“In evaluating the safety, economic feasibility, net energy yield, and overall environmental impact of nuclear power, energy experts and economists caution us to look at the entire nuclear fuel cycle, not just the power plant operations. A nuclear fuel cycle is: the mining of uranium, processing and enriching the uranium to make fuel, using it in a reactor, and safely storing the resulting highly radioactive wastes for thousands of years (10,000-240,000) until their radioactivity falls to safe levels.

(Therefore, when the entire nuclear fuel cycle (including safely storing the nuclear wastes) is analyzed there is a very small, to zero, net energy yield.)

Note: according to a Nevada state agency report, 10 years after being removed from a reactor, a spent-fuel assembly would still emit enough radiation to kill a person standing 39 inches away in less than 3 minutes.

Bottom line:  After almost 60 years of research, there is no consensus on how to store growing amounts of radioactive wastes safely for thousands of years.

Not to mention: The United States and 14 other countries have been selling nuclear reactors and uranium fuel enrichment technology in the international marketplace for decades. Much of this information and equipment can be used to produce material for use in nuclear weapons. This is one reason that 60 countries—1 of every 3 in the world—now have nuclear weapons or the knowledge and ability to build them” (Miller and Spoolman, p. 309-317).

In addition, the government gives the nuclear power industry subsidies, tax breaks, insurance (which is very costly), and loan guarantees—without which nuclear power wouldn’t be affordable. Q:Where does the government to get their money for these “perverse subsidies” ?
A:The taxpayers

Miller, G. T. and S. E. Spoolman (2010). Environmental Science. 13th Edition. Belmont, CA, Brooks/Cole, p. 309-317.

The low net energy yield is the reality, when the entire nuclear fuel cycle is accounted for…

LWR’s (light-water reactors) are highly inefficient, losing about 75% of the energy available in their nuclear fuel as waste heat to the environment, just in generating electricity. Before that point, 9% of the energy content of the fuel is lost when the fuel is mined, upgraded, and transported to the plant. At least another 8% is lost in dealing with the radioactive wastes produced by the plant, bringing the net energy loss to about 92%. If we add the enormous amount of energy needed to dismantle a plant at the end of its life and store it’s highly radioactive materials for thousands of years, some scientists estimate that using nuclear power will eventually require more energy than it will ever produce.

(from my 2010 Environmental Science texbook, by Miller and Spoolman)