Enrico Fermi Nuclear Generating Station, Unit 2 This post originally appeared at 24/7 Wall St.

The anniversary of the Japan earthquake, which killed over 16,000 people and caused the disaster at the Fukushima Daiichi nuclear power plant, is only two weeks away.

Immediately after the disaster, several European nations decided to significantly trim their use of nuclear power.

Similarly, the Obama Administration decided to partially pull back from a previous move aimed at gaining more U.S. energy independence through the use of nuclear reactors.

Despite these decisions, nuclear energy remains the world’s most used source of emission-free energy source. This is particularly true in regions which are densely populated, although it is not entirely clear why.

Only one U.S. plant has been approved since the disaster — Southern Co.’s two reactors at Plant Vogtle site in Georgia. In fact, it is the first nuclear power plant approved in the U.S. in more than three decades. Yet, some U.S. states rely heavily on nuclear energy for generation of electric power, especially as a source of emission-free energy.

Nuclear energy cannot be readily replaced without having a river or huge lake for generating hydro power, without building huge wind farms, and as solar energy is years away. 24/7 Wall St. reviewed the ten states that rely heavily on nuclear power as their source of emission-free energy.

If clean energy is the wave of the future, then it’s time for the U.S. to expand on the 104 nuclear plants currently in operation. The push for nuclear power is in hope of producing cheaper electricity without producing air pollutants or greenhouse gases.

Safety is a big concern. Since the 1979 Three Mile Island meltdown, there has been no new construction of nuclear power plants and the Japan earthquake has bolstered recent arguments against more plants.

Currently, 31 of the states have nuclear plants. 24/7 Wall St.’s analysis covers the 10 states in which nuclear energy is the most significant source, or even the only source of emission-free power. In most of these states, the amount of total electricity generated by nuclear is above a third.

24/7 found that these ten states tend to have energy costs per capita above the national average. However, they also tend to be among the most densely populated states, which provokes the “not in my backyard” argument against nuclear power plant construction.

It also questions the usefulness of nuclear power as an alternative to less densely populated states that already have low electric cost per capita, such as North Dakota, Kentucky, Oklahoma, and West Virginia. Coal and gas power are plentiful in these states, which is an advantage, at least until fossil fuel supplies begin to run low.

24/7 Wall St. looked at the ten states that have the highest portion — 95% to 100% — of emission-free power from nuclear power plants using information from the Nuclear Energy Institute. We also looked at population density based on U.S. Census Bureau numbers. U.S. Energy Information Administration provided the number of plants per state.