Click on a decade or an image above for details after 1940s.

July 14, 1942: In the midst of World War II, the United States secretly undertook the Manhattan Project to develop an atomic bomb before the Germans.

December 2, 1942: The first self-sustaining nuclear chain reaction occurs at the University of Chicago under the guidance of physicist Enrico Fermi.

July 16, 1945: The U.S. conducts the world's first nuclear test explosion near Alamogordo, New Mexico. Called the "Trinity" test, it explodes with a force equivalent to 18,000 tons of TNT.

August 6, 1945: U.S. nuclear program becomes public with the bombing of Hiroshima and Nagasaki, substantially contributing to the end of World War II.

October 24, 1945: The United Nations Charter entered into force, founding the new international organization. Yet the good intentions of this new peacekeeping organization were threatened by the onset of the Cold War. At the first meeting, the U.S. delegate proposed a plan to internationalize control of atomic energy. The plan was rejected by the Soviet Union.

August 1, 1946: President Truman signs the Atomic Energy Act (AEA), establishing the Atomic Energy Commission (AEC). The AEC replaces the Manhattan Project, regulating nuclear weapons, nuclear testing and peacetime applications like nuclear power. The AEA places further development of nuclear technology under civilian (not military) control.

October 6, 1947: The AEC first investigates the possibility of peaceful uses of atomic energy, issuing a report the following year.

March 1, 1949: The AEC announces the selection of a site in Idaho for the National Reactor Testing Station.

August 29, 1949: The first Soviet Atomic bomb is exploded in Kazakhstan, ending the U.S. monopoly of the weapon.

January 31, 1950: President Truman announces his decision to develop the hydrogen bomb.

1951: U.S. government begins above-ground testing of nuclear bombs at the Nevada Test Site. Thousands of Utahns and Nevadans are exposed to high levels of radioactive fallout during a dozen years of open air testing. Many cancer victims will point to the fallout as causing their illness.

December 20, 1951: The first electric power from nuclear energy is produced, lighting four light bulbs.

November 1, 1952: The U.S. successfully tests the first hydrogen bomb at Eniwetok Atoll in the Pacific.

August 12, 1953: The U.S.S.R. tests its first thermonuclear weapon.

December 1953: President Eisenhower delivers his "Atoms for Peace" speech before the United Nations. He calls for greater international cooperation in the development of atomic energy for peaceful purposes.

January 1954: The U.S. Navy launched the first nuclear-powered submarine, the Nautilus.

1954: Nuclear weapons programs result in a rush for uranium ore, turning Moab, Monticello and Blanding, Utah into boomtowns. Boom lasts several years, tapering off in the 1960s as military stockpiles are filled.

August 30, 1954: President Eisenhower signs The Atomic Energy Act of 1954, the first major amendment of the original Atomic Energy Act, giving the civilian nuclear power program further access to nuclear technology.

January 10, 1955: The AEC announces the Power Demonstration Reactor Program. Under the program, AEC and industry will cooperate in constructing and operating experimental nuclear power reactors.

July 17, 1955: Arco, Idaho, population 1,000, becomes the first town powered by a nuclear power plant.

November 22, 1955: First Soviet thermonuclear bomb is dropped in Kazakhstan.

March 1956: U.S. explains its opposition to nuclear disarmament at UN stating that atomic weapons are a "powerful deterrent to war."

July 12, 1957: The first power from a civilian nuclear unit is generated by the Sodium Reactor Experiment at Santa Susana, California. The unit provided power until 1966.

September 2, 1957: The Price-Anderson Act provides for federal responsibility and financial assurances to the public and AEC licensees and contractors if a major accident occurs at a nuclear power plant.

October 1, 1957: The United Nations creates the International Atomic Energy Agency (IAEA) to promote the peaceful use of nuclear energy and prevent the spread of nuclear weapons.

October 4, 1957: Soviets launch Sputnik, fueling Cold War hysteria and an escalation in the demand for uranium needed for nuclear weapons.

