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The role of nuclear desalination in meeting the potable water needs in water scarce areas in the next decades
DESALINATION Desalination 166 (2004) 1-9
ELSEVIER
www.elsevier.con~qocate/desal
The role of nuclear desalination in meeting the potable water needs in water scarce areas in the next decades B.M. Misra*, J. Kupitz lnternational Atomic Energy Agency (IAEA), IOenna,Austria Tel. +43 (1) 2600-22822; Fax +43 (1) 2600 29598; emaih [email protected] Received 16 February 2004; accepted 25 February 2004
Abstract
Recent statistics show that currently 2.3 billion people live in water stressed areas and among them 1.7 billion live in water scarce areas. The situation is going to worsen further in the coming years. Better water conservation, water management, pollution control and water reclamation are all part of the solution to projected water stress. So too are new sources of fresh water, including seawater desalination. Desalination technologies have been now well established and the contracted capacity of the desalination plants worldwide is about 32.4 million m3/d. Interest in nuclear desalination is driven by the expanding global demand for fresh water, by concern about GHG emissions and pollutions from fossil fuels and in developments in small and medium sized reactors that might be more suitable than large power reactors. Among various utilization of nuclear energy for non-electrical products, using it for production of fresh water from seawater (nuclear desalination) has been drawing broad interest in IAEA Member States. IAEA has an active programme for supporting the activities on demonstration of nuclear seawater desalination in the Member States. These include optimisation of the coupling of nuclear reactors with desalination systems, economic research and assessment of nuclear desalination projects, development of software for the economic evaluation of nuclear desalination plants as well as fossil fuel based plants (DEEP). It also provides training to interested Member States in the above areas. It cooperates with various international organizations involved in promoting seawater desalination. The recent developments in nuclear desalination and its future role are discussed in this paper. Keywords: Nuclear desalination; Potable water needs; Water scarce areas; DEEP *Corresponding author. Presented at the EuroMed 2004 conference on Desalination Strategies in South Mediterranean Countries: Cooperation between Mediterranean Countries of Europe and the Southern Rim of the Mediterranean. Sponsored by the European Desalination Society and Office National de l'Eau Potable, Marrakech, Morocco, 30 May-2 June, 2004. 0011-9164/04/$- See front matter © 2004 Elsevier B.V. All rights reserved doi;10.1016/j.desal.2004.06.053
2
B.M. Misra, J. Kupitz/Desalination 166 (2004) 1-9
I. Introduction Nuclear power is a proven technology, which has provided more than 16% of world electricity supply in over 30 countries. More than ten thousand reactor-years of operating experience have been accumulated over the past 5 decades. In recent years, the option of combining nuclear power with seawater desalination has been explored to tackle water shortage problem. The desalination of seawater using nuclear energy is a feasible option to meet the growing demand for potable water. Over 150 reactor-years of operating experience on nuclear desalination have been accumulated worldwide. Several demonstration programs of nuclear desalination are also in progress to confirm its technical and economical viability under country-specific conditions, with technical co-ordination or support of the IAEA [1]. There are many reasons which favour a possible revival of the nuclear power production in the years to come: the development of innovative reactor concepts and fuel cycles with enhanced safety features which are expected to improve public acceptance, the production of less expensive energy as compared to other options, the need for prudent use of fossil energy sources, and the increasing requirements to curtail the production of greenhouse gases (GHG), toxic gases, particulates and acid rain, which are all associated with the combustion of fossil fuels. It is thus expected that this revival would also lead to an increased role of nuclear energy in nonelectrical energy services, which, at the moment, are almost entirely dominated by fossil energy sources. Among various utilization of nuclear energy for non-electrical products, using it for the production of freshwater from seawater (nuclear desalination) has been drawing broad interest in IAEA Member States as a result of acute water shortage issues in many arid and semi-arid zones worldwide. Where nuclear energy could be an option for electricity supply, it can be equally viable as an energy source for seawater desalination. Nuclear
desalination is the production of potable water from seawater in an integrated facility in which a nuclear reactor is used as the source of energy (steam and/or electricity) for the desalination process on the same site. The facility may be dedicated solely to the production of potable water, or may be used for the generation of electricity and the production of potable water, in which case only a portion of the total energy output of the reactor is used for water production. The design approaches for a nuclear desalination plant are essentially derived from those of the nuclear reactor alone, with some additional aspects to be considered in the design of a desalination plant and its integration with the nuclear system. All nuclear reactor types can provide the energy required by the various desalination processes. The amount of energy (heat or electricity) needed for desalination can be readily supplied by tapping the low-grade steam and/or electricity produced by the nuclear plant. In this regard, it has been shown that Small and Medium Reactors (SMRs) offer the big potential as coupling options to nuclear desalination systems.
2. Past experience and current developments Technical feasibility of integrated nuclear desalination had been demonstrated in Kazakhstan and Japan for many years. Their successful operation has proved the technical feasibility, compliance with safety requirements and reliability of cogeneration nuclear reactors. Operating experience exceeds 150 reactor-years as of 2003. The details are given in Table 1 [2]. Table 2 summarizes past experience as well as current developments and plans for nuclearpowered desalination based on various reactor types. Most of the technologies in Table 2 are landbased, but the table also includes a Russian initiative for barge-mounted floating desalination plants. Floating desalination plants could be especially attractive for responding to temporary demands for potable water.
