Nuclear-Power

Hindawi Publishing Corporation International Journal of Nuclear Energy Volume 2014, Article ID 793908, 7 pages http://dx.doi.org/10.1155/2014/793908

Research Article The Impact of Climate Changes on the Thermal Performance of a Proposed Pressurized Water Reactor: Nuclear-Power Plant Said M. A. Ibrahim,1 Mohamed M. A. Ibrahim,2 and Sami. I. Attia2 1 2

Department of Mechanical Power Engineering, Faculty of Engineering, AL-Azhar University, Nasr City, Cairo 11371, Egypt Nuclear Power Plants Authority, 4 El-Nasr Avenue, P.O. Box 8191, Nasr City, Cairo 11371, Egypt

Correspondence should be addressed to Sami. I. Attia; eng [email protected] Received 17 February 2014; Accepted 14 March 2014; Published 10 April 2014 Academic Editor: Massimo Zucchetti Copyright © 2014 Said M. A. Ibrahim et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This paper presents a methodology for studying the impact of the cooling water temperature on the thermal performance of a proposed pressurized water reactor nuclear power plant (PWR NPP) through the thermodynamic analysis based on the thermodynamic laws to gain some new aspects into the plant performance. The main findings of this study are that an increase of one degree Celsius in temperature of the coolant extracted from environment is forecasted to decrease by 0.39293 and 0.16% in the power output and the thermal efficiency of the nuclear-power plant considered, respectively.

1. Introduction The main use of water in a thermoelectric power plant is for the cooling system to condense steam and carries away the waste heat as part of a Rankine steam cycle. The total water requirements of the plant depends on a number of factors, including the generation technology, generating capacity, the surrounding environmental and climatic conditions, and the plant’s cooling system, which is the most important factor governing coolant flow rate. Thermal power plants are built for prescribed specific design conditions based on the targeted power demand, metallurgical limits of structural elements, statistical values of environmental conditions, and so forth. At design stage, a cooling medium temperature is chosen for each site considering long term average climate conditions. However, the working conditions deviate from the nominal operating conditions in practice. For this reason, efficiency in electricity production is affected by the deviation of the instantaneous operating temperature of seawater cooling water of a nuclear power plant from the design temperature of the cooling medium extracted from environment to transfer waste heat to the atmosphere via a condenser. Present nuclear plants have about 34–40% thermal efficiency, depending on site (especially water temperature).

The cooling process in nuclear power plants requires large quantities of cooling water. The huge amounts of water withdrawal and consumption cause that the electricity has to face the impacts of climate change, that is, in form of increasing sea temperatures or water scarcity. For instance, if seas exhibit too high water temperatures, the continued use of water for cooling purposes may be at risk because the cooling effect decreases and also water quality regulations could be violated. An increase in the temperature of cooling water may have impact on the capacity utilization of thermal power plants in two concerns: (1) reduced efficiency: increased environmental temperature reduces thermal efficiency of a thermal power plant, (2) reduced load: for high environmental temperatures, thermal power plant’s operation will be limited by a maximum possible condenser pressure. The operation of plants with river or sea cooling will in addition be limited by a regulated maximum allowable temperature for the return water or by reduced access to water. In the literature, there are few works published to identify these climate change impacts, and few have tried to quantify them. Ganan et al. [1] studied the performance of the pressurized-water reactor- (PWR-) type Almaraz nuclearpower plant and showed that it is strongly affected by the weather conditions having experienced a power limitation

