H. Diamond

Separation and preconcentration of actinides by extraction chromatography using a supported liquid anion exchanger : application to the characterization of high-level nuclear waste solutions

A novel extraction chromatographic resin comprised of a quaternary amine-based liquid anion exchanger sorbed on an inert polymeric substrate for the sorption of actinides from nitric and hydrochloric acids is described. The resin is shown to exhibit preferential retention of tetravalent actinides over a wide range of acidities. The application of this material to the separation and preconcentration of selected actinides from high level nuclear waste solutions for subsequent determination is described.

EXTRACTION OF Am FROM NITRIC ACID BY CARBAMOYL-PHOSPHORYL EXTRACTANTS: THE INFLUENCE OF SUBSTITUENTS ON THE SELECTIVITY OF Am OVER Fe AND SELECTED FISSION PRODUCTS

A number of neutral extractants containing the P(0)(CH2)nC(0)N raolety were evaluated for their ability to extract Am from nitric acid and their selectivity for Am over Fe and selected fission products. Extractants containing alkoxy, alkyl, and aryl substltuents were evaluated. Tetrachloroethylene was used as a diluent. Fission products selected for study were Y, Zr, Mo, Tc, Ru, Rh, Pd, La, Ce, Pr, Nd, Sra, and Eu. The conclusions drawn were that the most efficient and selective Am extractant contains a single carbon bridging group, one or two phenyl groups attached to the phosphorus atom and l9obutyl groups attached to the amide nitrogen.

Selected Alkyl(phenyl)-N,N-dialkylcarbamoylmethylphosphine Oxides as Extractants for Am(III) from Nitric Acid Media

Abstract A new series of neutral bifunctional extractants, alkyl(phenyl)-N,N-dialkylcarbamoylmethylphosphine oxides, has been prepared and studied as extractants for Am(III) from nitric acid media. Two types of alkyl(phenyl)-N,N-dialkyl CMPO compounds were prepared, one containing N,N-diethyl groups and the other containing N,N-diisobutyl groups. The N,N-diethyl series contained hexyl(phenyl) and 6-methylheptyl(phenyl) derivatives, abbreviated HφDECMPO, and 6-MHφDECMPO, respectively. The N,N-diisobutyl series contained the n-octyl(phenyl), 6-methylheptyl(phenyl), and the 2-ethylhexyl(phenyl) derivatives, abbreviated OφD[IB]CMPO, 6-MHφD[IB]CMPO, and 2-EHφD[IB]CMPO, respectively. Third power extractant dependencies for the extraction of Am(III) from 0.5 and 3 M HNO3 were obtained at low (<0.25 M) concentrations of extractant, but higher power dependencies were obtained above 0.25 M extractant from 3 M HNO3. The HφDECMPO, 6-MHφDECMPO, 6-MHφD[IB]CMPO, and OφD[IB]CMPO [all 0.5 M in diethylbenzene (DEB)] are si...

UPTAKE OF METAL IONS BY A NEW CHELATING ION-EXCHANGE RESIN. PART 1: ACID DEPENDENCIES OF ACTINIDE IONS*

ABSTRACT The uptake of several actinide ions [U(VI), Pu(IV), Np(IV), Th(IV] and Am(DI)) from nitric and hydrochloric acid solutions, and of U(VI) from near-neutral solutions by the new chelating ion-exchange resin, DiphonixTM, has been investigated. Diphonix is a polyfunctional resin containing sulfonic and gem-diphosphonic acid groups chemically bonded in a styrene-divinylbenzene polymeric network. Comparison of the acid dependencies of the actinide ions uptake measured with Diphonix with those obtained using a commercial sulfonic -type resin and a resin containing both sulfonic and monophosphonic aCid groups, hat Shown that Diphonix binds the actinides via a different kind of chemical interaction, involving the.formation of chelate complexes through the phosphoryl groups of the gem-diphosphonic acids. As a consequence, Diphonix is superior to other resins in extracting actinide ions from very acidic solutions. A better performance of Diphonix is also observed with the uptake of uranium from neutral solu...

SELECTIVITY-STRUCTURE TRENDS IN THE EXTRACTION OF Co(II) AND Ni(II) BY DIALKYL PHOSPHORIC, ALKYL ALKYLPHOSPHONIC,AND DIALKYLPHOSPHINIC ACIDS∗

Abstract The conditional equilibrium constants for the extraction reactions of Co(II) and Ni(ll) by toluene solutions of homologous series dialkyl phosphoric, alkyl alkylphosphonlc, and dialkyl-phosphlnic acids have been evaluated. From the equilibrium constants the Co/Ni selectivity factors were calculated. Absorption spectra and water extraction data for organic solutions of selected reagents which had extracted the metals were also obtained. The data have allowed us to establish correlations between the structure of the extractants and their selectivity for Co(II) over Ni(II). The two main features controlling the different extractive behavior of Co(II) and Nl(II) with the organo-phosphorus reagents appear to be the different degree of hydration of the extracted complexes and their different coordination geometry. Sterlc hindrance effects, introduced by branchings on the alkyl chains greatly reduce the extractability of Ni(II) which forms octahedral complexes in the organic phase, while the extraction ...

