Plutonium Solutions Research Articles

Hafnium(IV)-nitrilotriacetate and hafnium(IV)-fluoride complexes investigated using an ion-selective electrode

Models of plutonium solution chemistry in vivo require formation constants which are difficult to obtain but hafnium(IV) is biochemically similar t

Controlled-potential coulometric determination of plutonium with concurrent correction for a second reversible couple : Application to solutions containing plutonium and iron or neptunium

The controlled-potential coulometric determination of plutonium with a concurrent measurement of an interfering reversible couple is described. Sample electrolysis over two different potential spans is used. The Nernst equation is utilized to determine the fraction electrolyzed for the plutonium and the interfering reversible couple for each potential span. Two linear equations, in two variables, each containing the appropriate data from one of the sample electrolyses are solved simultaneously for the quantities of plutonium and interfering reversible couple present. Appropriate background current corrections are discussed. This concurrent measurement technique has been applied to the determination of plutonium in solutions containing either plutonium and iron or plutonium and neptunium with a reliability of better than 0.1% for plutonium.

Determination of uranium and plutonium in solution by energy-dispersive X-ray fluorescence analysis

プルトニウム分析用としてグローブボックスを備えたエネルギー分散型蛍光X線分析装置を用いてL系列のX線を測定することにより,硝酸系において,100μg/ml～5mg/mlのウラン及び500μg/ml～5mg/mlのプルトニウムが定量できる.又硝酸鉛(II)を内部標準として用いることにより,ウランで200mg/ml,プルトニウムで20mg/mlまで定量範囲が広がり,同時に共存する酸の影響も補正できる.

Long-term 238Pu and 239Pu Retention and Organ Distribution in Mice at Low Doses

The 238Pu and 239Pu distribution in femur, liver, kidneys and testes and the retention function in the skeleton and liver have been studied in about 50 (C57 BL × C3H) F1 male mice. Groups of about 5–10 male mice were sacrificed from 10 to 800 days postinjection to cover their entire life span. All animals were injected intravenously with monomeric solutions of plutonium (1% trisodium citrate at pH 6.5) at doses of the order 7–15 kBq/kg body weight. The low levels of plutonium have been measured by direct counting in the entire animals and by radiochemical methods in the various tissues and organs. Significant differences between 238Pu and 239Pu were not observed at the injected doses used. The following proportions of the injected doses are retained in mice at the end of their life span: 12% in the skeleton, 0.7% in the liver, 0.1% in kidneys and 0.06% in gonads. Furthermore, the data have shown that (1) the long-term component of the plutonium skeleton retention in mice has a biological half-time that is much longer than their average life span; and (2) the long-term component of the plutonium liver retention in mice has a biological half-time of about 350 days.

Long-term 238Pu and 239Pu retention and organ distribution in mice at low doses.

The 238Pu and 239Pu distribution in femur, liver, kidneys and testes and the retention function in the skeleton and liver have been studied in about 50 (C57 BL X C3H) F1 male mice. Groups of about 5-10 male mice were sacrificed from 10 to 800 days postinjection to cover their entire life span. All animals were injected intravenously with monomeric solutions of plutonium (1% trisodium citrate at pH 6.5) at doses of the order 7-15 kBq/kg body weight. The low levels of plutonium have been measured by direct counting in the entire animals and by radiochemical methods in the various tissues and organs. Significant differences between 238Pu and 239Pu were not observed at the injected doses used. The following proportions of the injected doses are retained in mice at the end of their life span: 12% in the skeleton, 0.7% in the liver, 0.1% in kidneys and 0.06% in gonads. Furthermore, the data have shown that (1) the long-term component of the plutonium skeleton retention in mice has a biological half-time that is much longer than their average life span; and (2) the long-term component of the plutonium liver retention in mice has a biological half-time of about 350 days.

