26 August 2011

Nuclear waste

Nuclear waste, also called radioactive waste, is produced by nuclear power plants or other facilities or vehicles that contain a nuclear reactor, factories that process nuclear fuels or materials such as uranium, and some research and medical institutions. Nuclear waste is a by-product of nuclear materials used to generate electricity, diagnose and treat disease, build weapons, and power ships, as well as of other nuclear-related activities. Nuclear waste is often hazardous and is strictly regulated by the government.



Nuclear waste, also called radioactive waste, is produced by nuclear power plants or other facilities or vehicles that contain a nuclear reactor, factories that process nuclear fuels or materials such as uranium, and some research and medical institutions. Nuclear waste is a by-product of nuclear materials used to generate electricity, diagnose and treat disease, build weapons, and power ships, as well as of other nuclear-related activities. Nuclear waste is often hazardous and is strictly regulated by the government.

Nuclear waste is radioactive. Radiation describes the process by which a body emits energy that travels through space and is absorbed by another body. Ionizing radiation displaces the electrons in atoms, which can cause damage to cells. Radioactivity can cause damage by being directly absorbed by tissues or by being ingested, inhaled, or injected.

Examples of ionizing radiation are alpha (a helium nucleus), beta (an energetic electron), gamma (high-energy photons), and x-rays (photons with somewhat less energy than that of gamma radiation). Different types of ionizing radiation carry varying levels of energy and can thus penetrate different substances more or less effectively. Beta particles, for example, can penetrate paper but not aluminum, while gamma radiation may only be stopped by lead.

Radiation is measured in curies (Ci) or becquerels (Bq), both of which measure the rate of radioactive decay. Radioactive decay is the process by which an unstable nucleus emits radioactive particles, such as electrons, until the parent atom becomes stable. One becquerel equals one nuclear decay per second. One curie is equal to 37 billion disintegrations per second. The dose of radiation absorbed by human tissue is measured in rads or grays (Gy), the latter of which are SI units. The likelihood that a person will be negatively affected by radiation exposure is measured in rems or the SI unit sievert (SV). One rem is equal to 1,000 millirems (mrem). According to the Nuclear Regulatory Commission NRC, the average American receives around 360mrem of ionizing radiation annually, including 60mrem from man-made sources. A dental x-ray emits about 3mrem of radiation, and a mammogram 170mrem. Living near a nuclear power plant subjects residents to about 0.1mrem annually. Chances of acute exposure to high doses of radiation are low, for the most part; however, the probability of radioactive damage is cumulative, so restrictions have been enacted to limit exposure via medical exams or to workers who labor near nuclear materials.

Nuclear power plants use radioactive materials to generate electricity. Uranium-235 is a commonly used nuclear fuel that is incorporated into ceramic pellets. These pellets are placed in rods or other configurations to emit radiation in a controlled manner.

Once inside the nuclear reactor, the uranium atom is split by absorbing a neutron (neutral particles within the nucleus of an atom), which in turn releases more neutrons and energy in the form of radiation. These neutrons hit other uranium atoms, causing them to split, or fission, and release neutrons and more radiation. This creates a fission chain reaction. The energy released during this chain reaction is harnessed by the power plant, generally by heating water, which is used to drive turbine generators and produce electricity.

The fission reaction, in addition to producing neutrons and heat, also creates by-products. These by-products include radioactive isotopes, which are atoms of elements that have the same number of protons but different numbers of neutrons. Isotopes that are unstable decay radioactively. The faster an isotope decays, the more radiation it emits.

Cesium-137 and strontium-90 are fission by-products. They have unstable nuclei that emit high levels of radiation until they reach a stable configuration. Other by-products include plutonium and other elements that produce lower levels of radiation, which take longer to decay. Stronium-90 and cesium-137 take about 60 years to completely decay. Plutonium-239 decays in about 48,000 years.

