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Nuklearna kriza u Japanu: šta se zaista dešava?

13 Mar

Sve oči uprte su ka nuklearkama u Japanu. Saopštenja nisu konzitentna između Vlade Japana i Tepco-a, kao i svetskih medija i Međunarodne agencije za nuklearnu energiju (IAEA) i WNN-a.

Danas na CNN-u voditelj nije ispuštao reč Černobilj iz usta. Šta se tačno dešavalo do sada i koji su moguću scenariji? Bez apokaliptične priče.

Ovaj tekst objavljujem jer, kao i ceo svet, ovih dana netremice pratim vesti iz Japana. Međutim, čak i saopštenja japanskih zvaničnika nisu usaglašena — Vlade Japana, Ministra za vanredne situacije i kompanije Tepko (Tokio Electric Power Co.), u čijem je vlasništvu elektrana i koja njome upravlja. Vodeći domaći sajtovi prenose agencijske vesti, brutalno prevedene na srpski, te sam juče u Blicu pročitao da je do eskplozije došlo usled „mešanja hidrogena i oksidžena„. Međutim, i vodeće svetke medijske kuće objavljuju pogrešne podatke. Tako na CNN web-stranici opisuju rad reaktora broj 1 nuklearke Fukušima, sa ilustracijom procesa — gde se opisuje rad nuklearke drugog tipa (Fukušima je BWR, na slici je bio reaktor tipa PWR). O skraćenicama će biti reči u daljem tekstu.

Prizivaju se najgora iskustava: Černobilj u Ukrajini, gde se desilo potpuno topljenje jezgra; mnogi u hronologiji havarija zaboravljaju na Ostrvo tri milje u Pensilvaniji, SAD (Three Mile Island), gde se 1979. dogodilo delimično topljenje jezgra. Videćemo koliko je situacija u Japanu slična ovim havarijama i da li je ekvivalentna atomskoj bombi, što sam takođe pročitao u tiražnoj stranoj štampi.

Izdvojio bih još nekoliko crtica: reaktori 1 i 3 u pogođenoj nuklearki Fukušima u Japanu bili su spremni za trajno isključivanje i demontažu na leto ove godine. Inače su stari više od 30 godina i radni vek im je istekao. Projektovani su da izdrže zemljotres do 8,2 stepena po Rihterovoj skali. Zemljotres je bio 8,9 stepeni, što je oko 7 puta jači udar (Rihterova skala je logaritamska)! Nakon 7 puta jačeg udara i cunamija, koji nije predviđen, praćenim serijom udara od 6-7 stepeni narednih dana, počele su da se dešavaju nepredviđene okolnosti. Tehnologija rekatora je 50 godina stara, u pitanju je General Electric model izgrađen u Japanu, koji je kako-tako preživeo najveći zemljotres i cunami u poslednjih 100 godina!

Tekst koji sledi ljubazno mi je ustupio profesor Beri Bruk (Barry Brook), kojem se zahvaljujem. Prikaz je napisao Dr Josef Oehmen, dobar poznavalac nemačke nuklearne industrije, naučnik i predavač na Tehnološkom institutu u Masačusetsu (MIT) iz Bostona. Napisan je 12. marta, i sažima sve raspoložive podatke do tog trena. Bitno je razumeti rad nuklarne centrale i sisteme zaštite, kako bi se izbegao nepotrebni strah od nepoznatog. Najbolje smo ga osetili u Srbiji 1999. u vreme pomračenja Sunca, kada su ulice u celoj zemlji bile puste, šaloni spušteni, roletne navučene — iz straha od kraja sveta.

Tekst ostavljam u izvornom obliku, bez prevoda. Ukoliko je čitanje materijala na engleskom poteškoća, savetujem korišćenje Google automatskog prevodioca. Kliknite ovde i otvoriće se novi tab sa (rogobatnim) prevodom (koji će „prevesti“ sa srpskog na sprski prvi deo teksta).

 

Fukushima Nuclear Accident – a simple and accurate explanation

I am writing this text (Mar 12) to give you some peace of mind regarding some of the troubles in Japan, that is the safety of Japan’s nuclear reactors. Up front, the situation is serious, but under control. And this text is long! But you will know more about nuclear power plants after reading it than all journalists on this planet put together.

There was and will not be any significant release of radioactivity.

By “significant” I mean a level of radiation of more than what you would receive on – say – a long distance flight, or drinking a glass of beer that comes from certain areas with high levels of natural background radiation.

I have been reading every news release on the incident since the earthquake. There has not been one single (!) report that was accurate and free of errors (and part of that problem is also a weakness in the Japanese crisis communication). By “not free of errors” I do not refer to tendentious anti-nuclear journalism – that is quite normal these days. By “not free of errors” I mean blatant errors regarding physics and natural law, as well as gross misinterpretation of facts, due to an obvious lack of fundamental and basic understanding of the way nuclear reactors are build and operated. I have read a 3 page report on CNN where every single paragraph contained an error.

