Heavy Water System Research Articles

Emulsion Characterization of the Heavy Oil-Alkaline Water System in Alkaline Flooding Mechanism Investigation Using a Combination of Modified Bottle Test and Sandpack Flooding

Due to the diversity of alkali categories and reservoir conditions, the varied oil recovery driving mechanism of alkaline flooding is subjected to different types of emulsion generation. In this study, a modified bottle test method that assesses major emulsion type formation for preliminary prediction of alkaline flooding performance in oil recovery is introduced. The modified method considers the necessary energy input required for mixing immiscible bulk phases at low interfacial tension (IFT) regions to improve the representativity of emulsion formation in the bottle test to that of in porous media. To accurately evaluate the emulsion type and phase volume distribution from the bottle test, each emulsion phase after aging in the test bottle was sampled and its water content was measured through Karl Fischer titration. Afterward, material balance calculations other than pure volume observation were applied to quantify the emulsion volume and determine the major emulsion type formation. It is found that the majority of emulsion effluent type from the sandpack flooding test were in agreement with the bottle test forecast which proved the feasibility of the modified bottle test method. The statistically optimized experimental designs were implemented due to the simplicity of the new bottle test method and it considerably cut the time expense regarding the alkaline flooding performance prediction. The high versatility of the modified bottle test ensures that the alkali usage is not limited to the inorganic alkalis mentioned in this study; other type of alkaline solutions can also be used for further expanding the scope of its application.

Hydraulic design of an advanced second shutdown system for a research reactor

There has been a significant increase in the demand for nuclear safety around the world. Safety concerns are less major for research reactors than for commercial reactors owing to their low operating temperature and power. Because most research reactors do not have a second shutdown system for the shutdown of the core, damage to the core may occur upon failure of the shutdown system. Recent research on aspects, such as utilization of radiation isotopes and neutron utilization fields, has increased the demand for high-power research reactors. This has led to the development and extensive application of the second shutdown system for research reactors. This study analyzes the hydraulic design of the heavy water dump system (HWDS) using the instantaneous dump of the heavy water reflector for the research reactor. It also investigates the hydraulic phenomena in the heavy water system that can be generated by the HWDS. The analysis was conducted on the several parameters namely, three design candidates of HWDS, piping size, valve type, dumping height, and valve running time, using the MARS-KS system analysis code. Results were used to assess the major factors affecting the system performance. An optimal design was developed to minimize the amount of stagnant heavy water in the dumping pipe and ensure that the dumping time was within 15 s. The findings of this study are applicable to research reactors that do not have a second shutdown system and to the next-generation research reactors, and are expected to contribute in enhancing the safety of research reactors.

Transient behaviors of heavy water reflector system during postulated initiating events (PIEs)

This study investigates the transient thermal-hydraulic behaviors of a heavy water reflector system during various postulated initiating events (PIEs). The following events are considered in the analysis: (1) loss of heavy water system (HWS) flow, (2) heavy water leakage, (3) loss of secondary cooling flow, and (4) dilution of heavy water. The sequence of each event is described, and thermal-hydraulic parameters such as the heavy water temperature, system pressure, flow rate, and heavy water level are monitored. To regulate the HWS, the heavy water temperature at the outlet of the heavy water vessel, the heavy water level in the expansion tank, and the flow rate in the HWS are used as the reactor regulating system (RRS) setbacks. In the event of loss of HWS flow, the standby pump kicks off to recover it, and none of the RRS setback signals are triggered. In the event of heavy water leakage, a low-level RRS setback signal trips the reactor, and the temperature rise in the HWS is not significant. The total amount of heavy water leakage with a break at the outlet of the heat exchanger is approximately 550 L. In the event of loss of secondary cooling flow, a high-temperature RRS setback signal trips the reactor. In the event of heavy water dilution, a low-level RRS setback signal trips the reactor. In the case of a pipe rupture at the highest point in the HWS inside the pool, the RRS setback signal is triggered at 83.9 s from the initiation. At the instant of the reactor trip, the reactor power increases to 150% of full power because of the degraded purity of the heavy water––95.7%. For the event of heavy water dilution, a reactor protection system (RPS) setback such as the reactor power difference between a neutron detector and a gamma detector should be used to trip the reactor.

