Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[wasteinc]

Borek you are right about how everyone twists everything in order to get his/her point of view. You are also right that that kind of models are at best inaccurate.

but in your second paragraph you don't use what you preach. Demographic statistics in Ukraine are a mess because after 1991, a big chunk of the population left the country. It was estimated that around 1998-2000 nearly 40% of th reproducing capable popolution wasnt living in Ukraine.
Also many of the liquidators came from other parts of USSR that became different states, confusing data even more.
Also the transition from USSR to liberal economies has decreased the life expectancy more than 10 years, in only 10 years. The Chernobyl disaster can mask itself in the economic one.

And to add insult to injury, we have no big epidemiological studies about Chernobyl. It seems that no-one really want to know.

Also the UN report about the chernobyl vastly underestimates everything to a point of becoming upsurd.

and when we are talking about the lives of so many million people the agnostic attitude that most of the industrialized world usually takes is not appropriate.

That also goes to the toxicity of chemical substances, not only radiation exposure. The mantra is that if it is not proven to hurt, it means it can be used. An attitude so much propagated by the tabaco industry.

So the agnostic position "if dose X , is not proven to be hurtful, then we can apply it to everyone reassuring that there is no danger, is quite biased by itself"

sorry if I got carried away, my respects to you and all the other people writing here

 

[NUCENG]

Surely too my lives are at stake to take that attitude. This form of modelling is the best means available for estimating radiation risk.

Reading Busby's report, he notes that the ICRP model was developed based on the effects on long-term survivors of Hiroshima and Hagasaki.

"This method cannot apply to internal doses from radioactive substances, called radionuclides, which have been inhaled or ingested in food or water. ... The ICRP method annot either be applied to inhaled or ingested hot particles, which are solid but microscopic and can lodge in tissue delivering high doses to local cells. There is a great deal of evidence that exposure to internal radionuclides is up to 1000 times more harmful than the ICRP model concludes."

"This method [the ECRR model] was applied to the results of the study of Tondel et al 2004 in Sweden who found 11% increase for 100kBqm-2 surface contamination. It almost exactly
predicted what these researchers found. These researchers carried out regressions to correlate cancer increases with area contamination by Cs-137 and other radionuclides from Chernobyl. The error factor relating the ICRP risk model, which employs external radiation, was upwards of 600-fold."

So the ICPR method drastically underestimated cancer rates from Chernobyl because it neglects the effects of inhaled or ingested radionuclides & hot particles.

Based on a quick read the new method used is taking MEXT measurement data that only goes back to about 10 days after the accident to estimate total effective dose to the population. The readings of contamination may not be adjusted for background radiation. If so the calculated result of a 66% increase in cancer over 50 years would be grossly overstated. Further, if it doesn't account for evacuations that have been performed or may occur within the assumed 1 year exposure period, it would again be overstating the problem.

The latest IAEA updates on Chernobyl that I have read are still unable to demonstrate statistically an increase in latent cancers other than the thyroid cancers and acute dose cases early in the event. If you have later information I'll add it to the list of other new reports I have found while following this thread.

I would characterize this report as a first guesstimate of the worst case. It is the starting point not the final answer.

Please excuse occasional cases of gallows humor. I am pretty sure no one here is making light of the potential consequences of this accident. But it is small compared to the consequences of the earthquake/tsunami.

 

[|Fred]

now back to the pant...
the latest paper 'schematic' from tepco about the trench leak (translated)

ps: http://www.meti.go.jp/press/2011/04/20110402003/20110402003-3.pdf
The temp of the unit 2 pool has been rising all week and now is at 72°.. might become an issue if we can't cool this one or inject water

 

[AntonL]

now back to the pant...
the latest paper 'schematic' from tepco about the trench leak (translated)

The leak must be quiet severe, No sea water analysis available for since 31 March, high levels seemingly are not being published.

550 to 600 m3 or tonnes of water per day are being used "Feed and Bleed" cool the reactors, part of this volume escapes as steam the rest being accumulated in basement, trenches and escaping into the subsoil and sea. This process will continue for weeks and months, it will only stop once secondary cooling can be established and cooling water circulated in a closed system to the reactor.

The pumps to do this circulation all have now been submerged with extreme high radiation water for nearly a week, even if basements are pumped dry it will take time to decontaminate.

Will the solution be in constructing new secondary cooling systems? this will take months.

