Alabama's STEM explorers is made possible by the generous support of the Holle Family Foundation established to honor the legacy of Brigadier General Everett Holle and his parents, Evelyn and Fred Holle, champions of servant leadership, science, technology, engineering, math, all coming up right now on Alabama STEM Explorers.

Welcome to Alabama STEM Explorers.

I'm Aubrey, and I'm here today at a nuclear power plant on the Tennessee River with my new friend Vinnie.

Thank you so much for coming here.

AUBREY We're glad to have you.

This is an overview of the Sequoia Nuclear Plant here on the Tennessee River.

Just going over some basic items at the top.

You have our intake station.

We bring water in from the Tennessee River and cool some of our major plant equipment and then discharge to the Tennessee River.

All that is is just cooling some of the residual steam in the plant non-radioactive items and discharging that water back out to the Tennessee River.

Coming further in your two canister items that you can see there are the the actual sealed buildings that housed the reactors for unit one on the far side and unit two on the near side for us, the control building is just to the left of that, and that's where all the operators control the operations of the units.

Behind that is the turbine building.

The turbine building houses a large turbine train.

There's a steam turbine that transmits the rotational energy that the steam gives it into the electrical energy that the generator provides to the grid.

All that energy and that electrical energy goes through transformers and into the switchyard from the switchyard it goes through transmission lines to various areas of the Tennessee Valley, eventually making its way into your house.

You're you're a circuit breaker that's in your garage or in a closet is where that power is eventually used.

Coming a little bit further this way, we have the diesel generators up on the hill.

There's diesel generators provide emergency power.

In the event that we were to have some type of catastrophic damage to the transmission lines that allows us to supply all the power that we need inside the buildings that we that we have all the equipment.

And just to keep the unit safely shut down, the units generate enough power for roughly a million homes to use, not just homes use our power, though we have a lot of direct serve customers such as Volkswagen in Chattanooga that has a huge battery plan as well as, you know, larger vehicle manufacturers in the area.

Do you have any questions about the layout here or any anything?

What are these big cooling towers?

Do?

So the cooling towers are not necessarily connected to the operation of the units.

However, we do have permits for the Tennessee River and how much that we can heat that river up.

So if it gets to the point where we see the temperature rising on the Tennessee River, we can put the cooling towers in service and instead of just discharging the water back to the Tennessee River, we pump it to these cooling towers and just allow natural convective currents to pull the heat out of that water and turn it into moisture laden vapor.

So seeing those cooling towers in service does not directly show that anything is getting discharged from the plant.

All it's showing is that we're just cooling the river water down that we borrowed from the Tennessee River and we're bringing right back to the Tennessee River.

It's not radioactive.

All it is is just moisture laden vapor, basically a cloud generator, but they're very big.

Why is it so important to make sure that the river doesn't get too hot?

So the reason why the environmentalists are concerned with the river temperature is, you know, it's a huge ecosystem in the Tennessee River.

So you want to make sure that you're not heating up or cooling down large portions of the river very quickly just to prevent any type of biological life that's happening in that river from being affected, as well as any growth like the actual plants and marshes and grasses that grow in the river from being affected as well.

So just keeping that permit allows us as one plant to say, hey, we're regulating this portion of the river to make sure that we are in the best interest in the health and safety of of the people in the Tennessee Valley.

How come the cooling towers are so much larger than anything else in the plant?

Well, you look at the water volume that is required of them and that huge skirt has to get filled up with water in order to use it.

So the larger the cooling tower, the more effective it can be used.

And generally, whenever they built the plant, we actually had room for additional cooling towers, but they ended up only building these two.

And to be honest, you could operate the plant without the cooling towers.

It just helps with the environmental concerns.

Why is making energy from like a nuclear plant better than other methods?

Well, it all has to do with energy density.

For one thing.

You know, a coal plant that has the same output of us while taking up the same footprint on the land it would have to use in the millions of pounds of coal in order to generate and in addition to just getting that carbon monoxide and carbon dioxide emissions from that burning, you also have to store some of the ash that comes off of it.

