Nuclear Bombs, Nuclear Energy, and Terrorism

Many observes believe that the most profound problem with using nuclear energy for electricity generation is the connection between nuclear power and nuclear weapons. In this view, the threat of nuclear weapons proliferation increases if the world relies on nuclear power, because nuclear power capabilities could be translated into nuclear weapons capabilities. The relative merits of renewable energy and nuclear fission energy (omitting fusion as still speculative) as eventual substitutes for fossil fuels are highly controversial, with unresolved arguments over relative economic costs, environmental impacts, practicality, and safety. However, the weapons connection is unique to nuclear fission energy and constitutes, for some people, a reason to limit or abandon it.

Giving up nuclear power would obviously avert the danger that nuclear power facilities might be diverted to weapons purposes. However, it would not avert all dangers of weapons development. It is quite possible to have nuclear weapons without nuclear power as well as nuclear power without nuclear weapons. In fact, most countries that have nuclear weapons had those weapons well before they had civilian nuclear power. Other countries that have made substantial use of nuclear power, such as Sweden and Canada, are rarely perceived to be potential nuclear weapons threats.

Nonetheless, a program in one area can aid a program in the other.

From David Bodansky’s Nuclear Energy (second edition), the beginning of two chapters examining these links. I will be summarizing these chapters over a number of posts, and providing some background. Obviously, you would get more detail reading the book!

Both nuclear power and nuclear weapons use U-235. Power reactors use lightly enriched uranium (LEU), natural uranium (0.7% U-235) enriched to 2 – 5% levels. Weapons grade has been enriched to 90%+ U-235. U-235 is the active ingredient in both not because it is more radioactive than the much more common isotope, U-238, but because U-235 plus a neutron does interesting stuff: it becomes U-236 which fissions, releasing lots of heat (the reason nuclear or fossil fuel or geothermal power is used) and lots of neutrons to continue the process. U-238 plus a neutron becomes U-239, which decays into Pu-239; this gives off very little heat and releases no neutrons.

Atomic bombs (using U-235 or Pu-239) depend on an explosion pushing together two sub-critical masses (not sufficient to provide chain reaction) to make a super-critical mass. With a super-critical mass, enough neutrons are generated fast enough to irradiate all of the U-235 atoms in a small fraction of a section.

The Hiroshima bomb used U-235. It killed perhaps 100,000 people immediately or within a few weeks, and had an energy yield equivalent to 15 thousand tons (kt) of TNT. The 21 kt Nagasaki bomb, using Pu-239, killed somewhat fewer people. Additionally, from 1950 – 1990, there have been 421 excess cancer deaths(above that expected). No genetic effects have been observed. [I heard several years ago that with improvements in bio-assays, a study was intended for Nagasaki victims to find otherwise undetectable genetic effects. I also heard that residents of Nagasaki were not lining up to participate. I don’t know whether the study was done and whether the results were positive or negative.]

Atom bomb victims receive treatment under a Red Cross flag on the outskirts of Nagasaki following the attack.

Atom bomb victims receive treatment under a Red Cross flag on the outskirts of Nagasaki following the attack.

Also in this series
Part 2 Today’s Bombs, Making a Bomb
Part 3 Making Bombs from Nuclear Waste
Part 4 Terrorist Targets
Part 5 Nuclear Proliferation—International Treaties
Part 6 The Bomb Spreads
Part 7 Nuclear Power and the Weapons Threat
Part 8 Wrapup on Nuclear Power Series

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