Nuklearna tehnologija, samo mirnodopska molim!

[hazard]

Prvi fuzioni reaktor se ocekuje za 30 godina evo poslednjih 50 godina :) ako ga ikada bude, ja se kladim da ce to biti negde 2100. godine. Taman da uz vece koriscenje obnovljivih izvora i fuzije izmuzemo fosilna goriva do kraja.Sto se tice hemijskih raketa, kazem ja tipujem da ce u buducnosti verovatno biti jeftinije od ovih 150k, jer kao sto rekoh, to je cena koja pokriva inicijalnu investiciju (koja ce kad-tad valjda biti povracena) + fiksne troskove (dakle ne gorivo i stvari po letu nego "overhead") koji ce se spustiti ukoliko bude vise interesovanje i vise polazaka, ako se izgradi jos neka letelica (ili mozda 2-3) i tako dalje. Sad ja ne znam njihovom strukturu troskova tako da mi ostaje da nagadjam da li ce cena pasti 5%, 10%, 20% ili vise. A mozda i neko nadje jeftiniji nacin do orbite do moje penzije :)

[bigvlada]

bilo je više projekata reaktora jer postoji više konkurentnih tehnologija. Međutim, ovo što se sada gradi u Francuskoj je prototip ne reaktora već cele elektrane. Cena je takva da moraju da učestvuju praktično sve države sa razvijenom industrijom. Mnogo veći projekat od dosadašnjih manje više laboratorijskih ili ograničenih na jedan naučni institut. Verujem da će 2040 ta elektrana označiti prekretnicu kao što je to učinila ona na Nijagarinim vodopadima. Lavovski deo troškova čine gorivo i telo rakete. Skupo je proizvoditi i skladištiti tečno gorivo dok čvrsto ima mnogo lošije karakteristike. 90% gvožđurije se odbacuje posle par minuta leta. I za šatl su pričali da će drastično sniziti troškove, da će leteti svake nedelje itd... U USA je više godina vladao moratorijum na klasične rakete (do katastrofe Čelendžera) jer su mislili da će šatl zameniti sve. Postojao je jedan projekat (mislim da sam ga pominjao, nemački OTRAG http://en.wikipedia.org/wiki/OTRAG) koji je išao tom minimalističkom logikom, ali su kod njega rizici katastrofalnog otkaza suviše veliki za bilo šta sem transporta vode i vazduha. Sertifikacija raketa za transport ljudi je dug i skup proces. Jedini, ali jedini način da transport robe u nisku orbitu ili na drugu stranu planete bude jeftiniji korišćenjem hemijskih raketa je da se revitalizuje neki od SSTO (single stage to orbit) projekata poput Chrysler serv-a, rhombus-a ili Ithacus-a. Čak i tada, treba ti letelica koja je za višekratnu upotrebu a kojoj je potrebno minimalno održavanje i broj tehničara koji bi je spremili za let. Šatl je po tom pitanju bio rupa bez dna. Ne bi me čudilo da zaključe da umesto metala, za oplatu bude morao da se koristi materijal zasnovan na ugljeniku 60 koji se i dalje proizvodi u količinama od par grama godišnje. Pre ćemo imati fuzioni reaktor na klasičnom avionu nego hmm, dijamantski avion sa hemijskim raketama.Realnije je da će budući nadzvučni putnički avioni imati kombinaciju ramjet/scramjet mlaznog motora i airbreathing raketnog motora,pokrivajuči tako brzine od 300km/h pa do preko 25 maha, sve u jednom kućištu. Razvoj takvog nečeg je stravično skup i vremenski dugačak. U poslednjem postu na temi o kosmosu imaš članak o jednom takvom motoru. Interesantno je da su kao i u slučaju Frenka Vitla, inženjeri iz UK. Iskreno želim da i ovaj motor ima bar tako lepu budućnost kao i onaj iz dvadesetih godina prošlog veka.

[bigvlada]

Iako su ovde pomenuti i nuklearni vozovi i automobili, akcenat je bačen na letelice.http://www.darkroastedblend.com/2011/05/nuclear-everything.htmlPočetkom šezdesetih je razvijen jednostavan ramjet nuklearni motor, u okviru projekta Pluton. http://www.merkle.com/pluto/pluto.htmlFast forward do 2065 i imate fuzioni motor koji radi na istom jednostavnom principu ali bez radioaktivnog otpada. Tehnologija veoma slična onoj koju je Robert Busard predvideo za buduće međuplanetarne letelice (http://en.wikipedia.org/wiki/Bussard_ramjet)

[Zaz_pi]

Ha, trazeci temu o tramvajima naletih na ovo. Steta sto se ne diskutuje na njoj. Nazalost, Amerikanci izgleda ne zele da finansiraju dalje projekat ITER(International Thermonuclear Experimental Reactor) koji treba da bude fuzioni reaktor koji se pravi u Francuskoj(uz finansijsku i naucno-tehnolosku podrsku: EU, Rusije, SAD, Kine, J. Koreje, Japana i Indije). Osnova ITERa je Tokamak(тороидальная камера с магнитными катушками), sovjetski naucnici(Nobelovci) su ga izmislili tokom '50ih, u pitanju su Igor Tam i veliki disident Andrej Saharov.