B.M. Misra, J. Kupitz /Desalination 166 (2004) 1-9
Table 1 Experience with nuclear desalination Country
Unit name
Japan
Ikata-1 Ikata-2 Ikata-3 Ohi- 1 Ohi-2 Ohi-3 Ohi-4 Genkai-3 Genkai-4 Takahama-3 Takahama-4 KashiwazakiKariwa 1 Kazakhstan BN-350
Location
Phase
Start of power Power, Water capacity, operation MWe net m~/d
Desal. process
Ehime Ehime Ehime Fukui Fukui Fukui Fukui Saga Saga Fukui Fukui Niigata
Comm. Comm. Comm. Comm. Comm. Comm. Comm. Comm. Comm. Comm. Comm. Comm.
1977 1982 1994 1979 1979 1991 1993 1994 1997 1985 1985 1985
538 538 846 1120 1120 1127 1127 1127 1127 830 830 1067
MSF
Aktau
Comm.
1973
70
2000 2000 6500 MSF+MDE=3900 RO=2600
RO MSF×2 MDE×I RO×2
1000
MED
1000
MED
1000
MSF
120000
MED/MSF
Table 2 Reactor types and desalination processes Reactor type
Location
LMFR PWRs
Kazakhstan(Aktan) MED, MSF Japan (Ohi, Takahama, Ikata, Genkai) MED,MSF, RO
BWR
Rep. of Korea, Argentina, etc. Russia Japan (Kashiwazaki)
MED, RO MED, RO MSF
India (Kalpakkam) Canada Pakistan (KANUPP) China South Africa, France, The Netherlands
MSF/RO RO (preheat) MED MED MED, MSF, RO
PHWR NHR HTGR
The following are additional details on the new developments [3] in the Member States: ° A r g e n t i n a has identified a site for its small reactor (CAREM), which could be used for d e s a l i n a t i o n . D e p e n d i n g on f i n a n c i n g , construction could begin in the near future. • C a n a d a has embarked on a three-year project to validate its innovative reverse osmosis (RO) system design concepts.
Desalination process
•
•
•
Status In service till 1999 In service with operating experience of over 100 reactor-years. Under design Under design (floating unit) Never in service following testing in 1980s, due to alternative freshwater sources; dismantled in 1999. Being connected Under design Under design Under design Under consideration
C h i n a is proceeding with several conceptual
designs o f nuclear desalination for coastal Chinese cities. F r a n c e has begun feasibility and economic studies on nuclear desalination as part of CEA's own innovation programme and as part of a p r o p o s e d j o i n t E u r o p e a n s t u d y (the EURODESAL Project, Ecowater). E g y p t is working on a two-year feasibility
4
B.M. Misra, J. Kupitz/Desalination 166 (2004) 1-9
study for a nuclear co-generation plant (electricity and water) at E1-Dabaa. Based on the results, government approval to proceed towards implementing the project will be sought. India is building a demonstration plant at Kalpakkam using a 6,300 m3/d hybrid desalination system (MSF-RO) connected to an existing PHWR. Civil engineering and electrical work is completed, and India expects to commission the plant in 2004. The Republic of Korea is proceeding with its SMART (System-integrated Modular Advanced Reactor) concept. Work is into the basic design phase. The project is designed to produce 40,000 m3/d of potable water. Morocco, in June 2000, halted a demonstration project at Tan-Tan originally intended to produce 8000 m3/d of potable water using an NHR-10 of Chinese design. Possible next steps are being studied. Pakistan is considering coupling of a MED thermal desalination plant of 4,800 mVd capacity with existing PHWR at KANUPP. Russia is progressing with the design and licensing of a floating co-generation plant, based on a Nuclear Floating Power Unit (NFPU) with KLT-40C reactors, for the Arctic Sea coast area. Manufacturing of major components started in 2000. Tunisia has undertaken several studies to select a suitable desalination process and to identify what process could be coupled to a nuclear reactor. Two possible desalination sites have been identified in the southeast part of the country for further study. USA will include in its Generation IV roadmap initiative a detailed discussion of potential nuclear energy products in recognition of the important role that future nuclear energy systems can play in producing fresh water. Further R&D activities are also underway in Indonesia and Saudi Arabia. In addition, interest has been expressed by Brazil, Iran, Iraq, Italy, Jordan, Lebanon, Libya, Philippines, and
Syria in the potential for nuclear desalination in their countries or regions.
3. New demonstration projects 3.1. Nuclear desalination demonstration project, Kalpakkam [4]
Salient performance of an MSF-RO hybrid desalination system is being demonstrated at the demonstration facility connected to two units of PHWRs at Kalpakkam, India. The hybrid plant has many advantages under the site-specific conditions. The seawater feed for the desalination plant is taken from the outfall of the NPP. The SWRO plant, which is already commissioned, operates at relatively lower pressure (5.1 MPa during the 1st year and 5.4 MPa during the 3rd year) to save energy, employs lesser pretreatment (because of relatively clean feed water from MAPS outflow) and aims for longer membrane life resulting in lower water cost. The MSF plant which is in advanced stage of completion is designed for higher top brine temperature with Oain to Output Ratio (OOR) of 9:1 and utilizes less pumping power (being long tube design)Fig. 1 shows a view of SWRO membrane modules at Kalpakkam. The design parameters and operating data of SWRO plant during the first month of commis-
Fig. 1. Viewof SWROmembranemodules at Kalpakkam.