Ultracold neutron source at the PULSTAR reactor: Engineering design and cryogenic testing

Construction is completed and commissioning is in progress for an ultracold neutron (UCN) source at the PULSTAR reactor on the campus of North Carolina State University. The source utilizes two stages of neutron moderation, one in heavy water at room temperature and the other in solid methane at ~40K, followed by a converter stage, solid deuterium at 5K, that allows a single down scattering of cold neutrons to provide UCN. The UCN source rolls into the thermal column enclosure of the PULSTAR reactor, where neutrons will be delivered from a bare face of the reactor core by streaming through a graphite-lined assembly. The source infrastructure, i.e., graphite-lined assembly, heavy-water system, gas handling system, and helium liquefier cooling system, has been tested and all systems operate as predicted. The research program being considered for the PULSTAR UCN source includes the physics of UCN production, fundamental particle physics, and material surface studies of nanolayers containing hydrogen. In the present paper we report details of the engineering and cryogenic design of the facility as well as results of critical commissioning tests without neutrons.

Hydrogen isotope behavior on a water–metal boundary with simultaneous transfer from and to the metal surface

To investigate the behavior of hydrogen on a water–metal boundary, a series of experiments have been performed that studied tritium permeation into a pressurized water jacket through pure iron piping, which contained approximately 1kPa of pure tritium gas at 423K, while monitoring the chemical forms of tritium. Additionally, the behavior of deuterium, which was generated on the heavy water–metal boundary and transferred to the metal, was also investigated using a pressure-proof heavy water vessel. Actual deuterium transfer through various metal piping, such as Fe, Ni, SS304, etc., was detected clearly by QMS at 423–573K. Moreover, using the above heavy water system, we have succeeded in detecting hydrogen isotopes simultaneously transferring from and to the metal surface by introducing hydrogen gas to the Ni piping after deuterium permeation from the heavy water side had stabilized.

Mobile Robotic Systems for Fragmentation of Nuclear Equipment

For liquidation of the heavy water evaporator has been applied a mobile robotic system MT 80, which had been developed, designed and constructed as a general-purpose decommissioning equipment. The heavy water evaporator as a part of the NPP heavy water system is located inside the main production unit building in Room No. 220 where the inner surface contamination is from 101 Bq/cm2 to the level of 103 Bq/cm2, dose rate up to 1.5 mGy/h and the feeding pipeline contained LRAW with high tritium content. The first step was the development of a work procedure with special focus on the elimination of activity and aerosols leaking into the environment. Special tooling was developed for application with the robot, such as hydraulic shears, circular saw, reciprocating saw, circular pipe cutter and a system for quick tool-change without direct intervention of the operators. All operations are remotely controlled on basis of visual information from four cameras, with consistent radiation protection of the operators.

Structural and Physical Changes in Ultrasound‐Assisted Frozen Wet Gluten

ABSTRACTUltrasound‐assisted freezing is a novel food‐freezing technique which is of benefit to frozen food quality. Studies of the structural and physical changes in the ultrasound‐assisted frozen wet gluten system illustrate how the ultrasound irradiation improves the frozen dough quality. The microtopography of ice crystals in frozen wet gluten was observed indirectly by scanning electron microscopy; the ice crystals were smaller and more uniform in wet gluten frozen using the ultrasound‐assisted technique than in wet gluten frozen without ultrasound. Fourier transform infrared spectroscopy was used to monitor the changes in the secondary structure of a frozen gluten heavy water system during frozen storage. It was determined that there were no noticeable changes in the structure of the wet gluten frozen using the ultrasound‐assisted technique. However, the structure of the wet gluten frozen without ultrasound became unordered. The freezable water content in the frozen wet gluten was determined by differential scanning calorimetry. Compared with conventional freezing, more water was frozen using ultrasound‐assisted freezing. Furthermore, the freezable water content in the wet gluten frozen using the ultrasound‐assisted technique did not increase during frozen storage. Ultrasonic cavitation promoted the primary and secondary nucleation of ice in the wet gluten and loosened the weak interactions between the gluten and the water. Consequently, the existence of a microstructure with small and uniform ice crystals was noted, which was determined to be beneficial with regard to reducing the deterioration of the gluten network and, hence, improving the quality of the frozen food.

