Most of you have probably heard about the nuclear problem in Japan that recently came about because of the earthquake and tsunami that hit. However, the nuclear problem is not a direct link to either of these natural disasters. The reason Japan is having so many problems with the Fukushima Daiichi nuclear power plant is not because the plant suffered physical damage from the earthquake or tsunami but because the electrical power went out. This causes problems because the water levels in the reactors are very low and the fuel rods are unable to be kept cool and they are reaching dangerously high levels of temperature of about 5,000 degrees Fahrenheit. As a result, the zirconium casting that protects the fuel rods is melting. This is causing them to be exposed to the atmosphere which is causing radioactivity, specifically the decay of alpha, beta and gamma rays. Yes, these decays can be very harmful when coming in contact with cells of the human body and this will increase the chance of our cells becoming cancerous. Before we get to ahead of ourselves and go into details about theses decays we must first take a step back and talk about the basic physics behind these processes.
There are four main fundamental forces known that have effects on our world. These forces are gravitational forces, something which everyone should be the most familiar with since it is what keeps us on the ground and not floating in the air. The other three you may not be as familiar with even though all of us still come in contact with theses forces on a daily basis also. Electromagnetic forces deal with the attraction and repulsion of charges. Every substance is made up of charges, even you and I are made up of charges. There are only two types charges, positive and negative. Let us look at oxygen for example, since we should all be very familiar with oxygen because we use it every day to breathe. There are two main parts to an oxygen atom, the nucleus and the electron shell. The electron shell as you could probably guess is made up of electrons which carry a negative charge. The nucleus on the other hand, is made up of protons, which carry a positive charge, and neutrons which do not have a charge associated with them. A typical oxygen atom has the same number of negatively charged electrons as there are positively charged protons. Therefore, the overall charge of an oxygen atom would be zero since the negatives cancel out the positives. Now that we know a little more about charges let us get back to the electromagnetic force which deals with how charges react to one another. If two charges are the same, let us say we have two positive charges; they will try to get as far away from each other as possible. On the other hand, if we have a negative and a positive they are going to be attracted to each other. I guess this is why they say opposites attract! The last two fundamental forces are the strong and weak forces. These are the forces that we will be focusing on with our discussion about Japan. First, we will discuss the strong force. Like the name suggests it is the strongest of the four fundamental forces but particles have to be fairly close to feel the effects because it has a very small range. The strong force is what is holds our neutrons and protons together to make up the nucleus in our oxygen atom. However, in the larger atoms that have a lot of protons, extra energy is needed to keep them bound together. The weak force is what is responsible for the radioactive decay of subatomic particles. Again like the name suggests, it is weaker than the strong force and electromagnetic force and like the strong force it has a very limited range. Still most particles will decay because of a weak force over time. The weak force is mostly related to beta decays.
Now let us talk about how a nuclear reactor works and what exactly does it do. To put it simply, a nuclear reactor splits atoms and releases the energy that was used to keep their parts together. This occurs because of a process called nuclear fission. Even though the nucleus of an atom is held together by the strong force, you are still able to separate the protons and neutrons by throwing neutrons at the nucleus. The particles produced from the splitting causes a chain reaction of splitting atoms. Gamma decays are also a product of splitting atoms. In a reactor, the chain reactions are able to be controlled by the control rods which absorb some of the neutrons. In Japans case, the control rods are unable to be cooled and the chain reaction is unable to be controlled. The energy released by splitting atoms, heats water and produces steam which is used to turn turbines to generate electricity.
Now I believe we have covered enough background information that we can start taking about the alpha, beta, and gamma decays that the people in Japan are being exposed to and we will find out if we (here in the Midwest) have a chance of physically experiencing the effects of the decays and if we should do anything to prevent the damages that we know radiation can produce. An alpha decay is when a nucleus emits an alpha particle (two protons and two neutrons bound together) and therefore transforms into another atom. Let us keep relating this to our oxygen atom that we have gotten to know so well (even though alpha decays are more likely to occur in atoms with much larger numbers of protons and neutrons). A typical oxygen atom has eight protons, electrons and neutrons. If this oxygen atom were to undergo alpha decay and emit an alpha particle, the oxygen atom would be transformed into a carbon atom which has four electrons, protons and neutrons, and it could continue to emit alpha particle and therefore continue to change elements. Alpha decays are probably the most common out of the decays we will be talking about. If alpha decays were to reach our cell it would be very destructive, like a lawn mower which destroys everything in its path. On a higher note, alpha decays are very easy to protect yourself from. Most of the time, your clothing will prevent alpha decays from reaching your cells. In other words you should not be too worried about alpha decays as long as you take the right precaution.
Beta decays, like we had mentioned before, deal with the weak force. In this case, a beta particle is being emitted (an electron) while a neutron is being transformed into a proton. This changes the atom into another element. If a beta decay comes in contact with our cell it only destroys a small path through our cell in which it travels, like if you imagine a golf ball being putted on a green. The golf ball comes in very little contact with the entire green.
Gamma decay is when a nucleus changes from a higher energy state to lower energy state by means of electromagnetic radiation. Unlike alpha and beta decays there is no change in the number of protons and neutrons. Therefore, the parent and daughter atoms are the same element. However, a photon is emitted which is basically a ball of electromagnetic energy. Gamma decays are what you should be worried about since they cause the most damage out of the three types of decays to our cells. A gamma decay going though our cell is similar to a windy day. Unlike the alpha decay, it takes a lot more than a layer of clothing to be protected from gamma decays.
Finally getting to your main question, should we be worried about iodine decays here in the Midwest? My answer is no! First of all the distance between the Midwest and Japan is far too great. Those on the coast might get a very small portion but that distance is even too great. Secondly, the half life of iodine is only 8 days. This means that in 8 days only half of the amount of iodine is left. Since the destruction has happened over a month ago, there is very minimal amount of iodine. Therefore, there is no need to take iodine tablets because there no iodine in our atmosphere from the nuclear disaster in Japan. However, for the people in Japan, that is another story.