B.M. Misra, J. Kupitz /Desalination 166 (2004) 1-9 Table 3 Design values and operating data of 1800 m3/d SWRO plant, NDDP Design values Treated water quality NTU <0.5 SDI <3.0 ORP reading <160 mV pH 6.5 Temperature <35 °C RO section parameters Feed TDS 35,600 ppm Recovery 35% Working pressure 5.1 MPa at first year and 5.4 MPa after three years @ 30°C Permeate quality TDS <400 ppm pH -5.5 Product quality (after post-treatment) TDS <500 ppm pH 7.5-8.0 LSI: Slightly positive Energy consumption 6 kWh/m 3
sioning in 2002 are given in Table 3. The plant has now completed one year of successful operation. 3.2. Desalination plant at K A N U P P [5] The multi effect distillation (MED) plant has been selected for coupling with K A N U P E The selection of MED has been made considering the extraction steam conditions to be used as thermal energy for desalination and due to significant advantages o f M E D over the other distillation processes. Main parameters o f the MED plant are given in Table 4.
4. Description of coupling scheme (isolation loop) Considering various options for tapping steam from KANUPP, as a source of heat energy to the proposed desalination plant, it was found that the primary steam bled from high-pressure turbine to
Operating data during 1st one month of commissioning NTU <0.2 SDI <3.0 ORP reading <160 mV pH 6.5 Temperature <35°C Feed TDS 24,000-35,000 ppm Recovery 35% Working pressure 3.8-4.6 MPa @ 28°C
TDS 100-140 ppm pH -5.5 TDS 150-230 ppm pH 7.5-8.0 LS1-0.3 at pH 7.7 -5.0 kWh/m3
Table 4 Characteristics of the thermal desalination plant Parameter Plant capacity, ma/d Type Gain output ratio (GOR) Seawater TDS, mg/1 Steam consumption
4 800 MED, LT-HTME, without TVC t0 42 000 19.4 t/h at 75°C, saturated
the feed water heater (a regenerative heat exchanger) closely matches the requirements, and electrical energy losses are also lower as compared with other options. The bled steam conditions at feed water heater, corresponding to power plant output of 85 MWe, are: T = 113°C, wetness = 25%, P = 1.57 bara, flow= 27700 kg/h. This steam will transfer heat to the pressurized water loop and the condensate will return to the condenser. The secondary steam,
6
B.M. Misra, .1..Kupitz /Desalination 166 (2004) 1-9
Intermediate Isolation Loop /
PRESSURIZER
V f"
STEAM TO MED PLANT P= 0.408 BAR T=77C
STEAM = 27666 KG/HR 25% Wet, T=113C
FEED WATER
UP EVAPORATOR
HEATER (COW-HX3)
CONDENSATE TOCONDENSER T= 87.8 C
Fig. 2. Schematicdiagram of coupling a desalinationplant (MED) with KANUPP.
produced in the evaporator (HX), at a temperature of 77°C. 0.408 bara, will be used in the first effect of the desalination plant and its condensate will return to the evaporator. The schematic diagram of coupling desalination plant with KANUPP is shown in Fig. 2. The existing intake structure of KANUPP will be used to pump raw seawater for the desalination plant. Useful design and operational experience is expected from these two demonstration projects, which can be utilized for introducing large size nuclear desalination plants in future to meet the potable water needs of large population.
5. Future potential Looking to the future, there are two main reasons for focusing now on expanding nuclear power's contribution of both heat and electricity for desalination. One is the expanding demand for freshwater as described above, and the second is the increasing concern about greenhouse gas (GHG) emissions and pollution from fossil fuels. There is also now a growing emphasis on small and medium size reactors, and this may prove important for desalination because the countries most in need of freshwater often have limited
industrial infrastructures and electricity grids. The size of the grid limits the possibilities for integrating a co-generating nuclear power plant into the grid to supply the electricity, in addition to meeting the energy requirements of a desalination plant. The largest power unit that can be integrated into an electricity grid is about 10-20% of the grid capacity. A country's assessment of the advantages and disadvantages of nuclear powered desalination compared to alternatives will also take into account essentially the same issues that are considered when assessing electricity generation options. They include the diversification of energy sources, expected spin-off effects in industrial development, safety, fuel-cycle issues, and the need to build up the necessary nuclear infrastructure - - if it does not already exist - including appropriate training, a legal framework and a regulatory regime. It is expected that reactors for desalination purposes will be designed, constructed and operated in accordance with the latest internationally recognised safety standards for NPPs. The high-temperature gas-cooled reactor (HTGR) design, one of the reactor concepts currently under consideration for future nuclear
B.M. Misra, J. Kupitz /Desalination 166 (2004) 1-9
power plant deployment, is one of the candidate reactor designs well suited for such process heat applications. While traditionally, emphasis has been on HTGR suitability for high-temperature applications such as hydrogen production, with recent advances in gas- turbine designs, HTGRs offer virtually cost-free waste heat at the cycle sink boundary, and interestingly enough, at just the desired range of temperatures (100-120°C) needed for desalination. Since a good portion of the total production cost of seawater desalination, in the range of 30-50%, is attributed to energy cost, the potential exists for a significant reduction in the cost of fresh water production using an HTGR in co-generation mode [6]. 6. IAEA recent activities in nuclear desalination
The IAEA has been providing its Member States with the publication of guidebooks, technical documents, and computer programmes on nuclear desalination as well as the provision of technical assistance through the framework of technical co-operation programmes. The International Nuclear Desalination Advisory Group (INDAG), which was established in 1997, is now in its second term since 2001. At its recent meeting in July 2002, INDAG reviewed the status of ongoing and planned demonstration projects in Member States and advised the IAEA to facilitate further exchange of information and experience from these projects. The IAEA will formulate its programmes in a direction to meet country-specific needs in the frame of technical co-operation programmes and co-ordinated research projects (CRP). A number of technical co-operation projects have assessed the feasibility of particular projects. In 1999 the IAEA launched an interregional technical co-operation project "Integrated Nuclear Power and Desalination System Design". The project is designed to facilitate international collaboration between technology holders and potential end-users for the joint development of
