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1.
《Journal of Nuclear Science and Technology》2013,50(12):1413-1419
The nuclear fuel reprocessing method FLUOREX is a hybrid system based on fluoride volatility and using solvent extraction. Spent nuclear fuel is fluorinated, and most of the uranium is recovered as UF6 gas. UF6 contains some volatile fission product (FP) fluorides, so we considered their elimination from UF6 by adsorbing them on fluoride adsorbents. We experimentally examined the adsorption of MoF6 on MgF2 adsorbent; MoF6 is present as a volatile FP fluoride in UF6 produced by the fluorination of spent nuclear fuel. The adsorption isotherm of MoF6 adsorption on MgF2 was obtained at MoF6 pressures from 10?4 to 50 kPa. The saturated adsorption amount was 1:3 ± 0:4 mg/m2 at MoF6 pressures from 10?4 to 1 kPa. At MoF6 pressure of about 10?3 kPa, the saturated adsorption amount had no dependence on adsorption temperatures from 398 to 463 K. We deduced that MoF6 was adsorbed as a monomolecule layer on the MgF2 surface at MoF6 pressures from 10?4 to 1 kPa, and the MoF6 partial pressure in UF6 could be decreased below 1 × 10?4 kPa, which is the specific MoF6 concentration for the reenrichment process. 相似文献
2.
《Journal of Nuclear Science and Technology》2013,50(12):1256-1260
Abstract Electron Paramagnetic Resonance (EPR) and optical spectra of uranium(V) species were observed in both processes of photo- and electrolytic reduction of UO2(NO3)2-2tributylphosphate (TBP) in 80%TBP-n-dodecane solution. The formation of U(V) species was detected by an optical spectrum (λmax: 770, 970 and 1,420 nm). EPR signal with the value of ff-factor –2.3 and a linewidth of approximately 1,100 Gs was observed during the electrolytic reduction. On the other hand, during the photoreduction the signal with the value of fil-factor –1.94 was observed and there was found a superhyperfine structure with the intensity ratio of 1:2:1, that is caused by the superhyperfine coupling with nuclear spin, I=1/2, of the strongly coordinated 31P to the central uranium through oxygen atom. The superhyperfine coupling constant was estimated to be 27 Gs. Moreover, the signal with the value of g-factor –2.00 due to an organic radical was observed. The residue after the thermo-gravimetric analysis of UO2(NO3)2-2TBP was identified as α-UP2O7 by the powder X-ray diffraction analysis, indicating the strong coordination of TBP to the central uranium atom. 相似文献