Nazalost, projekat ITER probija dobrano gornju granicu finansiranja i odredjene rokove. Ali, ako su Amerikanci mogli da utrose stotine milijardi $ za F-35, koji je debelo probio vreme ulaska u upotrebu, sa veoma sumnjivim rezultatima, mogu valjda da izdrze i nesto sto nam moze resiti sve energetske probleme.

Verujem da dosta ljudi zna da energija koja dolazi sa sunca nastaje u fuziji.

Sa druge strane, mnogo zapadnih zemalja uvodi moratorijume na nuklearnu energiju(fisija) ali zato Rusija i Kina nemaju tu nameru. Rosatom planira da uskoro izbaci novu generaciju reaktora-sigurnih i efikasnih.

 

Russian nuclear agency Rosatom plans fast reactors

Rosatom is to build a fast neutron reactor that it hopes will lead to a new wave of clean and commercially viable power stations.

Russia is attempting to eliminate nuclear waste through an unprecedented international partnership based on fast-reactor technology, which has the potential to win 10 to 15pc of the world's £150bn nuclear energy market in the near future.

At the Central European Nuclear Industry Forum (Atomex) in Prague in October, Russia’s Rosatom nuclear agency signed a deal to build a fast-neutron nuclear reactor on Russian territory in co-operation with 13 Czech companies. It is called the SVBR-100 project.

Advantages of fast-reactor technology

Like all nuclear plants, fast-reactor plants to not emit carbon dioxide. But conventional plants produce huge amounts of spent and irradiated fuel that has to be accumulated, stored and monitored as hazardous nuclear waste. This poses a radiological threat for thousands of years. The problem of what to do with it is a major headache for any country that uses atomic energy.

The main advantage of fast-neutron reactor technology over traditional nuclear power plants is that it can utilise this waste product – irradiated or highly-enriched nuclear fuel – in the process of generating energy. Fast reactors also produce far less new nuclear waste than conventional reactors, while some reactors, called fast-breeder reactors, can be used to produce an excess of plutonium, which can then be used in nuclear weapons or recycled to fuel the plant.

According to Leonid Bolshov, professor at the Institute for the Safe Development of Nuclear Energy of the Russian Academy of Sciences, the development of fast nuclear reactors is essential to close the nuclear fuel cycle.“Fast reactors will help us solve one of the most pressing problems connected with atomic energy, and that is what to do with the atomic waste from nuclear power stations that are currently operational.”

In Britain, the Nuclear Decommissioning Authority is considering plans to build two fast reactors at Sellafield in Cumbria to deal with the 120-ton plutonium waste problem there – the world’s largest stock of civilian plutonium. A feasibility study has already been submitted for building the plants, which, if given the go-ahead, could eradicate the British plutonium stockpile by around 2030. This would also have the benefit of generating electricity in the process.

All of the fast reactors tested in the world so far have been experimental models; Russia, the United States and France have considerable experience building and working with experimental fast-neutron reactors.

Russia’s BN-600 reactor, which was operational from 1980 until 2005 in the Ural Mountains, was the most advanced testing ground for the technology. It is now being replaced with the nearby BN-800 reactor, which is close to completion and is based on more advanced development of the same technology.

Powerful sodium unit produces little waste

The BN-600 reactor holds the world record for safely operating fast nuclear reactors that use sodium. It was also the world’s most powerful fast nuclear reactor with a sodium coolant; sodium in a fast reactor does not dissolve amid high levels of radiation. Thus the sodium coolant

does not require regular drainage and removal of the dissolved absorber while being refuelled.

Sodium also connects with radioactive iodine during non-volatile chemical reactions, which basically prevents its release from a normal power plant through ventilation systems. Consequently, the reactor produces a small amount of nuclear waste, which has a relatively minor effect on the surrounding environment when compared to the effects of waste produced by traditional reactors.

In 2004, the developer Fedor Mitenkov was awarded the international Global Energy Award for his contribution to fast reactors with the BN-600 project.

The technology has been so successful that Rosatom subsidiary OKBM Afrikantov led the construction consortium for the China Experimental Fast Reactor outside Beijing, which went into operation in July 2011.