 

[ZZR Puig]

For those concerned or just curious, it would be worth to have also another perspective about radiation health effects from the hand of one of the best experts in the field, having been chairman of UNSCEAR studying the Chernobyl accident consequences.
http://www.21stcenturysciencetech.com/Articles_2010/Summer_2010/Observations_Chernobyl.pdf" )

In case you find that paper too long, you may as well get the general idea from a briefer and a somewhat less recent article:
http://www.21stcenturysciencetech.com/articles/chernobyl.html"

 

[timeasterday]

Looks like core pressure and temperature on #1 are creeping back up. Also noticed a new measurement for radiation.

http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/v8/plot-un1-full.png

 

[TCups]

Lies, damned lies and statistics?

A day without radiation is like a day without sunshine.

Linear interpolation from high dose exposures, primarily from clock workers who painted the glowing green hands on clocks, survivors of the atomic bombings of Japan, and now, data accumulating from Chernobyl shape the assumption that there is no safe, low dose of radiation. The notion that no safe low dose of radiation exists is, of course, absurd, or as I like to say, "A day without radiation is like a day without sunshine." Also, it is well known that the human body has biological mechanisms for effective repair of sublethal radiation exposure. Repeated small, divided doses over time are not equal to the sum of all of the divided small doses given in a single exposure. For ionizing radiation, reverse DNA transcriptase plays an important role in cell repair. BTW, caffein is one of the most potent inhibitors of the activity of reverse DNA transcriptase. Think I will have a cup now.

Google "BEIR Report" (Biological Effects of Ionizing Radiation).
http://www.e-radiography.net/radsafety/rad_biology.htm

Just for fun, Google: The Mega Mouse Project and read what researchers found about a study of two populations of about 7,000,000 lab mice, one exposed to intermittent low doses of radiation and another exposed to no radiation over a period of several years. One population had a significantly better outcome than the other as I recall.

 

[TCups]

There is one thing in the footage of the reactor 3 explosion that I have not seen mentioned. There seems to be a huge recoil component going horizontally northbound. Look at this video, seconds 16 to 30. Apart of the vertical ballistic effect there is a cloud of dust/vapor moving very quickly and very far to the left. By 26'' we cannot even see the leftmost antenna, then the antenna reappears but in the base of it we still see dust moving northbound. Any explanations?

As I am won't to do from time to time, here is a song lyric reply:
"The rain is Tess, the fire is Joe, and they call the wind Mariah."

By the way, this photo is taken from the south-southwest of the explosion and Marian (aka wind) is blowing to the west.

BTW, as someone has very correctly pointed out, they are not antennas -- they are towers for venting the reactor buildings.

 

[timeasterday]

I ran into a video clip from a camera mounted to the boom of a crane used to pump water into the SFP of reactor building 4.

http://www.ustream.tv/recorded/13684184

Is there a dead worker in a white protection suit along the bottom middle of the shot in the beginning? That was very unsettling when I saw that.

 

[TCups]

The leak must be quiet severe, No sea water analysis available for since 31 March, high levels seemingly are not being published.

550 to 600 m3 or tonnes of water per day are being used "Feed and Bleed" cool the reactors, part of this volume escapes as steam the rest being accumulated in basement, trenches and escaping into the subsoil and sea. This process will continue for weeks and months, it will only stop once secondary cooling can be established and cooling water circulated in a closed system to the reactor.

The pumps to do this circulation all have now been submerged with extreme high radiation water for nearly a week, even if basements are pumped dry it will take time to decontaminate.

Will the solution be in constructing new secondary cooling systems? this will take months.

LAKE FUKUSHIMA?

So it would seem that the alternative to the "ocean dilution solution" would be even worse. And even if they did contain those sorts of volumes of contaminated water being pumped for isolation and long term storage, it would be many many years before Lake Fukushima could be used for any recreational purposes, right?

 

[AntonL]

Looks like core pressure and temperature on #1 are creeping back up. Also noticed a new measurement for radiation.

http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/v8/plot-un1-full.png

Relate temperature graphs to "Feed and Bleed" cooling rate
116 --> 133 l/min on 29 March 08:32
133 --> 117 l/min on 1 April 16:18

todays temperature readings (2 April)
04:00 261 degree C
12:00 259 degree C

A delicate balancing act between reactor temperature and and cooling in-feed and contaminated out-bleed of water and steam.

 

[etudiant]

NHK reports iodine 131 concentration in sea water 40 km from the plant is 79 bequerels/liter,
twice the Japan standard for water emissions from nuclear sites.
Unless there is a current that carries the water from the plant fairly unmixed, this is a very large amount of iodine 131.
TEPCO said the air reading above the trench from which water was leaking was above 1000milliSeverts/hr.
So the outflow has to be near glowing.
Are the damaged fuel elements just getting rinsed into the ocean?

