Japan quake, tsunami, nuke news 15: Water leaking into sea via crack, and concerns over hydrogen buildup

i-56d9c13b4cea955a375fea272b817891-CRACK15964750-thumb-250x334-63383.jpgDespite the deafening silence from TEPCO regarding questions over a physical breech in Reactor 2, it is now generally being considered that there is a breech in reactor 2. It is not clear if it is a hole in the containment vessel of some kind or just some disconnected or cracked pipes. Experts are estimating the percent of fuel in the reactors that were active at the time of the quake that has been damaged as fairly high (over half). The most significant news over the last several hours is probably the identification of a major route by which radioactive water is leaking from Reactor 2 into the sea. This is a 20 cm wide crack in the concrete foundation of the reactor building. TEPCO claims that it will fill the crack with concrete.

It also appears that there are raised concerns about hydrogen buildup in reactors 1 and 2, and efforts are being made to avoid an explosion from this hydrogen.

We have not heard a lot about Reactors 5 and 6 because they were not in operation at the time of the earthquake and tsunami, so the situation has not been particularly tricky there, but there is a development there now. Both buildings have spent fuel pools and though the cooling systems there are said to be working there is concern over the ability to keep these fuel rods cool over the short to medium term future. If they heat up it is possible to get hydrogen buildup which could cause an explosion in the building containing the reactors. To avoid this, holes have been punched in the structures covering reactors 5 and 6.

Some experts assert that the chance of fuel undergoing significant fission beyond what is happening now, which might damage containment vessels and cause more radiation escape, as non-trivial in the short to medium term future.

Ana's Feed:

April 1, 8PM

Three of the six reactors at the Fukushima Daiichi nuclear power plant experienced a jolt stronger than a worst case projection when hit by Japan's largest-ever earthquake March 11, provisional data by the operator Tokyo Electric Power Co. showed Friday. -kyodo news

  • The data suggest that the intensity of the strongest earthquake projected could have been underestimated. The nuclear safety agency stopped short of describing the finding as a problem but urged the utility to analyze it in detail. -kyodo

April 2, 3 AM

"A Japanese government official told Kyodo News it has been confirmed that water with high levels of radiation has seeped into the sea from the No. 2 reactor..." (Efforts to remove tainted water continue...)

Checking if tainted water from other reactors seeping into sea -kyodo news
Analiese Miller
â"Tokyo Electric Power Company says it has found that radioactive water is leaking into the ocean from a 20-centimeter crack in a facility wall of the No.2 reactor at the Fukushima Daiichi nuclear power plant.
The power company said on Satur...day that the level of radiation has been measured at over 1,000 millisieverts per hour." (NHK)
Video report

"The Joint FAO/IAEA Food Safety Assessment Team has completed its mission and presented its report to the Japanese Cabinet Office, Ministry of Foreign Affairs, Ministry of Health, Labour and Welfare and the Ministry of

Agriculture, Fisheries and Forestry on 31 March. The IAEA members of the Team are returning to Vienna today." -from IAEA update for April 1

TEPCO says it will make radiation levels available on its website. -NHK

SDF aircraft used in the operations around the plant have become highly contaminated - cesium adheres to the paint. The gov. is looking into the purchase of special equipment for decontamination, and is advising mechanics to take precautions. -NHK

News stories and updates:

Fukushima crack to be entombed

A crack in the foundation of the Fukushima-1 nuclear power plant's second reactor is being entombed in concrete to prevent radioactive water from flowing out into the sea.

According to estimates, radiation levels in the area are almost 5,000 times above normal.

New leak found at Japan nuclear plant

"Fukushima disaster worse than Chernobyl"

Russian nuclear energy expert Natalia Mironova says that Fukushima disaster is "much bigger than Chernobyl."

the Russian nuclear energy expert has assessed that Japan's unfolding nuclear disaster is "much bigger than Chernobyl" and could rewrite the international scale used to measure the severity of atomic accidents.

"Chernobyl was a dirty bomb explosion. The next dirty bomb is Fukushima and it will cost much more" in economic and human terms, Mironova was cited by the agencies.

