Chernobyl Chernobyl Reactors 1-3: Fuel Removal After 2000 Shutdown

[Kutt]

After the Chernobyl NPP was fully and permanently shut down in 2000, did they remove the fuel from reactors 1-3 as well as from the spent fuel pools?

Construction on reactors 5-6 was canceled after the meltdown in 1986.

 

[Shisnu]

As far as I know, reactors #1, #2, and #3 still have some fuel contained within, as well as some in the spent fuel ponds. Over the years, a number of proposed contracts for defueling and transportation of the spent fuel to a long term storage facility have fallen through due to budgets overrunning and the difficulty in dealing with the politics of the region (Western companies tend to have a hard time overcoming the bureaucracy, as Ukraine likes to appear to be pro-Russian rather than pro-Western).

Recently there's been an increase in pressure from the IAEA as well as the Chernobyl-Fukushima human interest group to completely decommission the site. From what I understand, the current plan is to finish the previous abandoned ISF-2 storage site after the Sarchophagus replacement, and then defuel 1 - 3 (no idea how they will attempt to decommission number 4 though!).

That's an awesome picture btw, here's one of the scrapped reactors 5 and 6 I took whilst I was there, complete with cranes and half-finished buildings where construction was suddenly halted. Spooky!

 

[rollingstein]

Love that pic.

 

[Kutt]

As far as I know, reactors #1, #2, and #3 still have some fuel contained within, as well as some in the spent fuel ponds. Over the years, a number of proposed contracts for defueling and transportation of the spent fuel to a long term storage facility have fallen through due to budgets overrunning and the difficulty in dealing with the politics of the region (Western companies tend to have a hard time overcoming the bureaucracy, as Ukraine likes to appear to be pro-Russian rather than pro-Western).

Recently there's been an increase in pressure from the IAEA as well as the Chernobyl-Fukushima human interest group to completely decommission the site. From what I understand, the current plan is to finish the previous abandoned ISF-2 storage site after the Sarchophagus replacement, and then defuel 1 - 3 (no idea how they will attempt to decommission number 4 though!).

That's an awesome picture btw, here's one of the scrapped reactors 5 and 6 I took whilst I was there, complete with cranes and half-finished buildings where construction was suddenly halted. Spooky!

I was watching a video where someone mentioned a hypothesized plan to build a giant dome over reactor 4 and somehow completely dismantle the ruins of the shattered reactor building (very much in the same manner that they did with the rubble of the world trade centers) using giant cranes and robotic machines, and then ship the wreckage to an off-site location so it can be "dealt with.' They also mentioned that this process could literally take a few centuries.

There was also another proposed plan of burying the reactor ruins with millions of tons of sand and concrete and leave it like that forever..

Chernobyl is old hat, the new problem is dealing with Fukashima Daiichi in Japan. Which is said to be even more dangerous and highly radioactive than the Chernobyl exclusion zone. Most of the radioactive core material is contained within Chernobyl's "sarcophagus" and it is relatively safe for people to visit "the zone" while wearing the proper protective equipment and respirators, for a very short period of time.

The Fukashima exclusion zone is much "hotter" than Chernobyl because it is a fairly recent event and has not yet been completely contained. Fortunately, the severity and radiological release of Fukashima was much less than 1/10th that of Chernobyl according to this televised documentary.

 

[Shisnu]

Well they in the process of building a replacement sarcophagus to fit over the rather hastily built one. It is being built on-site, just a few hundred yards form reactor #4, constructed on rails so it will simply 'slide' over the old structure. In the last couple of months they announced that the first stage had been completed, the basic frame of the sarchophagus mk 2 now up. The company in charge is called 'Novarka' (google 'em to see some sarchophagus pics, it's pretty cool!).

The final plan will probably be a combination of both your suggested ideas. Using radiation-resistant robots to try and clear away as much of the fuel and high-level waste as possible, the last stage will probably be to use concrete and seal the building completely. This could in all probability decrease the dose rate outside the building to around background levels! At the moment the dose rate in the air close to the NPP is around 0.9 μSv/hr (about 3 times normal background). That's mainly due to the reactor itself. The dose rate on the ground is higher in places (hot spots due to contamination from the explosion and the cloud). See a couple more pics to highlight this.

