April 9, 2016 at 21:30Fourth generation
Nuclear energy is deservedly considered one of the most conservative industries that has reached the pinnacle of its path on its S-curve. For the past 25 years, an external observer would not notice a change in key technology - all the same assemblies of fuel elements, heating or boiling water, with the conversion of thermal energy into electrical energy. All the more surprising is the fact that nuclear energy sees its future in 6 revolutionary concepts, each of which in its own way shifts the paradigm of nuclear energy in one direction or another.
MSRE Research Reactor Housing, 70s
It is also important that all these concepts did not arise today, but at the dawn of the birth of the nuclear industry and lost the competition for the title of industry standard for pressurized water reactors (PWR in Western terminology or BBER in Russian). However, as in the case of electric vehicles, the gradual accumulation of the amount of technology can return to the pedestal of forgotten heroes of the dawn of the atomic age.
Fourth generation
From the beginning, it is customary to divide the development of nuclear energy into 3.5 unequal generations, where the former was noted by dozens of different concepts, sometimes very strange in our opinion (for example, the British Magnox reactors with graphite moderator and circulating compressed carbon dioxide as a coolant), the latter, the two most severe accidents in the history of energy, and the third and third plus - the prevalence of financiers over engineers. To this day, the wonders and enthusiasm of the atomic age have given way to an era when a 2-3 percent improvement in the performance of nuclear power plants is a revolutionary achievement, widely discussed in the relevant press.
The fourth generation should be beyond the confines of nuclear power. To do this, it will be necessary to solve several conflicting tasks at once - not to lose the safety of the reactor, improve or at least not worsen its economy and solve the problem of switching from using 235U to 238U .
6 concepts selected by the international organization Generation IV International Forum are trying to solve these problems from different angles. Which of them will become (and will it become) the basis for the development of the nuclear industry in the 21st century should be shown by studies of the next 15 years.
Sodium Fast Reactor
This type of reactor stands out sharply from the entire “team” with its sophistication and even some everyday life. A key feature of this reactor is its fast neutron spectrum, which allows for a closed nuclear fuel cycle. However, these are not provided free of charge, and the two most complexities in such a reactor are fire hazardous sodium and damage to the structures of the core by fast neutrons. Nevertheless, in the 60s, at the time of the emergence of nuclear energy, fast sodium was considered the simplest on the way to closing the fuel cycle. And the nuclear fuel cycle, in turn, seemed necessary for the construction of thousands of reactors, for which 235 isotope of uranium simply would not be enough.
The most “adult” and powerful representative of fast sodium reactors is BN-800.
As a result, BN-type reactors went the longest way (20 ever built and functioning) from the first experimental plants to full-fledged power plants - Phenix and Superphenix in France, BN-600 in the USSR and BN-800 in Russia. At the beginning of the 80s, it seemed quite obvious that by 2020 hundreds and thousands of gigawatts of exactly fast sodium reactors would work in the world. However, a sharp slowdown in the growth of nuclear energy and a variety of circumstances, such as the arrival of the "green" in power in France or the collapse of the USSR, broke this rise. In France, by the way, from 1995 to 1998, all elements of the nuclear fuel cycle were functioning - a plutonium-fuel reader, a spent fuel processing plant, and a fresh fuel fabrication plant ... Device and characteristics of the French non-flying Super Phenix
Today, fast sodium reactors with oxide or denser fuels from a mixture of U238 and Pu239 froze one step away from starting to replace reactors with pressurized water, and are quite widely switched on (5-10 blocks in a 10-15 year term and up to the basics of energy 30-50 years old) into the plans for the development of nuclear energy in the four countries that are really developing it - India, China, Russia and South Korea.
Reactor room of the Indian sodium BR FBR
The key installations in this area today are BN-600, BN-800 in Russia, planned by MBIR at our place, and PFBR pilot plants in India, ASTRID in France.
