A Field Trip to Chernobyl - How Close is Too Close? Preview Close Preview

What is the Chernobyl Nuclear Disaster? (1/21)

On April 26, 1986, during a routine systems check, a power surge resulted in the meltdown of reactor #4 of the Chernobyl Nuclear Power Plant. The explosion and fire released radioactive material into the surrounding area (and as far away as other countries). The image below shows the building after the explosion.

Chernobyl Disaster (Photo Credit: New York Times)

The town built for the power plant workers, Pripyat, was only evacuated after several townspeople fell severely ill. Citizens were told to evacuate and only take what they needed for three days as they would soon return-- however, no one was allowed to return to their homes. The evacuation of Pripyat’s 43,000 residents took 3.5 hours, using 1,200 buses.
Chernobyl Evacuation (Photo Credits: Chernobyl Foundation)

To get a better feeling for what happened that day, check out one of the early news reports from ABC News: ABC News Report, April 26, 1986

The town looks like a modern day ghost town with objects in the same spot as they were on April 26, 1986. Take a look at photos taken from 2011.

This radioactive area, known now as the "exclusion zone", has recently been opened to tourists. The question you are going to consider (maybe not fully answer, but consider) with this lab, "Would you take a field trip to Chernobyl?" Is it safe to visit Cheronobyl? Is it safe to be around radioactive material? Is there a "safe enough" distance to be from radioactive material? How close is too close?

Voice your opinion: would you want to go to Chernobyl?

What are the Chernobyl Tours Like? (2/21)

A simple Google search will bring you to many different tour companies operating today in Chernobyl: Chernobyl Tours. Play around on the sites and see what they say about the radiation. At some point, check out the Chernobyl Tour Guide Association’s Safety Rules found at The Chernobyl Tour Guide Association Rules.

There are a couple rules we want to highlight and use in our investigation today. Namely,
Stay on roads, the radiation levels on areas covered by vegetation are significantly higher. Even more important, the risk for contamination when walking amongst vegetation is higher because it is more difficult to avoid touching or inhaling anything. Radiation ends when you leave the place, but you don't want radioactive elements inside your body.

**When visiting the Chernobyl exclusion zone all visitors are obliged to:a.) Use clothes and shoes, maximally protect body, head, hands and feet;d.) Move around only according to the prescribed routes;

During the visit to the Chernobyl exclusion zone it is totally prohibited to:• Have a meal and smoke in the open air;• Touch any structures or vegetation;• Gather, use and bring from the Chernobyl exclusion zone any vegetables and cattle breeding products**

Why are these the rules? Why are regular clothes allowed—don’t tour participants need huge full-body coverage suits? Why can’t you go off the routes? What would happen if you went off the route? Why can't you eat in the open air? Why can’t you touch plants or vegetation? Why can’t you gather living organisms? These are weird, perplexing rules! To help us think about these, we need to know more about radiation and radioactive material.

Why do YOU think you are allowed to wear regular clothes instead of a full protective suit?

Why do YOU think you are not allowed off the routes?

Why do YOU think you are not allowed to pick up plants or living organisms?

The Science of Atoms, Part One: Elements are Specific Kinds of Atoms (3/21)

In order to determine if you would visit Chernobyl, you first need to know more about the science behind atoms, radioactivity, and different forms of radioactive decay. At the end of each section, there are questions to make sure you understand the ideas you just learned. We begin first with a tutorial on the structure of atoms.

The Science of Atoms, Part One: Elements are Specific Types of Atoms
Everything on earth is made up of different combinations and arrangements of specific kinds of atoms called elements. If you are wearing a cotton T-shirt-- you are surrounded by arrangements of the elements carbon, hydrogen, and oxygen. You are taking air into your lungs which consists of the elements nitrogen, carbon, argon, and of course, oxygen. You might have gotten to school in a car or bus which has a steel frame which could be composed of iron, titanium, calcium, oxygen, aluminum, and carbon. All of these are specific kinds of atoms called elements.

What determines what element an atom will be? What makes carbon... carbon? What makes hydrogen... hydrogen? The answer is found in the number of small, subatomic particles called protons found in the nucleus. It seems crazy to think about but the difference between hydrogen (a highly flammable, reactive gas) and helium (a very non-reactive, non-flammable gas) is only one proton; in the nucleus of every hydrogen atom is only one proton whereas every helium atom has two protons in its nucleus. The number of protons in an atom determines what kind of atom it is and therefore what properties the element will exhibit. Thus, elements are specific kinds of atoms that are determined by their unchanging number of protons (or positive charges).

