Recovery system for uranium from seawater using braid type adsorbent

Shimizu, Takao*; Tamada, Masao; Seko, Noriaki; Sakaguchi, Isamu*

Kaiyo Kaihatsu Rombunshu, 18, p.737 - 742, 2002/06

https://doi.org/10.2208/prooe.18.737

Total amount of uranium in seawater is 4.5 billion tons corresponding to 45,000 times of annual demand for nuclear fuel in the world, though its concentration is only 3.3 mg/m3. The target of this study is that the cost-down of uranium collection from the sea to three times of the market price. This price is cheaper than the recycle fuel by nuclear reprocessing. The present study proposed a high performance adsorbent made by means of both radiation induced graft polymerization and braid technique. The drag force of the braid type adsorbent in water channel was measured. In the west coast of Okinawa prefecture, the adsorption of uranium and the adhesion of sea creature were investigated. It was clarified that reduction of the drag force by the deformed braid adsorbent in the water flow, the increment of uranium adsorption owing to high temperature of seawater, and little adhesion of the creature.

Applicability of AQUA code to industrial piping flows

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PNC TN9410 96-276, 49 Pages, 1996/09

PNC-TN9410-96-276.pdf:1.82MB

Fluid flow in circular tube is the most frequently encountered in engineering fields related to thermal hydraulics. The fluid flow in straight tube has been investigated with many experiments and analyses in laminar and turbulence conditions with sufficient accuracy. In the design of plant piping, there are many contract and enlargement of flow area as well as elbows and junctions. Such a complexity of industrial piping requires fine mesh and long simulation time for the analyses of the flow. To evaluate the applicability of the AQUA code for flow analyses in an industrial piping, analyses for convection around submerged a cylinder, secondary flow with elbows and flow in a sudden contract were carried out. With the analysis of flow field around a submerged cylinder, drag force acting on the cylinder was evaluated from the numerical simulation with AQUA code. The drag force was agreed with the results using equation of drag coefficient depends on measured data in case of small friction of submerged cylinder and narrow separation region of the cylinder. In the analysis of the secondary flow with three elbows, AQUA code simulates the characteristics of secondary flow. The results showed that the secondary flow almost disappeared at point at 30d (d; diameter of pipe) distance from the elbow. The flow in a sudden contract was simulated. Ratio of the cross sectional area for pipe to the area for vessel is 0.2. In this case, effect of the contract to velocity distribution is small at the position that from inlet of the pipe to two times of the diameter in the downstream.

Study on improvement of constitutive equations and numerical methods for three-fluid model(3)

The Japan Society of Multiphase Flow*; Special Committee for Examination of Thermohydraulic Analysis Code based on Three-Fluid Model*

PNC TJ9565 94-001, 530 Pages, 1994/03

PNC-TJ9565-94-001.pdf:12.01MB

The purpose of the present study is to improve a numerical prediction method for multiphase flows based on the three-fluid model. Conducted were (1)improvement of a numerical method, (2)survey and examination on constitutive equations for mass transfer terms in annular-mist flow, (3) survey and verification of constitutive equations for momentum transfer terms, (4)collection of experimental database on steam-water and air-water annular-mist flows and numerical analyses of the database to verify the prediction method, (5)extensivc survey on expelimental techniques for annular-mist flow and (6)examination on the governing equations. As a result, the following conclusions were obtained: (a)multi-fluid modeling for all flow regimes were completed, (b)numerical stability of the three-fluid model was darified, (c)stability-enhanced solution method was developed, (d)ill-posedness of the equation system was revealed, (c)a physically-rational and well-posed multi-fluid model was proposed for dispersed flows, (f)systematic survcy and evaluation of constitutive equations for entrainment and deposition were conducted and summarized, (g)a theoretical method for evaluating film thickness, interfacial shear stress and wall shear stress was presented, and (h)it was confirmed that FIDAS-1DS can accurately predict critical heat fluxes under atmosphelic pressure, and that it can givc qualitatively good predictions concerning film thickness, droplet flow rate and so forth of the air-water annular-mist flow.