I wouldn't say that Chernobyl is old hat, at least not to the international nuclear community and to the people of Ukraine. I also don't know who said that the Fukushima exclusion zone is more 'dangerous' or 'hotter' than the Chernobyl one, but let's just agree that qualitative and emotive expressions like these don't really have any place in a scientific discussion ;).

Since the CNPP exclusion zone is actually a hive of activity (about 3,000 scientists and engineers living there), as well as being home to some 300 settlers who have moved back in (oh and don't forget the Chernobly national park, a wildlife haven for animals), it's certainly not as bad as you make out. You don't need protective clothing or respirators, and in most place the dose rate is actually LOWER than in cities, since you don't get nearly the same amount of traffic.

The only comparison I can make between Fukushima and Chernobyl that is related to your original question is that much of the same robotic technology and containment procedures will be applied between the two. There's a great deal of scientific collaboration in this regard.

 

[nikkkom]

The current state of Chernobyl site very much looks like a giant permanent source of kickbacks.

For example:

As far as I know, reactors #1, #2, and #3 still have some fuel contained within.

Of course! As long as it is there, all parties involved can continue to demand more $$$ for the ongoing cleanup. I bet they love the "ongoing" part, all of them: Ukrainian bureaucrats, Western companies, Ukrainian companies.

I was watching a video where someone mentioned a hypothesized plan to build a giant dome over reactor 4 and somehow completely dismantle the ruins of the shattered reactor building

Another billion-gobbling plan. As if we *need* that reactor dismantled. What for? Someone is eager to grow plutonium-laced veggies on the nearby fields?

The basements and ground floors of Chernobyl Unit 4 can be just filled with concrete, completely covering all corium and heavily contaminated structures; then the remaining structures on top can be dismantled. But that is way too CHEAP!

 

[nikkkom]

Using radiation-resistant robots to try and clear away as much of the fuel and high-level waste as possible, the last stage will probably be to use concrete and seal the building completely.

Why bother with the step 1, considering how costly it is, and that it will inevitably disturb the material and spread around some radioactive dust?

What's the problem with leaving melted fuel and high-level waste where it is now?

 

[nikkkom]

Chernobyl is old hat, the new problem is dealing with Fukashima Daiichi in Japan. Which is said to be even more dangerous and highly radioactive than the Chernobyl exclusion zone.

Wrong. Chernobyl's contaminated area is bigger, and worse than Fukushima's.

Most of the radioactive core material is contained within Chernobyl's "sarcophagus" and it is relatively safe for people to visit "the zone" while wearing the proper protective equipment and respirators, for a very short period of time.

Wrong. Chernobyl reactor *burned in the open for days on end*. Ergo, core material, including less-volatile elements such as plutonium, americium, was distributed around in the form of microscopic ash particles.
In Fukushima, melted cores were contained inside reactor buildings. Only volatiles (caesium, strontium) escaped. Plutonium escaped in very small amounts.

The Fukashima exclusion zone is much "hotter" than Chernobyl

Wrong.

because it is a fairly recent event and has not yet been completely contained.

What does "contained" even means? Cs-137 is in the soil and wood now at both sites. You can not "contain" that.

 

[Shisnu]

Why bother with the step 1, considering how costly it is, and that it will inevitably disturb the material and spread around some radioactive dust?

What's the problem with leaving melted fuel and high-level waste where it is now?

1) A new sarcophagus would prevent contamination to the outside whilst defueling is carried out.

2) At the moment it's not exactly in a safe state. Since high-level waste will remain active for thousands of years, the nuclear industry and the public want assurances that it won't leak out of its container and find its way into a major river (the Dnieper in the case of the CNPP, which flows through Kiev).

The CNPP sarcophagus is not such a container, it was hastily constructed and has required constant maintenance over the years. Simply filling everything in with concrete provides absolutely no guarantee that you prevent further contamination over time. The entire building is slowly collapsing and despite a lot of remote viewing we don't yet have a clear picture (AFAIK) of the locations of all the fuel hot-spots inside.