2 due to vacuum losses in condenser during summer. Durmayaz and Sogut [2] presented a theoretical model to study the influence of the cooling water temperature on the thermal efficiency of a conceptual pressurized-water reactor nuclearpower plant. Sanathara et al. [3] gave a parametric analysis of surface condenser for 120 MW thermal power plant and focus on the influence of the cooling water temperature and flow rate on the condenser performance and thus on the specific heat rate of the plant and its thermal efficiency. Daycock et al. [4] measured the actual decrease in efficiencies of gas power plants located in a desert. Linnerud et al. [5] concluded that a rise in temperature may influence the capacity utilization of thermal power plants in two ways. Chuang and Sue [6] studied the performance effects of combined cycle power plant with variable condenser pressure and loading. Costle and Finn [7] reviewed the evaporative cooling technique in temperature maritime climate. In this study, an energy analysis is performed to evaluate the impact of the change in cooling medium temperature on the thermal efficiency of a PWR NPP. The objective is to establish a theoretical methodology to assess the plant performance in different climatic conditions and to emphasize the importance of plant site selection from the environmental temperature point of view. A model for condenser heat balance is developed to determine the functional relationship between the cooling water temperature and the condenser pressure considering that saturation condition exists in the condenser and there is a finite amount of temperature differences between this saturation temperature and the cooling water exit temperature. Employing this condenser heat balance model, a cycle analysis is carried out to determine the heat balance conditions and corresponding power output and thermal efficiency for the prescribed range of cooling water temperatures.

2. Methodology The development of a mathematical model depends upon studying, analysis, and evaluation of the thermal performance and thermodynamics of the secondary cycle of nuclear power plant. This model describes how the impacts of climatic variables and conditions of environment affect the temperature marginal limits of condenser cooling water and the extent of its impacts on the efficiency and performance of the nuclear plant. The thermal and thermodynamic properties, parameters, variables, and mathematical relationships will be formulated to determine the thermal efficiency through the application of the energy and mass conservation laws that govern the mass and heat balance. Figure 1 illustrates a diagram of a proposed PWR nuclear power plant, to address the thermodynamic and heat balance analysis of a PWR NPP. Typical PWR consists of a primary cycle which includes nuclear reactor, steam generator, pressurizer, and reactor coolant pump and the secondary cycle which consists of high-pressure steam turbine (HPST), three low-pressure steam turbines (LPST), moisture separator and reheater (MS/R), deaerator feed water heater, two high-pressure feed water heaters (HPFWH), and three

International Journal of Nuclear Energy low-pressure feed water heaters (LPFWH), condenser, and necessary pumps (feed water pump and condensate pump). A computer program based on the mathematical model representing the secondary circuit of the plant and its components was performed using the engineering equation solver computer program (EES) [8]. The algorithm procedures are performed as follows. (i) Thermodynamic properties (pressure (P), temperature (T), entropy (S), enthalpy (h), and moisture content (X)) at all the inlet and exit of all parts and components of the plant. (ii) Heat balance for each feed water heater and the steam generator. (iii) Output useful work of the turbines and pumps. (iv) Calculation of the amount of heat added to generate steam, as well as the amount of heat rejected from condenser, and calculation of the efficiency of the station. (v) Hence temperature entropy (T-S) diagram of the plant and its components, as well as numerical tabulation of results, being reported. (vi) Determination of the cooling water inlet temperature (𝑇in ) and exit temperature (𝑇out ) and the temperature difference. (vii) Assigning the range of change of cooling water temperature 𝑇cwi during the entire year for the Mediterranean sea as (15–30∘ C). (viii) Computing the impact of the changes of cooling water temperature 𝑇cwi on the thermal efficiency 𝜂th and output work 𝑊net of the plant. (ix) Drawing the relation of 𝑇cwi versus 𝜂th and 𝑊net of the plant. The energy balance equations for the various processes involving steady-flow equipment such as nuclear reactor, turbines, pumps, steam generators, heaters, coolers, reheaters, and condensers in a PWR NPP are as follows. 2.1. Heat Balance Equations (i) The total turbine work, 𝑊T , kJ/kg, is as follows: 𝑊T = 𝑊HPT + 𝑊LPT 𝑊HPT = 𝑚̇ st (ℎin − ℎout )

(1)

𝑊LPT = 𝑚̇ st (ℎin − ℎout ) , where 𝑚̇ st is steam mass flow rate inlet to each turbine, kg/s, ℎin is enthalpy of steam inlet to each turbine, kJ/kg, ℎout is enthalpy of steam outlet from each turbine, kJ/kg, 𝑊HPT is high pressure turbine work, kJ/kg, and 𝑊LPT is low pressure turbine work, kJ/kg.