Fast lead reactor
In contrast to the previous one, molten lead coolant reactors exist only on paper. This type was invented in an attempt to overcome the problems of BNov - sodium fire hazard (and related technical complications - see the article on BREST for more details ), boiling of sodium in AZ during accidents and the associated danger of acceleration of the reactor using instant neutrons . Another “emergency” advantage of lead is the retention of particularly unpleasant volatile fission products of uranium - iodine and cesium in the coolant and shielding of nuclear fuel from gamma radiation.
BREST-OD-300 - the most advanced lead reactor project in the world today
Of course, lead also has disadvantages. The most important is the high melting point (327 C), which means great care for maintaining the coolant in the molten state. Also known are the problems of lead corrosion of steel, poor compatibility with oxide (the most common) fuel, and in general, we can talk about the low level of sophistication of this type of reactor. Interestingly, on the basis of the idea of the evolution of sodium breeders in the USSR, a rather revolutionary BREST project was born, optimal for the slow development of nuclear energy. In addition to lead, the key to it is the idea of charging fissile material once - at the start, and then replenishment exclusively with U238.
A collage of photos of the development and development of elements BREST-OD-300. Such work takes thousands of man-hours and costs billions of rubles.
Sometimes lead-bismuth reactors are added to the lead cohort. Adding bismuth to the coolant lowers its melting point to “sodium” values - about 100 C. Reactors with such coolant were put into serial production of submarines 705 of the project, but with all the proximity it is impossible to transfer one technology to another.
The ALFRED reactor with lead coolant is a smaller and simpler BREST project, but also with less technical risk.
BREST, along with the European ALFRED projects, are by far the only “live” lead projects with funding and the likelihood of construction. In addition, there is a Belgian MYRRHA reactor with lead coolant being created, but it is an exotic and unique ADS system where the neutron flux needed to operate at power will be created by an accelerator source. However, the real advantages and disadvantages of lead reactors compared to sodium are unlikely to be understood before 2030.
ALFRED is planned for construction in the 20s.
Gas Cooled Fast Reactor
Today's gaseous coolant reactors are the Chinese development of the German HTR branch. They have such a balanced set of pros and cons that the nuclear industry does not see in them the development potential except one, which is described below. Gas reactors of the future should be different - breeders with a fast neutron spectrum (which, incidentally, is very nontrivial for an active zone with helium - a wonderful neutron moderator), cooled by inert helium, and generating electricity on a gas turbine.
Installation of the shell of the new Chinese gas reactor 03/25/2016
Today, gas-cooled reactors have not received much development due to a variety of reasons, the main of which is that in case of an accident such as LOCA (pipeline rupture with loss of tightness of the reactor) there is nothing to cool the core. In order to somehow cope with this, heat in the event of an accident is removed through the walls, and the dimensions of the AZ are inflated ten times in comparison with water-cooled reactors. In the fourth generation, this problem will have to be solved, and if it succeeds, the “gas fast” can sparkle with completely new colors, with their very high efficiency.
Design image of a GT-MGR with a gas turbine, the gas turbine generator itself and the characteristics of the reactor installation. No steam generators.
Such a single-circuit high-temperature approach, along with a completely different type of fuel (instead of a high-tech engineering product that runs on fuel in PWR / BWR / VVER, something like sculpting millions of graphite bricks or balls with uranium particles inside) theoretically allows for very cheap atomic energy. So far, however, this is far from that - to get a breeder with a helium coolant and high temperature.
An important advantage of gas reactors is the inertness and inactivability of helium used as a coolant. The flip side is the significant energy consumption for pumping helium through the core. ALLEGRO
gas-cooled fast reactor
And a promising powerful gas-cooled fast GFR reactor. It would be interesting to understand how they plan to cool the fuel with the reactor open ...
Today, the only active project in this area is the European small research reactor ALLEGRO, with a thermal capacity of 75 megawatts, using plutonium fuel. His task is to study the issues facing the designers of the large (2400 megawatts of thermal) promising European gas breeder GFR. One of the most difficult is the high temperature of fuel and helium. One can also note the domestic GT-MGR project , which was once being developed as an alternative to the BN-800.
