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Fukushima Nuclear Accident – 16 March update

This is an update of the situation as of 10 am JST Wednesday 16 March. (For background on events of 15 March and earlier, start with this post and its included links.) Note that this is a blog, not a news website, and thus the following analysis, like all others on BraveNewClimate, is a mixture of news and opinion — but facts remain paramount.

First, the situation is clearly (but slowly) stabilising. As each day passes, the amount of thermal heat (caused by radioactive decay of the fission products) that remains in the reactor fuel assemblies decreases exponentially. When the reactors SCRAMed on 11 March after the earthquake, and went sub-critical, their power levels dropped by about 95 % of peak output (the nuclear fission process was no longer self-sustaining). Over the past 5 days, the energy in the fuel rods dropped by another ~97 %, such that the heat dissipation situation is getting more and more manageable. But we’re not out of the woods yet, and the reactor cores will need significant cooling for at least another 5 days before stability can be ensured.

Yesterday there appears to have been a fracture in the wetwell torus (see diagram: that circular structure below and to the side of the reactor vessel) in Unit 2, caused by a hydrogen explosion, which led to a rapid venting of highly radioactive fission product gases (mostly noble [chemically unreactive] gases, the majority of which had a half-life of seconds to minutes). It also caused a drop in pressure in the supression pool, which made the cooling process more challenging. However, despite some earlier concerns, it is now clear that containment was not breached. Even under this situation of extreme physical duress, the multiple containment barriers have held firm. This is an issue to be revisited, when the dust finally settles.

Units 1 and 3, the other two operating reactors at Fukushima Daiichi when the earthquake struck, continue to be cooled by sea water. Containment is secure in both units. However, like Unit 2, there is a high probability that the fuel assemblies have likely suffered damage due to temporary exposure (out of water), as the engineers struggled over the last few days to maintain core coolant levels. Whether there has been any melting of the clad or rods remains unclear, and probably will continue to be shrouded in a cloud of uncertainty for some time yet.

The other ongoing serious issue is with managing the heat dissipation in the spent fuel ponds. These contain old fuel rods from previous reactor operation that are cooling down, on site, immersed in water, which also provides radiation shielding. After a few years of pond cooling, these are transferred to dry storage. The heat in these rods is much less than those of the in-core assemblies, but it is still significant enough as to cause concern for maintaining adequate coverage of the stored fuel and to avoid boiling the unpressurised water. There have been two fires in Unit 4, the first tentatively linked to a failed oil pump, and the second, being of (currently) unknown cause, but the likelihood is that it was linked to hydrogen gas bubbling.

There appears to have been some exposure of this spent fuel, and radiation levels around this area remain high — making access in order to maintain water levels particularly troublesome. Note that apart from short-lived fission product gases, these radiation sources are otherwise contained within the rods and not particularised in a way that facilitates dispersion. Again, the problems encountered here can be linked to the critical lack of on-site power, with the mains grid still being out of action. As a further precaution, TEPCO is considering spraying the pool with boric acid to minimise the probability of ‘prompt criticality’ events. This is the news item we should be watching most closely today.

An excellent 2-page fact sheet on the spent fuel pool issues has been produced by the NEI, which can be read here: Used Nuclear Fuel Storage at the Fukushima Daiichi Nuclear Power Plant (this includes an explanation of what might happen under various scenarios).

This figure illustrates the current reported state of the Daiichi and Daini reactors, last updated 1230 on 16 March (click to enlarge):

The status report from the The Federation of Electric Power Companies of Japan (FEPC) is given below:

• Radiation Levels

o At 10:22AM (JST) on March 15, a radiation level of 400 milli sievert per hour was recorded outside secondary containment building of the Unit 3 reactor at Fukushima Daiichi Nuclear Power Station.

o At 3:30PM on March 15, a radiation level of 596 micro sievert per hour was recorded at the main gate of Fukushima Daiichi Nuclear Power Station.

o At 4:30PM on March 15, a radiation level of 489 micro sievert per hour was recorded on the site of the Fukushima Daiichi Nuclear Power Station.

o For comparison, a human receives 2400 micro sievert per year from natural radiation in the form of sunlight, radon, and other sources. One chest CT scan generates 6900 micro sievert per scan.