Below is an image of the periodic table of elements, a table that lists all known elements on earth (both naturally occurring and man-made) and tells us a great deal of information on each. The placement/location of an element on the periodic table tells how it will interact with other elements and is incredibly helpful at helping scientists make predictions about the physical world.

Periodic Table of Elements

Click here for an interactive periodic table you can see better.

What kind of information is on the periodic table? Each square of the periodic table tells us the name of the element, how many protons are in the element, and the weighted average mass of each atom.


Let's look at an example. Every single calcium atom has 20 protons. Having 20 protons makes an atom calcium. Any atom with 20 protons will act like and have properties of calcium. Below, you will see an enlarged image of the information found about calcium on the periodic table. It is atomic number 20 (meaning it has 20 protons), its symbol is Ca, its name is calcium, and the average mass of each atom is 40.078 amu (atomic mass unit).


Imagine you picked an atom out of a bucket that had 7 protons (this is impossible to do, but pretend you can). Look at the Interactive Periodic Table . Determine what element or type of atom would it be? If you answered nitrogen, you would be correct.

Let's try some questions to make sure you've got it! Be sure to have a copy of the periodic table or open the Interactive Periodic Table to answer the questions.

What element has 8 protons?

What element has 6 protons?

You find an atom with 19 protons. What element is it?

If a scientist were able to add a proton to oxygen, what element would that atom now be?

Any atom with with 26 protons will act like and have properties of what element?

Elements are specific kinds of atoms that are determined by their unchanging number of _______________________.

In your research on Chernobyl, we will be talking about strontium. What is the atomic number of, or number of protons found in, strontium?

In your research on Chernobyl, we will be talking about helium. What is the atomic number of, or number of protons found in, helium?

The Science of Atoms, Part Two: Inside an Atom (4/21)

What are the parts of an atom? You have learned that elements are specific kinds of atoms based on the number of protons in their nucleus. We want to make sure you understand what this means and know a little more about the subatomic particles that make up an atom.

Protons are not the only kind of subatomic particle in an atom. In the most simple model of an atom, an atom is made up of 3 different subatomic particles: protons, neutrons, and electrons.

  • A proton is a particle that usually stays inside the nucleus and has a positive (+) charge.
  • A neutron is a particle that usually stays inside the nucleus and has a neutral (0) charge.
  • An electron is a particle that moves around the nucleus in an electron cloud and has a negative (-) charge.

Protons and neutrons are contained in the nucleus of an atom, the very dense center of an atom, and make up the mass of the atom. The strong nuclear interaction provides the primary force that holds nuclei together.
Atomic structure

Electrons are found around the nucleus in what are called electron clouds. While we often use models or pictures of atoms with "orbitals"-- these are not actually what atoms look like. These models or pictures can be very helpful for thinking about energy levels-- but we did not want you thinking electrons naturally float on discrete orbitals after doing this lab. The image below illustrates this difference.

Image on the right is a helpful model, but the image on the right is more scientifically accurate image of an atom.

Click here for a the Ted Education video, Jon Bergmann's Just How Small Is An Atom?, for a visual of the atom and its size.

Extension #1: Using the Interactive Table to learn about isotopesFrom the periodic table of elements, you can read how many protons are in an atom, this is the atomic number. From the interactive periodic table, you can click on the "isotopes" tab at the tab and then click on an element. You will notice that now the periodic table lists many different masses for the element. That is because an isotope of an element is one that has a different number of neutrons. For example, carbon has 3 different isotopes. Carbon will always have 6 protons-- that is what makes it carbon. However, it can have different numbers of neutrons which change the mass of the atom. It can have a mass of 12 (which contains 6 neutrons), a mass of 13 (which contains 7 neutrons), a mass of 14 (which contains 8 neutrons). The mass you see listed on the periodic table of elements is a weighted average which is not only a straight average of the masses but weights which isotope is most likely found on earth. This is why you see on the regular periodic table the weighted atomic mass of carbon is 12.011. Carbon-12 (carbon with 6 protons and 6 neutrons) makes up 98% of all carbon on earth so we "weight" that mass more.

Extension #2: Using the Jefferson Lab Site to learn about quarks and gluonsThese are very basic ideas of the subatomic particles in an atom. You may have heard on the news about quarks and gluons and are trying to figure out how those fit into the structure of an atom. If you would like to learn more about the subatomic particles in atoms, check out the Atom Tour through the Jefferson National Accelerator Lab . Additionally, you may have heard about how identical elements can weigh more or less based on the number of neutrons they have; these are called isotopes and you can read more about them here.