And a little more manufacture of the Chinese HTR-PM. This time a steam generator is docked to the reactor vessel.
However, the high temperature competition for gas-cooled reactors is ... gas-cooled reactors that exist today.
High-temperature gas reactor
The younger brother of concept No. 3 whose main task is to be a source of nuclear heat for the chemical and metallurgical industries. For this, the helium exhaust from the reactor must be heated to 900 and above degrees Celsius. This direction was included in the list of perspectives mainly due to the surge of interest in hydrogen energy in the 90s, when such plants were supposed to produce hydrogen (a lot of hydrogen!) From the water in a pyrochemical way.
Estimated hydrogen production station using VGTR. Perhaps hydrogen will still be needed by the energy industry of the future, as an energy accumulator for systems dominated by renewable energy.
The main difference from the previous concept is that, for the sake of high temperature, VTGR will refuse from fuel bridging and NFCF. The technical basis for this type is the existing gas-cooled reactors with bulk ball (TRISO) or prismatic fuel. At the Japanese HTTR research reactor , in particular, a helium temperature of 850 ° C has already been obtained.
Uranium microspheres dispersed in graphite blocks are one of the fuel options for gas-cooled reactors.
However, not very big difficulties (compared to other participants) with implementation do not make HTGR a favorite - along with the fading interest in hydrogen energy, the desire to invest in nuclear heat sources has disappeared. Today, the only ones who are developing this area are the Chinese, who are building the first experimental-industrial unit HTR-PM and have big plans for developing this area. However, it is possible that when coal becomes too expensive or inconvenient for industrial heat, we will still see the heyday of HTGR
Single-circuit supercritical water reactor
At a pressure above 225 atmospheres and a temperature above 374 degrees, the water ceases to boil and turns into something between a liquid and steam. If we take and try to “disperse” the usual PWR / VVER to such coolant parameters, we can get many unusual advantages
Structurally, such reactors differ little from the usual VVER, all the subtleties in the design of fuel.
Moreover, in the thermal power industry there is a lot of experience in creating steam-powered blocks based on supercritical steam, i.e. problems like creating a gigawatt gas turbine for gas-cooled reactors will not arise. The vast experience of today's nuclear energy in the development of PWR / VVER plays into the hands.
Fuel for such reactors has cavities and channels for moving elements that change neutron deceleration - spectral regulation of the reactor
The main obstacle to the implementation of this direction is steam aggressiveness at a pressure of 250 atmospheres and a temperature of 560 degrees (which are planned to be achieved in the ORSV projects), which means a large amount of new materials and structures. It is not easy to create a reactor vessel for such parameters, despite the fact that 43% promise fast reactors with metal coolants.
In addition, the Americans are supposed to repeatedly pass the coolant through the core.
Today, the main research on the topic of ARDS is conducted in Russia and Japan and the USA, where VVER-SKD projects (link to a large review article) and Japanese SCFR and RMWR and American HPLWR are all completely paper-based.
Liquid salt reactor
The holy grail of nuclear energy, the place of worship of all reactor designers. A homogeneous molten mixture of beryllium / sodium fluorides and uranium / plutonium / thorium fluoride forms a liquid core, which is not afraid of radiation resistance problems. Continuous selection and purification of part of the salt from decay products (including neutron poisons) allows you to maintain the highest level of fuel reproduction and automatically forms a closed nuclear fuel cycle directly at the station. The reactor can be easily shut off, for example by draining the core into a trap where it will not be critical. Moreover, the drain line can be plugged for a while by normal operation with a frost-free stopper from the fuel mixture, i.e. in case of loss of control, the stop and localization of the AZ will occur automatically.
European projects JSR. Where other projects have the most complicated core mechanics, JSR has a completely Buddhist void.
In addition, JSS is the most convenient (along with heavy water) for involving thorium in the fuel cycle.
In addition to serious guys from Gen 4 IF, liquid salt reactors are also offered for use by various startups.
