Nuclear innovation

The first advanced third-generation nuclear reactors have been in operation in Japan since 1996. Since then, technology has developed rapidly. The newer, more advanced models currently being built have a simpler design, which reduces their production and maintenance costs. They are also more efficient and safer. In addition, smaller reactors, up to 300 MW, are already being built, which in a few years may cause a lot of confusion in the nuclear market.

The technology of nuclear reactors has been developing for several decades (see also:). The first generation models were developed in 1950-1960. Second-generation designs dominate the powerful US and French nuclear navies today. They are also widespread in many countries around the world. In the classifications, the third generation (and the third +) are also distinguished, although its difference from the “two” remains quite arbitrary.

It is worth bearing in mind that more than 85% of the world's electricity generated at nuclear power plants comes from reactors that were developed on the basis of mainly military projects.

This has great consequences for the global nuclear industry, including negative ones. It is hoped that they were developed fourth generation reactors these will be civilian projects in the strict sense of the word, but so far they are only at the stage of R&D or the concept itself.

Desired number four

Modern third generation reactors have a more standardized design than previous generation reactors, which speeds up the approval process, reduces costs and construction time, and has a simpler, stronger and safer design with a longer service life, typically sixty years.

These types of reactors also make better use of fuel, leaving less waste. The fourth generation reactors should develop all the desired features of the most modern units, although the specifications, international standards and requirements for them have not yet been finalized. The most well-known and promising designs are reactors with sodium (SFR) or molten salt (MSR) as a coolant.

The salt-cooled reactor was first successfully commissioned as early as 1954, but the US still opted for water-cooled models and stopped supporting alternative designs. Currently, for example, Russia has been producing electricity since 2016 at an advanced SFR reactor that burns radioactive waste.

There are other cooling concepts in the research phase and the construction of test facilities. For the fourth generation, six are distinguished - in addition to the sodium and salt mentioned above, there are ideas for using supercritical water (SCR), gas (SCF) and bring (LBE). The sixth concept is high-temperature reactors (VHTR) with graphite as a moderator, the prototype of which was built by the Chinese by encasing radioactive fuel in graphite spheres.

Of the six possible designs, the latest generation tends to be the most credible. molten salt reactor (MSR) with liquid fuel. Molten salts of fluorine or chloride are used as a refrigerant.

Since the fuel is thorium, production of plutonium and other long-lived actinides remains very low as the process follows a decay chain. ²³²Th instead ²³⁸U. In addition, plutonium and other transuranium wastes can be used to initiate thorium. This means that nuclear waste can be used as part of the fuel mixture in the MSR.

Molten salts have excellent heat transfer properties, high boiling point, high heat capacity and low radiation damage. Therefore, this type of reactor can operate at a much safer pressure than other designs and removes heat from the core more efficiently and also prevents meltdowns and explosions. In addition, the fuel in the MSR is used even at 90%, compared with 3-4% for popular water reactors.

After hitting high-energy neutrons, the track turns into a fissile one. ²³³U, which produces less long-lived radioactive waste than z ²³⁵Ucurrently used in nuclear power plants. It has not yet been used in nuclear power, as it has traditionally been associated with research into nuclear weapons, uranium, and plutonium.

The route is not attractive to the military. Recently, NRG, the Petten Nuclear Research Center (1) on the North Sea coast in the Netherlands, in cooperation with the European Commission, has started using track as fuel and molten salt as coolant (SALIENT).

1. Molten salt reactor with a caterpillar as fuel in Petten in the Netherlands.

Sodium-cooled fast reactors (SFRs) they are suitable for the treatment of high-level waste, in particular plutonium and other actinides. Liquid metal (sodium) is used as a refrigerant instead of water. This allows the coolant to operate at higher temperatures and lower pressures than existing reactors, improving system efficiency and safety.

SFR also uses the fast neutron spectrum, which means that neutrons can be fissioned without prior moderation, as is the case in operating reactors.

Very High Temperature Reactor (VHTR) cooled by the gas flow and designed to operate at high temperatures, providing extremely efficient power generation. High temperature gas can also be used in energy-intensive processes that currently use fossil fuels such as hydrogen production, desalination, district heating, oil refining and ammonia production.

Folding reactors like Lego

If new nuclear power plants are to be built, they must be much cheaper than before.