During a recent visit to China by Vladimir Putin, Rosatom head Sergei Kiriyenko announced active discussions with Chinese partners on the construction of a fully functional (non-experimental) fast reactor in China, similar to the one being constructed in Russia, by Rosatom in the near future.

Prof Bolshov is very excited about the potential of the planned new fast reactor: “We have learnt a great deal from our experience with the BN-600. Russian nuclear scientists spent years perfecting the design of the reactor, and have learnt how to use sodium as a coolant.

“If, after all the discussions and licensing is taken care of, the next project is given the green light, then it has the potential to become the first commercially viable high-powered fast-neutron reactor in the world,” he says.

The coming years

Research and design work on the SVBR-100 reactor will continue until the end of 2014, while operations proper are set to begin in 2017. Potentially, it could take 10 to 15pc of the global nuclear energy market for small and medium-sized power stations. “Fast reactors are the basis of our [global] competitiveness,” says Mr Kiriyenko.

“These include the fast-neutron reactors that already exist at Beloyarsk, lead-bismuthic reactors, lead reactors and other liquid metal coolants. All of these technologies will allow us to utilise the U-238 [highly enriched] isotope in the fuel cycle, which is abundantly available in nature but is currently almost unused.”

According to Mr Kiriyenko, the United States is a key partner for developing new types of reactors for the company. “We can conduct joint R&D to develop a new generation of nuclear reactors; such co-operation should go on between our two countries on a national level and not be restricted to just one company,” he said.

Chain reaction was key find

The history of bringing fast neutrons under control can be traced back to the Italian physicist Enrico Fermi who, in 1939, speculated that fast neutrons are released during the uranium fission process.

He suggested that if the number of neutrons emitted exceeded the number of neutrons absorbed, then a chain reaction could begin. Experiments proved this theory to be correct.

The first serious attempts to develop fast-reactor technology were made in the US with the Clinch River Breeder Reactor in 1970, which was closed in 1983. The Soviet Union developed fast-reactor technology as early as the Fifties, successfully testing a number of prototypes until the sodium-cooled BN-600 FBR went into operation at Beloyarsk in April 1980.

Russia continues to develop its nuclear reactor technology, with the BN-800 and BN-1200 models currently under construction. The ultimate goal is to produce a commercially successful fast reactor.

[bigvlada]

Nove tehnologije reaktora. 

 

 

 

 

 

 

Moram da priznam da je ovaj turski primer jako interesantan. Kompanija obezbeđuje elektranu, finansiranje, obuku, nuklearno gorivo i njegovo naknadno uklanjanje. Ranije sam se protivo gradnji nuklearki u Srbiji baš zbog problema nuklearnog otpada. Želim da vidim više kompanija koje nude ovako nešto. 

[Indy]

Hvala, bigvlado.

 

Ima isti tekst ovde: http://pulitzercenter.org/reporting/asia-europe-russia-empire-nuclear-power-reactor-generator-expo-sale-kremlin

 

Mislim da je laksi za citanje od image fajlova iznad.

[Skyhighatrist]

Mislim da je laksi za citanje od image fajlova iznad.

 

Ou jea, tenks, oslijepeh

[Indy]

Sve, sve... ali, Miss Atom :0.6:

 

[Lord Protector]

misica, atom, fisija   ^_^

Edited November 22, 2014 by slow

[bigvlada]

When you wish upon a star: nuclear fusion and the promise of a brighter tomorrow
Decades in the making, Iter, a huge experimental nuclear fusion reactor in rural France, could be the site of breakthroughs that will provide limitless, clean energy and secure the planet’s future

 

The construction site at Saint-Paul-lez-Durance: when the reactor building is complete, it will rise some 60 metres into the air and reach 10 metres below the ground.

Alok Jha

Sunday 25 January 2015 10.00 GMT


The countryside of Saint-Paul-lez-Durance in Provence is a serene terrain of thickly wooded hills. On chilly January mornings, the air becomes thick with mist and the sky glows red as the sun pokes up above the horizon at dawn. By mid-morning, that haze is usually gone, leaving behind a bright blue sky with only the faintest wisp of high-altitude cloud.

As picture-postcard scenes go, it is as rural and peaceful as it gets. But incongruously nestled among these hills and vineyards, the most sophisticated, expensive machine ever built is slowly taking shape at the local Cadarache nuclear facility. It is a scientific collaboration on a worldwide scale, meant to tackle one of the biggest challenges of the 21st century – with the human population growing every year, how do we continue to make ever more electricity past 2050 (the date that the EU has set for full decarbonisation of power generation) without destroying the environment? The scientists and engineers in Saint-Paul-lez-Durance think the solution is nuclear fusion – they want to recreate a star in a box on Earth.

