Воробева Нуцлеар Реацтор Тыпес (Леарн то реад бы реадинг) 2010

МИНИСТЕРСТВО ОБРАЗОВАНИЯ И НАУКИ РОССИЙСКОЙ ФЕДЕРАЦИИ

НАЦИОНАЛЬНЫЙ ИССЛЕДОВАТЕЛЬСКИЙ ЯДЕРНЫЙ УНИВЕРСИТЕТ «МИФИ»

И.А.ВОРОБЬЕВА, С.Н.СМИРНОВА

NUCLEAR REACTOR TYPES

(Learn to read by reading)

Рекомендовано УМО «Ядерные физика и технологии» в качестве учебного пособия

для студентов высших учебных заведений

Москва 2010

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Learn to Read Nuclear English by Reading

Learn to take notes when dealing with texts

•Learn how to deal with notes

Notes record or hold fast information and ideas. They are a key step in changing a mass of information into knowledge that is useful for you.

You can take notes while listening, reading, or thinking. For example, think of what you do about the new words and phrases you hear or read when learning a new language. Where do they go? It is important to find a way of organising them according to a system you can understand when you look at those words and phrases again. Your system should also be open-ended: it should be possible to add further information to the original notes.

Pause for thought

How do you view the taking and keeping of notes:

•not important because I will remember anyway?

•not effective because 1 don't understand them

•important because they are vital for organising information in a` way that is meaningful for me,

•useful for helping to process and store information or ideas so that these don't just go "in one ear and out of the other"?

•useful for revising for an exam?

Note-Taking

Look at the list below and tick the strategies you use when taking notes when you read а text:

I make а list of the main points. I write down key phrases.

I highlight / underline the main ideas.

I highlight / underline important words/sentences. I underline descriptions, definitions, examples, etc. I use abbreviations and symbols.

I list and number items.

I write comments in the margin.

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I make tabIes, charts, grids, diagrams. I make spidergrams, mind maps.

I write out definitions, descriptions, examples, etc.

I group information according to comparison or contrast.

I classify the information according to а cause - effect principle. I write down the sequence of events.

I write а short summary.

UNIT I

INTRODUCTION TO NUCLEAR ENERGY

READING 1-A

Introduction to nuclear energy or which of the ideas below are new to you.

#1. What is the main use of nuclear energy?

The main use of nuclear energy is to generate electricity. This is simply a clean and efficient way of boiling water to make steam which drives turbine generators. Except for the reactor itself, a nuclear power station works like most coal or gas-fired power stations. Nuclear energy is best applied to medium and large-scale electricity generation on a continuous basis (i.e. meeting “base-load” demand). The fuel for it is basically uranium.

•Tell #1 making use of the following vocabulary:

Nuclear energy; generate electricity; drive turbine generators; coal or gas-fired power stations; medium and large-scale electricity generation on a continuous basis.

#2. Why use nuclear energy to make the steam?

Because it is clean, safe, and usually cost-competitive.

• Tell #2 making use of the following vocabulary:

Clean, safe, cost-competitive.

#3. Does nuclear energy have distinct environmental advantages over fossil fuels?

All the wastes are contained and managed – nuclear power stations do

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not cause any pollution. The fuel for nuclear power is virtually unlimited, considering both geological and technological aspects. That is to say, there is plenty of uranium in the earth’s crust and furthermore, wellproven (but not yet fully economic) technology means that we can extract about 60 times as much energy from it as we do today. The safety record of nuclear energy is better than for any major industrial technology.

Tell #3 making use of the following vocabulary:

• Wastes; cause pollution; virtually unlimited; the earth’s crust; wellproven technology; safety record.

#4. How much is nuclear energy used worldwide?

Nuclear energy supplies over 16% of the world’s electricity, more than the world used from all sources in 1960. Today 31 countries use nuclear energy to generate up to three quarters of their electricity, and a substantial number of these depend on it for one quarter to one half of their supply. Some 10,500 reactor years of operational experience have been accumulated since the 1950s by the world’s 440 nuclear power reactors (and nuclear reactors powering naval vessels have clocked up a similar amount).

Tell #4 making use of the following vocabulary:

For one quarter to one half of their supply; Some 10,500 reactor years of operational experience; the world’s 440 nuclear power reactors; reactors powering naval vessels; clock up.

READING 1-B

Common misperceptions about nuclear waste

Below are five commonly heard expressions of public concern that have arisen from an inadequate public debate about nuclear power – a debate in which facts have often been eclipsed by ideology and myth. The nuclear industry must bear some responsibility for these misperceptions and is striving to correct them:

Myth #1: The nuclear industry does not know what to do about nuclear waste.

Reality: The nuclear industry carefully accounts for all of its nuclear waste, and solutions for safely managing waste are comprehensively practiced and continually improved.

Myth #2: Nuclear waste lasts forever and cannot be managed safely.

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Reality: Nuclear waste naturally becomes less radioactive over time, ultimately becoming essentially non-radioactive. Most of the radioactivity in nuclear waste disappears within a few decades of its creation. Some of the radioactivity is less active and thus decays more slowly, requiring that some materials be isolated for tens of thousands of years. The nuclear industry has an excellent worldwide track record in safely managing nuclear waste. Accidents with health or environmental consequences have been extremely rare and invariably quite limited in effect.

Myth #3: Nuclear waste will end up in a “nuclear waste dump”.

Reality: Well-engineered and highly safe nuclear waste facilities do exist, and others are being developed or planned for long-term disposal of materials that pose the greatest radioactive hazard (i.e., HLW and ILW).

Myth #4: The huge cost for managing waste makes nuclear energy uneconomic.

Reality: The full cost for safely managing nuclear waste represents a few percent of the total cost of nuclear power generation and is generally included in the cost of electricity.

