600, 1000 MWe are added to the comparison. Figure (5) illu- strates electricity cost comparison for different energy sources.
Fig. 1. Water cost for three water cooled NPP and 600 MWe
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System Simulation for Coupling Nuclear Power
Plants and Desalination in Different Scenarios
Azza Medhat Elaskary
Abstract— Nuclear power plants generate low carbon electricity, but also a lot of waste heat. That is what makes them particularly suitable for co-location with desalination plants. Analysis of coupling nuclear power with desalination plants is a mandatory prerequisite for such project establishment. This paper describes detailed analyses of power and water costs for several nuclear reactors operating in a cogeneration mode (e.g. PWR, the PHWR, the BWR, high temperature reactors, such as the gas cooled GT-MHR and the small modular reactor SMR). NPP’s are coupled to three main desalination processes, multiple effect distillation (MED), (MSF), reverse osmosis (RO) and two scenarios for hybrid plants (MED+RO, MSF+RO). Comparisons are verified for desalination costs from the cheapest of conventional energy based systems, the 600 MW(e) gas turbine and combined cycle plant (CC-600) to the nuclear energy in various analysis settings for selected site specific conditions. System simulations are performed using IAEA- Desalination Thermodynamic Optimization Program (DE-TOP) and DEEP-4 software. Results have been tabulated or plotted for facilitate taking decisions.
Index Terms— Cost Evaluation, Desalination, Fourth Generation, Modeling RO, MSF, MED, NPPs Simulation.
—————————— ——————————
ENERATION IV nuclear energy roadmap recognized the important role that future nuclear energy systems must play in producing fresh water. In nuclear cogeneration
plants, the primary product has usually been electricity pro- duction, but some of the generated energy can additionally drive a desalination unit for producing fresh water from sea as a byproduct. Coupling of Nuclear Power Plants (NPP) with commercially large desalination plants is mainly classified into two different groups, based on the kind of supplied energy [1]: a. Electrical energy for Reverse Osmosis (RO) and Vapor Compression (VC) processes.
b. Heat energy for distillation processes; Multi-Stage Flash
(MSF) and Multiple-Effect Distillation (MED).
Plans development for setting up of nuclear power-
desalination plants at suitable sites, study the common diffi-
culties in carrying out economic evaluations. Comparisons
should be made between the economics of nuclear power and
fossil power to guide the selection of a set of economic para-
meters for a “fair” comparison. As a matter of fact nuclear
power plants have high capital cost, relatively long construc-
tion times, and relatively low fuel cycle costs whereas fossil
fuelled power plants typically have low capital cost, shorter
construction times and higher fuel cycle costs. The specific
values of these competing factors may change the results to-
wards one of these power options. Also complex calculations
must be made to determine the power and water production
costs resulting from each technical combination in order to
fine-tune the economical optimization for cogeneration plants.
Advanced modeling and simulation are adopted to provide
great opportunities for responsible development of future nuc-
————————————————
• Azza Medhat Elaskary Ph.D. in communications and Electrical Engineer- ing- Alexandria University. Currently is pursuing Post-Doctoral research work at engineering Department, National Center for Radiation Research and Technology, Atomic Energy Authority, Cairo, Egypt.
E-mail:azzaelaskary@yahoo.com
lear energy systems. Benefits of modeling and simulation of nuclear reprocessing systems can be motivated by the ex- pected potential in cost and design margines reduction and development of chemical and thermodynamic processes, also providing accurate prediction for interactions to reduce risk. As a concrete step towards pre-evaluation for Nuclear power plant project the IAEA recently released the Desalination Thermodynamic Optimization Program (DE-TOP). This soft- ware is excel based tool that models generic water cooled reac- tors coupled with seawater desalination plants to compares their performance for different configurations [2] which can be used with the IAEA DEEP software. System simulation presents the three interconnected systems: NPP conversion cycle for the steam power generation, coupling system (inter- mediate isolating loop IIL) and thermal seawater desalination plant. This paper aims to present comprehensively a detailed key factors which controlling the steady state behavior for different coupling options and have been considered for DE- TOP and DEEP4 for plants evaluation and economic analysis. The paper is organized as follows, section II is a models speci- fication, section III is DEEP results tabulation and drawing, section IV is a major factors evaluation, section V is a results analysis, and section VI is the conclusion.
