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  • Author or Editor: F. Baumgärtner x
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Abstract  

The fractionation factor of tritium between water and DNA as well as between water and the first hydration shell of DNA is determined. For this purpose the sublimation kinetics of water from DNA dissolved in water were determined at -200 °C and tritium was measured in the remaining water free DNA. The last sublimating water fractions showed a tritium level of about 1.4, the residual water free DNA about 1.9 units above the bulk water. The tritium accumulation inside and near DNA is attributed to the thermodynamic triton-proton exchange isotope effect existing between the strong hydrogen bridges of water and weaker hydrogen bridges as well as inside DNA as between the first hydration shell and DNA.

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Abstract  

Nowadays the PUREX process is the sole accepted reprocessing technique. Its boundary conditions change all the time: former metallic low burnup fuels have been replaced by present ceramic oxide fuels with high burnups, and tomorrow fast breeder fuels with high plutonium contents will have to be processed. In addition, more and more restrictive conditions are being imposed upon waste treatment and more and more stringent safety regulations are being felt. Within these constraints this report presents a survey of the results of recent developments in process technology and gives some reference to the importance of process analytical statements with respect to plant operation. Moreover, recommendations are made for the installation and design of analytical laboratories and some experiences are communicated in the field of process analytical chemistry.

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Abstract  

A compute program MULTINAA was developed to facilitate the evaluation of NAA data. It is written for the VAX/VMS syste and opeates in the Canberra/ND Genie spectroscopy software environment. MULTIINAA can be appliede to relative,k 0-, monostandard (modified) and absolute methods, including the fast neutron threshold reaction. For each calculation, the available standardizations can be used individually or mixed. In all the standardization modes MULTINAA fetches the data directly from the -ray spectra and libraries, thus reducing the manual work to a minimum. MULTINAA is flexibkle to meet various situations in NAA practical work. The required neutron flux parameters all the non-relative methods are supplied by an accompanying program MULTIFLUX.

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Summary  

Tritium exchange and enrichment was studied for several different metal salts, e.g., AlF3 . H2O, FeO(OH), CsI, CsF, NaI, NaF and Al(OH)3 using a cryosublimation apparatus. Experiments were performed below equilibrium vapor pressure to avoid any isotope effects. A comparable tritium enrichment factor of 1.14 to 1.43 was obtained for all systems, except for CsF, which gave an enrichment factor of 1.93. These results confirm the concept, that 3H is accumulated in weak hydrogen bonds as already observed in organic molecules.

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