You also can't overlook the socio-environmental implications of leaving Chernobyl as it is, a constant source of fuel for the anti-nuclear brigade. Imagine a fully decommissioned Chernobyl, with the fuel removed and the on-site background dose reduced to normal levels. That would show the world that the nuclear industry is the only energy industry that is fully capable of true environmental remediation.

This thing has to be done properly, not the half-arsed Soviet-era guesstimations that caused the accident in the first place.

I should also mention that it's not just the management of the CNPP that goes on in the zone, there's also a great deal of environmental research.

 

[a.ua.]

http://www.chnpp.gov.ua/index.php?option=com_content&view=article&id=230&Itemid=101&lang=ru

You can watch the construction of a new "sarcophagus" (new safe konfeyment on our own. НБК )
through this online camera.

 

[a.ua.]

http://www.chnpp.gov.ua/index.php?lang=en

This is the official site of the Chernobyl nuclear power plant.

 

[a.ua.]

A lot of information (videos, photos, forum) about the Chernobyl katostrofy here.
http://pripyat.com/en

And also here
http://chornobyl.in.ua/en/

 

[nikkkom]

1) A new sarcophagus would prevent contamination to the outside whilst defueling is carried out.

2) At the moment it's not exactly in a safe state.

Yes. But I am not saying "let's do nothing and leave it as is".

Simply filling everything in with concrete provides absolutely no guarantee that you prevent further contamination over time.

First, not "simply", but after careful design work which will ensure that the right kind of concrete is used, that it will not be vulnerable to weathering, and so on.

And secondly, how turning basements in a monolithic slab of rock "provides absolutely no guarantee"? It is definitely way better than current state.

Imagine a fully decommissioned Chernobyl, with the fuel removed and the on-site background dose reduced to normal levels.

...while hundreds of square kilometers around it will be still too contaminated to allow permanent habitation, and too costly to clean up.

In other words, even is Chernobyl site itself will be cleaned up to a state of pristine clean patch of grass, it will be still useless economically.

I think that such a PR operation is "a little bit" too costly.

That would show the world that the nuclear industry is the only energy industry that is fully capable of true environmental remediation.

We are 26 years after disaster and it's still nowhere near that state. That tell a lot about nuclear industry, and about Ukrainian government.

Having a first-hand knowledge about said government, I don't expect prospects of rapid changes; I am sure massive squandering of money while making some progress at glacial pace will continue.

 

[Kutt]

Yes. But I am not saying "let's do nothing and leave it as is".



First, not "simply", but after careful design work which will ensure that the right kind of concrete is used, that it will not be vulnerable to weathering, and so on.

And secondly, how turning basements in a monolithic slab of rock "provides absolutely no guarantee"? It is definitely way better than current state.



...while hundreds of square kilometers around it will be still too contaminated to allow permanent habitation, and too costly to clean up.

In other words, even is Chernobyl site itself will be cleaned up to a state of pristine clean patch of grass, it will be still useless economically.

I think that such a PR operation is "a little bit" too costly.



We are 26 years after disaster and it's still nowhere near that state. That tell a lot about nuclear industry, and about Ukrainian government.

Having a first-hand knowledge about said government, I don't expect prospects of rapid changes; I am sure massive squandering of money while making some progress at glacial pace will continue.

You're right, even if they did somehow completely clear and decontaminate the site and turned it into a big green field of grass, that piece of land would have little to no economic value and would be a complete waste of effort and money.

The Chernobyl exclusion zone is a bustling haven for variously environmental and scientific research. It would probably be a better decision to just build a secondary sarcophagus to reduce radiation levels in Pripyat and surrounding areas to normal background levels.

The only place in Chernobyl that has DANGEROUS levels of radiation is inside the reactor block itself. All of the nuclear fuel is contained entirely inside the sarcophagus and poses no environmental threat.

 

[nikkkom]

It would probably be a better decision to just build a secondary sarcophagus to reduce radiation levels in Pripyat and surrounding areas to normal background levels.

?!

The background outside Unit 4 isn't coming from Unit 4.

Fuel and debris inside Unit 4 needs to be covered not so much in order to shield its emissions, but to prevent it from weathering and spreading around in the form of dust or dissolved salts in rain- and groundwater.

 

[Shisnu]

Nikkkom, your concrete plan is still impractical it makes no attempt to account for the fuel inventory.