Everything about the project, known as Iter (formerly known as the International Thermonuclear Experimental Reactor), is huge. The main fusion reactor will be built on a flattened area of concrete that has been blasted into the hills at Cadarache and stretches to 60 football pitches. Around 2.5m cubic metres of earth and rubble were excavated from what was originally a small valley that undulated by several hundred metres in parts. That concrete baseplate sits on dozens of pillars containing layers of rubber sandwiched between the mortar and cement – not only do these pillars raise the building above the height of the surrounding countryside (the height was calculated to be above the maximum height that water would flow past if the nearby dam broke), they also create a “seismic isolation pit” that will protect the building from earthquakes.

At the centre of the concrete box where the main building will go, you can already see a circle of steel bars that trace the shape of what will become the ring-shaped vacuum vessel, where the fusion reactions will take place. Ready to haul in the huge components over the coming years, four giant cranes are rooted into the site, one of them within the circle itself. When the main building containing the reactor is complete, it will rise 60 metres into the air and reach 10 metres below the ground.

When the million or so pieces that make up the Iter machine have been delivered to site and are finally bolted and welded together, the whole thing will weigh around 23,000 tonnes, three times the weight of the Eiffel tower. The entire reactor complex – including the foundations and buildings that will sit in the seismic isolation pit – will weigh 400,000 tonnes, more than the weight of the Empire State Building.

Visiting the Iter site, I meet Steven Cowley, who has been working on the theoretical physics of nuclear fusion for three decades and is now chief executive of the UK Atomic Energy Authority (UKAEA). The last time he saw the site, there was still mud at the bottom of the main pit. Standing over the recently finished concrete platform, he gestures to where the super-hot plasma will one day start burning and fusing atoms. “It’s not ordinary by any stretch of the imagination and when it’s working, you know, it will be one of the great wonders of the world.”

Cowley has been waiting for Iter his whole career. His commitment to it is not just driven by a desire to answer scientific questions that have occupied his mind for so many decades, though. “We don’t know where we are going to get our energy from in the second half of this century, and if we don’t get fusion working we are going to be really stuck,” he says. “We have to make [iter] work. It’s not just because I work in it that I think that: it has to work and all this effort of thousands of people all the way round the world is to make sure that in 2100 you can flick a switch on the wall and have electricity.”

 

The vacuum vessel and superconducting magnets are enclosed by an enormous cold box that provides a vacuum environment cooled to -269C. This hermetically sealed ‘doughnut’ allows the plasma particles to travel without touching the sides.Lasers, x-rays, neutron cameras and radiation bolometers are used to control, evaluate and optimise the plasma. The magnet system controls, confines and shapes the plasma inside the vacuum vessel.The diverter’s purpose is to extract heat and helium ash and other impurities from the plasma. Photograph: Iter

Nuclear fusion is different from the more familiar nuclear fission, which involves splitting heavy atoms of uranium to release energy and which is at the heart of all nuclear power stations. The promise of fusion, if scientists can get it to work, is huge – unlimited power without any carbon emissions and very little radioactive waste.

The process goes on at the core of every star and the idea that mimicking it could become a source of power on Earth has been around since the years after the second world war. But for many decades fusion has seemed out of reach, requiring materials and an understanding of the chaotic behaviour of hot plasmas that was beyond the technology of the time. However, decades of smaller experiments have led to Iter, the giant project in which fusion scientists have their best possible chance to finally show that this technology could work.

Iter has its roots in a summit between Ronald Reagan and Mikhail Gorbachev towards the end of the cold war, in 1985. They agreed on very little but, almost as an afterthought, they mentioned developing fusion as a new source of energy that could benefit all mankind. Europe and Japan joined the Americans and Russians on the tentative project soon after it was conceived and, today, it also includes China, India and South Korea – in total there are 35 countries involved.

Its design is centred on heating a cloud of hydrogen gas to 10 times hotter than the core of the sun, some 150m degrees celsius, inside a ring-shaped container called a tokamak, which has superconducting magnets fixed around it like hoops fitted on a circular curtain rail. These magnets create an overlapping set of fields that keep the electrically charged gas inside from touching the sides of the tokamak and therefore losing energy.

Building a working tokamak is not straightforward. “The plasma is a bit like a lump of jelly and you are holding it with a magnetic field which is a bit like knitting wool – and imagine holding a lump of jelly with a few pieces of knitting,” says Cowley. The magnets have to be strong and Iter’s design uses superconducting magnets that only work at -269C.

Since the earliest designs, several generations of tokamak-based nuclear fusion reactors have proved that it is possible to build and run the technology at increasingly large sizes. The biggest of these is the Joint European Torus (Jet), based at Culham in Oxfordshire and run by the UKAEA. In the early 1990s, experiments there showed it was possible to fuse hydrogen and then release the resulting energy in a controlled way.