Mironova is a thermodynamic engineer who became a leading anti-nuclear activist in Russia in the wake of the accident at the Soviet-built reactor in Ukraine in 1986.

Fukushima Nuclear Reactor Truth: Locally Chernobyl

For decades we have been told that with the lessons learned from the 1986 Chernobyl disaster, nuclear energy is safe. As the still unfolding mayhem at the Dai-Ichi plant in Fukushima, Japan, proves, nothing could be further from the truth.

Atomic Snowflakes

Only two U.S. nuclear sites are in compliance with federal fire regulations. How confident can we be that the Nuclear Regulatory Commission has things firmly in hand?

After Fukushima, The 'Nuclear People' Emerge

At the damaged Fukushima complex, officials say radioactive water is leaking into the ocean, but it is expected to be quickly diluted. Japan's Kan visits a tsunami-stricken town.

Nuclear's green cheerleaders forget Chernobyl at our peril

The authorities reassure us by saying there is no immediate danger and a few absolutist environmentalists obsessed with nuclear power because of the urgency to limit emissions repeat the industry mantra that only a few people died at Chernobyl - the worst nuclear accident in history. Those who disagree are smeared and put in the same camp as climate change deniers.

I prefer the words of Alexey Yablokov, member of the Russian academy of sciences, and adviser to President Gorbachev at the time of Chernobyl: "When you hear 'no immediate danger' [from nuclear radiation] then you should run away as far and as fast as you can."

Current International Atomic Energy Agency briefing:

On Saturday, 2 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1.Current Situation

Overall at the Fukushima Daiichi plant, the situation remains very serious.


(Click here for the full IAEA presentation graphic)

In preparation for transferring water in the basement of the Unit 1 turbine building to the condenser, water in the condenser storage tank is being transferred to surge tank of the suppression pool since 31 March 03:00 UTC. Water in the trench was transferred to a water tank at the central environmental facility main building. The water level in the trench was reduced by 1 metre to 1.14 metre below the top of the trench on 31 March. On Unit 2 in order to prepare for removal of the water from turbine building basement, pumping of water from the condenser to suppression pool water surge was started 29 March 07:45 UTC and was finished 1 April 02:50 UTC. On Unit 3 in order to prepare for removal of the water from turbine building basement, pumping of water from the condenser to suppression pool water surge was started 28 March 08:40 UTC and completed 30 March 23:37 UTC.

In a press release on the 2nd April NISA reported the following. Water with dose rate of greater than 1000 millisievert/hr was confirmed by TEPCO at around 00:30 UTC on 2nd April in a pit housing cables located next to the Unit 2 sea water inlet point. There exists a crack on the sidewall of the pit, about 20cm in length, and water inside the pit is confirmed to be leaking directly to the sea. The isotopic analysis of water samples from inside the pit, the sea and near the seawater inlet bar screen filter is in process. Currently a plan to patch the pit with concrete is underway to stop the leakage. An investigation on the leakage path to this pit is on-going and measures to stop leakage to the sea will be implemented.

Transfer of fresh water from a US Navy barge to the 'filtered water tank' started on 1 April 06:58 UTC, and was suspended on 1 April 07:25 UTC due to a connection failure. A second US Navy barge left Onahama port and planned to arrive 2 April 00:30 UTC.

On Unit 1 fresh water has been continuously injected into the reactor pressure vessel through the feed-water line at an indicated flow rate of 8 m3/h using a temporary electric pump with diesel backup. The indicated temperature at the feed water nozzle of the RPV has decreased from 256 °C to 249 °C and at the bottom of RPV decreased from 128 °C to 119 °C. There was a corresponding decrease in RPV pressure and Drywell pressure.

Fresh water is injected continuously through fire extinguisher line on Unit 2 at an indicated rate of 9 m3/h using a temporary electric pump with diesel backup. The indicated temperature at the feed water nozzle of the RPV has decreased from 165 °C to 161 °C. The temperature at the bottom of RPV was not reported. Indicated Drywell pressure remains at atmospheric pressure.

On Unit 3 Fresh water is being injected continuously at an indicated rate of 7 m3/h into the reactor core through the fire extinguisher line using a temporary electric pump with diesel backup. The indicated temperature at the feed water nozzle of the RPV is about 119 °C and at the bottom of RPV is about 90 °C.

