30079_56.pdf

CHAPTER 56

NUCLEAR POWER

William Kerr

Department of Nuclear Engineering

University of Michigan

Ann Arbor, Michigan

56.1 HISTORICAL PERSPECTIVE

1699

56.5 POLICY

1707

56.1.1 The Birth of Nuclear

Energy 1699

56.1.2 Military Propulsion Units 1700

56.1.3 Early Enthusiasm for

Nuclear Power

56.5.1 Safety

1707

56.5.2 Disposal of Radioactive

Wastes

1708

56.5.3 Economics

1709

1700

56.5.4 Environmental

Considerations

56.1.4 U.S. Development of

Nuclear Power

1709

1700

56.5.5 Proliferation

1709

56.2 CURRENT POWER

REACTORS, AND FUTURE

PROJECTIONS

56.6 BASICENERGY

PRODUCTION PROCESSES

1710

1701

56.6.1 Fission

1711

56.6.2 Fusion

1712

56.2. 1 Light- Water-Moderated

Enriched-Uranium-Fueled

Reactor

56.7 CHARACTERISTICS OF THE

RADIATION PRODUCED BY

NUCLEAR SYSTEMS

1701

56.2.2 Gas-Cooled Reactor

1701

1712

56.2.3 Heavy-Water-Moderated

Natural-Uranium-Fueled

Reactor

56.7.1 Types of Radiation

1714

1701

56.8 BIOLOGICAL EFFECTS OF

RADIATION

56.2.4 Liquid-Metal-Cooled Fast

Breeder Reactor

1714

1701

56.2.5 Fusion

1701

56.9 THE CHAIN REACTION

1715

56.9.1 Reactor Behavior

1715

56.3 CATALOG AND

PERFORMANCE OF

OPERATING REACTORS,

WORLDWIDE

56.9.2 Time Behavior of

Reactor Power Level

1717

56.9.3 Effect of Delayed

Neutrons on Reactor

Behavior

1701

1717

56.4 U.S. COMMERCIAL

REACTORS

1701

56.10 POWERPRODUCTIONBY

REACTORS

56.4. 1 Pressurized- Water

Reactors

1718

1701

56. 10. 1 The Pressurized- Water

Reactor

56.4.2 Boiling- Water Reactors

1704

1718

56.4.3 High-Temperature

Gas-Cooled Reactors

56.10.2 The Boiling- Water

Reactor

1705

1720

56.4.4 Constraints

1705

56.4.5 Availability

1706

56.11

REACTOR SAFETY

ANALYSIS

1720

56.1 HISTORICAL PERSPECTIVE

56.1.1 The Birth of Nuclear Energy

The first large-scale application of nuclear energy was in a weapon. The second use was in submarine

propulsion systems. Subsequent development of fission reactors for electric power production has

Mechanical Engineers' Handbook, 2nd ed., Edited by Myer Kutz.

been profoundly influenced by these early military associations, both technically and politically. It

appears likely that the military connection, tenuous though it may be, will continue to have a strong

political influence on applications of nuclear energy.

Fusion, looked on by many as a supplement to, or possibly as an alternative to fission for pro-

ducing electric power, was also applied first as a weapon. Most of the fusion systems now being

investigated for civilian applications are far removed from weapons technology. A very few are related

closely enough that further civilian development could be inhibited by this association.

56.1.2 Military Propulsion Units

The possibilities inherent in an extremely compact source of fuel, the consumption of which requires

no oxygen, and produces a small volume of waste products, was recognized almost immediately after

World War II by those responsible for the improvement of submarine propulsion units. Significant

resources were soon committed to the development of a compact, easily controlled, quiet, and highly

reliable propulsion reactor. As a result, a unit was produced which revolutionized submarine

capabilities.

The decisions that led to a compact, light-water-cooled and -moderated submarine reactor unit,

using enriched uranium for fuel, were undoubtedly valid for this application. They have been adopted

by other countries as well. However, the technological background and experience gained by U.S.

manufacturers in submarine reactor development was a principal factor in the eventual decision to

build commercial reactors that were cooled with light water and that used enriched uranium in oxide

form as fuel. Whether this was the best approach for commercial reactors is still uncertain.

56.1.3 Early Enthusiasm for Nuclear Power

Until the passage, in 1954, of an amendment to the Atomic Energy Act of 1946, almost all of the

technology that was to be used in developing commercial nuclear power was classified. The 1954

Amendment made it possible for U.S. industry to gain access to much of the available technology,

and to own and operate nuclear power plants. Under the amendment the Atomic Energy Commission

(AEC), originally set up for the purpose of placing nuclear weapons under civilian control, was given

responsibility for licensing and for regulating the operation of these plants.

In December of 1953 President Eisenhower, in a speech before the General Assembly of the

United Nations, extolled the virtues of peaceful uses of nuclear energy and promised the assistance

of the United States in making this potential new source of energy available to the rest of the world.

