Reprocessing Of Fuels Research Articles

129I in Swedish rivers: distribution and sources

We analyzed the concentration of 129I in the water of 26 rivers covering most of the runoff from Sweden, with the aim of assessing current contamination levels, distribution patterns and potential sources in freshwater systems of northern Europe. The results show relatively high values (up to 1.4×10 9 atoms l −1), steeply decreasing levels with increasing latitude and a positive correlation with Cl concentration and other chemical parameters. The 129I concentrations observed in south Sweden are probably the highest ever recorded in rivers without any direct discharge from a nuclear installation. The strong latitudinal dependence suggests a northward dilution and possibly depletion of the isotope and a transport from a source located to the south. The most plausible source of the 129I in the studied rivers is atmospheric fallout of 129I emitted either by atmospheric discharges from the nuclear reprocessing facilities at Sellafield (England) and La Hague (France) or by volatilization from seawater contaminated by the same sources. The question is now whether and at what rate the 129I concentration in Nordic watersheds will increase further if discharges from nuclear reprocessing continue.

Applicability of a Model Predicting Iodine-129 Profile in a Silver Nitrate Silica-Gel Column for Dissolver Off-Gas Treatment of Fuel Reprocessing

The applicability of a mathematical model predicting iodine-129 profile in a silver nitrate silica-gel (hereinafter referred to as Ag-S) column for radioactive iodine treatment was examined using actual off-gas from a dissolution step of a spent nuclear fuel reprocessing test rig, where PWR spent fuels with burnups up to 44,000 MWdt−1 were dissolved. The iodine-129 profile predicted by the model showed good agreement with the iodine profile obtained in the experiment. It was suggested that the model would be useful to predict iodine profiles in an Ag-S column operated at 423 K for the off-gas treatment of actual spent fuel dissolution. Also, the values of the parameters used in the prediction, i.e., the effective diffusion coefficient and the Langmuir coefficient, were supposed to be applicable within the volumetric NO2 concentration range lower than 1%.

Structural effect of N,N-dialkylamide on the extraction of thorium(IV) ion from nitric acid solution

N,N-dialkylamides, (octan-, decan- and dodecanamides) having ethyl and butyl groups as alkyl substituents, were synthesized in order to investigate their selectivity and capability in the extraction of Th(IV) from acidic nitrate media (3 and 6M HNO3) in nuclear reprocessing. The distribution ratios of Th (IV) with the amides in kerosene decrease with the increase of the alkyl chain length (C8, C10, C12), probably due to steric hindrance.

シリカ担持型ピリジン基アニオン交換体の合成及び使用済核燃料再処理への応用に関する研究

シリカ担持型ピリジン基アニオン交換体の合成及び使用済核燃料再処理への応用に関する研究

Perceptual indicators of environmental health, future land use, and stewardship.

There are important linkages between the health of humans and the environment, restoration of degraded lands, and long-term stewardship of public lands, yet most environmental indicators deal only with assessing the physical and biological aspects of ecosystems. In this article, we examine the ratings of perceptions of several environmental problems for their utility as indicators of environmental quality, and examine perceptions of future land use by people interviewed in Santa Fe, New Mexico, near the Department of Energy's (DOE) Los Alamos National Laboratory (LANL). Overall, people with lower incomes rated environmental problems as more severe than others, were more willing to spend federal funds to solve them, and were consistent in their ratings of severity of environmental problems and their willingness to spend federal funds. Cleaning up LANL and other Department of Energy sites, received the highest rating for expenditure of federal funds. The highest rated future uses for DOE sites were for recreation and for National Environmental Research Parks. People with less education generally gave higher ratings to most future land uses for DOE than did those with more education. However, those with higher education gave higher ratings to nuclear reprocessing, and nuclear material storage. Where there were differences, the people interviewed at Santa Fe rated all environmental problems (except pesticides) as more severe than did those previously interviewed in Albuquerque (located farther from the LANL site), and they were more willing to spend federal funds on these problems. Ratings for all future land uses did not differ between the Santa Fe and Albuquerque respondents. These perception-based indicators show general agreement among people living close and farther away from LANL with respect to cleaning up LANL and the future land uses for the site. These indicators should be considered by regulators, site personnel, and policy makers in future management and land use decisions.

Accumulation of COGEMA-La Hague-derived reprocessing wastes in French salt marsh sediments.