We will have to cover some fundamentals, before we get into what is going on.

Construction of the Fukushima nuclear power plants

The plants at Fukushima are so called Boiling Water Reactors, or BWR for short. Boiling Water Reactors are similar to a pressure cooker. The nuclear fuel heats water, the water boils and creates steam, the steam then drives turbines that create the electricity, and the steam is then cooled and condensed back to water, and the water send back to be heated by the nuclear fuel. The pressure cooker operates at about 250 °C.

The nuclear fuel is uranium oxide. Uranium oxide is a ceramic with a very high melting point of about 3000 °C. The fuel is manufactured in pellets (think little cylinders the size of Lego bricks). Those pieces are then put into a long tube made of Zircaloy with a melting point of 2200 °C, and sealed tight. The assembly is called a fuel rod. These fuel rods are then put together to form larger packages, and a number of these packages are then put into the reactor. All these packages together are referred to as “the core”. The Zircaloy casing is the first containment. It separates the radioactive fuel from the rest of the world.

The core is then placed in the “pressure vessels”. That is the pressure cooker we talked about before. The pressure vessels is the second containment. This is one sturdy piece of a pot, designed to safely contain the core for temperatures several hundred °C. That covers the scenarios where cooling can be restored at some point.

The entire “hardware” of the nuclear reactor – the pressure vessel and all pipes, pumps, coolant (water) reserves, are then encased in the third containment. The third containment is a hermetically (air tight) sealed, very thick bubble of the strongest steel.

The third containment is designed, built and tested for one single purpose: To contain, indefinitely, a complete core meltdown.

For that purpose, a large and thick concrete basin is cast under the pressure vessel (the second containment), which is filled with graphite, all inside the third containment. This is the so-called “core catcher”. If the core melts and the pressure vessel bursts (and eventually melts), it will catch the molten fuel and everything else. It is built in such a way that the nuclear fuel will be spread out, so it can cool down.

This third containment is then surrounded by the reactor building. The reactor building is an outer shell that is supposed to keep the weather out, but nothing in. (this is the part that was damaged in the explosion, but more to that later).

BWR model reaktora

Fundamentals of nuclear reactions

The uranium fuel generates heat by nuclear fission. Big uranium atoms are split into smaller atoms. That generates heat plus neutrons (one of the particles that forms an atom). When the neutron hits another uranium atom, that splits, generating more neutrons and so on. That is called the nuclear chain reaction.

Now, just packing a lot of fuel rods next to each other would quickly lead to overheating and after about 45 minutes to a melting of the fuel rods. It is worth mentioning at this point that the nuclear fuel in a reactor can *never* cause a nuclear explosion the type of a nuclear bomb. Building a nuclear bomb is actually quite difficult. In Chernobyl, the explosion was caused by excessive pressure buildup, hydrogen explosion and rupture of all containments, propelling molten core material into the environment (a “dirty bomb”). Why that did not and will not happen in Japan, further below.

In order to control the nuclear chain reaction, the reactor operators use so-called “control rods”. The control rods absorb the neutrons and kill the chain reaction instantaneously. A nuclear reactor is built in such a way, that when operating normally, you take out all the control rods. The coolant water then takes away the heat (and converts it into steam and electricity) at the same rate as the core produces it. And you have a lot of leeway around the standard operating point of 250°C.

The challenge is that after inserting the rods and stopping the chain reaction, the core still keeps producing heat. The uranium “stopped” the chain reaction. But a number of intermediate radioactive elements are created by the uranium during its fission process, most notably Cesium and Iodine isotopes, i.e. radioactive versions of these elements that will eventually split up into smaller atoms and not be radioactive anymore. Those elements keep decaying and producing heat. Because they are not regenerated any longer from the uranium (the uranium stopped decaying after the control rods were put in), they get less and less, and so the core cools down over a matter of days, until those intermediate radioactive elements are used up.

This residual heat is causing the headaches right now.

So the first “type” of radioactive material is the uranium in the fuel rods, plus the intermediate radioactive elements that the uranium splits into, also inside the fuel rod (Cesium and Iodine).

There is a second type of radioactive material created, outside the fuel rods. The big main difference up front: Those radioactive materials have a very short half-life, that means that they decay very fast and split into non-radioactive materials. By fast I mean seconds. So if these radioactive materials are released into the environment, yes, radioactivity was released, but no, it is not dangerous, at all. Why? By the time you spelled “R-A-D-I-O-N-U-C-L-I-D-E”, they will be harmless, because they will have split up into non radioactive elements. Those radioactive elements are N-16, the radioactive isotope (or version) of nitrogen (air). The others are noble gases such as Xenon. But where do they come from? When the uranium splits, it generates a neutron (see above). Most of these neutrons will hit other uranium atoms and keep the nuclear chain reaction going. But some will leave the fuel rod and hit the water molecules, or the air that is in the water. Then, a non-radioactive element can “capture” the neutron. It becomes radioactive. As described above, it will quickly (seconds) get rid again of the neutron to return to its former beautiful self.