The Measurement of Eta and the Limiting Concentration of 239Pu in Critical Aqueous Solutions

Experiments were performed with a 122-cm-diam sphere to determine criticality of aqueous solutions of plutonium in a system having low-neutron leakage. The plutonium in the chemical form of Pu(NO3)4 had a 240Pu content of 2.52 wt%. The critical-sphere concentration obtained in this experiment was analyzed along with data from eight additional critical experiments to evaluate the minimum critical concentration for plutonium. The limiting critical concentration was determined to be 7.62 g Pu/ℓ, for Pu(NO3)4 without excess acid and 7.59 g Pu/ℓ for a 239Pu-water mixture. From these data, the Maxwellian-averaged thermal value of the number of fission neutrons emitted per neutron absorbed by 239Pu, eta, was determined to be 2.056 ± 0.037. The value at 2200 m/s is 2.100 ±0.041.

Automated In-Line Measurement of Plutonium Solutions in a Plutonium Purification Process

An automated solution assay instrument (SAI) based on transmission-corrected gamma-ray measurements has been developed and installed in the Plutonium Processing Facility at the Los Alamos National Laboratory. The instrument was designed for rapid, nondestructive assay of plutonium process solutions over a wide range of concentrations (0.05 to 500 g Pu/l, with 10/sup -4/ to 5 g Am/l) and for routine operation by process technicians who lack instrumentation experience. For a 25-ml sample, the precision is 30 g Pu/l within a 1000-s assay and 4 g Pu/l within a 2000-s assay. The results of test and evaluation demonstrate that the SAI is a reliable and accurate instrument for assaying plutonium process solutions.

A Description of the Chemistry of Aqueous Solutions of Uranium and Plutonium to 200°C Using Potential-pH Diagrams

Potential-pH diagrams are reported for uranium and plutonium in water containing carbonate, chloride, fluoride, phosphate, sodium, and sulfate ions at 25, 100, and 200°C. Complexation was considered in deriving the diagrams and the potential-pH relationships were calculated for various total dissolved ion concentrations. The diagrams are used to analyze the general features of the thermodynamic behavior of uranium and plutonium in geological systems and to help identify processes that might be expected to occur in the vicinity of a deep underground vault for nuclear fuel waste.

AUTOSEP, an automated system for the quantitative ion exchange separation of plutonium from impurities

The anion exchange separation of interfering impurities from plutonium in the Dowex-1 8 N HNO3 system is a reliable purification method. An automated system, AUTOSEP, based on this manual procedure has been developed for greater productivity. Samples, in groups of ten, each containing 5–10 mg of plutonium are processed automatically in this system. AUTOSEP incorporates a means of programming reagent delivery, adjustment of the sample to the plutonium (IV) oxidation state via Fe(II) reduction/HNO3 oxidation, plutonium sorption on the resin in 8 N HNO3, washing of the resin bed with 8 N HNO3 to remove impurities, elution of the purified plutonium with 0.36 N HCl–0.01 N HF, and waste effluent disposal. The reagents are delivered by gravity from a module whose only moving parts are rotary valves. The eluted plutonium solutions are collected for subsequent controlled-potential coulometric analysis. The average recovery of plutonium determined by controlled-potential coulometry using this apparatus was 100.00% with a relative standard deviation of 0.10%.

Plutonium Retention in Mice and Rats after Gastrointestinal Absorption

The effects of oxidation state and administration medium on the retention of plutonium were studied following oral administration of plutonium to mice and rats. The weight concentration of plutonium in the solutions administered (1 x 10-'0 g/ml) was that for 239Pu at its maximum permissible concentration in drinking water, 5 pCi/ml; the administered solutions contained hexavalent and tetravalent plutonium in 0.01 M bicarbonate to simulate the compositions of treated (chlorinated) and untreated drinking water, respectively, and tetravalent plutonium in 0.01 M nitric acid and 0.17 M citrate to provide retention data that could be compared with those obtained in earlier investigations. The retention of plutonium was found to be essentially independent of its oxidation state and the medium in which it was administered. The mean of the values obtained in the mouse was 0.2% and in the rat was 0.3%. These values are two orders of magnitude higher than those obtained in earlier investigations when rats were administered 0.01 M nitric acid solutions of tetravalent plutonium. The particular significance of this difference in results is that the data obtained from the earlier investigations were basic to the establishment of a gastrointestinal absorption factor for plutonium in man, and this factor was in turn used to set the MPC for plutonium in drinking water.

