Environmental Encyclopedia

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Environmental Encyclopedia 3

Nuclear power

steam from being released into the

environment

. A second

type of nuclear reactor makes use of a heat exchanger. Water

around the reactor core is heated and pumped to a heat

exchange unit, where this water is used to boil water in an

external system. The steam produced in this exchange is

then used to operate the turbine and generator.

There is also a type of nuclear reactor known as a

breeder, or fast-spectrum reactor because it not only produces

energy but also generates more fuel in the form of plutonium-

239. In conventional reactors, water is used as a coolant as

well as a moderator, but in breeder reactors the coolant used

is sodium. Neutrons have to be moving quickly to produce

plutonium

, and sodium does not moderate their speed as

much as water does. Another design, the CANDU reactor,

(acronym for CANada Deuterium Uranium) uses deuterium

oxide (heavy water) as moderator and natural uranium as

fuel. With the uranium fuel surrounded by heavy water,

chain reaction fission takes place, releasing energy in the

form of heat. The heat is transferred to a second heavy water

system pumped at high pressure through the tubes to steam

generators, from which the heat is transferred to ordinary

water which boils to become the steam that drives the turbine

generator.

Nuclear power plants could never explode with the

power of an atomic bomb, because the quantity of uranium-

235 required is never present in the reactor core. However,

they do pose a number of well-known safety hazards. From

the very beginning of the development of nuclear reactors,

safety was an important consideration as scientists and engi-

neers tried to anticipate the dangers associated with nuclear

reactions and radioactive materials. Thus, control rods were

developed to prevent the fission reactions from generating

too much heat. The reactor and its cooling system are always

enclosed in a containment shell made of thick sheets of steel

to prevent the escape of radioactive materials. Nuclear power

plants are highly complex facilities, with back-up systems

for increased safety which are themselves supported by other

back-up systems. But the components of these systems age,

and human errors can and do occur; safety measures do not

always function the way there were designed.

On December 2, 1957, the first nuclear power plant

opened in Shippingport, Pennsylvania, and to many the

nuclear age seemed to have begun. Over the next two de-

cades, more than 50 plants were commissioned, with dozens

more ordered. But safety problems plagued the industry.

An experimental reactor in Idaho Falls, Idaho, had already

experienced a partial meltdown as a result of operator error in

1955. In October 1957, just months before the Shippingport

plant came on line, a production reactor near Liverpool,

England, caught fire, releasing radiation over Great Britain

and northern Europe.

997

The most critical event in the history of nuclear power

in the United States was the accident at the

Three Mile

Island nuclear reactor

near Harrisburg, Pennsylvania. In

March 1979, fission reactions in the reactor core went out

of control, generating huge amounts of heat, and a meltdown

resulted. Fuel rods and the control rods were melted; the

cooling water was turned to steam and the containment

structure itself was threatened. No new plants have been

ordered in the United States since this accident, and 65

plants on order at that time were cancelled. The explosion

at the Chernobyl reactor near Kiev, Ukraine, dealt a second

blow to the industry.

Even without these accidents, another problem with

nuclear power would remain. This is the problem of spent

radioactive wastes. About a third of the 10 million fuel pellets

used in any reactor core must be removed each year because

they have been so contaminated with fission by-products that

they no longer function efficiently. These highly radioactive

pellets must be disposed of in a safe fashion, but 50 years

after the first controlled reaction, no method has yet been

discovered to address this issue. Today, these wastes are

most commonly stored on a temporary basis at or near the

power plant itself. Many have argued that further develop-

ment of nuclear power should not even be considered until

better methods for

radioactive waste management

have

been developed.

The International Nuclear Safety Center (INSC),

which operates under the guidance of the Director of Inter-

national Nuclear Safety and Cooperation in the

U.S. Depart-

ment of Energy

(DOE), has the mission of improving nu-

clear power reactor safety worldwide. The INSC is dedicated

to developing improved nuclear safety technology and pro-

moting the open exchange of nuclear safety information

among nations, sponsoring scientific research activities as

collaborations between the U.S. and its international part-

ners. Safety issues are addressed at several levels, including:

risk assessment

, containment, structural integrity of reac-

tors, assessment of their seismic reliability, equipment opera-

bility, fire protection, and reactor safeguards.

The security of nuclear facilities has also been a point

of growing concern. In 1991, the NRC instituted an Opera-

tional Safeguards Response Evaluation (OSRE) program,

which evaluated the ability of nuclear facility security person-

nel to withstand a staged commando-style attack by intrud-

ers. Unfortunately, six of the 11 evaluations performed in

2000 and 2001 resulted in the “attackers” being able to

penetrate security and simulate damage to reactor

equipment.

