Desalination, 235 (2009), 9-32.

This work was carried out under the specific collaboration agreement between the Bhabha Atomic Research Centre (BARC) from India and the Commissariat à l’Energie Atomique (CEA) from France. This paper summarises first results of review and research on the possible extraction of uranium from the concentrated brine rejected by integrated nuclear desalination systems, which both partners are currently developing in the two organisations. Three innovative and efficient methods of uranium extraction have been proposed: 1) Resin grafted with calixarene: this method has the advantage of very high selectivity. Its performances, especially for large-scale extraction, still need further R&D and optimisation; 2) Magnetic separations: yet another method with high selectivity, easy separation and affording high degree of material recovery. The method, however, is in developmental stage; 3) Canal system with Braid adsorbents: high selectivity. Appears to be feasible in conjunction with existing technology. It would nonetheless require large amounts of adsorbents and adequate infrastructure.

Desalination, 229 (2008), 125-146.

Seawater desalination is now widely accepted as an attractive alternative source of freshwater for domestic and industrial uses. Despite the considerable progress made in the relevant technologies desalination, however, remains an energy intensive process in which the energy cost is the paramount factor. This study is a first of a kind in that we have integrated the environmental costs into the power and desalination costs. The study has focused on the seawater desalination cost evaluation of the following systems. It is supposed that they will be operating in the co-generation mode (simultaneous production of electrical power and desalted water) in 2015: Fossil fuelled based systems such as the coal and oil fired plants and the gas turbine combined cycle plant, coupled to MED, and RO; Pressurised water reactors such as the PWR-900 and the AP-600, coupled to MED, and RO; High temperature reactors such as the GT-MHR, the PBMR, coupled to MED, with the utilisation of virtually free waste-heat provided by these reactors. The study is made in real site-specific conditions of a site in Southern Europe. Sensitivity studies for different parameters such as the fossil fuel prices, interest and discount rates, power costs etc., have also been undertaken. The results obtained are then used to evaluate the financial interest of selected integrated desalination systems in terms of a detailed cash flow analysis, providing the net present values, pay back periods and the internal rate of returns. Analysis of the results shows that among the fossil fuelled systems the power and desalination costs by circulating fluidized bed coal fired plant would be the lowest with current coal prices. Those by oil fired plants would be highest. In all cases, integrated nuclear energy systems would lead to considerably lower power and water costs than the corresponding coal based systems. When external costs for different energies are internalised in power and water costs, the relative cost differences are considerably increased in favour of the nuclear systems. Financial analysis further confirms these conclusions.

Desalination, 205 (2007), 254-268.

The gas turbine–modular helium cooled reactor (GT–MHR) is currently being developed by an international consortium; the pebble bed modular reactor (PBMR) is to be constructed in South Africa. In both these reactors, circulating helium that has to be compressed in two successive stages cools the reactor core. For thermodynamic reasons, these compression stages require pre-cooling of the helium to about 26°C through the use of pre-cooler and intercooler helium-water heat exchangers. Considerable thermal power (≈300 MWth) is thus dissipated in the precooler and the intercooler. This thermal power is then evacuated to the heat sink. Depending upon the specific designs, the temperature ranges of the water in these exchangers could be between 80 and 130°C. This is an ideal range for desalination in a multiple-effect distillation (MED) plant, which can be coupled between a mixer (of the flows from the pre-cooler and the intercooler) and the switch- cooling unit, evacuating the heat to the heat sink (sea or river). It is thus interesting to evaluate the desalination costs of such a system, utilising virtually free heat. The usual code for desalination cost evaluation is the DEEP software, developed by the International Atomic Energy Agency. Actual versions of DEEP do not have models for GT–MHR and the PBMR providing heat for desalination. This paper describes the successive steps that led CEA to the development of these models from basic thermodynamic considerations and their integration in the new, CEA version of the DEEP code. The models are then applied to a realistic case study based on the TUNDESAL project [1]. It is shown that the desalination cost of a GT–MHR + MED system is 34% lower than that of a gas turbine, combined cycle plant + MED system, for a fossil fuel price of about 21 $/bbl and a discount rate of 8%. Under the same conditions, this cost is 2% lower for the PBMR + MED systems.

Desalination, 205 (2007), 317-331.

This paper focuses on a case study of financing a project of an integrated nuclear desalination system at la Skhira site in Tunisia. More specifically, it shows the financial characteristics of this project, known as TUNDESAL, the main financing mechanisms that can be used, and the principal actions required to attract the potential investors and lenders. The paper describes the basic requirements for the deployment of nuclear energy in a developing or an emerging country, with no previous experience of nuclear power; the specific financial considerations corresponding to the particular characteristics of nuclear desalination projects: high capital costs, high level of risks and uncertainties related in particular to long construction lead times and social and environmental concerns; the main risks of these projects; the profitability study of the TUNDESAL project: application of the discounted cash flow analysis; the main financing sources for the project; the financing schemes that can be used for project implementation and comparison between these schemes in terms of benefits generated, after covering project costs and repayment of lenders and investors; the main actions to be done for making the project financially attractive in order to gain the confidence of investors and international financial institutions (optimal allocation of project risks and uncertainties, a suitable and flexible energy and water tariffs policy, etc.). The analysis has shown that in particular conditions of Tunisia, the most attractive financial scheme could be the “project financing + leasing”.

