Radiation Treatment of Exhaust Gases, (XII) NO Removal in Moist NO-SO2-O2-N2 Mixtures Containing NH3

The NO removal by electron beam irradiation was studied in the moist NO-SO₂-O₂-N₂ mixtures containing NH₃. The NO removal was promoted markedly by addition of NH₃ and at the same time, SO₂ was removed. The formations of NO₂, N₂O, NH₄NO₃ and (NH₄)₂SO₄ were observed in the mixtures containing NH₃. The NO removal increased with H₂O and SO₂ concentrations and was hardly affected by the presence of 3–19.5% O₂. The degree of the NO_x(NO+NO₂) removal became larger with decreasing temperature in the range of 80–150°°C. The NO removal was independent of dose rate in the range of 3.1×10⁴–2.4×10⁶ rad/s. The promotion of the NO removal by addition of NH₃ is attributable to the effective decomposition of NO by NH₂ radical formed by the reaction of NH₃ with OH radical. The NO₂ yield decreased by addition of NH₃ and the N₂O yield increased.     

Enrichment of the Uranium Isotopes by Electromigration in a Cation Exchange Membrane

The γ-radiolysis of water subjected to gas bubbling has been studied using a specially desinged gasloop. During the irradiation, N₂ gas was bubbled from the bottom of the irradiation vessel. As the N₂ gas feed rate was raised, the apparent G(H₂) value increased in keeping therewith, from 5 × l0^?3 to 0.26. However in the presence of a sufficient amount of O₂ or H₂O₂, G(H₂) was raised almost to the level of the molecular yield. With reasonable assumptions, it could be concluded that 3～5 × 10^?6 mol/l of H₂O₂ was sufficient to reduce the back reaction of molecular products to less than 10% under the present experimental conditions. It was also found that the G(H₂) value increased with CH₃OH concentration roughly in proportion to log(CH₃OH), and reached 3.1 with 0.1 mol/l CH₃OH.     

Radiation Treatment of Exhaust Gases, (VII)

The NO decomposition by electron beam irradiation was studied in the NO-N₂ and NO-rare gas mixtures. The NO decomposition yields, G (?NO) at low doses in the case of the 500 ppm NO initial concentration were 4.04.4 and 1.2 for the NO-N₂, NO-He and NO-Ar mixtures respectively. A small amount of NO₂ was formed by irradiation of these mixtures. The NO decomposition is mainly attributable to the attacks of N and N₄ ⁺ (or N₂ ⁺), formed by the radiolysis of N₂on NO in the NO-N₂ mixtureand to the attacks of R⁺ and R^*, formed by the radiolysis of a rare gas (R)on NO in the NO-rare gas mixture. The NO decomposition in the NO-N₂ mixture was depressed markedly by the addition of a small amount of O₂. This may be mainly attributable to scavenging of N and N₄ ⁺ (or N₂ ⁺) by O₂.     

Radiation Treatment of Exhaust Gases, (X)

Effects of NH₃, NO, NO₂ and SO₂ on the N₂O formation were studied in the mixtures of H₂O, O₂ and N₂ irradiated with electron beams of 1.5 MeV energy. In the H₂O-O₂-N₂ mixture, the N₂O formation was enhanced markedly by addition of a small amount of NH₃. This enhancement may be brought about by the reaction of NH₃ with OH radical to form NH₂ radical leading to the formation of N₂O. In the NH₃-H₂O-O₂-N₂ mixture, the formation of N₂O was suppressed effectively by addition of NO, NO₂ and SO₂. The N₂O formation was not affected by the irradiation temperature range of 80–200°C.     

Chain Dechlorination of Organic Chlorinated Compounds in Alcohol Solutions by 60Co γ-Rays, (I)

A study was made on radiolytic dechlorination of pentachlorobenzene in alkaline alcohol solutions. The dechlorination yield (G(Cl^?)) was found to depend on the alcohols used as solvent and the concentrations of the chlorinated benzene and hydroxide ion. The high yields obtained in alkaline 2-propanol, sec-butanol and ethanol indicate a chain process in the dechlorination reaction. The value of G(Cl^?) was highest in 2-propanol, and the principal products generated were potassium chloride, acetone and the lower chlorinated benzenes, while a decrease was seen in the hydroxide ion concentration. The concentrations produced of potassium chloride and acetone, as well as the decrease in hydroxide ion concentration, are all roughly equal at all doses. With increasing irradiation dose, pentachlorobenzene was dechlorinated to tetra, tri, di and and monochlorobenzene. 1, 2, 4, 5-tetrachlorobenzene, 1, 2, 4-trichlorobenzene and 1,4-dichlorobenzene were main products. A discussion is given of the detailed mechanism of the dechlorination in alkaline alcohols and the effect of alcohols on G(Cl^?).     