In the post-September 11 terrorist attack environment,

the vulnerability of America’s 104 nuclear power facilities

are a critical national security concern. All nuclear facilities

were placed on high alert immediately following the attacks,

Environmental Encyclopedia 3

Nuclear power

Nuclear power plants are a peacetime application of energy initiated through nuclear fission. (Photograph by

Robert J. Huffman. Field Mark Publications. Reproduced by permission.)

and in early 2002 the

Nuclear Regulatory Commission

(NRC) issued interim confidential security orders for all

licensees to comply with. In addition, decommissioned nu-

clear plants and spent fuel storage facilities were also required

to implement the security orders. The NRC also conducted

a thorough review of its Internet web site, taking the site

offline temporarily to analyze content and remove all docu-

ments deemed sensitive to national security. In April 2002,

the NRC announced the establishment of a dedicated de-

partment for plant security, the Office of Nuclear Security

and Incident Response.

The future role of nuclear power in energy production

throughout the world is uncertain. But the current absence

of nuclear power plant development in the United States

should not be taken as indicative of future trends, as well

as trends in the rest of world. France, for example, obtains

more than half of its electricity from nuclear power, despite

the safety problems. And many believe that nuclear power

should be an important part of energy production in the

United States as well. Proponents of nuclear power argue

that its dangers have been greatly exaggerated in this country.

998

The risks, they argue, must be compared with the health

and environmental hazards of other fuels, particularly

fos-

sil fuels

In 1999, the U.S. Department of Energy announced

a new initiative called Generation IV. Designed to generate

interest and scientific research in nuclear power advances,

the program set out the following goals for the next genera-

tion (i.e., generation IV) of nuclear power plants: 1) highly

economical; 2) enhanced safety; 3) sustainable with minimal

waste; and 4) commercially viable by 2025. Ten countries,

including the United States, United Kingdom, Canada,

South Africa, and Japan, were participating in the Genera-

tion IV International Forum (GIF) as of early 2002. One

of the most promising prototypes reactor designers have

come up with is the gas-cooled pebble-bed reactor, which

uses a non-reactive helium coolant and operates more effi-

ciently and at less cost than current water-cooled systems.

For some, hope for the future of nuclear power rests

with the development of

nuclear fusion

. A nuclear power

plant based on a fusion reaction would amount to a controlled

Environmental Encyclopedia 3

Nuclear Regulatory Commission

version of a

hydrogen

bomb, just as conventional nuclear

plants are equivalent to a controlled version of an atomic

bomb. But the problem of managing the reaction is far more

difficult with fusion than it is with fission, and scientists

have been working on this issue unsuccessfully for more

than 40 years. Some believe that a fusion power plant could

become a reality in the next century, but many now doubt

that such a plant will ever be feasible.

[David E. Newton and Paula Anne Ford-Martin]

ESOURCES

OOKS

Cheney, Glenn A. Journey to Chernobyl: Encounters in a Radioactive Zone.

Chicago: Academy Chicago Pub, 1995.

Garwin, Richard L. and Georges Charpak. Megawatts and Megatons: A

Turning Point in the Nuclear Age. New York: Knopf, 2001.

Hodgson, Peter. Nuclear Power, Energy, and the Environment. London:

World Scientific Publishing, 1999.

Wilpert, Bernard, et al., eds. Safety Culture in Nuclear Power Organizations.

London: Taylor & Francis, 2001.

ERIODICALS

Lake, James et al. “Next-Generation Nuclear Power.” Scientific American

286, no. 1 (January 2002): 72(8).

THER

Union of Concerned Scientists. Briefing: Nuclear Reactor Security. [cited

July 2002]. <http://www.ucsusa.org/energy/br_safenplants.html>.

U.S. Department of Energy, Office of Nuclear Energy, Science, and Tech-

nology. Generation IV: The Future of Nuclear Power. [cited July 2002].

<http://gen-iv.ne.doe.gov>.

RGANIZATIONS

Sandia National Laboratories: Energy and Critical Infrastructure, PO Box

5800, Albuquerque, NM USA 87185 (505) 284-5200, <http://

www.sandia.gov>.

U.S. Nuclear Regulatory Commission, Office of Public Affairs (OPA),

Washington, DC USA 20555 (301) 415-8200, Toll Free: (800) 368-5642,

Email: opa@nrc.gov, <http://http://www.nrc.gov>.

Nuclear Regulatory Commission

The development of

nuclear weapons

during World War

II raised a number of difficult nonmilitary questions for the

United States. Most scientists and many politicians realized

that the technology used in weapons research had the poten-

tial for use in a variety of peacetime applications. In fact,

research on techniques for controlling

nuclear fission

for

the production of electricity was well under way before the

end of the war.

An intense Congressional debate over the regulation

commercial

nuclear power

resulted in the creation in 1946

of the

Atomic Energy Commission

(AEC). The AEC had

two major functions: to support and promote the develop-

999

ment of nuclear power in the United States and to monitor

and regulate the applications of nuclear power.

Some critics pointed out early on that these two func-

tions were inherently in conflict. How could the AEC act

as a vigorous protector of the public safety, they asked, if it

also had to encourage industry growth? The validity of that

argument did not become totally obvious for nearly two

decades. It was not until the early 1970s that the suppression

of information about safety hazards from existing plants by

the AEC became public knowledge.