So from a footprint, we use a lot more energy dense uranium in order to make the same amount of heat that a coal plant that would burn a whole lot of of coal and have a whole lot of storage issues with a lot of that for a lot of that fly ash.

So coal is something that I think most people are familiar with, but uranium is in.

So can you tell me exactly what that is?

Yeah.

So uranium is naturally occurring and we use uranium in the cores to fission and fission is basically taking a uranium atom and hitting it with a neutron and causing it to split or fission into two other items.

And with that splitting, you end up having a small amount of the mass that's converted to energy.

And when you do that on an atomic scale in hundreds of thousands or millions of these are happening at any given time, you end up with a lot of heat generation.

So with coal you light a match and you burn coal to get heat with uranium you are bombarded with neutrons, cause it to split and it generates a crazy amount of heat, you know, on the on the upwards of 5 to 7 pounds of uranium that we split a day at 100% operation versus 1.2 - 1.3 million of coal that would have to generate the same amount of electricity.

So you said one of the issues with using coal is that they have to store so much ash.

Is there anything that you have to store while using nuclear power?

Yes.

So with nuclear power, after about an 18 month cycle, we go through what's called a refueling outage and all of our fuel goes through three cycles.

So 318 month cycles, all of our fuel goes through.

At the end of that third 18 month cycle, we pull the fuel out and it goes into a spent fuel pool.

That fuel still generates a small amount of heat for many, many years, and we just keep it cool.

Now, after a period of time, the heat generation on that fuel bundle is so low that we can move it into what's called dry storage.

And dry storage is where you put it into a canister and just let it sit on a concrete pad and so we store all of our used fuel.

Since these units have been running since the early eighties, we store them all on a pad just behind all the reactors.

It's annotated here by just that large green area.

There's none here on this specific market, but we have a place at the plant where we store all of our used fuel.

There is some works in the government to get a permanent storage location for all the nuclear plants in the country.

But that's just kind of been tied up for for many, many years now.

Why would it be beneficial to have a place where all of the nuclear plants could store their use?

So what would be beneficial for that is, you know, if you ever do end up retiring the nuclear plant, there always becomes a question of what do we do with this fuel that's sitting on this football field sized concrete pad?

What do we do with it?

So at that point, either it has to get absorbed by another by another site.

Something has to happen to it, because if you end up turning this into a park or turning this into a housing development, you know, in the years and centuries to come from now, you have to figure out what to do with that used fuel.

So that's why it's important having a single repository for the entire nation would mitigate that risk and would also allow us a place to store that.

Well, since you don't have this nationwide storage space, how do you ensure that none of the waste does leak out into the environment?

So we have several barriers.

We have three specific barriers to prevent us to protect the health and safety of the public, the first being the fuel barrier.

So the way the fuel rods are constructed, we have uranium pellets inside of a cylinder that's steel welded and all the heat is transferred through that fuel bundle into the water.

So that's your first barrier.

The second barrier is the cooling system that that water is in.

It's a steel welded pressure vessel as well and is monitored for leakage via humidity detectors as well as radiation detectors to ensure that nothing is leaking out The third barrier.

The cylinder buildings are cylindrical buildings, the steel buildings.

If something makes it past that first barrier and then makes it past that second barrier that shield building will stop it.

And inside that shield building, you know, it's reinforced concrete on the outside.

And then there's a gap layer and then there's a steel containment vessel on the inside of that.

So it's almost a building inside of a building.

And in that intermediate layer there, systems that keep the intermediate layer at a negative pressure to where if anything leaks out and challenges that steel containment vessel, it'll get collected before it makes it through that reinforced concrete barrier.

So those are those three barriers that prevent us from discharging anything out to protect the health and safety of the public.

Now, all that being said, each of those barriers are monitored.

You know, you have radiation monitors, fluid monitors, process monitors that are ensuring that we have the integrity of those three barriers.

So those are monitored 24, seven, 365 days a year.

Well, since there's clearly a lot of things that you do to protect it from the public, how do you make sure, like, is it unsafe for the workers who work here to be around all the radioactive materials?

