Heat Transfer Engineering , 23:1–2, 2002Copyright C°° 2002 Taylor & Francis0145–7632/02 $12.00 + .00

editor ia lSeawater Desalination Using NuclearEnergy

Worldwide availability of potable water greatly exceedsthe amounts needed and used, but resources are not evenlydistributed. The importance of having adequate supplies ofpotable water for growing populations and complex prob-lems of satisfying this need has been globally recognized.Although about 70% of the planet is covered with water, thereality is that 97.5% of all water on earth is salt water, leavingonly 2.5% as fresh water. Nearly 70% of this fresh water isfrozen in the icecaps of Antarctica and Greenland, and mostof the remainder is present as soil moisture, or lies in deep un-derground aquifers as groundwater not accessible to humanuse. As a result, less than 1% of the world’s freshwater, orabout 0.007% of all the water on earth, is readily accessiblefor direct human use. This is the water found in lakes, rivers,reservoirs, and those underground sources that are shallowenough to be tapped at an affordable cost. Only the amountthat is regularly renewed by rain and snowfall is available ona sustainable basis.

In most cases about 50 L per capita per day is fair enoughfor the people living in peri-urban areas. This should allowfor an acceptable quality of life and human dignity. In someparts of the world, 20 L per capita per day of clean water couldmean a substantial improvement, while elsewhere 200 L percapita per day may be deemed suf� cient. On a global basis,20% of the world’s population lack safe water supplies and50% have no adequate sanitation. Human health is closelylinked to a safe and adequate water supply. The World HealthOrganization (WHO) has calculated that about 5 million peo-ple die each year as a result of unsafe water supplies and badhygienic conditions.

A promising approach for securing abundant fresh wateris seawater desalination. More than two-thirds of the worldsurface is covered with seawater, which thus is abundantlyavailable and relatively unpolluted. In desalting seawater, en-ergy is generally supplied for the desalination process in theform of either steam or electricity. Conventional fossil fuelshave been mostly utilized as energy sources to date for theexisting desalination plants.

However, fossil energy resources are limited and theirincreasingly intensive use raises environmental concerns, in-cluding the threat of a gradual climate change with far-reach-ing consequences. At the same time, worldwide demand forenergy is steadily growing, and adequate solutions are needed.Nuclear energy contributes signi� cantly to the world’s exist-ing supply of energy, and it has the potential to do even more.

Combining the use of nuclear energy with the industrialprocess of supplying potable water by seawater desalinationhas been considered as far back as the 1960s. Indeed, at thattime great optimism prevailed regarding the use of nuclearenergy for seawater desalination as in other forms of heat ap-plications such as district heating. The International AtomicEnergy Agency (IAEA) performed several technical and eco-nomic studies between 1964 and 1967.

The design and construction of the Shevchenko complex(now Aktau in Kazakhstan—see cover photo) was launchedby the former Soviet Union. The BN-350, a liquid metal-cooled fast reactor, went into operation in 1973, and sincethen has provided both electricity and heat for the productionof potable water, producing about 80,000 m3/d of desalinatedwater for municipal use; the reactor is now shut down, butthe desalination facility continues to be in operation by meansof fossil energy. Several nuclear power plants in Japan havebeen desalting a few thousand cubic meters per day eachfor feedwater makeup in the plants as well as for householduse. Operating experience in Japan reaches the order of 100reactor-years.

Any desalination process requires energy, either heat andelectrical energy (mainly for pumping) or electrical energyonly (the use of mechanical energy instead of electrical en-ergy is also possible). The lowest energy consumption in-cluding that for seawater pumps and water pretreatment iscurrently obtained with reverse osmosis (RO) plants. Aftermore than 40 years of intensive research and development inseawater desalination technology, only distillation processesand the RO process have achieved commercial large-scaleapplication.

Energy required for desalination could be provided by nu-clear reactors in the form of heat and/or electricity. A numberof factors are contributing to the promotion of the technologyof nuclear desalination. They include growing concerns aboutthe environmental effects of burning fossil fuels; recognitionof the bene� ts of diversi� cation of energy sources; and thedevelopment of new advanced reactor concepts in the small-and medium-power range.

