# Repowering a Coal Power Plant Steam Cycle Using Modular Light-Water Reactor Technology

^{1}

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## Abstract

**:**

## 1. Introduction

## 2. Methods

#### 2.1. Selection of the Turbine for Cooperation with SMRs

^{2}.

#### 2.2. Modelling of the Steam Cycle

#### 2.2.1. Nuclear Retrofit Case with Modernization of the Original IP Section (Case A–C)

#### 2.2.2. Retrofit Case with New HP Section (Case D)

- -
- saturated steam parameters at the turbine inlet: pressure of 7 MPa and corresponding saturation temperature of 285 °C,
- -
- the LP section operating conditions will not change compared to design values: the steam mass flow and parameters upstream the LP section are the same as for the 460 MW turbine,
- -
- the pressure at the HP section exhaust is higher than the pressure at the LP inlet due to pressure losses in the moisture separator and in the steam reheater,
- -
- the deaerator pressure is equal to the design pressure value at the reference load,
- -
- the steam bleed parameters in the HP section make it possible to heat feed water at the inlet the steam generator to the assumed temperature of 230 °C.

#### 2.3. Economic Assessment

#### 2.3.1. Assessment Indicators

#### 2.3.2. Assumptions

_{el}.

## 3. Results

#### 3.1. Technical and Energy Performance Assessment Results

^{3}/kg for design conditions to 0.268 m

^{3}/kg after modernization. As a result of this change, the velocity of inlet steam to this exchanger will be only slightly lower than the design conditions (cf. Figure 15). Thus, the LPH4 feed-water heater can also be used in a new power unit. The mass flow rate of steam to the high-pressure feed-water heater (HPH) is two and a half times greater than for the 460 MW power unit operating conditions. However, due to the change in steam parameters, the velocity in the pipeline at the inlet to this exchanger would be about 160 percent higher for the new operating conditions (cf. Figure 14 and Figure 15). The use of this exchanger in the new power unit would therefore have to be preceded by an analysis of its operation in the new conditions.

#### Flow through Bypass of the IP–LP Section of the Turbine

#### 3.2. Economic Assessment Results

## 4. Discussion

## 5. Summary

## Author Contributions

## Funding

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## Appendix A

## References

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**Figure 1.**Turbine diagram for a nuclear power plant (SG—steam generator, HP—high-pressure section of a turbine, LP—low-pressure section of a turbine, S—moisture separator, R—reheater, G—generator).

**Figure 2.**Diagram of the 460 MW condensing turbine (HP—the high-pressure section of the turbine, LP—the intermediate-pressure section of the turbine, LP—the low-pressure section of the turbine).

**Figure 5.**Diagram of the steam cycle with marked calculation points after modernization of the power unit (SG—steam generator, HP—the high-pressure section, LP—the low-pressure section, S—the moisture separator, R—the reheater, G—the generator, (LPH1–LPH4)—the low-pressure feed-water heaters, HPH—the high-pressure feed-water heater, D—the deaerator, ST—the feed-water storage tank). red dashed line—components previously used in the coal-fired power unit.

**Figure 6.**Temperature distribution in the steam generator (green line—temperature of water in the reactor coolant system, red line—temperature of working medium in the steam turbine cycle (case without superheater), bleu line—temperature of working medium in the steam turbine cycle (case with superheater).

**Figure 7.**Steam expansion line in the turbine of the 460 MW power unit (REF) and post-modernization state (Casa A and Case C).

**Figure 9.**Steam expansion line in the turbine of the 460 MW power unit (REF) and post-modernization state (Case D).

**Figure 13.**Mass flow rate of steam at the inlet to the turbine for different parameters of steam feeding the turbine.

**Figure 14.**Steam mass flow rate to the feed-water heaters (heat exchanger labels as shown in Figure 5).

**Figure 15.**The velocity ratio of the steam flow in the pipeline to the heat exchangers (heat exchanger labels as shown in Figure 5).

**Figure 18.**NPV as a function of project lifetime for steam cycle modernization cost index MC

_{ST}= 0.5 for average level of RS.