The release of this information prompted Congress

and the President to rethink the government’s role in nuclear

power issues. The result of that process was the

Energy

Reorganization Act

of 1973 and Executive Order 11834

of January 15, 1975. These two actions established two new

governmental agencies, the Nuclear Regulatory Commission

(NRC) and the Energy Research and Development Agency

(ERDA). NRC was assigned all of AEC’s old regulatory

responsibilities, while ERDA assumed its energy develop-

ment functions.

The mission of the Nuclear Regulatory Commission

is to ensure that the civilian uses of nuclear materials and

facilities are conducted in a manner consistent with public

health and safety, environmental quality, national security,

and anti-trust laws. The single most important task of the

commission is to regulate the use of nuclear energy in the

generation of electric power.

In order to carry out this mission, the commission has

a number of specific functions. It is responsible for inspecting

and licensing every aspect of nuclear power plant construc-

tion and operation, from initial plans through actual con-

struction and operation to disposal of

radioactive waste

materials. The commission also contracts for research on

issues involving the commercial use of nuclear power and

holds public hearings on any topics involving the use of

nuclear power. An important ongoing NRC effort is to

establish safety standards for nuclear

radiation exposure

A fair amount of criticism is still directed at the Nu-

clear Regulatory Commission. Critics feel that the NRC has

not been an effective watchdog for the public in the area of

nuclear safety. For example, the investigation of the 1979

Three Mile Island Nuclear Reactor

accident found that the

commission was either unaware of existing safety problems

at the plant or failed to inform the public adequately about

these problems.

[David E. Newton]

ESOURCES

RGANIZATIONS

U.S. Nuclear Regulatory Commission, Office of Public Affairs,

Washington, D.C. USA 20555 (301) 415-8200, Toll Free: (800) 368-

5642, Email: opa@nrc.gov, <http://www.nrc.gov>

Environmental Encyclopedia 3

Nuclear test ban

The Comprehensive Test Ban Treaty (CTBT), which pro-

hibits all nuclear explosions either for military or “peaceful”

purposes, was adopted by the United Nations General As-

sembly in September 1996. Although disputes remain in

some countries over the ratification of the treaty, the adop-

tion of the text by the General Assembly marks the culmina-

tion of several decades of intermittent negotiation aimed at

the worldwide prohibition of nuclear explosions within the

United Nations nuclear nonproliferation framework. The

CTBT aims at preventing the development and proliferation

nuclear weapons

and is viewed by the United Nations

as an important step toward eventual nuclear disarmament.

President Dwight D. Eisenhower first suggested a ban

on atmospheric testing in 1955, but it was not until August

1963, in the aftermath of the 1962 superpower showdown

over the stationing of nuclear-capable missiles in Cuba, that

the United States and the U.S.S.R. agreed to a Partial Test

Ban Treaty (PTBT). This agreement banned all atmospheric

tests of nuclear weapons, but allowed both parties to set off

explosions in the more frequently-used underground tests.

With both superpowers concerned about issues of sover-

eignty and espionage, the PTBT limited procedures for veri-

fication of compliance to what were called “national technical

means,” which consisted mainly of satellite, communica-

tions, and long-distance seismic monitoring. While the

PTBT’s overall impact on arms control is generally thought

to have been negligible, it did serve to prevent a great deal

pollution

of the

atmosphere

and the Earth’s surface by

plutonium

and other radioactive substances.

In 1974, the PTBT was supplemented by the signing

of a Threshold Test Ban Treaty (TTBT) that limited the

explosive yield of underground nuclear tests. Initially, the

TTBT also relied on national technical means for verifica-

tion. But in 1990, the original protocol was replaced with

a new agreement on verification means that allowed for on-

site inspections and in-country seismic monitoring.

Fourteen years after the adoption of the PTBT, the

United States, U.S.S.R., and United Kingdom convened

trilateral talks aimed at achieving a comprehensive test ban.

Some limited progress was made toward resolving several

points of disagreement, but in general the parties achieved

few tangible results in these negotiations. This lack of success

combined with a general toughening of United States policy

towards the U.S.S.R. after the 1980 elections to all but end

discussion of a test ban treaty.

Against the wishes of both the United States and the

United Kingdom, a series of amendments was suggested in

January 1991, under the authority of the existing treaties’

revision procedures. A conference of the nuclear powers

was convened to consider the proposed amendments. These

1000

negotiations were inconclusive, but they did signal consider-

able international interest in a comprehensive ban. Political

momentum toward this end was given a boost in 1992, when

Russia, France, and the United States declared a nine-month

moratorium on all testing. In doing so, the United States

reversed official doctrine introduced in the 1980s, which

held that testing via explosions was a necessary component of

national security. The radical geopolitical changes associated

with the disintegration of the U.S.S.R. also played a role in

changing the climate of negotiations. As a result, the 1994

Conference on Disarmament created a committee with a

mandate to establish a framework for a comprehensive ban.

By extending its own moratorium on nuclear tests, the Clin-

ton Administration signaled its willingness to sign the re-

sulting CTBT, giving the final process of negotiation an

important boost.