• Fukushima Daiichi Unit 1 reactor

o As of 10:00PM on March 14, the pressure inside the reactor core was measured at 0.05 MPa. The water level inside the reactor was measured at 1.7 meters below the top of the fuel rods.

• Fukushima Daiichi Unit 2 reactor

o At 6:14AM on March 15, an explosion was heard in the secondary containment building. TEPCO assumes that the suppression chamber, which holds water and stream released from the reactor core, was damaged.

o At 1:00PM on March 15, the pressure inside the reactor core was measured at 0.608 MPa. The water level inside the reactor was measured at 1.7 meters below the top of the fuel rods.

• Fukushima Daiichi Unit 3 reactor

o At 6:14AM on March 15, smoke was discovered emanating from the damaged secondary containment building.

• Fukushima Daiichi Unit 4 reactor

o At 9:38AM on March 15, a fire was discovered on the third floor of the secondary containment building.

o At 12:29PM on March 15, TEPCO confirmed extinguishing of the fire.

• Fukushima Daini Units 1 to 4 reactors: all now in cold shutdown, TEPCO continues to cool each reactor core.

This indicates a peak radiation level of 400 mSv/hr, which has come down to about 0.5 mSv/hr by the afternoon. This ‘spot’ radiation level was measured at a location between Unit 3 and 4. It was attributted to a hydrogen explosion in the spent fuel pool of Unit 4 — but this is still under debate. The radiation level at the site boundary is expected to have been much lower and, to date, there is no risk to the general public.

Two other useful sources of information are from the WNN: Radiation decreasing, fuel ponds warming and Second fire reported at unit 4. ANS Nuclear Cafe continues to be a great collator of key official channels and top news stories.

Finally, this is a useful perspective from an MIT staffer that is well worth reading:

What happened at the Fukushima reactor? Events in Japan confirm the robustness of modern nuclear technology — not a failure

Kirk Sorenson, from Energy from Thorium blog, also has this very interesting piece: Thoughts on Fukushima-Daiichi. A concluding excerpt:

What is known is that this is a situation very different than Chernobyl or Three Mile Island. There was no operator error involved at Fukushima-Daiichi, and each reactor was successfully shut down within moments of detecting the quake. The situation has evolved slowly but in a manner that was not anticipated by designers who had not assumed that electrical power to run emergency pumps would be unavailable for days after the shutdown. They built an impressive array of redundant pumps and power generating equipment to preclude against this problem. Unfortunately, the tsunami destroyed it.

There are some characteristics of a nuclear fission reactor that will be common to every nuclear fission reactor. They will always have to contend with decay heat. They will always have to produce heat at high temperatures to generate electricity. But they do not have to use coolant fluids like water that must operate at high pressures in order to achieve high temperatures. Other fluids like fluoride salts can operate at high temperatures yet at the same pressures as the outside. Fluoride salts are impervious to radiation damage, unlike water, and don’t evolve hydrogen gas which can lead to an explosion. Solid nuclear fuel like that used at Fukushima-Daiichi can melt and release radioactive materials if not cooled consistently during shutdown. Fluoride salts can carry fuel in chemically-stable forms that can be passively cooled without pumps driven by emergency power generation. There are solutions to the extreme situation that was encountered at Fukushima-Daiichi, and it may be in our best interest to pursue them.

More updates as further information comes to hand. Otherwise, for me, it’s back to the mad TV and radio media circus.

UPDATE: From World Nuclear News: Problems for units 3 and 4

Chief Cabinet Secretary Yukio Edano had outlined problems that had occured on the morning of 16 March with Fukushima Daiichi 3 and 4.