No, not at all.

So there's obviously controls in place to prevent someone from going to areas that they shouldn't be highly have locked, areas that you can't access that power, administrative controls and things of that nature as well as general public.

You know, we have an entire security force that's dedicated to the security of the plant just to prevent anyone from coming in that wants to cause damage, nuclear or non-nuclear.

So there's a tiered approach there as well.

You know, you only certain amount of people can get on site.

And then in critical areas, only certain people are allowed in critical areas.

And then within those critical areas, you have special training to determine what you need to do and what your specific job is.

Any time you go out for a job, you're going to have a brief just to ensure you know the details of your job, where you're going to be going, as well as if you see anything strange to stop, get out, get everybody else involved so that you understand what the what the details of the job are and anything that you came across.

So all about the control building and how it controls the reactors.

How about we go take a trip over here to the simulator?

We have a mock up of our entire control room and let you operate some stuff in the control room.

That sounds great.

So being a part of TVA and showing what TVA is capable of for this specific area, looking at the Tennessee Valley and the technological advances that we've had is very impressive.

So being able to be part of that, being able to generate the power for the STEM schools, for the hospitals, for the individuals, being able to generate that power at a low cost rate for the general consumer allows that technological advance to happen at a much quicker rate, not only just for our area but also for the nation as well as the world, for the nuclear renaissance and trying to help more information as well as technology into the nuclear nuclear fleet and just being able to to proliferate nuclear throughout the throughout the world as best we can.

So for the younger individuals that are watching the show, are you curious?

Do you want to know how things work?

I would strongly suggest you to continue to foster that and be able to ask those questions.

If you're not sure if something continue to ask, even if someone can't give you a direct answer, ask them.

Who else would know?

Continue to be curious if at any point you stop being curious, ask yourself why you're not curious anymore.

So continue to be curious and ask yourself questions.

All the time and challenge others.

Challenge your friends and challenge yourself.

This is where we train our operators on how to operate the plants for normal operations.

Well, we're just making electricity for the Tennessee Valley.

Or if when things might not go quite right and we can train the operators in order to mitigate those events and respond to protect the self safety of the public.

So I'm in this room.

So there's a lot of stuff in here.

This is not unlike a flight simulator.

This control room simulator is designed to completely mimic .

unit one plant down to the floor and every single label on every single switch you see in here.

So in here, we can operate any piece of equipment, I can break any piece of equipment for the operators to go mitigate that, or they can just practice operating a plant like they do every day.

Yeah.

How come there are so many switches?

So each one of these switches and controllers and indicators in the real plant would be attached to a real piece of equipment.

It could be a big part, a small part, it could be a valve, it could be a flow meter.

But in order to run this plant, it's a very complicated piece of equipment and everything needs to have the ability for the control room staff to monitor that, turn it on, turn it off as needed in order to operate this plant.

So I notice you have a little bit of color coding going on.

How is that helpful?

Okay.

So the color codes are set up by a plant system.

So if we look around, we'll see some red switches.

The red switches are typically electrical distribution, so that might go to a big circuit breaker or a transfer switch that might that moving on down or the orange switches or has to do with what we call heater drains and that so we have a feed water heating system for the water that gets pop back into the steam generators and that helps heat that moving on down, we have blue systems.

The blue systems are the non contaminated non-radioactive feed water that gets pop back in the steam.

Generators get boiled back off in the steam to spend the turbine moving a little further to the right.

The our system over there, that's also steam.

Then to my left on this side of the plant is all green.

Most of these systems are safety related or reactor court system related items.

They keep the core cooled.

So what are all the little squares up above all the switches?

Good question.

So as you'll see, if I look on the top of the panels, there are multiple numbers of squares and each one of those can light up or flash in order to alert the operator that something happened.

It could be something abnormal or it could be something that's expected.

But each one of those is associated with a procedure.

The operators would see that an alarm come in, they would pull a book out and then address that condition as needed.

Some of them are read border and the red border ones are a little bit more priority.

That's how we don't of those.

Why is it important for there to be multiple controls that do basically the same thing?