Nuclear fuel is spent, used, or depleted when the fission process has slowed to the point when it can no longer produce enough neutrons to sustain itself and continue to generate electricity. Such fuel is still hazardous, as it remains highly radioactive. Every 12-18 months, one-fourth to one-third of the fuel in the reactor is depleted and replaced with new fuel. Depleted nuclear fuel can be disposed of or reprocessed to extract still-active material for reuse.

Fuel rods, metal tubes that are often used to contain nuclear fuel, are usually 3/4 inch wide and 12 feet long arranged in square assemblies. The assemblies house between 12 and 24 rods and are usually stored under pools of water that can hold 216-8,083 assemblies.

Research and medical institutions, as well as uranium mills that extract and concentrate uranium ore, also produce nuclear waste. Cleaning supplies, equipment, protective clothing, and other wastes can be contaminated with high or low levels of radioactive materials.

Substances such as water, concrete, lead, steel, completely depleted uranium, and other materials act as protective barriers or shields, absorbing radiation (depending on its type) and preventing it from passing through and damaging human and animal tissue.

According to the NRC, direct exposure to about 500 rems of radiation is fatal to humans and animals. Spent fuel emits 10,000 rems/hour of radiation 10 years after disposal. Indirect exposure to radiation through. For example, contaminated water, is also harmful. Radioactive materials can enter the food chain and expose a larger number of people to contamination.

Radioactive waste is divided into three classes: A, B, or C. Class A waste is less radioactive than classes B or C. Highly radioactive waste is stored in such a manner as to protect the surrounding environment and human and animal populations from exposure. It is often stored in containers made of a material, such as concrete, that will shield some of the radiation. These containers are then stored underwater or underground to provide additional protection.

As of 2007, 160,000 assemblies holding 45,000 tons of spent fuel from nuclear power plants were stored in the United States, with 156,500 assemblies stored at power plant sites, and 3,500 assemblies stored at other facilities. Together, these assemblies would cover a football field and reach 5.5 yards in height. Most assemblies are stored underwater, and less than 5% are placed in dry storage. About 7,800 assemblies of spent fuel are removed annually from nuclear reactors.

In the United States, The NRC regulates the disposal of nuclear waste produced by commercial facilities. The Department of Energy (DOE) regulates waste associated with nuclear weapons production and other research. Other agencies are also involved in the management and oversight of radioactive waste, including the U.S. Environmental Protection Agency (EPA), the U.S. Department of Transportation, and the U.S. Department of Health and Human Services.


General: The radioactivity of nuclear waste can damage living tissue. If the levels of radiation are high enough, the waste may be hazardous. Nuclear waste is produced by nuclear power plants or other facilities or vehicles that contain a nuclear reactor, factories that process nuclear fuels or materials such as uranium, and some research and medical institutions. Nuclear waste is a by-product of nuclear materials used to generate electricity, diagnose and treat disease, build weapons, and power ships, as well as other nuclear-related activities. When this waste is disposed of, it may be placed in shielded structures or underground to prevent the release of radiation into the environment. The Nuclear Regulatory Commission (NRC), as well as other government agencies, regulates the disposal of nuclear waste.

Low-level waste (LLW): Low-level waste (LLW) refers to contaminated materials that do not fall under other categorizations (such has high-level waste). LLW refers to the type of waste, not the level of radioactivity the waste contains. This type of waste usually falls into four categories: 1) protective clothing, 2) cleaning supplies, 3) equipment, and 4) medical waste. Wipes, rags, mops, residues from nuclear reactor water treatments, medical tubes, and laboratory animal carcasses are examples of LLW.

LLW is generated by several industries. For instance, medical facilities may use radioactive materials to diagnose and treat disease, while researchers may use them to examine a building for structural flaws or to date a prehistoric object, all of which may produce LLW. Nuclear power plants may also produce LLW in the form of cooling water, or in infrastructure (e.g. pipes and valves) that has become contaminated.