The chemical thermodynamics of nuclear materials—V: The enthalpy of solution of alpha and delta-stabilized plutonium in 6M HCl

The enthalpies of solution of alpha phase plutonium and delta phase plutonium (stabilized with 2.95 atomic percent gallium) in 5.998 M HCl have been determined using a modified LKB reaction calorimeter. The enthalpy values obtained at 298.15 K are (−592.17 ± 1.02) kJ mol −1 for the alpha phase and (−577.17 ± 1.05) kJ g-formula −1 for the delta phase, respectively. These results enable the calculation of the enthalpy of formation of the plutonium-gallium alloy as (−2.25 ± 1.56) kJ g-formula −1.

Nuclear track registration from solution media: Alpha track registration in solid state track detectors in solutions of actinides

The results are reported of a study on various aspects of registration and revelation of alpha tracks in the three most commonly used cellulose nitrate detectors (namely LR 115, Ca 80-15 and Daicel) immersed in solutions of actinide elements. Americium, plutonium and enriched uanium in dilute nitric acid solution were used as alpha sources. Experimentally determined values of K wet (a measure of the efficiency of track registration from solution) are around 2–5×10 −4 cm for the three detectors under various conditions of exposure and etching. These values have been examined in the context of the range of the particle, its energy loss rate in the solution medium and the sensitivity of the detectors. Optimum conditions of track registration and revelation for the analytical applications of the technique have been experimentally established. Linear relationships were obtained between the concentrations of uranium or plutonium in the solution and the number of tracks per cm 2 obtained under uniform experimental conditions of exposure and etching.

Oxidation state of plutonium in the Irish Sea

SEVERAL of the chemical parameters needed to understand the distribution and behaviour of plutonium in the aquatic environment have not been fully investigated in the field. We consider here two of the more fundamental of these parameters: (1) the oxidation state(s) of the plutonium present in seawater; and (2) the extent to which each oxidation state is associated with suspended particulate matter. A widely accepted analytical technique is adapted to separate the two oxidation states expected to show a high affinity for particulate matter, Pu(III) and Pu(IV), from the more soluble pair, Pu(V) and Pu(VI), and is applied to a series of seawater samples. It was found that in the area studied, generally >75% of the plutonium in solution, and <10% of the plutonium on particulate matter, was Pu(V + VI); consequently the distribution coefficients for Pu(III + IV) exceeded those for Pu(V + VI) by more than two orders of magnitude.

The half life of 239Pu: By specific activity measurements and by mass spectronetric determination of daughter growth

Two nearly independent methods have been used for measuring the half life of 239Pu. In one, the alpha-particle activity of a known mass of plutonium of known isotopic composition (>99.9% 239Pu) was measured using a defined-solid-angle alpha-particle counter; the other method involved measuring the mass of the daughter 235U grown into a known mass of 239Pu, using isotope-dilution mass spectrometry with 233U and 238U as independent spikes. The concentrations of the plutonium solution and of the two uranium spike solutions were measured by oxidation-reduction titration. The mean half-life value determined by alpha-particle counting was 24,124.2±13.6yr and that determined by isotope-dilution mass spectrometry was 24,138.6±13.7yr, giving an overall average value of 24,131±16yr. (The uncertainties are one standard deviation.)

Plutonium Activities in Soil Solutions and the Stability and Formation of Selected Plutonium Minerals

AbstractSelected thermodynamic data was used to develop solid phasesoil solution equilibria diagrams which are used to predict and understand plutonium behavior in terrestrial environments.The plutonium mineral transformations in soils are highly dependent upon the pH, Eh, and the soil solution composition. The predictions of weathering and formation sequences of Pu(OH)3, Pu(OH)4, PuO2(OH), PuO2(OH)2, PuO2, βPu2O3, PuF3, PuF4, PuO2CO3, and Pu(HPO4)2 at pH values from 3 to 11 at pO2 from 0.68 to 80, and in an assumed weathering environment are given. The study shows that the PuO2 is the most stable mineral in the pH and pO2 ranges found in the terrestrial environments.The nature and activity of ions and ion‐complexes and, hence, the total plutonium in solution is a function of the stable phase, pH, Eh, and complexing anions: for example, (i) in a reducing environment (pO2 80) at pH 8 and in equilibrium with PuO2(s), the predominant solution species are Pu3+ and its complexes, and (ii) in an oxidizing environment (pO2 16) at pH 8 and in equilibrium with PuO2(s), the predominant solution specie is PuO2CO3OH−.Empirical predictions regarding the plutonium sorption by soils are outlined and verified by experimental results reported in the literature. The deficiencies in the present thermodynamic data and future research needs are outlined.