**Figure 19.**NPV as a function of steam cycle modernization cost index for the three values of retrofit savings factor (

**left**—maximum,

**central**—average,

**right**—minimum).

**Figure 20.**NPVR as a function of steam cycle modernization cost index for the three values of retrofit savings factor (

**left**—maximum,

**central**—average,

**right**—minimum).

Case | Live Steam Pressure | Live Steam Temperature | Reheated Steam Temperature | Inlet Temperature to Boiler/SG | Boiler/SG Thermal Power |
---|---|---|---|---|---|

Original plant | 28 MPa | 560 °C | 580 °C | 290 °C | 957.1 MW |

Repowered plant | 7 MPa | 285 °C | Varies | Varies | Varies |

**Table 2.**Parameters at selected points in the cycle are presented in Figure 5.

Calculation Point | Parameters | Case A, No Reheater | Case B, 1-Stage Reheat | Case C, 2-Stage Reheat |
---|---|---|---|---|

0 | p, MPa | 4.058 | 4.035 | 4.035 |

t, °C | 251.2 | 285.0 | 285.0 | |

x, - | 1.0 | Superheated steam | Superheated steam | |

h, kJ/kg | 2800.6 | 2916.7 | 2916.7 | |

$\dot{m}$, kg/s | 356.096 | 337.788 | 339.281 | |

1 | p, MPa | 3.997 | 3.974 | 3.974 |

t, °C | 250.2 | 284.2 | 284.2 | |

x, - | 0.999 | Superheated steam | Superheated steam | |

h, kJ/kg | 2800.6 | 2916.7 | 2916.7 | |

$\dot{m}$, kg/s | 329.5 | 313.0 | 313.0 | |

6 | p, MPa | 0.589 | 0.589 | 0.589 |

t, °C | 158.1 | 158.1 | 158.1 | |

x, - | 0.890 | 0.930 | 0.930 | |

h, kJ/kg | 2525.7 | 2609.2 | 2609.2 | |

$\dot{m}$, kg/s | 272.003 | 260.257 | 260.488 | |

8 | p, MPa | 0.536 | 0.535 | 0.539 |

t, °C | 230.6 | 230.3 | 235.6 | |

x, - | Superheated steam | Superheated steam | Superheated steam | |

h, kJ/kg | 2919.3 | 2918.6 | 2929.6 | |

$\dot{m}$, kg/s | 244.533 | 244.489 | 244.706 | |

12 | p, MPa | 0.006 | 0.006 | 0.006 |

t, °C | 35.9 | 35.9 | 35.9 | |

x, - | 0.885 | 0.885 | 0.887 | |

h, kJ/kg | 2288.2 | 2287.8 | 2294.1 | |

$\dot{m}$, kg/s | 208.924 | 208.886 | 209.102 | |

25 | p, MPa | 4.509 | 4.483 | 4.483 |

t, °C | 212.1 | 211.5 | 211.5 | |

h, kJ/kg | 908.2 | 905.3 | 905.3 | |

$\dot{m}$, kg/s | 356.096 | 337.788 | 339.281 | |

Gross electric output, MW | 223.242 | 228.788 | 229.989 | |

Heat rate, kJ/kWh | 10,867.1 | 10,690.9 | 10,682.0 |

Based on the Conservation Equation | Based on the Stodola Equation | Absolute Difference | Relative Difference | |
---|---|---|---|---|

Steam pressure at the turbine inlet | 4.035 MPa | 4.356 MPa | 0.321 MPa | 7.96% |

Electric power | 228.8 MW | 234.4 MW | 5.6 MW | 2.45% |

Heat rate | 10,691 kJ/kWh | 10,539 kJ/kWh | 152 kJ/kg | −1.42% |

Calculation Point | p [MPa] | t/x [°C/-] | h [kJ/kg] | m [kg/s] |
---|---|---|---|---|

0 | 7.000 | 285.830 | 2772.6 | 406.865 |

1 | 6.895 | 284.531 | 2772.6 | 365.100 |

2 | 6.930 | 284.959 | 2772.6 | 41.765 |

6 | 0.589 | 0.833 | 2406.1 | 290.584 |

7 | 0.571 | 0.990 | 2733.1 | 244.428 |

8 | 0.554 | 265.151 | 2990.9 | 244.428 |

12 | 0.006 | 0.901 | 2326.7 | 209.031 |

25 | 7.778 | 230.000 | 991.2 | 406.865 |

Gross power output | 267.018 | kW | ||

Heat rate | 9771.5 | kJ/kWh |

**Table 5.**Overall capital costs and total indirect costs for respective components of investment subject [10].

Component of Costs | Category | Symbol of Component | Budgeted Share *, % | Minimal Retrofit Savings, % | Mid-Level Retrofit Savings, % | Maximum Retrofit Savings, % |
---|---|---|---|---|---|---|

- | i | ${sOCC}_{\mathrm{i}}$ or $sTIC$ | ${\left({RS}_{{OCC}_{\mathrm{i}}}\right)}_{\mathrm{m}\mathrm{i}\mathrm{n}}$ or ${\left({RS}_{TIC}\right)}_{\mathrm{m}\mathrm{i}\mathrm{n}}$ | ${\left({RS}_{{OCC}_{\mathrm{i}}}\right)}_{\mathrm{a}\mathrm{v}}$ or ${\left({RS}_{TIC}\right)}_{\mathrm{a}\mathrm{v}}$ | ${\left({RS}_{{OCC}_{\mathrm{i}}}\right)}_{\mathrm{m}\mathrm{a}\mathrm{x}}$ or ${\left({RS}_{TIC}\right)}_{\mathrm{m}\mathrm{a}\mathrm{x}}$ | |