For each geographical area its own characteristics which main- ly control the water and power plant choice, such as cooling water specifications and human resources specifications [3]. In this analysis the results which have been obtained dedicated for a specific site in a North Africa south region, the range of sea temperature and salinity also personal cost are presented. Table 1 illustrates the differences between input data for three specific geographic areas.
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TABLE 1
Geographical Areas Specifications
This reactor has been tested when it is coupled in three desali- nation processes: MED, MSF, RO, hybrid (MED + RO and MSF
+ RO) in a 1: 1 ratio process.
TABLE 3
Results of DEEP calculations for PWR interest rate 5% with
intermediate loop
Site specific data, such as cooling water temperature, is also modeled as a necessary input to show the impact of ambient temperature to the performance of the dual purpose plant. In dual-purpose water and power plants, steam has to be ex- tracted from the power plant to deliver heat for the desalina- tion process [4].
Detailed thermodynamic model for coupled system is of the
main importance when assessing nuclear desalination. In this
analysis DE-TOP has been used for primary energy investiga-
tions for all water cooled nuclear power plants also for steam
and condensed temperature adjustments. Nuclear power plant
model and coupling arrangements are simulated for various
types of reactors, main input parameters are introduced to the
software such as thermal capacity, live steam conditions, re-
heat pressure ratio, feedwater preheating conditions, isentrop-
ic efficiencies, etc [5]. DE-TOP results are summarized in Ta-
ble 2. Table 2 connection scenarios are used for DEEP system
simulation.
Boiling water reactor (BWR) is a type of light water nuclear reactor used for electrical power generation.
TABLE 4
Results of DEEP calculations for BWR interest rate 5% with
intermediate loop
TABLE 2
Typical Steam Production by Different Reactor Types
Coupling configuration models have been built in two direc- tions; one concerns the power source and the other concerns desalination process type. Each coupling description and its results will be explained in the followings:
Pressurized water reactor (PWR) is the most common reactor type in operation today. Many different design configurations exits, but all have in common the use of light water as both coolant and moderator for the reactor core [6]. The reactor effi- ciency in this case is about 33%. Results are plotted for PWR-
600 evaluation are presented in figure1.
It is the second most common type of electricity-generating nuclear reactor after the PWR. The BWR reactor typically al- lows bulk boiling of the water in the reactor. Current BWR reactors have electrical outputs of 570 to 1300 MWe. The reac- tor is about 34.5% efficient. Cost calculations are plotted in table 4 for BWR in 50,000 to 200,000 m3/d water production levels.
Pressurized heavy water reactor (PHWR) is characterized by a horizontally oriented core, with the fuel channels housed in individual small diameter pressure tubes through which heavy water (D2O) circulates as the primary coolant [7].
TABLE 5
Results of DEEP calculations for PHWR (5% interest rate
and intermediate loop)
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Pressure tubes are housed in a large diameter horizontal tank (calandria) containing low temperature, low pressure heavy water as the moderator. The reactor is about 36% efficient. DEEP results for PHWR plants in 600MWe are illustrated in table 5.
Gas turbine-modular high temperature reactor (GT-MHR) is an advanced reactor design, which integrates demonstrated high temperature gas cooled reactor (HTGR) and industrial gas-turbine technologies, to meet all Generation IV goals with significant margins [8]. It is a helium cooled direct-cycle nuc- lear power plant. The designers claim to have relatively high electricity production efficiency (~50%) and enhanced safety, economic, non-proliferation and environmental characteris- tics.
options are applicable and some of them are presently used to produce the majority of desalted water in the world. In this study, two conventional power production plants have been taken into consideration. Plants included two cooling options gas cycle and combined cycle electric production plants. Re- sult of DEEP calculations for these plants are in table (8).
TABLE 8
Results of DEEP calculations for Fossil power plant
TABLE 6
Results of DEEP calculations for GT-MHR (5% interest rate
and intermediate loop)
Table 6 is the results for 300 MW(e) power level. For such coupling configurations MSF water plant requires higher power or less water capacity.
Small Modular Reactors (SMRs) have been indicated as the most suitable size for the majority of nuclear desalination ap- plications. Large-scale deployment of solid-uranium-fueled nuclear reactor desalination on a commercial basis will de- pend primarily on economic factors. SMRs is very flexible and appears to be particularly suitable for cogeneration of electrici- ty and water in relatively weak or non-interconnected electric- ity grids. Table (7) gives an overview for DEEP results. MSF process needs higher energy in such coupling configurations.
