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

[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

 

[nikkkom]

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


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

I think first link has incorrect units: Sv/h, should be mSv/h.

 

[a.ua.]

microsieverts per hour

 

[a.ua.]

Maybe someone is interested

Project "New Safe Confinement Construction"


May 24, 2013

Within the NSC Project at the construction site the following works are being performed:
Assembly of the Arch metal structures (for 2nd lifting)
According to the design - 4,097 tons
3,720.63 tons (90.81%) performed
Installation of the Arch roof’s outer cladding:
Surface area of roof cladding before 2nd lifting - 13,952.2 м2.
Overall progress in the Arch outer cladding installation before 2nd lifting – 79%

And
* mounting of a crane (Terex Demag CC8800-1), with the aid of which soon will disassemble the vent pipe, which was one of the symbols of the Chernobyl nuclear power plant.

20 microsieverts where crane

 

[zapperzero]

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!

Again with the irresponsible suggestions? How could you ensure the integrity of the concrete? (don't answer, that's a rethorical question, you can't, not really). How do you plan to check that the corium is still there in 50 years' time? How do you deal with gasses? How do you deal with infiltrated water? (more rhetorical questions, you have no such plan because your thinking does not extend past the present day and CHEAP CHEAP CHEAP).

As expensive and nasty as it is, the corium must be recovered and accounted for, to the limits of what is possible, not to those of what is convenient.

 

[nikkkom]

Again with the irresponsible suggestions? How could you ensure the integrity of the concrete? (don't answer, that's a rethorical question, you can't, not really).

I wonder how Hoover Dam didn't crumble yet.

How do you plan to check that the corium is still there in 50 years' time?

Unsurmountable technical problem. ;)

How do you deal with gasses? How do you deal with infiltrated water?

Hoover Dam. If you don't believe that very large concrete installations can stand for centuries, visit it and touch its concrete.

As expensive and nasty as it is, the corium must be recovered and accounted for, to the limits of what is possible, not to those of what is convenient.

I know where you are coming from: businesses, if left unchecked, do cut corners and cause environmental damage, because it's cheaper that way.

But economics can not be ignored either. There should be a balance.

Tritium from TMI was released into environment. It could have been recovered, it's not impossible. It's just mind-boggligly expensive, while damage from its release is tiny.

Going "to the limits of what is possible" is not always a good idea. For example, it gave us the Space Shuttle, which nearly wiped off all other US launch vehicles, made US lose market share in the space launch business (still not recovered), and saddled US manned space program with $40000/kg to LEO cost for forty years.

It was a marvelous feat of engineering. It was also an economic disaster.

 

[a.ua.]

But at the Hoover Dam, a concrete mix not has Chernobylite.
Chernobylite: specific mineral.
It fused of fuel rods and other parts of the reactor.

 

[zapperzero]

I wonder how Hoover Dam didn't crumble yet.

Not being subjected to neutron embrittlement must have helped, as must have the lack of thermal and mechanical stresses from not being poured around some corium which self-heats and off-gasses. Fun semi-unrelated fact: the Hoover Dam is not made out of concrete, although it does have a nice concrete outer shell.

Going "to the limits of what is possible" is not always a good idea. For example, it gave us the Space Shuttle, which nearly wiped off all other US launch vehicles, made US lose market share in the space launch business (still not recovered), and saddled US manned space program with $40000/kg to LEO cost for forty years.

Funny you should mention the shuttle. It's a textbook example of what you get when your entire engineering mindset is to ignore risks and cut corners.

It was a marvelous feat of engineering. It was also an economic disaster.

The shuttles had a catastrophic failure rate about on par with that of commercial nuclear reactors (1%). Not a marvelous feat at all. Very bad in fact. No one would buy cars if they failed catastrophically that often.

 

[mfb]

Rockets are not cars. A failure rate of 1% is below that of most (all?) other rocket systems.

 

[nikkkom]

Not being subjected to neutron embrittlement must have helped, as must have the lack of thermal and mechanical stresses

You sure Hoover Dam isn't under "a bit" of stress from the water it holds in the reservoir upstream? Nearly 30 atm at the lower part of the dam.

The shuttles had a catastrophic failure rate about on par with that of commercial nuclear reactors (1%). Not a marvelous feat at all. Very bad in fact.

No, it isn't too bad in that regard. Most launch vehicles to date have demonstrated reliability under 99%.
Shuttle's main problems are enormous cost of operation and low achievable flight rate.

 

[zapperzero]

You sure Hoover Dam isn't under "a bit" of stress from the water it holds in the reservoir upstream? Nearly 30 atm at the lower part of the dam.

All of it is static compression load.

No, it isn't too bad in that regard. Most launch vehicles to date have demonstrated reliability under 99%. Shuttle's main problems are enormous cost of operation and low achievable flight rate.

There is this report by Feynman that you should read. But I'm not sure you have the patience, so here's something you can listen to instead.