At 8:34am local time white smoke was seen billowing out of Fukushima Daiichi 3. Efforts to determine the cause of this development were interrupted as all workers had evacuated to a safe area due to rising radiation readings. Readings from a sensor near the front gate had fluctuated for some time, although Edano said that on the whole there was no health hazard. Earlier in the morning readings had ranged between 600-800 microsieverts per hour, but at 10am readings rose to 1000 microsieverts per hour. Readings began to fall again from around 10:54.

Edano said that one possibility being considered was that the unit 3 reactor had suffered a similar failure to that suffered by unit 2 yesterday, although there had been no reported blast or loud sound, which had been the case for unit 2. The immediate focus, said Edano was on monitoring of levels and checking pumping operations.

Edano also outlined plans for units 4-6. Preparations were being made to inject water into unit 4, however the high levels of radiation from unit 3 were imparing those preparations. When possible, the water injection would be done gradually as there were safety concerns over pouring a large amount of water at once. The water will be pumped into the reactor building from the ground, plans to drop water from a helicopter having been abandoned. Although he said that “all things were possible” Edano did not believe that recriticality at unit 4 was a realistic risk

Second fire at unit 4

Earlier, the Nuclear and Industrial Safety Agency said that a blaze was spotted in the reactor building of Fukushima Daiichi 4 at 5.45am local time this morning.

Attempts to extinguish it were reportedly delayed due to high levels of radiation in the area. A spokesperson for TEPCO said that by around 6:15am there were no flames to be seen.

The incident at unit 4 is believed to be in the region of a used fuel pond in the upper portion of the reactor building.

Origins

Tokyo Electric Power Company issued a notice of an explosion at unit 4 at 6am on 15 March. This was followed by the company’s confirmation of damage around the fifth floor rooftop area of the reactor building.

On that day, a fire was discovered but investigations concluded it had died down by around 11am.

At present it is not clear whether today’s fire was a completely new blaze, or if the fire reported yesterday had flared up again.

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.

485 replies on “Fukushima Nuclear Accident – 16 March update”

@Jeff: it’s really hard to get any serious estimate on (re)criticality because the status and topography of the cores is not precisely known.

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William

it appears that the ECCS went down on the 12th but they were able to repair it and get it operational again.

I’m wondering if the fact Dai-ni was commisioned in 1984, had anything to do with it.

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re: Jaczko

If you wanted to aggravate the potential for panic what you’d do first, after tolerating the exaggerated uberhyped concern for radiation you knew made no sense all these years, is undermine the confidence of the population in Japan in the statements and abilities of their own officials and engineers.

After this is over we’ll find out if the Americans are right. Even if the NRC assessment is the correct one what did he contribute to the situation by making his views public before convincing the Japanese leadership?

A commenter at Rod Adams blog, “Rich” says this: “Are you aware of the fact that the whole “hydrogen bubble” hysteria at TMI was caused by an NRC “engineer” (in headquarters, not at the site) that used the conversion factor for English/metric backwards? He was “checked,” etc., by other NRC engineers and thus they firmly believed in their conclusion. Meanwhile, we at TMI spent three days trying to convince the NRC that something was wrong with their calculations. We finally came up with the simple equation PxV=PxV (any basic chemistry student understands that) and after a series of pressure changes we provided the proof that the “bubble” in the core was of no concern. By then, evacuation orders were issued, people panicked, etc, etc, etc. Of course, the responsible NRC engineer was promoted, and now you know the rest of the story. How much of that is going on now? (I know – I was there and have the T-shirt to prove it)”

Its one thing for the NRC to blunder around on their own territory, but to wade into the middle of this crisis as Jaczko has done with his Congressional testimony seems tragic.