Fresh water (90 T) was pumped into the spent fuel pool in Unit 1 using a concrete pumping truck on 31 March. In Unit 2, injection of water into spent fuel pond using the temporary pump was restarted on 1 April 05:56 UTC. Fresh water (180 T) was pumped into the spent fuel pool on Unit 4 using a concrete pumping truck on 1 April.

Units 5 and 6 remain in cold shutdown with plant systems operating on off-site AC power.

2. Radiation Monitoring

On 1 April, deposition of iodine-131 was detected in 7 prefectures ranging from 7 to 74 becquerel per square metre. Deposition of cesium-137 in 9 prefectures was reported on April 1st ranging from 2.9 to 76 becquerel per square metre. Reported gamma dose rates in the 45 prefectures showed no significant changes compared to yesterday.

The Ministry of Agriculture, Forestry and Fisheries of Japan informed the IAEA that, because of winter conditions, most cattle, pigs and chickens are presently kept indoors. Animals are primarily fed on stored dried grass, silage and grain that has not been contaminated by the releases from the Fukushima Daiichi NPP.

On 31 March, NISA reported that among the workers at the Fukushima Daiichi plant, 21workers have received doses exceeding 100 mSv. No worker has received a dose above 250 mSv, which is the dose limit for emergency workers.

On the 30 March, 180 000 Bq/l of I-131 and 15 000 Bq/l of Cs -137 were detected in the vicinity of the discharge water outlet of Unit 4.

The data reported for 27th - 30th March indicated that the levels at 30 m from the common discharge point of Units 5 and 6 were relatively constant at 45 000 - 55 000 Bq/l for I-131 and 10 000 - 15 000 Bq/l for Cs-137.

In addition to the 8 sampling points 30 km from the coast two additional monitoring stations were added in the South, 10km and 20 km from shore. The values reported for 28 and 30 March indicate a non-uniform distribution and trend.

For more information and essays about the Earthquake, Tsunami and Nuclear Reactor problems in Japan CLICK HERE.


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The blog referenced in comment 1 is not very good. The heat transfer stuff is off, and the decay heat is now much less than it was 3 weeks ago.

It is hard to believe that this crack is only noticed now.

Daedalus2u, I'm really more taken with the overall scenario which he wrote on 15 March. I think it's very close to the mark considering that on that date many thought it was just a few more hours till TEPCO brought in the extension cord and everything would be okay. The details are really not that important, though he was the only person I read who zeroed right in on chlorine when he writes about seawater (in the comments). At that date almost everyone who talked about seawater either focused on corrosion or on sodium-24. Not a big deal.


Casper I don't find it hard to believe at all. Debris is all over the place, it's a big facility, other tasks took higher priority and they didn't even have lighting to see by until recently. This crack is in a structure that shouldn't have water in it in the the first place and being a pit is probably below ground level out of sight. This is the path out to sea but not the source. The most likely source points are not easily physically accessible for any length of time yet. It is going to be a long tedious process to get everything under control.

bks: The chlorine and the corrosion issues are pretty much the same issue. Not sure why the guy necessarily assumes acidic environment, but saltwater is already corrosive with the Cl ion, it does not need to build HCl acid.

Hey, they just found out that concrete doesn't dry if there's permanently water pushing against it.
So they'll now try to fill the crack with polymeres.
How thick are those people and is there still anybody who thinks they are actually handling this responsibly and competently?

Adela, it is outside, and the sun comes up every day even in Japan.There has been unexplained radiation leaking into the sea. The plant is full of water.

All due respect and sympathy to the workers and managers, this looks like something they would have known about and probably did not need to mention until just about now.

Water seeks its own level. Who does TEPCO think it's fooling with this nonsense? They announced finding two dead employees like it was a success story.

They have no idea where to go from here.


Te129 is pretty strong evidence of recriticality, but that is likely a water-moderated criticality which will be self-limiting because the heat will boil water and reduce the moderation.