As I said before, we don't know how far the fuel has penetrated the concrete bedrock and its subsequent distribution, so even if you fill the entire building with grade A triple rad protection concrete (not a cheap idea BTW ) you can't guarantee you've prevented long-term contamination.

Criticising the socio-environmental benefits on economic grounds also is a weak argument, as it digresses from my point.

I would be inclined to say this thread seems to have dissolved into sweeping generalisations, misinterpretations, and ill-informed opinions. I would recommend reading a.ua.'s links (thanks for those!) as it may help you to look at things a little more objectively.

Finally:

The only place in Chernobyl that has DANGEROUS levels of radiation is inside the reactor block itself.

I posted a picture above that showed a gamma dose rate on a soil hotspot of 13.27 μSv/hr. The nuclear industry considers this a 'dangerous level'. Whilst much of the exclusion zone is low in dose rate, these hotspots are what make the area unsafe (from a radiological point of view, there are other dangers).

 

[nikkkom]

Nikkkom, your concrete plan is still impractical it makes no attempt to account for the fuel inventory.

As I said before, we don't know how far the fuel has penetrated the concrete bedrock and its subsequent distribution, so even if you fill the entire building with grade A triple rad protection concrete (not a cheap idea BTW ) you can't guarantee you've prevented long-term contamination.

Water isolation become an insurmountable problem? I don't think so.

While you worry about long-term contamination, today a bird can fly into Sarcophagus through one of numerous holes and land on the (still highly radioactive) Upper Biological Shield of the former 4th reactor.

Today, rainwater pours into Sarcophagus, and then OUT of it, measured in TONS.

It's been 26 *years*, and not much have been done since 1990 (apart from billions stolen).

I would be inclined to say this thread seems to have dissolved into sweeping generalisations, misinterpretations, and ill-informed opinions. I would recommend reading a.ua.'s links (thanks for those!) as it may help you to look at things a little more objectively.

Please be informed that I am an Ukrainian. I *lived* in Ukraine during and after the disaster. I had a coworker who used to work in one of the firm which participated in ongoing cleanup effort. I asked him about his former work. He reaffirmed my worst suspicions about the ways things are done there.

I would risk stating that I know what I'm talking about.

 

[Shisnu]

I'm not sure what you're getting at, from what I understand, the new sarcophagus is designed to correct the problems you have mentioned.

I'm not concerned with your comments such as "billions stolen", as they don't really add anything to the discussion and I'm only interested in the science and the engineering. All I've been trying to say is that I think the best decommissioning plan would be to use this new sarcophagus to contain any airborne contamination whilst the high-level waste is moved to a new site specifically designed to prevent further contamination. In my view this would allow for the greatest remediation of nuclear contamination in the Chernobyl area.

Also please note that my comments about generalisations and ill-informed opinions were not necessarily directed at you in particular. I believe I gave an example of what I was talking about in my previous post.

I think we can at least agree that the handling of the Chernobyl disaster area has always been, and still is, far from ideal?

 

[a.ua.]

Shisnu

That's an awesome picture btw, here's one of the scrapped reactors 5 and 6 I took whilst I was there, complete with cranes and half-finished buildings where construction was suddenly halted

Sometimes, when a strong wind they spin and it seems that the work continues.

If it were not severe pollution (especially actinides) mechanisms to be dismantled Metal scrap.

 

[winnie_t]

kutt,

can i ask where is that image from?

 

[nikkkom]

I'm not sure what you're getting at

I'm saying that from the Ukrainian citizens' POV, the Chernobyl cleanup saga needs to finish (I would say it had to be finished by about 2000). It's *their taxes* being squandered there.

I think the best decommissioning plan would be to use this new sarcophagus to contain any airborne contamination whilst the high-level waste is moved to a new site specifically designed to prevent further contamination.

In a theoretical world where all involved parties honestly want to clean up this mess and be done - yes.

I think we can at least agree that the handling of the Chernobyl disaster area has always been, and still is, far from ideal?

Yes.

 

[a.ua.]

nikkkom

I would say it had to be finished by about 2000

Why this time, why not 2016 or 1995?
Or any other time.

 

[nikkkom]

nikkkom
Why this time, why not 2016 or 1995?
Or any other time.