Regarding nuclear safety, the same principles, criteria, andmeasures would apply as to any nuclear plant. An additionalrequirement is that the product water would have to be ad-equately protected against any conceivable contamination.Experience shows that there are no technical impediments tothe use of nuclear reactors as an energy source for seawaterdesalination. Experience with nuclear desalination exceeds100 reactor-years. Experience with similar heat applicationfor district heating and process heat production reaches theorder of 800 reactor-years and no safety-related incidentshave ever been reported from these plants.

A broad spectrum of nuclear reactors is available today.Worldwide, in 1999 there were 433 nuclear power plants in

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operation with a total installed capacity of 349 GW(e) and37 nuclear power plants under construction. Four new nu-clear power plants were connected to the electricity gridin 1999, and construction started on seven nuclear powerplants.

Some 50 units are providing heat for nonelectrical prod-ucts. They include all principal reactor types, i.e., water-,liquid metal-, and gas-cooled reactors. These technologies,including reactors, which are in an advanced design stage,could be regarded as readily available as energy source forseawater desalination. Most of the new designs under de-velopment are intended to achieve better performance andmeet even stricter safety requirements: passive removal ofdecay heat, simpli� cation of systems, reduction of radioac-tive release even under severe hypothetical conditions, etc. Inprinciple, all nuclear power reactors are capable of providingenergy for desalination processes. Owing to their typicallylow working temperatures, single-purpose heat-only reactorsdesigned for hot water district heating can only be combinedwith distillation processes.

In areas without the possibility of any suitable grid con-nection, the reactors would have to be dedicated exclusivelyto supplying energy to the desalination plant, leading to smallnuclear units. Such small reactors could be installed on shoreas land-based units supplying adjacent desalination plants, oras barge-mounted self-suf� cient � oating plants. This can onlybe analyzed on a case-by-case basis. According to studies,� oating plants using multieffect distillation desalination tech-nology could supply water in the range of about 20,000 m3/dup to 120,000 m3/d. Floating plants using reverse osmosis de-salination technology may reach even 250,000 m3/d. Floatingdesalination plants could be especially attractive for supply-ing temporary demands of potable water.

The studies performed so far have shown that a very largenumber of possible combinations exist among the many dif-ferent reactor concepts, the various desalination processes,and the different coupling schemes.

Apart from nuclear power generation, some developingcountries could also utilize nuclear energy for heat applica-tions. Seawaterdesalination, district heating, and process heatapplication are important areas for many developing coun-tries where nuclear power can play an important role. Theseapplications could be served using small or medium reactors.In addition, some of the developing countries have remote

areas and/or isolated islands where nuclear power could havean advantage over conventional power generation to supplyelectrical power and/or heat for various applications. The totalenergy demand for this application for a given site is usuallyrelatively small [of the order of 100 MW(e)].

Although nuclear energy is not the only means of provid-ing power and process heat, it is a relevant option, especiallyif the environmental issues are to be properly accommodated.In addition, countries that are not blessed with fossil naturalresources could � nd the nuclear option attractive in the longrun. Future nuclear power utilization will likely deploy ad-vanced nuclear power plants that are currently under design.

Activities of the IAEA’s nuclear desalination of seawa-ter have been implemented through international cooperativeefforts with active national participation and related techni-cal and � nancial support. All the results so far illustrate thatthe application of nuclear energy to seawater desalination isa realistic option. The challenge ahead is to demonstrate itsuse by proceeding with effective development and practicalapplications.

The water problem cannot be solved by individual coun-tries, but needs regional or even global approaches. Devel-oping countries are on one hand suffering mostly from watershortages and on the other hand cannot solve these problemsin isolation. International information exchange and coop-eration is needed to address the water problem and identifypossible solutions.

Peter J. GowinVienna, Austria

Contributing Editor

Peter J. Gowin was born in Germany, studied inStuttgart (Germany), Oxford (U.K.), and Vienna(Austria), and holds a Master’s degree in physicsand a Ph.D. in energy economics. He worked foran energy utility as an advisor on utility strate-gies in liberalized energy markets for two years.In 1997 he joined the International AtomicEnergy Agency (IAEA)—a specialized agency inthe United Nations family—where he has beenresponsible for various aspects of the IAEA pro-gram on nuclear desalination. He has presented

several articles on energy and nuclear desalination at the World WaterForum and at the International Desalination Association conferences . Hecan be reached by E-mail: nuclear.desalination@iaea.org .

2 heat transfer engineering vol. 23 no. 1 2002

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