Radiation Treatment of Exhaust Gases, (VIII)

The NO₂ decomposition by electron beam irradiation was studied in the NO₂-N₂ and NO₂-rare gas mixtures. The NO₂ decomposition yields, G (-NO₂), at low doses in the case of the 500 ppm NO₂ initial concentration were 2.9, 10.4 and 5.9 for the NO₂-N₂, NO₂-He and NO₂-Ar mixtures respectively. A large amount of NO was formed by irradiation of these mixtures. The G (NO) was almost equal to the G (-NO₂). The N₂O was also formed in the NO₂-N₂ mixture. The NO₂ decomposition is mainly attributable to the attack of N, formed by the radiolysis of N₂, on NO₂ in the NO₂-N₂ mixture, and to the attacks of R⁺ and R*, formed by the radiolysis of a rare gas (R), on NO₂ in the NO₂-rare gas mixture. The NO₂ decomposition in the NO₂-N₂ mixture was depressed markedly by the addition of a small amount of O₂. This may be mainly attributable to the regeneration of NO₂ by the reaction of NO with O.     

Growth Mechanism of Voids in Fast Reactor Irradiated Austenitic Stainless Steel

The γ-radiolysis of water has been studied using a water-loop specially designed for this purpose. The water was circulated without contact with air during the irradiation. The apparent G(H₂) value was found to be roughly 10-³. However a corresponding amount of O₂ was not found, due to its comsumption by corroding reactions of the constituent materials under radiation field. In the presence of O₂ and H₂O₂, the H₂-yield curves vs. the irradiation dose were revealed a very distinctive characteristic: following a rapid increase with initial irradiation a plateau range has appeared. The H₂-yield at this plateau range depended on the initial concentration of additives. Continued irradiation, however, caused a gradual further rise in the H₂-yield above the plateau value at a rate corresponding to that found in the pure water system. These yield curves are discussed on the basis of the free radical model for the radiolysis of water.     

Development of a New CdTe Area Radiation Monitor using the G(E) Function Method

We developed a small Area Radiation Monitor (ARM) prototype with high accuracy performance by combining a cadmium telluride (CdTe) detector with the G(E) function method. To obtain the measurement accuracy required for ARMs, we created a G(E) function based on detailed spectral responses. The accuracy of the derived dose rate and other expected requirements for practical applications were experimentally evaluated. The accuracy for a CdTe detector with dimensions of 5x5x5 mm³ was within 14% in the 60–300 keV range and within 10% in the 300 keV--1.8 MeV range, which was comparable to a large ARM with an ionization chamber. The accuracy for a CdTe detector with dimensions of 2x2x2mm³ was within 23% in the 60–300 keV range and within 14% in the 300 keV—1.8 MeV range, which was inferior to the 5x5x5 mm³ detector but higher than a small ARM using a silicon PIN photodiode.     

Precipitation of Thorium or Uranium(VI) Complex Ion with Cobalt(III) or Chromium(III) Complex Cation, (II)

The precipitations of thorium and uranium(VI) sulfito complex ions with hexammine cobalt(III) chloride as the precipitant have been studied.

The orange-colored uranium(VI) precipitate obtained is [Co(NH₃)₆]₄[UO₂(SO₃)₃]₃22H₂O, which is in the form of square bipyramid, about 4 μm across in a cubic symmetry of the diamond type with a=10.40Å It decomposes to an oxide mixture of Co₃O₄ and U₃O₈ above 850°C in the air through a sulfate mixture of CoSo₄ and UO₂SO₄.

Composition of the thorium precipitate varies with the precipitation conditions. Therefore, it is considered that the thorium precipitate contains thorium hydroxide and basic thorium sulfite.     