There is a very good possibility that the NRC does not have any on the ground insights in this case. The spent fuel pool for unit 4 was reported to be at 183 degrees and full on March 15. Where did 23 feet of water above the 14 foot long fuel assemblies go?”
[ ad homs removed]

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@David Lewis, on 17 March 2011 at 12:25 PM said:
re: Jaczko

Exactly right. Every time I hear someone making comments I look them up via google. By and large they are poli-sci majors. In this case he has a legitimate degree, but if you review his politics and what he has done since getting his degree you come to the conclusion he’s a bomb thrower.

I suggest we check on every person with an opinion and check their background and political persuasion.

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Radiation levels at plant perimeter, Mar10 to Mar 16: http://graphics8.nytimes.com/packages/images/newsgraphics/2011/0316-japan-quake-radiation/0317-web-RADIATION.jpg

Highest values to date during I-4 SFP fire: c.12 mSv/h at perimeter, 400 mSv/h between I-3 and I-4 reactor buildings.

This should put the loads of values from all sorts of measuring sites into perspective. With the data above and the date/time, you can now make a good guess where a particular measurement was taken exactly (perimeter, close to reactor buildings, inside reactor buildings).

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Yes I don’t understand the temperture readings from IAEA and the claims that the spent fuel ponds are dry. But there is a lot of effort to refill them and JAIF reports low water level on 3 and 4 and suspected fuel damage. I find the same reading on both days not credible for unit 4. The temperature should have been rising. No data at all for units 1 and 2. Why?

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In addition to the Mar18 JAIF update, supposedly dropping water level in I-5 SFP.

Did anyone also note that the I-2 pressure vessel pressure monitor is down?

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@william: a lot of monitoring equipment is unlikely to be still working as intended. Also the IAEA has been complaining for days that TEPCO is anything but forthcoming with data.

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@David Lewis “There is a very good possibility that the NRC does not have any on the ground insights in this case”

“The information that we have is coming from staff people that we have in Tokyo who are interfacing with counterparts in the nuclear industry in Japan, and I’ve confirmed with them that they believe the information they have is reliable,” Jaczko told ABC News.

“We believe that there is no water in the spent-fuel pool known as No. 4, and I would say that it is my great hope that the information that we have is not accurate,” he added.

from http://www.politico.com/news/stories/0311/51456.html#ixzz1GosUEoN2

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@evnow

‘They need to stop pulling out people—and step up with getting them back in the reactor to cool it. There is a recognition this is a suicide mission,” the official said.’

Is this really what the US government thinks ?
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That’s a really bad quote, the part about “suicide mission”. ALARA, “As Low As Reasonably Achievable” still applies. They’re doing a great job managing a difficult circumstance. But its not a suicide mission.

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evcricket said:

“Barry, aren’t these sentences contradictory?:

Yours:’Even under this situation of extreme physical duress, the multiple containment barriers have held firm.’

‘• Fukushima Daiichi Unit 3 reactor

o At 6:14AM on March 15, smoke was discovered emanating from the damaged secondary containment building.’”

I think you misunderstand the terminology –

containment building= the outer building (as in the walls of a room)

containment barriers=the stainless steel reactor container and the concrete surrounding that.

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@evnow: Presumably. “Needs to” is not something used carelessly in diplomatic language, let alone to an allied country.

US tone has become decidedly aggressive in the last 24 hours.

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William Fairholm, on 17 March 2011 at 12:46 PM — I will hazard the guess that the pools of units #1 and #2 contain no fuel rods. For unit #1 this makes sense since it was due to be decommisioned later this month and so had already received its final refueling some time ago. For unit #2, one might check for something similar.

Certainly not definitive on my part.

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@Paul

“ew-3: a scientific question must not be decided based on someone’s persuasion, but on their data.”

Absolutely right. I’d like to hear the data the had the head of our NRC had.

Odds are he had no data.

Once you get inside the beltway facts become secondary. He moves ahead in his career by closing down nuclear as an option. (Google him and you’ll see what I mean). I grew up in the 1950s/60s when we made stuff happen.

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@David B. Benson: Spent fuel from 30 years of operations has been stored where?

Japanese practice is apparently to keep them in the reactor SFPs until Rokkasho was working.