Initial fuels inventory | R | $\mathrm{I}\mathrm{F}\mathrm{I}$ | 7.0 | 0.0 | 0.0 | 0.0 |

Other costs (transmission, owner’s, etc.) | T | $\mathrm{O}\mathrm{C}$ | 10.0 | 100.0 | 100.0 | 100.0 |

Land and land rights | R + T | $\mathrm{L}\mathrm{L}\mathrm{R}$ | 0(~0) | 100.0 | 100.0 | 100.0 |

Structure and improvements | R | $\mathrm{S}\&\mathrm{I}$ | 15.0 | 0.0 | 12.0 | 24.0 |

Reactor plant equipment | R | $\mathrm{R}\mathrm{P}\mathrm{E}$ | 18.0 | 0.0 | 0.5 | 1.0 |

Turbine plant equipment | T | $\mathrm{T}\mathrm{P}\mathrm{E}$ | 15.0 | 0.0 | 49.5 | 99.0 |

Electric plant equipment | T | $\mathrm{E}\mathrm{P}\mathrm{E}$ | 5.0 | 42.0 | 60.0 | 78.0 |

Miscellaneous plant equipment | R + T | $\mathrm{M}\mathrm{P}\mathrm{E}$ | 2.0 | 6.0 | 48.5 | 91.0 |

Main condenser and heat rejection system | T | $\mathrm{M}\mathrm{C}\mathrm{H}\mathrm{R}$ | 3.0 | 0.0 | 50.0 | 100.0 |

Total indirect costs | R + T | $\mathrm{T}\mathrm{I}\mathrm{C}$ | 25.0 | 16.0 | 27.5 | 39.0 |

Parameter | Symbol | Value (GF = Greenfield, RE = Repowered) | References |
---|---|---|---|

Lifetime | |||

Construction time, years | CT | 4 | [15] |

Time operational in year, hours | τ_{a} | 7884 | [16] |

Total operation time assumed for the NPV analysis, years | TOT | 50 | [17] |

Capital costs | |||

Unit overnight capital cost (GF investment type), €/kW | uOCC_{GF} | 4000 | [15] |

Variable O&M costs | |||

Refuelling costs, €/MWh | uVOMC(RC) | 7 | [18,19] |

Spent nuclear fuel costs, €/MWh | uVOMC(SFC) | 5 | [20,21] |

Electricity average price, €/MWh | ${C}_{\mathrm{e}\mathrm{l}}$ | 85 | * |

Non-fuel and non-emission costs for turbine island, €/MWh | uVOMC(nnTI) | 1.50 | * |

Fixed O&M costs, €/MW/y | uFOMC | 100,000 (GF)/104,000 (RET) | [15] |

Turbine island, €/MW/y | uFOMC(TI) | 16,000 (GF)/20,000 (RET) | * |

Nuclear Island, €/MW/y | uFOMC(NI) | 84,000 | [15] |

Others | |||

Discount rate, % | $r$ | 6 | * |

Tax rate, % | ${r}_{\mathrm{t}}$ | 19 | * |

Case | |||||
---|---|---|---|---|---|

GF | A | B | C | D | |

NPV, M€ | 1117.75 | 1062.61 | 1096.96 | 1103.12 | 1328.69 |

NPVR, M€ | 0.997 | 1.556 | 1.587 | 1.588 | 1.759 |

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## Share and Cite

**MDPI and ACS Style**

Łukowicz, H.; Bartela, Ł.; Gładysz, P.; Qvist, S. Repowering a Coal Power Plant Steam Cycle Using Modular Light-Water Reactor Technology. *Energies* **2023**, *16*, 3083.
https://doi.org/10.3390/en16073083

**AMA Style**

Łukowicz H, Bartela Ł, Gładysz P, Qvist S. Repowering a Coal Power Plant Steam Cycle Using Modular Light-Water Reactor Technology. *Energies*. 2023; 16(7):3083.
https://doi.org/10.3390/en16073083

**Chicago/Turabian Style**

Łukowicz, Henryk, Łukasz Bartela, Paweł Gładysz, and Staffan Qvist. 2023. "Repowering a Coal Power Plant Steam Cycle Using Modular Light-Water Reactor Technology" *Energies* 16, no. 7: 3083.
https://doi.org/10.3390/en16073083