They need to get more boron in there, but they need to get boron that will stay with the fuel and won't wash out. I suggest adding boric acid solution and calcium acetate solution and mixing them in the reactor so the insoluble calcium borate precipitates out on hot things, like fuel. They should add some solid particles of a boron containing material, like pyrex or boron carbide so they will sink to the bottom of the reactor and mix with the bits of fuel that are there and won't wash out.

Neutron beams won't propagate through water. A foot of water is enough to completely scatter any neutrons.

Trying to cover it with concrete now is a big mistake. That would increase the danger and make it harder to deal with.

What they need are vacuum trucks to suck up debris and water and soil and filter the air though activated carbon with KI and clinoptilite. They need video surveillance from tethered balloons so they can see what is going on. They need hydraulic remote controlled stuff to move suction equipment into position.

They need to get the ambient radiation down so they can get in there and do stuff. They have a big site. They need to seal over the parking lot, put up concrete walls, pile non-radioactive stuff as shielding, put the radioactive debris in drums, then put the drums behind shielding.

That's one big motherfucking trip to Home Depot.

Need to know the number value of that Te129 and which Te129 is it. It has a half life of 33 days if it's 129mTe. If its the other Tellurium 129 then you might have proof as that has a half life of 60 minutes. Where are the lab results?

What if 100% of the nuclear stuff in Reactors 1,2 and 3 were dumped into the ocean? How would it disperse, over what time frame, what might be he consequences, etc.

10%? 20%?

Would it stick to the bottom of the ocean in places along the coast? Would it remain concentrated in certain habitats? I have a sense of what happens when radioactive stuff falls on a terrestrial surface, but not in the ocean. Anybody know?

(I'm asking for large amounts above because I'm not interested in "it disperses" as much as the part about when it does not disperse... I want to know if an argument could be made that a bad scenario is not so bad or no)

Greg, even Euglena can preferentially accumulate cesium-137 (e.g. http://www.jstor.org/pss/2833018). The seaweed will be suspect, as will predatory fish:

Cesium-137 is said to remain in the environment for a longer time than other substances as it takes roughly 30 years to lose half of its radioactive intensity. The Marine Ecology Research Institute says cesium-137 will not be directly absorbed into fish through gills but some species can accumulate the element by eating plankton and smaller fish. It's believed that through this process, the density of cesium in fish can increase 10 to 100 times the level in the seawater.


Plutonium can be accumlated by worms which can then be accumluated by things that eat the worms:

If you're asking about deposition patterns without respect to bioaccumulation, I can't help.


Yeah, I know about the food chain and trophic concentration and shit. I'm wondering about the mechanical and environmental nature of capture and dispersal.

Frankly, I'm wondering if dumping in the ocean is similar to, worse than, or better than, spreading over land. (And thus also wondering about the other combinations of things that could happen)

Greg: "I know about the food chain and trophic concentration and shit. I'm wondering about the mechanical and environmental nature of capture and dispersal.

Frankly, I'm wondering if dumping in the ocean is similar to, worse than, or better than, spreading over land. (And thus also wondering about the other combinations of things that could happen)"

Here's what I posted in a comment on the last thread. So far, I think it still captures the situation:

"The environmental disaster will be worsening for years. The reason, a few comments back, I posted the link to research on wetlands on the Irish coast (following an accident with substantial radiation release), is because the presence of radioactive materials was not only two orders of magnitude over legal limits-- 40 years after the fact-- weather conditions locally would stir up silt, and there can be periodic spikes in levels; the biologists were indicating the population declines of some birds seemed to be associated with this.

We can expect this along the east coast of Honshu, in the estuaries, and immediately offshore; nobody should be relying on dilution to cause a gradual decline. Because the release from Daiichi is continuing unabated, the total amount dispersed in the groundwater, soil, and sea is going to be on the order of tons."

What needs to be considered is how many cracks exist in the structures of the reactors, and in the ground around the plant (besides the one they simply couldn't ignore). There's no reason to assume there's just one, or that they all funnel to the ocean.