 

[AntonL]

NHK reports iodine 131 concentration in sea water 40 km from the plant is 79 bequerels/liter,
twice the Japan standard for water emissions from nuclear sites.
Unless there is a current that carries the water from the plant fairly unmixed, this is a very large amount of iodine 131.
TEPCO said the air reading above the trench from which water was leaking was above 1000milliSeverts/hr.
So the outflow has to be near glowing.
Are the damaged fuel elements just getting rinsed into the ocean?

Attached are the basement water sample analysis of 26 March (forget the I-134 that was proven wrong) - the I-131 dilution of the sea sample is 146 million compared to basement 2 water (beware of different units /cm³ and /litre)

Yes - your last statement is correct!
Also the sub-terrain water is equally badly polluted

Apparently Tepco have found the leak, a 20cm long crack that leaks 500m³/day ...

 

[michael200]

this is in reply to post 2368:

Ok. first: Mr Gunderson has no other interest than in spreading panic. Railing in the third image down is the handrail for the Rx building overhead crane. what Gunderson is contemplating as fuel racks ejected from the spent fuel pool is probably in reality pool storage locations for radioactive "junk" (old used up neutron monitors) previously removed from the reactor vessel. sorry, but I'm still missing this theory of H2 fire in the unit 4 spent fuel pool. Look at the pictures of the reactor building for Unit 4. There is significant fire damage and blown out walls well below the level of the refuel floor. If significant H2 was generated in the fuel pools, then how did it magically become heavier than air and propagate to the lower levels of the Rx building? Agree that it would be beneficial to see some pictures of the U4 building on 15March when a fire was reported to start, stop and then start again.

 

[michael200]

Unit 4 was in a maintenance outage. the green crane to the right was probably a maintenance crane for doing work for equipment in the dryer/separator pool. When a BWR enters an outage, the Rx vessel needs to be disassembled to get access to the Rx fuel. firs the drywell head is removed (thats that big orange dome structure you see in the U4 pictures), then the Rx vessel head insulation, then the Rx vessel head is removed. The drywell head, Rx head insulation and Rx vessel head are stored on the refuel floor.
Next the Rx steam dryer and then the Rx steam separator are removed from the Rx pressure vessel. These items are large and have some level of contamination so they are stored in a large swimming pool/pit.

 

[etudiant]

Attached are the basement water sample analysis of 26 March (forget the I-134 that was proven wrong) - the I-131 dilution of the sea sample is 146 million compared to basement 2 water (beware of different units /cm³ and /litre)

Yes - your last statement is correct!
Also the sub-terrain water is equally badly polluted

Apparently Tepco have found the leak, a 20cm long crack that leaks 500m³/day ...

500 m**3/day is about 500 tons, about double the daily water used for reactor cooling at the 150 liter/min rate indicated by the NISA. Suggests this leak is drawing on more than just reactor 2.

Does anyone have any idea of how a thin slurry of irradiated reactor fuel could be stored?
Maybe freeze it in place and wait a few years for decay?

 

[TCups]

The movement of the cloud to the right is almost as far at this time - although the wind is behind it.

The exhaust stack seems to disappear briefly as the shaddow from the large vertical cloud blocks direct sunlight. This is a low contrast video, shot from many km away. Note there is almost no difference in tone between the shaded sides of the builkdings and the background sky.

OK, my bad. I misunderstood.

The propagation of the smoke to the right (toward the northeast) at first glance looked discontinuous. I wondered if there were additional ground impacts kicking up dust and smoke. But just as the shadow from the vertical blast transiently obscures the visibility of the tower between units 1 and 2, it also transiently obscures the apparent continuous propagation of the smoke along the ground.

The ground smoke and dust is likely kicked up, at least in part, by a horizontally propagating shock wave, which would not be, in effect, bucking the wind. The shock wave then kicks up dust and debris on the ground.

Another explanation might be that the southeasterly winds create air currents that, at higher altitudes, cary dust and smoke in a southeasterly direction, toward the sea. But the prevailing winds are blowing from over the high-banked berm and high ground, back to the west side of the buildings, so at ground level, a swirling eddy current of air flow might well be blowing in a different direction as well.

Finally, I would not dismiss the possibility that additional debris blasted outward struck the ground and kicked up more dust that way as well.

 

[Joe Neubarth]

How come we are all still alive?

Resistance to some background radiation is built into our biochemistry, we evolved this way as the radiation was always with us. It is dose that makes a poison. I often have a feeling that one of the most important reasons why general public is so afraid of the nuclear energy lies in the fact they were told what you wrote above. Radiation is a not a thing to be treated lightly, but there is no doubt there are levels that are safe. Or at least - their health effect is unmeasurable.

