Permissible doses, radiation

Figure 5 Thermal history of a chondrule (sohd fines) passing through a 7.5 km s shock wave, over timescales of (a) hours and (b) minutes. Chondrules are heated for hours before the shock by radiation. At the shock front, chondrules must slow to the gas velocity in 1 min it takes to do so, gas drag heating causes a spike in temperature. Afterwards, chondrules are heated for hours by radiation and thermal exchange with the hot gas (dashed line) (Desch and Connolly, 2002) (reproduced by permission of Sheridan Press and Meteoritical Society from Meteorit.

For the theoretical treatment of the mutual interaction between radiation and matter it is permissible, by KirchhofE s principle, to replace the actual atoms of the substances by simple models, so long as these do not contradict any of the known laws of nature. The... 

The International Commission on Radiological Protection (ICRP) recommends specific limits of dose, applicable to stated time intervals (a quarter, a year, and so forth) as guidance for protection of radiation workers these are called maximum permissible doses and are applicable to individuals exposed continuously or intermittently from time to time as their work requires (40). To assist the planning of nuclear designs and operations so as to minimize, appropriately, the low level exposure of members of the public which may ordinarily result from normal operations, dose limits for individual members of the public are recommended by ICRP which are one-tenth or less of the maximum permissible doses for radiation workers. Though these maximum permissible doses and dose limits have little to do directly with the control of major radiation emergencies (i.e., reactor accidents) they are quoted in brief in Table VII. 

Figure 8.6 U V-vis-NIR spectra of solutions of Janus Green B azo dye in NMP (A), and aqueous acidic solution (B), and resonance Raman spectra of Janus Green B azo dye in the solid state obtained at the indicated exciting radiations. The dye molecular structure is also shown. (Reprinted with permission from Macromolecules, Aniline Polymerization into Montmorillonite Clay A Spectroscopic Investigation of the Intercalated Conducting Polymer by G. M. do Nascimento, V. R. L. Constantino, R. Landers and M. L. A. Temperini, 37, 25. Copyright (2004) American Chemical Society)...

The performance of a diagnostic X-ray machine should be checked at least annually with appropriate instruments by a qualified person. If the capability to do this is not available in-house, a qualified consultant should be hired to do the task. If any maintenance is done or if the machine is relocated, a survey should be undertaken for leakage radiation fromthe source. If the unit is moved to another facility, the exposure levels in the adjacent areas should be tested to ensure that the exposure levels are within the permissible limits forcontrolled and uncontrolled areas. Records of all maintenance, surveys, leakage checks, calibration, personnel monitoring, etc. should be maintained at the facility and at the radiation safety office. Because of the long latency period for cancer developing from radiation exposures, it would not be unreasonable to maintain personnel exposure records for up to 40 years. 

When the entire beam path from a Class IIIB or Class IV laser is not sufficiently enclosed or baffled to ensure that radiation exposures do not exceed the maximum permissible exposure, a laser-controlled area is required. During periods of service, a controlled area may be established on a temporary basis. Two controls are required for both Class IIIB and Class IV installations (1) posting with appropriate laser warning signs, and (2) operated by qualified and authorized personnel. 

Eisenhower s announcement failed to quiet the debate over radiation problems because new recommendations of the National Committee on Radiation Protection soon produced another controversy. The issue stemmed from a decision of the International Commission on Radiological Protection, made public in early 1959, to advise a maximum permissible level for whole-population exposure firom internal emitters of one-hundredth of the occupational limit for gonad-seeking radioisotopes and one-thirtieth of the occupational limit for radioisotopes that do not affect the reproductive cells. Most internal emitters, including strontium 90, cause somatic rather than genetic damage. The action of the ICRP... 

Plate 52 Laser optical bench system used as an excitation source for a Raman spectrometer. Raman spectroscopy provides essentially the same sort of information about molecular structure and dimensions as do infrared and microwave spectroscopy. The laser is an ideal Raman source it provides a narrow, highly mono-chromatic beam of radiation which may be focused accurately into small smaple. See Raman Spectrometers FT-Raman Spectroscopy, Applications Industrial Applications of IR and Raman Spectroscopy Polymer Application of IR and Raman Spectroscopy IR and Raman Spectroscopy of Inorganic, Coordination and Organometallic Compounds. Reproduced with permission from Science Photo Library. 

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