International Journal of Nuclear Energy

3

1

2 6

MS

Reheater

8

10

3 S.G

9

HPT

LPT

Hot leg

7 14 Deaerator

Reactor core

5

4

Condenser 11 12

13 15

Cold leg

RCP

23

19 20 21 fwp

22 1HPFWH

2HPFWH

18 3LPFWH

17 4LPFWH

16

cp

5LPFWH

Figure 1: Diagram of PWR nuclear power plant.

(ii) The pumping work, 𝑊p , kJ/kg, is as follows:

(vi) The cycle efficiency, 𝜂th , %, is as follows:

𝑊p = 𝑊cp + 𝑊fwp 𝑊fwp = 𝑚̇ fw (ℎin − ℎout )

𝜂th = (2)

where 𝑚̇ fwh is steam mass flow rate inlet to each turbine, kg/s, ℎin is enthalpy of steam inlet to each Turbine, kJ/kg, ℎout is enthalpy of steam outlet from each turbine, kJ/kg, 𝑊fwp is high pressure turbine work, kJ/kg, and 𝑊cp is low pressure turbine work, kJ/kg. (iii) Heat added to steam generator, 𝑄add , kJ/kg, is as follows: (3)

where 𝑚̇ st is steam mass flow rate exit from steam generator, kg/s, ℎin is enthalpy of feed water inlet to steam generator, kJ/kg, and ℎout is enthalpy of steam outlet from steam generator, kJ/kg. (iv) Heat rejected from condenser, 𝑄Rej , kJ/kg, is as follows: 𝑄Rej = (𝑚̇ mix ∗ ℎin − 𝑚̇ mix ∗ ℎout ) ,

(4)

where 𝑚̇ mix is mixture mass flow rate through condenser, kg/s, ℎin is enthalpy of mixture inlet to condenser, kJ/kg, and ℎout is enthalpy of feed water outlet from condenser, kJ/kg.

(i) Closed feed water heaters are as follows: 𝑚̇ st ∗ (ℎ1 − ℎ2 ) = 𝑚̇ fw ∗ (ℎout − ℎin ) ,

(5)

(7)

where 𝑚̇ st is steam mass flow rate extracted from turbine to feed water heater, kg/s, 𝑚̇ fwh is steam mass flow rate inlet to feed water heater, kg/s, ℎ1 is enthalpy of steam inlet to feed water heater, kJ/kg, ℎ2 is enthalpy of steam outlet from feed water heater, kJ/kg, ℎin is enthalpy of mixture inlet to feed water heater, kJ/kg, and ℎout is enthalpy of feed water outlet from feed water heater, kJ/kg. (ii) Deaerator is as follows: (𝑚̇ st + 𝑚̇ fw ) ∗ ℎout = (𝑚̇ st ∗ ℎ1 ) + (𝑚̇ fw ∗ ℎin ) ,

(8)

where 𝑚̇ st is steam mass flow rate extracted from turbine to feed water heater, kg/s 𝑚̇ fwh is steam mass flow rate inlet to feed water heater, kg/s, ℎin is enthalpy of mixture inlet to feed water heater, kJ/kg, and ℎout is enthalpy of feed water outlet from feed water heater, kJ/kg. 2.3. Heat Balance of Steam Generator. Consider 𝑚̇ RCW ∗ 𝐶RCW ∗ (𝑇HL − 𝑇CL )

(v) Network done, 𝑊net , kJ/kg, is as follows: 𝑊net = 𝑊𝑇 − 𝑊p .

(6)

2.2. Heat Balance of Feed Water Heaters

𝑊cp = 𝑚̇ fw (ℎin − ℎout ) ,

𝑄add = 𝑚̇ st (ℎout − ℎin ) ,

𝑊net . 𝑄add

= (𝑚̇ st ∗ ℎout ) − (𝑚̇ fw ∗ ℎin ) ,

(9)

4


where 𝑚̇ RCW is reactor coolant water mass flow rate of primary circuit, kg/s, 𝑚̇ fw is feed water mass flow rate inlet to steam generator, kg/s, 𝑚̇ st is steam mass flow rate outlet from steam generator, kg/s, ℎin is enthalpy of feed water inlet to steam generator, kJ/kg, ℎout is enthalpy of steam outlet from steam generator, kJ/kg, 𝑇HL is temperature of reactor coolant g water at hot leg, ∘ C, 𝑇CL is temperature of reactor coolant g water at cold leg, ∘ C, and 𝐶RCW is specific heat of reactor coolant water of primary circuit, kJ/kg⋅K. 2.4. Heat Balance of Moisture Separator and Reheater. Consider 𝑚̇ st ∗ ℎin = (𝑚̇ st ∗ ℎ𝑠 ) + (𝑚̇ fw + 𝑚̇ st ) ∗ ℎout ,