This second “type” of radiation is very important when we talk about the radioactivity being released into the environment later on.

What happened at Fukushima

I will try to summarize the main facts. The earthquake that hit Japan was 7 times more powerful than the worst earthquake the nuclear power plant was built for (the Richter scale works logarithmically; the difference between the 8.2 that the plants were built for and the 8.9 that happened is 7 times, not 0.7). So the first hooray for Japanese engineering, everything held up.

When the earthquake hit with 8.9, the nuclear reactors all went into automatic shutdown. Within seconds after the earthquake started, the control rods had been inserted into the core and nuclear chain reaction of the uranium stopped. Now, the cooling system has to carry away the residual heat. The residual heat load is about 3% of the heat load under normal operating conditions.

The earthquake destroyed the external power supply of the nuclear reactor. That is one of the most serious accidents for a nuclear power plant, and accordingly, a “plant black out” receives a lot of attention when designing backup systems. The power is needed to keep the coolant pumps working. Since the power plant had been shut down, it cannot produce any electricity by itself any more.

Things were going well for an hour. One set of multiple sets of emergency Diesel power generators kicked in and provided the electricity that was needed. Then the Tsunami came, much bigger than people had expected when building the power plant (see above, factor 7). The tsunami took out all multiple sets of backup Diesel generators.

When designing a nuclear power plant, engineers follow a philosophy called “Defense of Depth”. That means that you first build everything to withstand the worst catastrophe you can imagine, and then design the plant in such a way that it can still handle one system failure (that you thought could never happen) after the other. A tsunami taking out all backup power in one swift strike is such a scenario. The last line of defense is putting everything into the third containment (see above), that will keep everything, whatever the mess, control rods in our out, core molten or not, inside the reactor.

When the diesel generators were gone, the reactor operators switched to emergency battery power. The batteries were designed as one of the backups to the backups, to provide power for cooling the core for 8 hours. And they did.

Within the 8 hours, another power source had to be found and connected to the power plant. The power grid was down due to the earthquake. The diesel generators were destroyed by the tsunami. So mobile diesel generators were trucked in.

This is where things started to go seriously wrong. The external power generators could not be connected to the power plant (the plugs did not fit). So after the batteries ran out, the residual heat could not be carried away any more.

At this point the plant operators begin to follow emergency procedures that are in place for a “loss of cooling event”. It is again a step along the “Depth of Defense” lines. The power to the cooling systems should never have failed completely, but it did, so they “retreat” to the next line of defense. All of this, however shocking it seems to us, is part of the day-to-day training you go through as an operator, right through to managing a core meltdown.

It was at this stage that people started to talk about core meltdown. Because at the end of the day, if cooling cannot be restored, the core will eventually melt (after hours or days), and the last line of defense, the core catcher and third containment, would come into play.

But the goal at this stage was to manage the core while it was heating up, and ensure that the first containment (the Zircaloy tubes that contains the nuclear fuel), as well as the second containment (our pressure cooker) remain intact and operational for as long as possible, to give the engineers time to fix the cooling systems.

Because cooling the core is such a big deal, the reactor has a number of cooling systems, each in multiple versions (the reactor water cleanup system, the decay heat removal, the reactor core isolating cooling, the standby liquid cooling system, and the emergency core cooling system). Which one failed when or did not fail is not clear at this point in time.

So imagine our pressure cooker on the stove, heat on low, but on. The operators use whatever cooling system capacity they have to get rid of as much heat as possible, but the pressure starts building up. The priority now is to maintain integrity of the first containment (keep temperature of the fuel rods below 2200°C), as well as the second containment, the pressure cooker.  In order to maintain integrity of the pressure cooker (the second containment), the pressure has to be released from time to time. Because the ability to do that in an emergency is so important, the reactor has 11 pressure release valves. The operators now started venting steam from time to time to control the pressure. The temperature at this stage was about 550°C.

This is when the reports about “radiation leakage” starting coming in. I believe I explained above why venting the steam is theoretically the same as releasing radiation into the environment, but why it was and is not dangerous. The radioactive nitrogen as well as the noble gases do not pose a threat to human health.