LLW storage: LLW is usually stored at the site of production in containers that are appropriate for shielding the amount of radioactivity emitted by the waste. The waste is disposed of as trash if the radioactive contamination decays quickly. If the radioactivity is too high to decay completely, the waste is transported to an appropriate disposal site.

LLW disposal sites: There are four disposal sites that accept low-level waste in the United States: two sites in Barnwell, South Carolina, one in Clive, Utah, and one in Richland, Washington. The Barnwell and Richland sites accept class A and C waste from a particular group of states, bound by compacts. The Barnwell site disposes of waste from Atlantic compact states, which includes Connecticut, New Jersey, and South Carolina. In the past, Barnwell has also accepted waste from Rocky Mountain and Northwest compact states. Currently, waste from the Rocky Mountain and Northwest compacts is transported to the Richland site. The site in Clive, Utah, accepts waste from all states, though only class A waste.

In 2005, the Clive site accepted the largest volume of waste (3,940,775 cubic feet), though the Barnwell site disposed of the greatest amount of radioactivity (517,693 curies). In 2005, U.S. facilities disposed of about 4 million cubic feet of waste, totaling 530,000 curies of low-level radioactive waste. In 2000, 3.3 million cubic feet of LLW was generated by commercial industries, broken down as follows: 8.2% was generated by nuclear reactors, 83.8% by industrial facilities, 0.2% from academic institutions, 7.6% from non-nuclear weapon site government sources, and the remainder was from unidentified sources.

Reprocessing waste: Waste incidental to reprocessing (WIR) is the by-product of the reprocessing of spent nuclear fuel, or fuel that can no longer sustain a chain reaction. Spent fuel contains uranium and plutonium along with other compounds; reprocessing separates out the uranium and plutonium, which can be reused as fuel. WIR has had most of its highly radioactive radionuclides (atoms with unstable nuclei) removed and does not need to be stored in a repository for high-level waste. The potential risk to the public and surrounding environment associated with the waste is evaluated by the NRC and other government agencies.

WIR sites: In the past, reprocessing of depleted fuel occurred at commercial facilities. Currently, reprocessing occurs at the U.S. Department of Energy (DOE) facilities located in Hanford, Washington, and Savannah River, South Carolina, and a commercial facility in West Valley, New York. The four WIR disposal facilities are located in Aiken, South Carolina; Idaho Falls, Idaho; Richland, Washington; and West Valley, New York.

High-level waste (HLW ) : High-level waste (HLW) is the highly radioactive uranium fuel that has been used by nuclear power plants to generate electricity. After the fuel is spent and can no longer generate electricity, it is disposed of or reprocessed. Spent fuel generally consists of uranium-235 incorporated into ceramic pellets. Currently, most spent fuel is stored at the site where it is produced. Therefore, most HLW is stored on-site at nuclear power plants or a few additional facilities. There are 55 spent fuel storage sites throughout the continental United States. HLW is mostly spent fuel, but reprocessing also accounts for some HLW. Generally, spent fuel from commercial reactors is not reprocessed; however, fuel from some government-owned reactors is reclaimed.

Spent fuel pools: Most HLW is stored in pools called spent fuel pools located at the nuclear reactor site. Spent fuel pools store HLW under at least 20 feet of water, which acts as a protective shield. The fuel is transported from the reactor core to pools via a water canal for maximum shielding. Once under the pool, rods can be reracked or consolidated to make room for more fuel.

Dry cask storage: Over time, as storage space at spent fuel pools declined, reactor sites began using dry cask storage to supplement their spent fuel storage capacity. After spent fuel is cooled in pools for at least a year, it is moved to a shielded container or cask that is filled with an inert gas (a gas that will not react with other elements) and welded closed to prevent leaks. The cask is reinforced with steel, concrete, or another substance for additional safety and stored aboveground. The casks can be oriented vertically or horizontally. Seventeen nuclear plant sites in the United States use dry cask storage.