Nuclear constants of nine transplutonium nuclides

Abstract The total half-lives of 252Cf, 250Cf, 253Cf are 2·646 ± 0·004 years, 13·2 ± 0·5 years and 17·6 ± 0·2 days. The ratios of α-emission to spontaneous fission for 252Cf, 250Cf, 253Es and 244Cm are 31·3 ± 0·2, 1260 ± 40, (1·15 ± 0·03)107 and (7·43 ± 0·01)105. The partial spontaneous fission half-life of 246Cm = (1·66 ± 0·10)107 years. The thermal neutron fission cross sections for 249Cf and 251Cf are 1735 ± 70 barns and 3000 ± 260 barns. A separate determination and a re-evaluation of the data from the MIKE thermonuclear event confirms the 60·5 ± 0· 2 day 254Cf half-life reported by others.

THE EXTRACTION OF SELECTED ACTINIDES IN THE ( III) (IV) AND ( VI) OXIDATION STATES FROM HYDROCHLORIC ACID BY Oπ D( iB) CMPO: THE TRUEX-CHLORIDE PROCESS∗

ABSTRACT The extraction of tetravalent Th, Np, and Pu and hexavalent U from hydrochloric acid was studied using octyl(phenyl)-N,N-diiso-butylcarbamoylmethylphosphine oxides, 0π D(iB)CMP0 or CMPO, dissolved in tetrachloroethylene (TCE). A 0·5 MCMPO solution in TCE was found to be an extremely effective extractant for the tetravalent actinides and U(VI) from moderate to concentrated HC1. Extractant dependencies of the distribution ratios of Th(IV), U(VI), and Pu(IV) were 3rd, 2nd, and 3rd power, respectively, indicating the following species: ThCl4’3CMPO, UO2Cl22CMP0, and PuCl4»3CMPO. The distribution ratios of a variety of non-actinide elements, including selected alkali, alkaline earths, Al, transition and post-transition metal ions were also measured from 2 Mand 6 M_ HC1. Based on the distribution ratios of tri-, tetra-, and hexavalent actinides from chloride media, a generic actinide extraction/recovery process was developed for the removal of actinides from chloride salt wastes. The process is called T...

EXTRACTION OF AMERICIUM(III) FROM CHLORIDE MEDIA BY OCTYL(PHENYL)-N,N-DIISOBUTYLCARBAMOYLMETHYLPHOSPHINE OXIDE∗

ABSTRACT The extraction of Am(III) from chloride media was studied using octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide, Oπ D(iB)CMPO or CMPO, dissolved in tetrachloroethylene. Although the extraction of Am(III) by 0πD(iB)CMPO is many orders of magnitude weaker from chloride than nitrate media, the rapid Increase in the mean activity of chloride in HC1 and in most soluble chloride salts with concentration makes extraction from moderate to concentrated hydrochloric acid and/or concentrated Li, Mg, Ca, and Al chloride salt solutions practical. The stoichiometry of the extractable chloro complex was established by extractant dependency and loading experiments and found to be AmCl3»3CMPO. Hydrochloric acid appears to be associated with the complex when extraction takes place at high HC1 concentrations. The mode of coordination of OπD(iB)CMPO to AmCl3appears to be bidentate in marked constrast to its behavior in the corresponding nitrate system.

The half-lives of 245Cm, 246Cm, 248Cm, 250Cf, 251Cf and 249Cf☆

Abstract The partial α-half-lives of 245 Cm, 246 Cm, 248 Cm, 250 Cf, 251 Cf and 249 Cf have been determined to be 8265 ± 180 yr, 4711 ± 22 yr, (3·84 ± 0·04) 10 5 yr, 13·08 ± 0·09 yr, 900 ± 50 yr, and 352 ± 6 yr respectively. Partial spontaneous fission half-lives of (1·80 ± 0·01) 10 7 yr and (4·22 ± 0·12) 10 6 yr were determined for 246 Cm and 248 Cm, respectively.

THE INFLUENCE OP THE DILUENT ON THE DISTRIBUTION BEHAVIOR OF OCTYL(PHENYL)-N,N-DIISOBUTYLCARBAMOYLMETHYLPH0SPHINE OXIDE*

ABSTRACT The degree of Interaction or compatibility of the neutral bifunctional extractant 0фD(lB)CMP0 with a diluent was determined by measuring the distribution ratio of the extractant between two phases. The distribution ratio, DCMPO, was highest in chloro-carbon and aromatic diluents with small molar volumes and lowest in normal paraffinic hydrocarbon diluents with large molar volumes. An approximate correlation between DCMPO in a variety of diluents and the solubility parameter (𝛅) of the diluent was obtained using equations for regular solutions and b.delta;H2o =34.8. A much better correlation was obtained between DCMP0 find an empirical solution parameter. It was found that the distribution ratio of diisobutylcarbamoylmethylphosphine oxides increased by 3 orders of magnitude as the basicity of the phosphoryl group on the extractant was increased by the replacement of two phenyl substi-tutents on the phosphorus atom with two octyl groups The influence of TBP as a phase modifier in 0фD (iB)CMPO -dilu...