Borek, I am going to disagree with you on this. I am convinced that any radiation in excess of normal background exposure is not good for you and can kill you. It only takes one gamma ray to damage a DNA string in a cell in your skin, lungs, marrow or whatever to start a cancer cell growing.

The first gamma ray to hit you can trigger cancer growth or the Tenth-Trillion one can. Mathematically we have the same chance no matter which gamma ray it is. I have four skin cancers that are more than likely related to solar radiation, but could be from gamma or Beta radiation from my reactor plant operating days. There is no way of knowing which strike of radiation caused the DNA damage that created the cancers. I also have three tumors growing in my body (Well, one might be dying as the surgeons blocked off the arteries feeding the tumor.). That one was on my Kidney, the other two are on my adrenal gland and my diaphragm area. According to the doctors all are benign. One of the skin cancers is aggressive and was removed yesterday amidst a lot of blood. Those suckers grow roots in multiple directions.

Knowing what I know now, I would have stayed away from nuclear power in my youth. I am 63 now and was last in an operating plant in 1973. Nearly forty years from my last exposure to radiation that was not necessary in normal life. I advise anybody and everybody if you do not need the radiation exposure to survive, stay away from it.

The moral to the story is to avoid any extra exposure to radiation if you can. The life you save may be your own.

 

[Astronuc]

500 m**3/day is about 500 tons, about double the daily water used for reactor cooling at the 150 liter/min rate indicated by the NISA. Suggests this leak is drawing on more than just reactor 2.

Does anyone have any idea of how a thin slurry of irradiated reactor fuel could be stored?
Maybe freeze it in place and wait a few years for decay?

I doubt that anyone would want to store a slurry or solution of fission products or fuel.

I would recommend that it be chemically processed in much the same way normal fuel is fabricated. Basically, one simply precipitates the solution. The precipitate is dried, then calcined and finally vitrified, possibly with a glass additive. The solid can then be stored permanently in a geological repository.

One possibility would be to recover the fuel, or fissile and fertile material.

 

[Joe Neubarth]

An old saying:
The only statistics you can believe are those you complied yourself

BUT, even then I do not always trust them.

 

[TCups]

Unit 4 was in a maintenance outage. the green crane to the right was probably a maintenance crane for doing work for equipment in the dryer/separator pool. When a BWR enters an outage, the Rx vessel needs to be disassembled to get access to the Rx fuel. firs the drywell head is removed (thats that big orange dome structure you see in the U4 pictures), then the Rx vessel head insulation, then the Rx vessel head is removed. The drywell head, Rx head insulation and Rx vessel head are stored on the refuel floor.
Next the Rx steam dryer and then the Rx steam separator are removed from the Rx pressure vessel. These items are large and have some level of contamination so they are stored in a large swimming pool/pit.

@michael20

The damage to the lower levels of both Bldg 3 and 4 have been puzzling. I think I know how hydrogen got into the lower levels of Bldg 3, but I am darned if I can figure out a mechanism for the apparent blast in the lower levels of Bldg 4 resulting from hydrogen formed in the SFP4.

I did just read one interpretation that "hot" spent fuel rods were in the accessory SFP4 (what is the proper name?) and that the smaller pool adjacent to the larger SFP4 was damaged, breeched, and dumped glowing hot fuel rods, accounting for reports of recurring fires in Bldg 4.

 

[TCups]

Even the strength of the blast at Unit 3 did not blow out every single wall panel of the floor below the top (reactor access) floor. And the top floor (the top two tiers of columns) is where hydrogen was most likely to accumulate. Not only did the explosion at unit 4 take out every panel on the east and west side of the building of the floor below the reactor access floor (ie, at the same level as the SFP), it also appears to have taken out one south side panel a floor below the SFP (ie, two floors below the reactor access floor) and also, it did much less damage to the roof beam superstructure than did the blast at Unit 3, and it left the north wall of the top floor partially collapsed inward, and it left at least two panels on the east and west sides of the top floor intact. Compare, carefully, the east, west, and south elevation views.

http://nimg.sulekha.com/business/original700/aerial-2011-3-30-1-11-12.jpg

http://nimg.sulekha.com/business/original700/aerial-2011-3-30-0-20-7.jpg

http://nimg.sulekha.com/business/original700/japan-earthquake-2011-3-30-0-50-12.jpg

I think I can explain the damages at Bldg 3, but Bldg 4's explosion still has me baffled. Above quote from post #2012

 

[TCups]

SUBLETHAL REPAIR OF CHROMOSOME DAMAGE FROM IONIZING RADIATION FOR DUMMYS


(corrections welcome - it's been a long time since I studied it)

Borek, I am going to disagree with you on this. I am convinced that any radiation in excess of normal background exposure is not good for you and can kill you. It only takes one gamma ray to damage a DNA string in a cell in your skin, lungs, marrow or whatever to start a cancer cell growing.