Application of fission track registration technique in the estimation of fissile materials

Analysis of fissile materials in solution by fission track registration technique has been extended to plutonium in solution of its alloys. In these estimations, the results agreed within 1–4% with the average of those obtained by other chemical and instrumental methods like potentiometry, mass-spectrometry and X-ray fluorescence. Some special practical problems encountered in the analysis of plutonium solutions are noted. Various factors affecting the results have been investigated and the necessary precautions for reducing these errors have been indicated. The advantages of the method over some other conventional methods have also been discussed. It is suggested that a source of about 10 μg of252Cf corresponding to a neutron flux of about 107 n·cm−2·sec−1 is ideal for these experiments.

Distribution and Excretion of Three Chemical Species of 239Pu(IV) in the Beagle

The early retention and distribution of 239Pu in the beagle were compared following intravenous administration of 239Pu(IV) as the transferrin complex (Pu-Tf), as a plutonium complex in citrate buffer (Pu-Cit) of pH 3.5 and as a particulate Pu(IV) in colloidal form (Pu-P). The early distribution and retention of Pu(IV) at 14 days after injection of Pu-citrate and pu-transferrin were indistinguishable. There was a difference in urinary excretion patterns. Deposition, microdistribution and retention after administration of a suspension of particulate Pu(IV) differed greatly from those seen in dogs injected with true solutions of plutonium. After injection of Pu-Tf or Pu-Cit, the nuclide was cleared from circulation at a slow rate. Approximately 30% was deposited in the liver, ∼50% in the skeleton and ∼2% in other soft tissues. Pu-P left the circulation at a very fast rate, ∼70% was deposited in the liver, with only 2% in the bone and ∼24% in other soft tissue. Only an insignificant fraction of the injected Pu-P was excreted. In the liver, the microdistribution after injection of Pu-Tf and Pu-Cit was uniform and Pu(IV) was associated first with soluble protein and later transferred to subcellular liver particles. After injection of Pu-P the microdistribution was heterogeneous; most of the Pu(IV) was located in R. E. cells and little was associated with soluble proteins. After injection of Pu-Cit and Pu-Tf, Pu(IV) was found on bone surfaces, whereas after injection of Pu-P, the small amount of Pu(IV) present was located exclusively in macrophages of the bone marrow.

Plutoniumbestimmung Nach Seiner Abtrennung von Uran und den Spaltprodukten

Methods are described for the electrochemical and spectrophotometrical determination of poor solutions of plutonium. The possibility was examined to use these methods also for the determination of plutonium in irradiated reactor fuel. Results of the spectrophotometrical determination of plutonium with Arsenazo III after its extractionchromatographic separation from solutions of burned up reactor fuel of the reactor types WWR-S and WWER-2 are given.

Response to “The Influence of Neutron Poisons on High-Concentration Plutonium Solutions”

"Response to “The Influence of Neutron Poisons on High-Concentration Plutonium Solutions”." Nuclear Science and Engineering, 55(4), pp. 483–484

Plutonium Fuel Technology, Part III: Nuclear Criticality Safety Considerations in LWR (Pu,U)O2Fuel Fabrication

The nuclear criticality safety aspects of light water reactor (Pu,U)O2 fuel fabrication have been reviewed. Conclusions are as follows: 1. Criticality safety limitations will present a major design challenge in those parts of the plant where plutonium and plutonium-uranium solutions are processed. In particular, the requirement of large vessel volume to achieve homogeneous plutonium-uranium blending will be complicated by the restrictive criticality safety limits necessary on vessel dimensions. Special vessel design, such as annular geometry, and fixed nuclear poisons are possible innovations to overcome this problem.2. Once the PuO2 and UO2 are mixed and in dry powder form, plant throughput should proceed at a reasonable rate and criticality safety will not necessarily limit operations.3. In dry operations, radiation protection limitations are likely to be more restrictive than criticality safety limitations. In other words, criticality safety limits will not be determining factors for process control, s...