Exposure to radiation

This approach has the advantage of reducing the number of process upsets that must be examined. In a nuclear plant, the hazard has one location - the core a chemical plant, hazards have many locations. In a nuclear plant, the hazard is exposure to radiation and fission products in a... 

The accident reportedly killed 31 people, injured 299 others, and caused tlic evacuation of 135,000 from the site. The full extent of tlie damage from tliis incident probably will not be known for years. It is tlie long-term effects from exposure to radiation that frighten most people, and tliese fears may still become a horrible reality. 

Irene Curie and Frederic Joliot received the Nobel Prize in physics. The award came too late for Irene s mother, who had died of leukemia in 1934. Twenty-two years later. Irene Curie-Joliot died of the same disease. Both women acquired leukemia through prolonged exposure to radiation. 

Human exposure to radiation is monitored by reporting the absorbed dose and... 

A dosimeter is used to collect cumulative evidence of exposure to radiation and is worn as a badge. Dosimeters contain a thermoluminescent material such as lithium fluoride. Any incident radiation knocks electrons out of the flu-... 

Radioisotopes have important commercial applications. For example, americium-241 is used in smoke detectors. Its role is to ionize any smoke particles, which then allow a current to flow and set off the alarm. Exposure to radiation is also used to sterilize food and inhibit the sprouting of potatoes. Radioisotopes that give off a lot of energy as heat are also used to provide power in remote locations, where refueling of generators is not possible. Unmanned spacecraft, such as Voyager 2, are powered by radiation from plutonium. 

Polymer films that are sensitive to light, x-rays, or electrons— known as photoresists—are nsed extensively to transfer the pattern of an electronic circuit onto a semiconductor surface. Such films must adhere to the semiconductor surface, cross-link or decompose on exposure to radiation, and nndergo development in a solvent to achieve pattern definition. Virtually all aspects of photoresist processing involve surface and interfacial phenomena, and there are many outstanding problems where these phenomena mnst be controlled. For example, the fabrication of multilayer circuits requires that photoresist films of about 1-pm thickness be laid down over a semiconductor surface that has already been patterned in preceding steps. 

Some polymers like PE and NR get cross-linked on exposure to radiation while others like those based on vinylidene polymers, e.g., polymethylmethacrylate (PMMA), polyisobutylene, degrade. Certain other types of polymer stmctures (high aromatic content or thermoset) resist degradation by high-energy radiation. Coating polymers usually contain acrylic, methacryUc, or fumaric vinyl unsaturation along or attached to the backbone. 

Performance requirements, environmental issues, and avaUabUity/cost of the material will mainly drive material requirement in the future. In order to face the huge tire wastage problem causing major hazards to the environment, future development in mbbery materials will be focused on development of thermoplastic polymer so that used polymer could be recovered by thermal treatment and separation, biological degradation by radiation/addition of chemical into the mbber compound that could be activated by exposure to radiation and development of biopolymer. 

Because exposure to radiation is a health risk, the administration of radioactive isotopes must be monitored and controlled carefully. Isotopes that emit alpha or beta particles are not used for Imaging, because these radiations cause substantial tissue damage. Specificity for a target organ is essential so that the amount of radioactive material can be kept as low as possible. In addition, an Isotope for medical Imaging must have a decay rate that is slow enough to allow time to make and administer the tracer compound, yet fast enough rid the body of radioactivity in as short a time as possible. 

Radioactivity also Is used to treat certain diseases. Some cancers respond particularly well to radiation therapy. Radioactivity must be used with care, because exposure to radiation damages healthy cells and eventually causes cancer. The key to radiation therapy is that cancer cells reproduce more rapidly than normal cells, and rapidly reproducing cells are more sensitive to radiation. If concentrated doses of radiation are focused on the malignant cells, a cancer may be destroyed with minimal damage to healthy tissue. Nevertheless, radiation therapy always has unpleasant side effects, including nausea and hair loss. 

The nuclear explosions that devastated Hiroshima and Nagasaki killed 100,000 to 200,000 people instantaneously. Probably an equal number died later, victims of the radiation released in those explosions. Millions of people were exposed to the radioactivity released by the accident at the Chernobyl nuclear power plant. The full health effects of that accident may never be known, but 31 people died of radiation sickness within a few weeks of the accident, and more than 2000 people have developed thyroid cancer through exposure to radioactive iodine released in the accident. Even low levels of radiation can cause health problems. For this reason, workers in facilities that use radioisotopes monitor their exposure to radiation continually, and they must be rotated to other duties if their total exposure exceeds prescribed levels. 

Living cells are delicately balanced chemical machines. The ionization track generated by a nuclear particle upsets this balance, almost always destroying the cell in the process. Although the body has a remarkable ability to repair and replace damaged cells, exposure to radiation can overload these control mechanisms, causing weakness, illness, and even death. 

Exposure to low doses of radiation causes no short-term damage but makes the body more susceptible to cancers. In particular, people who have been exposed to increased radiation levels have a much higher incidence of leukemia than the general population has. Marie Curie, the discoverer of radium, eventually died of leukemia brought on by exposure to radiation in the course of her experiments. Medical researchers estimate that about 10% of all cancers are caused by exposure to high-energy radiation. 

C22-0078. Why does exposure to radiation in cancer therapy result in nausea and reduced resistance to infection ... 

Radiation sterilization Radiochromic chemical Plastic devices impregnated with radiosensitive chemicals which undergo colour changes at relatively low radiation doses Only indicate exposure to radiation... 

Although chromosomal aberrations have been reported in lymphocytes following exposure to 241Am (Bauchinger et al. 1997 Kelly and Dagle 1974), and these observations are consistent with the effects of exposure to radiation, these effects are not specific to radioactive americium or to ionizing radiation in general. 

Cumulative Dose (Radiation)—The total dose resulting from repeated or continuous exposures to radiation. 

Characterizing the radiation dose to persons as a result of exposure to radiation is a complex issue. It is difficult to (1) measure internally the amount of energy actually transferred to an organic material and to correlate any observed effects with this energy deposition and (2) account for and predict secondary processes, such as collision effects or biologically triggered effects, that are an indirect consequence of the primary interaction event. 

The knockout of PARP-1 or PARP-2 significantly reduces the cells ability to repair damaged DNA following their exposure to radiation or cytotoxic insult [6,7]. Poly (ADP-ribose) polymer synthesis consumes substantial amounts of NAD+, and hyperactivation of PARP results in depletion of cellular NAD+ pools and energy stores, leading to cell death by necrosis. 

The average annual effective dose equivalent received by a member of the UK population is currently estimated to be 2150 ySv. Of this total, 87% arises from exposure to radiation of natural origin, the largest single contributor being inhalation of the short-lived decay products of radon. This exposure occurs predominantly in the home. 

NEA Nuclear Energy Agency Group of Experts, Exposure to Radiation from the Natural Radioactivity in Building Materials, OECD Nuclear Energy Agency, Paris (1979). 

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