TABLE 7
Results of DEEP calculations for SMR (5% interest rate and
intermediate loop)
Power option | Desalina- tion plant size | Levelized electricity cost | Levelized water cost | |||
Power option | Desalina- tion plant size | Levelized electricity cost | MED | MSF | RO | Hyb |
SMR 130 | 50,000 | 0.063 | 0.487 | - | 0.8 | 0.639 |
SMR 130 | 100,000 | - | - | 0.788 | 0.626 | |
SMR 330 | 50,000 | 0.064 | 0.478 | 2.746 | 0.799 | 0.635 |
SMR 330 | 100,000 | 0.465 | - | 0.787 | 0.622 | |
SMR 330 | 200,000 | - | - | 0.778 | 0.612 |
Heat or electricity to be used for desalination purposes may be produced by burning conventional fuels. Several power plant
Coupling configuration between desalination and nuclear power plants not only entails technical and safety considera- tions but also it has a strong influence on the overall econom- ics of a nuclear desalination system. Accordingly, for each power/desalination plant combination the detailed input pa- rameters included different connection scenarios for evaluat- ing the competing influence of factors such as reactor type and size, desalination type and plant capacity, interest /discount rate, transport cost, carbon tax and gas price are examined for this analysis.
DEEP cost evaluation cases have been concluded to be pre- sented in figures (1) to (5). Figures 1, 2 compare between NPP plants which are engaged in co-generation scenarios in term of produced water cost. In figures 3, 4 two power plants sizes
600, 1000 MWe are added to the comparison. Figure (5) illu- strates electricity cost comparison for different energy sources.
Fig. 1. Water cost for three water cooled NPP and 600 MWe
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Fig. 2. Water cost for 1-MED, 2-MSF, 3-RO for 600MWe NPPs
Fig. 3. Water cost comparison for three water cooled NPP and
600, 1000 MWe
Fig. 4. Water cost comparison for different energy sources
Fig. 5. Electricity cost comparison for different energy sources
The results from DEEP simulation verified that as the water plant capacity increases water cost decreases for all type of desalination. Figures 6 to 8 are samples for these results.
Fig. 6. Change in water costs for 50,000 - 200,000 m3/d in
MED plant
Fig. 7. Changes in water costs for 50,000 - 200,000 m3/d in
MSF plant
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Fig. 8. Change in water costs for 50,000 - 200,000 m3/d in RO
plant
Figure 9 shows the difference in water cost for different desa-
lination plants type, and figure 10 explains the effect of NPP
energy levels on water cost for the same desalination plant.
Table 9 is a registered outcome for energy consumption while
DEEP operations for all desalination types. MED thermal de-
salination uses 6.38 KWh per cubic meter electrical energy;
whereas MSF uses about double the electrical consumption
than MED does and RO uses 3.17kWh/m3 as it is detected
from DEEP simulation models.
TABLE 9
Energy Requirements for Different Desalination Processes
Process/energy type | MED | MED+RO | MSF | MSF+RO | RO |
Electric energy equivalent kwhr/m3 | 4.75 | 2.33 | 10.46 | 5.3 | 0 |
Electric energy con- sumption kwhr/m3 | 1.63 | 2.4 | 2.1 | 4.8 | 3.17 |
Total electric energy equivalent kwhr/m3 | 6.38 | 4.73 | 12.56 | 10.1 | 3.17 |
Fig. 9. Water cost for different plant capacity
Fig. 10. Water cost for different desalination plant type in dif- ferent plant energy
As a test case for discount/interest rate (DR) effect on electrici- ty and water price DEEP cost analysis for PHWR model at
50,000 m3/d water capacity has been run for three DR values (5%, 8%, 10%), the results are in figures 11, 12. The results ex- plained the behavior of such economic sample but it can be generalized to study all coupling configurations.
Electricity cost versus water cost for different discount rates for the PHWR are concluded from DEEP results in figure 11. Electricity cost at 10% discount rate is about 63% higher than the corresponding cost at 5%DR for fixed plant power.
Figure 12 explains the effect of DR increases on water price for
different desalination processes. Water cost at 10% discount
rate is about 53% higher than the corresponding cost at 5%DR
in MSF, and 51% in MED and 36% in RO.