What is the charge on a proton?

What is the charge on a neutron?

What is the charge on an electron?

What two subatomic particles make up the nucleus?

The Science of Atoms, Part Three: Ionizing and Non-Ionizing Radiation (5/21)

So what is radiation, really? Let's learn a little bit more about what radiation is so we can better understand when and how it affects our health and possibly our decision to enter Chernobyl.

Radiation can be defined as "energy that travels through space either as electromagnetic waves or as moving subatomic particles." The amount of energy these waves contain falls along a spectrum where the shorter the wavelength, the more energy carried by the wave.


For a better resolution picture of this picture, click here.

A more in-depth look at the electromagnetic spectrum can be found here:

Radiation can generally be classified into two types: non-ionizing and ionizing.

Some radiation has very long wavelengths and is not considered dangerous to humans. This non-iodizing radiation is a part of our every day lives. For purposes of our discussion of Chernobyl, on the other hand, we will be looking at how some radiation has very short wavelengths and can be harmful to humans (these waves are called ionizing radiation).


For a better resolution picture of this picture, click here.

Non-Ionizing Radiation is radiation that has enough energy to move around atoms in a molecule or cause them to vibrate, but not enough to remove electrons or break the chemical bonds. The vibrations in the molecule can cause an increase in the temperature. Examples of this kind of radiation include visible light, radiowaves (including those used in cell phones) and microwaves.

Ionizing Radiation has enough energy to break chemical bonds in molecules, or remove tightly bound electrons from atoms, which creates charged molecules or atoms (ions). When this ionization happens, it releases energy that is absorbed by material surrounding the ionized atom. This is the type of radiation that people usually think of as 'radiation' and can be mildly to severely harmful to living organism. However, humans take advantage of its properties and fast wavelengths to generate electric power, to kill cancer cells, and in many manufacturing processes.

The image below shows that waves of lower frequency are classified as non-ionizing radiation and waves of higher frequency are classified as ionizing radiation. Note: the image is the reverse of the image in the video you just watched with non-ionizing radiation on the left and ionizing radiation on the right (don't get mixed up!).

Non-ionizing vs. ionizing radiation

For a better resolution image of this picture click here.

Radiowaves and microwaves are ________________ and ________________compared to gamma rays

What type of radiation, ionizing or non-ionizing, causes potential damage to humans?

A friend tells you that microwaves are a form of radiation. Is your friend correct?

When you use a microwave, what is the effect of the microwave oven on your food?

The Science of Atoms, Part Four: Alpha, Beta, and Gamma Rays (6/21)

The Science of Atoms, Part Four: Alpha, Beta, and Gamma Rays

Radiation and radioactivity are often confused. The Environmental Protection Agency defines radiation as "energy that travels in the form of waves or high speed particles" and radioactivity as a "property of some atoms that causes them to spontaneously give off energy as particles or rays. Radioactive atoms emit ionizing radiation when they decay." In our last section, we talked about radiation-- a term generally used to describe movement of energy. Now we focus radioactivity-- the specific kind of energy that comes from unstable nuclei of certain kinds of elements.

Atoms found in nature are either stable or unstable. An atom is stable if the forces among the particles that make up the nucleus are balanced. An atom is unstable (radioactive) if these forces are unbalanced if the nucleus has an excess of internal energy. Unstable atoms are called radionuclides. The instability of a radionuclide's nucleus may result from an excess of either neutrons or protons. An unstable nucleus will continually vibrate and contort and, sooner or later, attempt to reach stability by some combination of means:- ejecting neutrons, and protons (alpha decay)- converting one to the other with the ejection of a beta particle or positron (beta decay)- the release of additional energy by photon (i.e., gamma ray) emission (gamma decay). (EPA, 2015)

Nuclear Decay as Ionizing Radiation
According to Phys.Org, Radioactivity is the term given to the breaking-up (decay) or rearrangement of an atom's nucleus. Decay occurs naturally and spontaneously to unstable nuclei. Different forms of ionizing radiation may be emitted from an unstable radioactive nucleus. Energy is released and a new, more stable nucleus is formed. Some elements have unstable nuclei and will naturally release energy (in the form of an alpha particle, beta particle, or gamma ray) to become more stable.

Again from Phys.Org, Radioactive decay can occur in several ways, with the more common ones being:
Alpha Decay: the original, unstable nucleus releases an alpha particle (a helium-4 nucleus) consisting of two neutrons and two protons and results in a new element with a more stable nucleus.
Image of Alpha DecayFor a better resolution picture of this image, click [here](http://www.atnf.csiro.au/outreach//education/senior/cosmicengine/images/sun/alphadecay.gif).