Measurement of [formula omitted] dissolved in water at the Sudbury Neutrino Observatory

The technique used at the Sudbury Neutrino Observatory (SNO) to measure the concentration of 222 Rn in water is described. Water from the SNO detector is passed through a vacuum degasser (in the light water system) or a membrane contact degasser (in the heavy water system) where dissolved gases, including radon, are liberated. The degasser is connected to a vacuum system which collects the radon on a cold trap and removes most other gases, such as water vapor and N 2. After roughly 0.5 tonnes of H 2O or 6 tonnes of D 2O have been sampled, the accumulated radon is transferred to a Lucas cell. The cell is mounted on a photomultiplier tube which detects the α-particles from the decay of 222 Rn and its progeny. The overall degassing and concentration efficiency is about 38% and the single-α counting efficiency is approximately 75%. The sensitivity of the radon assay system for D 2O is equivalent to ∼3×10 −15 g U/g water. The radon concentration in both the H 2O and D 2O is sufficiently low that the rate of background events from U-chain elements is a small fraction of the interaction rate of solar neutrinos by the neutral current reaction.

Removal of Indium Turbidity from Water Using a Magnesium Ion Loaded Weak Acid Cation Exchanger and Fibrous Graphite Electrode

Indium turbidity generated due to some corrosion of indium metal used for sealing over pressure rupture device (OPRD) of a RAPS-I moderator heavy water system was found to create a high radiation exposure problem due to activation of 115In to In116m(t1/2=54 min,Eγ=>1 MeV). The removal of indium turbidity, due to the small size, weak charge, and low concentration[(ln)≈100–150 ppb] of the suspended particles, was not possible by conventional filtration or by normal ion exchange purification systems. Indium turbidity was generated and its removal was demonstrated on magnesium hydroxide precipitated weak acid cation exchanger resin bed with 97% efficiency. A fibrous graphite electrochemical cell was also tested in the laboratory for indium turbidity removal by electrosorption and was used to remove satisfactorily indium turbidity from a RAPS moderator system on an experimental basis. The results of these studies are presented.

Transmutation of Americium in a Heavy-Water Reactor

It is shown that 22.5 metric tons of americium from the spent fuel of 30 VVER reactors which operated for 30 yr can be transmuted in a 1 GW(t) heavy-water system in 103 yr using as fuel the plutonium from the same spent VVER fuel. This means that 7.5 VVER reactors (CUF = 0.85) must be maintained simultaneously for fuel storage time 30 yr (for a 3-yr fuel storage period, the number of VVER reactors maintained increases to 25). In the entire period of operation of the system, a substantial quantity of plutonium from the spent fuel is used – about 150 metric tons (with total plutonium production in VVER reactors of about 200 metric tons) and about 38 metric tons of fissioning isotopes are burned. Therefore, with up to 98% burnup of americium in the target material the conversion coefficient defined as the ratio of the mass of the americium annihilated to the mass of the spent fissioning material is about 0.57.

Kirkwood-Buff integrals in aqueous solutions of 3-methylpyridine

Small-angle neutron scattering measurements were performed on 3-methylpyridine (3MP) — heavy water mixtures in the mole fraction range of 0.005–0.25 at 25 °C. The obtained zero-angle scattering intensities were used together with thermodynamic data to obtain Kirkwood-Buff integrals. Calculations for 3MP — water mixtures using thermodynamic data available in the literature indicated the inaccuracy of the excess Gibbs free energy data. The extraordinary high values of the Kirkwood-Buff integrals for the 3MP —heavy water system together with thermodynamic arguments show that first indications of the liquid-liquid phase separation can be seen already at 25 °C, which is much below the lower critical solution temperature. The analysis of the excess (or deficit) number of molecules surrounding a central one allowed us to conclude that strong clustering occurs in the mixture.