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Paul, on 17 March 2011 at 1:07 PM — Actually 40 years of operation. There is a joint dry cask facility on the site.

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@Paul

NRC has supposedly 2 scientists on scene. (According to my knowledge, this *may* be 2 more than IAEA has)

What two scientists and where are they and what have they really seen. Facts!

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Problems with seawater corroding emergency pumps, but didn’t catch on which reactor.

Confirmed that SFP water level is dropping in I-5 and temp is rising.

Source: NRC live

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Paul, on 17 March 2011 at 1:18 PM said:
“Maximum radiation levels per perfecture”

I can’t understand these numbers. They are in nanoGrays/hr? Some of the numbers seem too low for even natural background.

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The reason they concentrated on I-3 is that yesterday there was still water in the SFP, with no data suggesting this has changed yet. Whereas in I-3 the SFP water seems to have boiled off for the most part. But due to the wreckage it is hard to tell. (source: NHL)

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“Therefore once it was known reactors OK after quake, but no power after tsunami, would it not have been an idea to restart one reactor so as to provide power to the whole complex? Surely this could have kept all the cooling going and prevented many if not all the problems now faced?”

I like your way of thinking, it is “outside the box” so to speak. But the pumps, controls, valves, etc. required to produce power but which do not serve a safety purpose cannot operate unless mains or local generator power is already available. They draw a lot of energy and would not be powered by the batteries. Also, there is a good chance that circulating water pumps for the turbine condensers were located near the ocean and damaged by the tsunami.

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@bryen yep, the New Matilda version of Green’s ‘contribution’ is very nearly identical to what appeared earlier on Unleashed and OLO.

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re: suicide missions.

Asahi Japan Watch Senior Staff Writer Keiji Takeuchi posted this on his Facebook Wall:

<a href=hthis new article.>tCommentary: Time for Decisive Action at Fukushima.

“…Japan now faces a question that has been taboo since the Chernobyl nuclear accident in 1986, namely, who has to step up and do the work to mitigate a high-radiation nuclear accident”

He writes that the topic came up in Japan after everyone saw the sacrifice of the Chernobyl “heroes”. He notes the debate “faded because it would have involved the fundamental social issue of whether a democratic state can order people to do work harmful to their health.”

“There was also the myth that major accidents just do not happen in Japan.

Now, however, we face an emergency situation. A quick decision and response is required.”

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It seems that somewhere there is a report confirming water in #4 cooling pond as of yesterday (Wednesday in Japan). Sorry I don’t have a link.

Is this correct?

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Answering my own question, on the redux thread apeescape, on 17 March 2011 at 2:03 PM, describes, indicating the situation is as I stated.

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Looking at the helicopter, comparing the water pattern to what you see from firefighting operations, they’re making a fairly high speed pass across the top of the reactor building. It must be very hot.

This is where we need the damn robots. One to hover the helicopter with the huge bucket of water, or lower it right through the roof; the other to rappell down, put the hose in the pool, tie it down, and signal to start draining the bucket through the hose.

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Sakei: according to TEPCO first helicopter drop a failure
(Having seen the video, it is obvious that most of the water didn’t go where intended)

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@Hank: the technology you describe does neither exist, nor would it work reliably under these conditions anyway.

From the TEPCO reports on I-4 SFT water level (it can be verified but neither regularly or at will; it is more like chance observations) and ceiling status (now reported as having been collapsed), it is obvious that the SFT floor is full of debris.

Add to that radiation levels which will make short work of unshielded electronics. Shielding makes a RC vehicle heavier, bulkier and harder to control.

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The US federal government military R&D budget is around $80 billion a year, with Health R&D at $27 billion plus. R&D for those robots that could be delivering water to those pools right now might have amounted to a rounding error in the military R&D.

It used to be said of Japan that they had more robots working in industry than any other country.

