressure inside the primary containment vessel: 0.265MPaabs.
    • At 1:00PM on March 29, the temperature of the reactor vessel measured at the water supply nozzle: 570.9 degrees Fahrenheit
    • As of 3:00PM on March 29, transferring the water found at the turbine building to the condenser continues.
    • As of 4:00PM on March 29, the injection of freshwater into the reactor core continues.
  • Fukushima Daiichi Unit 2 reactor
    • At 1:00PM on March 29, the temperature of the spent fuel pool: 114.8 degrees Fahrenheit.
    • At 1:00PM on March 29, pressure inside the reactor core: -0.025MPa.
    • At 1:00PM on March 29, water level inside the reactor core: 1.5 meters below the top of the fuel rods.
    • At 1:00PM on March 29, pressure inside the primary containment vessel: 0.1MPaabs.
    • As of 4:00PM on March 29, the injection of freshwater into the reactor core continues.
    • As of 7:00PM on March 29, approximately 96 tons of water in total has been injected into the spent fuel storage pool.
  • Fukushima Daiichi Unit 3 reactor
    • At 12:00PM on March 29, pressure inside the reactor core: 0.029MPa.
    • At 12:00PM on March 29, water level inside the reactor core: 1.85 meters below the top of the fuel rods.
    • At 12:00PM on March 29, pressure inside the primary containment vessel: 0.1075MPaabs.
    • At 2:17PM on March 29, TEPCO began to shoot freshwater aimed at the spent fuel pool, with a specialized vehicle normally used for pumping concrete, until 6:18PM (approximately 100 tons in total).
    • As of 4:00PM on March 29, the injection of freshwater into the reactor core continues.
    • As of 7:00PM on March 29, approximately 4,697 tons of water in total has been shot to the spent fuel storage pool.
  • Fukushima Daiichi Unit 4 reactor
    • At 11:50AM on March 29, lighting was restored in the Central Control Room.
    • As of 7:00PM on March 29, approximately 960 tons of water in total has been shot to the spent fuel storage pool.
  • Fukushima Daiichi Unit 5 reactor
    • At 2:00PM on March 29, the temperature of the spent fuel pool: 101.5 degrees Fahrenheit.
  • Fukushima Daiichi Unit 6 reactor
    • At 2:00PM on March 29, the temperature of the spent fuel pool: 70.7 degrees Fahrenheit.
  • Fukushima Daiichi Common Spent Fuel Pool
    • At 3:10PM on March 28, the temperature of the spent fuel pool: 95 degrees Fahrenheit.
    • As of 7:00PM on March 29, approximately 130 tons of water in total has been injected to the spent fuel storage pool.

By Barry Brook

Barry Brook is an ARC Laureate Fellow and Chair of Environmental Sustainability at the University of Tasmania. He researches global change, ecology and energy.

368 replies on “Fukushima Technical Discussion Open Thread”

Latest from TEPCO Washington:
TEPCO Earthquake Information Update on March 28: Detection of Pu in the soil in Fukushima Daiichi NPS

On March 28th, TEPCO announced the result of analysis of plutonium contained in the soil collected on March 21st and 22nd at the 5 spots in Fukushima Daiichi Nuclear Power Station (See Map 1 bellow). As a result, plutonium 238, 239 and 240 were detected as shown in the Table.

– The density of detected plutonium is equivalent to the fallout observed in Japan when atmospheric nuclear tests were conducted in the past.

– We assume the current reactor accident was a possible cause of plutonium detected from two samples out of five ((1) and (5)), considering their activity ratio of the plutonium isotopes.

– The density of detected plutonium is equivalent to the density in the soil under normal environmental conditions and therefore poses no major impact on human health. TEPCO strengthens environment monitoring inside the station and surrounding areas.

– We will conduct analysis of the three additional soil samples.

We will continue the radionuclide analysis contained in the soil at three points in the site (See Map 2 bellow).

Result of Pu measurement in the soil in Fukushima Daiichi Nuclear Power Plant
(Unit: Bq/kg・dry soil)* :MEXT environmental radiation database; 1978-2008 Density of detected Pu-238, Pu-239 and Pu-240 are within the same level of the fallout observed in Japan after the atmospheric nuclear test in the past. Activity ratio of Pu-238 detected in site field and solid waste storage against Pu-239 and Pu-240 are 2.0 and 0.94 respectively. They exceed activity ratio of 0.026 which resulted from the atmospheric nuclear test in the past, thus those Pus are considered to come from the recent incident.

At this moment the source of the plutonium is not identified. Uranium fuel installed in each unit contains 0 to 1% of plutonium.

Since uranium fuel produces plutonium through nuclear fission, we can not determine that the detected plutonium is from the MOX fuel at unit 3.

The detected density is considered to be within the variation range of the density found in the ordinary domestic soil.

For reference, measured density of Pu 239 and 240 in the soil from Fukushima prefecture this year was ND~0.21Bq/kg from 4 towns surrounding plants and 0.61 Bq/kg from Fukushima City.

Detected density of plutonium is within the same level of density in the normal environment. Therefore there will be no direct negative impact on worker’s health.

The nuclide of plutonium is alpha. It can be shielded by a paper and does not penetrate skin. Therefore, the effect of external exposure on human health will be negligible. However, if it is orally ingested, it poses risk of internal exposure. If we suppose oral intake of 1kg of sample soil which includes highest concentration of plutonium 239 measured this time, which equals 1.32Bq/kg・drysoil, the internal exposure is approximately 0.3 microSv. (1.32 x 2.5 x 10 E -4 = 0.00033 mSv = 0.3 microSv)


TEPCO Earthquake Information Update on March 29: Fukushima-Daiichi Tsunami Preparation

It is reported that TEPCO has downplayed tsunami threats. Also it is said that if TEPCO had taken account of Jogan earthquake (869 A.D.), TEPCO should have been able to avoid suffering from damage.

TEPCO’ s position (and facts) regarding our tsunami estimate/preparation are shown below:

– Based on the evaluation method by the Japan Society Civil Engineers, we voluntarily conducted an assessment regarding Tsunami of O.P. 5.1~5.7m.

– However, we haven’t anticipated an earthquake involving all regions from offshore Miyagi to Ibaraki simultaneously.

– The Headquarters for Earthquake Research Promotion is stating that “an earthquake involving all regions from offshore Miyagi to Ibaraki simultaneously” was beyond consideration.

– We acknowledge that at the joint working group for earthquake resistant engineering, there was a study to take account of Tsunami by Jogan earthquake and there were reports and presentations published.

– However, we understood that the study was not completed as a unified opinion and required further research. Even so, we paid attention to the study and from last year, we voluntarily began to conduct the investigation on the Tsunami sediments and publicized the results as a thesis.

– The magnitude of Tohoku- Pacific Ocean Earthquake by far exceeded that of Jogan earthquake of which there are various estimations regarding the scale.

– When TEPCO applied for the site permit of Fukushima Daiichi Nuclear Power Station, we assumed O.P. + 3.1m as the highest tide level taking Chili Earthquake in 1960 into consideration.