Over the past five decades, authorized low-level discharges from coastal nuclear facilities have released significant quantities of artificial radionuclides into the marine environment. In northwest Europe, the majority of the total discharge has derived from nuclear reprocessing activities at Sellafield in the United Kingdom and COGEMA-La Hague in France. At the Sellafield site, a significant amount of the discharges has been trapped in offshore fine sediment deposits, and notably in local coastal and estuarine sediments, and much research has been focused on understanding the distribution, accumulation, and reworking of long-lived radionuclides in these deposits. In contrast, there are few high-resolution published data on the vertical distribution of radionuclides in fine-grained estuarine sediments near, and downstream of, COGEMA-La Hague. This paper therefore examines the vertical distribution of a range of anthropogenic radionuclides in dated salt marsh cores from two estuaries, one adjacent to, and the other downstream of, the COGEMA-La Hague discharge point (the Havre de Carteret at Barneville-Carteret and the Baie de Somme, respectively). The radionuclides examined show a vertical distribution which predominantly reflects variations in input from COGEMA-La Hague (albeit much more clearly at Barneville-Carteret than at the Baie de Somme site), and Pu isotopic ratios are consistent with a La Hague, rather than weapons' fallout, source. Because of sediment mixing, the marshes apparently retain an integrated record of the La Hague discharges, rather than an exact reproduction of the discharge history. Sorption of radionuclides increases in the order 90Sr < 137Cs < 60Co < 239,240Pu, which is consistent with Kd values reported in the literature. In general, the radionuclide activities observed at the sites studied are low (particularly in comparison with salt marsh sediments near the Sellafield facility), but are similar to those found in areas of fine sedimentation in the central Channel. These marshes are not major sinks for discharged reprocessing wastes.

129I/ 127I ratio measurements in bovine thyroids from the North Cotentin area (France)

Iodine-129 is routinely released in the gaseous and liquid low-level radioactive effluents of nuclear spent fuel reprocessing plants. Environmental impact assessment of these discharges are performed based on monitoring samples of different types of natural indicators. Thyroid is considered as a relevant organ to monitor radioactive iodine isotopes. In this study, bovine thyroids were collected in herds located in the Cotentin area under the influence of authorized low level gaseous effluents of the La Hague nuclear fuel-reprocessing plant. For low level 129I/ 127I ratios, characteristic of environmental samples (10 −12 to 10 −7), RNAA or SMA that includes important radiochemical preparation steps are used. This paper demonstrates the interest of direct γ-X spectrometry to measure 129I activities, associated to INAA to measure 127I to attain higher ratios levels (10 −6 to 10 −4). This study shows the interest of monitoring bovine thyroids considered as sentinel organs to characterize the dispersion in space and time of 129I discharged in low level radioactive gaseous effluents by the La Hague reprocessing plant.

RECOVERY SYSTEM FOR URANIUM FROM SEAWATER USING BRAID TYPE ABSORBENT

The density of uranium in the seawater is only 3.3 mg/m3, but its total amount 4.5 billion tons is 45, 000 times of annual demand of nuclear fuel in the world. The target of this study is the cost-down of the collection of theuranium from the sea to three times of the market price and cheaper than the recycle fuel by nuclear reprocessing. In this study, the high performance adsorbent deformed to the race is proposed with its mooring system, and thefeasibility of the cost down is shown in the Kuroshio influenced basin offshore the west coast of the Okinawa Island, based on the field test on the adsorption ratio of uranium and the quantity and kind of the adhered creature and the water channel test on the drag force on the adsorbent due to waves and currents.

Kinetics of the Reaction of Methyl Iodide with Hydroxylamine in an Aqueous Solution within the Framework of Nuclear Spent Fuel Reprocessing

Within the scope of investigations carried out to find a new reactant for dissolution off-gas scrubbing in spent fuel reprocessing, this paper reports the study of the reaction between hydroxylamine and methyl iodide in an aqueous solution. The products with an excess of hydroxylamine were ascribed to be iodide and N-methylhydroxylamine. The main contribution of this work was the kinetics investigations from 25 to 55 °C within a pH range of 2.2−13.6 (analytical data obtained by ion chromatography), operating conditions for which no sufficient data were available from the literature. NH3OH+ was found to be nonreactive. The NH2OH/CH3I and NH2O-/CH3I reactions, the second one having not been investigated so far, were first order with respect to each reactant, with second-order rate constants of respectively (4.30 ± 0.25) × 10-3 and (2.05 ± 0.25) × 10-1 mol-1 L s-1 at 55 °C and activation energies of 98.3 ± 3.4 and 67.4 ± 2.9 kJ mol-1. These results are consistent with estimations from a Bronsted correlation ...