Technological and political developments, however,

are already raising new issues for arms control experts and

negotiators. Advances in communications and surveillance

technology aid the verification of compliance. But advances

in nuclear physics and weapons technology, such as the

advent of so-called micro-nukes and hydronuclear tests with

greatly reduced yields, make the very definition of nuclear

testing problematic. Several countries, especially India and

Pakistan, have expressed strong misgivings about the CTBT.

Although the United States strongly supports the treaty on

an official level, substantial and deep-rooted opposition to

the CTBT persists, including some notable critics among

those charged with oversight of its huge nuclear arsenal.

Opponents of the treaty argue that limited testing is neces-

sary for checking the safety and reliability of existing nuclear

warheads and for maintaining the credibility of the nuclear

deterrent.

[Lawrence J. Biskowski]

Nuclear waste

see

Radioactive waste

Nuclear weapons

There are two types of nuclear weapons, each of which

utilizes a different nuclear reaction:

nuclear fission

and

nuclear fusion

. The bomb developed by the Manhattan

Project and dropped on Japan during World War II were

fission weapons, also known as atomic bombs.

Hydrogen

bombs are fusion weapons, and these were first developed

and produced during the early 1950s.

In fission weapons, the explosive energy is derived

from nuclear fission, in which large atomic nuclei are split

into two roughly equal parts. Every time a nucleus divides,

Environmental Encyclopedia 3

Nuclear weapons

it releases a large amount of energy. Each fission reaction

also produces one or more neutrons, the subatomic particles

that are needed to initiate a fission reaction. Thus, once a

fission reaction has been started in a few nuclei, it rapidly

spreads to other nuclei around it, creating a

chain reaction

The two nuclei most commonly used for this type of nuclear

reaction are uranium-235 and plutonium-239.

The necessary fission reaction will not occur if an

atomic bomb carries any single piece of fissionable material

that is more than a few kilograms. The bomb can contain

more than one piece of this size, but it seldom contains

more than three or four. Thus there is a limit to the size of

a fission weapon, as well as the energy it can release. Nuclear

weapons and the force of their blasts are measured in kilo-

tons, each of which is equivalent to a thousand tons of TNT.

Fission weapons are limited to 20 or 30 kilotons.

Fusion weapons derive their explosive power from a

reaction that is the opposite of fission. In fusion, two small

nuclei combine or fuse, releasing large amounts of energy

in the process. The materials needed to initiate another

fusion reaction are produced as a byproduct. Fusion, like

fission, is a cyclic reaction.

In contrast to fission weapons, a hydrogen bomb can

be of almost any size. Such a bomb consists of a fission

bomb at the core, surrounded by a mass of hydrogen isotopes

used in the fusion reactions. No limit exists to the mass of

hydrogen that can be used, and there is thus no theoretical

limit to the size of fusion weapons. The practical limit is

simply the necessity of transporting it to a target; the bomb

cannot be so large that a rocket or an airplane is unable to

carry it effectively. Both fission and fusion weapons are often

classified as strategic or tactical. Strategic weapons are long-

range weapons intended primarily for attack on enemy land.

Tactical weapons are designed for use on the battlefield, and

their destructive power is adjusted for their shorter range.

Nuclear weapons cause destruction in a number of

different ways. They create temperatures upon explosion

that are, at least initially, millions of degrees hot. Some of

their first effects are heat effects, and materials are often

incinerated on contact. The heat from the blast also causes

rapid expansion of air, resulting in very high winds that can

blow over buildings and other structures. A weapon blast

also releases high levels of radiation, such as neutrons, x

rays, and gamma rays. Humans and other animals close to

the center of the blast suffer illness and death from

radiation

exposure

. The set of symptoms associated with such expo-

sure is known as

radiation sickness

. Many individuals who

survive radiation sickness eventually develop

cancer

and

their offspring frequently suffer genetic damage. Finally, a

weapon’s blast releases huge amounts of radioactive materi-

als. Some of these materials settle out of the

atmosphere

almost immediately, creating widespread contamination.

1001

Others remain in the atmosphere for weeks or months,

resulting in long-term

radioactive fallout

Because of their destructive power, the nations of the

world have been trying for many years to reach agreements on

limiting the manufacture and possession of nuclear weapons.

Between July 16, 1945, and September 23, 1992, the United

States of America conducted (by official count) 1054 nuclear

tests, and two nuclear attacks. In 1963, the United States

and the former Soviet Union agreed to a Limited Nuclear

Test Ban Treaty that banned explosions in the atmosphere,

outer space, and underwater. After 1963, both nations con-

tinued testing underground. The 1974 Threshold Test Ban

Treaty restricted the underground testing of nuclear weapons

by the United States and the former Soviet Union to yields

no greater than 150 kilotons.