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@David yes if anyone had such machinery, it would be Japan. But even Japan is still bound by the usual laws of physics. Conservation of momentum, conservation of energy. These are the two bad guys in this case, and have been from the start.

But they won’t ever go away. Not in this universe they won’t. No matter how much money you throw at them. Fundamental laws of nature cannot be bought or bribed.

It is actually rather simple:
Before there will be a single robot/RC vehicle for NPP rescue work, there will be thousands for nonnuclear rescue work, e.g. after earthquakes, tsunamis…

Presently there are about zero of the latter in use, hence there are also zero of the former to use.

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D.F:

Black start of a unit in order to run the others would require about 10MW, perhaps more. Batteries, etc, are OK for run-down but useless for startup.

Put bluntly:
1. A unit cannot be started without connection to the grid to provide start-up power for auxiliaries – fans, pumps, computers, miscellaneous power and lighting, and instrumentation and control systems.
2. To keep a unit running requires a connection to the grid, which provides sufficient stable load for the unit to work with. An adjacent nuclear power plant or three would not provide an adequate load, even if switching and conductors could be arranged, which I doubt.

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@Paul, 17 March 2011 at 2:36 PM:

Having worked with choppers many times in bushfires, I have found that some pilots are very good at swinging their bucket to a halt, right over the target, while others are far less accurate.

Those guys on the video are way up high, I assume not due to temperature, but to put a bit of distance between their body and radiation sources.

No surprise… most of their payloads of water can be expected to fall wide of the target.

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As a sanity check, here are some claims excerpted from the parallel discussion over at BoingBoing:

Brace yourself:

If that sounds like a design flaw, you’re right. The Fukushima reactors were built in the early 1970s. In modern nuclear reactor designs, pumps aren’t necessary to move water through the core in an emergency shut down. Instead, the water moves via gravity.

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. Like Maggie said, these are a 1970’s design. Chernobyl in 1986 made everyone fundamentally change their plant design so that in the event of a failure, or a problem, the system cools itself. Since then, Reactors are made to always run on the ‘cool’ side of their reactions and the human intervention is to keep them ticking over. This is very important to consider when talking about say, new nuclear power plants being built – for example nobody would but a boiling water reactor these days.
Like Maggie said the coolant is ideally gravity-fed rather than pumped, so if anything goes wrong the coolant still flows down and it all works. From
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Actually unattended nuclear power plants, assuming they don’t get flooded like the Japanese reactor, will eventually just shut themselves down. A couple of things happen.

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I could go on and on, but am already making this more complicated than most people care to deal with.
Oh, as a side note to someone else’s comment, control rods slowly change into atoms or isotopes that don’t absorb neutrons. So if not maintained, eventually a reactor core will heat enough to melt down.
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wow! this is an awesome explanation!

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All modern reactors come with automatic shutdown mechanisms when there is a problem. But they are pretty good at running themselves, so what would more likely happen is that they would operate until they ran out of fuel and shut down when there was no one around to refuel (like a car running out of gas, it would just putter to a stop).
Modern reactors also are designed such that they will shut down in the event of loss of coolant (albeit this can take some time when you’re at the GW+ scale), and have a maximum achievable power. This is guaranteed by the laws of physics in what is called a “negative temperature coefficient” if you want to look up the details.
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That was the shortest, clearest explanation I could even imagine. Thanks for the info, but more than that, thanks for putting my mind at ease. Now at least I’ll know how to interpret the stories that follow.

============

aieeeee…..

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Voice of America reporter Steve Herman in Koriyama: 25 Bq on skin, 50 Bq on shoes. Another reporter: >150 Bq on shoes.

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NHK reports 14 deaths during evacuation due to insufficient medical supplies. I have also seen reports of “another explosion at I-4” supposedly on NHK, but there was no mention of it on the program so I supposed it was referring to past events.

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What was the thinking behind putting several reactors together like this? Could it not have been foreseen that if one goes into a state that makes the facility unapproachable, then the rest of the plant can’t be looked after. If one explodes for whatever reason it might damage another reactor. It all seems like the temptations of nuclear mist the glasses of those who should know better. I am of limited education and it seems like a no brainer thought.

