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Abstract  

In order to measure 182Hf by accelerator mass spectrometry (AMS), a chemical procedure for separation of hafnium from tungsten has been developed by extraction chromatography. The extraction chromatographic behavior of hafnium and tungsten has been studied using tri-n-octylamine (TOA) as the stationary phase, HCl–H2O2 mixture and NH3·H2O as the mobile phase. The effects of H2O2 concentration, column loading and column dimensions are investigated. Hf and W with microgram amounts are successfully separated on a chromatographic column (Ø5 × 196 mm), on which Hf is hardly retained after completely eluted with 6 M HCl–1% H2O2 and W strongly adsorbed is then eluted with 3 M NH3·H2O. The decontamination factor for tungsten is 3.0 × 105 and the recovery of hafnium is better than 99% using a single column separation.

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Abstract  

The sorption of Eu(III) on calcareous soil as a function of pH, humic acid (HA), temperature and foreign ions was investigated under ambient conditions. Eu(III) sorption on soil was strongly pH dependent in the observed pH range. The effect of ionic strength was significant at pH < 7, and not obvious at pH > 8. The type of salt cation used had no visible influence on Eu(III) uptake on soil, however at low pH values, the influence of anions was following the order: Cl ≈ NO3  > ClO4 . In the presence of HA, the sorption edge obviously shifted about two pH units to the lower pH, whilst in range of pH 6–7, the sorption of Eu(III) decreased with increasing pH because a considerable amount of Eu(III) was present as humate complexes in aqueous phase, then increased again at pH > 11. The results indicated that the sorption of Eu(III) on soil mainly formed outer-sphere complexes and/or ion exchange below pH ~7; whereas inner-sphere complexes and precipitation of Eu(OH)3(s) may play main role above pH ~8.

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Abstract  

The recombination of hydrogen and oxygen in technical gaseous waste of nuclear power plants in enlarged scale experiment has been studied on the basis of our previous work.1 The catalyst and its best operating conditions for recombination of hydrogen and oxygen determined in a small scale experiment were demonstrated and tested. The results show that the data obtained in an enlarged scale experiment agreed well with that of in a small scale test. The recombination rate of H2 and O2 was higher than 98.3% and 99.98% respectively. After recombination, the residual concentrations of H2 and O2 in waste gas were O2<3 ppm, H2<400 ppm. The Pd-Al2O3 catalyst and operating conditions determined for gaseous waste processing of nuclear power plants were satisfactory.

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Abstract  

The recombination of hydrogen and oxygen in technical gaseous waste of nuclear power plants has been studied. A highly efficient catalyst for reacting H2 with O2 to form water was prepared. Various operating conditions and factors affecting the recombination of H2 and O2 were tested and the best conditions were determined. Results show that the Pd–Al2O3 catalyst prepared had very good characteristics. The recombination rate of H2 and O2 was higher than 98.3% and 99.9%, respectively. After recombination, residual concentrations of H2 and O2 in waste gas were O2<3 ppm, H2<400 ppm. The Pd–Al2O3 catalyst and operating conditions determined for gaseous waste processing of nuclear power plants were satisfactory.

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