But it took more energy to fuse atoms at Jet than the scientists got back out at the end – which is useless if you want to use the technology to build a power plant. Iter’s primary goal is to fix that problem by creating what they call a “burning” plasma, something that keeps going without the need for external heating, in the same way that a log fire keeps burning after it has initially been set alight by a match. Its design is a scaled-up version of Jet and the scientists here want to produce 500 megawatts of power, 10 times its predicted input.

But scientific challenges are not the only complexities with a mega-project such as Iter. With so many countries involved, so much money and so many engineering contracts, the path to laying even the first building block of this experimental reactor has been far from smooth.

The seven partners agreed on Cadarache in 2004 and they signed an agreement two years later, which costed the project at an estimated €5bn to build and a similar amount to run for its 20-year lifetime. The agreement stated that, as hosts for the project, Europe pays 45% of the total cost while the remaining partners split the bill for the rest between them. Countries do not pay funds directly to Iter but rather provide the equivalent value in parts and services to the reactor project. The ratios are important – they were to remain in place even if the cost rose. Which it did: after a design review in 2008 that incorporated several advances in fusion science into the basic design and also took into account the increased cost of steel and concrete, the construction budget rose to €15bn.

When the Iter agreement was signed in 2006, the reactor was supposed to begin operations in 2016. With the subsequent redesign and construction delays, the current timetable does not involve a switch-on until 2020 and there will not be a working plasma in the tokamak before around 2022. The all-important fusion reactions are not likely to occur before 2027, more than 20 years after building started.



Iter will need 100,000km of superconducting wire for its magnets – enough to wrap around the equator twice.

Iter’s director general, the Japanese plasma physicist Osamu Motojima, has been in charge since 2010 and is now in the final months of his tenure. His team came under criticism in 2013 in an assessment carried out by independent consultants, who said the project’s management was inflexible and top-heavy. Motojima says that managing a project to develop a radically new technology with so many political partners was a new experience for the world, and required a “new standard of collaborative culture”. The cost increases, he added, were mainly the result of inflation from the original estimate in 2001 and also the increase in cost of basic building materials. “In general, cost is increasing but that is, I believe, within acceptable levels for stakeholders and the public.” Iter’s governing council has since accepted the thrust of the findings of the assessment report and promised change in how the project is organised, in a bid to keep it on track.

Some of the higher costs are perhaps inevitable when you are building new technologies from scratch. In Iter’s case, this is exacerbated by the partners’ wish to build the components of the reactor in facilities all over the world.

The task of making the million or so parts of Iter has been distributed among the seven partners. Iter will need 100,000km of superconducting wire for its magnets, for example – enough to wrap around the equator twice – which will be made in China, Japan, Russia, South Korea and the US. The magnets are being built in pieces in France and also China. The vacuum chamber, which will contain the hot hydrogen gas, will come in pieces from South Korea and also parts of Europe.

Getting all of this to the site in Cadarache is a huge logistical challenge. The giant magnets and vacuum chambers will begin arriving this month along a specially designated 104km road from the nearest Mediterranean port, known as the Iter Itinerary. The pieces will be enormous – the 18 D-shaped coils of wire that will make the main magnets each weigh 360 tonnes, approximately the same as a fully loaded jumbo jet. The heaviest component will weigh 900 tonnes including its transport vehicle and some will be more than 30m long; the tallest will rise four storeys from the road.

Part of this distribution of labour is to do with bringing jobs, money and prestige into hi-tech industries within the partner nations. But also, these countries will need their own expertise in building and running fusion power plants if Iter is successful and this form of power takes off.

Alok Jha at the Cadarache nuclear facility in Provence where Iter, the most sophisticated, expensive machine ever to be built, is slowly taking shape. Photograph: Gabrielle Lawrence/ITV News

Iter’s job is to show that fusion can be achieved and controlled for sustained periods in the tokamak design. It will not be a power station itself: that is the job of the next generation of fusion reactors, which will be built by countries individually with knowledge gained from the Iter experiments and which are collectively known as “DEMO” projects. China has already started planning the precursor to its DEMO project, a test device called China Fusion Engineering Test Reactor. Construction could start by 2020 and the test plant could be in operation by the mid-2030s, ready to move on to building the first fusion power plants a decade or so after that. Plans to build DEMO power plants are at an earlier stage in Japan and South Korea. There are many hurdles to get over between Iter and a commercial power plant – engineers need to come up with new materials for the walls of the vacuum vessels and the shielding around the plasma, for example. The high-grade steel being used in Iter is good enough to deal with the plasma and the radiation from the relatively small amounts of power (500MW) that will be produced there for a few minutes at a time, but commercial power plants will need much hardier materials in order to deal with the result of a plasma producing three or four times that much power, day in, day out. If all the technical and design refinements in successive experimental reactors go to plan, it is expected that the very first fusion power plants could be producing electricity for the grid by 2045-2050.

