A secondary engineering challenge for nuclear power production has been the safe handling and long-term storage of the dangerously radioactive products resulting from nuclear fission. The fission of a uranium nucleus results in two new lesser nuclei, of roughly half the weight of the original nucleus. These newly formed elements are always neutron heavy, having more neutrons than would normally be found in the nuclei. To reach a natural equilibrium, the new elements must decay radioactively, convert­ing excess neutrons to protons or occasionally ejecting delayed fission neu­trons. Powerful gamma rays result as the changing nuclear structures settle into the new equilibrium. The length of time for this process depends entirely on the species of new elements that are made by a given fission and vary over a wide range. The half-life, or time required for half of the radio­activity to decay away, can vary from microseconds to thousands of years. Having a short half-life means that a radioactive element, or radionuclide, will be extremely radioactive, but it will decay quickly. Having a long half­life means that a radionuclide will be slightly radioactive but long-lived.

The most radioactive waste products have decayed away six min­utes after fission. Iodine-131 and barium-140 are gone after four months. Cerium-141, zirconium-95, and strontium-90 take two or three years to disappear, and cerium-144, ruthenium-106, and promethium-147 linger for more than 10 years. Strontium-90 and cesium-137 are the most persis­tent and possibly dangerous fission products, each with a half-life of 30 years. Compared with the volume of waste produced by any combustion process, such as burning coal, the bulk of fission products is miniscule. If all the electrical power that a person consumes in a lifetime were pro­duced by nuclear fission, then the waste product from that production would fit in a Coke can and weigh 2.0 pounds (0.9 kilograms). If that elec­tricity were produced by burning coal, the solid waste would be a small mountain weighing 68.5 tons (62.1 mt) and the gaseous carbon dioxide would weigh 77 tons (70 metric tons).

At the dawn of the nuclear era during World War II, hazardous nuclear waste from A-bomb production was dumped in the ocean, stored tempo­rarily in liquid form in underground tanks, or simply allowed to dissipate into the atmosphere. Risky nuclear facilities for research, fuel or isotope production, or open-air tests were purposefully placed in low-habitation areas. When nuclear power became a privately owned, commercial prod­uct, the management of waste products had to become a priority, to be controlled and regulated by the federal government. In 1957, the National Academy of Sciences, after careful study and consideration, recommended that the best way to dispose of nuclear waste was to bury it in rock, deep underground.

In 1970, President Richard M. Nixon (1913-94) proposed the Environ­mental Protection Agency (EPA) to protect human health and safeguard the natural environment. Nixon signed this new agency into being on December 2, 1970, and an Office of Air and Radiation was opened. Under the subject of hazardous waste, the Nuclear Waste Repository Act, PL 97-425, was signed in 1982, taking responsibility for the long-term storage of nuclear power by-products.

President Gerald R. Ford (1913-2006) formally abolished the AEC in 1974. The AEC had been in charge of both promoting nuclear power and controlling nuclear power simultaneously, and this had long been seen as a conflict of interest. The commission was broken into two new agen­cies, the Energy Research and Development Agency (ERDA), for promo­tion, and the Nuclear Regulatory Commission (NRC), for control. The NRC would write the rules and regulations for spent-fuel storage, and the ERDA would oversee research into the implementation of the tasks.

In 1977, in a proposal from President Jimmy Carter, the Department of Energy Organization Act, PL 95-91, dismantled ERDA and replaced it with the Department of Energy (DOE). Radioactive waste disposal was clearly specified as a primary DOE responsibility. A Waste Isolation Pilot Plant (WIPP) had been in planning and design since 1974. After more than 20 years of scientific study, regulatory actions, and public debate, WIPP began operation on March 26, 1999.

WIPP is located 2,150 feet (655 m) underground, approximately 26 miles (42 km) east of Carlsbad, New Mexico. Radioactive waste is stored

in rooms excavated out of the Salado and Castile Salt Formations. Storing waste in salt is considered ideal, because the formation has been stable and free of any moisture for 250 million years. Because there is no water

in a salt formation, nothing will dissolve and leak into the drinking water. If any cracks develop in a room made of salt, the plastic characteristic of the material will cause it to flow and fill any gap.

Although it is planned to hold only the radioactive waste from nuclear weapons production and not spent fuel from power reactors, the pilot plant is considered an excellent test of engineering and construction con­cepts for long-term storage. The facility is expected to continue accepting waste canisters until 2070. After it is sealed, radioactive monitoring will continue for another 100 years.

In 2028, a final plan will be submitted to the DOE for marking the site as a warning to future explorations. Warnings in seven languages will be etched into the floor of a large granite room over the portal. Pictographs showing a person screaming are also considered.

A permanent storage facility for spent reactor fuel was in development in the 1970s, but there is more to the task of radioactive waste. There must be a way to transport the spent fuel from power plants located all over the country to a central repository. Special, crash — and fireproof shipping casks were developed by the DOE, tested, and judged against 10 CFR 71 and the International Atomic Energy Agency standards, Regulations for the Safe Transport of Radioactive Material. The requirements are strict. A shipping cask must be strong enough to remain intact after one-hour immersion under 655 feet (200 m) of water, a 30-minute fire at 1,475°F (800°C), and a 30-foot (9-m) drop onto an unyielding surface. The NRC further requires that shipments follow only approved routes, have armed escorts, and notify in advance the states through which a fuel shipment will pass.

For two years, the DOE subjected spent fuel shipping casks to every form of train wreck, truck accident, and hostile action imaginable, and none of these tests resulted in a leaking container. More than 3,000 ship­ments of spent reactor fuel have been safely transported in the United States, as reactors have been shut down and dismantled. Canada has simi­lar safety requirements for safe spent fuel shipping, as does the United Kingdom. British Nuclear Fuels Limited has transported more than 14,000 casks of spent fuel over rail, road, and water for Great Britain, Japan, and continental Europe.

With the transportation problem solved, Congress established a national policy to build an underground storage facility for spent fuel in the Nuclear Waste Policy Act in 1982. Yucca Mountain, a ridgeline in Nevada 80 miles (129 km) northwest of Las Vegas, was studied as an ideal location for deep storage since 1978. It is in a federally owned desert with

no habitation. Starting with a thorough investigation of the area’s geology, the DOE began design work for the spent fuel facility. On July 23, 2002, President George W. Bush (1946- ) signed House Joint Resolution 87,

allowing the DOE to apply for a construction license with the NRC.

In its final design, the Yucca Mountain Nuclear Waste Repository will hold 300 million pounds (136 million kg) of spent reactor fuel. The project has cost $9 billion, and the expense is borne by a tax on each kilowatt of power generated by nuclear means. The facility is scheduled to be com­pleted in 2017, but its future is presently on hold. The state of Nevada has decided that nuclear waste from all over the country should not be buried there. Other countries, such as Japan, France, and the Netherlands, have also established their own long-term spent-fuel storage strategies, but the Yucca Mountain Repository is probably the largest and the most contro­versial in the world.