December 2, 1957: The world's first large-scale nuclear power plant begins operation in Shippingport, Pennsylvania. The plant reaches full power three weeks later and supplies electricity to the Pittsburgh area.

October 15, 1959: Dresden-1 Nuclear Power Station in Illinois, the first U.S. nuclear plant built entirely without government funding, achieves a self-sustaining nuclear reaction.

Early 1960s: Small nuclear power generators are first used in remote areas to power weather stations and to light buoys for sea navigation.

August 13, 1961: Cold War reaches its height with the construction of the Berlin Wall, and the Cuban Missile Crisis in 1962.

November 22, 1961: The U.S. Navy commissions the world's largest ship, the U.S.S. Enterprise, a nuclear-powered aircraft carrier.

October 10, 1963: World's superpowers agree to ban aboveground nuclear tests with the Limited Nuclear Test Ban Treaty, but underground tests would continue into the 1990s.

December 12, 1963: Jersey Central Power and Light Company announces its plan for the Oyster Creek nuclear power plant, the first time a nuclear plant is ordered as an economic alternative to a fossil fuel plant.

August 16, 1964: President Lyndon Johnson signs the Private Ownership of Special Nuclear Materials Act, which allows the nuclear power industry to own the fuel for its units. After June 30, 1973, private ownership of the uranium fuel is mandatory.

April 3, 1965: The first nuclear reactor in space is launched by the United States.

March 5, 1970: The United States, United Kingdom, Soviet Union, and 45 other nations ratify the Treaty for Nonproliferation of Nuclear Weapons.

April 1970: The U.S. and U.S.S.R open Strategic Arms Limitation Talks (SALT).

1970: The U.S. increased the pace of the nuclear arms race with the deployment of Minuteman III, the first missiles with multiple independently targetable reentry vehicles (MIRVs), which made it possible to target many cities with nuclear weapons from a single missile.

1971: Twenty-two commercial nuclear power plants are in full operation in the United States. They produce 2.4 percent of U.S. electricity at this time.

1972: The SALT I accords are signed, placing limits on the number of offensive armaments which each side could possess. The Antiballistic Missile (ABM) Treaty, designed to halt a defensive nuclear arms race, was also signed.

1973: U.S. utilities order 41 nuclear power plants, a one-year record.

June 1973: The U.S. and Soviet Union entered into an agreement on the Prevention of Nuclear War, agreeing to "remove the danger of nuclear war and the use of nuclear weapons." Should the risk of nuclear war arise, the nations promised to enter into "urgent consultations."

1974: The first 1,000-megawatt-electric nuclear power plant goes into service - Commonwealth Edison's Zion 1 Plant.

October 11, 1974: The Energy Reorganization Act of 1974 divides AEC functions between two new agencies - the Energy Research and Development Administration (ERDA), to carry out research and development, and the Nuclear Regulatory Commission (NRC), to regulate nuclear power.

April 7, 1977: President Jimmy Carter announces the United States will defer indefinitely plans for reprocessing spent nuclear fuel. Also viewed as the "recycling" of the spent fuel rods associated with nuclear power plants, the decision has a profound impact on the amount of nuclear waste to be stored by the nation's utilities.

August 4, 1977: President Carter signs the Department of Energy Organization Act, which transfers ERDA functions to the new Department of Energy (DOE).

1979: Utah's first hazardous waste dump is started at Grassy Mountain, Tooele County, by Khosrow Semnani, who soon sells the facility to U.S.PCI. Today, it is known as Safety Kleen, which has filed for bankruptcy protection.

March, 1979: The worst accident in U.S. commercial reactor history occurs at the Three Mile Island nuclear power station near Harrisburg, Pennsylvania. The accident is caused by a loss of coolant from the reactor core due to a combination of mechanical malfunction and human error. Later in the year, the NRC imposes stricter reactor safety regulations and more rigid inspection procedures to improve the safety of reactor operations.

1979: Seventy-two licensed reactors generate 12 percent of the electricity produced commercially in the United States.