7
integrated nuclear desalination concepts, aiming at the demonstration of the viability of nuclear desalination at a specific site or sites. Under the IAEA regional technical co-operation framework, several international collaboration activities are underway, for example, between the Republic of Korea and Indonesia; and France and Tunisia. Using the Desalination Economic Evaluation Program (DEEP) computer code, the IAEA carried out a series of detailed economic calculations of desalination by a wide range of fossil and nuclear energy sources, coupled to selected desalination technologies. The studies consisted of a set of DEEP calculations for three broad geographical regions. In addition, a sensitivity analysis was carded out to permit the evaluation of desalination options as a function of plausible variations in key parameters such as power level and reactor type. A CRP on "Optimization of the Coupling of Nuclear Reactors and Desalination Systems", which started in 1998, covers a review of reactor designs suitable for coupling with desalination systems, the optimization of this coupling, possible performance improvements and advanced technologies of desalination systems for nuclear desalination. The CRP is identifying optimum coupling conditions for a wide variety of nuclear system and desalination processes. The final research co-ordination meeting was convened in February 2003. A new CRP on "Economic Research on, and Assessment of, Selected Nuclear Desalination Projects and Case Studies" has started early 2002 with the participation of 11 institutions from 11 Member States. It will deepen the economic aspects of nuclear desalination plants and give more confidence in this option. The second research co-ordination meeting was held in October 2003. 7. Economics
Economic comparisons indicate that water costs (and associated electricity generation costs)
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B.M. Misra, d. Kupitz /Desalination 166 (2004) 1-9
from nuclear seawater desalination are generally in the same range as costs associated with fossilfuelled desalination. A detailed economic analysis by the IAEA looks at three representative water shortage regions distinguished by their seawater and economic characteristics relevant to desalination. The three regions are Southern Europe (South of France, Italy, Greece, Turkey and Spain); the North Africa, Red Sea and South East Asian region; and the Arabian Gulf region. Given the conclusion that nuclear and fossil-fuelled desalination are broadly competitive with each other, any particular future investment decision will depend on site-specific cost factors and on the values of key parameters (fuel price, interest rate, construction time, etc.) at the time of investment. Higher fossil fuel prices would of course favour nuclear desalination; higher interest rates would favour less capital-intensive fossil-fuelled options. The broader picture however, is that the worldwide use of desalination is still negligible compared to the demand for fresh water. To become a noticeable (and quantifiable) market for nuclear energy, desalination needs to compete successfully with alternative means of increasing fresh water supply. For nuclear desalination to be attractive in any given country, two factors must be in place simultaneously: a lack of water and the ability to use nuclear energy for desalination. In most regions, only one of the two is present. Both are present for example in China, the Republic of Korea and, even more so, in India and Pakistan. These regions already account for almost half the world's population, and thus represent a potential long-term market for nuclear desalination. There are already plans in these countries to deploy large size nuclear desalination plants in this decade. The market will expand further to the extent that regions with high projected water needs, such as the Middle East and North Africa, increase their nuclear expertise and capabilities. Recent feasibility studies [7] on the economic evaluation of coupling NHR-200 with VTE-MED
process has been carried out in China. The analysis was based on the site-specific case study of Shandong nuclear desalination project, domestic market price in China and innovative technical design. As a result the specific desalted water cost for a 160,000 m3/d plant was estimated to be US$0.61/m 3. Similar economic evaluation [8] of the integrated SMART desalination plant of 40,000 m3/d capacity was carried out using IAEA's DEEP. The water cost ranges from US$0.70/m 3 to US$0.90/m 3. The projected cost of water from Russian KLT-40 floating reactor based nuclear desalination plants is also in the above ranges. These studies indicate the possibility of safe and economic production of potable water from nuclear desalination plants in the future. 8. Conclusion
It is now well recognised that nuclear desalination will be a viable option for sustainable water security in the coming years in many parts of the world suffering from water scarcity/stress. The activities on nuclear desalination in the Member States are now shifting from feasibility studies to setting of experimental facilities and demonstration projects. International collaboration between interested Member States is also taking place in the development of plans for setting up of nuclear power-desalination plants at suitable sites. The experiences gained from these studies will be useful in deployment of large size desalination plants in future for safe and economic production of fresh water using nuclear energy. Economic research aiming towards further water cost reduction is desirable for large-scale adoption of nuclear desalination.
References
[1] P.E. Juhn, IAEA Nuclear seawater desalination activities, International Conference on Nuclear Desalination,Marrakech,October2002. [2] T. Konishi, J. Kupitz and M.M. Megahed,
B.M. Misra, .1. Kupitz / Desalination 166 (2004) 1-9
Optimization of the coupling of nuclear reactors and desalination systems, GENES4, Kyoto, September, 2003. [3] IAEA Nuclear Technology Review 2002. [4] B.M. Misra, Advances in nuclear desalination, Int. J. Nuclear Desalination, 1(1)(2003) 19. [5] M.M. Tariq, Nuclear desalination in Pakistan,
9
INDAG Newsletter # 3, 2003. [6] M. Methanani and J. Kendall, Coupling and thermodynamic aspects of seawater desalination using high temperature gas-cooled reactors, IDA World Congress, Bahamas, September, 2003. [7] S. Wu, INET Progress Report, 2003. [8] Y.D.Hwang et al., KAERI, Progress Report, 2003.