Considering this from Ana's feed:

"Three of the six reactors at the Fukushima Daiichi nuclear power plant experienced a jolt stronger than a worst case projection when hit by Japan's largest-ever earthquake March 11" (thanks for these, combining you and her, the best source of information on Daiichi)

If cracks radiate from the plant more or less randomly, some may be funneling radioactive materials inland. I happen to believe this is very likely.

I think these materials will not behave themselves in the way that would work best for us (neither collect in one neat package to be contained, nor disperse evenly and gradually so that exposure hazards are always equivalent to the 'average' exposure based upon the total amount released). We've seen the plume charts for the stuff directly sent into the air. That is how materials released into bodies of water also behave.

The currents seem likely to cause the materials to aggregate along the east coast of Honshu, where it will settle over time, some on the sea floor, some in marshlands and estuaries (tidal effects bring all sorts of crud back inland this way, pretty much whenever it's introduced close to shore).

Soil contamination from the materials heading down and inland from the reactors will, I think, continue to build and spread for a long time. Over many miles, and over many years. The assumption that fluids will settle and get trapped, even in bedrock, needs to be set aside. This is why I'm asking for folks to look at 'fracking' of shale to access gas, and how the fluids used to fracture the rock migrate into drinking water, and slowly wick into soil from below. Any disturbance of the soil (like plowing or using a bulldozer), once the materials have migrated upward, creates new exposure, and re-distributes the materials. I think we should consider that the rock beneath Daiichi was pretty severely fractured.

If I had to pick a metaphor to describe the process of these new exposures from disturbed soil, and new local 'hotspots' emerging as materials make their way to the surface, it would be the time-lapse maps of aftershocks, with each new one appearing, gradually filling the page. This would be in a random arc expanding from Daiichi, but in general moving further from the plant to the surrounding area over time.

Ripples of radiactive materials spreading from the plant, punctuated with bursts of localized concentration. I think this will happen over several hundred years, and I think there is no reversing the process at this point. The question that remains is how much of the 1700+ tons of fissile material is going to be released.

This quote from above pretty much nails it:

"Alexey Yablokov, member of the Russian academy of sciences, and adviser to President Gorbachev at the time of Chernobyl: "When you hear 'no immediate danger' [from nuclear radiation] then you should run away as far and as fast as you can."

By phillydoug (not verified) on 04 Apr 2011 #permalink

It looks like they may have decided to dump the water into the ocean to get rid of it so they can get in there and fix up the nuclear piles before they melt down or blow up (ad in H explosion) and spread it all around the farmlands and towns. Or at least, there are reports of this.

Greg: "It looks like they may have decided to dump the water into the ocean to get rid of it so they can get in there and fix up the nuclear piles before they melt down or blow up (ad in H explosion) and spread it all around the farmlands and towns. Or at least, there are reports of this."

With no guarantee that dumping the 'less radioactive' water buys them enough time to do that. So they might get the trifecta-- huge amounts flushed into the sea, plus meltdowns, plus explosions.

I'm suggesting that even with the most favorable scenario from right now-- they off-load enough water to permit cooling operations to continue, dismantle the cores and cooling ponds, and avert complete meltdowns (any that haven't already occurred) and more explosions-- there is still a massive amount of material already percolating in the soil, and the water already released will be affecting the coast for generations. That ship sailed March 14th, if not before.

(from http://www.timesunion.com/default/article/Nuclear-crisis-may-go-on-for-…

"The government said Sunday it will be several months before the radiation stops and permanent cooling systems are restored. Then there will be years of work ahead to clean up the area around the complex and figure out what to do with it.

Workers at the plant have often been forced to retreat from repair efforts because of high radiation levels.

On Sunday, plant operator Tokyo Electric Power Co. said it had found the bodies of two workers missing since the tsunami."

I guess it's a step in the right direction that the government is beginning to acknowledge the true scope of the problem.

The part about finding the bodies of the two workers underscores how dangerous the environment at the plant remains-- that's a fairly small, circumscribed area; they've had two people unaccounted for for three weeks, and only now have they located them. It again raises the question for me just how much water entered the plant grounds with the tsunami.

By phillydoug (not verified) on 04 Apr 2011 #permalink

I tried earlier with google to find some reliable source of info on what happens with radioactive substances in an ocean. I did not find much. Maybe I used wrong words to search, or maybe it's not in the internet or maybe it hasn't been studied that much.. Now it probably will be..