At some stage during this venting, the explosion occurred. The explosion took place outside of the third containment (our “last line of defense”), and the reactor building. Remember that the reactor building has no function in keeping the radioactivity contained. It is not entirely clear yet what has happened, but this is the likely scenario: The operators decided to vent the steam from the pressure vessel not directly into the environment, but into the space between the third containment and the reactor building (to give the radioactivity in the steam more time to subside). The problem is that at the high temperatures that the core had reached at this stage, water molecules can “disassociate” into oxygen and hydrogen – an explosive mixture. And it did explode, outside the third containment, damaging the reactor building around. It was that sort of explosion, but inside the pressure vessel (because it was badly designed and not managed properly by the operators) that lead to the explosion of Chernobyl. This was never a risk at Fukushima. The problem of hydrogen-oxygen formation is one of the biggies when you design a power plant (if you are not Soviet, that is), so the reactor is build and operated in a way it cannot happen inside the containment. It happened outside, which was not intended but a possible scenario and OK, because it did not pose a risk for the containment.

So the pressure was under control, as steam was vented. Now, if you keep boiling your pot, the problem is that the water level will keep falling and falling. The core is covered by several meters of water in order to allow for some time to pass (hours, days) before it gets exposed. Once the rods start to be exposed at the top, the exposed parts will reach the critical temperature of 2200 °C after about 45 minutes. This is when the first containment, the Zircaloy tube, would fail.

And this started to happen. The cooling could not be restored before there was some (very limited, but still) damage to the casing of some of the fuel. The nuclear material itself was still intact, but the surrounding Zircaloy shell had started melting. What happened now is that some of the byproducts of the uranium decay – radioactive Cesium and Iodine – started to mix with the steam. The big problem, uranium, was still under control, because the uranium oxide rods were good until 3000 °C. It is confirmed that a very small amount of Cesium and Iodine was measured in the steam that was released into the atmosphere.

It seems this was the “go signal” for a major plan B. The small amounts of Cesium that were measured told the operators that the first containment on one of the rods somewhere was about to give. The Plan A had been to restore one of the regular cooling systems to the core. Why that failed is unclear. One plausible explanation is that the tsunami also took away / polluted all the clean water needed for the regular cooling systems.

The water used in the cooling system is very clean, demineralized (like distilled) water. The reason to use pure water is the above mentioned activation by the neutrons from the Uranium: Pure water does not get activated much, so stays practically radioactive-free. Dirt or salt in the water will absorb the neutrons quicker, becoming more radioactive. This has no effect whatsoever on the core – it does not care what it is cooled by. But it makes life more difficult for the operators and mechanics when they have to deal with activated (i.e. slightly radioactive) water.

But Plan A had failed – cooling systems down or additional clean water unavailable – so Plan B came into effect. This is what it looks like happened:

In order to prevent a core meltdown, the operators started to use sea water to cool the core. I am not quite sure if they flooded our pressure cooker with it (the second containment), or if they flooded the third containment, immersing the pressure cooker. But that is not relevant for us.

The point is that the nuclear fuel has now been cooled down. Because the chain reaction has been stopped a long time ago, there is only very little residual heat being produced now. The large amount of cooling water that has been used is sufficient to take up that heat. Because it is a lot of water, the core does not produce sufficient heat any more to produce any significant pressure. Also, boric acid has been added to the seawater. Boric acid is “liquid control rod”. Whatever decay is still going on, the Boron will capture the neutrons and further speed up the cooling down of the core.

The plant came close to a core meltdown. Here is the worst-case scenario that was avoided: If the seawater could not have been used for treatment, the operators would have continued to vent the water steam to avoid pressure buildup. The third containment would then have been completely sealed to allow the core meltdown to happen without releasing radioactive material. After the meltdown, there would have been a waiting period for the intermediate radioactive materials to decay inside the reactor, and all radioactive particles to settle on a surface inside the containment. The cooling system would have been restored eventually, and the molten core cooled to a manageable temperature. The containment would have been cleaned up on the inside. Then a messy job of removing the molten core from the containment would have begun, packing the (now solid again) fuel bit by bit into transportation containers to be shipped to processing plants. Depending on the damage, the block of the plant would then either be repaired or dismantled.

Now, where does that leave us?

  • The plant is safe now and will stay safe.
  • Japan is looking at an INES Level 4 Accident: Nuclear accident with local consequences. That is bad for the company that owns the plant, but not for anyone else.
  • Some radiation was released when the pressure vessel was vented. All radioactive isotopes from the activated steam have gone (decayed). A very small amount of Cesium was released, as well as Iodine. If you were sitting on top of the plants’ chimney when they were venting, you should probably give up smoking to return to your former life expectancy. The Cesium and Iodine isotopes were carried out to the sea and will never be seen again.
  • There was some limited damage to the first containment. That means that some amounts of radioactive Cesium and Iodine will also be released into the cooling water, but no Uranium or other nasty stuff (the Uranium oxide does not “dissolve” in the water). There are facilities for treating the cooling water inside the third containment. The radioactive Cesium and Iodine will be removed there and eventually stored as radioactive waste in terminal storage.
  • The seawater used as cooling water will be activated to some degree. Because the control rods are fully inserted, the Uranium chain reaction is not happening. That means the “main” nuclear reaction is not happening, thus not contributing to the activation. The intermediate radioactive materials (Cesium and Iodine) are also almost gone at this stage, because the Uranium decay was stopped a long time ago. This further reduces the activation. The bottom line is that there will be some low level of activation of the seawater, which will also be removed by the treatment facilities.
  • The seawater will then be replaced over time with the “normal” cooling water
  • The reactor core will then be dismantled and transported to a processing facility, just like during a regular fuel change.
  • Fuel rods and the entire plant will be checked for potential damage. This will take about 4-5 years.
  • The safety systems on all Japanese plants will be upgraded to withstand a 9.0 earthquake and tsunami (or worse)
  • I believe the most significant problem will be a prolonged power shortage. About half of Japan’s nuclear reactors will probably have to be inspected, reducing the nation’s power generating capacity by 15%. This will probably be covered by running gas power plants that are usually only used for peak loads to cover some of the base load as well. That will increase your electricity bill, as well as lead to potential power shortages during peak demand, in Japan.