Wet versus dry storage: Spent fuel cannot be stored in dry casks until its temperature decreases, which takes at least a year after removal from the reactor core. Therefore, all spent fuel is stored underwater when it is removed from the reactor. Although both dry and wet storage are safe methods once the temperature of the fuel decreases, they differ in terms of maintenance. Dry storage is low-maintenance, requiring few support systems and opportunities for human or equipment error. Wet storage has many systems that utilize pumps, pipes, and other mechanisms that require constant monitoring.

Uranium milling: Uranium milling is the process of extracting or concentrating uranium or thorium from mined ores. Ore is a naturally occurring compound that is mined for the metal or minerals that can be refined from it. A conventional mill is a chemical plant that extracts uranium from ore. The ore is usually crushed and then a leaching agent such as sulfuric acid is applied to extract the uranium. The process of extracting uranium produces waste or tailings that must be disposed of appropriately to prevent contamination of the environment. Most mills are currently decommissioned or are in the process of being decommissioned, meaning they are being shut down and secured by the DOE or other governmental agencies.

Uranium mill tailings: Tailings are the by-products or waste produced during uranium or thorium extraction and concentration. Such waste can take the form of a sandy residue produced during the crushing of mined uranium ore, and may often contain radium, which decays into the radioactive gas radon. This waste is placed in a pile or a cell, which is either a uranium mine pit or structure built to safely house the tailings, located near or within the uranium mill. It is covered with clay, to stop radon gas from entering the atmosphere, and with other materials, such as soil, to prevent erosion. During the uranium extraction process, a leaching agent or another liquid is applied to the uranium ore, and the waste from this process is also added to the tailings pile.

Tailings disposal sites: Whether decommissioned or active, uranium mills may house tailing piles that contain waste products from uranium extraction. According to the NRC, all conventional mills licensed by the NRC are non-operational, though one mill is expected to resume operation. These sites are located in Wyoming, New Mexico, and Nebraska. An additional eight non-NRC-regulated conventional uranium mills have tailings piles, though these facilities are also non-operational. Two mills remain functional, however, in Colorado and Utah. The Utah facility can also accept low-level waste.

Uncontrolled nuclear reactions: Nuclear reactors control the nuclear fuel's fission reactions to maintain and control the amount of energy and heat that is released. However, if every fission reaction causes an additional reaction, a self-perpetuating chain reaction may occur. In a nuclear weapon, this reaction happens so fast that it cannot be controlled, creating the immense release of energy associated with nuclear weaponry. In the instance of an uncontrolled reaction within a nuclear reactor, the heat produced may overwhelm the facility's ability to contain it, damaging the plant and releasing radiation into environment. While such events, called nuclear meltdowns, can be disastrous, they do not cause explosions as nuclear weapons do, which require a specific design and configuration to function. Modern nuclear reactor designs produce self-limiting chain reactions, meaning that the nature of the reaction itself prevents such a plant from ever racing out of control and melting down.

Another hazard associated with spent fuel is the accidental fissioning of uranium and plutonium atoms contained in waste fuel. To prevent accidental fissioning, non-reactive materials such as boron are placed in the containers with spent fuel and then carefully monitored. Spent fuel rods are also kept in assemblies that prevent them from being close enough to ignite a fission reaction. Accidental fissioning could cause an explosion (though not on the scale of an atomic weapon) that releases radiation and contaminated materials over the surrounding areas. Such material, also produced the detonation of nuclear weapons, is called nuclear fallout.


General: Currently, storage and cleanup of potentially hazardous nuclear waste is a major concern for the nuclear energy industry, local and federal governments, and the general public.

High-level waste (HLW): At the moment, high-level waste (HLW) is stored at reactor sites, since no centralized depository exists for long-term storage. Depleted fuel and other high-level waste is a potential threat to the environment and public health, as it is highly radioactive. For most high-level waste, it will take hundreds of thousands of years for the radioactive material to decay into a harmless state. Therefore, the handling and long-term storage of this type of waste presents a significant challenge.