– Since the Tsunami analysis techniques have been developed, based on the evaluation by the Japan Society Civil Engineers, we predicted O.P + 5.4 to 5.7m assuming various earthquakes off the coasts of such as Sanriku and Fukushima (Keicho earthquake in 1611 was also taken into account). Based on this evaluation, we took safety measures such as elevating motors for pumping up seawater used for back-up diesel generators.

– The headquarters for Earthquake Research Promotion is stating that they had evaluated seismic motion and Tsunami in each specific area, and that however an earthquake involving all those regions simultaneously was beyond the scope of the assumption.

TEPCO Washington Office :202-457-0790
Kenji Matsuo, Director and General Manager
Yuichi Nagano, Deputy General Manager,
Masayuki Yamamoto, Manager, Nuclear Power Programs


* Barry, you calculate a dose for Pu-239 ingestion, but I believe Pu-238 is the most radiotoxic. Not that it matters much — the focus on plutonium is hugely overhyped. But it would be nice to see some calculations — I suspect the in-core radiotoxicity of Cs-137 alone exceeds all Pu isotopes.

I’ve found some dose factors here, but need to track down more of them:

* The dose rate in #2 turbine hall basement is reported as “>1,000 mSv/hr” (exceeded measurement limits); based on the activities reported below, it could be much higher. Fission product concentrations are between 25-60x higher in #2 turbine hall standing water than in #3, where the surface dose rate is 750 mSv/hr. (It’s been reported that the I-134 measurement is an error). Of course the amounts and geometry also matter.

Click to access en20110327-1-5.pdf

Report of ionide-134 [sic] error:

Click to access en20110328-1-1.pdf

* I’ve made comments, on my blog, about the measurements of I-131 and Cs-137 fallout in (unevacuated) parts of Fukushima prefecture, e.g. Iitate. Cs-137 deposition has been inferred in the range of 3 – 8 MBq/m^2. How should this be interpreted?


Being very familiar with the designs of modern plant that would be built today (contrasting the out of date Fukushima plant), I would like to add my analysis of why I believe an accident of this magnitude could not occur in a modern reactor such as the EPR or AP1000:

Most importantly, the back-up power systems could not be simply washed away by a tsunami as they were at Fukushima –

In the EPR design, there are four separate ‘redundant’ diesel generating systems, two of which are bunkered and waterproofed, each capable of keeping the core within safe temperatures following shutdown. If built near the coast, the diesels could be placed on the side of the containment furthest away from the sea, and so use it as a further barrier to extreme weather, such as tsunami.

In the AP1000, all the safety back-ups are protected within the containment and exterior shield building, and so would not be at risk from even the most extreme weather anomalies. The safety systems do not require fuel, as they are designed to allow water to simply fall into the core under gravity and circulate via natural convection etc.

Even if all these safety systems failed and there was fuel melt, the external radiological consequences would still not be as high as even the relatively minor release experienced at Fukushima. Firstly, both plants have hydrogen mitigation systems, so no scary explosions. Further, the EPR has a double layer containment and corium spreading pit (nothing is getting out of there) and the AP1000’s steel containment can be cooled from outside almost indefinitely.

Long story short, the main technical lesson to be learned from Fukushima is: Build new reactors!

MODERATOR: Typo in first sentence fixed


On topic — what these threads really need is a YCombinator-style tree hierarchy for comments. It would be much easier to follow discussions of the size this blog gets.
See Barry’s remarks at 11:16 am


For the Fukushima reactors, does anyone happen to know, or perhaps have resources where you could find out:

1) just where the dry well containment atmospheric monitoring system radiation monitors are located?
***I’m wondering if they are external to the dry well (e.g., still reading air) or
***if they are actually in the dry well, in which case, they’d be under water now since they’ve been flooding containment, right?

2) just what type of monitors they’re actually using?

3) what is the normal range for those rad monitors
***under operating conditions, and
***post shut down (1 to 30 days, but I’ll take any data!)

Thanks in advance!!


well, this sounds pretty wild (see below). Note that even tho the wording would lead one to assume that options in the second paragraph are being considered by the experts, what it REALLY says is that the media has said those things. So, maybe the experts have discussed those, maybe they haven’t, who knows.

…Chief Cabinet Secretary Yukio Edano told a news conference that the government and nuclear experts are discussing ”every possibility” to bring the plant under control and that some measures that have been reported by the media are included in their options.

Media reports said that the government and the experts have been studying the feasibility of new steps such as covering reactors of the plant with special cloth to reduce the amount of radioactive particles flying away from the facility and using a big tanker to collect the contaminated water….


What are the levels of radioactivity in the control rooms? Why do *three* reactors have very, very radioactive water in the turbine rooms?



I think you mis-posted this comment:
“Please keep all dialogue here to general and philosophical discussions on nuclear power, its benefits and limitations, its alternatives, history, media treatment of the FD accident, your views on how the world should work and why people should listen to you, etc., etc. Nothing technical please — leave that for the other FD open thread. […]”

Rational Debate,
Dry monitors are usually super sensitive, capable of reading well below background and installed in specially shielded boxes (we use boxes made of lead that was smelted more than 2,000 years ago).

Thus we can measure tiny amounts of radioactivity in air but usually it is unimportant owing to the very short lifetime of the radioactive isotopes of Oxygen and Nitrogen.

Wet wells are something else as we are looking at ground water that will likely contain sodium and chlorine. Personally I don’t take much notice of Chlorine but sodium can present some problems with its many active isotopes.


Live NHK TV reports that some people are filtering back into the 20km area to check on livestock, and property. Of course, they’re not supposed to. It’ll complicate any dose estimates if much of this happens, but I suppose the only surprising aspect is clearly some aren’t that scared of the radiation.


Apparently they are thinking that some/much of the trench water is from the tsunami (seems likely to me). The entire area has got to be pretty saturated from the tsunami. I am sorry that I don’t recall for sure where I heard or read this – I think NHK live TV but I’m not certain.



Why do *three* reactors have very, very radioactive water in the turbine rooms?

Boiling water reactors have steam from the primary cooling loop water directly driving the turbine. The turbine hall is connected via the steam pipes to the reactor core.


NHK live TV reporting that at Ofunato (sp??), near Sundaii (sp??) is so far the highest spot where the tsunami came in. Apparently there the tsunami reached the top of a cliff (hill?) that was 29.6 meters high. Which I just HAVE to put into feet, for those of us who don’t think in meters – the blasted thing was over 97 feet high!!!! I’m sure it had to have been like the video that Barry posted on another thread – not some giant breaking/crashing wave coming on like a 97 foot high wall, but just the water rising and rising and rising…. ah, here’s a link & story (below). There is a video at the site too.

They’re also reporting supercritical flow at another site – I didn’t catch exactly what the mechanism is, but apparently the result is water moving overland at extreme velocities. One woman was quoted as saying the water was moving almost as fast as the bullet train. Here’s an article that talks about one mechanism (maybe the ony one? I don’t know), scroll down to the colored mockup, and read the paragraph below. It notes speeds up to 40+ mph (19 m/s) in one known case. I couldn’t find a link on NHK with the details that they were reporting on the live TV.