Determination of 129I/127I ratios in environmental samplesusing neutron activation analysis

Studies on the behavior of 129I in the environment are greatly enhanced when the concentration of the radioiodine can be related to stable 127I. The background ratios of 129I/127I of 10-10 and lower, found in uncontaminated areas, are best measured using accelerator mass spectrometry. However, there are many examples of studies where ratios higher than 10-8 have been measured, even in places located remotely from nuclear reprocessing activities. In the vicinity of reprocessing plants it is possible to find ratios between 100 and 10-7, which can be detected easily using neutron activation analysis (NAA). Stable iodine is readily determined at concentrations below 1 mg/kg in environmental materials with instrumental NAA and radiochemical techniques can be used to measure 129I to below mBq concentrations. Therefore, where there are elevated concentrations of 129I it is possible to use a combination of neutron activation techniques to determine 129I/127I ratios. This paper describes how NAA is used to measure 129I/127I ratios in milk, vegetation, and atmospheric samples. Instrumental NAA is used to measure both 129I and 127I where the ratio is between 100 and 10-3. A radiochemical procedure is used to measure 129I at ratios between 10-3 and 10-7, with a thermal neutron flux of 1016 m-2·s-1.

N,N-Dihexyl Hexanamide: A Promising Extractant for Nuclear Fuel Reprocessing

N,N-Dialkyl amides have drawn the attention of radiochemists engaged in the development of alternate extractants to tri-n-butyl phosphate (TBP) for the reprocessing of irradiated fuels, particularly with high radiation fields and high plutonium content. Dihexyl hexanamide (DHHA) has been found to be a promising extractant in this direction. Log K ex values for the extraction of UO2(NO3)2·2DHHA and Pu(NO3)4·2DHHA in n-dodecane were found to be 1.43 and 3.62, respectively. At high nitric acid concentration (5 M), the amide undergoes protonation and extracts U(VI) and Pu(IV) as ion pairs of the type (UO2(NO3)3 −)(HDHHA+) and (Pu(NO3)6 2−)(HDHHA+)2. At trace level concentrations, the distribution coefficient (D) of Pu(IV) and U(VI) with a 1 M solution of DHHA in n-dodecane at 3.5 M HNO3 are 41.2 and 13.5, respectively. Similarly, at 50% uranium saturation of the organic phase the D values of Pu(IV) and U(VI) are 9.2 and 4.2, respectively. These results suggest the distinct advantages of DHHA over TBP in improved extraction of Pu and ease of stripping of uranium. The separation factors for 0.5 M DHHA at 30 Mrad are obtained as ∼37 (U/Zr) and ∼75 (Pu/Zr), suggesting that this extractant is particularly promising for the selectivity of Pu and U over Zr from irradiated solutions as compared to TBP. Results obtained during this work demonstrate the potential of amides in meeting the challenges posed by the large Pu content and high radiation fields encountered during the reprocessing of Pu-based fuels discharged from thermal as well as fast power reactors.

Laser Technology in Global 129I Radionuclide Measurements

Studies intended for increasing the accuracy and sensitivity in determining the 129I concentration in various gas media are carried out. The effect of the gas components of the working medium, which develops during the reprocessing of waste nuclear fuel at radiochemical plants, on the 129I fluorescence excited by radiation of He–Ne laser (633 nm) is studied. The factors strongly affecting the laser-excited fluorescence of 129I and 127I iodine isotopes in atmospheric air (frequency of the exciting radiation, the temperature of the iodine vapor, and the pressure of the analyzed gas mixture) are studied. The values of these parameters, optimal from the viewpoint of the 129I detection sensitivity, are determined. A method for measuring the 129I and 127I concentrations in atmospheric air is proposed. A laser complex for online monitoring of the 129I concentration in gases is developed. It can be used for 129I concentration measurements in working media during the reprocessing of waste nuclear fuels, making it possible to affect the technological procedure and, in particular, to improve its ecological safety. The system developed can be used for ecological monitoring of atmospheric air.