Enthusiasm over what was then viewed as a potentially inexpensive and almost inexhaustible new

source of energy was a strong force which led, along with the hope that a system of international

inspection and control could inhibit proliferation of nuclear weapons, to formation of the International

Atomic Energy Agency (IAEA) as an arm of the United Nations. The IAEA, with headquarters in

Vienna, continues to play a dual role of assisting in the development of peaceful uses of nuclear

energy, and in the development of a system of inspections and controls aimed at making it possible

to detect any diversion of special nuclear materials, being used in or produced by civilian power

reactors, to military purposes.

56.1.4 U.S. Development of Nuclear Power

Beginning in the early 1950s the AEC, in its national laboratories, and with the participation of a

number of industrial organizations, carried on an extensive program of reactor development. A variety

of reactor systems and types were investigated analytically and several prototypes were built and

operated.

In addition to the light water reactor (LWR), gas-cooled graphite-moderated reactors, liquid-fueled

reactors with fuel incorporated in a molten salt, liquid-fueled reactors with fuel in the form of a

uranium nitrate solution, liquid-sodium-cooled graphite-moderated reactors, solid-fueled reactors with

organic coolant, and liquid-metal solid-fueled fast spectrum reactors have been developed and op-

erated, at least in pilot plant form in the United States. All of these have had enthusiastic advocates.

Most, for various reasons, have not gone beyond the pilot plant stage. Two of these, the high-

temperature gas-cooled reactor (HTGR) and the liquid-metal-cooled fast breeder reactor (LMFBR),

have been built and operated as prototype power plants.

Some of these have features associated either with normal operation, or with possible accident

situations, which seem to make them attractive alternatives to the LWR. The HTGR, for example,

operates at much higher outlet coolant temperature than the LWR and thus makes possible a signif-

icantly more efficient thermodynamic cycle as well as permitting use of a physically smaller steam

turbine. The reactor core, primarily graphite, operates at a much lower power density than that of

LWRs. This lower power density and the high-temperature capability of graphite make the HTGR's

core much more tolerant of a loss-of-coolant accident than the LWR core.

The long, difficult, and expensive process needed to take a conceptual reactor system to reliable

commercial operation has unquestionably inhibited the development of a number of alternative

systems.

56.2 CURRENT POWER REACTORS, AND FUTURE PROJECTIONS

Although a large number of reactor types have been studied for possible use in power production,

the number now receiving serious consideration is rather small.

56.2.1 Light-Water-Moderated Enriched-Uranium-Fueled Reactor

The only commercially viable power reactor systems operating in the United States today use LWRs.

This is likely to be the case for the next decade or so. France has embarked on a construction program

that will eventually lead to productions of about 90% of its electric power by LWR units. Great

Britain has under consideration the construction of a number of LWRs. The Federal Republic of

Germany has a number of LWRs, in operation with additional units under construction. Russia and

a number of other Eastern European countries are operating LWRs, and are constructing additional

plants. Russia is also building a number of smaller, specially designed LWRs near several population

centers. It is planned to use these units to generate steam for district heating. The first one of these

reactors is scheduled to go into operation soon near Gorki.

56.2.2 Gas-Cooled Reactor

Several designs exist for gas-cooled reactors. In the United States the one that has been most seriously

considered uses helium for cooling. Fuel elements are large graphite blocks containing a number of

vertical channels. Some of the channels are filled with enriched uranium fuel. Some, left open, provide

a passage for the cooling gas. One small power reactor of this type is in operation in the United

States. Carbon dioxide is used for cooling in some European designs. Both metal fuels and graphite-

coated fuels are used. A few gas-cooled reactors are being used for electric power production both

in England and in France.

56.2.3 Heavy-Water-Moderated Natural-Uranium-Fueled Reactor

The goal of developing a reactor system that does not require enriched uranium led Canada to a

natural-uranium-fueled, heavy-water-moderated, light-water-cooled reactor design dubbed Candu. A

number of these are operating successfully in Canada. Argentina and India each uses a reactor power

plant of this type, purchased from Canada, for electric power production.

56.2.4 Liquid-Metal-Cooled Fast Breeder Reactor

France, England, Russia, and the United States all have prototype liquid-metal-cooled fast breeder

reactors (LMFBRs) in operation. Experience and analysis provide evidence that the plutonium-fueled

LMFBR is the most likely, of the various breeding cycles investigated, to provide a commercially

viable breeder. The breeder is attractive because it permits as much as 80% of the available energy

in natural uranium to be converted to useful energy. The LWR system, by contrast, converts at most

3%-4%.

Because plutonium is an important constituent of nuclear weapons, there has been concern that

development of breeder reactors will produce nuclear weapons proliferation. This is a legitimate

concern, and must be dealt with in the design of the fuel cycle facilities that make up the breeder

fuel cycle.