Anyway, our beautiful Baltic Sea being the most polluted and if I remember right, the most radioactive sea, there is quite a lot of info on this situation but it is significantly different from the Pacific because there is very little change of water.

I found this though:

And on the Baltic radioactivity, for example:

Nina, there may not be a lot of research, but we do know that dumping on radiactive materials into the ocean was banned in 1972, under "the London Convention-formally the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, 1972-which is a treaty under the International Maritime Organization (IMO)." (from:http://lawlibrary.unm.edu/nrj/35/3/09_moody_ogrady_nuclear.pdf)

The ban was instituted after a few decades of unregulated dumping had resulted in widespread contamination. What the above paper makes clear, we frankly don't know how much material has already entered the environment over the past fifty years.

We do have some examples of how the materials move through the environemnt. It's hard to make direct comparisons, but the processes seem to be fairly consistent-- concentrations of materials form near the release site, and move slowly though the soil and water. Natural weather conditions (and human activity) cause the material to disperse in locally greater quantities, something than happens periodically as long as the radioactive material remains.

An example from the Chelybinsk nuclear complex in the former Soviet Union illustrates the process:

(from The Bulletin of The Atomic Scientists, May 1991. http://books.google.com/books?id=tAwAAAAAMBAJ&pg=PA28&lpg=PA28&dq=dispe…)

"Resevoirs were created to keep water from flowing out of the most contaminated areas, and plant wastes were discharged into Karachay Lake, which has no outlet, instead of into the river.

The lake, actually a bog, eventually accumulated 120 curies of the long-lived radionuclides cesium 137 and strntium 90. In comparison, the Cernobyl accident released one million curies of cesium 137 and 220,000 curies of strontium 90.

In 1967 [about 15 years after dumping began], wind dispersed radiactivity from the lake, contaminating about 1,800 square kilomenters. Today, radioactivity has migrated about about two to three kilometers from the lake. A person standing on the shore near the area where the wastes are discharged from the plant would receive about 600 roentgens of ration, a lethal dose, in an hour."

And it is important not to get the feeling of being 'out of the woods' in the next few months:

(from: http://www.riverkeeper.org/campaigns/stop-polluters/indian-point/radioa…

"Each reactor routinely emits relatively low-dose amounts of airborne and liquid radioactivity. This radioactivity represents over 100 different isotopes only produced in reactors and atomic bombs, including Strontium-89, Strontium-90, Cesium-137, and Iodine-131. Humans ingest them either by inhalation, or through the food chain (after airborne radioactivity returns these chemicals to earth).

Each of these chemicals has a special biochemical action; iodine seeks out the thyroid gland, strontium clumps to the bone and teeth (like calcium), and cesium is distributed throughout the soft tissues. All are carcinogenic. Each decays at varying rates; for example, iodine-131 has a half-life of eight days, and remains in the body only a few weeks. Strontium-90 has a half-life of 28.7 years, and thus remains in bone and teeth for many years.

These chemicals are different from âbackgroundâ radiation found in nature in cosmic rays and the earthâs surface. Background radiation, while still harmful, contains no chemicals that specifically attack the thyroid gland, bones, or other organs.

â¦radioactive by-products continue giving off dangerous radioactive particles and rays for enormously long periods â described in terms of âhalf lives.â A radioactive material gives off hazardous radiation for at least ten half-lives. One of the radioactive isotopes of iodine (iodine-129) has a half-life of 16 million years; technetium-99 has a half-life of 211,000 years; and plutonium-239 has a half-life of 24,000 years. Xenon-135, a noble gas, decays into cesium-135, an isotope with a 2.3 million year half-life."

By phillydoug (not verified) on 04 Apr 2011 #permalink

correction: 120 curies (above) = 120 million curies

By phillydoug (not verified) on 04 Apr 2011 #permalink

South Korea has expressed concern to Japan over the release of radioactive water by Tokyo Electric Power Co. into the Pacific Ocean from the Fukushima Daiichi nuclear plant, Yonhap News Agency reported Tuesday, citing South Korean foreign ministry officials.


