Yusuke Kuno

Solubility of Tributylphosphate in Plutonium Nitrate Solution and Highly Radioactive Liquid Waste Solution

Abstract The solubility of tri-n-butylphosphate (TBP) in aqueous solutions of plutonium nitrate (PuN) and in highly radioactive liquid waste (HRLW) of PUREX nuclear fuel reprocessing was investigated. By an empirical formula the solubility of TBP in PuN solutions was described in the range of 0–0. 1 M Pu and 1–8M HNO3 concentrations. The following items were elucidated: (1) The logarithm of TBP solubility (S) in the solution of interest varies inversely in proportion to the concentration of Pu(IV) in the range of 0–0.1M PU(IV) at a constant concentration of HNO3, indicating that Pu(IV) simply behaves as an electrolyte for the salting-out of TBP. Log S subsequently levels off with increasing Pu concentration, which would be due to a change in the principal dissolution form of TBP having an interaction with Pu (IV). (2) The variation in S in PuN solutions (0–0.1M PU) with nitric acid concentration shows almost the same tendency as that in HNO3 solution. (3) A dependency of S on fission product metal ions in...

Radiolytically Generated Hydrogen and Oxygen from Plutonium Nitrate Solutions.

Abstract Hydrogen and oxygen gases radiolyticaily generated in a nitrate system by α-radiation were investigated. The following points were elucidated: (1) Plutonium (IV) is involved in the G-value for hydrogen generation. The difference in G-values in 244Cm-HNO3 solution and Pu(IV)-HNO3, solution can be explained by the presence of Pu. (2) No significant effect of the difference of oxidation states. Pu(IV)/Pu(VI), resulting from heating solution on the hydrogen generation was observed. (3) Radiolytic evolution of hydrogen in plutonium nitrate solutions depends upon a height of the solution in a vessel, although this dependence is apparently less than that observed under γ-radiation. (4) The effect of the solution height would be explained by a reaction between OH and H2 because the effect can be approximately described by concentrations of undissociated HNO3 and Pu(IV), which are thought to be primary scavengers of OH radicals. (5) The G-value for oxygen generation in plutonium nitrate solutions was roug...

Degradation of Tributylphosphate in Plutonium Nitrate Solution

Degradation of tri-n-butylphosphate (TBP) dissolved in aqueous nitrate systems containing Pu was investigated under various conditions. The difference of degradation rates of TBP observed in reprocessed Pu streams and in nitric acid is discussed. The followings were elucidated: (1) The degradation of TBP in plutonium nitrate solutions depends upon the Pu concentration although it indicates first-order kinetics. (2) The half life of TBP increases linearly with HNO3 concentration in plutonium nitrate solutions. The retardation by undissociated HNO3 is almost independent of Pu concentration. (3) No significant effect of HNO2, generated by radiolysis, on the TBP degradation rate was observed. (4) The retardation of the degration of TBP can be described only with the concentrations of Pu and HNO3. (5) The G-values of TBP in plutonium nitrate solutions extremely decrease with increasing the concentrations of HNO3 and Pu. (6) Plutonium other than undissociated HNO3 would be involved in the retardation due to OH ...

On-line determination of iodine in nuclear fuel reprocessing off-gas streams by a combination of laser-induced fluorimetry and laser photoacoustic spectroscopy

Abstract The on-line determination of molecular iodine and orgabic iodides in nuclear fuel reprocessing off-gas streams containing high concentration of NO itx gas was studied. Ultraviolet radiation is used to convert organic iodides into molecular iodine. The approximate concentration of iodine before and after the photochemical conversion in the presence of NO itx gas was first determined by laser-induced fluorimetry. NO 2 was determined by photoacoustic spectroscopy, correcting the acoustic signal due to iodine by using the approximate iodine concentrion. NO was determined from the concentrations of NO 2 before and after the photoirradiation based on the photochemical fraction changes of NO and NO 2 . The quenching of the fluorimetry due to NO and NO 2 was finally corrected with the NO and NO 2 concentrations obtained. The detection limit of the proposed method is 10 nl 1 -1 .