Chapter 3 - 9

09 Environmental Science Listen to a lecture in an environmental science class. Fill in the diagram with the information that you hear.

W: OK. We’ve been discussing some of the consequences of the use of nuclear materials on our planet−some of the accidents that have been caused, the impact on wildlife, things like that.

To finish up our chapter on nuclear problems, we’re going to cover how nuclear waste is disposed of. This is a huge problem. With all the nuclear power plants, the nuclear applications used by militaries around the world, and even the industrial use of nuclear material, there is an excessive amount of nuclear waste to dispose of.

The problem is, the options are limited. I mean, you can’t just pile nuclear waste into your local landfill.

It takes thousands of years before the radioactive isotopes start to decay and they aren’t dangerous anymore. So what do you do with all that unstable waste?

Well, one of the most common ways of getting rid of, um, nuclear waste is to process it to make it more stable. This can be done using a process called vitrification.

Basically, all it is, is adding sugar and lithium and then spinning it really fast in a hot cylinder.

It can also be condensed into a smaller volume by using ion exchange, or mixing it with special chemicals.

Then it’s sealed in a steel drum. I’m not talking about the kind of drum musicians use! I mean as huge steel barrel that is welded shut and then wash thoroughly.

Of course, after that, you still have to put the drum somewhere, because there is still a chance that the radioactive material will corrode the steel and seep out. Also, another problem with the radioactive waste is actually storing it.

There are a lot of, uh… a lot of ideas on this. And, you know, there um, there isn’t any answer that makes everyone happy.

But one thing to do with nuclear waste is to simply store it in huge storage bunkers. Scientists can kind of watch it then, monitor it to make sure it doesn’t leak.

Plus, the really dangerous parts start to decay after a few decades. So if they do decide to do something else with them, it’s not as much of a risk of contaminating things that are exposed to it.

OK. So, that’s one way of disposing of nuclear waste. Another common way of disposing of it is to put it in a secluded area of the environment−you know, like underwater or buried underground.

Oh, yes… this neutralizes its immediate danger to humans, but the danger to the environment is still massive. I mean, who knows what it could do to the vegetation and the animals in the area?

Underwater, it could put marine creatures at risk. A lot of people are concerned that−long-term, anyway−this could cause even more damage than most of the other options.

They don’t want to put the environment at risk just to store nuclear material.

Transmutation is an option that is being explored as well. It, uh, it involves… it’s kind of like changing the chemical makeup of the radioactive material into a type of nuclear waste that is less radioactive.

It uses nuclear reactors to process the material and make it less dangerous. Transmutation also allows it to be used in some kinds of industrial processes, so that it is “recycled” in a way.

Now, the… there’s one more possibility I want to discuss with you. That’s disposing of radioactive waste in space. Some people don’t want nuclear material just floating in space.

But a lot of people like this idea because it wouldn’t have any direct effects on the environment−the ground would be safe, the animals would be safe, the food would be safe.

However, there are several, um, several disadvantages. For one, it would take a lot of trips to space to get rid of all our used nuclear material.

This makes it financially unfeasible. Another reason disposing of nuclear waste in space is unappealing is that there is the possibility of a severe nuclear accident if one of the rockets carrying the material crashed.

1) Listen again to part of the lecture. Then answer the question.

To finish up our chapter on nuclear problems, we’re going to cover how nuclear waste is disposed of. This is a huge problem.

Why does the professor say this: To finish up our chapter on nuclear problems

2) Listen again to part of the lecture. Then answer the question.

Well, one of the most common ways of getting rid of, um, nuclear waste is to process it to make it more stable. This can be done using a process called vitrification. Basically, all it is, is adding sugar and lithium and then spinning it really fast in a hot cylinder.

Why does the professor say this: Basically all it is

3) Listen again to part of the lecture. Then answer the question.

Now, the… there’s one more possibility I want to discuss with you. That’s disposing of radioactive waste in space. Some people don’t want nuclear material just floating in space. But a lot of people like this idea because it wouldn’t have any direct effects on the environment.

What is the purpose of the professor’s statement when she says this: Some people don’t want nuclear material just floating in space. But a lot of people like this idea because it wouldn’t have any direct effects on the environment.