B204 FBR 燃料再処理用解体機の開発

B204 FBR 燃料再処理用解体機の開発

Status and Prospects for Spent Fuel Reprocessing Technology

Status and Prospects for Spent Fuel Reprocessing Technology

Radiochemistry in India

A major expansion in the experimental programme of Atomic Energy occurred with the establishment of Atomic Energy Establishment at Trombay (AEET). Along with the setting up of the India's first reactor APSARA, a prototype radiochemistry laboratory was set up at the Trombay site. This laboratory was to serve as a training ground for a team of chemists, chemical engineers and metallurgists in the handling of high radioactive substances. This prototype laboratory having an active area of 375 m 2 . and associated service area was fully commissioned and was operational by 1958. In view of high technology involved in the design and operation of a Class A radioactive laboratory, Dr. H. Bhabha sought the support of United Kingdom Atomic Energy Authority (UKAEA). This laboratory at south site of Trombay complex had two radioactive wings equipped with six fume hoods in each wing. In addition, there were a large number of β, γ boxes and glove boxes. There was a well equipped counting room with facilities for α and β counting and γ spectrometry with a 100 channel analyser. The experience gained during this period became useful in planning the future facilities such as plutonium laboratory at Fuel Reprocessing Plant, the Radiological Laboratories at Trombay, BARC, and similar laboratories at IGCAR. Initially, radiochemistry research programme was based on the availability of APSARA reactor for nuclear and radiation chemistry studies and plutonium, protactinium, and actinium obtained from UKAEA for research in actinide chemistry. Dr. M.V. Ramaniah who had taken over as Head, Radiochemistry Division in 1965 was the driving force for the completion and commissioning of radiological laboratories at Trombay around 1969. The chemistry wing of the new complex has 14 laboratories of size 7 × 10m, three low active laboratories of size 6 × 10m, a modern counting room equipped with state-of-the-art instruments, and an alpha tight hot cell with master slave manipulators. Each laboratory room was provided with a large number of fume hoods and glove boxes, conditioned fresh air supply with 10−12 air changes/hr, well managed liquid effluent system connecting all the laboratories and state-of-the-art health and safety devices for continuous monitoring of radioactivity. The alpha tight hot cell was commissioned for synthesis of transplutonium elements as well as burn up studies. The laboratory is equipped with a variety of modern instrumentation such as mass spectrometer, ESR spectrometer, modern spectrophotometer, thermal analyser, XRD system, and α and γ spectrometer. The area of research and development were also broadened with the availability of variable energy cyclotron at Calcutta and medium energy heavy ion accelerator Pelletron at TIFR, Mumbai. The area of research activities which are actively being carried out are (1) Nuclear chemistry, (2) Actinide and process chemistry, (3) Studies on solid state chemistry and spectroscopy of actinide and analytical spectroscopy, and (4) Training and services. This paper highlights some of the important achievements in the first two areas in brief.

A study of lanthanide complexes formed with the terdentate nitrogen ligand 4-amino-bis(2,6-(2-pyridyl))-1,3,5-triazine. Relevance to the separation of actinides and lanthanides by solvent extraction †

The terdentate ligand 4-amino-bis(2,6-(2-pyridyl))-1,3,5-triazine L4 has been shown to have useful actinide(III)/lanthanide(III) separation properties relevant to nuclear reprocessing. The complexation of this ligand with the lanthanides has been investigated. Crystallographic analyses show the formation of five structural types. In the first part of the lanthanide series, (La–Sm), these structural types are (1) [LnL4(NO3)3(H2O)2], 11-coordinate, only for Ln = La; (2) [LnL4(NO3)3(H2O)], 10-coordinate, for Ln = La, Pr, Nd, Sm; (3) [LnL4(NO3)2(H2O)3][NO3] 10-coordinate for Ln = Nd, Sm. In the second part of the series from Eu to Lu the structures are all 9-coordinate but have two different stoichiometries; (4) [LnL4(NO3)2(H2O)2][NO3] for Ln = Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; (5) [LnL4(NO3)3(H2O)] unusually with one unidentate nitrate for Ln = Yb, and Y. With M = Sc the structure obtained is [ScL4(NO3)3] which is 8-coordinate with one unidentate nitrate. The structure types found for particular lanthanides can be correlated with the size of the ion, although several of the lanthanides form two structure types. Particularly noticeable is the alternative pairing of one bidentate nitrate ion or two water molecules in the coordination sphere with a concomitant free nitrate anion in the latter case. Type 5 includes the relatively rare sighting of a unidentate nitrate anion. Extensive intermolecular hydrogen bonding involving the free amine group is found in all the structures.

Protracted nuclear export of glucocorticoid receptor limits its turnover and does not require the exportin 1/CRM1-directed nuclear export pathway.