The moral to the story is to avoid any extra exposure to radiation if you can. The life you save may be your own.

Joe:

http://en.wikipedia.org/wiki/DNA_repair

Very simplistic explanation: Biochemically, DNA is a two-stranded mega-molecule. Ionizing radiation does chromosome damage by the ionization leading to free radicle formation (O-1, or oxygen free radicles as I recall) which leads to a break in one side of the DNA strand. In brief, at relatively low exposure rates, and even moderate exposure rates of ionizing radiation, it is far more likely that these ionization events result in damage to only one side of the DNA chain. Only if there is enough radiation exposure to cause a "double hit" and a double chain break in the DNA strand, is irreversible damage done to a DNA strand and thus, irreparable chromosomal damage.

Biochemically, there are single strand breaks going on all the time from a number of causes, but the body has a very efficient way of repairing these. Reverse DNA transcriptase attaches to one side of the DNA strand and, in effect by reading one side of the chain, repairs the break in the other side, like a zipper. But if this reparative enzyme encounters a break in both strands simultaneously (both sides of the zipper are broken) it can't make the repair.

But double chain breaks are uncommon except in very high, single exposures to ionizing radiation (alpha, beta, x-ray, gamma), with one exception: alpha particles. This is because of the high mass and double charge of the alpha particle (2P+2N)++ vs beta (1e)- vs x-ray and gamma (photons, no charge). But alphas don't penetrate from external exposure. On the other hand, if you ingest an alpha emitter, you are probably screwed (can I say screwed on this forum?)

At exposure rates sufficient to have a high enough number of ionizing gammas to statistically cause a high number of double chain breaks, then, yes, permanent damage is done. At lower exposures, and probably even moderately high exposures, it is probably business as usual for the DNA machinery of living organisms.

Take a big dose of Vitamins E and C (anti-oxidizing agents, fat and water soluble respectively) if you are worried about low level radiation exposure, and relax. Again, look up the Mega Mouse Project for some interesting reading.

It theoretically might only take one alpha "hit" on a critical part of a cancer forming or cancer preventing chromosome (read up on oncogenes, proto-oncogenes, etc. in your spare time) to start a cancer, perhaps, but the probability of a single ionizing event from any other source of radiation causing a cancer is non-existent, IMO.

 

[AntonL]

... I am convinced that any radiation in excess of normal background exposure is not good for you and can kill you. It only takes one gamma ray to damage a DNA string in a cell in your skin, lungs, marrow or whatever to start a cancer cell growing. ...

What is normal background radiation - do we have references on background radiation before 16 July 1945. All I know is that steel from warships sunk before 1945 is being salvaged to line and shield laboratories for sensitive low level radiation measurements. Steel produced today has a higher background radiation due to diluted atomic radiation entrapped into it during the manufacturing process, this we now simply define as normal background.

Radioactivity in the atmosphere has increased over time with the continual testing of atomic bombs of all types. Steel makers need vast amounts of air to make steel so it would follow that steel made nowadays contains certain amounts of radioactivity. Prior to dropping the first A bomb in 1945, steel was radioactive free, and the only source of this 'clean' steel left lies in pre 1945 wrecks that lie on the seabed.

A bit off topic
http://www.youtube.com/watch?v=jfpQNfcRE1o&feature=player_embedded
of the 2053 suns there have been 711 in the atmosphere or underwater: 215 by the U.S., 207 by the Soviet Union, 21 by Britain, 45 by France and, 23 by China. Approximately 3,830 kilograms of plutonium has been left in the ground as a result of all underground nuclear testing and some 4,200 kilograms of plutonium has been discharged into the atmosphere as a result of atmospheric nuclear testing.

 

[hoyrylollaaja]

I think I can explain the damages at Bldg 3, but Bldg 4's explosion still has me baffled. Above quote from post #2012

Could it be, that since it was undergoing scheduled stoppage, some doors and hatches were open that in normal running condition would be closed and sealed?

 

[SoSanl]

Hi all, thanks to all for there effort they put into this topic.

found link not sure if this new vid of interior has been post before or not.

http://www.telegraph.co.uk/news/worldnews/asia/japan/japan-earthquake-and-tsunami-in/8420814/Video-of-smashed-interior-at-Fukushima-nuclear-plant.html

or same vid (first link is better u see more):
New Video Shows Smashed Interior of Fukushima Nuclear Reactor

 

[|Fred]

Hi. yes it has, over four time I think: it's building n°4 on the south wall looking at the fuel pull with a wide lens giving a nonnatural perspective

 

[etudiant]

I doubt that anyone would want to store a slurry or solution of fission products or fuel.