Fig. 11. Effects of Discount Rate in electricity and water price for PHWR at 50,000 capacity
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Fig. 12. Effects of Discount Rate in water price for PHWR at
50,000 capacity and different Desalination types
An energy and water plant is designed to answer a specific demand requirement that varies between winter and summer at that plant’s location. In North African countries summer electricity demand is much higher than winter de- mand, while water demand is almost stable all year long. For this reason and for high efficient NPP consideration there is a large potential for medium- to high capacity plant (50,000 –
200,000 m3/day) fixed / transportable desalination plants coupled to nuclear plants in this area. Figure 13 concludes a test model for verifying water transmission effect on water price for different desalination plant capacity. As it is expected from results water transmission adds cost to the produced water price, also as capacity increases transportable water cost decreases (water cost for 200,000 m3/d transportable water plant is almost the same as 50,000 m3/d fixed water plant).
Fig. 13. Desalination plant in fixed and transportable water production
• Water Desalination cost in case of nuclear reactors coupled to MED is 32% to 45% lower than the corresponding cost by the conventional power + MED systems.
• Water Desalination cost in case of nuclear reactors coupled to RO 28% to 35% lower than the corresponding cost by the conventional power + RO systems.
• Water Desalination cost in case of nuclear reactors
coupled to MSF 15% to 42% lower than the corresponding cost
by the conventional power + MSF systems.
• The combination of RO and MED or MSF technolo-
gies in the tested hybridized desalination plants provide sev-
eral important advantages:
• Hybrid RO + MED and RO + MSF plants produce
cheaper water than MED or MSF thermal desalination-only
plants
• Water Desalination cost in case of nuclear reactors
coupled to hybrid plant (MED + RO) is 28% to 43% lower than
the corresponding cost by the conventional power coupled to
hybrid (MED + RO) systems.
• The desalination cost of nuclear reactors coupled to
hybrid plant (MSF + RO) is 24% to 33.5% lower than the cor-
responding cost by the conventional power coupled to hybrid
(MSF + RO) systems.
• This cost is likely to be further reduced as a system
capacity is increased.
• Plant management economic aspects details- such as
discount/interest rate are essential for cost calculations.
• Intermediate loop is essential for NPP coupling to de-
salination plant but it adds cost to water price
• Fixed or portable water production is an important
choice and should be optimized with plant capacity.
• The lowest costs with the MED plants are obtained by
the GT-MHR, utilizing virtually free waste heat give desalina-
tion costs which are respectively 62% and 44% lower.
Reactor types and sizes that are commercially available offer- ing wide range of technical specifications which have to be verified for most suitable for each specific case and site. The choice of a reactor type for a dual purpose or co-generation plant should also be carefully chosen as a possible long-term investment project. Analysis results indicate that the discount rate has a great effect on water cost especially for nuclear energy source than for conventional energy source based desa- lination because of the high capital cost and relatively long construction periods in NPP. Fuel price changes affect water price in fossil plant rather than in nuclear options. If the eco- nomic performances of the GTMHR as one of the high tem- perature reactors for 4G generation, as announced by their respective developers, are indeed true that the GT-MHR would lead to the lowest water costs of all options considered. For high efficient NPP consideration there is a large potential for medium- to high capacity plant fixed / transportable desa- lination plants coupled to nuclear plants especially for North Africa Cost area.
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International Journal of Scientific & Engineering Research Volume 4, Issue 4, April -2013
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The author gratefully acknowledge IAEA support through the professional IT group who are working on software simula- tors DEEP and DE-TOP for freely download software and scientific support.
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[2] IAEA, Nuclear Desalination News Letter, “News from the Technical Working
Group on Nuclear Desalination” No. 3, September 2011
[3] IAEA, “Optimization of the Coupling of Nuclear Reactors and Desalination
Systems”, (IAEA-TECDOC -1444)June 2005
[4] IAEA, “Status of Nuclear Desalination in IAEA Member States” (IAEA- TECDOC-1524)January 2007
[5] IAEA, “Design Concepts of Nuclear Desalination Plants” (IAEA-TECDOC-
1326) November 2002
[6] IAEA, “Examining the economics of seawater desalination using the DEEP
code” (IAEA-TECDOC-1186) November 2000
[7] IAEA, “Managing the First Nuclear Power Plant Project” (IAEA-TECDOC-
1155)May 2007
[8] S. Nisan, S. Dardour, “Economic evaluation of nuclear desalination systems” Desalination 205 (2007) 231–242, www.elsevier.com/locate/desal
1122
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