Researchers: 30-meter tsunami in Ofunato

The latest research on the March 11 tsunami that slammed into Ofunato city in Iwate Prefecture, northern Japan shows that it was nearly 30 meters high.

A joint research team from Yokohama National University and University of Tokyo surveying the Ofunato city shoreline made the discovery.

They found fishing equipment scattered on the high cliff of the city’s Ryori Bay and have determined the tsunami reached as high as 29.6 meters.

The research group says the great height of the tsunami was formed by the shape of the narrow bay. They will continue to survey traces of the tsunami to clarify the scale the tsunami.

Wednesday, March 30, 2011 06:25 +0900 (JST)


re post by: Jan, on 30 March 2011 at 2:20 PM said:

I’ve a question. There is measured by TEPCO the quite suspicious 2.6E-02Bq/cm3 of Te-129 see: Where this comes from?

Hi Jan,

We’ve discussed this on other threads. I haven’t read your link, but I wouldn’t think Te-129 would be a big surprise. Hopefully this will work, I’ve never tired copying a comment link from the date…. but try this and see if it doesn’t get you to one of our earlier discussions where you can see what has been said about Te-129 previously and then we can talk about it more here if you have more questions/commments:


re post by: gallopingcamel, on 30 March 2011 at 3:07 PM

Gallopin’ are you referring to the Fukushima dry well CAMS? I was pretty sure that those were high level monitors (very high actually), not low…


Ok, it’s going to be wild if they tent the reactor’s to ‘catch’ radioactive particles! Apparently that really is under consideration. I’m not sure what they’d do that way – but suspect it would be a first. Wonder what sort of ‘cloth’ they’re considering…


re post by: Finrod, on 30 March 2011 at 3:34 PM said:

@bks: Why do *three* reactors have very, very radioactive water in the turbine rooms?

Boiling water reactors have steam from the primary cooling loop water directly driving the turbine. The turbine hall is connected via the steam pipes to the reactor core.

I would think that radwaste sumps and associated piping and systems and other water control systems on site have to be considered also. Particularly considering the tsunami flooding the entire area.


A bit of breaking news on the BBC,

‘Japan to scrap stricken nuclear reactors

Japan is to decommission four stricken reactors at the quake-hit Fukushima nuclear plant, the operator says.’

What do they mean?! I did not think they would be using them again. What are the implications. How does it change the way they do things? (What is this message meant to mean. Is it code for something?)


One of my friends in a different forum (who has been a bit on the hysterical side throughout all this) reposted a news item reporting a fellow named Richard Lahey (a General Electric identity,allegedly head of reactor safety) suggesting that in his opinion, the readings suggested that the reactor core had melted through containment.

This seemed at best fishy to me (especially since it hadn’t been mentioned in other news sources), so I wanted to get some idea where this had come from. Does anyone know?

Thanks in advance,



Cross posting from open thread 2:

re post by: EL, on 30 March 2011 at 9:32 AM said:

@ David Kahana or others, re Cl-38 in samples

You can find a full discussion (and lots of math) regarding transient criticality and Cl-38 in the sample water of reactor #1 here:

Click to access Cause_of_the_high_Cl38_Radioactivity.pdf

Comes from Arms Control Wonk blog. And you’ll notice Red_Blue has already had his/her say in the comments.

El, the author launches into all sorts of calculations without first looking at the big picture. If there were Cl activation, there would also be significant Na activation. No activated sodium was found apparently. Other short lived fission products that would be expected to be found in significant quantities weren’t either. That puts a rather large hole into the scenarios proposed in that paper, or in the idea of Cl-38 arising from a re-criticality.

I’ll cross post this over on the technical open thread where it would make more sense for us to continue discussions on this issue if desired.


TEPCO’s March 29 assertions mentioned by Barry at 11.45 am should be considered together with this reuters report claiming that they in 2007 they had an internal study estimating a 10% probability of a bigger Tsunami than design basis within 50 years but did nothing about it.


“We’ve discussed this on other threads. I haven’t read your link, but I wouldn’t think Te-129 would be a big surprise. ”

Hi RD,

To me in this

Click to access 110328i.pdf

Click to access 110328h.pdf

the Te-129/Te-129m ratio difference is quite troubling
They I think shouldn’t differ in distribution so much.
Of course it could be another error in measurements. But it looks like a day before
5.2E-02Bq/cm-3 Te-129 was detected too: at E-2 value
It would suggest the Te-129 either war there in unusual quantities, or it came into being relatively recently. which would suggest this measurement from 3/22: wih value at E-3
and this from 3/24: with value at E0
The beta chain here :

I think the Te-129 values are pretty weird
What could it mean??


@Huw Jones, on 30 March 2011 at 12:28 PM said:
“… an accident of this magnitude could not occur in a modern reactor such as the EPR or AP1000”

Apart from the over-confident “could not occur” I accept that the AP1000 is much safer, but several questions and issues remain:
.1 the fact that the US began many of these design alterations as early as 1972 shows that the stronger regulation in the US and Europe is totally justified. I raise this because both BB and many pro-nuclear advocates have complained that regulation in the west is too zealous and unnecessarily increases the cost and time of construction.
.2 Given that the Fukushima type reactor and its descendants are the most common type, how many of the >400 extant reactors meet the higher standards discussed by HJ? Especially outside the US. Generally speaking I would be in admiration of Chinese engineering projects, however the huge cost of these things and the huge demand on concrete and steel makes one nervous, not so much about the government, but about the contractors building them to cut corners. Even in Japan there were dark stories about contractors bulking up with straw, some of the concrete structures that collapsed in the Kobe earthquake.
.3 re: “could not occur”. The weakness in the Japanese design was that all the backup systems failed because they all relied upon the same electrical control room, switching room and pump room (which to this day, despite restitution of mains power remain unrepaired). Except for their Pacific coast, tsunamis are not the rogue issue for the US but apparently many experts claim that there is an equivalent risk in fire, which is a common occurrence from earthquakes (many examples must have been documented on the BNC site; it was true with the 2007 Chūetsu offshore earthquake that shutdown all the Kashiwazaki-Kariwa reactors.)
I pointed out this flaw in my Crikey summary of 16 March, and so unlike most commentators was not surprised that the mere reconnection of mains power has still not restored normal cooling, absolutely critical to stop things getting worse.
Below is a fuller explanation of this weakness. (This is my selection/extract from the much longer article.)
Disasters Fail to Follow Scripts Updated March 13, 2011, 09:31 PM
David Lochbaum, a nuclear engineer, is director of the Nuclear Safety Project of the Union of Concerned Scientists. He has worked at three reactors in the United States with designs similar to the Daiichi nuclear plant in Japan and has worked as a technology instructor for the federal Nuclear Regulatory Commission.