ELSEVIER
www.elsevier.con~qocate/desal
The role of nuclear desalination in meeting the potable water needs in water scarce areas in the next decades B.M. Misra*, J. Kupitz lnternational Atomic Energy Agency (IAEA), IOenna,Austria Tel. +43 (1) 2600-22822; Fax +43 (1) 2600 29598; emaih [email protected] Received 16 February 2004; accepted 25 February 2004
Abstract
Recent statistics show that currently 2.3 billion people live in water stressed areas and among them 1.7 billion live in water scarce areas. The situation is going to worsen further in the coming years. Better water conservation, water management, pollution control and water reclamation are all part of the solution to projected water stress. So too are new sources of fresh water, including seawater desalination. Desalination technologies have been now well established and the contracted capacity of the desalination plants worldwide is about 32.4 million m3/d. Interest in nuclear desalination is driven by the expanding global demand for fresh water, by concern about GHG emissions and pollutions from fossil fuels and in developments in small and medium sized reactors that might be more suitable than large power reactors. Among various utilization of nuclear energy for non-electrical products, using it for production of fresh water from seawater (nuclear desalination) has been drawing broad interest in IAEA Member States. IAEA has an active programme for supporting the activities on demonstration of nuclear seawater desalination in the Member States. These include optimisation of the coupling of nuclear reactors with desalination systems, economic research and assessment of nuclear desalination projects, development of software for the economic evaluation of nuclear desalination plants as well as fossil fuel based plants (DEEP). It also provides training to interested Member States in the above areas. It cooperates with various international organizations involved in promoting seawater desalination. The recent developments in nuclear desalination and its future role are discussed in this paper. Keywords: Nuclear desalination; Potable water needs; Water scarce areas; DEEP *Corresponding author. Presented at the EuroMed 2004 conference on Desalination Strategies in South Mediterranean Countries: Cooperation between Mediterranean Countries of Europe and the Southern Rim of the Mediterranean. Sponsored by the European Desalination Society and Office National de l'Eau Potable, Marrakech, Morocco, 30 May-2 June, 2004. 0011-9164/04/$- See front matter © 2004 Elsevier B.V. All rights reserved doi;10.1016/j.desal.2004.06.053
2
B.M. Misra, J. Kupitz/Desalination 166 (2004) 1-9
I. Introduction Nuclear power is a proven technology, which has provided more than 16% of world electricity supply in over 30 countries. More than ten thousand reactor-years of operating experience have been accumulated over the past 5 decades. In recent years, the option of combining nuclear power with seawater desalination has been explored to tackle water shortage problem. The desalination of seawater using nuclear energy is a feasible option to meet the growing demand for potable water. Over 150 reactor-years of operating experience on nuclear desalination have been accumulated worldwide. Several demonstration programs of nuclear desalination are also in progress to confirm its technical and economical viability under country-specific conditions, with technical co-ordination or support of the IAEA [1]. There are many reasons which favour a possible revival of the nuclear power production in the years to come: the development of innovative reactor concepts and fuel cycles with enhanced safety features which are expected to improve public acceptance, the production of less expensive energy as compared to other options, the need for prudent use of fossil energy sources, and the increasing requirements to curtail the production of greenhouse gases (GHG), toxic gases, particulates and acid rain, which are all associated with the combustion of fossil fuels. It is thus expected that this revival would also lead to an increased role of nuclear energy in nonelectrical energy services, which, at the moment, are almost entirely dominated by fossil energy sources. Among various utilization of nuclear energy for non-electrical products, using it for the production of freshwater from seawater (nuclear desalination) has been drawing broad interest in IAEA Member States as a result of acute water shortage issues in many arid and semi-arid zones worldwide. Where nuclear energy could be an option for electricity supply, it can be equally viable as an energy source for seawater desalination. Nuclear
desalination is the production of potable water from seawater in an integrated facility in which a nuclear reactor is used as the source of energy (steam and/or electricity) for the desalination process on the same site. The facility may be dedicated solely to the production of potable water, or may be used for the generation of electricity and the production of potable water, in which case only a portion of the total energy output of the reactor is used for water production. The design approaches for a nuclear desalination plant are essentially derived from those of the nuclear reactor alone, with some additional aspects to be considered in the design of a desalination plant and its integration with the nuclear system. All nuclear reactor types can provide the energy required by the various desalination processes. The amount of energy (heat or electricity) needed for desalination can be readily supplied by tapping the low-grade steam and/or electricity produced by the nuclear plant. In this regard, it has been shown that Small and Medium Reactors (SMRs) offer the big potential as coupling options to nuclear desalination systems.
2. Past experience and current developments Technical feasibility of integrated nuclear desalination had been demonstrated in Kazakhstan and Japan for many years. Their successful operation has proved the technical feasibility, compliance with safety requirements and reliability of cogeneration nuclear reactors. Operating experience exceeds 150 reactor-years as of 2003. The details are given in Table 1 [2]. Table 2 summarizes past experience as well as current developments and plans for nuclearpowered desalination based on various reactor types. Most of the technologies in Table 2 are landbased, but the table also includes a Russian initiative for barge-mounted floating desalination plants. Floating desalination plants could be especially attractive for responding to temporary demands for potable water.