(10)

where 𝑚̇ st is steam mass flow rate inlet to moisture separator and reheater, kg/s, 𝑚̇ 𝑠 is water mass flow rate exit from moisture separator and reheater to feed heater, kg/s ℎin is enthalpy of feed water inlet to moisture separator and reheater, kJ/kg, ℎout is enthalpy of steam outlet from moisture separator and reheater, kJ/kg, and ℎ𝑠 is enthalpy of steam outlet from moisture separator and reheater, kJ/kg. 2.5. Heat Balance of Cooling Water System (Condenser). The condenser is a large shell and tube type heat exchanger. The steam in the condenser goes under a phase change from vapor to liquid water. External cooling water is pumped through thousands of tubes in the condenser to transport the heat of the condensation of the steam away from the plant. Upon leaving the condenser, the condensate is at a low temperature and pressure. The phase change in turn depends on the transfer of heat to the external cooling water. The rejection of heat to the surrounding by the cooling water is essential to maintain the low pressure in the condenser. The heat is absorbed by the cooling water passing through the condenser tubes. The rise in cooling water temperature and mass flow rate is related to the rejected heat as 𝑄Rej = (𝑚̇ mix ∗ ℎin ) − (𝑚̇ fw ∗ ℎout ) 𝑄Rej = 𝑚̇ CW ∗ 𝐶 ∗ Δ𝑇

(11)

Δ𝑇 = (𝑇cwo − 𝑇cwi ) , where 𝑚̇ CW is cooling water mass flow rate of condenser, kg/s, 𝑚̇ fw is feed water mass flow rate of outlet from condenser, kg/s, 𝑚̇ mix is mixture mass flow rate of inlet to condenser, kg/s, ℎ𝑖 is enthalpy of mixture inlet to condenser, kJ/kg, ℎout is enthalpy of feed water outlet from condenser, kJ/kg, 𝑇𝑐 is condenser saturation temperature, ∘ C, 𝑇cwo is temperature of cooling water outlet from condenser, ∘ C, 𝑇cwi is temperature of cooling water inlet to condenser, ∘ C, ΔT is temperature difference between the cooling water exit and inlet temperature, ∘ C, and Δ𝑇hot is temperature difference between the saturation temperature and the cooling water exit temperature, ∘ C. Modeling assumptions for the secondary cycle are as follows. (i) The thermodynamic conditions of steam at exit of the SG are fixed.

(ii) Thermal power of the PWR changes slowly to provide constant thermodynamic properties of steam at exit of the SG since the variation in cooling water temperature occurs seasonally and very slowly. (iii) The condenser vacuum varies with the temperature of cooling water extracted from environment at fixed mass flow rate into the condenser. (iv) There are constant mass flow rates of condensate and cooling water. (v) There is no pressure drop across the condenser. (vi) The potential and kinetic energies of the flow and heat losses from all equipment and pipes are negligible.