Calculations of Thermodynamic Sulfur Isotope Effect

The isotopic reduced partition function ratios (RPFR), (s/s')f, for the ³⁴S/³²S isotopic pair were calculated for 24 sulfur compounds between 10 and 2,000K. Their magnitudes were in the following sequences; at low enough temperatures at which In(s/s')f depends only on the isotopic difference in frequency-sum, SF₆>SO₂F₂>SF₅Cl>SF₅Br>SO₄ ^2->SO₂Cl₂>SO₃>NSF₃>SF₄>SOF₂>SOCl₂>Me₂SO>SOBr₂>SO₂>SPBr₃>SCBr₂>Me₂S>SPCl₃>SCCl₂>SCF₂>SPF₃>CS₂>OCS>H₂S, and at high enough temperatures at which In(s/s')f is proportional to the isotopic difference in the sum of frequencies squared, SO₂F₂>SO₄ ^2->SO₃>SF₆>SO₂Cl₂>SF₅C1>NSF₃>SF₅Br>SOF₂>SO₂>SF₄>Me₂SO>SCCl₂>SOBr₂>H₂S>Me₂S>CS₂>SCF₂>OCS<SCCl₂>SCBr₂>SPF₃>SPCl₃>SPBr₃ where Me--CH₃. Correlation of the RPFR with molecular structure and molecular forces was discussed.

The equilibrium constants K for the ³⁴S/³²S isotope exchange reactions of all the possible pairs of 19 sulfur compounds selected out of the above 24 were calculated and their temperature dependences were investigated. Two types of temperature dependences were observed; one being smooth monotonic and the other having single cross-over with no pre-inflection.     

Effects of fluid properties on CCFL characteristics at a vertical pipe lower end

The purpose of this study is to derive a counter-current flow limitation (CCFL) correlation and evaluate its uncertainty for steam generator (SG) U-tubes in a pressurized water reactor (PWR). Experiments were conducted to evaluate effects of the liquid viscosity on CCFL characteristics using air–40 wt% or air–60 wt% glycerol water solution and saturated steam–water at atmospheric pressure with vertical pipes simulating the lower part of the SG U-tubes. The steam–water experiments confirmed that CCFL characteristics could be expressed in terms of the Wallis parameters (J_G* and J_L*) for the pipe diameters of D = 14, 20, and 27 mm. A CCFL correlation was derived using the ratio μ_G/μ_L of the viscosities of the gas and liquid phases, μ_G and μ_L, as a correction term representing effects of fluid properties, where J_G^*1/2(μ_G/μ_L)^?0.07 was expressed by a cubic function of J_L^*1/2(μ_G/μ_L)^0.1. In the correlation, the constant C indicating the value of J_G^*1/2(μ_G/μ_L)^?0.07 at J_L* = 0 was (1.04 ± 0.05), and this uncertainty of ±0.05 would cover most of the previous experimental data including the ROSA-IV/LSTF data at 1, 3, and 7 MPa.     

Immobilization of Cs and Sr to HZr2(PO4)3 using an autoclave

The proton-type crystalline zirconium phosphate, HZr₂(PO₄)₃, was prepared by a thermal decomposition of NH₄Zr₂(PO₄)₃ at about 450 °C, where NH₄Zr₂(PO₄)₃ was obtained in advance by a hydrothermal synthesis using a mixed solution of ZrOCl₂, H₃PO₄ and H₂C₂O₄. Cs or Sr ion was immobilized to HZr₂(PO₄)₃ by mixing HZr₂(PO₄)₃ with an aqueous solution of CsNO₃ or Sr(NO₃)₂ under the molar ratio CsNO₃/HZr₂(PO₄)₃ = 1.0 or Sr(NO₃)₂/HZr₂(PO₄)₃ = 0.5. The mixtures were treated thermally in an autoclave at different temperatures from 200 to 275 °C and Arrhenius equation was applied to the Cs and Sr immobilization process to HZr₂(PO₄)₃. The activation energy for the immobilization process of Cs or Sr was estimated as 179 kJ mol^?1 and 186 kJ mol^?1, respectively.     

Selective Uptake of Cesium by Ammonium Molybdophosphate (AMP)-Calcium Alginate Composites

The uptake properties of Cs+ for ammonium molybdophosphate (AMP, (NH₄)₃PMo₁₂O₄₀.3H₂O) and its composite with alginate gel polymer have been studied by the batch and column methods. The free energy for the ion exchange ([NH⁺ ₄]_ad+Cs⁺NH⁺ ₄+[Cs⁺]_ad) was found to have a relatively low value of -9.7 kJ/mol compared to other inorganic ion exchangers, indicating high selectivity of AMP for Cs⁺ ions. The fine crystals of AMP exchanger were granulated with calcium alginate (CaALG) gel polymer as an immobilization matrices. The uptake rate of Cs+ for AMP-CaALG composite was fairly fast and the uptake attained equilibrium within 3 h; the uptake was above 96% even in the presence of 5M (=mol/dm³) NaNO₃. The distribution coefficient of Cs+, Kd-Cs, decreased in the order of coexisting ions, H⁺>Na⁺>K+>NH⁺. In a wide HNO₃ concentration region of 10^-2-5M, the K_d,cs value for the composite was around 10⁴cm³/g, while those for other elements, Na⁺, Sr²⁺, Co²⁺, Eu³⁺ and Am³⁺, were less than 10²cm³/g. The uptake of Cs⁺ followed a Langmuir adsorption isotherm, and the uptake capacity of Cs⁺ increased with the content of AMP immobilized in the composite. The trace amounts of Cs⁺ in the presence of HNO3 were selectively adsorbed on the composite column.     