Beta Decay: the original, unstable nucleus ejects an electron (or a beta particle) resulting in a new element that is more stable. The daughter nucleus thus formed has the same mass number of 234 as the parent but is one higher in atomic number as the decaying neutron has changed into a proton which is retained within the nucleus. Note: this is not the same as an electron being removed from orbitals around the nucleus.
Image of Beta DecayFor a better resolution picture of this image, click here.

Gamma Decay: the protons and neutrons within the nucleus rearrange into a more stable form, and energy is emitted as a gamma ray. In this case, the original unstable atom remains the same element, but with a more stable nuclear energy.

Image of Gamma DecayFor a better resolution picture of this image, click here.

Alpha and beta decay are all accompanied by the release of a particle and it is this particle that is the radiation associated with radioactivity. In the case of gamma decay, it is the gamma ray that is the "radiation" associated with radioactivity. Here is a summarizing image of alpha, beta, and gamma decay: http://www.energyweb.cz/web/rao/images/701.jpg

Learn more about these different types of radiation in the following video,

What results from alpha decay?

What results from beta decay?

What results from gamma decay?

The Science of Atoms, Part Five: Radiation at Chernobyl (7/21)

Source for Strontium-90 information: http://www.epa.gov/radiation/radionuclides/strontium.html
Strontium-90 is a by-product of the fission of uranium and plutonium in nuclear reactors, and in nuclear weapons. Strontium-90 is found in waste from nuclear reactors. It can also contaminate reactor parts and fluids. Large amounts of Sr-90 were produced during atmospheric nuclear weapons tests conducted in the 1950s and 1960s and dispersed worldwide.

![Decay of Uranium resulting in strontium-90](hereFor a better resolution picture of this image, click .

Strontium-90 emits a beta particle with, no gamma radiation, as it decays to yttrium-90 (also a beta-emitter). Strontium-90 has a half-life of 29.1 years. It behaves chemically much like calcium, and therefore tends to concentrate in the bones and teeth.

Strontium-90 is also found in waste from nuclear reactors. It is considered one of the more hazardous constituents of nuclear wastes. The accident at the Chernobyl nuclear power plant also introduced a large amount of Sr-90 into the environment. A large part of the Sr-90 was deposited in the Soviet Republics. The rest was dispersed as fallout over Northern Europe and worldwide. No significant amount of stronium-90 reached the U.S.

As strontium-90 decays, it releases radiation and forms yttrium-90 (Y-90), which in turn decays to stable zirconium. The half-life of Sr-90 is 29.1 years, and that of Yttrium-90 is 64 hours. Sr-90 emits moderate energy beta particles, and Y-90 emits very strong (energetic) beta particles.


The decay of strontium-90 results in what kind of radioactivity?

Does the decay of strontium-90 result in gamma decay?

The Science of Atoms, Part Six: Reducing Ionizing Radiation (8/21)

The nuclear reactor meltdown at Chernobyl was catastrophic. Fortunately, the impact of radioactive material can be reduced by time, distance from the radioactive material, and with the use of barriers. http://www.nrc.gov/images/about-nrc/radiation/time-distance-shielding.gif

Time: Individuals should limit the amount of time they are exposed to radioactive material. For example, during the clean-up of Chernobyl, soldiers were only allowed on the roof for 40 seconds at a time.

Distance: While much of Europe was impacted by the radioactive material in the air, the United States was spared from much of it because we were much farther away from the power plant. The "Exclusion Zone" is the 1,000 square miles surrounding the power plant where people should not enter for long periods of time.

Blocking: Damaging ionizing radiation can be blocked. Based on the kind of nuclear decay, different materials can block the radioactivity. Below is a diagram showing examples of how alpha, beta, and gamma radiation are blocked by different materials:


In the short video below, you would see how alpha, beta, and gamma radiation can be blocked by different sources.

You have have experienced this already. Consider when you get an x-ray and the technician, nurse, doctor, or radiologist puts a lead blanket over you to protect you. That lead blanket would protect you from alpha particles, beta particles, all the way up on the electromagnetic spectrum to gamma rays. If you look at the image above, you will know why: x-rays and even gamma rays cannot cross through lead.

What material(s) could you use to block alpha particles?

What material(s) could you use to block alpha particles?

What material(s) could you use to block beta particles?

What material(s) could you use to block beta particles?

What material(s) could you use to block gamma rays?