Shanghai is also concerned, I should think.


Someone has been graphing the radiation readings over here:

Unless South Korea provides a tanker to put the water in now there isn't much choice. So long as that water is on site they can't get at the critical systems and the longer they go without critical systems the worse it gets.

Is that deliberately dumped only little contaminated water really such a problem? Today they announced 7,5million times over legal limit of iodine and 1,1million times cesium in the seawater... :(


Yesterday it was told that Japan asked Russia to help to deal with radioactive waste. Yes, they have a loong experience in "dealing with" radioactive waste..


And they are "considering putting up underwater silt barriers at 3 locations, including one near a water intake for the No.2 reactor."


Through this site-- Theoretical Physics:(http://www.theoretical.com/2011/04/05/study-nuclear-fission-reactions-m…)

you get this link to a paper about the evidence for possible occurrences of fission (recriticality) since TEPCO attempted to shut down the reactors:


The key passage in the introduction (from my perspective):

"Most of the nuclear physicists and engineers with whom I have spoken since the incident cannot - will not - believe that it is possible that some of the fuel that is melting could somehow produce little pockets that could go critical."

If the belief is strong enough, evidence need not be considered. They *will not* believe it. I take it a step further, and say they will not imagine it; criticality should not happen in their world, and so it won't, hasn't and bears no further investigation.

And so concerns like this:

"Given these uncertainties it is nonetheless important for TEPCO to be aware of the possibility of transient criticalities when work is being done; otherwise workers would be in considerably greater danger than they already are when trying to working to contain the situation. A transient criticality could explain the observed 13 âneutron beamsâ reported by Kyodo news agency (see above). This analysis is not a definitive proof but it does mean that we cannot rule localized criticality out and the workers should take the necessary precautions."

need not be considered.

By phillydoug (not verified) on 05 Apr 2011 #permalink

Nina: âIs that deliberately dumped only little contaminated water really such a problem? Today they announced 7,5million times over legal limit of iodine and 1,1million timesâ cesium in the seawater... :( â

I share your concerns, and your questioning of official statements that such discharges represent âno immediate threatâ. The hazards are actually fairly well documented, if someone is inclined to attend to the historical record (nuclear advocates seem not to be so inclined).

On the one the one hand, we might say that what we have to go on is rough analogies of what may happen as a result of soil and water contamination. On the other hand, we might say instead that we actually have years of experience from around the world what happens when radioactive materials are introduced to the environment. They donât disperse and dilute the way nuclear advocates would want us to believe; the materials settle into the soil and silt and sand, they accumulate not far from the discharge point. And then they just don't go away. They sit for decades (really, they're going to sit for centuries), and then they get re-introduced to nearby communities by natural forces, or human activity:

(from http://www.fraw.org.uk/mei/archive/harwell-scram.pdf)

In our first report on safety at Harwell(1) we stated that pollution of the local groundwater from material dumped on the site was a strong possibility, because of the structure of the local geology. In 1990, solvents were discovered in the drinking water of people living around the Harwell area. The source of the water was a borehole three miles from the Harwell site. Later studies showed an underground plume of contamination extending out from the Harwell site towards this borehole.

During the early 1980's the British Geological Survey conducted extensive surveys of the Harwell area to determine whether or not the local strata were suitable to house a low-level waste disposal site. Their conclusion was that the local geology was very complex, very unpredictable, very porous, and very unsuitable for housing a waste repository. This, to any intelligent scientist, should have set alarm bells ringingâ¦

To solve the problem it is proposed that a special plants will be built above the waste sites. They will suck up the polluted groundwater, separate the solvents by blowing hot air through the water, and then filtering the air given off to remove the solvents. The groundwater pumped out will be run into the local sewer. Though a practical idea, the Liaison Committee Report does not mention two significant facts. Firstly, low-level radioactive waste is buried alongside the dump sites, and this process will mobilise as much radioactive material as it will chemical contaminants. Secondly, more than 3000 gallons of water per day will be abstracted from beneath the Harwell site. The local water table is already low through abstraction for drinking water. Extra abstraction could have significant effects on the local environment and agriculture.