Energy companies are being forced to look for more efficient nuclear solutions after stories like failed investments in a traditional nuclear power plant in South Carolina, USA. Its construction costs increased consumers' electricity bills by a fifth, and after $9 billion was sunk, construction on the plant was halted. Similar events have taken place in other countries, such as the UK. In Finland, the construction of a new reactor at the Olkiluoto power plant is already eight years behind schedule and over budget by more than $6,5 billion.

These six concepts appear to be more efficient and safer than current standards, greatly reducing implementation costs, but experts want more - they want modular reactors made from prefabricated, factory-assembled Lego-like blocks and small reactors (SMRs) that are much more flexible to use.

There are many startups working on miniature designs. Many promise, like Oklo, systems ready by 2025. The better-known company NuScale is considered a leader in mini-nuclear technology and aims to build a dozen 2026-megawatt reactors by 60 with Utah's Associated Municipal Power Systems.

The MIT Tech Review, however, cools the optimism and notes that less than a decade ago, a small modular reactor manufacturer like NuScale had already promised such things, but the plan collapsed after it failed to find enough customers.

Another innovative company, TerraPower, founded by Bill Gates, hopes to launch a prototype in the 20s.advanced wave reactor"(DVR). The TWR concept has been around for decades. Instead of relying solely on enriched uranium, depleted uranium, especially the waste left over from enrichment plants, should be used as refueling fuel.

Initially, enriched uranium is used, but then reactors can operate on depleted uranium for decades. Liquid sodium is used as a coolant that transfers heat from the reactor to the rotation of the steam turbine.

TWR proponents say such reactors remain safer than traditional water-cooled models because they operate at lower pressures and are not subject to a fuel spill explosion like the one that occurred in 1986 at Chernobyl. However, some experts believe that working with liquid sodium is extremely difficult due to the possibility of leakage and the high chemical activity of the material.

Another technology from the same laboratory, known as Molten Chlorine Fast Reactor (MCFR), is not as advanced in operation, but promises further improvements in efficiency and economy. The MCFRs will use molten salt both as a heat transfer medium and as a fuel medium.

For now, however, molten-salt reactor maker Transatomic Power suspended operations in September 2018, believing it could not complete its projects. Modular reactor companies often suffer from a loss of investor interest. In 2011

Generation mPower, a developer of small SMRs, had contracts to build up to six NuScale reactors, but investment was delayed and a lack of orders eventually led to the closure of the entire project.

Fortunately, new initiatives are constantly emerging. Canadian company Terrestrial Energy plans to build a 190 MW power plant in Ontario, where by 2030 the first small molten salt reactors will produce energy at a cost competitive with investments using natural gas in the lead role.

We already know about at least one fourth-generation reactor, which may soon be put into operation.

It is reported that the state-owned China National Nuclear Corporation has a prototype high-temperature reactor. power 210 MWwhich this year should be connected to the grid in the eastern province of Shantung. It is cooled with helium and can operate at temperatures up to 1000°C.

Another project from the Middle Kingdom is the initiative of the Chinese Ministry of Natural Resources to build a small modular reactor. ACP100 in Changjiang, Hainan. It will be put into operation as early as 2025, and the target capacity will be 125 MW.

After several previous unsuccessful projects, including a complete abandonment in 2014 of attempts to enter the MMP market, the company Westinghouse, whose nuclear technology is being seriously considered by the Polish authorities in the context of domestic investment in nuclear power, which has been in preparation for years, announces a multi-million dollar investment to demonstrate the readiness of its eVinci microreactor (2) 25 MW for normal operation as early as 2022.

2. Diagram of the Westinghouse eVinci microreactor.

According to Power Magazine, the eVinci project will operate autonomously. The reactor core is a solid steel monolith, in which there are channels for fuel elements, a moderator (metal hydride) and heat pipes arranged hexagonally, also acting as a coolant between the fuel channels and heat pipes. The latter will extract heat from the core using technology based on thermal conductivity and liquid phase transition. Process heat up to 600°C will be used for petrochemical and other industrial purposes.

Other leaders of the "small" nuclear industry, the Russians, seem to be betting on floating power plants.

The state nuclear company Rosatom has completed the construction of the first industrial floating nuclear power plant, after which it was successfully towed to its destination in the Russian Far East, where access to energy is difficult.

Floating power plant Academic homonosov hosts two 35-megawatt nuclear power plant project reactors located on a floating platform and capable of delivering 70 MW of electricity to the city. residents.