I would recommend that it be chemically processed in much the same way normal fuel is fabricated. Basically, one simply precipitates the solution. The precipitate is dried, then calcined and finally vitrified, possibly with a glass additive. The solid can then be stored permanently in a geological repository.

One possibility would be to recover the fuel, or fissile and fertile material.

Well, the question was for the crack effluent, 500m**3/day and super radioactive.
It seems that precipitating anything out of such a volume would be a large task, but it might be hazardous even to filter it.
Maybe buy up some old supertankers and use them for storage.
Tow them somewhere where tropical storms are rare and then work hard to find a way to deal with them.
The more stuff can be put on hold for a while the better, at least for this situation.

In that context, any thoughts on moving out the spent fuel from the undamaged reactors and the common pool, just in case things here get seriously messy and people have to leave?

 

[TCups]

Could it be, that since it was undergoing scheduled stoppage, some doors and hatches were open that in normal running condition would be closed and sealed?

That has been suggested. Even so, to transmit the blast force downward with sufficient force to blow almost all of the walls one level below the top of the SFP4, and several wall panels two levels below, and yet leave most of the superstructure of the roof girders intact, and even have the north wall of the top floor collapse inward speaks to me of a very different kind of explosion, doors opened or closed. A lot of the damage is isolated around the northeast corner of Bldg 4.

I can maybe get to that kind of damage if hot fuel drops through the bottom of one or the other pools in the top floors and causes and additional lower level blast that spreads outward around the reinforced inner walls of the primary containment. But I just can't wrap my arms around the open door theory.

 

[KateB]

SUBLETHAL REPAIR OF CHROMOSOME DAMAGE FROM IONIZING RADIATION FOR DUMMYS


(corrections welcome - it's been a long time since I studied it)
Joe:

http://en.wikipedia.org/wiki/DNA_repair

Very simplistic explanation: Biochemically, DNA is a two-stranded mega-molecule. Ionizing radiation does chromosome damage by the ionization leading to free radicle formation (O-1, or oxygen free radicles as I recall) which leads to a break in one side of the DNA strand. In brief, at relatively low exposure rates, and even moderate exposure rates of ionizing radiation, it is far more likely that these ionization events result in damage to only one side of the DNA chain. Only if there is enough radiation exposure to cause a "double hit" and a double chain break in the DNA strand, is irreversible damage done to a DNA strand and thus, irreparable chromosomal damage.

Biochemically, there are single strand breaks going on all the time from a number of causes, but the body has a very efficient way of repairing these. Reverse DNA transcriptase attaches to one side of the DNA strand and, in effect by reading one side of the chain, repairs the break in the other side, like a zipper. But if this reparative enzyme encounters a break in both strands simultaneously (both sides of the zipper are broken) it can't make the repair.

But double chain breaks are uncommon except in very high, single exposures to ionizing radiation (alpha, beta, x-ray, gamma), with one exception: alpha particles. This is because of the high mass and double charge of the alpha particle (2P+2N)++ vs beta (1e)- vs x-ray and gamma (photons, no charge). But alphas don't penetrate from external exposure. On the other hand, if you ingest an alpha emitter, you are probably screwed (can I say screwed on this forum?)

At exposure rates sufficient to have a high enough number of ionizing gammas to statistically cause a high number of double chain breaks, then, yes, permanent damage is done. At lower exposures, and probably even moderately high exposures, it is probably business as usual for the DNA machinery of living organisms.

Take a big dose of Vitamins E and C (anti-oxidizing agents, fat and water soluble respectively) if you are worried about low level radiation exposure, and relax. Again, look up the Mega Mouse Project for some interesting reading.

It theoretically might only take one alpha "hit" on a critical part of a cancer forming or cancer preventing chromosome (read up on oncogenes, proto-oncogenes, etc. in your spare time) to start a cancer, perhaps, but the probability of a single ionizing event from any other source of radiation causing a cancer is non-existent, IMO.