As usual, the advantages are simultaneously disadvantages. The absence of one of the barriers to the spread of radioactivity (cladding of fuel elements) raises questions among atomic inspectors. The constant presence of literally the entire periodic table in the melt causes great problems with the corrosion resistance of the reactor vessel. The presence of a large radiochemical plant near the reactor, in addition to radiophobic issues, also gives rise to problems with the non-proliferation of nuclear materials. After all, JSS is not only a manufacturer of weapons-grade - but better than weapons-grade plutonium on a very tangible scale. In fact, at such a nuclear power plant it will be possible to produce weapons of material for dozens of nuclear bombs per year.
Another JSR from startup Transatomic Power. The frequency of access to liquid salt in startups is alarming.
In the 20th century, two small liquid salt reactors operated in the United States - Aircraft Reactor Experiment (ARE) and Molten Salt Reactor Experiment (MSRE), and only the second of them was successful, and is believed to have been closed in 1976 in favor of much more successful (and in something simpler) fast reactors with sodium coolant. ( An interesting documentary in English about MSRE)
MSRE reactor. Here 1 is the reactor, 2 is the heat exchanger of 1-2 circuits, 3.6 are the circulation pumps, 7.8.9 are the heat removal system from the reactor to the air, 10.11 are the salt melt drain tanks, 13 is the freezing plug for emergency discharge salt.
Today, despite the regularly arising interest in this “ideal nuclear reactor”, there is not a single project supported by financing to build at least a research facility. Only paper reactors are being developed, such as MOSART or MSFR or startup projects. However, the potential promise makes us carry out a variety of supporting studies (for example, on corrosion resistance) in the hope that someday progress in other areas (for example, in materials) will give impetus to the development of JSS.
Conclusion
If a persistent interest in atomic energy re-emerged in the world, the industry in the zagashniki has developments capable of solving many problems of sustainable supply of civilization with energy. However, in a situation where all the buns go to a renewable source, most likely for most of the promising concepts of reactors we will see only experimental plants and their leisurely development.
MSRE Research Reactor Housing, 70s
It is also important that all these concepts did not arise today, but at the dawn of the birth of the nuclear industry and lost the competition for the title of industry standard for pressurized water reactors (PWR in Western terminology or BBER in Russian). However, as in the case of electric vehicles, the gradual accumulation of the amount of technology can return to the pedestal of forgotten heroes of the dawn of the atomic age.
Fourth generation
From the beginning, it is customary to divide the development of nuclear energy into 3.5 unequal generations, where the former was noted by dozens of different concepts, sometimes very strange in our opinion (for example, the British Magnox reactors with graphite moderator and circulating compressed carbon dioxide as a coolant), the latter, the two most severe accidents in the history of energy, and the third and third plus - the prevalence of financiers over engineers. To this day, the wonders and enthusiasm of the atomic age have given way to an era when a 2-3 percent improvement in the performance of nuclear power plants is a revolutionary achievement, widely discussed in the relevant press.
The fourth generation should be beyond the confines of nuclear power. To do this, it will be necessary to solve several conflicting tasks at once - not to lose the safety of the reactor, improve or at least not worsen its economy and solve the problem of switching from using 235U to 238U .
6 concepts selected by the international organization Generation IV International Forum are trying to solve these problems from different angles. Which of them will become (and will it become) the basis for the development of the nuclear industry in the 21st century should be shown by studies of the next 15 years.
Sodium Fast Reactor
This type of reactor stands out sharply from the entire “team” with its sophistication and even some everyday life. A key feature of this reactor is its fast neutron spectrum, which allows for a closed nuclear fuel cycle. However, these are not provided free of charge, and the two most complexities in such a reactor are fire hazardous sodium and damage to the structures of the core by fast neutrons. Nevertheless, in the 60s, at the time of the emergence of nuclear energy, fast sodium was considered the simplest on the way to closing the fuel cycle. And the nuclear fuel cycle, in turn, seemed necessary for the construction of thousands of reactors, for which 235 isotope of uranium simply would not be enough.
The most “adult” and powerful representative of fast sodium reactors is BN-800.