Desalination, 182 (2005), 449-460

Seawater usually contains sixty elements from the Periodic Table. The brine, rejected by a desalination unit, is a concentrate of all compounds contained by seawater. However, some of the elements are very scarce on land and/or are very expensive. There is thus a strong motivation for extracting these materials. Current practice in countries using large-scale desalination is to reject brine back to the sea. Increasing ecological objections are now being voiced since this rejection leads to a degradation of local fauna and flora. Extraction of materials and subsequent brine conditioning for surface storage would therefore be also another advantage for these integrated desalination plants, making them more environmentally friendly. This paper summarizes our preliminary investigations to achieve the above objectives. Elements of interest were first selected on the basis of several economic, physical-chemical and technical criteria. Research was then undertaken to elaborate a common extraction method. After several different solutions, the protocol finally retained comprises a first extraction of Phosphorus through purification by alum. The next step is the recovery of Caesium through an innovative liquid–liquid extraction approach, based on the use of Calixarenes. Indium is then recovered by another liquid–liquid extraction with the help of organic acids. In the final phase germanium and magnesium are extracted. The remaining solution is principally composed of sodium and potassium chlorides, which are separated by hot lixiviation techniques, using the different solubilities of NaCl and KCl. The protocol of extraction thus elaborated would now require exhaustive economic evaluation and experimental verification. These are currently in progress.

Desalination, 182 (2005), 229-237.

This paper describes a computer package (SIMED) that we have developed to simulate the dynamics of different Multi-Effect Evaporators systems. SIMED is intended to serve as an educational tool to study in particular the MED coupling to nuclear reactors such as GT-MHR, PBMR (high temperature reactors), PWRs, or to fossile energy sources such as the gas turbine combined cycle or the simple oil or gas burners. It is designed to improve the understanding of the MED process, develop a control strategy for plant dynamics and optimise process operating conditions. SIMED supports mainly two flow configurations—depending on the seawater feed system architecture: (1) typical MED, in which sea water is preheated in the final condenser then fed to all effect in parallel. (2) MED with sea water preheat in the final condenser (and other MED effects) then fed to first effect. For each configuration the heat source could be either hot water, provided by an intermediate loop, interface between the nuclear reactor and the desalination process, or the steam, provided by a flash tank, a device used to produce steam trough the depressurisation of hot water based on an intermediate loop. SIMED runs under the Windows 9x/2000/XP operating system. It offers a user–friendly graphical user interface consisting of two modules; the Simulation Wizard and the Post Processor. Simulation Wizard’s role is to guide the user through the steps required to create data files for simulation. These steps include the choice of system architecture, components characteristics, scenarios, and calculation options. Processor is built around tools for the display of simulation resystem flow sheets, variation of important parameters etc. The physical models of SIMED derive from basic mass, energy and momentum conservation equations and supplementary correlation for heat transfer and physical properties. Conservation laws are applied separately to fluid phases (brine pool, vapour space) in system components such as MED effects, condensers, coolers, pumps and ducts. A mathematical model of the whole process is generated automatically depending on user choices concerning system architecture. The models, and the results of their application, in particular to a PWR+MED system, show very promising results.

Desalination, 182 (2005), 483-495.

This paper summarises our investigations on the conceptual studies of the Reverse Osmosis (RO) process with preheating of the feed-water, which is expected to lead to lower specific power consumption and higher water production, thus further reducing the cost of desalination by this advanced RO process.

There are, however, no adequate calculation methods to take into account the effect of temperature on the RO system performance parameters such as the recovery ratio, feed pressure, feed flow and the permeate salinity.

The work presented here tries to fulfil this need through the elaboration of mathematical correlations expressing the variation of these parameters as functions of the input parameters such as feed temperature, feed salinity, and the desired production capacity.

The principle of the method used is to first dimension the RO system with the help of the software ROSA and the membrane SW30 HR380 for a series of calculations (504 cases) giving the variation of the above performance parameters for a large range of the input conditions.

Numerical methods were then used to obtain the correlations giving the complete variation of the performance parameters as functions of the input parameters.

The correlations were then integrated into the desalination cost evaluation code, DEEP, developed by IAEA and in the course of continued development at CEA.

The revised version of the code was then applied to a specific project of nuclear desalination (the TUNDESAL project), currently being carried out in the context of a collaboration agreement between France and Tunisia, under the aegis of the IAEA regional cooperation programme.

Nuclear Engineering & Design, 221 (2003), 251-275.

This paper summarises our recent investigations undertaken as part of the EURODESAL project on nuclear desalination, currently being carried out by a consortium of four European, and one Canadian, industrials and two leading EU R&D organisations.

Major achievements of the project, as discussed in this paper are:

• Coherent demonstration of the technical feasibility of nuclear desalination through the elaboration of coupling schemes for optimum cogeneration of electricity and water and by exploring the unique capabilities of the innovative nuclear reactors and desalination technologies.
• Verification that the integrated system design does not adversely affect nuclear reactor safety.
• Development of codes and methods for an objective economic assessment of the competitiveness and sustainability of proposed options through comparison, in European conditions, with fossil energy based systems.

Results obtained so far seem to be quite encouraging as regards the economical viability of nuclear desalination options.

Thus, for example, specific desalination costs ($/m3 of desalted water) for nuclear systems, such as the AP-600 and the French PWR-900 (reference base case), coupled to multiple effect distillation (MED) or the reverse osmosis (RO) processes, are 30–60% lower than the desalination costs for fossil energy based systems, using pulverised coal and natural gas with combined cycle, at low discount rates and recommended fossil fuel prices. Even in the most unfavourable scenarios for nuclear energy (discount rate=10%, low fossil fuel costs) desalination costs with the nuclear reactors are 7–20% lower, depending upon the desalination capacities. Furthermore, with the advanced coupling schemes, utilising waste heat from nuclear reactors, the gains in specific desalination costs of nuclear systems are increased by another 2–15%, even without system and design optimisation. A preliminary evaluation shows that desalination costs with the GT-MHR, coupled to a MED process, could still be much lower than the above nuclear options for desalting capacities=43 000 m3 per day. This is because its design intrinsically provides “virtually free” heat at ideal temperatures for desalination (80–100°C).