How and where and when does man build a nuclear reactor that is safe and impacts the community in a minimal fashion?
The answer is simple, not simplistic, and derives from common sense and good old Yankee ingenuity.
A reactor must be built in a place where an eventual meltdown will not cause a horrendous calamity. Places that are safe exist. Because the longest-lived reactors in the world sit near a great body of water, water-cooled nuclear reactors must reside. In a meltdown, huge quantities of water cool the core and bring the reaction back to equilibrium. In the United States, safe places are on the seashore of coastal states and abutting the great lakes area where the lakes hold millions of gallons of extremely cold water, benefiting only the Erie Canal and Niagara falls.
A reactor can also be built in a remote area where a meltdown has no direct effect on local populations. In sparsely populated states in the northern forties of longitude. Here, a meltdown has little consequence and the energy produced by reactors can feed into a grid to serve populated cities and heavy industry factories.
The reality of meltdowns is that the core forms a superheated magma and sinks deep into the earth. Intervention by man serves no purpose and the core remnants can be fenced off until radiation follows the logarithmic law of extinction.
Reactor shielding
Most current nuclear reactors are poorly shielded because of man’s inhumanity to man. To shield a nuclear reactor, water serves to moderate small particles like quarks and bosons. The next shielding layer stops the most important aspect of nuclear radiation danger. Bromstrellung is a German word for radiation secondary to the deceleration of basic particles like protons, neutrons, and electrons. Bromstrellung registers in the gamma and x-ray region of ionizing radiation. To create bromstrellung, an alkaline earth crystallite like steel becomes an emitter of bromstrellung when the subatomic particles impact upon the nucleus of an atom and decelerate. Impacting particles generate gamma rays. A secondary shield of high mass number element like lead or other heavy metals, turns the bremsstrahlung into infrared radiation also known as heat by means of the photoelectric effect. In addition, to shield a nuclear reactor emanating fast neutrons, gamma rays, heat and light, three shields become necessary. The first is an ionic shield that can be made from water. The second is a braking radiation shield to be made from steel; the third is a gamma shield that fabricates from use of any of the heavy metals in the periodic table of elements. This coupled with calculation of radiation safe distance by means of a Geiger counter forms the parameters and specifics of shape and size of containing vessel. It is prudent at this point to remember the basics of nuclear physics: distance and shielding. The force of radiation = Gmm/rsquared where G is the acceleration due to gravity or the speed of light.
Breeder reactors
Breeder reactors are thorium breeders or uranium breeders. Thorium breeders are safer because the core does not go critical as fast as a uranium breeder fired by plutonium. The birth of uranium 235 or plutonium 239 by means of thorium or uranium breeders, respectively, occurs at a logarithmic rate. The product must be removed in relation to a logarithmic calculation based on breeding mass and size of the fissioning bed. The math is simple; people are complex and amiss to education and behavior change.
The rate of breeding is directly proportions from the rate of radiation emitted from a core. New material is added as the product is born and the reactor is safe and fashionable. In the event of a meltdown, non-reacted raw material pulls from the core and the reactor comes to rest. All reactors will eventually become breeder designs because the cost, difficulty, and danger of changing reactor core reactants is the same whether conventional or breeders. Conventional reactors need to change fuel rods more often.
Reactor design
A circle of concentric rods seems the safest and most logical picture of a reactor core. The rods are suspended by means of a chain or wire just as a guillotine blade hangs over the head of a criminal. If the core overheats, moderator rods can be inserted or the raw material can drop out of the core into a concrete tomb. The reactor sits safely away from supervising staff and controls occur by action of chains, wires, and levers pulled or guided from a remote location by robots. As in Chornobyl or Three Mile Island, all nuclear accidents result from human error; for this reason, and this reason only, all reactors, cores, and controls must be completely idiot proof.

Radioactive waste
Radioactive waste equals strontium ninety and cesium 137, along with radioactive water. Strontium 90 mainly emits alpha particles with a half-life of five thousand years, and cesium 137 emits gamma rays with a half-life of 120 days. In the future, man will collect radioactive waste as a positive byproduct of a nuclear reactor and use the waste as a source of heat or a source of electrons, forming batteries by means of the photoelectric effect, turning gamma into electron movement in a wire. Currently, the best way to store radioactive waste is to drop it into a chasm that empties into the center of the earth. Will radioactive waste become more valuable than gold when humankind uses it to bake long-term batteries?

Fission or Fusion Oh My!
Fission reactors tend to overheat and go critical. Fusion reactors burn at full throttle and can die in an instant. Fission reactors produce large amounts of gamma-generating waste, and fusion reactors generate helium which, when it accumulates, is one of the most toxic elements to biological life forms. The choice will be made by the next generation. The author, for one, chooses fission because fission reactors do not go out, they refuse to die. He excludes fusion because of the generation of huge amounts of helium and a tendency to blow out. This author feels that fusion reactors will only serve as power for military vehicles because they require less shielding. However, other dreamers with their hands in their hair, imagination, and a whim of Yahweh will choose in a scenario of beauty and optimism. We can dream, and in this want, dream even better. Puff on when the beer goes flat.