HLW storage: It has been estimated that by 2015, all the spent fuel pools at reactor sites, where most spent fuel is stored, will be full to capacity. More reactor sites are using dry cask storage as spent fuel pools reach capacity. About 57,000 tons of spent fuel is being stored at various nuclear reactor sites. Additional dry cask storage is located at the Idaho National Environmental and Engineering Laboratory near Idaho Falls, Idaho. This is a temporary storage site for overflow HLW.

Proposed storage: The Nuclear Waste Policy Act of 1982 directed the U.S. Department of Energy (DOE) to find a suitable location, to design, and to construct a permanent storage facility for high-level waste.

In 2008, the DOE applied to the U.S. Nuclear Regulatory Commission (NRC) for a license to build a HLW repository at Yucca Mountain, Nevada. The NRC has stated that it will accept the application if the DOE demonstrates that the facility will be constructed and operated safely and within existing regulations. Some criteria for safety include keeping annual radiation exposure to below 100 millirems for the public and 5,000 millirems for people working at the repository. The containers holding the HLW must remain intact for 300-1,000 years and not contain flammable or other dangerous materials. Also, the containers must be able to be retrieved for 50 years after they are initially stored.

Yucca Mountain repository: Yucca Mountain is located 100 miles northwest of Las Vegas, Nevada, on federal land. The repository is slated to house spent fuel waste from nuclear reactors and other HLW generated during weapons development by the DOE. The repository will ultimately store 77,000 tons of HLW. According to the currently proposed plan developed by the DOE, waste will be stored in multilayered steel containers placed in underground tunnels by an automated system. The tunnels are located 1,200 feet below Yucca Mountain and 800 feet above the water table.

Uranium mining: The waste products of uranium mining and processing, or tailings, contain radioactive materials, including radium, which produces the radioactive gas radon. This radioactivity will take thousands of years to decay. Until then, tailings pose a threat to human health and the environment. Most uranium processing facilities in the United States are not in use, but the tailings disposal sites located on the premises remain a potential hazard.

Demand for uranium: Most uranium mills were shut down in the 1980s, when demand for uranium dropped due to a falloff in the construction of new reactors. However, renewed interest in nuclear power abroad led to increases in the value of uranium from 2002 to 2007, with the price jumping from $9.70 per pound to over $90 per pound, according to the NRC. This price increase has fueled interest in reopening previously decommissioned uranium facilities in the United States.

Abandoned sites: In 1978, the U.S. Congress enacted the Uranium Mill Tailings Radiation Control Act of 1978 to protect the public from radiation exposure and other public health concerns associated with uranium processing. The Act grants various government agencies control over abandoned uranium processing sites, empowering them to supervise or implement the reduction or elimination of radiation at these sites. Under this Act, the U.S. Environmental Protection Agency (EPA) can set standards for hazards (such as radioactive waste) associated with tailings disposal sites that may or may not be radioactive and thus transfer the control of these hazards to the Nuclear Regulatory Commission (NRC). Eventually, the NRC will transfer ownership of the sites to state or federal governments.

Cleanup site: The Uranium Mill Tailings Remedial Action (UMTRA) Project outlines the cleanup of tailings disposal sites, or piles, at 24 locations. These sites are no longer in use. Most sites are located in Western states, with the exception of two in Pennsylvania. In North Dakota, the waste from two processing sites was combined to create 19 tailings piles that range in size from 60,000 to 4.6 million cubic yards.

Groundwater contamination: In addition to consolidating disposal sites, the UMTRA Project also assesses water quality at tailings sites. Since it began assessment in 1991, the DOE has found groundwater contamination at most sites, though two sites did not have any. Out of thirteen sites with contaminated groundwater, eight have followed action plans set out by the DOE for groundwater cleanup.