March 26, 1980: DOE initiates the Three Mile Island research and development program to develop technology for disassembling and de-fueling the damaged reactor. The program will continue for 10 years and make significant advances in developing new nuclear safety technology.

January 7, 1983: The Nuclear Waste Policy Act (NWPA) establishes a program to site a repository for the disposal of high-level radioactive waste, including spent fuel from nuclear power plants. It also establishes fees for owners and generators of radioactive waste and spent fuel, who pay the costs of the program.

1983: Nuclear power generates more electricity than natural gas.

1984: The atom overtakes hydropower to become the second largest source of electricity, after coal. Eighty-three nuclear power reactors provide about 14 percent of the electricity produced in the United States.

1986: The Perry Power Plant in Ohio becomes the 100th U.S. nuclear power plant in operation.

April 26, 1986: Operator error causes two explosions at the Chernobyl No. 4 nuclear power plant in the former Soviet Union. The reactor has an inadequate containment building, and large amounts of radiation escape, exposing hundreds of thousands of people to dangerously high levels of radiation.

September 1987: The U.S. and Soviet Union agree to establish Nuclear Risk Reduction Centers in both countries to reduce the risks of accidental nuclear war.

December 1987: The U.S. and Soviet Union sign the Intermediate-range Nuclear Forces (INF) Treaty, agreeing to remove these weapons from Europe.

December 22, 1987: The Nuclear Waste Policy Act (NWPA) is amended. Congress directs DOE to study only the potential of the Yucca Mountain, Nevada site for disposal of high-level radioactive waste. In the same timeframe, the Department of Energy begins examining creation of a large "temporary" storage site for nuclear waste. The Department actively encourages communities and Native American tribes to apply for DOE grants to further study hosting such a facility.

1988: U.S. electricity demand is 50 percent higher than in 1973.

1988: Cleanup of the defunct Vitro uranium mill in South Salt Lake is completed, marking a surge in interest by a variety of waste companies in building waste dumps in Tooele County. In response to state initiatives, Tooele County commissioners create a hazardous waste zone in Utah's West Desert. The area lies just beyond Skull Valley and the borders of the Dugway Proving Ground. Commissioners state that hazardous wastes, properly managed, can be viewed as sound economic development.

1988: Khosrow B. Semnani buys state lands around the stored Vitro tailings. Envirocare Inc. becomes the nation's only commercial waste dump for the low-level radioactive wastes, mostly mill tailings left over from Cold War-era industry and military testing programs.

1989: The United States now claims 109 nuclear power plants producing 19 percent of the electricity used in the U.S.; 46 units have entered service during the decade.

April 18, 1989: The NRC proposes a plan for reactor design certification, early site permits, and combined construction and operating licenses.

1990: Congress passes the Radioactive Exposure Compensation Act to compensate downwinders and uranium mine and mill workers harmed by radiation. Congress expanded compensation to additional miners and mill workers in 2001.

1990: America's 110 nuclear power plants set a record for the amount of electricity generated, surpassing all fuel sources combined in 1956.

April 19, 1990: The final shipment of damaged fuel from the Three Mile Island nuclear power plant arrives at a DOE facility in Idaho for research and interim storage. This ends the DOE's 10-year research and development program.

1991: One hundred and eleven nuclear power plants operate in the United States with a combined capacity of 99,673 megawatts. They produce almost 22 percent of the electricity generated commercially in the United States.

July 1991: The United States and Soviet Union sign historic agreement to cut back long-range nuclear weapons by more than 30 percent over the next seven years.

1991: The first hazardous waste incinerator is completed in Utah's West Desert. Today known as the Safety Kleen plant at Aragonite.

1992: The nation's nuclear power plants account for nearly 22 percent of all electricity used in the U.S.

February 26, 1992: DOE signs a cooperative agreement with the nuclear industry to co-fund the development of standard designs for advanced light-water reactors.

1992: The Energy Policy Act of 1992 is signed into law. The Act makes several important changes in the licensing process for nuclear power plants.