Experiments with small modular SMR reactors are being carried out in many countries. In the UK he's working on it Rolls-Royce (3), and in China, the aforementioned company CNNC, which, like Russia, wants to install devices on ships.

3. Rolls-Royce Mini-Actor Vision

However, experts firmly argue that SMRs will not replace large industrial reactors. Per unit of generated power, the investment costs for their construction are much higher than for nuclear power plants built so far.

And since these are prototypes so far, the exact costs are not even known yet. However, there is a suspicion that economies of scale - in this case small scale - will work against them.

According to experts, including the authors of the report of the Polish National Center for Nuclear Research, SMR reactors can be valuable addition energy systems – for example, for power plants that have hitherto been operated for special purposes.

Theoretically, they can also be an excellent solution for locations far from transmission networks (for example, northern Russia, USA) or in countries with a low total power system capacity, where the use of large blocks is difficult due to grid balance.

Temporary sarcophagi

Designers of new types of reactors often emphasize the ability of their design to "burn" or neutralize hazardous radioactive waste.

The issue of handling such waste continues to be one of the most serious problems of nuclear energy and the main reason for public opposition to the further development of nuclear energy.

The case returned to the world media a few months ago with reports of the threat of a collapse. Runit Dome (4) - a huge concrete dome in the Marshall Islands, which stores nuclear waste, including an extremely dangerous isotope ²³⁹Pu. The products of nuclear reactions come from 67 nuclear bomb explosions that occurred between 1946 and 1958. The nuclear grave contains as many as 110 explosions. m³ radioactive materials.

It turned out that due to the penetration of the salty waters of the Pacific Ocean, the structure began to crack. A possible leak - threatening literally at any moment - could have global consequences, greater than Chernobyl or Fukushima. The facility was quickly built in 1979 when the US Department of Energy became aware of the catastrophic impact of hazardous substances on the marine ecosystem. The problem is that at that time it was not assumed that the facility would not be modernized for many decades.

In turn, the famous Chernobyl reactor No. 4 will remain unsafe fortens of thousands of years. In July 2019, thirty-three years after the explosion, 200 tons of uranium, plutonium, liquid fuel and irradiated dust were finally surrounded by a 40 1,5 square foot steel and concrete sarcophagus. tons worth EUR XNUMX billion. The new sarcophagus will safely stand for about a hundred years, after which, unfortunately, its condition will begin to deteriorate, and future generations will have to decide what to do next.

Radioactive material is typically produced in large quantities at every step in the production of nuclear energy, from uranium mining and enrichment to reactor operation and spent fuel reprocessing.

Over the eighty years of nuclear energy, 450 industrial reactors have been built, as well as many experimental stations and tens of thousands of nuclear warheads, and a large stock of waste of various levels has been accumulated.

"Unsolvable Problem"

According to the International Atomic Energy Agency, only about 0,2-3% of the volume is high-level waste (5). This is the most dangerous material that remains radioactive for tens of thousands of years.

It requires constant refrigeration and protection and contains 95% of the radioactivity associated with nuclear power generation. Another 7% by volume, known as intermediate activity wasteconsists of reactor elements and graphite cores.

This is also a very dangerous set, but it can be stored in special containers because it does not give off too much heat. The rest is huge sums of so-called low level and very low level waste, mainly consisting of scrap metal, paper, plastic, building elements and any other radioactive materials associated with the operation and dismantling of nuclear installations.

It is believed that approx. 22 species. m³ high level solid waste; and unknown quantities in China, Russia and military bases.

Another 460 thousand. m³ buried wastes are characterized by moderate activity. And about 3,5 million m³ are classified as low-level waste. However, these are only official estimates. The actual amount of radioactive waste may be much higher. Some reports state that up to 90 pieces are produced annually in the United States alone. m³ high level waste.

In the early days of nuclear energy, virtually no waste was considered. Authorities, incl. The British, Americans and Russians then threw them into the sea or rivers, including over 150 people. tons of low-level waste. Since then, billions of dollars have been spent trying to figure out the best way to reduce production and then keep it for eternity.

Many ideas have already emerged, but most of them have been rejected as impractical, too expensive, or environmentally unacceptable. These include launching waste into space, sequestering it in synthetic rock, burying it in layers of ice, dumping it on the world's most isolated islands, and dumping it in the world's deepest ocean trenches.