It has always been a dark joke about nuclear fusion that a commercial power station is 30 years away and that it always will be. But Iter, despite its delays and cost overruns, might finally tip the balance. It’s hard not to be hopeful that, because of the experiment under way in Cadarache, a commercial fusion reactor really is only 30 years off.

Indeed, if Iter gets its plasma working and scientists can extract more energy from the burn than they had to put in, it will change the world, says Cowley. “When this machine works I will be here, you know. The end of my career is going to be watching this machine do a fusion burn,” he says. “There are probably, over history, a handful of historic moments where in a flash the future changed. In a flash the future will change with this machine… What this is going to show is that man can make a star.”
Fusion facts: how to re-create a star on Earth

At the centre of our sun, the nuclei of hydrogen atoms (which are bare protons) are being jostled around under unimaginable pressures. Once in a while, two of them will overcome their mutual repulsion and fuse to form a nucleus of helium, releasing a little energy in the process.

It is not a straightforward process, however. Such is the repulsive force between protons that it takes millions of years to fuse two of them, even in the intense conditions within a star. Fusing bare hydrogen is therefore out of the question if you want a power station to mimic the process on Earth, so physicists tend to use two of its isotopes instead, deuterium and tritium, which are heavier versions of hydrogen that contain one and two extra neutrons in their nuclei respectively. Deuterium is abundant in seawater – around one in every 6,000 molecules contains it – and tritium can be made by the fusion reactor itself. By heating the deuterium-tritium mixture to hundreds of millions of degrees celsius inside a ring-shaped vessel, the two elements fuse to form helium, energy and fast-moving neutrons. The neutrons will be absorbed by shielding around the reactor vessel that contains lithium, and this interaction will create more tritium.

There is a virtually limitless source of fuel in the world’s oceans to feed future nuclear fusion reactors. And though there are some radioactive waste products that come from the process, they all have short half-lives and will become inert within a few hundred years, as opposed to the thousands of years for which waste from fission reactors stays dangerous.

Further, fusion power plants cannot go critical, produce runaway reactions or a meltdown in the way people sometimes worry about with nuclear fission. Like an internal combustion engine, fusion reactors will only burn the fuel put into them. And you only need a very small amount of fuel for each fusion burn in a large power station – tenths of a gram of the mixture will fill up the reactor – since the deuterium-tritium mixture is a million times more energy-dense than petrol.

 

Alok Jha is science correspondent for ITV News. You can see his visit to Iter as part of On Assignment, ITV, 27 January at 10.40pm

 

http://www.theguardian.com/science/2015/jan/25/iter-nuclear-fusion-cadarache-international-thermonuclear-experimental-reactor-steven-cowley

[bigvlada]

Ovo jeste vojni projekat, ali nema vojnu namenu. Bila je ranije priča o sličnom projektu sa početka šezdesetih, koji je koristio gusenice. Mada me i dalje zanima u koje svrhe se u nekoj pustopoljini koristi nuklearni reaktor? Napajanje gradilišta?

 

 

 

http://defence-blog.com/news/russian-army-to-build-mobile-nuclear-stations.html 

[bigvlada]

A sada nešto potpuno drugačije, torijum, izdanje za 2016. godinu.

 

 

 

I meni omiljena varijanta, podkritični reaktor. 

 

https://en.wikipedia.org/wiki/Subcritical_reactor

 

https://en.wikipedia.org/wiki/Energy_amplifier

 

Štos je u tome da se koristi akcelerator čestica kako bi otpočela nuklearna reakcija. Kada se snop prekine, prestaje i reakcija (reaktor ipak treba da se ohladi ali to nije toliko strašno jer su radne temperature u opsegu 500 - 700C). Za razliku od jednocifrenog stepena iskorišćenosti uranijuma, torijum se može iskoristiti gotovo stoprocentno. Dodatni plus je što se u torijumskim reaktoprima može iskoristiti i postojeći dugoživeći nuklearni otpad. Jedan od prvih koji je to predložio je italijanski fizičar Karlo Rubia, njegov patent na temu je otkupila jedna norveška naftna kompanija koja želi da gradi torijumske reaktore. 

 

Postoji organizacija koja se bavi promocijom ove vrste reaktora, iThec, ovo je kratak rezime prednosti u odnosu na klasične uranijumske i plutonijumske reaktore. 