3. Results and Discussions Thermodynamic analysis of the proposed PWR NPP is conducted to investigate the key parameters such as heat added to steam generator, heat rejection, net turbine work, and overall thermal efficiency. Figure 2 illustrates the calculation of the thermodynamic and heat balance analysis of the proposed PWR NPP. Figure 3 showed the thermodynamic and heat balance analysis of the proposed PWR NPP, on the T-S diagram of steam Rankine cycle as obtained from the heat balance of the plant. Table 1 summarizes the calculation of the thermodynamic properties at design conditions satisfying the heat balance for the proposed PWR NPP. Figure 2 and Table 1 are the basis of the parametric study and analysis of the present work. A parametric study is performed to determine the saturation temperature T 𝐶, corresponding condensate pressure P𝐶, and also the cooling water exit temperature 𝑇cwe for the cooling water inlet temperature 𝑇cwi and condenser terminal temperature difference (T 𝐶 − 𝑇cwe ) by using the condenser heat balance model. The results are given in Figures 4 and 5. Figure 4 shows that the relation between 𝑇cwi and 𝑇cwe exhibits a proportional linear variation with no effect of the condenser terminal temperature difference (T 𝐶 − 𝑇cwe ). The variation of T 𝐶 with 𝑇cwi also shows a linear dependency having approximately 1∘ C difference in T 𝐶 for subsequent condenser terminal temperature difference (T 𝐶 −𝑇cwe ) values at any constant value of 𝑇cwi . Figure 4 depicts the variation between cooling water exit temperature 𝑇cwe and saturation temperature T 𝐶 in condenser with cooling water inlet temperature 𝑇cwi . 𝑇cwi increases, the saturation temperature T 𝐶 increases, and this affect the output work and consequently the efficiency. Figure 5 illustrates variation of the saturation pressure P𝐶, corresponding to the saturation temperature T 𝐶, with cooling water inlet temperature 𝑇cwi . It is seen that an increase in 𝑇cwi of 1∘ C, 5∘ C, 10∘ C, and 15–30∘ C results is an increase in P𝐶 of 0.00238, 0.01215, 0.02989, and 0.051 bar, respectively. Figure 6 presents the variation of thermal efficiency 𝜂th with cooling water inlet temperature 𝑇cwi . When 𝑇cwi increases by 1∘ C, 5∘ C, 10∘ C, and (15–30∘ C), the thermal efficiency 𝜂th decreases by 0.16, 0.76, 1.52, and 2.27%, respectively.


5 1

2 73.8 289.5 1437 2763

73.8 289.5 0.9975 2763

73.8 289.5 171.1 2763 6

3

9.932 289.5 1008 3028

Moisture separator

1355 2478

LP turbine

HP turbine 9.932 179.6 176 761.5 41.68 252.8 153 2678

S.G

5

73.8 289.5 171.1 1286

7

11 13 13 1.267 106.4 64.21 2689

0.3088 69.78 52.42 2510

14

0.05079 33.16 821.6 2.314

34

73.8 212.2 1608 909.6 2nd HP.F.W.H

1st HP.F.W.H

22

24

21.55 216.2 153 1099

21

Core

R.C. pump

12 12

3.93 199.5 69.45 2859

73.8 289.5 171.1 1286

LP turbine

11

100.7 2583

73.8 248.8 1608 1080

23

LP turbine

9

21.55 216.2

Deaerator

Control rod

4

10

9.932 179.6 1008 2777

9.932 179.6

Pressurizer

Reheater

8

25

F.W. pump

26

21.55 216.2 73.8 181 253.7 926.1 1608 771.1

41.68 252.8 153 1099

2 30 41197 125.8

19

9.932 65.75 1008 276

9.932 102.4 1008 429.7

9.932 139 1008 585.3 3rd LP.F.W.H

18

4th LP.F.W.H

17

27

9.932 179.6 133.7 926.1

9.932 179.6 1184 761.5

28

1.267 106.4 69.45 602.1

3.93 143 69.45 602.1

29

30 1.267 106.4 133.7 446

0.3088 69.75 133.7 446

Condenser 35

5th LP.F.W.H 16

20

36

9.932 33.27 1008 140.2

31

C. pump

15

33

0.05079 33.16 1008 138.9

0.05079 33.16 186.1 292

3 20 41197 84.12

32

0.3088 69.75 186.1 292

Reactor vessel Pressure (bar) Temperature (∘ C)

Primary circuit

Flow rate (kg/s) Enthalpy (kJ/kg)

Secondary circuit

Figure 2: Illustration of the EES model equivalent to the proposed PWR NPP thermodynamic and heat balance analysis.

0.11

400 350

32 31 20 19 22 21 18 17 23 16

250 200 150 100 50

12 11

1

41.68 bar

2

21.55 bar

3

9.932 bar

4

24 15

3.93 bar

26 14 25 28 27 13 29

1.267 bar

0 0

73.8 bar

1

6

0.08 5 7 8

0.2

2

0.4

3

10 0.6

4 5 S (kJ/kg·K)

0.05

0.8

6

7

0.07 0.06

9

0.3088 bar 0.05079 bar

0.09

Pc (bar)

T (∘ C)

0.1

30

300

8

9

0.04 0.03

Figure 3: T-S diagram of the proposed PWR nuclear power plant thermodynamic and heat balance analysis.