Nuclear meltdown: A nuclear meltdown occurs when a nuclear reactor's control systems fail and the heat produced by a reactor overwhelms the facility's ability to contain it. In such instances, the reactor's highly radioactive fuel and its by-products are released into the environment. Generally, the radiation released will remain contained in the structure housing the reactor; however, in the case of the Chernobyl disaster in the former Soviet Union in 1986, the reactor had no containment structure, thus contaminating the surrounding areas. Modern nuclear reactor designs produce self-limiting chain reactions, meaning that the nature of the reaction itself prevents such a plant from ever racing out of control and melting down.

Three Mile Island accident: The Three Mile Island (TMI) accident in Pennsylvania in 1979 is the only severe nuclear meltdown in U.S. history. Although the reactor's containment structure was not breached, and large amounts of radiation were not released into the environment, the TMI accident caused sweeping changes to the operation of nuclear power plants and emergency response to such incidents. According to the NRC, the estimated dose of radiation that the 2 million people in the area were exposed to was about 1 millirem and the maximum dose for someone near the site was less than 100 millirems, both unlikely to cause any noticeable effects.

Impact of TMI: After the accident at Three Mile Island, the operation of nuclear power plants was more tightly controlled. The public's distrust of the nuclear power industry and fear of nuclear disaster also increased. TMI resulted in changes to plant operator training, plant design, communication, and an expansion of the NRC's role in plant oversight. The nuclear power industry also formed its own policing body, now called the Nuclear Energy Institute, to create a unified approach to plant regulation and safety.


General: Depending on the dose, radiation can negatively affect living tissue. If the dosage is very low, then the effect may be minimal. In this case, the body's defenses are sufficient for protecting its cells against exposure. Cells may be able to repair themselves or be replaced should they die. However, damage to DNA may not always be repairable, or might be repaired incorrectly, which can lead to disease, such as cancer. The health risk associated with radiation exposure increases dosage. The type of radiation is also a factor, some being more hazardous than others. By law, a nuclear worker in the United States can be exposed to 1,000 millirems (mrem) annually. According to the U.S. Nuclear Regulatory Commission (NRC), exposure to this amount of radiation removes 51 days from a person's life. The typical amount of radiation that the general public is exposed to (360mrem annually) removes approximately 18 days.

High radiation doses: High doses of radiation are associated with several types of cancer, including lung, esophageal, bladder, breast, and colon. Exposure to other carcinogens (cancer causing agents), diet, lack of exercise, alcohol consumption, smoking, and other factors can also contribute to cancer risk.

Acute radiation syndrome (ARS): Acute radiation syndrome (ARS) occurs when people are exposed to a large dose of radiation over a short period of time, as is the case after an atomic bomb is detonated or the containment of a nuclear reactor is breached. The criterion for ARS is exposure to a very high dose of radiation that can penetrate the internal organs over all or most of the body in a few minutes. The severity of ARS depends on the dosage level of radiation. People with ARS should immediately seek medical attention. According to the U.S. Environmental Protection Agency (EPA), it is assumed that the greater the radiation exposure, the more detrimental the effects. Some of the less severe symptoms of ARS can occur after exposure to about 60 rems of radiation.

Symptoms of ARS: A few minutes after radiation exposure, the person may experience vomiting and diarrhea. A few hours after exposure, the skin swells, itches, or becomes red, and hair loss may occur. The symptoms may be intermittent or continuous for as much as a few days after exposure. This is usually followed by a short period of apparent health, though symptoms will return and may become more serious. The person can experience seizures and coma, which can last for several months. It may take years for the skin to heal. If a person dies from ARS, it is usually due to his or her bone marrow being damaged by radiation, which results in internal bleeding and infections.

Prenatal radiation exposure: Prenatal radiation exposure is the exposure of a fetus to radiation while still in the mother's womb. Exposure can occur by radiation penetrating the mother's abdomen or by the mother ingesting or inhaling radiation and passing it to the fetus through the umbilical cord. The fetus is most sensitive to radiation exposure between two and 15 weeks of gestation.