During the first few years after the disaster radioactivity, and accompanied dangers to workers' health, is decreasing noticeably.

For example, initially Cs-134 constitutes about half of radioactive Cs inventory (the other half is Cs-137), but its half-life is only 2 years. It makes sense to wait for it to decay. In 10 years, it will decay to 1/64 of initial level.

After ~10 years, waiting more stops making sense.

It's not just Cs-134. See attached file. After 10 years, radioactivity decrease of fission products has a plato. While weathering of ruins doesn't.

 

[Kutt]

kutt,

can i ask where is that image from?

Sorry, I tried searching but for some reason I can't find it now.

But here's this picture of a mutant tree just outside of the reactor.

 

[nikkkom]

Sorry, I tried searching but for some reason I can't find it now.

But here's this picture of a mutant tree just outside of the reactor.

No, it isn't a mutated tree. The tree is even older than Chernobyl NPP.

 

[Kutt]

No, it isn't a mutated tree. The tree is even older than Chernobyl NPP.

Oh, I thought that tree grew around high levels of radiation and thus was deformed.

Aren't the trees in the "red forest" outside of Chernobyl highly irradiated and malformed, and the trees turned red after the disaster?

 

[a.ua.]

nikkkom

In 10 years, it will decay to 1/64 of initial level. After ~10 years, waiting more stops making sense. It's not just Cs-134.

In fact, the contribution of cesium 134 is not big enough.
And at the time, and now, the bulk of radiation from strontium and cesium 137.(and cerium in the past)
Besides alpha emitters are the big problem.
They have a very long half life.
70 - 100 years It is safest to wait

 

[winnie_t]

Oh, I thought that tree grew around high levels of radiation and thus was deformed.

Aren't the trees in the "red forest" outside of Chernobyl highly irradiated and malformed, and the trees turned red after the disaster?

yes I would guess that's mutated. Didn't some pine needles grew up too 4.5cm.
Amazing pictures!

(and thanks kurt for the searching. you have any more interesting picture?)

 

[winnie_t]

as we are talking about the radioactivity, I wonder if it would differ at various height? would there be any data on how it vary as it goes higher into the atmosphere?

 

[nikkkom]

nikkkomIn fact, the contribution of cesium 134 is not big enough.

I don't think so (unless you mean "...in Chernobyl today").

In Fukushima plume, Cs-134 activity was almost exactly the same as Cs-137 at the beginning. Waiting it out cuts gamma exposure in half.

I would hazard to guess that Chernobyl's proportion of Cs-134/Cs-137 wasn't terribly different from Fuku.

And at the time, and now, the bulk of radiation from strontium and cesium 137.(and cerium in the past)
Besides alpha emitters are the big problem.

If we are talking specifically about health of today's Chernobyl Unit 4 cleanup workers, then no. Alpha and beta emitters can be counteracted with careful dust control. Gamma can't be.

 

[Kutt]

I don't think so (unless you mean "...in Chernobyl today").

In Fukushima plume, Cs-134 activity was almost exactly the same as Cs-137 at the beginning. Waiting it out cuts gamma exposure in half.

I would hazard to guess that Chernobyl's proportion of Cs-134/Cs-137 wasn't terribly different from Fuku.
If we are talking specifically about health of today's Chernobyl Unit 4 cleanup workers, then no. Alpha and beta emitters can be counteracted with careful dust control. Gamma can't be.

Many of the radionuclides dispersed from Chernobyl and Fukashima have half-lives of tens of thousands of years.

Uranium and Plutonium are just two of them.

 

[Shisnu]

Many of the radionuclides dispersed from Chernobyl and Fukashima have half-lives of tens of thousands of years.

Uranium and Plutonium are just two of them.

It's worth pointing out that if a radionuclide has a very long half life, then it isn't very active, and therefore isn't as dangerous ;)

 

[nikkkom]

Many of the radionuclides dispersed from Chernobyl and Fukashima have half-lives of tens of thousands of years.

In fact, there are only a few radionuclides which are volatile enough to spread far and wide after meltdowns. The rest are less volatile.

Google for Chernobyl fallout maps. You will see that Cs-137 contamination area is the largest, next is Sr-90, and it is much smaller.