56.2.5 Fusion

It may be possible to use the fusion reaction, already successfully harnessed to produce a powerful

explosive, for power production. Considerable effort in the United States and in a number of other

countries is being devoted to development of a system that would use a controlled fusion reaction

to produce useful energy. At the present stage of development the fusion of tritium and deuterium

nuclei appears to be the most promising reaction of those that have been investigated. Problems in

the design, construction, and operation of a reactor system that will produce useful amounts of

economical power appear formidable. However, potential fuel resources are enormous, and are readily

available to any country that can develop the technology.

56.3 CATALOG AND PERFORMANCE OF OPERATING REACTORS, WORLDWIDE

Worldwide, the operation of nuclear power plants in 1982 produced more than 10% of all the elec-

trical energy used. Table 56.1 contains a listing of reactors in operation in the United States and in

the rest of the world.

56.4 U.S. COMMERCIAL REACTORS

As indicated earlier, the approach to fuel type and core design used in LWRs in the United States

comes from the reactors developed for marine propulsion by the military.

56.4.1 Pressurized-Water Reactors

Of the two types developed in the United States, the pressurized water reactor (PWR) and the boiling

water reactor (BWR), the PWR is a more direct adaptation of marine propulsion reactors. PWRs are

Table 56.1 Operating Power Reactors (1995)

Reactor Type a

PHWR

PWR

PHWR

PWR

BWR

PWR

BWR

PWR

BWR

PHWR

PWR

BWR

PWR

PHWR

LGR

BWR

PWR

BWR

PHWR

LGR

PWR

LMFBR

PWR

BWR

PWR

BWR

PWR

BWR

PWR

BWR

PWR

GCR

AGR

PWR

LGR

PWR

BWR

PWR

Country

Argentina

Armenia

Belgium

Brazil

Bulgaria

Canada

China

Czech Republic

Finland

Net MWe

1627

800

5527

626

3420

15439

2100

1632

890

1420

57140

15822

6989

1729

300

1395

17298

22050

7541

629

2760

1308

452

125

10175

9064

560

620

1632

1840

1389

5712

7370

2705

1385

1665

3104

1780

3360

8180

1188

1850

10245

32215

67458

0 PWR = pressurized water reactor; BWR = boiling water reactor; AGR = ad-

vanced gas-cooled reactor; GCR = gas-cooled reactor; HTGR = high-temperature

gas-cooled reactor; LMFBR = liquid-metal fast-breeder reactor; LGR =

light-water-cooled graphite-moderated reactor; HWLWR = heavy-water-moderated

light-water-cooled reactor; PHWR = pressurized heavy-water-moderated-and-

cooled reactor; GCHWR = gas-cooled heavy-water-moderated reactor.

Number in Operation

France

Germany

Hungary

India

Japan

Korea

Lithuania

Mexico

Netherlands

Pakistan

Russia

Slovenia

Slovokia

South Africa

Spain

Sweden

Switzerland

Taiwan

Ukraine

United States

operated at pressures in the pressure vessel (typically about 2250 psi) and temperatures (primary inlet

coolant temperature is about 564 0 F with an outlet temperature about 64 0 F higher) such that bulk

boiling does not occur in the core during normal operation. Water in the primary system flows through

the core as a liquid, and proceeds through one side of a heat exchanger. Steam is generated on the

other side at a temperature slightly less than that of the water that emerges from the reactor vessel

outlet. Figure 56.1 shows a typical PWR vessel and core arrangement. Figure 56.2 shows a steam

generator.

The reactor pressure vessel is an especially crucial component. Current U.S. design and opera-

tional philosophy assumes that systems provided to ensure maintenance of the reactor core integrity

CONTROL ROD

DRIVE MECHANISM

INSTRUMENTATION

PORTS

UPPER SUPPORT

PLATE

THERMAL SLEEVE

INTERNALS

SUPPORT

LEDGE

LIFTING LUG

CLOSURE HEAD

ASSEMBLY

CORE BARREL

SUPPORT COLUMN

HOLD-DOWN SPRING

CONTROL ROD

GUIDE TUBE

UPPER CORE

PLATE

CONTROL ROD

DRIVE SHAFT

OUTLET NOZZLE

BAFFLE RADIAL

SUPPORT

INLET NOZZLE

CONTROL ROD

CLUSTER (WITHDRAWN)

BAFFLE

CORE SUPPORT

COLUMNS

INSTRUMENTATION

THIMBLE GUIDES

ACCESS PORT

REACTOR VESSEL

RADIAL SUPPORT

LOWER CORE PLATE

BOTTOM SUPPORT

CASTING

Fig. 56.1 Typical vessel and core configuration for PWR. (Courtesy Westinghouse.)

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