If you want to stay informed, please forget the usual media outlets and consult the following websites:

 
27 komentara

Objavljeno od strane na mart 13, 2011 in Energija, Nuklearna energija

 

27 responses to “Nuklearna kriza u Japanu: šta se zaista dešava?

  1. Miloš Vasiljević

    mart 15, 2011 at 20:31

    Odličan tekst, treba čitati na engleskom i do kraja, veoma zanimljivo.

     
  2. Srdjan

    mart 15, 2011 at 22:37

    bravo za tebe!

    bolje da si ti novinar, bar nešto saznam od tebe!

     
  3. Vojin

    mart 16, 2011 at 09:49

    Svaka čast na ideji da se postave iole relevantni tekstovi i na srpskom jeziku.
    Moram da napomenem da se autoru teksta dr Omenu se potkrala greška i da se zapravo radi o zemljotresu koji je 5 puta bio jači, a ne 7 puta od onog za koji je NE bila projektovana.
    Iako sam protivnik ideje korišćenja nuklearne energije ipak ću pre da verujem nekom objašnjenju baziranom na do sada poznatim činjenicama o događaju i odgovarajućem naučnom objašnjenju (iako ga je dao čovek koji se zalaže za nuklearnu energiju) nego naklapanju neukog novinara koji teži senzacionalizmu po svaku cenu.
    Pozdrav,

     
    • Ivan

      mart 16, 2011 at 10:14

      Hvala na komentaru, Vojine!

      Evo, da izračunamo: (10 ** 8,9) / (10 ** 8,2) = 5,01187234, toliko puta je bio jači zemljotres od projektovanog najjačeg. Međutim, kasnije je navedeno da je bio 9,0 stepeni po Rihteru…

       
  4. jovan jovanovic

    mart 16, 2011 at 13:01

    Nemam komentar, samo zelim da primam clanke i dalje.

     
  5. PCBeast

    mart 16, 2011 at 14:14

    To je zato sto su koristili AMD karte a ne nVidia.

     
  6. Nesham

    mart 16, 2011 at 14:42

    (10**9)/(10**8,2)=6,309573444801

    što je i dalje ispod 7x.

     
    • Ivan

      mart 16, 2011 at 21:03

      Slažem se, dakle, preko 6x jači zemljotres od projektovanog. Bravo za graditelje!

       
  7. quetzalcoatl

    mart 16, 2011 at 14:49

    Sjajan tekst, sjajan izvor informacija.
    Bez ‘tabloidno-novinarskih’, bombastcnih i apokalipticnih naslova.
    Lepo objasnjeno.
    Samo treba procitati, sto izgleda nase (a i strane) novinare i spikere-voditelje-prezentere na TVu mrzi.

     
    • Ivan

      mart 16, 2011 at 21:08

      Hvala na komentaru. Ideja je nastala dok sam čitao vesti na tri naša najveća informativna portala i veliki broj komentara na ovu temu. Napumpani naslovi „Japan izgubio kontrolu nad reaktorima“, „Novi Černobilj za 24h“ navode čitaoce na paniku, a s loše informisanim ljudima u panici — lako se manipuliše.

       
  8. Marko

    mart 16, 2011 at 15:07

    Ako malo bolje procitate taj clanak videcete da je to odlicno uradjen domaci zadatak sa potcenjivackim osvrtom na Rusiju i Iran, kako oni nemaju pojma. Taj domaci bi verovatno u skoli dobio dobru ocenu ali problem sa njim je ono sto je problem i sa svom teorijom a to je da ne prolazi reality check. Jednostavno ne prolazi u stvarnosti pogotovo sto je taj clanak napisan 2 dan po izbijanju krizne situacije i sva predvidjanja iz tog testa su se sada cetiri dana pokazala pogresna. Znaci situacija je eskalirala znatno van ovoga teksta a i poslednji dokaz za to je sto se radijacija pojavila u vodi za pice 50 km od reaktora. Sto je po tvorcu ovog clanka nemoguce da se desi. U sustini to je arogantni naucnicki stav jednog americkog naucnika koji je posve iskljuciv i upravo zbog takvih likova se i desavaju nesrece.