Risks for the fetus: Radiation exposure can cause abnormalities in the growing fetus, such as stunted growth and brain defects, depending on when during the pregnancy the unborn baby is exposed. Exposed unborn babies also have a slightly increased (less than 2%) risk of developing cancer later in life.

A study examining the effects of the atomic bombs dropped on Hiroshima and Nagasaki in Japan during World War II on the surviving populations found that, regardless of the person's age at the time the bomb was dropped, radiation-associated increases in cancer rates persisted throughout life. An increased risk for many cancers, including breast, ovarian, nervous system, thyroid, liver, colon, and stomach were noted.

Limiting exposure: The U.S. Centers for Disease Control and Prevention (CDC) provides steps that people can take to protect themselves from exposure to a contaminated area. The CDC suggests that the person leaves the contaminated area immediately. His or her outer clothing should be removed and placed as far away as is possible in a sealed bag. Also, the body should be washed with warm water and soap, especially the exposed parts. Medications are taken to treat internal contamination, including potassium iodide (if the person has been exposed to radioactive iodine), which, according to the U.S. Food and Drug Administration (FDA), helps protect the thyroid gland by preventing the uptake of harmful radioactive molecules into the body.

Low radiation doses: According to the NRC, current research does not find cancer to occur following exposure to low doses of radiation (below 10,000mrem). According to the NRC, studies also do not show any adverse biological effects due nuclear industry workers' chronic radiation exposure. The NRC, however, does support the suggestion that even small increases in radiation exposure can cause an increase in cancer risk. People may be exposed to lower doses of radiation through nuclear accidents, proximity to facilities processing radioactive materials, medical tests, or through their occupation.

Nuclear accident: One study examined cancer incidence in the population surrounding the Three Mile Island nuclear power plant after an accident in 1979 at the facility caused the released of radiation into the environment. It found that there was no increased risk for cancer among the residents from 1975 to 1985. Another study investigated mortality among residents near the plant from 1979 to 1992. It found that the accident had no effect on mortality. Although an increased breast cancer risk with increasing exposure to gamma radiation was observed, the researchers concluded this is probably unrelated to the accident due to the low doses of radiation released. Gamma radiation is also naturally occurring, produced by subatomic particle interactions such as the decay of radioactive elements in the earth. Space is also a source of gamma radiation, or gamma rays, though much is generally absorbed by Earth's atmosphere. High-energy radiation is also used in medicine for imaging (x-rays).

Uranium mining: One study examining the effect of uranium mining and milling activities on local human populations found that the surface soil near uranium processing facilities, as opposed to the subsurface, was contaminated with uranium-238. Levels of lead isotopes also indicated that the area was contaminated with ore transported from outside sites. Although the local population was not found to have significantly more DNA damage than control populations, the study found that the local population's DNA repair mechanisms did not function normally. The study concluded that the local population had been exposed to a low level of contamination for many years and that health problems and risks were related to radiation exposure. Their health risks were found to be similar to those of nuclear industry workers.

Cancer mortality: One study found that uranium mining and milling did not contribute to cancer deaths in one county in Texas. For over 50 years, three uranium mills and over 40 uranium mines operated in Karnes County, Texas. These facilities could have exposed local populations to radiation contamination through the air or groundwater; however, the study found that cancer mortality rates did not increase in this county during this time. Specifically, lung, bone, kidney, and liver cancer deaths were similar for Karnes County and control counties.

One study examined a uranium mining and milling community in Colorado, where these activities had continued for 80 years. Over a period of 51 years, the study found that cancer deaths were not increased for those people living near the uranium processing facilities. The exception was lung cancer mortality among males, which was increased, though the researchers suggest that this was probably due to occupational exposure to radon and cigarette smoking among miners in the community.

Nuclear processing: One study examined how two nuclear processing facilities located three miles apart in western Pennsylvania affected cancer mortality in the surrounding population. The uranium and plutonium processing were not found to increase cancer mortality among the local population over a 45-year period.