B.M. Misra, J. Kupitz /Desalination 166 (2004) 1-9
Table 1 Experience with nuclear desalination Country
Unit name
Japan
Ikata-1 Ikata-2 Ikata-3 Ohi- 1 Ohi-2 Ohi-3 Ohi-4 Genkai-3 Genkai-4 Takahama-3 Takahama-4 KashiwazakiKariwa 1 Kazakhstan BN-350
Location
Phase
Start of power Power, Water capacity, operation MWe net m~/d
Desal. process
Ehime Ehime Ehime Fukui Fukui Fukui Fukui Saga Saga Fukui Fukui Niigata
Comm. Comm. Comm. Comm. Comm. Comm. Comm. Comm. Comm. Comm. Comm. Comm.
1977 1982 1994 1979 1979 1991 1993 1994 1997 1985 1985 1985
538 538 846 1120 1120 1127 1127 1127 1127 830 830 1067
MSF
Aktau
Comm.
1973
70
2000 2000 6500 MSF+MDE=3900 RO=2600
RO MSF×2 MDE×I RO×2
1000
MED
1000
MED
1000
MSF
120000
MED/MSF
Table 2 Reactor types and desalination processes Reactor type
Location
LMFR PWRs
Kazakhstan(Aktan) MED, MSF Japan (Ohi, Takahama, Ikata, Genkai) MED,MSF, RO
BWR
Rep. of Korea, Argentina, etc. Russia Japan (Kashiwazaki)
MED, RO MED, RO MSF
India (Kalpakkam) Canada Pakistan (KANUPP) China South Africa, France, The Netherlands
MSF/RO RO (preheat) MED MED MED, MSF, RO
PHWR NHR HTGR
The following are additional details on the new developments [3] in the Member States: ° A r g e n t i n a has identified a site for its small reactor (CAREM), which could be used for d e s a l i n a t i o n . D e p e n d i n g on f i n a n c i n g , construction could begin in the near future. • C a n a d a has embarked on a three-year project to validate its innovative reverse osmosis (RO) system design concepts.
Desalination process
•
•
•
Status In service till 1999 In service with operating experience of over 100 reactor-years. Under design Under design (floating unit) Never in service following testing in 1980s, due to alternative freshwater sources; dismantled in 1999. Being connected Under design Under design Under design Under consideration
C h i n a is proceeding with several conceptual
designs o f nuclear desalination for coastal Chinese cities. F r a n c e has begun feasibility and economic studies on nuclear desalination as part of CEA's own innovation programme and as part of a p r o p o s e d j o i n t E u r o p e a n s t u d y (the EURODESAL Project, Ecowater). E g y p t is working on a two-year feasibility
4
B.M. Misra, J. Kupitz/Desalination 166 (2004) 1-9
study for a nuclear co-generation plant (electricity and water) at E1-Dabaa. Based on the results, government approval to proceed towards implementing the project will be sought. India is building a demonstration plant at Kalpakkam using a 6,300 m3/d hybrid desalination system (MSF-RO) connected to an existing PHWR. Civil engineering and electrical work is completed, and India expects to commission the plant in 2004. The Republic of Korea is proceeding with its SMART (System-integrated Modular Advanced Reactor) concept. Work is into the basic design phase. The project is designed to produce 40,000 m3/d of potable water. Morocco, in June 2000, halted a demonstration project at Tan-Tan originally intended to produce 8000 m3/d of potable water using an NHR-10 of Chinese design. Possible next steps are being studied. Pakistan is considering coupling of a MED thermal desalination plant of 4,800 mVd capacity with existing PHWR at KANUPP. Russia is progressing with the design and licensing of a floating co-generation plant, based on a Nuclear Floating Power Unit (NFPU) with KLT-40C reactors, for the Arctic Sea coast area. Manufacturing of major components started in 2000. Tunisia has undertaken several studies to select a suitable desalination process and to identify what process could be coupled to a nuclear reactor. Two possible desalination sites have been identified in the southeast part of the country for further study. USA will include in its Generation IV roadmap initiative a detailed discussion of potential nuclear energy products in recognition of the important role that future nuclear energy systems can play in producing fresh water. Further R&D activities are also underway in Indonesia and Saudi Arabia. In addition, interest has been expressed by Brazil, Iran, Iraq, Italy, Jordan, Lebanon, Libya, Philippines, and
Syria in the potential for nuclear desalination in their countries or regions.
3. New demonstration projects 3.1. Nuclear desalination demonstration project, Kalpakkam [4]
Salient performance of an MSF-RO hybrid desalination system is being demonstrated at the demonstration facility connected to two units of PHWRs at Kalpakkam, India. The hybrid plant has many advantages under the site-specific conditions. The seawater feed for the desalination plant is taken from the outfall of the NPP. The SWRO plant, which is already commissioned, operates at relatively lower pressure (5.1 MPa during the 1st year and 5.4 MPa during the 3rd year) to save energy, employs lesser pretreatment (because of relatively clean feed water from MAPS outflow) and aims for longer membrane life resulting in lower water cost. The MSF plant which is in advanced stage of completion is designed for higher top brine temperature with Oain to Output Ratio (OOR) of 9:1 and utilizes less pumping power (being long tube design)Fig. 1 shows a view of SWRO membrane modules at Kalpakkam. The design parameters and operating data of SWRO plant during the first month of commis-
Fig. 1. Viewof SWROmembranemodules at Kalpakkam.
