PubMed · 14473887
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G MILHAUD. 1962. [Radioactive isotopes].. https://pubmed.ncbi.nlm.nih.gov/14473887/
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The MultiAgency Radiation Survey and Site Investigation Manual (MARSSIM), published in December 1997, has been used for designing final status surveys at a number of D&D sites to date. One of the more challenging aspects of the MARSSIM survey design is the strategy employed when multiple radionuclides are present, particularly in Class 1 survey units. The MARSSIM recommends that potential hot spots in a Class 1 survey unit--that could exceed the derived concentration guideline levels for small elevated areas of radioactivity (i.e., DCGL(EMC))--have a reasonably good probability of being detected. Soil sampling on a specified grid size, in conjunction with gamma radiation surface scanning, is used to obtain an adequate assurance level that these hot spots are not missed during the final status survey. Therefore, it is sometimes necessary to supplement the sample size required by the statistical test to provide additional assurance that potential hot spots of concern are detected.
Complexes of the type [Re(III)L6]X3, with L = thiourea, N-methylthiourea, N-ethylthiourea or N,N'-dimethytlthiourea and X = Cl- or PF6-, were prepared as suitable precursors for the synthesis of new rhenium complexes potentially useful in nuclear medicine. The infrared (IR) spectra of these complexes were recorded and analyzed and a general vibrational pattern for Re(III) complexes with thiourea derivatives could be established. Approximate assignments for N-allylthiourea and N-ethylthiourea are also proposed for the first time. The synthesis of the new complex [Re(III)(N-allylthiourea)6](PF6)3 is also reported, and information about its structural characteristics was obtained comparing its IR spectrum with those of the other complexes of the investigated series.
Environmental samples from a wide-range of aquatic and soil deposits, mainly of Scandinavian origin, were analysed for 234Th (238U) using low-level gamma-spectrometry. The diversity of the samples, in terms of composition and ages, allowed a detailed evaluation of the analytical problems associated with gamma-ray spectrometry with focus on the reliability of the 234Th peaks for absolute determination of the 234Th activities. The X-ray contributions in the 93 keV peak were compared with the corresponding self-absorption corrected activities of the 63 keV peak. These X-ray contributions were, also, correlated with the 238U, 232Th, 235U, 40K and 137Cs activities of the samples. Despite the difficulties imposed by the self-absorption corrections, the 63 keV peak is still the best option. Large variability in the 93 keV peak interferences, due to X-rays from Th, exists in sediment and soil samples. Only in the case of young ombrotrophic peat samples was it possible to conclude that the 93 keV peak is free from X-ray contributions and can be as good as the 63 keV Monte-Carlo self-absorption corrected peak. X-ray contributions in the samples correlated with the 238U and 232Th activities, only, in closed environmental systems where a secular equilibrium with the daughters of the U/Th series can occur.