Plutonium and americium are much smaller still, to the point that you can ignore them: any place with significant plutonium contamination will have A LOT of Cs-137 and be uninhabitable because of that alone.

 

[Kutt]

In fact, there are only a few radionuclides which are volatile enough to spread far and wide after meltdowns. The rest are less volatile.

Google for Chernobyl fallout maps. You will see that Cs-137 contamination area is the largest, next is Sr-90, and its much smaller.

Plutonium and americium are much smaller, to the point that you can ignore them: any place with significant plutonium contamination will have A LOT of Cs-137 and be uninhabitable because of that alone.

What about MOX fuel, one of the Fuku reactors contained MOX. Apparently it is supposed to be more dangerous than plutonium.

 

[nikkkom]

What about MOX fuel, one of the Fuku reactors contained MOX. Apparently it is supposed to be more dangerous than plutonium.

MOX is a very dangerous chemical element #133 ;)
Even Wikipedia is afraid to have an article about it, don't try to find and read it there ;)

 

[a.ua.]

nikkkom

I would hazard to guess that Chernobyl's proportion of Cs-134/Cs-137 wasn't terribly different from Fuku.

No.
The ratio of cesium (134/137) in Chernobyl 0.65 - 0.7
In Fukushima 0.85- 0.9
In this math is important initial figure. And she is very large.
As you can see in 2007 the level of gamma roof Shelter still great.
3 hours and dialed dose
The radiation level in the "Central Hall" is 12 Sv,
in some other places, there is a residual fuel 0.1 - 6 Sv

 

[nikkkom]

>> I would hazard to guess that Chernobyl's proportion of Cs-134/Cs-137 wasn't terribly different from Fuku.

No.
The ratio of cesium (134/137) in Chernobyl 0.65 - 0.7
In Fukushima 0.85- 0.9

What "no"? It is not too far from 1:1. Cs-134 in both cases was (in Fukushima, still is) a significant contribution to gamma fields.

 

[Kutt]

MOX is a very dangerous chemical element #133 ;)
Even Wikipedia is afraid to have an article about it, don't try to find and read it there ;)

WOW! Even Wikipedia is afraid to talk about it?

Where can I find detailed info about MOX fuel in relation to Fukushima?

 

[russ_watters]

MOX is a very dangerous chemical element #133 ;)
Even Wikipedia is afraid to have an article about it, don't try to find and read it there ;)

[cough]
http://en.wikipedia.org/wiki/MOX_fuel

 

[a.ua.]

What "no"? It is not too far from 1:1. Cs-134 in both cases was (in Fukushima, still is) a significant contribution to gamma fields.

I think, 0.65 and 0.9 are different.

Moreover, there are large differences in the size of the physical size of the particles of cesium.
In Fukushima plume they are minimal (removal in pairs).
They are more mobile and quickly washed away by rain into the sea.
In general, 15 years later, the situation with radiation in Fukushima exclusion zone will be much better than in Chernobyl.

 

[Kutt]

I think, 0.65 and 0.9 are different.

Moreover, there are large differences in the size of the physical size of the particles of cesium.
In Fukushima plume they are minimal (removal in pairs).
They are more mobile and quickly washed away by rain into the sea.
In general, 15 years later, the situation with radiation in Fukushima exclusion zone will be much better than in Chernobyl.

How much contaminated radioactive material leaked from Fukushima and into the sea?

 

[nikkkom]

I think, 0.65 and 0.9 are different.

Please learn to follow your own train of thought.

You asked me why I think Chernobyl needed to be cleaned up by about year 2000.

I explained to you that in my opinion the first 10 years could be reasonably used to "wait out" shorter-lived contaminants, and gave you an example of such contaminant, Cs-134, which is (a) volatile and thus a lot of it escaped, (b) abundant, and (c) half-life 2 years.

Why do you jump to Fukushima topic now?

Why do you bicker about exact Cs-137/134 ratio? It *isn't essential* to my argument whether it was 1:1 or 1:0.6, 1:0.6 still results in very significant gamma contribution from Cs-134!

 

[nikkkom]

How much contaminated radioactive material leaked from Fukushima and into the sea?

That is the least problematic part of the Fukushima contamination. Pacific Ocean is *BIG*.