     
    • Ivan

      mart 16, 2011 at 21:37

      Dr Omen, autor teksta (polu-nemac), svakako zastupa stav i argumentuje ga, uz vrlo lep i jasan prikaz kako NE radi.

      Od 12. do 16. marta prilike su se promenile i ono što je napisao u prvoj rečenici više ne stoji, što svakako prihvatam. Vrlo mi je drago da si reagovao — znalačka i razumna debata. S obzirom da sam redigovao i skreatio izvorni tekst, potvrđujem da je bilo podsmevanja Iranu. S druge strane, najveći broj nuklearnih incidenata bio je ubedljivo najviše u Rusiji/SSSR, iako nemaju najviše reaktora.

      Kada se projektuje NE, koristi se logika „šta ako otkaže X?“, pa se da odgovor i opet postavi isto pitanje — to je tzv. „defense of depth“ koji bi trebalo da spreči „kineski sindrom„, tj. da jezgro reaktora metaforički probije put kroz središte Zemlje i stigne do Kine. Defense of depth pravi se tako da se zamisli najgori mogući scenario. Naravno, ne postoji „bulletproof“ dizajn ni plan, posebno kad uključuje ljude i prirodu. Uštede tokom izgradnje/remonta/inspekcije su ogromne ako se nedostatak sakrije ili nešto preskoči. Pronašao sam vest da iako je reaktor 1 trebalo da bude zauvek isključen ove godine, a zapravo je plan bio da mu se produži rad na još 10 godina, dok je celo postrojenje trebalo da dobije još jedan, sedmi reaktor, dok su reaktori 4, 5 i 6 trebali da povećaju izlaznu snagu (u trenutku zemljotresa bili su van pogona).

      Lično mi je najveća misterija zašto mobilne dizel pumpe nikada nisu iskorišćene (prve dizel agregate zbrisao je cunami). Svi problemi koji su kasnije nastali bili zbog regulacije hlađenja. Zapravo 90% nuklearnih problema svuda je povezano sa sistemom za hlađenje. Nisam naišao na podatak da je nađena radijacija na 50km u vodi. Kada bismo znali koliko i koja — znali bi šta se na licu mesta dešava, što ne zna tačno ni preostalih 50 radnika jer ne mogu da priđu dovoljno blizu. Dok su goreli reaktori nijednom nije bio prilike da se izme uzorak dima, jer helikopterima nije dopušteno (moguće) da se približe.

       
  9. Marko

    mart 17, 2011 at 11:54

    [6:48 a.m. ET Wednesday, 7:48 p.m. in Tokyo] Tests revealed traces of radiation in tap water in Fukushima city, 80 kilometers (50 miles) from the Daiichi nuclear plant, the local government said Wednesday …

    Sto se tice dizel agregata za pumpe tice problem je sto je cunami paralelno sa dizel pumpama unistio i celu elektroniku postrojenja na koju bi kasnije eventualno moglo da se nakaci neko externo napajanje i tako nastavi ceo proces hladjenja. Bez te elektronike i sistema upravljanja je situacija i eskalirala gde je sada i upravo zbog toga sada pribegavaju Cernobilskim metodama sa helikopterima. Sto mene oped dovodi do sledeceg pitanja. Da li to znaci da je jezgro direktno izlozeno kao u Cernobilu i da mogu da ga polivaju sa vodom i smrkovima !? Samo se nadam da nije tako i da hlade pregrejano gorivo sa nuklearnih sipki …
    U svakom slucaju i ja sam bio naisao na ovaj tekst preko twitera cim je bio objavljen i prvo sam se odusevio sa njim. Ulio mi je neki mir i sigurnost da ce sve biti OK i da nista lose ne moze da se desi. Medjutim kada su stvari pocele da se odvijaju u sasvim drugom pravcu onda sam shvatio ustvari koliko je taj tekst opasan i cemu sluzi pa i kako sam naseo. Zamisli samo sad da smo recimo negde u blizini Fukushime koliko bi mogao da nas kosta glave taj tekst a opet koliko je takvih ljudi bilo. To na dusu autoru ovog teksta. Upravo ovaj tekst govori o perfidnosti i aroganciji ljudi koji su u Nuklearnoj indistriji i koliko se bave posledicama onoga sto kazu ili urade. Naravno vec su najavili i III generaciju nekleanih reaktora koji imaju sistem hladjenja vode bez pumpi najprostije receno slobodnim tokom vode koje su naravno savrseno bezbedne …
    I dok nas oni tako zamajavaju situacija u svetu i oko nas je ovakva :

    http://www.insc.anl.gov/pwrmaps/map/world_map.php

    Niko tu nije bezbedan jer smo okruzeni Fukushimama.