As a result, BN-type reactors went the longest way (20 ever built and functioning) from the first experimental plants to full-fledged power plants - Phenix and Superphenix in France, BN-600 in the USSR and BN-800 in Russia. At the beginning of the 80s, it seemed quite obvious that by 2020 hundreds and thousands of gigawatts of exactly fast sodium reactors would work in the world. However, a sharp slowdown in the growth of nuclear energy and a variety of circumstances, such as the arrival of the "green" in power in France or the collapse of the USSR, broke this rise. In France, by the way, from 1995 to 1998, all elements of the nuclear fuel cycle were functioning - a plutonium-fuel reader, a spent fuel processing plant, and a fresh fuel fabrication plant ... Device and characteristics of the French non-flying Super Phenix
Today, fast sodium reactors with oxide or denser fuels from a mixture of U238 and Pu239 froze one step away from starting to replace reactors with pressurized water, and are quite widely switched on (5-10 blocks in a 10-15 year term and up to the basics of energy 30-50 years old) into the plans for the development of nuclear energy in the four countries that are really developing it - India, China, Russia and South Korea.
Reactor room of the Indian sodium BR FBR
The key installations in this area today are BN-600, BN-800 in Russia, planned by MBIR at our place, and PFBR pilot plants in India, ASTRID in France.
Fast lead reactor
In contrast to the previous one, molten lead coolant reactors exist only on paper. This type was invented in an attempt to overcome the problems of BNov - sodium fire hazard (and related technical complications - see the article on BREST for more details ), boiling of sodium in AZ during accidents and the associated danger of acceleration of the reactor using instant neutrons . Another “emergency” advantage of lead is the retention of particularly unpleasant volatile fission products of uranium - iodine and cesium in the coolant and shielding of nuclear fuel from gamma radiation.
BREST-OD-300 - the most advanced lead reactor project in the world today
Of course, lead also has disadvantages. The most important is the high melting point (327 C), which means great care for maintaining the coolant in the molten state. Also known are the problems of lead corrosion of steel, poor compatibility with oxide (the most common) fuel, and in general, we can talk about the low level of sophistication of this type of reactor. Interestingly, on the basis of the idea of the evolution of sodium breeders in the USSR, a rather revolutionary BREST project was born, optimal for the slow development of nuclear energy. In addition to lead, the key to it is the idea of charging fissile material once - at the start, and then replenishment exclusively with U238.
A collage of photos of the development and development of elements BREST-OD-300. Such work takes thousands of man-hours and costs billions of rubles.
Sometimes lead-bismuth reactors are added to the lead cohort. Adding bismuth to the coolant lowers its melting point to “sodium” values - about 100 C. Reactors with such coolant were put into serial production of submarines 705 of the project, but with all the proximity it is impossible to transfer one technology to another.
The ALFRED reactor with lead coolant is a smaller and simpler BREST project, but also with less technical risk.
BREST, along with the European ALFRED projects, are by far the only “live” lead projects with funding and the likelihood of construction. In addition, there is a Belgian MYRRHA reactor with lead coolant being created, but it is an exotic and unique ADS system where the neutron flux needed to operate at power will be created by an accelerator source. However, the real advantages and disadvantages of lead reactors compared to sodium are unlikely to be understood before 2030.
ALFRED is planned for construction in the 20s.
Gas Cooled Fast Reactor
Today's gaseous coolant reactors are the Chinese development of the German HTR branch. They have such a balanced set of pros and cons that the nuclear industry does not see in them the development potential except one, which is described below. Gas reactors of the future should be different - breeders with a fast neutron spectrum (which, incidentally, is very nontrivial for an active zone with helium - a wonderful neutron moderator), cooled by inert helium, and generating electricity on a gas turbine.
