Physics

The Dangers of Radioactivity



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Radioactivity is dangerous to biological organisms and needs to be evaluated based on the frequency and magnitude of the exposure. There is always the point about doing a risk/benefit analysis but there seems to be some serious misunderstandings about what radioactivity actually is and how pervasive it is.

Radioactivity is the emission of energy in the form of particles and electromagnetic waves from unstable atomic nuclei. This means that there are some atoms which are basically unstable, and when they break down they will spontaneously emit particles or high energy electromagnetic waves. These high energy waves are in the frequency range of X-rays and gamma rays. Each type of emission from the atom is considered a part of radioactive radiation and depending on the type and energy will determine what risk is imparted to the biological organisms.

Particle emissions, such as alpha and beta particles, are readily stopped by most barriers so that clothing and skin are effective in protecting individuals from exposure. A more significant risk occurs should even low-level radioactive materials be ingested since the internal organs lack comparable protections.

Often the argument is made that many radiation sources are lower than normal background levels, but this is misleading. Background levels of radiation occur from the ambient environment and consequently represent an ongoing level of exposure, so additional radiation exposures need to be considered over and above those that are always present.

High energy electromagnetic waves are also present in the environment from radioactive particles and from external sources such as cosmic rays. Cosmic ray showers occur when high energy electromagnetic waves collide with particles in the atmosphere, they may cause a chain reaction that creates a cascade of high energy particles "showering" the earth.

The risk to biological organisms is that high energy particles or waves are not stopped by ordinary barriers, and as they pass through the body, there is a small but finite possibility of colliding with an atom or molecule within the body. Such a collision will tend to destroy the atom or molecule which would disrupt any process associated with it. In singular occurrences this is a trivial event; however when the number of interactions becomes large due to a significant radiation exposure then long term damage can occur. The longer the exposure, lethal levels can be reached resulting in death.

The argument is also advanced that nuclear energy poses minimal risks of exposure and especially regarding concerns about meltdowns or a Chernobyl type accident. However, the argument is less persuasive when we consider disposal of nuclear waste materials which will remain radioactive for thousands of years; Plutonium has a half-life of over 24,000 years. The net effect is that this waste material is cumulative and will be dangerous for longer than all of known human history. There is also no known means of energy production that isn't just simply adding to this stockpile of dangerous material.



While there are numerous assurances that this waste can be safely stored, the simple reality is that it can't. There is no construction material or process that human beings can exploit that can assure a reliable lifespan that approaches the times needed to protect against the materials being held. To protect against a half-life of 24,000 years is almost 6 times longer than the Great Pyramid has been in existence, which would still render half the material radioactive. Another 24,000 years is required to render another half of the material "safe".

Even using locations that are geographically isolated precludes consideration for the changes that could occur over the next several thousands of years regarding earthquakes, and other unanticipated problems. Since it would be impossible to guarantee that no leakage or breach could occur into ground waters, surrounding life forms, or the air over this period of thousands of years, we need real answers to these issues.

Every discussion of the dangers of radioactivity implies that a proper risk/benefit analysis will show the wisdom of using nuclear energy. The problem with this approach is that the benefits are always short-term, while the risks are under-rated since the impact extends, by definition, well beyond the life times of the situation being assessed. In short, a favorable risk/benefit analysis must conclude that we will derive the benefit, while future generations must absorb the risk.

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