Sådan byggede de stål-sarkofagen til Tjernobyl

I dag får den havarerede reaktor det, der kaldes 'den største, bevægelige landbaserede konstruktion, der nogensinde er bygget'. 36.000 ton stål på skinner i 40 timer. Se hvordan den blev bygget.

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Hvem skal bestråles under nedbrydningen? Kan en stålkappe holde strålingen inde? Jeg troede at der skulle bly til det.

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Jeg er (heller) ikke civilingeniør med speciale i atomkraft, og synes at Finn stiller to meget fine spørgsmål.

Lad dog være med at nedstemme ham, men svar eller henvis til læringsmulighed.

Som jeg forstår det, skal der foregå en hel masse arbejde meget tæt på reaktoren, og det siger billedserien intet om -- hverken om hvordan de lodrette sider monteres efter "buen" er flyttet, eller om hvordan den gamle sarkofag demonteres.

Er det robot-arbejde? Det ville være fantastisk, men nok desværre bogstavelig talt...

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Spørgsmålene er ret negativt ladet (da afsenderen sikkert er ikke positiv overfor kernekraft), og der er ikke gjort det store for at finde information.

Den tidligere sakrofag og den nye containment bygning og formål beskevet i en rimmeligt tilgængeligt (engelsk) sprog (eller kan man jo bruge google translate): http://chernobylgallery.com/chernobyl-disa...

Den nye bygning formål er at beskytte den eksisterende bygning indtil man kan starte en organiseret oprydning, og dermed holde det fyske materiale på stedet/indenfor bygning.

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Jeg er bestemt ikke ekspert, men tror det primære formål er at holde støv indekapslet inde i sarkofagen. Området omkring reaktoren er ikke voldsomt radioaktivt, men hvis du indånder støv så kan alpha stråling skade kroppen indefra. Den gamle betonkonstruktion er ved at falde sammen, og det kan resultere i en farlig støvsky som kan holdes inde i sarkofagen.

Ret mig gerne hvis jeg tager fejl, god dag :-)

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@jacob bonde. Tak for ref. Desværre giver den et udmærket indblik i ulykken i 86 og en god beskrivelse af konstruktionen af den nye overdækning. Derimod giver den ikke svar på mine spørgsmål. Jeg kan ikke se noget negativt i dem, og indtil ulykken var jeg nok mest for atomkraft som energikilde, men efter er jeg nok blevet betænkelig. Jeg synes ikke vi er dygtige nok eller forsigtige nok, og vi er bestemt ikke gode nok til at forudse og tage højde for mulige farer. Se hvad der er skete i Japan. Før vi har en rimelig sikker viden om hvad man kan/vil gøre med resterne af værkerne, så burde man ikke svine hele verden til med kraftværker, som vil ligge og stråle efter brug eller nedtagningen. Se bare med vores egen lille Risø.

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To shield against gamma radiation you need MASS. Lead is convenient as it is very dense so that you need a smaller size of lead than fx steel or concrete but the same mass thickness of concrete or steel will still shield radiation to the same extent.

I haven't kept up much with Chernobyl, as my speciality in RP is in University Radiation Protection and, while I have rather more knowledge of reactors than "the man in the street", I'm not an expert.

Now part of the problem Finn is that you are asking the wrong question. As I understand it there is actually very little radiation issue nowadays from the reactors at Chernobyl, rather the issue is about radioactive materials, in particular radioactive dust. For some reason that I have never understood, in my many years in radiation protection no journalist has ever discovered the difference between the two, so they continue to write "RADIATION" when they mean RADIOACTIVITY!

The two are different. In English we use the term "light" to mean both the light which is illuminating us and the surrounding area AND the electrical item which actually gives off light when turned on. We say "turn the light on". This mistaken use of language gives the same mental mistakes as mixing up radiation and radioactivity.

Now because there are a number of different radiations - alpha, beta, gamma, neutron med flere, all of which have different shielding requirements - alpha radiation can be shielded with a cigarette paper! - huge confusion reigns for those who don't know any more than journalism gives them.

The very big problem is that although currently gamma radiation from Chernobyl is not a big issue, there are large quantities of alpha emitting radionuclides present which could easily be released very widely if the old sarcophagus collapses. The primary purpose of the new steel cover, as I understand it, is to retain the entire release of radioactives should the old sarcophagus collapse; shielding from radiation is, I believe, not it's primary purpose, so the use of extra mass for shielding is not such a big issue.

The problem with alpha emitting radioactive materials is that, since the radiation can be shielded so easily, it necessarily deposits very large amounts of energy very quickly in the surrounding material. If you get alpha emitting radionuclides into your body, in intimate contact with tissue (and biology often dumps the particular heavy metals involved in this sort of mix into the growing area of the bones!) then a very high level of irradiation of tissue will occur and great damage to those tissues. No we definitely do NOT want dust loosed into the air and blown all over Europe if the sarcophagus collapses, nor even if it can be taken down safely.

One last thing - you may be surprised that one of the important uses for depleted Uranium is for shielding gamma radiation where space for the shielding is a problem. It's even denser than lead and a thinner layer of lead outside it (or even the structural steel of the equipment itself) is all that is needed to shield the weak radiation from the Uranium.

Sorry to have to write in English. While I read and understand spoken Danish fluently, my thinking patterns are entirely based on the English language - my mother tongue. When I try to write a complicated reply like this, my thinking patterns become incomprehensibly English to native Danes - even my Danish wife who is unbelievably fluent in English and has been with me from my very first Danish word to my current fluency often cannot understand it - very frustrating!

Regards

David Walland

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