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The solubility of zirconium(IV) hydrous oxide was measured in the hydrogen ion concentration (pH

The multiplicity and energy of the prompt neutrons emitted from the fission fragments for 239 Pu(nth, f) were measured as functions of the fragment mass and total kinetic energy. The results were compared with those for 233 U(nth, f) and with the predicted values by the multi-channel fission theory with the random neck rupture model.The measured and predicted values of the neutron multiplicity, (v)(m*), show the saw-tooth trend and agree with each other. The total neutron multiplicity decreases linearly with increasing total kinetic energy resulting in -d(TKE)/d(vt 0 t)=16.5±0.4MeV/neutron. The slope of the neutron multiplicity vs. the total kinetic energy, -d(v) / d(T KE), was plotted against the fragment mass. Its shape agrees with that for 233 U(nth, f).The average neutron emission energy, (rJ)(m*), follows a bell shape about the symmetric fission accompanying higher values for very asymmetric fissions and agrees with that for 233 U(nth, f). The total excitation energy (TXE)(m*) was determined by two manners: (1) neutron data and (2) Qmax-(TKE). Both results satisfactorily agree with each other as the case of 233 U(nth, f), and thereby the present derivation of (TKE) from the neutron data is confirned.

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The solubility of zirconium(IV) hydroxide and oxide was measured in the acidic, neutral and alkaline pH at 25 C by an undersaturation method. No influence of the formation of polynuclear and colloidal species on the apparent solubility was observed in the case of the ZrO 2. By using the solubility data of the ZrO 2 and by considering the contributions of the mononuclear species, Zr 4þ , ZrOH 3þ and Zr(OH) 4 (aq), to the solubility curve in the lower pH region, the solubility product was obtained to be log K sp ¼ À62:46 AE 0:10. In the case of the Zr(OH) 4 , no equilibrium was observed during the experimental period up to four months.

The solubility of U(VI) was measured in highly basic solutions (pOHc = -logfOH"] ranges from 3 down to 0) at the ionic strength I = 0.5-2.0 Μ (Μ: mol dm -3 ) over a wide range of carbonate ion concentrations C = IX 10~3-0.5 Μ by both oversaturation and undersaturation methods. In oversaturation experiments, the solubility of U(VI) decreased with increasing equilibration time from 1 week to 1 year, suggesting an increase in the crystallinity of the solid phase with aging. The solid phase was identified as Na 2 U 2 0 7 · χ H 2 0 (x = 3-5) by X-ray diffraction. Undersaturation experiments conducted for 1 month with this solid phase indicated a rapid attainment of equilibrium. These data were well interpreted by considering the formation of [U0 2 (0H) 3 ]", [U0 2 (0H) 4 ] 2 " and [U0 2 (C0 3 ) 3 ] 4 ", and the apparent equilibrium constants for [UO 2 (0H) 3 ]~ and [U0 2 (0H) 4 ] 2 " were determined with fairly small deviations. Using the evaluated solubility product of Na 2 U 2 0 7 · χ H 2 0 (χ = 3-5), the stability constants for the above species were evaluated. The upper limit values of the stability constants of the carbonatohydroxodioxouranium(VI) complexes were also evaluated.

In a study of the adsorption behavior of cations onto quartz, the distribution coefficient of a variety of cations was determined using the batch method, and using the titration method, the surface charge densities of quartz in a number of electrolyte solutions. The two values thus determined were analyzed applying the electrical double-layer model, from which optimum parameter values were derived for double-layer electrostatics and intrinsic adsorption equilibrium constants. Based on these parameter values, the mechanism of cation adsorption is discussed: A key factor governing this mechanism proved to be the hydration behavior of cations. Consideration of the Coulomb interaction between the adsorbate ions and adsorbent surface led to the finding of a simple rule governing in common the adsorption equilibrium constants of different metal ions.