Okay.

So on a reactor side, we have in order to maintain this plant safe, the plant's design, that if anything happens, I can have practically half my equipment break or not work, but the systems will still keep the reactor cool.

So there's two at least two of everything that is required to do that.

So again, an entire we call train half of the systems could fail to operate, yet we would still be able to protect the public and our people at the plant.

What would you do in the case that you would have to completely shut everything down?

Okay, so in order to shut the reactor down, it's actually a lot easier than you think.

The challenge for an operator is actually keeping these units online for 18 months before the refueling cycle.

So if I did nothing, the reactor would actually slowly shut itself down all by itself.

The operators actually have to do these things every couple of hours in order to keep the reactor at a percent power.

So the shot, the reactor down, if I want to do it right now or is actually I turn one switch and we'll get through that later and it will turn the entire reactor off.

It will go from a hard power to about 0% power in less than 2 seconds.

And that would immediately take away all electricity generation and the reactor will be safely shut down.

Since the reactor constantly needs a person to be like working on it.

Is there always someone here like operating it in our actual plant?

We have a mirror image of where we're standing on the other side of the room for a unit to.

So for example, on unit one, I would have two, what we call reactor operators.

They're licensed by the Nuclear Regulatory Commission that they would be operating the equipment at the control boards down here.

I'm standing right over here.

We would actually have what's called a senior reactor operator that is licensed by the Nuclear Regulatory Commission as well.

And he's in charge or she's in charge of this entire unit's operation in the middle of the room.

Kind of that way you would have what's called a shift manager with that person's in charge of the entire site operation.

And that person is also licensed by the Nuclear Regulatory Commission.

And then on Unit two down there at the other side, we'd have the exact same number of people as well.

So there's always about seven people in the control room.

So do you want to operate this record a little bit and adjust some megawatts, maybe even shut it down?

Yeah, it's okay.

Let's go.

All right.

So do you want to lower our plant's power a little bit?

Yeah, that sounds cool.

All right, well, right now we're at 1211 megawatts.

That's enough power for about 600,000 houses.

So a lot of houses.

Yes.

So in order to lower power a little bit, this is our turbine controls right here.

So I'm going to have you push this center button until that center says about 83.

So let's push that button a couple of times.

It's also 83 or more.

Here you go.

All right.

So now the center is ready to go.

But again, we want to be safe.

So at this point in the plant, people will be validating this is what we want to do, double checking.

And when they're already do that, they would go, So go ahead, go.

So now in the plant, what's happening is the turbine control valves are now closing down and lowering the amount of steam that's going into the turbine so that turbines going to make it less electricity.

So this reference number right here is actually the turbine position as it's going close.

Not very fast as you can see.

If you remember, we started at 1211 megawatts.

And over there we can see that number is going down.

Now we're down to 1207 megawatts.

So we lost about six megawatts, which is about the size of three big wind turbines, just that much there.

So about how many houses did we just like essentially take power away from just now?

Okay, so we've lowered power about 20 megawatts total, and that 20 megawatts is about 10,000 houses worth of electricity just in that 3 minutes.

So we just lowered power.

All right.

Already.

So we just lowered our turbine power.

Now we're going to lower our reactor power.

So this is going to hurt control rods.

Slow down the chain reaction of the neutrons to actually lower our reactor power.

As we see it right now, our reactor power is a little over 99.6%.

So in order to lower that power, we're going to insert our control rods into the core.

So I'm going to have you do is take this rod control selector switch to right here.

It says manual and.

Yep.

Oh, one, one, two, three.

That's all right.

Okay, stop right there.

So now we have a rod control switch.

We can go out or in.

So go ahead and take this joystick and push them in and we're going to insert contro And as you can see, our record power saw off a 99.6%, and we're right down to 99.2%.

So that's how I would adjust a reactor power at our power plant.

All right.

All right.

So you're ready to shut this record down?

About 2 seconds.

I'm ready.

All right.

So we have a switch right here.

It's called reactor trip.

That red switch, if you just turn that to work, says trip, you're going to shut this thing down.