15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Tcwi (∘ C) TTD = 3∘ C TTD = 4∘ C TTD = 5∘ C

Figure 5: Variation of saturation pressure P𝐶 , corresponding to the saturation temperature T 𝐶 , with cooling water inlet temperature 𝑇cwi .

50

Tcwe , Tc (∘ C)

45 40 35 30 25 20 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Tcwi (∘ C) Tcwe TTD = 3∘ C

TTD = 4∘ C TTD = 5∘ C

Figure 4: Variations of cooling water exit temperature 𝑇cwe and saturation temperature T 𝐶 with cooling water inlet temperature 𝑇cwi .

Figure 7 gives the variation of net power output 𝑊̇ net with cooling water inlet temperature 𝑇cwi . An increase in 𝑇cwi of 1∘ C, 5∘ C, 10∘ C, and 10–35∘ C corresponds to decrease in 𝑊̇ net by 0.39293, 2.166, 4.3683, and 6.547%, respectively. The change of condenser conditions, that is, 𝑇C and P𝐶, with 𝑇cwi results in a decrease of 6.547% in output power of the plant 𝑤̇ net for the 𝑇cwi range of 15–30∘ C as shown in Figure 7. It is observed from Figure 6 that an increase from 15 to 30∘ C in the temperature of the coolant extracted from environment results in a decrease from 37.57 to 35.3% in the thermal efficiency of the NPP.

4. Conclusions A condenser heat balance model is developed to determine the functional relationship between the cooling water temperature and the condenser pressure. Thus, a cycle analysis

6

International Journal of Nuclear Energy Table 1: Thermodynamic data for the proposed pressurized water reactor nuclear power plant. Temperature, 𝑇 (∘ C)

Pressure, 𝑃 (bar)

Enthalpy, ℎ (kg/kj)

Entropy, 𝑆 (kj/kg⋅k)

Quality, 𝑥

1

289.5

73.8

2763

5.779

0.9975

2

289.5

73.8

2763

5.779

0.9975

171.1

Station number

Mass flow rate, 𝑚̇ (kg/s) 1608

3

289.5

73.8

2763

5.779

0.9975

1437

4

252.8

41.68

2678

5.82

0.9283

153

5

216.2

21.55

2583

5.868

0.8841

100.7

6

179.6

9.932

2478

5.926

0.8513

1355

7

179.6

9.932

761.5

2.136

0

176

8

179.6

9.932

2777

6.588

1

1008

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

289.5 289.5 199.5 106.4 69.78 33.16 33.16 33.27 65.75 102.4 139 179.6 181 212.2 248.8 252.8 216.2 216.2 179.6 143 106.4 106.4 69.75 69.75 33.16 252.8 20 30

73.8 9.932 3.93 1.267 0.3088 0.05079 0.05079 9.932 9.932 9.932 9.932 9.932 73.8 73.8 73.8 41.68 21.55 21.55 9.932 3.93 1.267 1.267 0.3088 0.3088 0.05079 41.68 3 2

1286 3028 2859 2689 2510 2314 138.9 140.2 276 429.7 585.3 761.5 771.1 909.6 1080 1099 1099 926.1 926.1 602.1 602.1 446 446 292 292 1286 84.12 125.8

3.154 7.085 7.177 7.288 7.419 7.579 0.4799 0.481 0.9022 1.333 1.728 2.136 2.141 2.436 2.774 2.819 2.836 2.483 2.499 1.77 1.79 1.378 1.401 0.9519 0.9796 3.174 0.2961 0.4365

0 Superheated Superheated Superheated 0.9503 0.8978 0 Sub. liquid Sub. liquid Sub. liquid Sub. liquid 0 Sub. liquid Sub. liquid Sub. liquid 0 0.09234 0 0.08166 0 0.0697 0 0.06599 0 0.06319 0.11 Sub. liquid Sub. liquid