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In the JAIF pdf listed above by chavv, the main change from the last is that they are now listing the Reactor Pressure Vessel Integrity as unknow for units 1-3. Radiation levels at the NPS border has fallen again, which is good, but they must be fluctuating quite a bit with just wind patterns is I don’t know what to make of a single number given every 8 hrs or so.

This is yesterday’s summary. For more info move to today’s.

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i deeply pray for their victory there at the plant.

NHK reports they managed to spray water but still the temps in pools of #3 and 4 reactors are increasing.

” The forces finished the 30-minute operation on Thursday evening. Five fire engines loaded with a total of 30 tons of water were used.

But the Defense Ministry says it has not confirmed whether the water reached the storage pool housing spent fuel rods, though it reached the inside of the building that houses it.

The forces are preparing to repeat the exercise on Friday if requested by the government.

Temperatures are rising in the spent fuel rod pools of the plant’s No.3 and No.4 reactors, where a massive radiation leakage is feared.

Earlier in the day, police also used high-pressure water canons to douse the No.3 reactor from the ground. But the water failed to reach the target, and the operation was suspended due to high radiation levels.

Thursday, March 17, 2011 22:14 +0900 (JST) “

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Are there no gasoline driven pumps at the major Japanese steel mills in the south that can be airlifted to the site? There’s gotta’ be some pumps somewhere that aren’t electrical driven. Even some small trash pumps would add more water than those chopper drops – that mostly miss the target!

Please!! Kobe, Sumitomo, Nippon, Aichi, or Kawasaki – get these workers some pumps !!!

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I read that they still need to get electrical power to the pumps.. after all this time, why has no one has bothered to bring large generators to the site?

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How can they be sure that even with a new power feed those tsunami-hit pumps and the connections and level 2 controls will even work ? Who is developing some contingency plans with air lifts of replacement or alternate pumps? After four attempts – this is starting to look like a 3-ring circus.

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Settle down, Steel Engineer.

The configuration of the 13 diesel generators is not known, neither is the configuration of individual pump sets.

I imagine that, as suggested by the fact that one generator will alternately enable running of Unit 5 and 6 auxiliaries, there is only limited flexibility.

In other words, for any given unit, there may be two dedicated generators and only a small number of options re pumps. Not everything is manifolded to everything else.

Your questions are basic and appropriate, but I suspect that the options and constraints are much more complex and limiting.

In short, I think that the Japanese engineers are at least as adaptable and knowledgeable as you, me or any other experienced engineer.

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“… On Wednesday, when the American Embassy in Tokyo, on advice from the Nuclear Regulatory Commission, told Americans to evacuate a radius of “approximately 50 miles” around the Fukushima plant, the recommendation was based on a specific calculation of risk of radioactive fallout in the affected area.

In a statement, the commission said the advice grew out of its assessment that projected radiation doses within the evacuation zone might exceed one rem to the body or five rems to the thyroid gland. That organ is extremely sensitive to iodine 131 — another of the deadly byproducts of nuclear fuel, this one causing thyroid cancer.

The commission says that the average American is exposed to about 0.62 rem of radiation each year from natural and manmade sources.

The American-provided instruments in Japan measure real levels of radiation on the ground. In contrast, scientists around the world have also begun to draw up forecasts of how the prevailing winds pick up the Japanese radioactive material and carry it over the Pacific in invisible plumes.

Private analysts said the United States was also probably monitoring the reactor crisis with spy satellites that can spot the heat from fires — helping it independently assess the state of the reactor complex from a distance. …”

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from the BBC site:” Japan has started using a cooling pump at the Fukushima plant’s stricken reactor 5, according to several reports quoting the Japanese government. It is thought to be a diesel-powered pump, rather than a device powered by the still-to-be-reconnected electricity supply.”

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