In the 1980s and 1990s, debates over arms control

and continued testing of nuclear weapons were affected by

a number of international developments. The first was the

growing internal weakness and eventual disintegration of

the former Soviet Union. After a decade of difficult negotia-

tions, the United States and the Soviet Union signed a

bilateral Strategic Arms Reduction Agreement, or START

I, on July 31, 1991. Five months later the Soviet Union

dissolved. It was succeeded by four states that had nuclear

weapons on their territories: Russia, the Ukraine, Belarus,

and Kazakhstan. On December 5, 2001, the United States

and the Russian Federation succeeded in reducing their

number of deployed warheads to the level specified by

START I. The Ukraine, Belarus, and Kazakhstan have elim-

inated or removed from their territory all nuclear weapons

left over from the Soviet period. The START II treaty,

which specifies further reductions in the number of nuclear

weapons possessed by both powers, was ratified by the U.S.

Senate on January 26, 1996, and by the Russian Duma on

April 14, 2000. On May 24, 2002, President George W.

Bush of the United States and President Vladimir Putin of

Russia signed the Strategic Offensive Reductions Treaty,

which commits both nations to reduce the number of their

nuclear warheads to two-thirds of their 2002 levels by De-

cember 31, 2012.

The second international development of concern has

been the steady increase in the number of states possessing

nuclear weapons, and the potential for their use in interna-

tional conflicts. As of the spring of 2002, the Carnegie

Institute’s Non-Proliferation Project estimates that 35 na-

tions have some type of nuclear ballistic missile. It is difficult

to obtain precise information about the number and location

of these weapons because many countries in the so-called

“nuclear club” have not openly acknowledged their mem-

bership.

The third development since the 1980s is the growing

possibility that terrorist groups might acquire the informa-

Environmental Encyclopedia 3

Nuclear winter

tion and materials to build nuclear devices. This fear acquired

new prominence after the terrorist attacks of September 11,

2001. As early as 1997 Alexander Lebed, a Russian general,

claimed that the former Soviet Union had developed nuclear

weapons small enough to fit in a suitcase. Although technical

information is lacking on the Russian side, the United States’

experimental development of small-sized nuclear weapons

suggests that it is technically possible to design a bomb small

enough to fit in a large suitcase. In addition, it is known

that members of al-Qaeda made several attempts to purchase

commercial reactor-grade

plutonium

during the 1990s. As

of 2002, however, the likelihood of a terrorist group’s con-

structing a small portable nuclear device is not high. The

construction of a suitcase bomb using plutonium would re-

quire a very high degree of sophistication, and would be

extremely hazardous to its creators. On the other hand, there

are no substantial technical obstacles for a small terrorist

group to manufacture a simple but highly destructive nuclear

bomb about the size of a truck. One scientific expert has

stated, “There is no doubt that if a group like al-Qaeda were

to obtain sufficient fissile material—no more than 12 kg of

plutonium, or 50 kg of highly enriched

uranium

, and quite

possibly less—a highly destructive [nuclear] bomb could be

constructed.”

[Rebecca J. Frey Ph.D.]

ESOURCES

OOKS

Dresser, P. D., ed. Nuclear Power Plants Worldwide. Detroit, MI: Gale

Research, 1993.

Jagger, J. The Nuclear Lion: What Every Citizen Should Know about Nuclear

Power and Nuclear War. New York: Plenum, 1991.

Weinburg, A. M. Continuing the Nuclear Dialogue. La Grange Park, IL:

American Nuclear Society, 1985.

ERIODICALS

Ahearne, J. F. “Nuclear Power after Chernobyl.” Science (May 8, 1987):

673–79.

THER

National Academy of Sciences, Committee on International Security and

Arms Control. The Future of U.S. Nuclear Weapons Policy. Washington,

DC: National Academy Press, 1997.

Robinson, C. Paul. A White Paper: Pursuing a New Nuclear Weapons Policy

for the Twenty-First Century. Albuquerque, NM: Sandia National Labora-

tories, 2002.

Sublette, Carey. “Could Al-Qaeda Go Nuclear?” EnviroWeb. May 18, 2002

[cited July 11, 2002]. <http://www.nuketesting.enviroweb.org>.

RGANIZATIONS

Federation of American Scientists, 1717 K Street, NW, Suite 209,

Washington, DC USA 20036 (202) 546-3300, <www.fas.org>.

National Nuclear Security Administration, Sandia National Laboratories,

New Mexico, P. O. Box 5800, Albuquerque, NM USA 87185 (925) 294-

3000, <www.sandia.gov>.

1002

Nuclear weapons testing

see

Bikini atoll; Nevada Test Site

Nuclear winter

Nuclear winter is a term given to what would happen to

Earth’s

environment

following a large-scale nuclear war.

In effect, the entire planet would be plunged into a very

bitter winter that would last months or years. The most

severe consequence would be that Earth’s

climate

would

become too cold to grow vital food crops, including rice,

wheat, and corn. It would likely lead to the starvation of

hundreds of millions of people who survived the initial nu-

clear blasts. In effect, it would likely be the end of civilization.

