Blinded by Science blog 10: Is nuclear energy dangerous?

Whoops!  It has been awhile.  Sorry!  I was partway through this blog post when I got a new job that required me move to a different state.  A new job writing scripts for online science tutorials.  In other words, I got hired to basically do what I started this blog to practice doing: communicating science.  As such, I let the blog fall by the wayside for the past few months.  After having a couple people tell me they liked reading the blog and I should get back to writing it (which is a couple more people than what I thought read the blog), I’ve decided to get back to writing (I hope).

Anyway, for this post, Christian S. asks, “Is nuclear energy dangerous?”

Courtesy Archive.org

Yes.

But then again, lots of things can be dangerous.  Driving cars can be dangerous.  Peanut butter can be dangerous.  Even stairs can be dangerous (especially after leg day).

Or if you are Charles Xavier.

But being dangerous doesn’t mean that something is bad or worthless.  It comes down to, do the benefits outweigh the possible harms?  So with today’s blog entry, I’m going to start off describing what nuclear energy is followed by how nuclear energy is dangerous (actually answering the question asked).  Finally I will talk about the benefits of nuclear energy.

So what is nuclear energy?

As I’m sure we all remember from science class, atoms are the smallest unit of matter that still has properties of an element.  All atoms, no matter which element, are made up of smaller particles called protons, neutrons, and electrons (which are made up of even smaller particles that I’m not going to go into because that’s a confusing rabbit hole I’ll most likely get lost in).  The dense core of the atom, the nucleus, is made up of protons and neutrons and electrons orbit around it.  Each atom of an element has a specific number of protons in its nucleus, so an atom that has 8 protons in the nucleus has completely different properties from an atom that has 9 protons in its nucleus (8 protons is oxygen while 9 protons is fluorine).  It is possible for a nucleus of a specific atom to have a different number of neutrons as another nucleus of the same type of atom.  Atoms that have the same number of protons but different numbers of neutrons are called isotopes.  As the number of protons and neutrons in a nucleus increases (most number of protons in an element discovered so far is 118 in the element Ununoctium), some elements become unstable and can break down.  When this happens, they release protons and neutrons from their nucleus in an effort to become more stable while also releasing energy.  This is known as radioactive decay.

Nuclear power plants use the process of nuclear fission to produce electricity.  In simplistic terms, nuclear power reactors would shoot a neutron into the nucleus of an atom of some fissionable material (such as uranium) which is unable to stably absorb the neutron.  The nucleus then splits into smaller fragments, which also releases energy, radiation, and more neutrons.  These neutrons can hit other uranium atoms causing them to split as well, releasing more energy, radiation, and neutrons which can hit other atoms.  This chain reaction can continue with no further outside involvement until all the fissionable material has been used up.  However, nuclear power reactors control the chain reaction through a variety of processes such as the use of materials that can stably absorb neutrons (the fewer neutrons flying around, the more controlled and slower the reaction progresses).

The energy released during fission heats water to create steam.  The steam is used to spin a turbine that produces electricity.

Dangers:

Before I begin talking about the dangers associated with nuclear energy, I will mention a danger NOT associated with nuclear energy, an explosion like a nuclear bomb.  It is impossible for a nuclear power plant to explode like a nuclear bomb (Truth #2).  Nuclear plants do not use uranium that is enriched enough.

That said, there is always a chance that an accident could occur at a nuclear power plant.  The worst type of accident is a meltdown, where the core of the reactor gets too hot and the fuel cracks, releasing radioactive gas; or the hot, radioactive material melts and damages the protective structures so it can reach the environment.

In the event of a nuclear power plant accident, danger exists from the plume of radioactive material that may be released and contaminate people and things that are outdoors, from radioactive material that is ingested or breathed in, or from radiation exposure to those living nearby the power plant.  Radiation can damage the DNA in the cells of the body, either causing mutations or the death of the cells.  If a high enough dose of radiation is received all at once, death occurs due to cellular death and organ damage.  Lower levels of radiation exposure can cause genetic mutations that could lead to cancer, even years later.  Even a relatively minor incident in which radioactive material leaks into the environment could cause health problems or environmental damage.*

The chances of an accident occurring are very small, however.  Reactors are designed with multiple layers of protection and redundancies to make the chance of an incident occurring very small.  In fact, a type of incident like the one that occurred in Chernobyl could not occur here in the United States because that type of reactor was never built here (Truth #7).

And just as a nice visual aid to illustrate the difficulty of the public being exposed to high levels of radiation (plus I love the source), here’s how safe you would be swimming in the pool used to store spent nuclear fuel rods until they were safe for transport.  Really makes you think, though that whole lead poisoning thing at the end means you shouldn’t try it.

*It all depends on the dose of radiation you receive and how often you receive it.  Humans are exposed to numerous sources of radiation in their everyday lives (1, 2).  In fact, you absorb slightly more radiation from eating a single banana than you do from living within 50 miles of a nuclear power plant for one year.  Our body is usually able to repair the damage caused by this low level of radiation.

