Radionuclides analyzer

Nondestructive method (EMAA instrumental neutron activation analysis) based on the measurement of radioactivity of samples analyzed by high-resolution gamma spectrometry using the differentials of the rate of decay of the radionuclides analyzed in time [15]. NAA has several important advantages [15] ... 

As part of its Radionuclides in Food Program, the FDA determined concentrations of radionuclides in their Total Diet Study, as well as food originating from the vicinity of nuclear reactors including raw vegetables, food crops (primarily fruits), fish, and milk. While not specifically analyzed for 241Am, concentrations of... 

Several accidents in nuclear facilities have been extensively analyzed and reported. The three most widely publicized accidents were at Windscale (now known as Sellafield), United Kingdom, in 1957 Three Mile Island, Pennsylvania, in 1979 and Chernobyl, Ukraine, in 1986 (UNSCEAR 1988 Severn and Bar 1991 Eisler 1995). From the accident at Windscale about 750 trillion (T)Bq 22 TBq Cs, 3 TBq Sr, and 0.33 TBq °Sr were released and twice the amount of noble gases that were released at Chernobyl, but 2000 times less and Cs. From the Three Mile Island accident, about 2% as much noble gases and 50,000 times less than from the Chernobyl accident were released. The most abundant released radionuclides at Three Mile Island were Xe, Xe, and but the collective dose equivalent to the population during the first post-accident days was <1% of the dose accumulated from natural background radiation in a year. 

The most famous cosmogenic radionuclide is 14C (t1/2 = 5730 a), which is produced by the interaction of cosmic ray neutrons via an (n,p) reaction with nitrogen [14N(n, p)14C], whereas the radioactive decay of 14C takes place by (3 decay to form the stable 14N isotope. 14C is the most important cosmogenic radionuclide for dating (see Section 9.7.5) in archaeology and can be analyzed using isotope sensitive accelerator mass spectrometry. Extremely small isotope ratios 14C/12C = 12 in nature can be measured by means of AMS.28... 

Actinides were determined at the ultratrace level in moss samples collected from the eastern Italian Alps (1500 m a.s.l.). The frozen samples were cut into 1-2 cm sections and analyzed separately to obtain the distribution curves of the vertical concentrations. For plutonium and americium isotope analysis, 1-2 g of the samples were ashed, leached, separated with respect to analytes and analyzed by alpha spectrometry and LA-ICP-MS after the plutonium or americium had been electroplated on a stainless steel disk.23 Estimated limits of quantification of LA-ICP-MS for actinide radionuclides deposited on stainless steel plates after chemical separation are summarized in Table 9.45. For most of the long-lived radionuclides in moss samples, lower limits of determination were found at the 10 15gg 1 concentration level compared to those of a - spectrometry 23... 

The resultant aqueous phase was separated from the glass and analyzed for the element or radionuclide of interest. Paige (W) has described a leaching experiment in which the liquid is recirculated over the glass in an extraction-like apparatus,... 

The equation in this form states that in the samples analyzed the distribution of any radionuclide, A, can be expressed as a linear combination of the distribution of two species, a refractory and 137Cs. Therefore, we need to determine only refractory distribution, 137Cs distribution, and mass distribution with particle size and the distribution of all other isotopic species for which aA values are known and can be calculated. The refractory species used is 155Eu. It has a half-life of 1.811 years and two easily resolved gamma photopeaks so that its abundance as well as that of 137Cs can be determined readily by gamma spectrometry. 

The determination of the rank of a matrix is fairly simple and straight-forward. Unfortunately, the orthodox methods applied to a matrix such as A in Equation 2 give an answer which is exact mathematically but useless physically, namely that the rank of A is the number of radionuclides measured or the number of samples analyzed, whichever is less. This unfortunate result arises from presence of experimental imprecision in the elements of A. One must therefore rewrite Equation 2 in the form... 

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