Gordon D. Jarvinen

The Attractiveness of Materials in Advanced Nuclear Fuel Cycles for Various Proliferation and Theft Scenarios

We must anticipate that the day is approaching when details of nuclear weapons design and fabrication will become common knowledge. On that day we must be particularly certain that all special nuclear materials (SNM) are adequately accounted for and protected and that we have a clear understanding of the utility of nuclear materials to potential adversaries. To this end, this paper examines the attractiveness of materials mixtures containing SNM and alternate nuclear materials associated with the plutonium-uranium reduction extraction (Purex), uranium extraction (UREX), coextraction (COEX), thorium extraction (THOREX), and PYROX (an electrochemical refining method) reprocessing schemes. This paper provides a set of figures of merit for evaluating material attractiveness that covers a broad range of proliferant state and subnational group capabilities. The primary conclusion of this paper is that all fissile material must be rigorously safeguarded to detect diversion by a state and must be provided the highest levels of physical protection to prevent theft by subnational groups; no “silver bullet” fuel cycle has been found that will permit the relaxation of current international safeguards or national physical security protection levels. The work reported herein has been performed at the request of the U.S. Department of Energy (DOE) and is based on the calculation of “attractiveness levels” that are expressed in terms consistent with, but normally reserved for, the nuclear materials in DOE nuclear facilities. The methodology and findings are presented. Additionally, how these attractiveness levels relate to proliferation resistance and physical security is discussed.

Open-celled polymeric foam monoliths for heavy metal separations study

Open-celled polymeric foam monoliths prepared by high internal phase emulsion polymerization (HIPE) are being investigated as improved materials for separation of heavy metals. In column flow studies, the foam monoliths have high flow rates and are durable up to at least 40 psi. A 4-vinylpyridine functionality has been incorporated into vinylbenzylchloride/styrene copolymer foams by graft-polymerization of vinylpyridine. The open structure of the foam and the flexible graft-polymerized ion-exchange chains result in improved kinetics in metal uptake. Iron uptake kinetics were greatly increased in the grafted foams over resin beads of similar structure. Plutonium uptake kinetics were moderately increased in the foams.

THE USE OF SOFT DONOR LIGANDS, 4-BENZOYL-2,4-DIHYDRO-5- METHYL-2-PHENYL-3H-PYRAZOL-3-THIONE AND 4,7-DIPHENYL-UO- PHENANTHROLINE, FOR IMPROVED SEPARATION OF TRIVALENT AMERICIUM AND EUROPIUM

ABSTRACT The extraction of Am(ITI) and Eu(III) from aqueous 0.1 M NaClO4 using a mixture of 4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione (HBMPPT) and 4,7-diphenyl-l,10-phenanthroline (DPPHEN) was studied. Individually, neither the HBMPPT nor the DPPHEN in toluene showed any extraction capabilities for Am(III) or Eu(III) under the experimental conditions used in this study. Combination of the two ligands, however, yielded a synergistic system which showed a strong preference for Am(III) over Eu(III). Slope analysis indicated that the extracted species took the form M(BMPPT)3(DPPHEN) for both metal ions studied. The separation factor DAm/DEu was 190 at pH = 3.7, [HBMPPT] = 3.0 x 10-2, and [DPPHEN] = 2.7 x 10-3.

A preliminary evaluation of microporous hollow fiber membrane modules for the liquid-liquid extraction of actinides

Abstract Microporous hollow fiber (MHF) membrane modules provide an inexpensive, low-maintenance, and dispersion-free approach to continuous-flow liquid-liquid extraction processes. This work involves analyzing the potential for using these modules for process-scale metal separations such as radioactive waste stream cleanup and environmental remediation. In this work, MHF modules are used to remove neodymium (a surrogate for americium) from 2 M nitric acid using DHDECMP [dihexyl N , N -diethylcarbamoylmethylphosphonate] and CMPO [ n -octyl(phenyl)- N , N -diisobutylcarbamoylmethylphosphine oxide] as extractants in diisopropylbenzene. The modules are also used to concentrate the neodymium from the organic by back-extracting it into 0.01 M nitric acid. The performance of this technology is discussed in terms of the number of theoretical equilibrium extraction stages provided by each module, as well as how the modules extraction and back-extraction capabilities are affected by different aqueous and organic flow rates, and by the different extractants.

THE SYNTHESIS AND ACTINIDE AND LANTHANIDE COMPLEXATION OF“ SOFT” DONOR LIGANDS: COMPARISON BETWEEN 4-BENZOYL-2,4-DIHYDRO-5-METHYL-2-PHENYL-3H-PYRAZOL-3-THIONE ( HBMPPT) AND 4-THIOBENZOYL-2,4-DIHYDRO-5-METHYL-2-PHENYL-3H-PYRAZOL-3-ONE ( HTBMPP) WITH TRI-n-OCTYLPHOSPHINE OXIDE (TOPO) SYNERGIST FOR Am( III) AND Eu( III) EXTRACTION

