Next Generation Nuclear Power

What is Generation-IV nuclear power?

Generation-IV nuclear power implies a series of nuclear reactors and fuel cycle facilities that can be used to manage the difficulties and risks associated with the methods that are already in use. The requirements imposed on generation-IV imply that the system of reactors should produce more fuel than is consumed, while also destroying the long-lived elements created in the reactor during operation.

Generation-IV are next-generation systems to be designed and built by two decades from now. Currently, we use Generation-III nuclear reactors which is a development of generation-II with improved fuel efficiency, operation time and safety measures.

What are the benefits of using Generation-IV nuclear power?

  1. It can replace fossil fuels – Nuclear power generation does not involve emission of CO2 and other greenhouse gases and so it has direct benefits to the environment.
  2. It is safer – Accidents like Chernobyl can be avoided by using fourth-generation nuclear power as it lessens the possibility of significant damage during the accidents, and also minimizes the potential consequences of any accidents that do occur.
  3. Nuclear fuel can be recycled – Recycling helps to minimize the production of nuclear waste and it helps in recovering most of the energy contained in uranium. It is performed using PUREX (plutonium uranium extraction) process and researchers are working to develop more effective recyclable technologies. 
  4. Weapon production is not possible from it – In Generation IV, it will be assured that uranium and plutonium are never separated thus making the quality of nuclear material very poor to serve as a weapons material, but good enough for fuelling a reactor. 

Some other advantages are it is cost-effective, 100-300 times more energy yield, ensures nonproliferation, etc. 

What are the general classes of reactors that can be used for Generation-IV?

  1. Gas-cooled reactors – These reactors use gas as a core coolant (usually He or CO2). One of the examples is the pebble-bed reactor. Its design is based on a pebble, a billiard-ball-size graphite sphere containing about 15,000 uranium oxide particles with the diameter of poppy seeds. One of the layers, composed of tough silicon carbide ceramic, serves as a pressure vessel to retain the products of nuclear fission during reactor operation or accidental temperature excursions. Heat resistant refractory materials are used so that reactors can work at higher temperatures.
  2. Water-cooled reactors –  Even the standard technology of water-cooled nuclear reactors has a new look for the future. In order to overcome the possibility of accidents resulting from the loss of refrigerant (which occurred on Three Mile Island) and simplify the plant in general, a new class of Generation IV systems has emerged in which all primary components are contained in a single bowl. Placing the entire refrigerant system inside a pressure-resistant container means that the primary system cannot suffer a significant loss of refrigerant even if one of its large pipes breaks. The smaller core and lower refrigerant density reduce the volume of water that must be stored in the containment in the event of an accident.
  3. Fast-spectrum – Also known as ‘High-energy neutron reactor’, they generally use liquid sodium as the coolant. Future versions of this can utilize sodium, lead, a lead-bismuth alloy or inert gases such as helium or carbon dioxide.  The higher-energy neutrons in a fast reactor can be used to make new fuel or to destroy long-lived wastes from thermal reactors and plutonium from dismantled weapons. By recycling the fuel, they can deliver much more energy from uranium while reducing the amount of waste that must be disposed of for the long term.
  4. Nuclear Power Primer – Mostly they are pressurized water reactors. Water placed under high pressure to suppress boiling serves as both the coolant and the working fluid. Slow neutrons emitting during the nuclear fission reaction are absorbed by the control rods and then they are raised out of or lowered into the core to control the rate of the nuclear reaction.

Generation-IV nuclear reactors are designed to overcome the weaknesses associated with existing nuclear reactors. The implementation of the system will occur step wise. Such large projects require strong political supports also. To start with, a few reactors will be commissioned and the fuel cycle facilities will have low capacity. It is not certain that the first reactors will fulfill all the requirements but it is certain that this generation will be better than any other existing energy source. 

References:
https://www.scientificamerican.com/article/next-generation-nuclear/
https://onlinelibrary.wiley.com/doi/abs/10.1002/er.4683

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