Downstream AWE Aldermaston has its pipeline, and AWE Burghfield also discharges effluent into the Thames via the River Kennet. What are the cumulative effects of these three discharge points?. It has been noted that an enhanced level of beta activity exist in the silt near the Harwell outfall into the Thames, and that these levels follow a pattern with the levels of caesium and plutonium isotopes within the silt."

(from: http://www.cdphe.state.co.us/rf/contamin.htm)

Contaminants were released into the air and water during routine manufacturing at the Rocky Flats Plant located 16 miles northwest of downtown Denver, as well as during unplanned incidents. The Historical Public Exposures Studies on Rocky Flats were conducted to identify potential health risks to residents in nearby communities who may have been exposed to chemical and radioactive releases from Rocky Flats during its years of operation (1952 to 1989). After extensive study, researchers determined that nearby communities received the greatest exposure to contaminants through the air, rather than from drinking water.

When the holding ponds on Walnut Creek were drained and reconstructed in 1972-73, some of the pond water and sediments flowed downstream to Great Western Reservoir. Levels of radioactivity in water from Walnut Creek at Indiana Street (the plant's eastern boundary) increased almost eighty-fold during the peak rebuilding phase. By June 1973, the radioactivity levels had returned to pre-pond reconstruction levels.

In the past, the highest levels of plutonium were detected in water that went into the south branch of Walnut Creek. An estimated one gram of plutonium may have been released to South Walnut Creek from the plant's start-up in 1952 through 1969. Much of the plutonium in liquid wastes settled to the bottom of the holding ponds and eventually in the sediments at the bottom of Great Western Reservoir.

The greatest amounts of tritium were released to surface water in April 1973, when wastewater containing tritium flowed into Walnut Creek leading to Great Western Reservoir. The highest tritium concentrations measured in the reservoir during this time were from two to 20 times higher than normal.

The discharge of plutonium into Walnut Creek and Woman Creek over many years has resulted in the accumulation of contamination in the sediments at the bottoms of Great Western Reservoir and Standley Lake. Core samples taken of the sediments show low but measurable concentrations of contamination from 5-10 inches deep in the sediments."

By phillydoug (not verified) on 05 Apr 2011 #permalink

The fuel was near the end of its life, so it has ~1% fissile material, either U235 or Pu239. B10 has a cross section for neutron absorption ~5x that of U235 or Pu239. B10 is ~20% of natural boron. If you have more than one atom of B10 per 5 atoms of fissile material, the B10 will absorb more neutrons than the fissile material and you can't reach criticality. U235 and Pu239 both produce less than 2 neutrons per thermal neutron absorbed. If one of those neutrons is absorbed by B10, a chain reaction can't happen.

So to prevent criticality you need ~ one atom of natural boron per atom of fissile material. If there are 100 tons of uranium at 1% fissile material, you have ~ 1000 kg of fissile material, or about 1000/235 kg/mole = 4.25 kg-mole. So you need 4.25 * 11 kg/mole = 46 kg natural boron to completely prevent criticality in the 100 tons of fuel.

That is not a lot of boron. Reports have been that TEPCO has been putting tons and tons of boron in the water they are using to cool the fuel. If even a fraction of that boron is staying in the reactor, it will prevent criticality.

The report on âneutron beamsâ does not seem credible to me.

A radiation monitor at the troubled Fukushima Daiichi nuclear power plant says workers there are exposed to immeasurable levels of radiation.

The monitor told NHK that no one can enter the plant's No. 1 through 3 reactor buildings because radiation levels are so high that monitoring devices have been rendered useless. He said even levels outside the buildings exceed 100 millisieverts in some places.

Pools and streams of water contaminated by high-level radiation are being found throughout the facility.

The monitor said he takes measurements as soon as he finds water, because he can't determine whether it's contaminated just by looking at it. He said he's very worried about the safety of workers there.

Contaminated water and efforts to remove it have been hampering much-needed work to cool the reactors.

The monitor expressed frustration, likening the situation to looking up a mountain that one has to climb, without having taken a step up.

Tuesday, April 05, 2011 19:51 +0900 (JST)