Benefits:

One of the major benefits of nuclear energy is a lack of air pollution production or carbon dioxide release.  You could easily make the argument that the type of pollution that would occur if a nuclear incident occurred is more damaging to the environment and human health than the air pollution and carbon dioxide release of traditional power plants, but it comes down to the difference between a potential harm vs a guaranteed and currently occurring harm.

Also, the “energy density” of uranium (and other nuclear energy material) is greater than that of coal, oil or natural gas.  In other words, if you have a pound of uranium vs a pound of coal, the energy that you could harvest from the uranium is many times greater than what you could harvest from the coal.  Nuclear power could thus reduce our dependence on fossil fuels, and specifically reduce our dependence on foreign oil.  Additionally, the cost of producing energy via nuclear power is lower than the cost of producing energy with fossil fuels.

And just as an aside, it is interesting to note that in the 50+ years of commercial nuclear power, there has been no radiation-related health events in the public linked to the operation of nuclear power plants.

So Christian, to answer your question, there are dangers involved with nuclear energy, but those dangers are taken into account in the design of reactors and the risk of something bad happening is very small.

Blinded by Science blog 9: How are Monarch Butterflies faring as a species?

Today’s blog post deals with a topic near and dear to all our hearts . . . bugs.  I know it is a topic that should lend itself to calm and quality discussion.

Or not.

Fine, we’ll focus on a cute, non-threatening insect.

You are not any of those three things.

I was talking about monarch butterflies.  Those pretty critters we all learned about in school.

See . . . it is cute, non-threatening and an insect.

Monarch butterflies are one of the most recognizable insects in North America with a very distinct orange and black pattern.  The butterfly has a four stage life-cycle: egg, larva, pupa, and adult.  Monarchs are a migratory species of butterfly, traveling in the fall from southern Canada and the northern United States to Mexico, a trip that is roughly 1,200 to 2,800 miles.  But over the last 20 years, monarch populations have decreased by about 90 percent.  And this leads us to today’s question.

Steve P. asks, “I know Monarch Butterfly populations have taken a big hit in the last few years.  What is the latest update?  What are the theories/reasons behind their decline?  Is there any hope that a sustainable population can be maintained?”

The biggest reason for the decline in Monarch population is habitat destruction in both Mexico and the United States.  In Mexico, to combat deforestation, the government in 1980 designated 56,000 hectacres of land as a wildlife refuge.  This refuge has since been called the Monarch Butterfly Biosphere Reserve and is now a UNESCO World Heritage Site.  Unfortunately illegal logging is still a problem.  Additionally, the land is also the home of multiple indigenous populations (most of whom are very poor) who, to make a living, use the forests in ways that harm the butterflies’ habitat (agriculture or logging).  As such, conservationists have begun working with these groups to incentivize them to take care of the Monarchs’ habitat.

In the United States, habitat destruction was a byproduct of new agricultural practices.  With the advent of genetically modified crops, specifically those that were engineered to be resistant to glyphosphate, the concomitant increase in pesticide use killed off native milkweed (the plant Monarchs lay their eggs on and the caterpillars feed on).  Without these plants, the Monarch butterfly populations dropped.

In a twist, recent efforts to plant milkweed to save monarchs appears to have backfired*.  As the article illustrates, people attempted to help by planting milkweed in their gardens at home.  Unfortunately, they planted the wrong species.  They planted a tropical species of milkweed, which in theory should not have mattered, but it did.  This species of milkweed did not die off in the winter months in the south like the native species would.  This caused two problems.  First, because it did not die off, Monarchs had no reason to continue their migration to the south and they ended up spending the winter in areas that they did not normally stay (though I could not find any information on whether this is a problem in and of itself).  However, it does directly lead to the second problem, parasites.  Milkweed hosts a parasite (Ophryocystis elektroscirrha) that is very debilitating to Monarchs, sapping them of energy to the point that they are unlikely to be able to make the full migration, dying along the way.

Normally, migration would “weed out” the infected butterflies so they do not pass the parasite on to their progeny.  Additionally, infected milkweed would die off during the winter months so when Monarchs return, they have a chance to use uninfected milkweed.  But because the tropical milkweed species doesn’t die off in the winter, Monarchs are staying put and getting infected with the parasite which is devastating to the already low Monarch population.

So what can be done to help?  The article points out that those who planted the tropical milkweed could remove it and plant a native species instead.  Or, if the native species is difficult to obtain, at least cut back the tropical plant every couple of weeks during the winter to encourage Monarchs to continue their migration south.  Also, the U.S. Fish & Wildlife Service is currently reviewing whether to list the Monarch butterfly under the Endangered Species Act.

So Steve P., there is definitely hope that a sustainable population can be maintained, which is good news for all the Lepidopterists out there (or anyone that likes to see the Monarchs migrate).

naturepl.com / Ingo Arndt / WWF-Canon

*The actual article is here but it is behind a paywall.

Blinded by Science blog 8: Why does the sun move?