B.M. Misra, J. Kupitz /Desalination 166 (2004) 1-9 Table 3 Design values and operating data of 1800 m3/d SWRO plant, NDDP Design values Treated water quality NTU <0.5 SDI <3.0 ORP reading <160 mV pH 6.5 Temperature <35 °C RO section parameters Feed TDS 35,600 ppm Recovery 35% Working pressure 5.1 MPa at first year and 5.4 MPa after three years @ 30°C Permeate quality TDS <400 ppm pH -5.5 Product quality (after post-treatment) TDS <500 ppm pH 7.5-8.0 LSI: Slightly positive Energy consumption 6 kWh/m 3
sioning in 2002 are given in Table 3. The plant has now completed one year of successful operation. 3.2. Desalination plant at K A N U P P [5] The multi effect distillation (MED) plant has been selected for coupling with K A N U P E The selection of MED has been made considering the extraction steam conditions to be used as thermal energy for desalination and due to significant advantages o f M E D over the other distillation processes. Main parameters o f the MED plant are given in Table 4.
4. Description of coupling scheme (isolation loop) Considering various options for tapping steam from KANUPP, as a source of heat energy to the proposed desalination plant, it was found that the primary steam bled from high-pressure turbine to
Operating data during 1st one month of commissioning NTU <0.2 SDI <3.0 ORP reading <160 mV pH 6.5 Temperature <35°C Feed TDS 24,000-35,000 ppm Recovery 35% Working pressure 3.8-4.6 MPa @ 28°C
TDS 100-140 ppm pH -5.5 TDS 150-230 ppm pH 7.5-8.0 LS1-0.3 at pH 7.7 -5.0 kWh/m3
Table 4 Characteristics of the thermal desalination plant Parameter Plant capacity, ma/d Type Gain output ratio (GOR) Seawater TDS, mg/1 Steam consumption
4 800 MED, LT-HTME, without TVC t0 42 000 19.4 t/h at 75°C, saturated
the feed water heater (a regenerative heat exchanger) closely matches the requirements, and electrical energy losses are also lower as compared with other options. The bled steam conditions at feed water heater, corresponding to power plant output of 85 MWe, are: T = 113°C, wetness = 25%, P = 1.57 bara, flow= 27700 kg/h. This steam will transfer heat to the pressurized water loop and the condensate will return to the condenser. The secondary steam,
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Intermediate Isolation Loop /
PRESSURIZER
V f"
STEAM TO MED PLANT P= 0.408 BAR T=77C
STEAM = 27666 KG/HR 25% Wet, T=113C
FEED WATER
UP EVAPORATOR
HEATER (COW-HX3)
CONDENSATE TOCONDENSER T= 87.8 C
Fig. 2. Schematicdiagram of coupling a desalinationplant (MED) with KANUPP.
produced in the evaporator (HX), at a temperature of 77°C. 0.408 bara, will be used in the first effect of the desalination plant and its condensate will return to the evaporator. The schematic diagram of coupling desalination plant with KANUPP is shown in Fig. 2. The existing intake structure of KANUPP will be used to pump raw seawater for the desalination plant. Useful design and operational experience is expected from these two demonstration projects, which can be utilized for introducing large size nuclear desalination plants in future to meet the potable water needs of large population.
5. Future potential Looking to the future, there are two main reasons for focusing now on expanding nuclear power's contribution of both heat and electricity for desalination. One is the expanding demand for freshwater as described above, and the second is the increasing concern about greenhouse gas (GHG) emissions and pollution from fossil fuels. There is also now a growing emphasis on small and medium size reactors, and this may prove important for desalination because the countries most in need of freshwater often have limited
industrial infrastructures and electricity grids. The size of the grid limits the possibilities for integrating a co-generating nuclear power plant into the grid to supply the electricity, in addition to meeting the energy requirements of a desalination plant. The largest power unit that can be integrated into an electricity grid is about 10-20% of the grid capacity. A country's assessment of the advantages and disadvantages of nuclear powered desalination compared to alternatives will also take into account essentially the same issues that are considered when assessing electricity generation options. They include the diversification of energy sources, expected spin-off effects in industrial development, safety, fuel-cycle issues, and the need to build up the necessary nuclear infrastructure - - if it does not already exist - including appropriate training, a legal framework and a regulatory regime. It is expected that reactors for desalination purposes will be designed, constructed and operated in accordance with the latest internationally recognised safety standards for NPPs. The high-temperature gas-cooled reactor (HTGR) design, one of the reactor concepts currently under consideration for future nuclear
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power plant deployment, is one of the candidate reactor designs well suited for such process heat applications. While traditionally, emphasis has been on HTGR suitability for high-temperature applications such as hydrogen production, with recent advances in gas- turbine designs, HTGRs offer virtually cost-free waste heat at the cycle sink boundary, and interestingly enough, at just the desired range of temperatures (100-120°C) needed for desalination. Since a good portion of the total production cost of seawater desalination, in the range of 30-50%, is attributed to energy cost, the potential exists for a significant reduction in the cost of fresh water production using an HTGR in co-generation mode [6]. 6. IAEA recent activities in nuclear desalination
The IAEA has been providing its Member States with the publication of guidebooks, technical documents, and computer programmes on nuclear desalination as well as the provision of technical assistance through the framework of technical co-operation programmes. The International Nuclear Desalination Advisory Group (INDAG), which was established in 1997, is now in its second term since 2001. At its recent meeting in July 2002, INDAG reviewed the status of ongoing and planned demonstration projects in Member States and advised the IAEA to facilitate further exchange of information and experience from these projects. The IAEA will formulate its programmes in a direction to meet country-specific needs in the frame of technical co-operation programmes and co-ordinated research projects (CRP). A number of technical co-operation projects have assessed the feasibility of particular projects. In 1999 the IAEA launched an interregional technical co-operation project "Integrated Nuclear Power and Desalination System Design". The project is designed to facilitate international collaboration between technology holders and potential end-users for the joint development of