Chain Dechlorination of Organic Chlorinated Compounds in Alcohol Solutions by 60Co γ-Rays, (III)

Chlorinated benzenes dissolved in deoxygenated alkaline 2-propanol were dechlorinated by irradiating with ⁶⁰Co γ-rays to produce the lower chlorinated benzenes and chloride ion. The yield of dechlorination was found to depend on the number of chlorine atoms on the benzene ring, the G (CI^?)-values being, for instance, 6,500, 480 and 2.0 for 0.07 M penta-chlorobenzene, 1, 2, 4-trichlorobenzene, and monochlorobenzene, respectively, in 0.2 M KOH-2-propanol solution. In contrast, the values of G(C1^?) differed little between the isomers of trichlorobenzene. The large difference in G (CI^?) according to the number of chlorine atoms can be explained by considering the redox potential of the chlorinated benzenes and the ketyl radical ion.

Trichlorobenzene is dechlorinated to dichlorobenzene and then to monochlorobenzene while producing potassium chloride and acetone, and consuming hydroxide ion. In the experiment, some chlorinated benzene derivatives were observed to be generated in the course of this process—probably dichlorophenyl-2-propanol and monochlorophenyl-2-propanol, judging from observation by gaschromatograph-mass spectrometer and from the path-way of formation. The observation also indicated the presence of dichlorophenyl-2-propanol in predominant amounts in 1, 3, 5-trichlorobenzene solution, but only in a small fraction in 1, 2, 3-trichlorobenzene.     

Radiation Damage of Organic Extractant in Partitioning of High-Level Liquid Waste, (I)

Di(2-ethylhexyl)phosphoric acid (DEHPA), which is a useful extractant for the treatment of high-level liquid waste, was exposed to ⁶⁰Co γ-rays and the radiolysis products and their yields were determined.

The major radiolytic decomposition process of DEHPA was found to be a stepwise splitting of two alkyl groups resulting in MEHPA and H₃PO₄. 1-Methyl-1-ethylpentyl radical, C₄H₉-C(CH₃)-C₂H₅, was found to form with a large G value in the γ-irradiated DEHPA. Reactions involving 1-methyl-1-ethylpentyl radical were also discussed.     

Radiation Treatment of Exhaust Gases, (XIV)

The computer simulation method has been applied to the analysis of the NO oxidation and decomposition in the dry and moist NO-O²-N²mixtures by electron beam irradiation. The calculated results were in good agreement with the experimental results for both mixtures. The NO in the dry NO-O²-N² mixture is decomposed by the reaction with N(⁴S) formed by the radiolysis of the O²N²mixture and is oxidized by the reactions with O and with O³ formed through the reaction of O² with O. The NO in the moist NO-O²-N²mixture is oxidized not only by the reaction with OH formed by the radiolysis, but also by the reaction with O³ formed through the reaction of O² with O at low dose. The G values of the formations of the active species obtained by the computer simulation were G(N(⁴S)) =1.1, G(N(²D))=0.9 and G(O)=1.7 for the dry NO-O²-N² mixture and G(O)=2.0 and G(HO²)= 0.17 for the moist NO-O²-N² mixture. Also, the analysis by the computer simulation confirmed the value of G (OH)=3.2 obtained in the moist O²-N² mixture by the competition method.     

Elution Behavior of Cesium from Ferrierite Column by Using Inorganic Salt and Acid Solutions

The distribution coefficient (K_d) of Cs on ferrierite decreased with increasing concentration of the coexisting inorganic cations in the order of Na⁺>H⁺>K⁺>NH₄ ⁺. A linear relationship with a slope of about —1 was obtained between log K _d and log[M⁺] above 0.1M (=mol/dm³). The retention volume (V _R ) of Cs in chromatography also decreased in a similar manner to K _d , depending on the kind of inorganic cations. The V _R value can be predicted from the K _d value based on the linear relation. The column efficiency was improved with fine particles of ferrierite, yielding the elution percentage above 95%.     