     
    • Ivan

      mart 18, 2011 at 02:51

      Small, harmless amounts of iodine — a potential byproduct of a nuclear meltdown — were found in the city’s water.

      Izotop cezijuma i joda oslobođen je 12. marta prilikom namrenog ispuštanja pritiska iz reaktora 1. Oni se oslobađaju kada šipke od cirkonijuma (u kojima je gorivo) počnu da se tope u jezgru. To znači da je u jezgru temperatura premašila 2.200 stepeni C, i da pritisak nije oslobođen — sud pod pritiskom (pressure vessel) bi eksplodirao. Jod i cezujum, sa vremenom poluraspada od nekoliko sekundi, su „najbolja stvar“ od drugih (još gorih) mogućnosti.

      Ako je informacija koju si naveo tačna, da je cela elektronika za pumpe uništena, onda dovlačenje struje dalekovodima neće rešiti stvar. Link koji si dao nije moguće otvoriti, traži user/pass, probao sam admin/1234(5), ne radi😉

       
      • Marko

        mart 18, 2011 at 13:50

        Probaj, ovo bi trebalo da bude OK😉.

         
      • Ivan

        mart 18, 2011 at 22:15

        Da li je ovo raspored NE po svetu? Kako da Kanada nema ni jednu, a pre neki dan su imali incident kada se voda za hlađenje, obogaćena ko-zna-čime, izlila u jezero Ontario? Kako vidim sa slike, onda je najsigurnije da se preseliš(mo) u Aftriku, ali da prihvatimo podsaharske uslove života. I bolesti. TBC, HIV…

        Hm, hoćemo i frižider i zamrživač i bojler i par klima, računar, TV? Hm, hoćemo industriju, preradu, proizvodnju? Želimo 2 automobila po domaćinstvu, avione, železnicu? „Život dostojan čoveka“ za sve? „Nama“ treba još više, jer nas je puno, gladni smo (energije)!

        Ali želimo da budemo humani, pravedni, društveno odgovorni, ekološki osvešćeni — a da imamo sve udobnosti? Na žalost, nije moguće a da se ruke ne isprljaju.

         
    • Zoki

      mart 20, 2011 at 21:55

      http://www.insc.anl.gov/pwrmaps/map/world_map.php
      Ima li neko podatke za pristup ovom linku?

       
      • Ivan

        mart 20, 2011 at 22:19

        Nisam ja ostavio link, ali tu sliku moguće je videti ovde.

         
      • Zoki

        mart 20, 2011 at 23:10

        Zdravo Ivane,

        Pomislio sam da je nesto osbiljnije, tu slicicu sam video.

        Hvala na odgovru.

        Pozdrav

        P.S. Odlican ti je blog.

         
  10. Sanja Ob.

    mart 17, 2011 at 20:14

    Svaka cast Ivanu … hvala na obavjestenju

     
  11. Vojin

    mart 18, 2011 at 08:38

    Da se nadovežem na priču oko elektronike. Pročitao sam na netu da im se čitava elektronika nalazi ispod površine zemlje tako da je pitanje da li je od nje išta i ostalo posle onolike količine vode koja ih je zadesila. Zbog istog razloga i dovođenje prenosivih agregata nije bilo moguće zbog velike količine otpada nanetog kako cunamijem tako i potonjim eksplozijama. Ovo su naravno samo neke logičnije pretpostavke, a samo japanski inženjeri u Fukušimi znaju sa kakvim se sve logističkim košmarom susreću iz minuta u minut. Između ostalog, za raščišćavanje svog tog nanetog smeća bilo im je potrebno 6 (šest) dana, uz naravno povremene obustave radova zbog visoke radijacije. Sada kada su pročistili neke koridore unutar kompleksa i policijski vodeni topovi i vatrogasna vozila su prišla bliže objektima kojima je hlađenje najpotrebnije u ovom trenutku. A to je izgleda bazen sa „istrošenim“ gorivom kod reaktora br. 4.
    Ipak, pretpostavljam da i za ovaj problem imaju rešenje jer oni nisu nacija koja bilo šta radi stihijski i impulsivno, pa i u ovakvim kataklizmičnim okolnostima. Čak i kad je u pitanju humanitarna pomoć žele da prvo sagledaju situaciju u celosti pa da tek onda saopšte šta im je od pomoći neophodno.
    Najnovije vesti mežete pronaći na NISA-inom sajtu (Nuclear and Industrial Safety Agency, http://www.nisa.meti.go.jp/english/index.html ).

     
    • Petar

      mart 18, 2011 at 13:55

      Eeeee bogami oni meni jesu iz nekog razloga dragi i vozim japanski auto bas is tih razloga jer imam, ili sam imao, poverenja u njih.