One study investigated the effect of two facilities that process uranium and plutonium on the surrounding community. The researchers evaluated cancer incidence in the community from 1993 to 1997 and found no overall increase in cancer risk from living near the facilities, though the facilities had been operating for 40 years.

Occupational exposure: Maximum radiation dosages are regulated for workers employed in the nuclear processing or nuclear power industries to limit exposure. Recommended dosages are based on studies of people who have been exposed to high levels of radiation. According to the NRC, the maximally allowed total dose exposure both internally and externally, known as the Total Effective Dose Equivalent, is 5,000mrem per year.

One study found that leukemia mortality among workers increases as radiation dose increases and that there appears to be no risk of childhood leukemia associated with the irradiation of the father before conception.

An analysis of international mortality data on 95,673 nuclear industry workers found that there is no evidence of association between radiation exposure and cancer or other mortality. The exceptions were leukemia, associated with cumulative exposure to radiation, and multiple myeloma, a cancer of the cells of the immune system.

One study examined the effect of whole-body exposure to gamma radiation to nuclear energy workers in Russia. It found an increased risk for cancer, including leukemia, with increasing dose of gamma radiation. Exposure to plutonium was also associated with an increased risk for cancers such as lung, liver, and bone.


High-level waste (HLW): A permanent storage facility for high-level nuclear waste (HLW) does not yet exist in the United States. At the moment, hazardous waste is disposed of at the site of production. Many underwater storage facilities for highly radioactive waste are full, and the nuclear industry is relying more on aboveground dry containment units for disposing of waste. Environmental groups such as the Sierra Club support the federal government assuming responsibility for the permanent storage of high-level wastes. Currently, Yucca Mountain in Nevada is being studied as a possible disposal site for HLW. The Sierra Club recommends that additional sites be investigated and that the final site selected be independently reviewed by the National Academy of Sciences and the U.S. Geological Survey.

Low-level waste (LLW): According to the U.S. Nuclear Regulatory Commission (NRC), since July 1, 2008, institutions and agencies that use radioactive materials in 36 states have had no place to dispose of some classes of low-level waste (LLW). The NRC states that a long-term solution for this problem is needed. It proposes disposing of waste with Greater-Than-Class C (GTCC) (waste that exceeds certain limits of radiation) at the U.S. Department of Energy (DOE)'s disposal facilities, and investigating revising classification of some wastes.

Future generations: Nuclear waste containing certain types or amounts of radiation can remain a hazard for thousands of years, possibly affecting many future generations. Currently, the NRC's standard for storage of HLW in a permanent centralized depository requires keeping the waste in containers that will remain intact for as little as 300 years. Also, the risk of nuclear waste disposal sites to future populations has prompted the development of universal signage in the hope that such warnings will be understood by people in the future in spite of changes in language and custom.

Expanding nuclear energy: The rise in fossil fuel prices and concern over greenhouse gas and other emissions from coal-fired and other power plants have renewed the public's interest in nuclear energy. Building new facilities or expanding older plants is a possibility, though no solution has yet been found for the storage and containment of the nuclear waste generated by nuclear reactors and associated industries.

Demand for uranium: Due to the increasing development of nuclear power abroad, the demand for uranium has increased, driving its price up and reviving interest in uranium mining. According to the NRC, the price of uranium increased from $9.70 per pound to more than $90 per pound between 2002 and 2007. Most domestic uranium mills, however, were shut down in the 1980s, due to a drop in the construction of new reactors and a subsequent drop in the price of uranium. This price increase has fueled interest in reopening inactive or decommissioned uranium facilities.

Cleanup: According to the U.S. Environmental Protection Agency (EPA), thousands of sites contaminated with radioactivity exist in the United States. They range in size from the corner of a room to tracts of land miles in length. Cleanup of many sites has been initiated or completed, although contaminated sites throughout the country still exist. Contaminated sites are located throughout the country, including locations in Alabama, Alaska, Kentucky, New Mexico, Washington, and many other states.


This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (

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