Myth #5: The nuclear industry is secretive about nuclear waste.

Reality: The nuclear industry routinely provides all relevant data to nuclear safety authorities about its waste. Upon review and verification, this information becomes part of publicly accessible national reports on the inventory of radioactive waste.

• Having made up a targeted vocabulary list get prepared for a talk on the myths and reality in class.

READING 1-C

Wastes

Industries utilize radioactive sources for a wide range of applications. When the radioactive sources used by industry no longer emit enough penetrating radiation for them to be of use, they are treated as radioactive waste. Sources used in industry are generally short-lived and any waste generated can be disposed of in near-surface facilities.

Nuclear power produces wastes which are contained and managed, with the cost of this being met by the electricity customer at the time. It does not produce any significant wastes which are dispersed to the environment. It

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therefore avoids contributing to increased carbon dioxide levels in the atmosphere.

The main wastes produced by "burning" uranium in a nuclear reactor are very hot and radioactive, placing them among the most unpleasant wastes from modern industry. However, these "high-level" nuclear wastes are modest in quantity. Handling and storing them safely is quite straightforward, they simply need to be shielded from human exposure, and cooled. Shielding can be by water, concrete, steel or other dense material, cooling is by air or water. For instance, when spent fuel is removed from a typical reactor, it is done under water and the spent fuel is transferred to a large storage pool where it may remain for up to 50 years.

About 30 kg of spent fuel arises each year in generating enough electricity for about 1000 people in the western world. The management and disposal of these wastes is funded from the time they are generated.

Other radioactive wastes also arise from the nuclear fuel cycle; these have greater volume but are more easily handled and disposed of. One characteristic of all radioactive wastes which distinguishes them from the very much larger amount of other industrial wastes is that their radioactivity progressively decays and diminishes. For instance, after 40 years, the spent fuel removed from a reactor has only one thousandth of its initial radioactivity remaining, making it very much easier to handle and dispose of.

•While discussing Wastes make use of the following vocabulary: Produce wastes; contained and managed; cost met by the electricity

customer; dispersed to the environment; contribute to increased carbon dioxide levels; high-level nuclear wastes; modest in quantity; handling and storing safely; shielded from human exposure; transfer to a large storage pool; management and disposal of; arise from the nuclear fuel cycle; progressively decays and diminishes; one thousandth of its initial radioactivity remaining.

•Develop the following notes:

Nuclear wastes management could result in the following:

•A risk of radiation exposure to workers or the public.

•Unacceptable radioactive contamination of the environment.

•The need to comply with regulatory waste disposal require-

ments.

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READING 1- D

The main industries that result in contamination

Oil and gas operations

Oil and gas exploration and production generate large volumes of water containing dissolved minerals. These minerals may be deposited as scale in piping and oil field equipment or left as residues in evaporation lagoons. Occasionally the radiation dose from equipment contaminated with mineral deposits may present a hazard. More significantly contaminated equipment and the scale removed from it may be classified as radioactive waste. Oil and gas operations are the main sources of radioactive releases to waters north of Europe for instance.

Coal burning

Most coal contains uranium and thorium, as well as other radio nuclides. The total radiation levels are generally about the same as in other rocks of the earth's crust. Most emerge from a power station in the light ash. Around 280 million tonnes of coal ash is produced globally each year.

Phosphate Fertilizers

The processing of phosphate rock to produce phosphate fertilizers (one end product of the phosphate industry) results in enhanced levels of uranium, thorium and potassium.

Process and Waste Water Treatment

Radionuclides are leached into water when it comes into contact with uranium and thorium bearing rocks and sediments. Water treatment often uses filters to remove impurities. Hence, radioactive wastes from filter sludges, ion-exchange resins, granulated activated carbon and water from filter backwash are part of RW contamination.

Scrap metal industry

Scrap metal from various process industries can also contain scales with enhanced levels of natural radionuclides. The exact nature and concentration of these radionuclides is dependent on the process from which the scrap originated.

Metal smelting sludges

Metal smelting slugs, especially from tin smelting, may contain enhanced levels of uranium and thorium series radionuclides.

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Research

Following the operation of a particle accelerator, the facility will generally be decommissioned. As radioactive materials will be present in the facility, these must be treated as radioactive wastes and handled accordingly.

Radiation sources utilized within universities and research institutions also require appropriate management and disposal. Many sources are of low activity and/or short half-life. However some exceptions include high-level long-lived sources such as Radium-226 and Ameri- cium-241 used in biological and or agricultural research. These require long-term management and disposal as Intermediate-Level Wastes (ILW).

Radiation

Ionizing radiation, such as occurs from uranium ores and nuclear wastes, is part of our human environment, and always has been so. At high levels it is hazardous, but at low levels it is harmless. Considerable effort is devoted to ensuring that those working with nuclear power are not exposed to harmful levels of radiation from it, and standards for the general public are set about 20 times lower still, well below the levels normally experienced by any of us from natural sources.

•While discussing make use of the following vocabulary

Ionizing radiation; uranium ores and nuclear wastes; human environment; hazardous; harmless; those working with nuclear power; exposed to harmful levels of radiation; general public; normally experienced.

READING 1-E

Transport of nuclear materials

Safety is the prime requirement with nuclear transports, particularly those of highly-radioactive spent fuel, and the record is impressive. Shielding, and the security of that shielding in any accident, is the key with any nuclear materials, especially those which are significantly radioactive. There has never been any radiation release from an accident involving such materials. For instance, spent fuel is shipped in large and extremely robust steel casks weighing over 100 tonnes, and each holding only about 6 tonnes of fuel.

•While discussing Transport of nuclear materials make use of the following vocabulary:

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