      Razvoj situacije u zadnje vreme mi je dosta narusio osecaj da znaju sta rade. Pre mi se cini da nece da kazu a truju sebe i svet radijacijom 7 dan pa cu u buducnosti da razmislim kada budem kupovao delove za kola.

      Elem da ne bi bila samo prica evo ga i link o tome kako su zadnjih 10 godina nekoliko puta falsifikovali sigurnosne izvestaje o stanju nuklearke …

      http://www.businessweek.com/news/2011-03-18/japan-disaster-caps-decades-of-faked-reports-accidents.html

       
  12. Dragan Nikolic

    mart 18, 2011 at 20:08

    Procitao sam sve ovo ispred.Nesto mi nije jasno,Japanci sami podizu svoje nivoe opasnosti,a ja treba da verujem nekom ameru“dokazanom dusebrizniku“licno sam osetio na svojoj kozi njihovu brigu,nacin ubedjivanja,covekoljubivost,A-10[radio-aktivni oprasivac] za koji sam siguran da imate objasnjenje,{ali da naglasim ,nijedna radio-aktivnost nije opasna ako nije na vasoj kozi ili ispod}.Ne pisem ovo zlonamerno,samo me zanima sta hocete da kazete,za koga treba da navijam??? za „polunemca“?Jedno je sigurno,svaki nuklearni incident je KATASTROFA!!! Sto se nas laika tice detalji su potpuno nebitni.Princip rada,kako se hladi,“sta ako“,sve je to bedno.Toliko bedno objasnjenje da ne treba komentar.Gospodin sa Japanskim autom nece da kupuje delove za njega jer mu nije jasan rad reaktora.Da ne duzim.Ovom energijom niko nije ovladao i iskontrolisao,svako objasnjavanje je perverzno, plitko!Nego kako da pomognemo tim jadnim ljudima jer oni kod nas izdonirase prilicno?

     
  13. Dragan Nikolic

    mart 19, 2011 at 08:50

    Pozdrav Ivane! Drago mi je da si se javio.Nemam nista protiv tvog razmisljanj,imas pravo,ne sporim.Ja samo pisem ,smatram,malo sire.Bila je Ukrajina,nezelim da bude i Japan!Nego sta posle,da li je tu kraj???Treba raditi na toj tehnologiji,obavezno,ali ne treba je toliko omasoviti zarad profita onih koji vec profitiraju,globalno mi smo „gotovi“nisam pesimista,ako nas ne zakace direktno,onda nam posalju bas taj otpad,primera radi Aleksinacki rudnici,zgodno mesto,rupa!Sta rade sa Hrvatima?Skupo platise drzavu.Sta sa Bugarima,kriticni do Boga!!! A mi smo tako blizu!!!Da li ste gledali sinoc emisiju „da mozda ne“?Mi smo u potpunom mraku,i u slepoj ulici!Mnogo strunjaka,jos vise sukoba,ne bih da koristim teze reci,na momente je bilo zalosno smesno.Nagadjam ko za koga radi.Nego,neosporna cinjenica je da se previse krije. Voleo bih da mi na ono predhodno odgovoris na meil,zamolio bih te.Zanima me tvoje misljenje.Nadam se da ce ovo hladjenje imati efekta,iskreno se nadam.Samo da pocnu da hlade sve reaktore. Pozdrav znas da je kod mene ABH centar

     
  14. Darko

    mart 21, 2011 at 16:14

    Lepo je to gospodin objasnio.
    Meni je nukleana fizika delom profesija. MSc Medical Imaging. Ukratko iz onog sto ja znam i sto sam video na snimcima, iznosim misljenje:
    1. Ili je raktor ugasen sam od sebe bez ikakvih problema, a svi problemi da su zbog bazena sa istrosenim sipkama gore na krovu. Inac ono prskanje vode odozgo je cirkusarija (uzevsi u obzir profesorovu verziju)

    2. jezgro se iztopilo i oni su samo kupovali vreme cekajuci da preser vesel dodje na max pritisak i onda ga oslobadjali pritiska. sto dodje kao da te bokser udari sakom u glavu (crnobil) a ovo (fukosima) je 25 laganih samarcica. i naravno sve je puno lakse jer u medjuvremenu jezgro se hladi i problem se smanjuje.

     
    • Ivan

      mart 21, 2011 at 22:01

      Bojim se da je odgovor pod 2).

      Imajući ovu vrlo lošu sliku, koju vidim kao „zaustavljenu“ na ivici ponora, gde su stroncijum i argon? Uranijum i plutonijum? Kako se detektuju „samo“ nestabilni izotopi cezijuma i joda? I to u realtivno malim količinama?

       
  15. GetYourShhhTogether

    mart 11, 2014 at 15:00

    whoah this blog is magnificent i love studying your articles.

    Keep up the great work! You recognize, many people are looking round for this
    info, you can aid them greatly.

     

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