Well folks, it was an incredibly stressful month of June and I was unable to complete a blog entry during that time.  For my readers (all 3 or 4 of you), I can only offer my apologies and tell you that it will never happen again.

REUTERS/Aaron Josefczyk

That’s how apologies work, right?

Anyway, in an effort to distract you all from the gaping hole that my lack of updating has caused in your lives, here is another question from my cute godson, G.  He asks, “Why does the sun move?”

Jeez, I cannot seem to get him off of this astronomy kick.  Is it too much to ask for some biology questions, things like, “Why are plants’ leaves green” or “Where do babies come from”?  Uhh . . . okay, you know what?  Let’s stick with astronomy for the time being, otherwise his mom might have a few “choice” words for me.

Well G, to answer your question, the sun does not actually move*.  It is actually the Earth that moves while the sun stays still.  When you asked why the sun doesn’t always shine, I told you that the Earth is really big and spins in space.  This means that the sun will shine on different places on Earth throughout the day.  If you remember, I had you perform a little activity to demonstrate.  Your mom stood behind you in a dark room and shined a flashlight at you.  As you stood in one spot and slowly turned to the left, the flashlight came into view (1).  As you continued to turn, you could soon see the entire flashlight (2).  And finally you would start to see less and less of the flashlight (3).

So because the Earth spins around in space, it seems that the sun is moving through the sky, but really the sun stays still.

*For those of you that aren’t three years old, my statement is not entirely true.

Hopefully this isn’t too obscure of a reference.

The sun does actually move.  It (and the entire solar system) revolves around the center of the Milky Way galaxy.  If an Earth year is the time the Earth takes to make one trip around the sun (365ish days), then a galactic year or cosmic year or whatever you want to call it takes roughly 230 million years.  Think of how few birthdays you would celebrate.

Blinded by Science blog 7: Do you really save any electricity and money by unplugging household devices when they are not in use?

Good day fellow humans.  It is I, your host, back for another tony edition of Blinded by Science.  And yes, you read that right, back for another TONY edition.  My name is actually an adjective meaning high-toned or stylish!  And as we all know, our names are permanent reminders used to fully describe who and what we are.

Who shall I be today?

Or not . . .

Anyway, today I will be answering a question from Steve P.  He asks, “Do you really save any electricity and money by unplugging household devices when they are not in use?”  Well Steve, this question reminds me of another question I have answered.  It turns out I was used as part of an ongoing marital argument when I answered that previous question so I hope that this is not the case now.  And if it is, I expect pay commiserate with the risk I am taking by getting involved.  I accept personal checks, cash, gift cards to delicious restaurants, and chocolate.

So now, let us get into today’s question.  Steve, the answer to your question is yes, unplugging electronics when they are not in use will save electricity and therefore money.  Though there is a caveat (when in life isn’t there?).  This only holds true for certain types of household devices – those that use standby power.  But what is standby power?  It is “electricity used by appliances and equipment while they are switched off or not performing their primary function.”  In other words, it is electricity that devices use when they are not in use.  Simple example, the little LED light on the front of the television that glows red when the TV is turned off (it changes color when you use the remote to turn the TV on).  It takes electricity for the light to be on, even though you have turned the TV off.  As another example, look at your microwave.  Even when the microwave is not in use, it uses electricity to keep the clock running.

The amount of electricity these appliances use is usually rather low.  According to studies done by Lawrence Berkeley National Laboratory, the majority of devices with standby power tested use less than 10 watts of electricity.  But having multiple devices in your home that use standby power can add up.

Let’s assume that the average device with standby power consumes 5 watts of electricity.  To convert that number into kilowatt hours (unit of energy consumption utilized by electric companies to determine cost) we must first multiply it by the number of hours that the device is on.  In one year there are roughly 8760 hours (24 x 365) that this device is drawing power.  So 5 x 8760 equals 43800 watt hours or 43.8 kilowatt hours.  The average price of residential electricity in the United States in March of 2015 is 12.35 cents per kilowatt hour.  So the average device with standby power costs a homeowner roughly $5.41 per year (43.8 kilowatt hours per year x 12.35 cents per kilowatt hour equals 540.93 cents per year).  That’s not too bad.  Unplugging this device permanently would basically allow you to have one more fast food dinner a year.  If the average house has forty of these devices, the cost then becomes roughly $216.37.  So unplugging these devices would save you quite a bit of money over the year which could be spent on other necessities.

Or a number of extra fast food meals

With that said, this only applies to devices that use standby power.  Electricity does not flow when an electrical circuit is not completed (think about how cars don’t move during a traffic jam because both lanes of a highway are blocked) so other devices, like lamps, that aren’t drawing electricity when turned off don’t need to be unplugged.  Also, you shouldn’t unplug all devices that use standby power either.  Refrigerators use standby power so they can continuously monitor the internal temperature and switch on when it gets to a certain point.  Unplugging a refrigerator would be a bad idea.

Nothing wrong here.  Just wipe it a bit and everything will be as good as new.  And delicious.

Well, I hope I’ve been able to help.  Tune in next time when I answer another of your burning science questions!