Losses radionuclides

Investigate accidents which may have led to persons receiving effective doses in excess of 6 mSv or an equivalent dose greater than 30% of any relevant dose limit. Investigate and report to the authorities loss of materials from accidental release to atmosphere, spillages, theft. The Regulations provide a comprehensive list of notifiable concentrations for each radionuclide isotope. 

Figure 2. (A.) The radionuclides in an aquifer are divided into three reservoirs groundwater, the host aquifer minerals, and adsorbed onto active surfaces. Also shown are the processes adding to a daughter nuclide (closed circles) in the groundwater of weathering, advection, recoil from decay of parent atoms ( P ) in the aquifer minerals, and production by parent decay, the processes of losses of a radionuclide of advection and decay, and exchange between dissolved and adsorbed atoms.

Since Ra and " Ra are both produced by recoil from the host mineral, it might be assumed that the production rates are equal. However, the relative recoil rates can be adjusted by considering that the parent nuclides near the mineral surface may not be in secular equilibrium due to ejection losses i.e., the activity of Th may be lower than that of Th due to recoil into groundwater of the intermediate nuclide Ra. Krisnaswami et al. (1982) calculated that the recoil rate of " Ra is 70% that of Ra if radionuclides are depleted along the decay chain in this way. 

The most susceptible material for post-depositional loss or addition of radionuclides is the outer layer of samples that have been exposed to moisture for a long duration. Stratigraphic consistency between ages of the outermost material and that deposited prior to this provides valuable constraints on the technique. Four ages were derived for a band of clear, white calcite deposited on a stalactite from 53.6 m below sea level in a blue hole of Andros, Bahamas (Richards et al. 1994). Isotopic data for the outermost surface, which had been exposed to sea water for at least 8 ka was indistinguishable from the internal material (Fig. 8). 

It has been demonstrated that monoclonal antibodies may be chemically modified by reaction with metal chelates without loss of antibody activity or specificity. A radionuclide generator has been made to provide a source for Bi-212 to be used for attachment of bismuth chelates to antibody. Such antibody-metal-chelate conjugates appear to be stable in vivo and may provide a new method for radiotherapy. 

The collection and preparation of water samples requires individual approaches for different analytical tasks. If heavy metals or long-lived radionuclides at the trace and ultratrace concentration range are to be determined in water samples by ICP-MS, especially careful sampling is necessary to avoid possible contamination (using clean bottles and containers washed and cleaned before use, for example, with 2 % nitric acid and high purity water to stabilize traces in the samples), and the loss of analyte by adsorption effects or precipitation should be also considered. 

The use of anticoincidence shielding significantly reduces the Compton continuum and allows the detection of weak spectral lines usually masked by interfering Compton radiation. Further improvement resulted from separate recording of the coincidence and anticoincidence thus, radionuclides that normally decay with a coincidence scheme can be recorded without loss of efficiency. 

The high energy primary cosmic rays produce many secondary neutrons and protons which in turn are responsible for most of the spallation reactions resulting in radionuclide production in the atmosphere. The formation of these radionuclides occurs at reaction thresholds of 10-40 M.e.v. Because of local ionization losses the secondary protons lose their... 

Because small amounts of radium radionuclides in environmental samples may be regarded as hazardous, it is usually necessary to detect very small quantities of radium which may require processing large quantities of sample (Quinby-Hunt et al. 1986). This introduces possibilities for contamination and sample loss. Specifically, in the case of water samples, sorption of the radionuclide to container walls and to suspended matter may be important sources of error. 

IJA is the rate of decomposition of detritus in environment A kA is the kinematical coefficient of vertical diffusion is the velocity of nutrient assimilation by the photosynthetic process per unit of phytoplankton production ef is the proportional part of the eth radionuclide that is chemically analogous to B6 A on substrate A H is the rate of input flow of the eth radionuclide 7) is the rate of exchange with the environment p is that part of biomass losses due to exchange that transforms into nutrients (Legendre and Legendre, 1998) and f3v is upwelling velocity. Equation (6.1) is the basic element of block NM. 

Chadwick, R.C. Chamberlain, A.C. (1970) Field loss of radionuclides from grass. Atmospheric Environment, 4, 51-6. 

Fig. 7-2. Summary of environmental pathways by which terrestrial plants may become contaminated with radionuclides. In the case of an input from atmosphere, or as a result of the process of resuspension , any external radionuclide burden may be reduced by field loss mechanisms conversely, an initially external radionuclide deposit (Rat) may become internalised (i int) following foliar absorption and translocation. Radioactive contaminants of soils may be derived either from atmospheric inputs or from seepage in ground waters. Partitioning of radionuclides in soil—soil water systems controls their availability for root absorption, which normally occurs exclusively from the liquid phase. The chemical speciation of the nuclide in this phase, however, provides a further control on bioavailability which is highly radionuclide specific.

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