However, with the end of the Cold War and the

breakup of the Soviet Union, the threat of a full-scale nuclear

exchange between the United States and Russia has greatly

diminished. Today, the term nuclear winter is also used to

describe the aftermath of any event that sends huge amounts

particulate

matter into the

atmosphere

, blocking the

sun and drastically cooling Earth’s atmosphere. Such events

could include the simultaneous eruption of a number of large

volcanoes, or the impact upon the planet of a large comet

or asteroid.

Although eight countries are known to possess

nu-

clear weapons

as of 2002, it was the thousands of warheads

held by the United States and Russia that most worried

scientists during the Cold War. A nuclear exchange between

other countries, such as India and Pakistan, would not create

a nuclear winter because most of the world’s croplands would

be spared.

Many of the horrible consequences of a global nuclear

conflict have been well known for nearly half a century.

Though much research has been conducted in this area,

there is still much to be learned. Many scientists believe that

the

smoke

produced as a result of a nuclear conflict would

reduce the transmission of sunlight to Earth’s surface over

a significant portion of the planet. According to the theory,

this reduction in sunlight would then cause a cooling on

land surfaces of anywhere from 18–65°F (10–35°C). Interior

parts of a continent would experience greater cooling than

would coastal regions. Some parts of the planet that now

experience a temperate climate might be plunged into win-

ter-like conditions.

The idea of nuclear winter has been controversial ever

since it was first proposed in 1983 by famed astronomer

Carl Sagan (1934–1996). The U.S.

National Academy of

Sciences

, the U.S. Office of Science and Technology Policy,

the World Meteorological Organization, the International

Council of Scientific Unions, and the

Scientific Committee

on Problems of the Environment

, as well as dozens of

Environmental Encyclopedia 3

Nutrient

individual scientists, have analyzed the potential for a nuclear

winter and the problems that it might engender. These

studies have not resolved the many issues surrounding a

possible nuclear winter effect, but they have clarified a num-

ber of factors involved in that effect.

First, the fundamental logic behind a possible nuclear

winter effect has been considerably strengthened. Experts

estimate that about 9,000 teragrams (9 trillion grams) of

finished lumber exist in the world. A large portion of that

is found in urban areas that are likely to be the focus of a

nuclear attack. By one estimate, anywhere from 25–75% of

the wood in an urban area would be ignited in a nuclear

attack. A second resource vulnerable to nuclear attack is

the world’s

petroleum

reserves. Most experts agree that oil

refineries, oil storage centers, and other concentrations of

oil deposits would be likely targets in a nuclear attack. These

materials would also serve as fuel in a widespread fire storm.

The main product of concern in the

combustion

wood, petroleum, and other materials (

plastics

, tar, asphalt,

vegetation, etc.) would be sooty smoke. This smoke would

decrease solar radiation by as much as 50%. In addition, it

would not easily be washed out of the atmosphere by rain,

snow, and other forms of precipitation. Computer models

have also shown that soot in the atmosphere may be more

stable than first imagined. Studies also suggest that a nuclear

winter effect could produce serious consequences for the

ozone

layer. One effect would be the dislocation of the

ozone layer over the Northern Hemisphere towards the

Southern Hemisphere. Another effect would involve actual

destruction of the ozone layer by

nitrogen

oxide molecules

carried aloft by smoke.

Scientists have studied a number of natural phenomena

with nuclear winter-like effects. Volcanic eruptions, massive

forest fires, natural dust clouds, urban fires, and extensive

wild fires all produce massive amounts of smoke similar to

what would be expected in a nuclear conflict. For example,

massive wildfires in China during May of 1987 were found

to reduce daytime temperatures in Alaska by 4–12°F (2–

6°C) in ensuing months. Possible climatic effects from the

enormous oil well fires during the

Persian Gulf War

,as

well as recent volcanic eruptions, are also being studied. One

scientist studying this phenomenon has said, however, that

“severe environmental anomalies—possible leading to more

human casualties globally than the direct effects of nuclear

war—would be not just a remote possibility, but a likely

outcome.”

A number of scientists have challenged Sagan’s find-

ings, saying he overestimated the devastation that would

result from a large-scale nuclear war. Several scientists sug-

gested the result of such a war would be a “nuclear fall” rather

than nuclear winter. While this would also be a disaster,

the scientists suggested that it would not mean the end of

1003

civilization as Sagan predicted. The scientists explained that

this is because Sagan greatly overestimated both the amount

of smoke and dust that would be created and its duration

in the atmosphere.

[Ken R. Wells]

ESOURCES

OOKS

Sagan, Carl, and Richard Turco. A Path Where No Man Thought: Nuclear

Winter and the End of the Arms Race.New York: Random House, 1990.

ERIODICALS

Marshall, Eliot. “Nuclear Winter Debate Heats Up.” Science (January 16,

1987): 271–274.

Overbye, D. “Prophet of the Cold and Dark.” Discover (January 1985):

24–32.

Seitz, Russell. “An Incomplete Obituary.” Forbes (February 10, 1997):

123–124.

Sinberg, Stan. “Springtime for Nuclear Winter.” Omni (April 1992): 98–99.