Measurements show that by now, all leaked contamination has been diluted far below the natural radioactivity level of seawater (10-15 Bq/l depending of the salinity), most of which comes from Potassium-40.

Japanese were lucky. Most of the time, wind was blowing Fukushima's gases and steam out to the ocean.

 

[a.ua.]

Please learn to follow your own train of thought.

You asked me why I think Chernobyl needed to be cleaned up by about year 2000.

OK, I understand you.
Maybe I was a little boring, do not get angry.:)
However, they did start the second phase of the elimination in 2000,
But this is not the reduction of radiation levels.

That is the least problematic part of the Fukushima contamination. Pacific Ocean is *BIG*.

+1

 

[Kutt]

That is the least problematic part of the Fukushima contamination. Pacific Ocean is *BIG*.

Measurements show that by now, all leaked contamination has been diluted far below the natural radioactivity level of seawater (10-15 Bq/l depending of the salinity), most of which comes from Potassium-40.

Japanese were lucky. Most of the time, wind was blowing Fukushima's gases and steam out to the ocean.

Did any of the radioactive contamination from Fukushima reach the west coast of the United States across the pacific ocean via the prevailing winds?

I read that this radiation is not at high enough levels to be considered a health risk.

 

[nikkkom]

Did any of the radioactive contamination from Fukushima reach the west coast of the United States across the pacific ocean via the prevailing winds?

Sure! "Some" radioactive contamination from Fukushima exists even on the desk you are sitting at - regardless where that desk is.

In one gram of Cs-137 there are about 4400 billions of billions (4.4*10^21) of atoms. That's a HUGE number. Evenly distributed over surface of Earth, it is about 8.5 million atoms per every square meter.

Fukushima released way more than one gram of Cs-137.

I bet you wanted to ask a different question :)

I read that this radiation is not at high enough levels to be considered a health risk.

Exactly. In US, Fukushima's contamination is WAY below levels of any detectable effect on health.

It is useful to remember a few numbers when you want to make sense of contamination levels.

Seawater's radioactivity is 10-15 Bq/L.

Human body, on average, contains 4000 Bq of K-40 radioactivity (that is, ~50 Bq/kg). And 1200 Bq of C-14.

There is an edible nut (some "Brazil nut") which has 444 Bq/kg. It is probably the upper end of what can be considered "natural levels of radioactivity in food". Useful when you read about e.g. the rules Japan now establishes for allowable activity in their food.

(Anyone knows what's an average natural soil radiation in Bq/m^2, and what is the typical variability depending on soil type?)

 

[Kutt]

Currently, what are the radiation readings at the Fukushima plant itself? Especially outside the shattered reactor buildings. Is it much higher than the Chernobyl exclusion zone?

 

[a.ua.]

Notice about abnormal situation

12.02.13. Partial failure of the wall slabs and light roof of the Unit 4 Turbine Hall occurred at 14.03 above non-maintained premises on the level 28.00 meters in the axes 50-52 from range A to rage B. The area of damage is about 600m2. This construction is not critical structure of the "Shelter" object.
There is no violation of limits and conditions of "Shelter" object safe operation in accordance with the technological regulations. There are no changes in radiation situation at ChNPP industrial site and in Exclusion zone. There were no.
http://www.chnpp.gov.ua/index.php?o...7-04-25&catid=28:nssreports&Itemid=11&lang=en

 

[a.ua.]

Work is being completed on clearing the in the local area "Shelter"

http://www.chnpp.gov.ua/index.php?o...340:-qq&catid=28:nssreports&Itemid=11&lang=ruIn addition

Today, on the 20 of February, were resumed the activities on assembling the NSC metal structures and Arch cladding, which are performed by personnel of Joint Venture “Novarka” within free access area. The “Novarka” management informed the SSE ChNPP about this in written form on February 19, 2013.
http://www.chnpp.gov.ua/index.php?o...d&catid=94:news&Itemid=11&lang=en

 

[LabratSR]

Currently, what are the radiation readings at the Fukushima plant itself? Especially outside the shattered reactor buildings. Is it much higher than the Chernobyl exclusion zone?

http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/f1-sv2-20130307-e.pdfAlso http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/f1-sv-20130225-e.pdf