The primary challenge for the Japanese reactors apparently resulted from losing both their normal and back-up power supplies. The reactors were designed to cope with this situation for only eight hours, assuming that normal or back-up power would be restored within that time.
Most U.S. reactors are designed to cope with power outages lasting only four hours.
We know that earthquakes can cause fires at nuclear reactors, and U.S. reactor safety studies conclude that fire can be a dominant risk for reactor core damage by disabling primary and back-up emergency systems. Yet dozens of nuclear reactors in the U.S. have operated for years in violation of federal fire protection regulations with no plans to address these safety risks anytime soon.
Finally, there is the issue of protecting nearby communities. The breadth of the disaster in Japan overwhelmed emergency response capabilities. Reactor emergency plans in the U.S. rely on the assumption that a reactor accident would be the only demand on emergency response resources.


In my opinion the Te-129 issue is quite very surprising.
The Te-129 measurements in the air are quite erratic and if they’re not another measurement errors they would strongly suggest massive concentration change UP very recently between 3/23 and 3/24 because the Te-129 value jumps from order E-3 to E-0, also the Te-129/Te129m ratio changes massively throughout the later measurements which could be due to different half-lifes, but the ratios don’t match and Te-129, which has much shorter half-life than Te-129m looks like it sharply rises its ratio to Te-129m
What could it mean?

to admins:
to limit the amount of links in a post is pretty nonsense, this is a technical debate, so to provide links to multiple sources is important. like this you must unfortunately find it for yourself from Tepco measurements.
I am not quite sure as to what you are alluding. Refs/Links are actually encouraged by BNC. Too many links in a comment, however, do sometimes mean that the comment may be deemed spam by WordPress. I will pass this on to Barry for comment.


Johno —

One of my friends in a different forum (who has been a bit on the hysterical side throughout all this) reposted a news item reporting a fellow named Richard Lahey (a General Electric identity,allegedly head of reactor safety) suggesting that in his opinion, the readings suggested that the reactor core had melted through containment.

This seemed at best fishy to me (especially since it hadn’t been mentioned in other news sources), so I wanted to get some idea where this had come from. Does anyone know?

This is reported in the Guardian, a perfectly credible British newspaper:

Richard Lahey, who was head of safety research for boiling-water reactors at General Electric when the company installed the units at Fukushima, told the Guardian workers at the site appeared to have “lost the race” to save the reactor, but said there was no danger of a Chernobyl-style catastrophe.


At least part of the molten core, which includes melted fuel rods and zirconium alloy cladding, seemed to have sunk through the steel “lower head” of the pressure vessel around reactor two, Lahey said.

“The indications we have, from the reactor to radiation readings and the materials they are seeing, suggest that the core has melted through the bottom of the pressure vessel in unit two, and at least some of it is down on the floor of the drywell,” Lahey said. “I hope I am wrong, but that is certainly what the evidence is pointing towards.”

Professor Lahey’s university biography:


Just heard on NHK that the other Fukushima plant Dai-ni has been observed having smoke coming out of one of the turbine buildings. It has stopped, but I want to know if this is also in trouble. Why do they observe the smoke but not know why. Feels a bit like they are not in control.

Anyone know the situation?


Rational Debate,
To clarify my earlier comment I was talking about what we do in North Carolina so things may be slightly different in Fukushima.

Most of our area monitors have local displays which can be read from at least 50 feet away. While the instruments can read down to background, anything below 1 milli=Rem /hour displays as “Zero”. Depending on location these monitors are set to alarm at a few milli-Rems/hour.

The really sensitive instruments are used in the air quality monitors in the very high radiation areas where there can be measurable activation of the air. These monitors are inside specially shielded boxes made of ancient lead to ensure that they are not affected by anything but the air circulated through the box.


Several comments have suggested that keeping one of the power plants in service (or hastily returning it to service) could have solved the power problems which were due to the tsunami taking out all 13 diesel power plants at Fukushima Daiichi.

Not so.

See my post on the philosophical thread, several minutes ago for a more detailed discussion.


I think others have mentioned the document containing Pu soil measurements –

It seems to me that the concentrations of Pu in the soil around the site are unremarkably low – note that the MEXT standard levels for “ordinary domestic soil” are:

Pu-238: 0 – 0.15 Bq/kg
Pu-239/240: 0 – 4.5 Bq/kg

The highest amounts detected of each nuclide were (5.4 +- 0.62) x 10^-1 Bq/kg for Pu-238 and 1.2 +- 0.12 Bq/kg for Pu-239 and Pu-240.

Is it just me, or are those levels unsurprising/underwhelming? We’re talking almost 2 seconds/kg between Pu-238 decays.


@John Bennetts, on 30 March 2011 at 10:45 PM

The problem was and is, to this day, that the various control rooms were flooded and could/still cannot be reconnected to power. One week after mains power restoration they still haven’t been reconnected (except for lighting!). Mains power would have been more convenient because they did have trouble with provisioning diesel–actually running out at different times. Indeed this loss of normal cooling circuits has been THE central issue which has forced them to use firetrucks to pump in seawater.

JB, you have no excuse for not knowing if you read your Crikey, because I pointed it out two weeks ago on the 16th:



Fair enough. We tend to agree regarding power, although coming at the issue from different directions.

Regarding Crikey, I have tended to spend more time on BNC lately and less on the Crikey that I pay real after-tax money for. Living in NSW as I do, the political stuff has been a bit over the top lately and the rest, well, is less relevant to the real world than that which is happening in Japan and its possible effects on our futures.


Just re-read MRJ’s article he mentioned above. No mention of what I wrote about, the theory of keeping one NPP awake to provide power for 5 others.

It still isn’t possible.


@John Bennetts, on 30 March 2011 at 10:45 PM

Incidentally this issue (slow re-installation of control rooms etc) and today’s report of steam from one reactor at Dai-ni, raises again to me a mystery. Why did Dai-ni escape apparently scot free? Apparently the tsunami was just as high there. So did the design of the plant provide more protection (bunkered & waterproofed)? I have never seen anything written anywhere that comments on this huge difference. Dai-ni reactors were built a decade later so one could infer (as much as I hate getting into a speculative loop like so many comments on this site) that the Japanese/TEPCO knows perfectly well how to build properly protected plant and just kept running the old ones hoping for the best. (Just in February they won a 10 year extended life for Dai-ichi #1, the oldest one.)
Note also that Dai-ichi #5 #6 have had no problems (apparently, despite outside experts worrying about them) but are only a few years younger than the others at Dai-ichi, but you can see these two are physically separate to the others. They had fuel in the SFP storage (and #6 had the most because it is the only 1.1GW reactor on the site).


JB, I didn’t claim I wrote about what you did today. I said that what you wrote about was beside the point (well, I wasn’t so blunt in my first post but that was it).
Just in case it is still unclear: even if one of the NPPs could have kept running, it would have made no difference (other than a bit more convenient–avoiding diesel issues).


Sorry not to provide a link. I read somewhere today that the newer power station is actually quite a bit higher than the older one.

I guess that, being a decade newer, might also have made a difference in terms of watertightness of switchboards, building layout (shielding from the tsunami) or many other small hypothetical ways.

Without a site plan and witness reports, however, this will remain just conjecture.