ABSTRACT A comparison study between two “ soft” donor ligand isomers, 4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione ( HBMPPT) and 4-thiobenzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-one ( HTBMPP), both with tri-n-octylphosphine oxide ( TOPO) synergist in toluene, is reported for the extraction of Am( III) and Eu(UI). The more stable ligand, HBMPPT, gave no detectable extraction, but when HBMPPT and TOPO were combined, substantial extraction occurred with selectivity for Am( UI) over Eu( III) in three acid systems HC1, HCIO4, and HNO3. A maximum separation factor ( SF = DAm/ DEu) of 125 was obtained at pH 3.0 for the HBMPPT/ TOPO/ HCIO4 system. The other less stable ligand isomer, HTBMPP, did extract Am( m) to a small extent but combination with TOPO greatly enhanced the extraction. A maximum SF of 15 at pH 3.0 was observed for the HTBMPP/ TOPO/ HCIO4 system. Comparison of HBMPPT/ TOPO among the acids studied indicated different extraction mechanisms in the linear region in each system f...

Uranium/technetium separation for the UREX process - synthesis and characterization of solid reprocessing forms

Abstract In the context of the demonstration of the UREX (uranium extraction) process, a separation of uranium and technetium using an anion exchange resin was performed on a simulant solution containing 98.95 g/L of 238U and 130.2 mg/L of 99Tc. After sorption on the resin, TcO4− was eluted with NH4OH, the eluting stream was treated, and the technetium converted to Tc metal (yield=52.5%). The purity of the compound was analyzed: it contains less than 23.8 μg of 238U per gram of 99Tc. Tc metal was characterized by X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) spectroscopy; EXAFS analysis clearly confirms the hexagonal structure of the metal obtained after treatment. Uranium was converted to ammonium diuranate and to U3O8 in a yield of 88.2%, analysis indicates that the compound contains less than 0.16 μg of 99Tc per gram of ammonium diuaranate.

Preconcentration of low levels of americium and plutonium from waste waters by synthetic water-soluble metal-binding polymers with ultrafiltration

A preconcentration approach to assist in the measurement of low levels of americium and plutonium in waste waters has been developed based on the concept of using water-soluble metal-binding polymers in combination with ultrafiltration. The method has been optimized to give over 90% recovery and accountability from actual waste water.

SYNERGISTIC EXTRACTION STUDIES OF Am(III) AND Eu(III) FROM PERCHLORIC ACID WITH 4-BENZOYL-2,4-DIHYDRO-5-METHYL-2-PHENYL-3H- PYRAZOL-3-THIONE (BMPPT) AND TRI-n-OCTYLPHOSPHINE OXIDE (TOPO) IN BENZENE

ABSTRACT The extraction of Am(III) and Eu(III) from aqueous HCIO4 by BMPPT and TOPO in benzene was studied. The ligand BMPPT gave no detectable extraction in the ranges studied, but when BMPPT and TOPO were combined, a synergistic extraction was observed with a selectivity for Ara(III) over Eu(III) (KdAm = 7.5, Am/Eu = 68, pH 3.0, 0.01 M [TOPO], 0.30 M [BMPPT]). The slope of the acid dependency for Eu and Am was 1.6 ± 0.1 and 2.7 ± 0.1, respectively, over the pH range of 2 to 3.The slope of the BMPPT dependency was 2.7 ± 0.1 and 2.8 ± 0.1 over a 2- and 20-fold concentration range for Eu and Am, respectively; the slope of the TOPO dependency was 2.0 ± 0.1 and 2.2 ± 0.1 for Am and Eu, respectively, over a 20-fold concentration range.

Syntheses of some new polyaminocarboxylate and CMPO calix[4]arene chelators for the selective extraction of actinide ions

The syntheses of two new calix[4]arene derivatives designed for the selective liquid-liquid extraction of actinide ions have been achieved. The first, is a novel organic soluble calix[4]arene chelator 2 having four iminocarboxylate ligand moieties anchored to the lower rim. The second calix[4]arene derivative 3 that has been readily synthesized has four CMPO ligand groups tethered to the lower rim. Preliminary studies show that both 2 and 3 extract thorium(IV) more efficiently than europium(III) under acidic conditions into chloroform.

Technetium chemistry in the fuel cycle: combining basic and applied studies.

Technetium is intimately linked with nuclear reactions. The ultraminute natural levels in the environment are due to the spontaneous fission of uranium isotopes. The discovery of technetium was born from accelerator reactions, and its use and presence in the modern world are directly due to nuclear reactors. While occupying a central location in the periodic table, the chemistry of technetium is poorly explored, especially when compared to its neighboring elements, i.e., molybdenum, ruthenium, and rhenium. This state of affairs, which is tied to the small number of laboratories equipped to work with the long-lived (99)Tc isotope, provides a remarkable opportunity to combine basic studies with applications for the nuclear fuel cycle. An example is given through examination of the technetium halide compounds. Binary metal halides represent some of the most fundamental of inorganic compounds. The synthesis of new technetium halides demonstrates trends with structure, coordination number, and speciation that can be utilized in the nuclear fuel cycle. Examples are provided for technetium-zirconium alloys as waste forms and the formation of reduced technetium species in separations.