Sorry, as this is my forte, I have to interject here. Double strand breaks ARE repairable. It is more complex, requires more energy, and correct conditions (terrain) but it can be done. Generally by non-homologous end joining. Also free radicals are not always oxygen; they say free radicals 'oxidize' if they go through a redox reaction. It is called "oxidation" because oxygen is one of the most reactive and efficient at this (and probably the first element to be studied involving these reactions). ROS contain oxygen, but "free radicals" as a general term, do not have to. Free radicals are pretty much any ion that causes a redox reaction outside of the homeostatic redox reactions for normal body processes. But, our bodies use ions or "radicals" daily for redox signaling, repairing DNA, etc. Basically, it all depends on the terrain, as to whether your body develops cancer as a result of exposure to ionizing radiation (i.e. how much of those antioxidants are available for your body to neutralize the the FR or ROS). Of course, there are instances where the body has been over-assaulted where it cannot make up the difference of repair to damage, and in that case cell death is the result. (Edit: there are also cases where DNA repair is incorrect, the mitotic check points are compromised, and cancer can develop as a result)
Hope that helps!

 

[TCups]

Unit 4 was in a maintenance outage. the green crane to the right was probably a maintenance crane for doing work for equipment in the dryer/separator pool. When a BWR enters an outage, the Rx vessel needs to be disassembled to get access to the Rx fuel. firs the drywell head is removed (thats that big orange dome structure you see in the U4 pictures), then the Rx vessel head insulation, then the Rx vessel head is removed. The drywell head, Rx head insulation and Rx vessel head are stored on the refuel floor.
Next the Rx steam dryer and then the Rx steam separator are removed from the Rx pressure vessel. These items are large and have some level of contamination so they are stored in a large swimming pool/pit.

There was a good picture of that posted earlier -- the same shot showing the open fuel transfer chute and the fuel handling machine.

 

[Joe Neubarth]

SUBLETHAL REPAIR OF CHROMOSOME DAMAGE FROM IONIZING RADIATION FOR DUMMYS


(corrections welcome - it's been a long time since I studied it)



Joe:

http://en.wikipedia.org/wiki/DNA_repair

Very simplistic explanation: Biochemically, DNA is a two-stranded mega-molecule. Ionizing radiation does chromosome damage by the ionization leading to free radicle formation (O-1, or oxygen free radicles as I recall) which leads to a break in one side of the DNA strand. In brief, at relatively low exposure rates, and even moderate exposure rates of ionizing radiation, it is far more likely that these ionization events result in damage to only one side of the DNA chain. Only if there is enough radiation exposure to cause a "double hit" and a double chain break in the DNA strand, is irreversible damage done to a DNA strand and thus, irreparable chromosomal damage.

Biochemically, there are single strand breaks going on all the time from a number of causes, but the body has a very efficient way of repairing these. Reverse DNA transcriptase attaches to one side of the DNA strand and, in effect by reading one side of the chain, repairs the break in the other side, like a zipper. But if this reparative enzyme encounters a break in both strands simultaneously (both sides of the zipper are broken) it can't make the repair.

But double chain breaks are uncommon except in very high, single exposures to ionizing radiation (alpha, beta, x-ray, gamma), with one exception: alpha particles. This is because of the high mass and double charge of the alpha particle (2P+2N)++ vs beta (1e)- vs x-ray and gamma (photons, no charge). But alphas don't penetrate from external exposure. On the other hand, if you ingest an alpha emitter, you are probably screwed (can I say screwed on this forum?)

At exposure rates sufficient to have a high enough number of ionizing gammas to statistically cause a high number of double chain breaks, then, yes, permanent damage is done. At lower exposures, and probably even moderately high exposures, it is probably business as usual for the DNA machinery of living organisms.

Take a big dose of Vitamins E and C (anti-oxidizing agents, fat and water soluble respectively) if you are worried about low level radiation exposure, and relax. Again, look up the Mega Mouse Project for some interesting reading.

It theoretically might only take one alpha "hit" on a critical part of a cancer forming or cancer preventing chromosome (read up on oncogenes, proto-oncogenes, etc. in your spare time) to start a cancer, perhaps, but the probability of a single ionizing event from any other source of radiation causing a cancer is non-existent, IMO.

Your comment is appreciated and educational. The fact remains that ONE piece of radiation is all it takes to start a cancer growing and cancer kills millions annually. Yes, both strand sides of DNA have to be damaged for a permanent change to occur, but that can happen from one ray. Though it is most likely that it would take two rays to damage the DNA stand about the same time, it is still one ray that does the final damage. If it is the second one, so be it. If you never were exposed to it you would not have the cancer. Such is life, and death.

 

[|Fred]

The Tepco press point that just finished talk about the picture of unit 4 .. I did not understand much (understatement) , they seems to pay attention to the pipes bellow though.

The missing data.,so far we did not have much data related to the reactor before the 12th evening now we have a bit more

[PLAIN]http://k.min.us/imHJgS.jpg

 

[KateB]

Your comment is appreciated and educational. The fact remains that ONE piece of radiation is all it takes to start a cancer growing and cancer kills millions annually. Yes, both strand sides of DNA have to be damaged for a permanent change to occur, but that can happen from one ray. Though it is most likely that it would take two rays to damage the DNA stand about the same time, it is still one ray that does the final damage. If it is the second one, so be it. If you never were exposed to it you would not have the cancer. Such is life, and death.