Time will tell. Surely, there has been enough bad luck already?

BTW, I notice that you, like me, have confused the names of the two power stations. Fukushima A and Fukushima B sound good enough for me, akin to Loy Yang A and Loy Yang B or the former alphabet stations at Vales Point and Wallerawang in NSW.


Hello everyone. I am interested in the rough cost of possible upgrades to existing older plants, such as
– very tall tsunami walls
– full passive steam powered pumps and valves
– much more battery capacity (say 10x more?)
– very large eathquake and tsunami proof demineralized water supply tanks next to the plants
– etc,

What would be the cheapest combination of upgrades to get some serious tsunami protection for Japan coastal plants?


Question on mechanical aspects.

Putting waste water from the flooded turbine room into the condenser seems like a bad place to put it as it communicates w/ the sea water used to cool the condenser. I heard earlier it was not the condenser but the condenser TANK. Can anyone add some details??



here there is a very interesting interactive map of all the Geiger meters of Japan, each one has the location, the average reading* and the organization managing it.
very useful for a general look of the network, for historical reference. hoping to be useful

* of course, the average reading of the meters surrounding Fukushima are a bit biased due to the last events….


@John Bennetts, on 30 March 2011 at 11:58 PM

“this will remain just conjecture.”
Quite but why would it not be worthy of mention? (It is the nitpicky scientist in me. I want to know.)

“BTW, I notice that you, like me, have confused the names of the two power stations. Fukushima A and Fukushima B sound good enough for me, akin to Loy Yang A and Loy Yang B or the former alphabet stations at Vales Point and Wallerawang in NSW.”

Hmm. Trying to figure what you mean. It’s near midnight so could easily makes error but I checked what I wrote and I don’t think I got anything mixed up. Fukushima-I = “Dai-ichi” with 4 of 6 reactors in trouble, while Fukushima-II = “Dai-ni” with 4 reactors in cold shutdown.
@Cyril R.
Read Huw Jones, on 30 March 2011 at 12:28 PM about the American regulators changes to the design of these things (in the AP1000). You’ve really got to protect the control room and all important mechanicals (pumps etc). Probably making battery installation that big might be more trouble than it is worth; I am wondering how the batteries survived the tsunami when everything else didn’t.


MRJ: Correct, it is late. My bad. I still favour A and B.

Re battery rooms, it is common practice in coal fired stations to locate the battery rooms very close to the control rooms, to ensure max possible security of DC backup for control systems. Plant control rooms tend to be a bit elevated because the operating floors are at turbine level. The same kind of reasoning might have placed the batteries above the worst of the tsunami. Again, only conjecture until actual layout drawings come to light, but certainly plausible.


For new designs yes this is easy with passive features but what about existing ones, especially older ones on the Japan coast?

Batteries can be made very robust and water resistant. If they are just for some valve actuation and some critical DC controls, they are not very high power systems, and maybe several days of deep cycle lead acid won’t be all that expensive? Couple million more in batteries isn’t going to break the bank. Or there could be a separate diesel generator to charge the batteries up so that they can last a couple weeks?

It seems to me that some quite cheap upgrades can be done to the older plants to make the Fukushima proof. Closing them down means more fossil fuels that kill people all the time, pollute the air a lot and could cause possible severe climate events.


@michael r. james, on 30 March 2011 at 11:46 PM said:

Note also that Dai-ichi #5 #6 have had no problems

Dai-ichi #4, #5 and #6 we out of service at the time of the quake.

Daichi #4 had a full core offload in the spent fuel pool.

Click to access ENGNEWS01_1301489625P.pdf

It’s a common industry practice(at least according to NRC documents I have read) to offload all the fuel during refueling, then replace about 1/3rd of it then load that back into the core.

So it was a ‘worst possible time’ at reactor #4 to lose power to the spent fuel pool. It had a full hot core sitting in it. Number of fuel assemblies in a pool is part of the story. How long they’ve been there is just as important.


I posted the question on the 3/26 thread with no response but that is probably because everyone moved over here “overnight” (for me ;-)

so the French appear to want to come help “dispose” of the radioactive water.

dumb question: does this mean burying it in a tank somewhere for x number of years, or did I read correctly that there is technology that exists that can “clean” (filter? forgive my layman’s terms) the water so it is not so “dangerous?

NHK’s statements implied a way to rectify the situation with the contaminated water instead of simple disposal….


@GSB 12:05 AM The following is my opinion based on large steam turbines in the process industry, not nuclear power plants. The basic principles are the same.

Turbine steam condensers are horizontal heat exchangers with the steam on the shell side, condensing on many rows of horizontal tubes which have pumped cold seawater flowing inside them.

The condenser heat exchangers drain the condensed steam into (horizontal) large pressure vessels. These vessels may operate 50-60% full and act as surge volume in the system. They operate at ~atmospheric pressure, +/- alittle bit. The surge vessels may be separate from the condenser or be built in one large common shell with the condenser tubes above the water surge volume.

Below the condensed steam surge vessel are the primary circulation pumps. The are located below the vessel so they have a head of water for the pumps to work properly (net positive suction head).

There are probably secondary circulation pumps to boost the reirculated water up to ~1000 psig which is the operating RPV pressure.

Depending on the condenser surge vessels size and the amount of water in them post shutdown, there may be room for some additional contaminated water in them, if a way of pumping into them could be found.


Thx for the response Leo that makes sense– the condensate tanks more than likely would be isolated from the sea water side of the heat exchanger.

I conjecture that there might me one or more breaks in the primary steam turbine loop from the earthquake….on this BWR design there is only one loop so radioactive water left in the loop could leak out in any number of places and it is my guess that perhaps this is where the water in the turbine room has come from (pure specualtion).

If there are breaks in the primary turbine loop how does this inhibit getting the cooling pumps going again??? Is the cooling loop they are trying to get started part of the primary loop or is it a second, smaller and simpler loop that could be used independently from the primary loop.



Folks: I posted on the philosophical thread a scary story about the effects of a meltdown along with a much less scary story from the guardian. The titles appear to be antithetical. I should have posted here.

Can someone who knows what enough chemistry comment?


I have a friend in the GE power division and he says TEPCO just placed an order for 40 new 9F gas turbines to replace the load. (10 GW total output). To be fueled on DF2. Not known is if they will be combined cycle units.


re post by: Jan, on 30 March 2011 at 6:20 PM

Hi Jan,

I’m not ignoring your question, just have to get time to take a closer look at the data & ratios. If you feel like pulling the actual number out and posting them that would help. I’ll try to take a look later today.


re post by: MuadDave, on 30 March 2011 at 11:20 PM:

Is it just me, or are those levels unsurprising/underwhelming? …Pu-238 decays.

Nope, Maud, it’s not just you. That’s a huge problem for the industry wrt both regulatory limits and even more, public opinion/understanding, especially in crises like this, as rare as they occur. We can measure radioactivity down to such utterly minute levels, yet we are tied to ALARA (As Low As Reasonably Achievable) in terms of both occupational and public doses – and yet anytime any radiation is measured, many in the public get worried because ‘that must be bad, right?’