Measurements of 129I in a nuclear power reactor by accelerator mass spectrometry

The method of accelerator mass spectrometry is applied to measurements of concentrations of the long-lived volatile fission product 129I ( t 1 2 = 1.6 × 10 7 a) in the primary heat transport (PHT) system and irradiated fuel bay (IFB) of a commercial nuclear power reactor. Concentrations of (8.1 ± 1.1) × 10 12 129I atoms per gram and between 10 11 and 10 13 129I atoms/L were measured in an ion-exchange resin and in the heavy water (PHT) system, respectively. The corresponding value for the IFB system water samples was 5–6 × 10 12 129I atoms/L. These measurements, based on very small size samples (of the order of 0.5 mL) emphasize the advantage of the present method where a simple chemical process for the iodine extraction enables a direct measurement of the 129I atom content of the samples. In view of the physical and chemical properties of iodine and their important implications in the environment, the method is likely to find even wider applications for the monitoring of 129I and the study of long-range nuclear waste storage.

Nematic–lamellar tricritical behavior and structure of the lamellar phase in the ammonium pentadecafluorooctanoate (APFO)/water system

2H NMR spectroscopy has been used to map a high-resolution (±0.04 K) phase diagram for the ammonium pentadecafluorooctanoate(APFO)/heavy water system. It is qualitatively similar to that for the CsPFO/heavy water system. In particular, it exhibits a discotic micellar nematic phase N+D intermediate to an isotropic micellar solution phase I and a lamellar phase for weight fractions of APFO between 0.395 (φ=0.278) and 0.589 (φ=0.455) and temperatures between 292.10 and 338.10 K. The N+D to lamellar transition crosses over from second to first order behavior at a tricritical point similar to the superfluid transition in 3He/4He mixtures. X-ray scattering experiments shows there to be no dramatic change in the structure of the micelle at the I to N+D and the N+D to lamellar transitions. Nematic order parameters (orientational order parameters of the discoidal micelles) have been calculated from electrical conductivity measurements. Their variation with temperature in the nematic phase and across the nematic to lamellar transition are qualitatively consistent with the behavior expected for thermotropic calamitic liquid crystals undergoing an isotropic to nematic to smectic-A sequence of transitions. It is, therefore, concluded that the transition from the N+D to the lamellar phase solely involves the propagation of long range positional ordering of the discoidal micelles into planes along the nematic director, that is, the lamellar phase is a discotic lamellar phase LD. This result reinforces previous claims about the structure of the lamellar phase of the CsPFO system as opposed to the alternative scenario of a classical lamellar phase in which the bilayers are perforated by microscopic defects. This conclusion is supported by measurements of 2H quadrupole splittings of heavy water. Similar measurements for deuterated ammonium ions show a preference for counterion binding to sites of lowest surface curvature. The fraction of counterions bound to the surface of the micelle is shown to increase as the temperature is lowered due to a growth in diameter and associated changes in surface curvature.

Theoretical Variations in the Concentration of Tritium in the Heavy Water in CANDU Reactors Caused by the 3He(n,p)3H Reaction

In heavy water reactors, tritium is formed by the (n,γ) reaction on deuterium and by the (n,p) reaction on the tritium decay product 3He. The relative contribution of the latter reaction depends on the retention time of 3He in the heavy water system. If the retention is at least 10 days, then, with an effective neutron flux of 1014 cm−2·s−1, the activity of tritium produced by the 3He reaction is at least 4% of that produced by the deuterium reaction after operation for 5 yr and is at least 22% after 30 yr. Complete retention of the 3He would result in similar contributions from both reactions to the concentration of tritium in a heavy water system after 30 yr.