Turco, R. P., et al. “Climate and Smoke: An Appraisal of Nuclear Winter.”

Science (January 12, 1990): 166–167.

RGANIZATIONS

Manchester University Computing Society, Oxford Road, Room G33,

Manchester, Great Britain M13 9PL 44(0)161-275-7329, Email: admin@

compsoc.man.ac.uk, <http://www.compsoc.man.ac.uk/~samp/nuclearage/

effect.html>

Nucleic acid

Nucleic acids are macromolecules composed of polymerized

nucleotides. Nucleotides, in turn, are structured of phos-

phoric

acid

, pentose sugars, and organic bases. Deoxyribo-

nucleic acid (DNA) most commonly exists as a double

stranded helix. The genetic information of some viruses,

bacteria, and all higher organisms is encoded in DNA, and

the physical basis of heredity of these organisms is dependent

upon the molecular structure of DNA.

DNA is transcribed into single stranded

ribonucleic

acid

(RNA), which is then translated into protein. The

conversion of the genetic information of a

species

into the

fabric of that organism involves several kinds of RNA, viz.,

messenger RNA (mRNA), transfer RNAs (tRNA), and ri-

bosomal RNAs (rRNA). The genetic material of some vi-

ruses is RNA.

Nutrient

All plants and animals require certain

chemicals

for growth

and survival. These chemicals are called biogenic salts or

nutrients (from the Latin word nutrio meaning to feed, rear,

or nourish). They can be categorized as those needed in

large amounts called macronutrients, and those needed in

Environmental Encyclopedia 3

Nutrient

minute amounts called micronutrients or trace elements.

Macronutrients include

nitrogen

(an essential building

block of chlorophyll and protein),

phosphorus

(used to

make DNA and ATP), calcium (a component of cell walls

and bones), sulfur (a component of amino acids), and magne-

sium (a component of bones and chlorophyll). Micronutri-

ents, although needed only in trace amounts, are still essential

for survival. Examples include cobalt (used in the synthesis of

1004

vitamin B

), iron (essential for

photosynthesis

and blood

respiratory pigment), and sodium (used in the maintenance

of proper acid-based balance called osmoregulation, nerve

transmission, and several other functions). Some micronutri-

ents, such as

copper

and zinc, can be harmful in large

amounts. The borderline between necessary and excessive is

often narrow and varies among

species

Oak Ridge, Tennessee

Along with towns such as Los Alamos, New Mexico, and

the area around the Savannah River in Georgia, Oak Ridge

is central to the history of the development of

nuclear

weapons

in the United States. It has also come to represent

many of the environmental consequences of nuclear research

and weapons production.

Oak Ridge was a small, sleepy town when it was se-

lected as a research site in the 1940s for the development

of the atomic bomb. Amidst an

atmosphere

of intense

secrecy, the government built the Oak Ridge National Labo-

ratories within a period of months and assembled a force of

75,000 scientists. These physicists, engineers, and others

worked under extreme security to design various components

of the

hydrogen

bomb. Their research was carried out under

the auspices of the Manhattan Project, though the tasks

were compartmentalized and few scientists are thought to

have been aware of the larger significance of their work.

After the end of World War II, the laboratories at

Oak Ridge were used for the research activities and weapons

production of the Cold War. Although the area did experi-

ence decreases in the number of highly trained personnel,

the research center remained an important part of the gov-

ernment’s network of national laboratories. During this pe-

riod, the

U.S. Department of Energy

(DOE) took over the

management of the Oak Ridge laboratories and subcon-

tracted administrative operations to such private corpora-

tions as Union Carbide and the Martin Marietta Corpora-

tion. Peacetime activities also included major research and

educational initiatives developed in association with the local

university.

Because of the urgency and secrecy under which mili-

tary research was conducted at Oak Ridge, little attention

was paid to the health impacts of radiation or the safe dis-

posal of

hazardous waste

. Starting in 1951, the research

facilities were responsible for storing 2.7 million gallons

(10.2 million liters) of concentrated acids and radioactive

wastes in open ponds. 76,000 rusting barrels and drums

1005

containing mixed radioactive wastes remained on the site.

Millions of cubic yards of toxic and

radioactive waste

were

also buried in the ground with no containment precautions.

2.4 million pounds (1 million kg) of

mercury

and an un-

known amount of

uranium

are estimated to have been re-

leased into the ambient

environment

through the air, water

and

soil

pathways. The DOE has spent $1.5 billion evaluat-

ing the level of contamination and planning

remediation

and treatment activities, and that figure is expected to grow

exponentially. Cleanup programs are now the focus of much

of the research done by the nuclear scientists at Oak Ridge.

Vegetation and

wildlife

(water fleas,

frogs

and deer)

around the laboratories have set off high readings of

radioactivity

in Geiger counters.

Radionuclides

such as

strontium, tritium and

plutonium

have been traced in

surface waters 40 miles (64 km) downstream of the plant.