Installation of the shell of the new Chinese gas reactor 03/25/2016
Today, gas-cooled reactors have not received much development due to a variety of reasons, the main of which is that in case of an accident such as LOCA (pipeline rupture with loss of tightness of the reactor) there is nothing to cool the core. In order to somehow cope with this, heat in the event of an accident is removed through the walls, and the dimensions of the AZ are inflated ten times in comparison with water-cooled reactors. In the fourth generation, this problem will have to be solved, and if it succeeds, the “gas fast” can sparkle with completely new colors, with their very high efficiency.
Design image of a GT-MGR with a gas turbine, the gas turbine generator itself and the characteristics of the reactor installation. No steam generators.
Such a single-circuit high-temperature approach, along with a completely different type of fuel (instead of a high-tech engineering product that runs on fuel in PWR / BWR / VVER, something like sculpting millions of graphite bricks or balls with uranium particles inside) theoretically allows for very cheap atomic energy. So far, however, this is far from that - to get a breeder with a helium coolant and high temperature.
An important advantage of gas reactors is the inertness and inactivability of helium used as a coolant. The flip side is the significant energy consumption for pumping helium through the core. ALLEGRO
gas-cooled fast reactor
And a promising powerful gas-cooled fast GFR reactor. It would be interesting to understand how they plan to cool the fuel with the reactor open ...
Today, the only active project in this area is the European small research reactor ALLEGRO, with a thermal capacity of 75 megawatts, using plutonium fuel. His task is to study the issues facing the designers of the large (2400 megawatts of thermal) promising European gas breeder GFR. One of the most difficult is the high temperature of fuel and helium. One can also note the domestic GT-MGR project , which was once being developed as an alternative to the BN-800.
And a little more manufacture of the Chinese HTR-PM. This time a steam generator is docked to the reactor vessel.
However, the high temperature competition for gas-cooled reactors is ... gas-cooled reactors that exist today.
High-temperature gas reactor
The younger brother of concept No. 3 whose main task is to be a source of nuclear heat for the chemical and metallurgical industries. For this, the helium exhaust from the reactor must be heated to 900 and above degrees Celsius. This direction was included in the list of perspectives mainly due to the surge of interest in hydrogen energy in the 90s, when such plants were supposed to produce hydrogen (a lot of hydrogen!) From the water in a pyrochemical way.
Estimated hydrogen production station using VGTR. Perhaps hydrogen will still be needed by the energy industry of the future, as an energy accumulator for systems dominated by renewable energy.
The main difference from the previous concept is that, for the sake of high temperature, VTGR will refuse from fuel bridging and NFCF. The technical basis for this type is the existing gas-cooled reactors with bulk ball (TRISO) or prismatic fuel. At the Japanese HTTR research reactor , in particular, a helium temperature of 850 ° C has already been obtained.
Uranium microspheres dispersed in graphite blocks are one of the fuel options for gas-cooled reactors.
However, not very big difficulties (compared to other participants) with implementation do not make HTGR a favorite - along with the fading interest in hydrogen energy, the desire to invest in nuclear heat sources has disappeared. Today, the only ones who are developing this area are the Chinese, who are building the first experimental-industrial unit HTR-PM and have big plans for developing this area. However, it is possible that when coal becomes too expensive or inconvenient for industrial heat, we will still see the heyday of HTGR
Single-circuit supercritical water reactor
At a pressure above 225 atmospheres and a temperature above 374 degrees, the water ceases to boil and turns into something between a liquid and steam. If we take and try to “disperse” the usual PWR / VVER to such coolant parameters, we can get many unusual advantages
- the most obvious - the efficiency of the installation will increase from 33% to 42-43%
- power will rise 1.5 times with approximately the same size and cost of the reactor.
- less obvious - due to the high heat capacity of the resulting coolant, it is possible to increase the ratio of the amount of uranium to water in the core and to obtain a reactor with an intermediate neutron spectrum with a fuel reproduction rate in AZ of 0.8-1, i.e. almost close the nuclear fuel cycle.
- due to the lack of boiling in the AZ, it is much easier to make a single-loop reactor installation - as in the BWR “boilers”, which further reduces the amount of equipment needed to obtain a full-fledged nuclear power plant.
Structurally, such reactors differ little from the usual VVER, all the subtleties in the design of fuel.