 

http://ithec.org/en/technologie/

 

Znai li neko, bavi li se Vinča bilo čime sličnim, u teorijskim okvirima? Znam da imamo moratorijum na nuklearne reaktore ali ovo je drugo. Jedna tona torijuma menja 2.500.000 tona uglja (u kome opet ima 14 tona torijuma) a ima ga i u planinama pepela koje sada samo taložimo. 

Edited May 27, 2016 by bigvlada

[bigvlada]

 

 

The Thing About Thorium: Why The Better Nuclear Fuel May Not Get A Chance

 

Marin Katusa, Contributor

 

 

 

The Fukushima disaster reminded us all of the dangers inherent in uranium-fueled nuclear reactors. Fresh news this month about Tepco’s continued struggle to contain and cool the fuel rods highlights just how energetic uranium fission reactions are and how challenging to control. Of course, that level of energy is exactly why we use nuclear energy – it is incredibly efficient as a source of power, and it creates very few emissions and carries a laudable safety record to boot.

 

This conversation – “nuclear good but uranium dangerous” – regularly leads to a very good question: what about thorium? Thorium sits two spots left of uranium on the periodic table, in the same row or series. Elements in the same series share characteristics. With uranium and thorium, the key similarity is that both can absorb neutrons and transmute into fissile elements.

 

That means thorium could be used to fuel nuclear reactors, just like uranium. And as proponents of the underdog fuel will happily tell you, thorium is more abundant in nature than uranium, is not fissile on its own (which means reactions can be stopped when necessary), produces waste products that are less radioactive, and generates more energy per ton.

 

So why on earth are we using uranium? As you may recall, research into the mechanization of nuclear reactions was initially driven not by the desire to make energy, but by the desire to make bombs. The $2 billion Manhattan Project that produced the atomic bomb sparked a worldwide surge in nuclear research, most of it funded by governments embroiled in the Cold War. And here we come to it: Thorium reactors do not produce plutonium, which is what you need to make a nuke.

 

How ironic. The fact that thorium reactors could not produce fuel for nuclear weapons meant the better reactor fuel got short shrift, yet today we would love to be able to clearly differentiate a country’s nuclear reactors from its weapons program.

 

In the post-Cold War world, is there any hope for thorium? Perhaps, but don’t run to your broker just yet.

 

 

 

The Uranium Reactor

 

The typical nuclear-fuel cycle starts with refined uranium ore, which is mostly U238 but contains 3% to 5% U235. Most naturally occurring uranium is U238, but this common isotope does not undergo fission – which is the process whereby the nucleus splits and releases tremendous amounts of energy. By contrast, the less-prevalent U235 is fissile. As such, to make reactor fuel we have to expend considerable energy enriching yellowcake, to boost its proportion of U235.

 

Once in the reactor, U235 starts splitting and releasing high-energy neutrons. The U238 does not just sit idly by, however; it transmutes into other fissile elements. When an atom of U238 absorbs a neutron, it transmutes into short-lived U239, which rapidly decays into neptunium-239 and then into plutonium-239, that lovely, weaponizable byproduct.

 

When the U235 content burns down to 0.3%, the fuel is spent, but it contains some very radioactive isotopes of americium, technetium, and iodine, as well as plutonium. This waste fuel is highly radioactive and the culprits – these high-mass isotopes – have half-lives of many thousands of years. As such, the waste has to be housed for up to 10,000 years, cloistered from the environment and from anyone who might want to get at the plutonium for nefarious reasons.

 

 

 

The Thing about Thorium

 

Thorium’s advantages start from the moment it is mined and purified, in that all but a trace of naturally occurring thorium is Th232, the isotope useful in nuclear reactors. That’s a heck of a lot better than the 3% to 5% of uranium that comes in the form we need.

 

Then there’s the safety side of thorium reactions. Unlike U235, thorium is not fissile. That means no matter how many thorium nuclei you pack together, they will not on their own start splitting apart and exploding. If you want to make thorium nuclei split apart, though, it’s easy: you simply start throwing neutrons at them. Then, when you need the reaction to stop, simply turn off the source of neutrons and the whole process shuts down, simple as pie.

 

Here’s how it works. When Th232 absorbs a neutron it becomes Th233, which is unstable and decays into protactinium-233 and then into U233. That’s the same uranium isotope we use in reactors now as a nuclear fuel, the one that is fissile all on its own. Thankfully, it is also relatively long lived, which means at this point in the cycle the irradiated fuel can be unloaded from the reactor and the U233 separated from the remaining thorium. The uranium is then fed into another reactor all on its own, to generate energy.

 

The U233 does its thing, splitting apart and releasing high-energy neutrons. But there isn’t a pile of U238 sitting by. Remember, with uranium reactors it’s the U238, turned into U239 by absorbing some of those high-flying neutrons, that produces all the highly radioactive waste products. With thorium, the U233 is isolated and the result is far fewer highly radioactive, long-lived byproducts. Thorium nuclear waste only stays radioactive for 500 years, instead of 10,000, and there is 1,000 to 10,000 times less of it to start with.