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integrated nuclear desalination concepts, aiming at the demonstration of the viability of nuclear desalination at a specific site or sites. Under the IAEA regional technical co-operation framework, several international collaboration activities are underway, for example, between the Republic of Korea and Indonesia; and France and Tunisia. Using the Desalination Economic Evaluation Program (DEEP) computer code, the IAEA carried out a series of detailed economic calculations of desalination by a wide range of fossil and nuclear energy sources, coupled to selected desalination technologies. The studies consisted of a set of DEEP calculations for three broad geographical regions. In addition, a sensitivity analysis was carded out to permit the evaluation of desalination options as a function of plausible variations in key parameters such as power level and reactor type. A CRP on "Optimization of the Coupling of Nuclear Reactors and Desalination Systems", which started in 1998, covers a review of reactor designs suitable for coupling with desalination systems, the optimization of this coupling, possible performance improvements and advanced technologies of desalination systems for nuclear desalination. The CRP is identifying optimum coupling conditions for a wide variety of nuclear system and desalination processes. The final research co-ordination meeting was convened in February 2003. A new CRP on "Economic Research on, and Assessment of, Selected Nuclear Desalination Projects and Case Studies" has started early 2002 with the participation of 11 institutions from 11 Member States. It will deepen the economic aspects of nuclear desalination plants and give more confidence in this option. The second research co-ordination meeting was held in October 2003. 7. Economics
Economic comparisons indicate that water costs (and associated electricity generation costs)
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from nuclear seawater desalination are generally in the same range as costs associated with fossilfuelled desalination. A detailed economic analysis by the IAEA looks at three representative water shortage regions distinguished by their seawater and economic characteristics relevant to desalination. The three regions are Southern Europe (South of France, Italy, Greece, Turkey and Spain); the North Africa, Red Sea and South East Asian region; and the Arabian Gulf region. Given the conclusion that nuclear and fossil-fuelled desalination are broadly competitive with each other, any particular future investment decision will depend on site-specific cost factors and on the values of key parameters (fuel price, interest rate, construction time, etc.) at the time of investment. Higher fossil fuel prices would of course favour nuclear desalination; higher interest rates would favour less capital-intensive fossil-fuelled options. The broader picture however, is that the worldwide use of desalination is still negligible compared to the demand for fresh water. To become a noticeable (and quantifiable) market for nuclear energy, desalination needs to compete successfully with alternative means of increasing fresh water supply. For nuclear desalination to be attractive in any given country, two factors must be in place simultaneously: a lack of water and the ability to use nuclear energy for desalination. In most regions, only one of the two is present. Both are present for example in China, the Republic of Korea and, even more so, in India and Pakistan. These regions already account for almost half the world's population, and thus represent a potential long-term market for nuclear desalination. There are already plans in these countries to deploy large size nuclear desalination plants in this decade. The market will expand further to the extent that regions with high projected water needs, such as the Middle East and North Africa, increase their nuclear expertise and capabilities. Recent feasibility studies [7] on the economic evaluation of coupling NHR-200 with VTE-MED
process has been carried out in China. The analysis was based on the site-specific case study of Shandong nuclear desalination project, domestic market price in China and innovative technical design. As a result the specific desalted water cost for a 160,000 m3/d plant was estimated to be US$0.61/m 3. Similar economic evaluation [8] of the integrated SMART desalination plant of 40,000 m3/d capacity was carried out using IAEA's DEEP. The water cost ranges from US$0.70/m 3 to US$0.90/m 3. The projected cost of water from Russian KLT-40 floating reactor based nuclear desalination plants is also in the above ranges. These studies indicate the possibility of safe and economic production of potable water from nuclear desalination plants in the future. 8. Conclusion
It is now well recognised that nuclear desalination will be a viable option for sustainable water security in the coming years in many parts of the world suffering from water scarcity/stress. The activities on nuclear desalination in the Member States are now shifting from feasibility studies to setting of experimental facilities and demonstration projects. International collaboration between interested Member States is also taking place in the development of plans for setting up of nuclear power-desalination plants at suitable sites. The experiences gained from these studies will be useful in deployment of large size desalination plants in future for safe and economic production of fresh water using nuclear energy. Economic research aiming towards further water cost reduction is desirable for large-scale adoption of nuclear desalination.
References
[1] P.E. Juhn, IAEA Nuclear seawater desalination activities, International Conference on Nuclear Desalination,Marrakech,October2002. [2] T. Konishi, J. Kupitz and M.M. Megahed,
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Optimization of the coupling of nuclear reactors and desalination systems, GENES4, Kyoto, September, 2003. [3] IAEA Nuclear Technology Review 2002. [4] B.M. Misra, Advances in nuclear desalination, Int. J. Nuclear Desalination, 1(1)(2003) 19. [5] M.M. Tariq, Nuclear desalination in Pakistan,
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INDAG Newsletter # 3, 2003. [6] M. Methanani and J. Kendall, Coupling and thermodynamic aspects of seawater desalination using high temperature gas-cooled reactors, IDA World Congress, Bahamas, September, 2003. [7] S. Wu, INET Progress Report, 2003. [8] Y.D.Hwang et al., KAERI, Progress Report, 2003.