However, few published studies exist on human health

effects from hazardous waste disposal in the area. Studies

that examined short term

cancer

rates in the male worker

population found no correlation between cancer risk and

worker

radiation exposure

; these studies also noted that

Oak Ridge employees were actually 20% less likely to die

from cancer as the rest of the country—a fact which may

be due to the quality of their medical care. Yet studies

that followed the health patterns of workers over a period

of 40 years documented that cancer risk did indeed increase

by 5% with each rem of increasing radiation exposure.

These studies also found that white male workers at the

laboratories had a 63% higher

leukemia

death rate than

the national average.

In 1977 large amounts of employee health records

were deliberately destroyed at the Oak Ridge National Labo-

ratories, and the DOE has attempted to influence the inter-

pretation and publication of health studies on the effects of

radiation exposure. These facts raise troubling questions for

many about the level of knowledge at the research center of

the effects of low-level radiation. Both the laboratories and

the town itself are considered case studies of the environmen-

Environmental Encyclopedia 3

Occupational Safety and Health Act (1970)

tal problems that can be caused by large federal facilities

operating under the protection of national security.

[Douglas Smith]

ESOURCES

ERIODICALS

“Low-Level Radiation: Higher Long-Term Risk?” Science News 139 (March

23, 1991): 181.

Thompson, D. “Living Happily Near a Nuclear Trash Heap.” Time 139

(May 11, 1992): 53–54.

Occupational Safety and Health Act

(1970)

The Occupational Safety and Health Act (1970) was in-

tended to reduce the incidence of personal injuries, illness,

and deaths as a result of employment. It requires employers

to provide each of their employees with a workplace that is

free from recognized hazards, which may cause death or

serious physical harm. The act directed the creation of the

Occupational Safety and Health Administration

(OSHA) within the U. S. Department of Labor. This agency

is responsible for developing and promulgating safety and

health standards, issuing regulations, conducting inspec-

tions, and issuing citations as well as proposing fines for

violations. See also Right-to-act legislation

Occupational Safety and Health

Administration

The Occupational Safety and Health Administration

(OSHA) was established pursuant to the

Occupational

Safety and Health Act

(1970). Within the Department of

Labor, OSHA has the responsibility for occupational safety

and health activities pursuant to the Act which covers virtu-

ally every employer in the country except all types of mines

which are regulated separately under the Mine Safety and

Health Act (1977). The Occupational Safety and Health

Administration develops and promulgates standards, devel-

ops and issues regulations, conducts inspections to insure

compliance, and issues citations and proposes penalties. In

the case of a disagreement over the results of safety and

health inspections performed by OSHA, employers have the

right of appeal to the Occupational Safety and Health Re-

view Commission, which works to ensure the timely and

fair resolution of these cases.

1006

ESOURCES

RGANIZATIONS

U.S. Department of Labor, Occupational Safety & Health Administration,

200 Constitution Avenue, Washington, D.C. USA 20210 Toll Free: (800)

321-OSHA, <http://www.osha.gov>

Ocean Conservatory, The

“The will to understand, conserve, and protect ocean life is

at the very core of the Ocean Conservatory’s mission. To

fulfill this mission, the Ocean Conservatory seeks to: protect

marine ecosystems, prevent

marine pollution

, protect en-

dangered marine

species

, manage fisheries for

conserva-

tion

, and conserve marine biodiversity.” Since its founding

in 1972, the Ocean Conservatory (formerly the Center for

Marine Conservation) has worked toward these goals. The

endangered species

the group helps to protect include,

among many others,

whales

dolphins

, seabirds,

seals and

sea lions

, and

sea turtles

Over 110,000 Ocean Conservatory members nation-

wide volunteer their time in many different ways, including

writing to Congress asking for support of marine conserva-

tion, and organizing or participating in beach cleanups across

the country. In 1988, for example, more than 16,000 people

took part in beach cleanups in Florida and Texas. This

number grew and in 2000, 850,000 people cleaned over

20,000 mi (32,187 km) of coast. More than 100 countries

have helped the United States in this effort to clean the

beaches.

Because of human actions and the ever-changing

envi-

ronment

, the Ocean Conservatory’s goals constantly grow

and change. Over the years they have challenged formidable

opponents, including Exxon. After the

Exxon Valdez

oil

spill, the Ocean Conservatory participated in the cleanup

and forced Exxon to step up the rescue and rehabilitation

of sea otters (Enhydra lutris) and other mammals and birds

injured by the accident.

Another important Ocean Conservatory activity is the

Marine

Habitat

Program. Through this program, the Ocean

Conservatory has played a pivotal role in establishing six

marine sanctuaries in the United States (there are only eight

total), as well as in other countries. One of these, the Silver

Back Humpback Whale Sanctuary, protects humpback

whales (Megaptera novaeangliae) near the Dominican Re-

public. Established in 1986, it was the world’s first whale

sanctuary.

Research is an important component of all Ocean

Conservatory programs. The group’s ongoing research and

advocacy has resulted in the adoption of stricter regulations

on commercial

whaling

by the International Whaling Com-

mission. The Ocean Conservatory has also helped to pass

federal and state regulations requiring the use of turtle ex-