Solvent deuterium isotope effect on hydrolysis of boric acid

The hydrolysis equilibria of boric acid in light- and heavy-water solutions containing 3 mol dm −3 of LiClO 4 as an ionic medium were studied at 25°C by measuring the lyonium ion concentration with a glass electrode. Analysis of the e.m.f. data indicated the formation of analogous complexes in H 2 O and D 2 O: B(OL) 4 − , B 4 (OL) 14 2− , and either B 2 (OL) 7 − or B 3 (OL) 11 2− as a minor species. The formation constants ∗ β p,q are smaller in D 2 O than in H 2 O. These results are consistent with those previously reported for the hydrolysis of cations. It seems that the formation constants K p , q for the heavy-water system have slightly larger values than those for the light-water system, although this solvent deuterium isotope effect for polyborate complexes is much smaller than that observed for some metal ion hydrolysis species.

Notizen: Solvent Deuterium Isotope Effect on Hydrolysis of Nd3+ Ion

The hydrolysis equilibria of Nd3+ ion in light- and heavy-water solutions containing 3 mol dm-3 (Li)ClO4 as an ionic medium were studied at 25 °C by measuring the lyoniumion concentration with a glass electrode. Analysis of the emf data indicated the formation of only the mononuclear complex Nd(OL)2 + in both light and heavy water. The formation constant *β2,1 was smaller in D2O (log *β2,1 = —16.54 ± 0.04) than in H2O (log *β2,1 = —15.90 ± 0.06). The formation constant K2,1 for the heavy-water system (log K2,1 = 12.28) had a larger value than that for the light-water system (log K2,1 = 11.86).

Measurement of the diffusion coefficient in the concentrated phases of the soap-water system by nuclear magnetic resonance.

A MEASUREMENT of the lateral diffusion coefficient of spin labels in lecithin bilayers has been reported by McConnell et al.1. This diffusion is found to be rapid, the consequences of which, in terms of the structure of biological membranes, cannot be overlooked. Here we report the result of nuclear magnetic resonance measurements on the diffusion coefficient in the concentrated phases of the potassium laurate–heavy water system. Our results strengthen the theory that diffusion in lipid water systems is rapid, magnetic resonance measurements have the advantage that it is the diffusion of the constituent molecule itself that is being observed and not the diffusion of an added “impurity” as is the case with spin fabel experiments.

Stereospecific catalytic labelling of amino-acids and mandelic acid with isotopic hydrogen.

A COMPARISON has been made between the catalytic labelling1 of organic compounds with deuterium and tritium and radiation-induced techniques2. Of fundamental importance in deciding the choice of method, particularly for tracer applications, is the possible change in configuration which may occur during substitution by isotopic hydrogen. In radiation-induced procedures, a preference for retention of configuration has been observed in crystalline systems such as the octyl phthalates3 and inositols4, whereas a predominance of inversion occurs in the liquid octanols and inositol ethers5 and in simple amino-acids6. In the catalytic technique, results from the only heavy-water system studied show that, in optically active lactic acid, deuteration of the opposition is generally accompanied by inversion7.

半均質炉と水性均質炉の開発研究

Studies on a high temperature gas cooled reactor with semi-homogeneous fuel were started in JAERI in 1958, when this reactor concept was taken up.Liquid bismuth as well as helium were considered as coolant. The main items of study under the JAERI program are described. An aqueous homogeneous reactor program in past several years is also reviewed. The main activities were critical experiments and analyses of a homogeneous heavy-water system, studies on behavior of a thorium oxide slurry and preliminary mock-up experiment for a boiling slurry reactor concept.

Formation of Gaseous Detonation Waves. A Comparison of the Knallgas-Steam and Heavy Knallgas-Heavy Water Mixtures.

Data for the formation of detonation waves in the heavy knallgas-heavy water system at 100 deg C utilizing spark ignition (360 millijoules) in a 1-in. ID reactor of 13-foot length are presented. Formation of detonation in this system differs markedly from the knallgas-steam system at comparable conditions. These differences cannot be accounted for by the relative reaction rates of deuterium and oxygen as compared to hydrogen and oxygen. The data seem to indicate that heavy water acts not only as a diluent but as a more active inhibitor than steam. (N.W.R.)