Tapping the oceans3 April 2002
The prospects of using nuclear energy for seawater desalination on a large scale are attractive since desalination is an energy intensive process. By T Konishi and B M Misra
The successful operation of the sodium-cooled BN-350 fast breeder reactor at Aktau, Kazakhstan, has proved the technical feasibility, compliance with safety requirements and reliability of cogeneration reactors. On a smaller scale, some ten desalination facilities connected to PWRs have been operated successfully in Japan.
Large scale commercial deployment of nuclear desalination will depend on its economic competitiveness with alternate energy supply options, and market demand in countries where water and energy needs are most acute.
The IAEA brought together experts from different countries to study technical, economic and other aspects of nuclear desalination. Activities included preparation and publication of "Options Identification Programme for Demonstration of Nuclear Desalination" (TECDOC-898), and the proceedings of the International Symposium on Nuclear Desalination of Seawater in 1997 (Proceedings Series STI/PUB/1025). The findings added momentum to efforts in many states interested in evaluating, planning or initiating nuclear desalination projects.
All nuclear reactors can provide energy that could be used for desalination. Some relevant experience has come from nuclear plants that are used for district heating systems, a topic which the IAEA has reviewed in a technical document (TECDOC-1056). The safety, regulatory and environmental concerns in nuclear desalination are those related directly to nuclear power plants, with consideration given to the process of coupling the plant to the desalination facility. Existing international safety standards and guides seem to be appropriate in covering such desalination plants.
An IAEA-coordinated research project on "Optimisation of the Coupling of Nuclear Reactors and Desalination Systems" started in 1998 with participation of research institutes from nine countries. The work reviews reactor designs suitable for coupling with desalination systems, the optimisation of this coupling, performance improvements, and advanced technologies of desalination systems for nuclear desalination.
Helpful to many countries has been and IAEA software package called "Desalination Economic Evaluation Program" (DEEP). Its output includes the levelised cost of water and power, a breakdown of cost components, energy consumption and net saleable power of each option. Specific plants can be modelled by adjustment of input data including design power, power cycle parameters and costs.
DEEP serves three objectives. It enables calculation of the levelised cost of electricity and desalted water as a function of quantity, site-specific parameters, energy source and desalination technology. Secondly, it enables side-by-side comparison of a large number of design alternatives on a consistent basis with common assumptions. Thirdly, it enables quick identification of the lowest cost options for providing specified quantities of desalted water and/or power at a given location.
The software has been applied to perform a comprehensive economic assessment of nuclear desalination in comparison with fossil options. The results - published in IAEA TECDOC-1186 - generally show that nuclear desalination can offer potable water at a cost in the same range as fossil options. Hence, both options can be seen as viable in many regions.
A new IAEA publication, "Introduction of Nuclear Desalination: A Guidebook" (Technical Report Series STI/DOC/010/400), gives an overview of nuclear desalination. It also identifies special consideration for decision-making, and provides guidance for steps to be taken on nuclear desalination.
To aid development activities, IAEA has collected and disseminated relevant information at technical meetings attended by experts from states which are operating, designing, planning, or interested in nuclear desalination.
To add to the operating experience in Japan and Kazakhstan, new nuclear desalination plants are foreseen for demonstration in several countries. South Korea has progressed in the design of a cogenerating nuclear desalination plant using a 330MWt reactor called SMART. The Russian Federation has embarked on a nuclear desalination project using a series of barge-mounted units known as KLT-40C. India has become a front-runner in demonstrating nuclear desalination by coupling new desalination facilities to its existing 170MWe PHWRs. The construction work has started at Kalpakkam, south of Chennai.
In 1999, the IAEA launched an interregional technical cooperation project, "Integrated Nuclear Power and Desalination System Design", to provide a forum for technology suppliers and prospective recipients for joint development of integrated nuclear desalination concepts. The aim is to demonstrate the viability of nuclear desalination at specific sites.
Indonesia, Tunisia, Pakistan and Iran have made specific requests for technical assistance under this framework to initiate or plan feasibility studies under specific local conditions. Some other developing countries, with greater energy and water problems, have also indicated strong interests in participating in the project.
Prospective technology suppliers involved in international collaborative efforts include South Korea, the Russian Federation, Argentina, Canada, France and China.
Demonstration projects are being planned and evaluated in several countries, to demonstrate the feasibility of using nuclear energy for desalination applications under specific conditions.
Morocco completed its pre-project study in 1998 jointly with China, using a 10MWt heating reactor that produces 8000m3 per day of potable water by a multi-effect distillation process at an-Tan. Egypt initiated a feasibility study in 1999 of a cogenerating plant for electricity and potable water production at El-Dabaa on the Mediterranean coast.
The Bhabha Atomic Research Centre (BARC) has been engaged in R&D of desalination since the 1970s to augment water sources in areas of scarcity. As a result, multi-stage flash (MSF) and reverse osmosis (RO) technologies were developed indigenously.
To gainfully employ the experience and expertise in various aspects of desalination activity, BARC is seeking to set up a hybrid MSF-RO desalination demonstration plant coupled to the 170MWe PHWR units operating at the Madras Atomic Power Station at Kalpakkam, in southeast India.
The Nuclear Desalination Demonstration Project (NDDP) includes an MSF plant with a capacity of 4500m3 per day and an RO plant having a capacity of 1800m3 per day. Together they would provide enough desalted water to meet the dual needs of process water for the nuclear power plant and of drinking water for the neighbouring people. Objectives of the demonstration plant are:
• To establish the indigenous capability for the design, manufacture, installation and operation of nuclear desalination plants.
• To generate necessary design inputs and optimum process parameters for a large-scale nuclear desalination plant.
• To serve as a demonstration project for interested IAEA Member States.
The project at Kalpakkam started in 1998. The preliminary safety analysis report (PSAR) and preliminary design bases report were prepared. The major equipment is now in various stages of procurement or fabrication. Civil work is in progress and the buildings housing the MSF and RO plants, as well as administration, are near completion. The PSAR has been approved and the final safety analysis report is being prepared.
Most of the equipment will reach the site in 2002. Trial runs and commissioning are envisaged later in 2002. On completion of the commissioning test, the NDDP will be open to international participation under the IAEA umbrella to share relevant information of operation and maintenance of a nuclear desalination plant.
Based on project experience, completion of standardised plants with a capacity of 10 million gallons a day would be completed by the year 2005. The plants would use both the MSF and RO processes and become available for commercial use in the country.
For large-scale deployment of nuclear desalination, one of the most decisive factors is economic competitiveness. Operating experience in Kazakhstan and in Japan may not be a strong indicator of economic viability in many developing countries now considering nuclear desalination.
Strongly needed is the demonstration of economic viability under local conditions in more countries. Successful commissioning and operation of the Kalpakkam plant in India will deepen technical and economic confidence in nuclear desalination. Importantly, the plant's operation and maintenance experience will be shared with other interested countries.
In 2002, the IAEA is planning an international symposium to review the status of nuclear desalination. As experience is gained and shared, countries can assess the role that this multi-faceted nuclear technology can play to meet rising electricity and water needs.