Glucocorticoid receptors (GRs) are shuttling proteins, yet they preferentially accumulate within either the cytoplasmic or nuclear compartment when overall rates of nuclear import or export, respectively, are limiting. Hormone binding releases receptors from stable heteromeric complexes that restrict their interactions with soluble nuclear import factors and contribute to their cytoplasmic retention. Although hormone dissociation leads to the rapid release of GRs from chromatin, unliganded nuclear receptors are delayed in their export. We have used a chimeric GR that contains a heterologous, leucine-rich nuclear export signal sequence (NES) to assess the consequences of accelerated receptor nuclear export. Leucine-rich NESs utilize the exportin 1/CRM1-dependent nuclear export pathway, which can be blocked by leptomycin B (LMB). The fact that rapid nuclear export of the NES-GR chimera, but not the protracted export of wild-type GR, is sensitive to LMB, suggests that GR does not require the exportin 1/CRM1 pathway to exit the nucleus. Despite its more rapid export, the NES-GR chimera appears indistinguishable from wild-type GR in its transactivation activity in transiently transfected cells. However, accelerated nuclear export of the NES-GR chimera is associated with an increased rate of hormone-dependent down-regulation. The increase in NES-GR down-regulation is overcome by LMB treatment, thereby confirming the connection between receptor nuclear export and down-regulation. Given the presence of a nuclear recycling pathway for GR, the protracted rate of receptor nuclear export may increase the efficiency of biological responses to secondary hormone challenges by limiting receptor down-regulation and hormone desensitization.

Phenyl-N,N-dibutylcarbamoylmethyl sulfoxide as a new bifunctional extractant for extraction of uranium (VI) in toluene

A new bifunctional extractant named phenyl-N,N-dibutylcarbamoylmethyl sulfoxide (PCMSO) is synthesized and characterized in order to investigate its selectivity and capability in the extraction from acidic nitrate media in nuclear reprocessing. The extraction of uranium(VI) with PCMSO in toluene has been studied at various concentrations of nitric acid, extractant and salting-out agent (LiNO3). The mechanism of extraction is discussed in the light of the results obtained. The extracted species has also been investigated using FT-IR spectrometry. The related thermodynamic functions were calculated. The IR spectral study was also made of the extracted species.

Inhibition of Glucocorticoid Receptor Nucleocytoplasmic Shuttling by Okadaic Acid Requires Intact Cytoskeleton

It has been shown previously that glucocorticoid receptors (GRs) that have undergone hormone-dependent translocation to the nucleus and have subsequently exited the nucleus upon hormone withdrawal are unable to recycle into the nucleus if cells are treated during hormone withdrawal with okadaic acid, a cell-permeable inhibitor of certain serine/threonine protein phosphatases. Using a green fluorescent protein (GFP) GR chimera (GFP-GR), we report here that okadaic acid inhibition of steroid-dependent receptor recycling to the nucleus is abrogated in cells treated for 1 h with colcemid to eliminate microtubule networks prior to steroid addition. After withdrawal of colcemid, normal cytoskeletal architecture is restored and okadaic acid inhibition of steroid-dependent GFP-GR nuclear recycling is restored. When okadaic acid is present during hormone withdrawal, GR that is recycled to the cytoplasm becomes complexed with hsp90 and binds steroid, but it does not undergo the normal agonist-dependent dissociation from hsp90 upon retreatment with steroid. However, when the cytoskeleton is disrupted by colcemid, the GR in okadaic acid-treated cells recycles from the cytoplasm to the nucleus in an agonist-dependent manner without dissociating from hsp90. This suggests that under physiological conditions where the cytoskeleton is intact, a dephosphorylation event is required for loss of high affinity binding to hsp90 that is required for receptor translocation through the cytoplasm to the nucleus along cytoskeletal tracts.

Thirty years of fuels and materials information from EBR-II

The Experimental Breeder Reactor-II (EBR-II) was a 62.5 MWt–20 MWe sodium cooled fast reactor that was operated successfully for 30 years. Over its period of operation a wealth of fuels and materials information originated from EBR-II. Several missions were conducted in EBR-II, all of which yielded new and valuable additions to the world's knowledge base for nuclear materials. Some of the first pioneering experiments on irradiation effects in stainless steels were conducted in EBR-II. Later, practical manifestations of enhanced irradiation creep, swelling, and loss of ductility were experienced on EBR-II components. In addition, for a period of more than 15 years, the EBR-II reactor would become the primary irradiation facility for all fast reactor fuels and materials research and development. Both the initial mission and final mission for EBR-II (the Integral Fast Reactor Concept, IFR), involved the remote reprocessing and irradiation of fast reactor metallic fuels. The fuels and materials information gleaned from these missions will be summarized with the intent of portraying a sample of the valuable legacy that EBR-II contributed to the world's store of nuclear fuels and materials knowledge.