171.1 1008 69.45 64.21 52.42 821.6 1008 1008 1008 1008 1008 1184 1608 1608 1608 153 153 253.7 133.7 69.45 69.45 133.7 133.7 186.1 186.1 171.1 41197 41197

for the proposed NPP is carried out to determine the heat balance conditions originating from temperature change of cooling medium. It can be concluded that the output power and the thermal efficiency of the plant decrease by approximately 0.3929 and 0.16%, respectively, for 1∘ C increase in temperature of the condenser cooling water extracted from the environment. The impact of climate changes in condenser cooling water is an important design consideration when constructing

PWR NPP. A reduction in production capacity due to an increase in environment temperature would represent a drop of production that might need to be replaced somewhere. The effect of climatic changes shows to be important in the design of more effective cooling technique and to device methods to compensate for the loss in plant output and system capacity. Climate considerations will also become even more important when deciding where to build new thermal power plants.


1.05E + 06

cp: CW: cwi: CL: cwo: fw: fwp: HL: HPT: LPT: in: mix: out: p: RCW: Rej: T: .: HP: LP: NPP: PWR: RC: SG:

1.03E + 06

Conflict of Interests

1.00E + 06

The author declares that there is no conflict of interests regarding the publication of this paper.

9.75E + 05

References

38 37.5

𝜂th (%)

37 36.5 36 35.5 35 34.5 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Tcwi (∘ C) TTD = 3∘ C TTD = 4∘ C TTD = 5∘ C

Figure 6: Variation of thermal efficiency 𝜂th with cooling water inlet temperature 𝑇cwi .

Ẇ net (watt)

7

9.50E + 05 9.25E + 05

15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Tcwi (∘ C) TTD = 3∘ C TTD = 4∘ C TTD = 5∘ C

Figure 7: Variation of net power output 𝑊̇ net with cooling water inlet temperature 𝑇cwi .

Nomenclature C: h: 𝑚:̇ p: 𝑄:̇ T: TTD: 𝑊̇ net : 𝜂: add: c:

Specific heat (kJ/kg⋅K) Enthalpy (kJ/kg) Mass flow rate (kg/s) Pressure (bar) Net rate of heat transferred (kW) Temperature (K) Terminal temperature difference Net rate of work (kW) Efficiency (%) Added Condenser

Condensate pump Cooling water Cooling water inlet Cold leg Cooling water outlet Feed water Feed water pump Hot leg High pressure turbine Low pressure turbine Inlet Mixture Outlet Pump Reactor cooling water Rejection Turbine Per unit time High pressure Low pressure Nuclear power plant Pressurized water reactor Reactor coolant Steam generator.

[1] J. Gañań, A. R. Al-Kassir, J. F. González, A. MacI´ıas, and M. A. Diaz, “Influence of the cooling circulation water on the efficiency of a thermonuclear plant,” Applied Thermal Engineering, vol. 25, no. 4, pp. 485–494, 2005. [2] A. Durmayaz and O. S. Sogut, “Influence of cooling water temperature on the efficiency of a pressurized-water reactor nuclear-power plant,” International Journal of Energy Research, vol. 30, no. 10, pp. 799–810, 2006. [3] V. Milan Sanathara, P. Ritesh Oza, and S. Rakesh Gupta, “Parametric analysis of surface condenser for 120 MW thermal power plant,” International Journal of Engineering Research & Technology, vol. 2, no. 3, 2013. [4] C. Daycock, R. Jardins, and S. Fennel, “Generation cost forecasting using on-line thermodynamic models,” in Proceedings of the Electric Power, Baltimore, Md, USA, March 2004. [5] K. Linnerud, T. K. Mideksa, and G. S. Eskeland, “The impact of climate change on nuclear power supply,” Energy Journal, vol. 32, no. 1, pp. 149–168, 2011. [6] C.-C. Chuang and D.-C. Sue, “Performance effects of combined cycle power plant with variable condenser pressure and loading,” Energy, vol. 30, no. 10, pp. 1793–1801, 2005. [7] B. Costle and D. P. Finn, Reviewed the Evaporative Cooling Technique in Temperature Maritime Climate, 2005. [8] http://www.fchart.com/.

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