All right?

So now I'm.

All the control rods just went fully into the reactor core to stop the chain reaction.

So we're no longer producing any significant amount of fission.

As you can see, a lot of alarms are going off.

And this happened at a plant.

All the operators will be doing those, be going around and making sure everything happened as expected.

This is not an emergency condition.

This is not a great day because we're not making electricity, but nothing's broken.

There's nothing unsafe about this.

All the reactors now shut down was pretty easy.

Pretty easy.

They're pretty easy.

It's a lot more challenging to keep you online for 18 months in order.

So then you shut it down.

Shutting it down is very easy.

So whatever you're saying, come on over here.

Absolutely.

So we have multiple opportunities here at our TVA, nuclear power plant.

So we have operations.

That's the people that are going to be in the room you're in.

And we'll talk a little more how we get to that later.

We have engineers that work supporting our plant every day and designing and modifying our plant equipment.

We have technicians that are electricians, instrument maintenance, mechanics, mechanics themselves, all supporting the equipment that's in the plant.

But the kind of fun stuff is what we're at.

That's the operators kind of what you just had got a taste of.

And we know how to get into that stuff.

Yeah.

What kind of training would you have to go through?

So there's actually a whole lot of different potential past in order to get to operate in this control room.

You actually don't need a college degree to do it with or not.

One path is in our nuclear navy.

It's one way to in order to serve on nuclear submarines or nuclear craft carriers, get out of the military.

And then that would be one avenue.

But outside of that, we have hired people, worked in the post office.

They've come in and learned how to be operators in the plant.

And once they do that, they can actually be selected and get their NRC license after going through a training program that involves a whole lot of time in the classroom and in here, on average, it takes about two years for each program to get step up.

So the program for somebody off the street again, postal worker or pizza delivery person can walk in with the right science technology background from high school, go through an 18 month program, get qualified, and they can come in and get a NRC license effort or two year program, all paid for by the company.

So we talk a little bit about the initial training in order to get that license to come operate.

Well, it doesn't stop there.

This room that we're in right now is used every day of every week.

We have operators that come in and we test them constantly to make sure they can safely operate this plant every five weeks.

And our goal is to be as realistic as possible, down to the alarms, the sounds, and even some other things that we put in.

Like we've actually simulate earthquakes now so we can make this whole room shake, make a whole lot of noise, and the operators can actually respond to that.

And it's pretty realistic out here, something I do.

So that's our relatively new earthquake simulator.

But in order to make that happen, this has got a bunch of speakers under our feet right now.

It's going to shake the whole room and so have the operators that are in here can start to learn and actually kind of experience this and respond to it in a safe simulated environment that's not in the play.

Yeah, you can feel the floor shaking.

Yeah, that's pretty cool for you.

Proud of it.

This is, again, relatively new feature we just got and I like it.

It's definitely adds that realism in order to make sure that we're the safest we can possibly be.

Why is having the earthquakes similar or like specifically earthquakes, why did you choose to make that well?

Well, we already have all the lights and switches and buttons and stuff, but this is a obviously previously we have procedures for earthquakes and we were kind of trained on it and tell the person how you feel the ground shaking.

And it was like, okay, and then we go do what they're supposed to do.

Well, now we can add that realism.

And it was relatively easy to do, and it just really changes the feeling in here when that happens.

Why is it important to continually test the operators?

Because as you're looking around, there is a lot of stuff going on in this plant and there is no way people can always remember that.

So we train and test operators costly to maintain that knowledge and ability to protect the people that work at the plant and outside the plant.

Now I think that's definitely useful because I know during the summer I usually forget a lot of the things I learned so well.

Thank you so much for having me here today.

Oh, it was great.

I'm so glad you came out here.

We got to show you a little taste of what it's like to work in the control room of a nuclear power plant.

We'll see you next time on Alabama STEM Explorers.

Thanks for watching.

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Alabama STEM explores is made possible by the generous support of the Holle Family Foundation established to honor the legacy of Brigadier General Everett Holle and his parents, Evelyn and Fred Holle, champions of servant leadership.