 

 

 

The Thorium Leaders

 

Researchers have studied thorium-based fuel cycles for 50 years, but India leads the pack when it comes to commercialization. As home to a quarter of the world’s known thorium reserves and notably lacking in uranium resources, it’s no surprise that India envisions meeting 30% of its electricity demand through thorium-based reactors by 2050.

 

In 2002, India’s nuclear regulatory agency issued approval to start construction of a 500-megawatts electric prototype fast breeder reactor, which should be completed this year. In the next decade, construction will begin on six more of these fast breeder reactors, which “breed” U233 and plutonium from thorium and uranium.

 

Design work is also largely complete for India’s first Advanced Heavy Water Reactor (AHWR), which will involve a reactor fueled primarily by thorium that has gone through a series of tests in full-scale replica. The biggest holdup at present is finding a suitable location for the plant, which will generate 300 MW of electricity. Indian officials say they are aiming to have the plant operational by the end of the decade.

 

China is the other nation with a firm commitment to develop thorium power. In early 2011, China’s Academy of Sciences launched a major research and development program on Liquid Fluoride Thorium Reactor (LFTR) technology, which utilizes U233 that has been bred in a liquid thorium salt blanket. This molten salt blanket becomes less dense as temperatures rise, slowing the reaction down in a sort of built-in safety catch. This kind of thorium reactor gets the most attention in the thorium world; China’s research program is in a race with similar though smaller programs in Japan, Russia, France, and the U.S.

 

There are at least seven types of reactors that can use thorium as a nuclear fuel, five of which have entered into operation at some point. Several were abandoned not for technical reasons but because of a lack of interest or research funding (blame the Cold War again). So proven designs for thorium-based reactors exist and need but for some support.

 

Well, maybe quite a bit of support. One of the biggest challenges in developing a thorium reactor is finding a way to fabricate the fuel economically. Making thorium dioxide is expensive, in part because its melting point is the highest of all oxides, at 3,300° C. The options for generating the barrage of neutrons needed to kick-start the reaction regularly come down to uranium or plutonium, bringing at least part of the problem full circle.

 

And while India is certainly working on thorium, not all of its eggs are in that basket. India has 20 uranium-based nuclear reactors producing 4,385 MW of electricity already in operation and has another six under construction, 17 planned, and 40 proposed. The country gets props for its interest in thorium as a homegrown energy solution, but the majority of its nuclear money is still going toward traditional uranium. China is in exactly the same situation – while it promotes its efforts in the LFTR race, its big bucks are behind uranium reactors. China has only 15 reactors in operation but has 26 under construction, 51 planned, and 120 proposed.

 

 

 

The Bottom Line

 

Thorium is three times more abundant in nature than uranium. All but a trace of the world’s thorium exists as the useful isotope, which means it does not require enrichment. Thorium-based reactors are safer because the reaction can easily be stopped and because the operation does not have to take place under extreme pressures. Compared to uranium reactors, thorium reactors produce far less waste and the waste that is generated is much less radioactive and much shorter-lived.

 

To top it all off, thorium would also be the ideal solution for allowing countries like Iran or North Korea to have nuclear power without worrying whether their nuclear programs are a cover for developing weapons… a worry with which we are all too familiar at present.

 

So, should we run out and invest in thorium? Unfortunately, no. For one, there are very few investment vehicles. Most thorium research and development is conducted by national research groups. There is one publicly traded company working to develop thorium-based fuels, called Lightbridge Corp. Lightbridge has the advantage of being a first mover in the area, but on the flip side the scarcity of competitors is a good sign that it’s simply too early.

 

Had it not been for mankind’s seemingly insatiable desire to fight, thorium would have been the world’s nuclear fuel of choice. Unfortunately, the Cold War pushed nuclear research toward uranium, and the momentum gained in those years has kept uranium far ahead of its lighter, more controllable, more abundant brother to date. History is replete with examples of an inferior technology beating out a superior competitor for market share, whether because of marketing or geopolitics, and once that stage is set it is near impossible for the runner-up to make a comeback. Remember Beta VCRs, anyone? On the technical front they beat VHS hands down, but VHS’s marketing machine won the race and Beta slid into oblivion. Thorium reactors aren’t quite the Beta VCRs of the nuclear world, but the challenge they face is pretty similar: it’s damn hard to unseat the reigning champ.

 

http://www.forbes.com/sites/energysource/2012/02/16/the-thing-about-thorium-why-the-better-nuclear-fuel-may-not-get-a-chance/#3d6198bb2116