The sun's nuclear reactions are fusion reactions at extremely high temperatures and pressures, while the nuclear reactor's nuclear reactions are fission reactions at typical temperatures and pressures for earth.
In the reactor core, which is the volume filled with the fuel assemblies
Within the reactor core of a nuclear power plant all the actions and reactions take place. These reactions release energy in the form of heat. This can be harnessed to provide power to the building.
Nuclear fission takes place in the nuclear fuel rods that are placed in the reactor core that is situated in the reactor pressure vessel. The reactor pressure vessel is usually situated inside the reactor containment.
This answer can not be accurately answered without first knowing what type of nuclear reactor it is. A pressurized-water nuclear reactor is probably the most common so I'll briefly talk about some factors that affect the number of chain reactions in that type of nuclear reactor. First of all, the temperature of the water entering the reactor core will affect the number of chain reactions. The colder the water, the greater the number of reactions. This is primarily because the colder water is more dense and thus releases more neutrons which speeds up the chain reaction rate. Of course, reactor operators, wishing to control the number of chain reactions in order to make the reactor stable may raise or lower "rods" which will be made of a material that tends to absorb neutrons and thus lowering the chain reaction rate. These are the two most common factors affecting chain reaction rate. Would delve further into this question but it gets rather complicated at this point.
The sun's nuclear reactions are fusion reactions at extremely high temperatures and pressures, while the nuclear reactor's nuclear reactions are fission reactions at typical temperatures and pressures for earth.
In the core of a nuclear reactor
the suns nuclear reactions happen at extreme temperatures we do it at lower temps
In a fission reactor, control is implemented by inserting control rods into the reactor. These are made of a material that absorbs neutrons, and prevents a reaction from taking place.
In the reactor core, which is the volume filled with the fuel assemblies
Nuclear fission, not to be confused with fusion.
The core of the reactor contains the nuclear fuel. Having a moderator in place within the core ensures that the nuclear fuel is processed at an accurate time duration. This can prevent serious problems from occurring within the entire nuclear reactor.
The #4 reactor is the reactor at the Chernobyl Nuclear Power Plant (Pripyat, Ukraine) that exploded on April 26, 1986. It is still the worst nuclear accident to ever take place anywhere.
No place, we have not yet determined how to make a fusion reactor. Only fusion bombs.
Within the reactor core of a nuclear power plant all the actions and reactions take place. These reactions release energy in the form of heat. This can be harnessed to provide power to the building.
Nuclear fission takes place in the nuclear fuel rods that are placed in the reactor core that is situated in the reactor pressure vessel. The reactor pressure vessel is usually situated inside the reactor containment.
Those reactions that take place in functioning nuclear reactors (i.e not Chernobyl or Fukushima when the accidents happened).