Anyhow, in answering your question I’m forced to bring up issues that are probably better suited to the philosophical thread, but I was trying to answer your question – e.g., ya, those plutonium measurements so far are extremely low, you are exactly right.


@Hank Roberts,

large amounts of this water is salt water – is there much history in the area of decontaminating sea water using that technique?

Would the intention be to distill the water first?



thanks Hank: DV is trying to find out more about this guy. See the phil thread.

anyone have any comments on the NEI retraction about the possibility of Zirconium Fires. Rod Adams featured this NEI factsheet, now altered, and it has caused some embarrassment.

anyone know the status of the discussion on zirconium fires in drained spfs?


@ George Bower – they pumped into the condenser tanks. The problem is there wasn’t much space available in the tanks.


George Bower, on 31 March 2011 at 3:03 AM

George, I’m not a system’s engineer, but I can’t imagine that they’d be trying to start up anything associated with the primary turbine loop. There are a few different cooling loops that they may be trying to restart – residual heat removal (RHR) the most likely one I’d think – but it would all depend on just what pumps or electrical circuits, etc., are damaged, and how easily or fast they can repair or work around what ever problems they find.

For a quick overview of the different systems they might be trying, see:


re post by: gallopingcamel, on 30 March 2011 at 10:25 PM

Thanks Gallopingcamel. Here’s what I’m trying to get at. The Fukushima data is showing massively high dose rates in their dry well CAMS. I’m trying to figure out just what the significance of that is in terms of plant/core/RPV condition – but I’m not certain of a couple of key aspects:

Where those would actually be placed – I mean, they’ve been flooding the drywell, right? So if the CAMS are inside the drywell, they’d be underwater. ***If that’s the case, any idea what that would do to readings?

Huh, just occurred to me – I wonder if the placement is such that it might have gotten hot enough to melt the lead (327.5 C)? If we lost the lead shielding, any idea what sort of dose rate they be likely to see from shine, assuming no core damage?

Shoot, GallopingCamel, any thoughts one way or the other about the screamin’ CAM readings? It’s at all three units, although there is some variation. I can find you a link if you haven’t seen the data, its one of the pdf type reports, so I think it’s either nisa or jaic, maybe the latter…


re post by: Gregory Meyerson, on 31 March 2011 at 5:32 AM

Gregory a link to the retraction or NEI story you’re referring to would help.

I haven’t seen much of anyone discussing zirc fires in the SFP’s for days now. It seems to have dropped off the map in terms of concern shortly after they began spraying the pools.


Plutonium Toxicity

Rod Adams posted “How Deadly is Plutonium?” in 1995 His article quotes Berhard Cohen. (Cohen’s piece on Pu is here

Cohen once issued a public challenge to Ralph Nader – Cohen volunteered to eat as much plutonium by weight as Nader would eat pure caffeine . Nader chickened out. Cohen was serious.

Rod also writes about the 26 men who ingested Plutonium far in excess of the supposedly lethal dose during the Manhattan Project who were studied for many decades afterward.

Rod doesn’t appear to mention the IPPu club. Maybe you’ll have to ask him.


I posted a question on the emergency core cooling system and whether or not it is a separate loop to the main turbine loop.

I did some googling and found a very good technical discussion of the various cooling loops. They are separate loops.

The nrc description is here:

Click to access 03.pdf


Plutonium stays in the body when ingested or stuck in the lung. It then goes and radiolyses your body cells and water from within, nasty.

However, different isotopes of plutonium have huge differences in biotoxicity. Pu-238 is very dangerous when ingested, possibly over half of it will decay in your body, Pu-244 really not so much because it is very long lived, very slooooow decaying, a fraction of a fraction of a fraction will decay in your body. If the contest would be to eat pure caffeine or Pu-244 I’d take the Pu-244, but contests like that are silly sensationalism if you ask me, though Cohen’s point was made quite clear…

Most Pu from the reactor will be Pu239 and Pu240, both also orders of magnitude less dangerous than Pu238.


Some posters in previous threads on this site seemed to discount the report that reactor unit 2 appears to have melted down through the bottom of the containment vessel (source: Those posters stated that the steel of the primary containment vessel was too thick to melt through, even with fuel rods being partially exposed for weeks and temperatures in the reactors exceeding design criteria. However, there are other factors that may have caused the reactors to lose containment.

I’m wondering whether the fact that these reactors are nearly 40 years old has anything to do with the escape of radiation from the containment vessels presumed to have occurred in reactor unit 2 and the cracks that have been reported in reactor units 1 and 3. Embrittlement is a known problem in older reactors (sources: and

Is it possible that the spraying of cold water on the hot pressure vesselsl could have opened cracks in these old reactors, weakened from decades of embrittlement? Could embrittlement have weakend the pressure vessels enough to have caused them to lose containment due to the stress caused by these changing temperatures?

Also, “in 2002, an undetected boric acid leak at the Davis-Besse nuclear power plant in Ohio ate through most of the 6-inch-thick steel reactor head. When the leak was discovered, only 3/8 inch remained.” (source: Is it possible that chemical reactions with the boron or impurities in the seawater could cause something similiar to occur in these reactor vessels?


i am looking for radiation measurements on land from 1-10 km from the power plant. Anybody know any good sites (I find lots inside the gates and >20 km, and a few marine measurements, but none on the ground). Thanks.


Apologies if this has already been posted elsewhere, but the U.S. Dept of Energy has put up results of airborne radiometric surveys in the vicinity of Fukushima. The data show the main plume on land extending north-west from the plant. It’s instructive to compare the latest survey (from flights on March 24 & 26) with the earlier flying (prior to March 22). The radiation appears to have diminished considerably, which says to me that the bulk of it comprises the short half-life I-131.

Nature out today does the service of converting the earlier map (but note, not the latter updated one) into SI units, for non-American readers, within what is generally a reasonable piece.


I am not quite sure as to what you are alluding. Refs/Links are actually encouraged by BNC. Too many links in a comment, however, do sometimes mean that the comment may be deemed spam by WordPress. I will pass this on to Barry for comment.”

Yeah, I was posting the first post with links, when it told me something like that. So then I wrote the post without links.

Back to the topic, here I’ve put together the available Te129/Te129m data:

The large jumps 1-3 orders of magnitude UP can be measurement errors, of course, or a secretary wrote something wrong, or whatever. Problem is there shouldn’t be any Te-129 at least not with Bq ratio 13500 to Te-129m in first place, because Te-129 has 69.6 min half-life and his parent Sb-129 4,4 hours and its beta parents some seconds.
see here:


I’m not sure exactly what the data are that you are looking at, but consider this: Te-129m is a direct fission product, and also, I think, that some of the decays of Sb-129 go to Te-129m as well as Te-129. Te-129m has a half-life of 33.6 days and decays to Te-129. So the activity of Te-129 should be the same as the activity of Te-129m at this time.


I don’t get it.

I read an article on the ABC website this morning stating that there’s massive releases of radiation, along with recriticality, and meltdown in #2 reactor.