March 30, 1993: The U.S. nuclear utility consortium, the Advanced Reactor Corporation (ARC), signs a contract with Westinghouse Electric Corporation to perform engineering work for an advanced, standardized 600-megawatt pressurized-water reactor. Funding for this next-generation plant comes from ARC, Westinghouse, and DOE.

September 6, 1993: The U.S. nuclear utility consortium, ARC, signs a contract with General Electric Company for cost-shared, detailed engineering of a standardized design for a large, advanced nuclear power plant. The engineering is being funded under a joint program among utilities, General Electric, and DOE.

Early-1990s: The Department of Energy program examining creation of a large "temporary" nuclear waste storage facility is shut down. Dozens of communities and Native American tribes had applied for study grants. In 1993 the Skull Valley Band of the Goshute Indian tribe considered itself very close to signing an agreement with DOE to host such a facility, only to have the program terminated.

1994-1995: Nuclear power utilities begin forming associations to consider creation of a privately owned nuclear waste storage site. Negotiations are initiated with the Mescalero Apache tribe of New Mexico, and the Skull Valley Band of Goshutes in Utah.

1995: The Mescalero Apaches stage a tribal referendum and vote against hosting a temporary nuclear waste storage project. When efforts to revive the plan fail among the Mescaleros, the Skull Valley Band of Goshutes remain the only actively-negotiating Native American tribe interested in hosting a nuclear waste storage site.

1996: Utah Governor Michael Leavitt announces strong opposition to the siting of a temporary nuclear waste storage site in his state. Leavitt tells leaders of the Skull Valley Band of Goshutes that such a project would only go forward "over my dead body."

May 20, 1997: The Skull Valley Band of Goshute Indians sign a lease with Private Fuel Storage, L.L.C. to temporarily store 40,000 tons of nuclear waste on tribal lands for up to 40 years.

2000: Congress agrees to clean up a small mountain of uranium waste at the Atlas mill site near the banks of the Colorado River outside Moab, Utah. The site is the last major mill on the Colorado River to be cleaned up.

2001: Envirocare petitions Utah Legislature and governor to allow it to store higher levels of radioactive wastes than it is currently licensed to accept at its Tooele County storage facility.

January 2001: The Utah State Legislature enacts several bills aimed at delaying or discouraging the creation of the Private Fuel Storage project on the Skull Valley reservation. However, a bill to provide compensating economic development funds for the Goshutes is defeated in the last hours of the legislative session.

May 2001: The Department of Energy certifies that the Yucca Mountain location in Nevada meets scientific standards to serve as a permanent nuclear waste repository. The certification must be endorsed by the President and ratified by Congress. Private Fuel Storage says a 2010 "earliest possible" opening for a permanent repository means their proposed temporary project in Skull Valley remains viable and will move ahead.

May 2001: Actions in the courts:

• Eighteen members of the Skull Valley Band file suit in federal district court seeking to block the proposed nuclear waste storage project, claiming a range of regulatory and financial improprieties.
• Private Fuel Storage joins with the tribal council of the Skull Valley Band of Goshutes to file suit in federal court against the State of Utah, seeking to overturn recently enacted laws which are targeted at the project.

July 11, 2001: KUED-TV presents "Skull Valley". . .a documentary examining the political, economic, social and cultural conflicts involved in the proposal to store nuclear waste in Utah.

2001: The Nuclear Regulatory Commission is expected to complete its Environmental Impact Statement on the proposed Skull Valley facility. Final field hearings will be held later in the year.

2002: The Nuclear Regulatory Commission has set the Spring of 2002 as a target date for a final decision on licensing the proposed temporary nuclear waste storage facility proposed by Private Fuel Storage for the Skull Valley reservation.

Late Spring 2002: A consortium of nuclear power utilities hopes to begin construction of a high-level nuclear waste facility on Goshute lands about 80 miles southwest of Salt Lake City. First shipments of waste could arrive via railroad as early as 2003.