Moreover, in the thermal power industry there is a lot of experience in creating steam-powered blocks based on supercritical steam, i.e. problems like creating a gigawatt gas turbine for gas-cooled reactors will not arise. The vast experience of today's nuclear energy in the development of PWR / VVER plays into the hands.
Fuel for such reactors has cavities and channels for moving elements that change neutron deceleration - spectral regulation of the reactor
The main obstacle to the implementation of this direction is steam aggressiveness at a pressure of 250 atmospheres and a temperature of 560 degrees (which are planned to be achieved in the ORSV projects), which means a large amount of new materials and structures. It is not easy to create a reactor vessel for such parameters, despite the fact that 43% promise fast reactors with metal coolants.
In addition, the Americans are supposed to repeatedly pass the coolant through the core.
Today, the main research on the topic of ARDS is conducted in Russia and Japan and the USA, where VVER-SKD projects (link to a large review article) and Japanese SCFR and RMWR and American HPLWR are all completely paper-based.
Liquid salt reactor
The holy grail of nuclear energy, the place of worship of all reactor designers. A homogeneous molten mixture of beryllium / sodium fluorides and uranium / plutonium / thorium fluoride forms a liquid core, which is not afraid of radiation resistance problems. Continuous selection and purification of part of the salt from decay products (including neutron poisons) allows you to maintain the highest level of fuel reproduction and automatically forms a closed nuclear fuel cycle directly at the station. The reactor can be easily shut off, for example by draining the core into a trap where it will not be critical. Moreover, the drain line can be plugged for a while by normal operation with a frost-free stopper from the fuel mixture, i.e. in case of loss of control, the stop and localization of the AZ will occur automatically.
European projects JSR. Where other projects have the most complicated core mechanics, JSR has a completely Buddhist void.
In addition, JSS is the most convenient (along with heavy water) for involving thorium in the fuel cycle.
In addition to serious guys from Gen 4 IF, liquid salt reactors are also offered for use by various startups.
As usual, the advantages are simultaneously disadvantages. The absence of one of the barriers to the spread of radioactivity (cladding of fuel elements) raises questions among atomic inspectors. The constant presence of literally the entire periodic table in the melt causes great problems with the corrosion resistance of the reactor vessel. The presence of a large radiochemical plant near the reactor, in addition to radiophobic issues, also gives rise to problems with the non-proliferation of nuclear materials. After all, JSS is not only a manufacturer of weapons-grade - but better than weapons-grade plutonium on a very tangible scale. In fact, at such a nuclear power plant it will be possible to produce weapons of material for dozens of nuclear bombs per year.
Another JSR from startup Transatomic Power. The frequency of access to liquid salt in startups is alarming.
In the 20th century, two small liquid salt reactors operated in the United States - Aircraft Reactor Experiment (ARE) and Molten Salt Reactor Experiment (MSRE), and only the second of them was successful, and is believed to have been closed in 1976 in favor of much more successful (and in something simpler) fast reactors with sodium coolant. ( An interesting documentary in English about MSRE)
MSRE reactor. Here 1 is the reactor, 2 is the heat exchanger of 1-2 circuits, 3.6 are the circulation pumps, 7.8.9 are the heat removal system from the reactor to the air, 10.11 are the salt melt drain tanks, 13 is the freezing plug for emergency discharge salt.
Today, despite the regularly arising interest in this “ideal nuclear reactor”, there is not a single project supported by financing to build at least a research facility. Only paper reactors are being developed, such as MOSART or MSFR or startup projects. However, the potential promise makes us carry out a variety of supporting studies (for example, on corrosion resistance) in the hope that someday progress in other areas (for example, in materials) will give impetus to the development of JSS.
Conclusion
If a persistent interest in atomic energy re-emerged in the world, the industry in the zagashniki has developments capable of solving many problems of sustainable supply of civilization with energy. However, in a situation where all the buns go to a renewable source, most likely for most of the promising concepts of reactors we will see only experimental plants and their leisurely development.