Then I look at the updates on here, to find the temperatures at the bottom of the #2 reactor pressure vessels is 88 degrees C, which hardly indicates meltdown.

Where is the ABC getting it’s “information” from?

It seems more likely that the only meltdown is in the media, yet again.


The latest bulletin from TEPCO supports the thesis that the tsunami may have contributed much of the water in the flooded trenches. The volume of these trenches appears to be some 3100 cubic metres.

No explanation is available yet for the pathway accounting for the unit 2 trench surface measurement in excess of 1000 millisieverts per hour (same as unit 2 turbine building water).

I think the simplest explanation continues to be valves and seals as proposed here, and updated last night 3/30 here.


Is this the correct thread for posting Fukushima Daiichi?
Right thread for up-dates on the situation at Fukushima. Switch to technical OT if you wish to elaborate at length on the current readings, reactor situation etc.


From the 2001 Sep 11 World Trade Center experience, only aiplane wheels retained enough kenetic energy to pass through the sturctures in recognizable condition. A pothograph sequence of a jet fighter flown into a concrete wall in a test at Sandia resulted in a totally destroyed aircraft and a small chunk of missing wall, maybe 20 cm in diameter and 5 cm deep at the center.

Of course the newer designs which place the reactor underground are superior in that it is essentially impossible to fly an airplane to impact the reactor vessel; see the just previously given link to a small modular reactor survey.


Well, an IEEE Tech Talk note doesn’t make the Lahey perspective correct. But it is clear that he stands behind his interpretation (quoted in The Guardian). Exerpt:

This morning, Lahey elaborated on his analysis for IEEE Spectrum, which he said had been accurately reported by The Guardian, but misinterpreted by some. (A careless read of the article suggests a new melt down at the plant, rather an analysis of what probably occurred early on in the crisis.)

Lahey says his analysis was based on the data sources seen by him and colleagues around the world, but that the information has been inconsistent and changes hourly. “It’s really hard to read the tea leaves,” Lahey says. “They keep blowing around… I may be wrong. I hope I’m wrong.”

However, his best take is that “all cores have melted, and it appears as though Unit 2 has melted through.”

Still missing is Lahey’s specific observations indicate in particular that “Unit 2 has melted through.” The concluding paragraph:

Our correspondent, John Boyd, questioned experts in Japan about Lahey’s claim, but they were doubtful. Hidehiko Nishiyama, the deputy director general of theNuclear Industry and Safety Agency (NISA), did not see evidence of a big breach of the pressure vessel, but acknowledged that its not completely contained. “When we look at the release of radioactive material up to now, while we do not believe there is any major breach either to the pressure vessel or the containment vessel, we are pretty sure there is some leakage,” he told Boyd.


“Te-129m has a half-life of 33.6 days and decays to Te-129. So the activity of Te-129 should be the same as the activity of Te-129m at this time.”

Yeah, exactly, in a certain ratio.
Yet somehow there are the large even multiple orders of magnitude fluctuations of the Te-129.
Are this another errors in the TEPCO measurements, or does it signify something?
I don’t know, that’s why I’m asking.

Another thing – here I’m writing a paper about the Austrian Met-office crazy figures about the Fukushima fallout comparing Cs-137 discharges to “20-60%” of that at Chernobyl:

Click to access Does%20Fukushima%20radioactive%20fallout%20near%20Chernobyl%20levels.pdf

I would be glad if somebody looks at it – I’m not at all a nuclear energy expert.


Mentions what’s been a concern all the way along, that fuel may have fallen into configurations that have allowed bursts of criticality. This kind of accident has happened often enough to be fairly well known — it’s a very fast and usually very brief event because it heats up the material and that usually separates the fissionables or boils water that’s moderating neutrons (slowing them down, which makes more fission events happen).

New readers should look at the word “moderation” — slowing down neutrons, “moderating” them, makes fission events increase, not decrease. Water is a moderator; water vapor isn’t, so when a fissionable material that includes water reaches criticality it boils — and its density decreases, the water goes away, the neutrons are no longer moderated, and the criticality stops.

Some criticality accidents have cycled that way — flash to criticality, heat, boil, cool, condense, flash — until enough water boiled away or boron was added or other interventions interrupted the problem.

Japan has had experience with this in the recent past.

The chlorine isotope discussed in the Bloomberg news story linked above is the evidence for this happening now, somewhere in one of the plants.



Hi Jan,

Ok, I’ve taken a look at the readings you pulled together (thank you!), and honestly don’t see anything that looks like a concern to me. I’d have to do some actual calculations to be sure, but there are a number of factors to consider that are affecting these numbers.

First, recall that Te-129m has ~34 day half life – and it’s primary mode of decay is to drop back to Te-129. (branching factor is about 63%). So as long as we’ve got Te-129, we’ll have Te-129 also. I think this may be the biggest piece that you’re missing.

Next, these are atmospheric readings taken in the open. Not only will we get variation based on wind conditions, precipitation, etc., but also there is almost certainly some variation in how much is being released from the plants.

So the amounts will vary from day to day just because of those factors.

It’s made even more difficult because the data is spotty – we don’t even have every day at each location for both isotopes…

So the portal sample Te-129 increase from the 23rd to the 24th, for example, could easily be because a lot of Te-129m was present shortly before that (e.g., from the 23rd, where we don’t have a reading), or because more radioisotopes of all types happened to be released, or blown, to that location on the 24th than on the 23rd… or a combination of all of these factors.

I had also replied shortly after your first post on this, with a link to where we had discussed this before, did you read that link? It was from my post here: Rational Debate, on 30 March 2011 at 4:51 PM said:
where I’d given a link to:

Does this help?


I sure have no idea regarding the many various reports of activity. I can make no sense of them myself. There are so many inconsistancies in the reported isotopes that I have about given up trying to understand them. I was just trying to address your comment about the fact that there should not be any Te-129 present at this time, due to its short half-life.


David Lewis, on 31 March 2011 at 6:12 AM said:

Of course Nader should have said he would breathe as much caffeine aerosol as Cohen would breathe in Plutonium aerosol.

Then no doubt, Cohen would have chickened out, or natural selection will have taken its natural course.


Nuclear toxicity

The relatively recent increase in background radiation due to medical, military, and civilian nuclear industry seems somewhat accompanied by increasing cancer rates as other causes are removed (cigarettes, lifestyle).

A WHO report says:

“… cancer rates are set to increase at an alarming rate globally. We can make a difference by taking action today. We have the opportunity to stem this increase. This report calls on Governments, health practitioners and the general public to take urgent action. Action now can prevent one third of cancers, cure another third, and provide good, palliative care to the remaining third who need it, “said Dr. Paul Kleihues, Director of the International Agency for Research on Cancer (IARC) and co-editor of the World Cancer Report.

see, for example:
You are skating on thin ice here Chris. I could delete this post on the basis that you are deliberately distorting the facts and providing links which do not support what you are saying. I am leaving it up un-edited as an example of what occurs. Further violations of the BNC Commenting Rules will result in editing/deleting of your comment.
Everyone, please check the BNC Commenting Rules before submitting your comment or risk having it edited/deleted.
Thank you.

