Radiation from varied sources

TABLE S.3.8.6 Estimated Absorbed Doses of Radiation from Varied Sources ... 

Sound power is the total energy emitted from a fan that is a function of the fan s speed and point of operation and is independent of the fan s installation and surrounding environment Sound power level is the acoustical power expressed in decibels (dB) radiating from a source. Sound power can be converted into predictable pressure levels (dBA) after the acoustical environment surrounding the fan is defined. Sound pressure for a specific fan varies with... 

Example 10-2 Everyone has poked a campfire at night and watched the sparks fly up. They glow a bright red, which indicates that they are emitting blackbody radiation from a source with a surface temperature of -1200°C. You have also noticed (if you were thinking about scientific matters at the time) that their color does not change until they suddenly disappear. The time for this reaction varies, but they seem to glow for a few SdC and then suddenly disappear. 

Radiation is regarded by many people with special fear. Of course, everyone encounters radiation from many sources throughout life and there is radiation in our own bodies, from outer space and from our surroundings, with which our bodies appear to cope extremely well. The background levels vary considerably from place to place, but the records do not show any correlation between the incidents of radiation-related diseases (cancer and leukaemia) and the level of background radiation. All nuclear plants involve some release of radioactive material, but the effect on the environment corresponds to a very small fraction of the normal background, even near the plant. The effect of radiation depends on its intensity, duration and type and the age, food and living habits of individuals. 

The JIMO spacecraft would be subjected to radiations from two sources during its Journey through space the internal radiations generated by SNPP reactor and the external radiations generated by the stellar and planetary objects in space. The SNPP reactor would subject the remainder of the spacecraft to a continuous stream of neutron and gamma radiations at nearly constant levels for the duration of the mission, while space sources would impinge on the spacecraft in varying forms, rates, and intensities. It is the electrical and electronic systems aboard the spacecraft that would be particularly vulnerable to these radiations and that are the focus of the considerations herein. 

The reactor for radiation chemical synthesis with an agitator (about 200 rotations per minute) is located in the operation chamber. Inside the reactor there is a cavity for introducing sources of y-radiation. The role of the radiation source is played by 60Co in airproof stainless steel ampules the activity of 60Co radiation is about 3000 eq Ra. The consumption degree of the energy of radiation when the sources are placed in the cavity, or the radiation coefficient of efficiency, varies from 17 to 19%. The equipment is encased in a special box made of stainless steel and plexiglass the box has intensive ventilation. 

A significant concern in the use of total radiation pyrometry is that it must be calibrated at the distance it will be from the source because of the influence of the atmosphere. Normal atmosphere contains a small fraction of carbon dioxide and water vapor (the latter dependent on the relative humidity, which varies with the day). When combustion is used for furnace heating (e.g. CH4+2O2 = 2H2O+CO2), water vapor and carbon dioxide are the predominant, atmospheric constituents. As... 

We are all exposed to radiation on a daily basis from both natural and man-made sources. Background radiation levels vary widely depending on altitude, local geology, and latitude, but average background radiation dose in the United States and Canada is about 360 milli-rem (mrem) annually. Of this, nearly 300 mrem is due... 

In all, we receive about 360 mrem/yr from background sources of radiation a dose that varies considerably in both directions depending on local geology, elevation, and other factors. It is worth noting that, even in areas with exceptionally high levels of natural radiation, inhabitants do not appear to suffer from any ill effects. This suggests that occupational exposure to moderately elevated radiation levels is not harmful. 

Note how the intensity of the radiation varies with the distance from the source. The unit of radiation intensity is millirem per second per square meter. (This is the amount of radiation striking a square meter of area each second.) Use the graph to answer the Thinking Critically questions that follow. 

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