Alkali Metal Ion and Lithium Isotope Selectivity of HZr2(PO4)3

HZr₂(PO₄)₃ has been synthesized by the heat treatment of NH₄Zr₂(PO₄)₃ and its properties as an ion exchanger have been examined with the main focus on its alkali metal ion and lithium isotope selectivity. The distribution coefficients for alkali metal ions revealed that HZr₂(PO₄)₃ was lithium ion-specific and showed little affinity toward potassium, rubidium or cesium ion. The lithium and sodium ion uptakes from aqueous solutions were monotonously increasing functions of pH. Isotopically, HZr₂(PO₄)₃ was ⁶Li-specific. Contrary to ion uptake, the lithium isotope effect was a monotonously decreasing function of pH; a larger separation factor was observed at a lower pH. This result was consistent with the existence of two different ion exchange sites formed in lithium ion-inserted HZr₂(PO₄)₃.     

Determination of the composition and instability constants of complex Pu+3oxalate ions

The solubility of Pu₂(C₂O₄)₃ · 9H₂O in aqueous solutions of K₂C₂O₄ of various concentrations (0.01–2.4 moles /liter) has been determined at constant ionic strength of the solution at 20. It was found that Pu⁺³ complexes are formed in these solutions. It was found from the results of Pu₂(C₂O₄)₃ · 9H₂O solubility determinations that in the region of K₂C₂O₄ concentrations studied the following complex ions are formed [Pu(C₂O₄)₂]^?, [Pu (C₂O₄)₃]^?3 and [Pu (C₂O₄)₄]^?5, the total instability constants of which are 4.9 · 10^?10; 4.10 · 10^?10 and 11.9 · 10^?11 respectively. The solubility of Pu₂(C₂O₄)₃ · 9H₂O in aqueous (NH₄)₂C₂O₄ solutions has also been determined in the range of ammonium oxalate concentrations from 0.07 to 0.7 mole/liter at 70 °. It is shown that the composition of the complex ions under these conditions corresponds to [Pu(C₂O₄)₂]^?, [Pu(C₂O₄)₃]^?3 and [Pu(C₂O₄)₄]^?5. The calculated total instability constants of these complex ions are 11.6 · 10^?9; 5.6 · 10^?9 and 2.5 · 10^?9 respectively. The heats of formation of complex Pu⁺³ oxalate ions have been calculated for the reaction Pu⁺³ + nC₂O₄ ^?2 ?[Pu(C₂O₄)_n]^3?2n Δ¯Q for the [Pu(C₂O₄)₂]^? ion is 1300 cal., for [Pu(C₂O₄)₃]^?3, 1200 cal., and for [Pu(C₂O₄)₄]^?5, 1300 cal.     

Solubility of Uranyl Nitrate Precipitates with N-Alkyl-2-pyrrolidone Derivatives (Alkyl = n-Propyl,n-Butyl,iso-Butyl,and Cyclohexyl)

The solubility of UO₂(NO₃)₂(NRP)₂ (NRP = N-alkyl-2-pyrrolidone) in aqueous solutions with HNO₃ (0–5.0 M) and the corresponding NRP (0–0.50M) has been studied. As a result, the solubility of each speciesof UO₂(NO₃)₂(NRP)₂ generally decreases with increasing concentrations of HNO₃ and the corresponding NRP (C _HNO3 and C _NRP, respectively) in the supernatant. The solubility of UO₂(NO₃)₂(NRP)₂ also depends on the type of NRP; a higher hydrophobicity of NRP generally leads to a lower solubility of UO₂(NO₃)₂(NRP)₂. The logarithms of effective solubility products (K _eff) of UO₂(NO₃)₂(NProP)₂, UO₂(NO₃)₂(NBP)₂, UO₂(NO₃)₂(NiBP)₂, and UO₂(NO₃)₂(NCP)₂ at different C_HNO3 values and 293K were evaluated. For instance, at C_HNO3 = 3:0 M, logK ^NProP _eff = ?1:07 ± 0:03, log K ^NBP _eff = ?2:23 ± 0:02, log K ^NiBP _eff = ?2:59 ± 0:03, and log K ^NCP _eff = ?3:80 ± 0:05. The solubility of UO₂(NO₃)₂(NRP)₂ is determined by the balance among the common-ligand effect, ionic strength, and variation of log K _eff with C _HNO3.