The proposed solutions based not on reprocessing (for example, in fourth generation reactors), but on storage, can be divided into two groups: packaging and placement in some place, preferably remote and secluded, or binding of a radioactive substance in the form of cement, salt, glass, slag, and put in a safe place.

In the US, by law, all US high-level waste must be sent to Yucca Mountains in Nevada, about 140 km northwest of Las Vegas - designated as a deep geological repository since 1987. However, this injunction led to ongoing legal, regulatory and constitutional issues, becoming the subject of political controversy.

Shoshone Indians, Nevadas, and other groups have been fighting the landfill for years. Despite the fact that a huge tunnel was cut there (6), the permit for its use was never issued, and the area is now almost deserted. It is not even known what to do with it, although the Trump administration wants to return to the project.

6. Entrance to the storage of nuclear waste in Mount Yucca, Nevada.

In the UK, the government offered money to local communities but failed to convince any local government to maintain a permanent deep waste repository.

Massive protests against the disposal of radioactive debris in France and Germany contributed to the popularity of the Green Party and indefinitely delayed or halted work on the proposed repositories. Only Finland appears to be close to completing a deep repository for high-level waste.

In May, work began on an "encapsulation" plant, where waste will be packed in copper canisters and taken out into underground tunnels up to 500 m deep. However, the long-term safety of the canisters is still in doubt.

Paul Dorfman, founder of the Nuclear Consulting Group, a group of international scientists and independent experts in the field of radioactive waste, nuclear policy and environmental risks, writes in The Guardian.

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Laser transmutation

However, the search for meaningful concepts continues. Recently, inspired by hydraulic fracturing, the idea arose to drill vertical wells up to 5 meters deep. to me injectable into the crevices of rocks of an unpleasant substance, something like fissures in the process of extracting shale gas.

Deep Isolation, founded by Liz Mueller and her father Richard Muller, a professor at the University of California at Berkeley, is known for such projects. Some scientists say that this option is promising, but there are doubts, since the extraction of vertical drilling waste may be almost impossible.

Another technology known as transmutationaims to reduce radiotoxicity through the use of lasers to convert (transmute) atoms into hazardous isotopes. It has been studied for decades in the UK, USA, Sweden and other countries, but without much success.

However, this idea was returned in December 2018 thanks to the French physicist Gerard Moore (7), Nobel Prize winner, who, in his lecture on the occasion of the Nobel Prize, spoke about the possibility of using laser beams to neutralize radioactive atomic nuclei.

Muru says that the time for a radioactive waste emergency to occur could potentially be reduced from thousands of years to a few...minutes! However, he reserves that the laser version for radioactive waste, which he and Prof.

Toshiki Tajima at the University of Irvine in California needs many more years of research. Muru and Tajima want to create super fast accelerator controlled by a laser that produces a beam of protons that can penetrate atoms. The main task is to shorten the beam - it is not easy to solve it.

Perhaps the final solution to the problems will once again be thermonuclear fusion. By 2030, China announces the construction of a new hybrid reactor (8) that will be able to "burn" radioactive waste through nuclear fusion.

8. Visualization of a promising nuclear hybrid reactor

Traditional nuclear power plants produce a large amount of waste, the main component of which is uranium-238, which cannot be used in modern fission reactors. The proposed hybrid reactor would use nuclear fusion to decompose. ²³⁸Theoretically, it is even possible to process waste from traditional reactors into new fuel.

The project is being developed at the Chinese Academy of Physics and Engineering in Sichuan, a top-secret military research center that also conducts experiments with Chinese nuclear weapons. The heart of the proposed hybrid power plant will be a fusion reactor powered by an electric current of 60 trillion amperes.

The reactor will be covered with a shell filled with uranium-238. High-speed neutrons generated by fusion split atoms. ²³⁸U, which could produce a large amount of energy to support fusion and thus significantly reduce the amount of energy coming from outside. The whole system will focus on the complete consumption of nuclear fuel and the prevention of the formation of any radioactive waste.

prof. Wang Hongwen, deputy director of the hybrid reactor project, said in a press statement that key components will be developed and tested as early as around 2020, and the experimental reactor will be completed by 2030. A hybrid reactor may be easier to build, he says, in part because it only needs a fifth of the external energy of a "pure fusion" reactor to keep it running.