You can develop cancer if only one side is compromised. In transcription, only one side of the DNA is used, called the template strand. If this strand has one or more base pair substitutions/deletions/etc., it could code for the wrong amino, making an incorrect protein (proteins are the major regulatory mechanism of cells). Also if a start or stop codon is compromised, you could have an incorrect protein made (or no protein made at all) as well. Lentiviruses work in this manner to cause cancer as well. If they incorporate into the DNA in the right area (which for unknown reasons, viruses will incorporate themselves into active genes) , they can cause cancer to develop as a result.

 

[michael200]

TCup: this is in reply to your post #2521. I posted a reply to an article that appears on the Atomic insights blog
http://atomicinsights.com/2011/04/fukushima-nuclear-accident-exceptional-summary-by-murray-e-miles.html

I'll repost here since I don't know if the moderator of the other website has accepted it for general public:

In my humble opinion it would be nice if people could get their facts right:

“You need to hear one more complication in the design. The fuel pool is really two pools separated by a gate. Fuel removed from the reactor goes first into the small, upper pool which is only 20 or 25 feet deep. Later they move the fuel to the big, deep pool. There was apparently only a little fuel in this upper pool at the time of the quake.

This UPPER pool broke. The three-eighths inch steel liner is cracked and will not hold water. The concrete wall in front of this upper pool fell off. Fuel was severely damaged probably by explosion. Temperature profiles measured by helicopters show clumps of hot stuff that must be fuel scattered around the floor area. This scenario is consistent with the numerous reports of fire in unit 4.”

The BWR MKI and MKII reactor building designs have only a single fuel pool for each unit. There is no “small upper pool and lower pool separated by a gate”. I believe that the author is referring to the BWR Mk III design where this is a true statement but has NOTHING to do with the issue a Fukushima concerning fuel pools.
Since there is such conjecture on the events at Fukushima, I’ll throw in my 2-cents: there are currently operators at 30+ BWR plants in the US with their mouths gaping open concerning the OPERATOR ERROR/MANAGEMENT ERROR that allowed any damage at Unit 4. When the earthquake/tsunami hit, the ONLY action that the operators had to take for Unit 4 was to maintain inventory in the spent fuel pool (there was NO fuel in the Reactor pressure vessel). If they needed to do this by injection of seawater – they should have done it. Regardless of the damage caused by the tsunami, there was MORE THAN ADEQUATE time to use a diesel driven fire pump or rig up temporary pumps to add water. My only conclusion on this event is that the Japanese had INADEQUATE planning, procedures and training to deal with a relatively simple issue for Unit 4.

As far as the more serious/difficult scenario for Units 1,2, and 3: My view is as follows: 1. NO PLANT in the world can currently cope with a station blackout greater than 3 days (currently they are at 21 days in japan) without core damage. However, US plants have emergency procedures and mitigating actions to connect temporary pumps/power supplies to ensure restoration of core and containment cooling. I challenge someone to show me the japanese coping studies for SBO 2. Concerning the issue with the uncontrolled release of radioactive materials, which is caused by the loss of secondary containment (blown up Rx buildings) and possible primary containment on Unit 2 (overpressurized to greater than 2x design pressure by OPERATOR ERROR): the japanese either didn’t have installed or didn’t use a hardened containment wetwell vent that is installed at all US MKI BWRs per NRC GL 89-16. The vent was specifically mandated to avoid containment failure if events propogated to the situation where a core melt with high H2 generation could occur. The japanese operators also would have VIOLATED US plant emergency operating procedures /severe accident guidelines to vent the wetwell when the containment design pressure is reached and no containment/core cooling is available (containment design pressure is about 56psig and they reach greater than 120psi containment pressure before they vented).

Time will tell, but the entire situation in japan looks starkly similar to the same issues that occurred at TMI 30 years ago – lack of preparedness and lack of procedural guidance/training. Frankly, I’m a bit concerned at the Ex-navy nuke (Toy PWR)/commercial PWR community bashing of the BWR design and accident mitigation scenarios. Unless they have KNOWLEDGE, they shouldn’t be speculating. Perhaps this is payback for what the BWR designers said about TMI: if the initiating event that caused the TMI meltdown (stuck open primary system relief valve) had occurred at a BWR, then nothing would have happened.

BTW: I’m ex US Navy submarine officer/engineer with 27 years experience in BWR design, testing and operation