S1E2 – Nuclear Power Plants Essentials – Core Concept Transcript
This is a transcript of the video S1E2 – Nuclear Power Plants Essentials – Core Concept
G’day and welcome back to the Engineering All Sorts Video Courses – professional development for teachers, helping you to Engineer your Expertise. My name is Daniel, and I’m your navigator of all things Engineering. I’m also the founder of Engineering All Sorts, where we’re all about Engineering for Educators – stem education to help you to be confident in the details – over at engineeringallsorts.com.au.
In this video we’ll be taking our first step into nuclear power plants covering the core concept. We’ll look at what each part does and how energy is transferred from Fission to electricity. We’ll also start to look at the system through the eyes of an engineer to determine what needs the most consideration.
At the end of this video you’ll be able to:
- Identify the different components of a nuclear power plant in form and function
- Describe the flow and conversion of energy through a nuclear power plant
- Define the differences and similarities between a nuclear power plant and other thermal power plants
- Cite and quantify key operating parameters of a nuclear power plant, such as operating temperature and pressure
- And contrast key considerations in the creation and operation of a nuclear power plant, such as safety, cost, physics, ease of construction and maintenance, and politics
For the full list of learning outcomes and transcripts for this series, check out the downloads section of the series at engineeringallsorts.com.au
But now it’s finally time to take our first step into the nuclear power plant, so let’s take it apart!
Here we have a number of empty buildings, some of which you may recognise if you’ve ever driven past a nuclear power plant. This will look very similar to a coal power plant as well, as they are both thermal power plants, so you may recognise the buildings even if you don’t have any nuclear power plants nearby.
A nuclear reactor produces and controls the release of energy from splitting atoms, to create expanding steam to drive turbines, so let’s draw these in as we go
Let’s start with the reactor, which is where the heat comes from through the fission process. Don’t worry, we’ll take a closer look at each of these components in later videos, but it’s important to take in the whole picture first.
Heat is transferred to water which travels out of the reactor to the steam generator. This popular method is called the Pressurised Water Reactor, and the water is usually about 300degC (which is about 570Farenheit), and at a pressure of 150 atmospheres, which basically means that it is 150 times the normal pressure of Earth’s atmosphere. This water is pressurised this much so it doesn’t boil.
So this very hot water in a pipe in the steam generator is used to heat up the second circuit of water, and when it’s given up all its heat it returns back to the reactor to get more heat.
The second circuit of water is definitely supposed to boil and create steam. This steam then leaves the reactor building and heads to the turbine and generator building.
The steam enters the turbine, where it expands and cools, causing the turbine blades to spin. The blades spin the main shaft which is connected to the generator which uses the rotation to generate electricity which is fed to the electricity grid.
But we still have to close the second water loop, as the cool steam has nowhere to go. We have to make sure it becomes water before we send it back to the steam generator, so we will send it through the condenser. This steam travels through a pipe surrounded by water from a third circuit, and cools enough to become water again, before being pumped back to the reactor building.
Finally, all that waste heat from the condenser has to go somewhere, and this is where the concrete tower comes in. This is called a cooling tower and it uses evaporation cooling to cool the third circuit of water so it can keep cooling the steam over and over. Unfortunately, this excess heat can’t be used to generate electricity in the turbine, as allowing the steam to condense in the turbine will damage the turbine blades. This is why this heat is called waste heat.
So what we have seen here is that the nuclear power plant is basically a way of turning heat into electricity. We will look at the full energy transfer soon, but first let’s consider a few important points that an engineer would have to think about.
In a Nuclear Power Plant, it’s all about maintaining the right balance of safety, cost, physics, ease of construction, ease of maintenance and politics.
First and foremost in the eyes of a nuclear power plant engineer is safety of the workers and safety of the surroundings. As we will see in future videos, there are many controls put in place to make sure that the complex fission reaction and radiation is controlled. When a fission reaction becomes uncontrolled and damages the core, it’s called a nuclear meltdown, such as the events at Three Mile Island, Chernobyl, or Fukushima Daiichi.
We spoke about coal power plants before. Really the only main difference between this and a coal power plant is that coal is burned to create heat, instead of nuclear fission. A whole lot more coal is needed to make that heat though. 1 single kilogram of uranium is equivalent to 4500 tonnes of coal. As a result a coal power plant needs to be pretty close to the coal mine to make sure you don’t have crazy coal transport costs. Unfortunately, the coal mine is never near the cities (what we call the load), so then you have to have long electricity cables to feed the city network. A nuclear power plant has much lower fuel transport costs, so you can keep the power plant closer to the city and reduce the electricity cabling costs.
We also have to consider ease of construction and ease of maintenance. As we will see in the examples in later videos, making something easy to maintain will often increase construction costs, and vice-versa, so it’s important to find the right balance.
Lastly, there are political issues at play when considering a nuclear power plant. You might have the design for the safest, most environmental nuclear power plant ready to be built, but if the residents nearby aren’t happy with nuclear power, you’ve got problems. Nuclear power plant failures are high-profile and the effects are long lasting. The Chernobyl meltdown occurred in 1986, and we are still dealing with controlling the radiation even today.
Let’s stop for a quick activity. Grab a pen and paper or open up a text editor on your computer or phone, or download and print the worksheet for this episode from the download section at engineeringallsorts.com.au. Have a think about what we’ve discussed so far, as well as your own prior knowledge and experiences with nuclear power plants.
What are the Pros and Cons for building a new nuclear power plant near where you live? As a bonus, also consider and write down anything that could be done to alleviate or mitigate the Cons.
Go ahead and write all these down. Just pause the video to give yourself enough time, and then come back to us when you are done. I’ll be right here!
Ok, so all done with your Pros and Cons? Maybe you’ve got some of things we’ve spoken about already, and maybe some new things. It would be great if you could share your answers in the comments section below. If you’d also like to share where your new nuclear power plant is going to be built, that would be awesome!
Ok so there’s one last thing to cover in this video, and that’s the energy conversion concept. Remember, what we are trying to do is get from Uranium to electricity.
Let’s start with Uranium over here on the left. The uranium creates heat which is transferred to water. This water then becomes steam (this is the second circuit of water that we saw before). The steam heads to the turbine where it converted to mechanical energy of the rotating shaft. This mechanical energy is this turned to electrical energy in the generator and fed to the electricity network.
The cooled steam needs to be condensed to back to water, so the heat is taken away by the cooling water, the third circuit of water. Lastly, the cooling water’s heat is dumped to the atmosphere using the cooling towers.
So this is how we get electricity from fission heat, and deal with the waste heat.
We’ve covered a lot of ground in this video. We looked at the different components of a nuclear power plant including the reactor, steam generator, turbine, electricity generator, condenser, and cooling towers. We looked at the conversion of energy through each component, from heat energy in the reactor, to heat energy in the water and steam, and then to mechanical energy in the turbine, and finally electrical energy in the generator. And we covered some key engineering considerations such as safety, fuel and energy transport, and public opinion.
Don’t forget you can check out the resources for this series and more professional development for teachers at engineeringallsorts.com.au, including learning outcomes, transcripts and worksheets.
If you haven’t left your comments below from the activity above, it would be great if you could also share that below, so we can all share our stem education.
But this video has only scratched the surface. Each of the videos to come will dive deeper into each of the components of the nuclear power plant, to find out how they all work. In the next video we will look closely at the reactor and the steam generator. I’ll see you there!
This is a transcript of the video S1E2 – Nuclear Power Plants Essentials – Core Concept