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Chris Warren, be careful not to dissemble. That is why you remain on permanent moderation.

That WHO report webpage you link to has zero mentions of ‘nuclear’ or ‘fallout’ or ‘Chernobyl’ or ‘plutonium’, and one mention of radiation:

(headline) World Cancer Report provides clear evidence that action on smoking, diet and infections can prevent one third of cancers, another third can be cured…

(much deeper down) The report says that the worldwide breast cancer epidemic has many causative factors, including reproductive history, genetics, radiation (especially at times of breast development), and the Western lifestyle with a high caloric diet, obesity and lack of physical activity

That would be mammograms and other medical diagnostics, I suspect. Where is the civilian nuclear industry mentioned? Why did you label your comment “Nuclear toxicity”?


AP 1100 Aircraft impact

What of the common misconceptions as to the shield build of the AP100 in regards to it’s impact characterize appears to me to me a misunderstanding of the purpose of a shield building.

There are many ways to protect something from impact hazard. One is to build them with thick concrete walls, another way is to build them with something that will absorb or some combination of the two.

The shield building on the AP100 doesn’t need to survive an aircraft impact.

It needs to absorb enough energy so that the containment building survives whatever remaining impact energy there is.


harrywr2, on 31 March 2011 at 1:00 PM — Thanks. Is not the outer shield to withstand hurricanes and tornadoes in such a manner that the NPP can be restarted?


re post by: Steve Darden, on 31 March 2011 at 12:01 PM said:

Is this the correct thread for posting Fukushima Daiichi?

Hi Steve,

It is the right thread for any technical discussions. I think hard updates alone still go to the update 26th thread while discussions about various aspects of those updates would be here. The update thread I’m referring to is:

I just wanted to thank you for the posts with links you’ve been posting. That high res video was pretty amazing. Were you able to recognize much beyond the head & crane? Oh, and in one unit I was pretty sure that had to be the empty fuel transfer canal.. It just looked to me as if the roof is covering up almost everything at both units – or at least there is so much rubble I’m assuming that’s what it is….

Then outside one of the buildings there was the large pipe to nowhere, I’ve no idea what that was. I’d think that someone more familiar with actually looking at the refueling floor & with the buildings and layout can probably make more out of it than me by far.


Yeah, hopefully you’re right. The measurements are really very spotty and we don’t much know how they come to the figures and who worked them to the pdf. It was just striking to me there at one moment was measured 13500 times (the Te129/Te129m Bq ratio should be like 694?) more Bq Te-129 than Te-129m -it was the reading I was so amazed with, that I checked the other records. But maybe it is just an error, it would be not the first one there…


Moving post from Philosophical thread per Moderator request… to fill anyone here in who hasn’t been following that thread, a debate started about the robustness of the AP1000 containment, with accusations about how statements to the contrary were unsubstantiated personal opinion – which led to the start of a discussion about licensing, etc. I’ve added the bolding, and snipped out the center bit to shorten it, leaving scope & results sections. Moved post follows:

Rational Debate, on 31 March 2011 at 9:03 AM said:

To those who don’t already realize it, you can find the AP1000 Final Safety Analysis Report and relevant other documentation about the design online wihtout too much trouble.

This stuff isn’t kept secret. The licensing process is extremely in depth and detailed. There are multiple steps, and every bit of the design and all associated assumptions and calculations, materials, etc., are submitted to the Nuclear Regulatory Commission multiple times during that process. At each step NRC then goes over the information with a fine tooth comb, using experts for each area, system, or accident scenario – plus of course a more integrated ‘big picture’ evaluation by experts also. Just go to and you can read up about just what licensing a design entails, and find many of the AP1000 documents too (or links to where you can find them). Any time the NRC has any problem with any aspect, they demand and get either proof from the designer that the design does meet requirements and exactly how it does so, or the designer revises the design until it does meet requirements.

That’s just for the United States – every nation does their own licensing – so to whatever depth each nation goes in licensing a design, the AP1000 has been scrutinized yet again by an entirely new set of experts. As best I know, most use a similar in depth iterative process to design licensing. So anywhere the AP1000 is licensed, it has satisfied large teams of experts that it meets very stringent requirements for function, safety, and so on.

With regard to just how robust the containment design is… here’s a snippet from the AP1000 Probabilistic Risk Assessment Design Control document:




The design of AP1000 takes into account the potential effects of the impact of a large commercial
aircraft. The impacting aircraft analyzed is based upon the impulse time curve provided by the
NRC in July 2007. The impact of a large commercial aircraft is beyond design basis.


The evaluation of plant damage caused by the impact of a commercial aircraft is a complex
analysis problem involving phenomena associated with structural impact, shock-induced
vibration, and fire effects. The analysis of the aircraft impact considers structural damage, such as
that caused by the penetration of hardened components (e.g., engine rotors, landing gear).

An assessment of the effects of aircraft fuselage and wing structure is performed.

An assessment of the effects of shock-induced vibration on systems, structures, and components is

An assessment of the penetration of hardened aircraft components, such as engine rotors and
landing gear is performed.

Perforation of analyzed structural components is not predicted; therefore, realistic assessments of
the damage to internal systems, structures, and components caused by 1) burning aviation fuel and
2) secondary impacts are not required.

{snipped for brevity}



The AP1000 Aircraft Impact Assessment is detailed in Technical Report APP-GW-GLR-126
(Reference 1). The assessment concludes that AP1000 can continue to provide adequate
protection of the public health and safety with respect to aircraft impact
as defined by the NRC.
The aircraft impact would not inhibit AP1000’s core cooling capability, containment integrity,
spent fuel pool integrity, or adequate spent fuel cooling based on best estimate calculations.

The assessment resulted in the identification of the following design features and functional
capabilities; changes to which are evaluated and reported in accordance with 10 CFR 50.150(d).


Shield Building

The shield building as described in Section 3H and Figure 3.7.2-12 (Sheets 7, 8, and 9) is a key
design feature for the protection of the safety systems located inside containment from the impact
of a large commercial aircraft. The assessment detailed in Reference 1 concludes that a strike upon
the shield building would not result in the penetration of the containment vessel such as to cause
direct damage or exposure to jet fuel of the systems or equipment within the containment vessel.

The location of key safety-related components inside containment, including the reactor pressure
vessel, steam generators, and reactor coolant loop, was analyzed to show that structural integrity
was maintained as a result of shock-induced vibrations resulting from the impact of a large
commercial aircraft. The assessment detailed in Reference 1 concluded that the loads induced by
the impact of a large commercial aircraft are enveloped in all situations by the forces for the safe
shutdown earthquake.


This is very interesting about the AP1000 and the end with the earthquake is illustrative. I would think any earhquake above say 5.5M is more energy coupled to the containment building than a jetliner impact. Yet all the nuke plants in Japan survived it. Problem at Fukushima was the tsunami, which I think will have way higher impact momentum than a jetliner.


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