WO2024160360A1

WO2024160360A1 - A steam turbine, a power plant and a small modular reactor comprising the turbine and a method of manufacturing or servicing of said turbine

Info

Publication number: WO2024160360A1
Application number: PCT/EP2023/052342
Authority: WO
Inventors: Ivan Mcbean
Original assignee: General Electric Technology GmbH
Current assignee: GE Vernova GmbH
Priority date: 2023-01-31
Filing date: 2023-01-31
Publication date: 2024-08-08
Anticipated expiration: 2025-07-31
Also published as: TW202432945A; EP4630656A1

Abstract

There is provided a reaction blade stage for a steam turbine, wherein the reaction blade stage has a ratio of a blade profile chord length of the fixed blades to a blade profile chord length of the moving blades equal to 1.5 – 2.5 and the reaction blade stage is located on and / or after the Wilson point of the steam turbine.

Description

A STEAM TURBINE, A POWER PLANT AND A SMALL MODULAR REACTOR COMPRISING THE TURBINE AND A METHOD OF MANUFACTURING OR SERVICING OF SAID TURBINE Technical field The invention relates to a steam turbine and, more specifically, to a steam turbine for application in power plants. Said steam turbine includes a reaction blade stage that increases efficiency of the steam turbine by addressing droplet behaviour. Aspects of the invention include manufacturing and servicing of steam turbines, as well as power plants and small modular reactors including said steam turbine. Background Achieving higher efficiency of steam turbines is a long-lasting aim of all manufacturers, upgrade providers and users of steam turbines. For application in energy production, this is because higher efficiency of steam turbines is triggering higher efficiency of power plants including said steam turbines. Other applications of steam turbines are also benefiting from higher efficiencies of steam turbines. Efficiency is especially decreased by the effects of condensing steam and presence of condensate, also known as wet steam. Additionally, said wet steam is responsible for degradation of steam turbines. The degradation in time also leads to decrease of efficiency. It follows that there is a need to increase efficiency and, at the same time, to decrease degradation of steam turbines. The efficiency of steam turbines is decreased by losses. There are various categories of losses, e.g., losses due to aerodynamic phenomena, including over shroud leakage losses from water leaks at the top or bottom of a steam turbine blade, blade profile losses etc. Document JP5936992B2 aims at increasing efficiency by dealing with supersaturation losses in steam turbines. Said supersaturated losses are due to droplet nucleation following the transitioning from supersaturated steam to saturated steam. This document invokes chord length, but, as it will be explained in detail in the description, it is not changing said chord length of blades to achieve higher efficiency. In general, the chord length relates to the distance between root and tip of a steam turbine blade. However, this document proposes to change width at the central portion of a steam turbine blade for the last three stages in a given section of a steam turbine. This modification suppresses supersaturated losses and thus aims at higher efficiency. There is no disclosure therein of reduction of degradation of steam turbines. Degradation of different parts of a steam turbine creates different problems for power plant owners and for servicing teams. It is well-known that servicing of stators or, in general, fixed blades is simpler and less time-consuming when compared to moving blades and rotors. This originates from the way how fixed blades or stators including fixed blades are made. At the same time, manufacturing or servicing rotors with moving blades is complex due to the way how strongly moving blades have to be connected to the rotors. Prolonged servicing creates a problem with sustaining of continuity of energy production by power plants and there is interest in sustaining continuity of energy production by power plants. In view of this, the aim is to further increase efficiency of steam turbines while decreasing degradation of steam turbines. Additionally, there is a need to have steam turbines that are durable and thus which are ensuring more sustainable continuity of energy production by power plants including said steam turbines. A further aim is to have an easy-to-service steam turbine. Summary The invention disclosed herein provides a further increase of efficiency and, at the same time, decreases degradation of steam turbines. Additionally, steam turbines according to the invention are easy-to-service. The principles of the invention will be disclosed below and explained. It should be noted that any explanations are provided for a better understanding of the invention and should not be understood as exhaustive or limiting to the invention. As mentioned earlier, formation of water droplets of various sizes due to changes of pressure and/or temperature can affect efficiency of steam turbines and contributes to degradation of steam turbines. An improved efficiency of the invention is achieved by a specific and surprising change of the deposition and size of water droplets within the steam turbine, which increases the efficiency according to the invention. In general, the invention limits the interaction between the moving blades and water droplets such that smaller efficiency losses are observed on the moving blades. Due to the smaller losses, the efficiency is higher for steam turbines according to the invention when compared to steam turbines not including the invention. At the same time, the way how the interaction is modulated by the invention decreases degradation of the steam turbine originating from droplets and film formation on blades of the steam turbine. According to a first aspect of the invention, a steam turbine including at least one steam turbine section is provided. The steam turbine section can be selected from a group including a high-pressure section, a medium-pressure section, and a low- pressure section. The medium-pressure section is also known as an intermediate- pressure section. Parameters of said sections are known in the field of steam turbines and thus no further details are needed here. Embodiments of the invention include combinations of any, some or all of high-pressure, medium-pressure and low-pressure sections in the steam turbine according to the invention. Said at least one steam turbine section comprises a plurality of blade stages and each blade stage includes a row of fixed blades and an adjacent row of moving blades that is downstream of the row of fixed blades. The term “downstream” refers to a general flow of steam and thus steam flows from the row of fixed blades to said row of moving blades. A skilled person understands that in steam turbines the interaction between a row of fixed blades and an adjacent row of moving blades is responsible for inducing rotation of steam turbines and, in application in power plants, ultimately for energy production. It should be noted that the term “stage” (herein also referred to as “blade stage”) has also an established meaning within the field of steam turbine engineering and, hence, does not require further explanations. The same applies for “fixed blades” and “moving blades”. At least one blade stage of the plurality of blade stages is located on or after the Wilson point of the steam turbine. The Wilson point is the point of the primary onset of spontaneous condensation along a path of steam within a steam turbine. In other words, on and after the location of the Wilson point in the steam turbine we observe droplet formation within the steam turbine (wet steam). The path of steam includes trajectories of individual water particles (droplets) as they travel through the turbine. The Wilson point is a known term by the skilled person and the location of the Wilson point can be determined by using numerical methods or through measurements for a given design of a steam turbine. Also, the Wilson point locations can be selected by a specific design of a steam turbine. The purpose of location on and / or after the Wilson point is that the invention affects droplets and droplets are observed on and after the Wilson point location within the steam turbine. At the same time, there is nothing that prohibits from placing said at least one blade stage according to the invention before the location of the Wilson. However, this configuration will not improve efficiency as explain herein. Said at least one blade stage is a reaction blade stage that has a ratio of a fixed blades profile chord length to a moving blades profile chord length from 1.5 to 2.5. The term “profile chord length” is well-known and describes the length (or a distance) between the leading edge of an airfoil profile and the trailing edge. It should be noted that the profile chord length can be selected for each blade individually. Typical practice is to have a single (identical or similar) profile chord length for all blades, i.e., for the fixed blades and for the moving blades. In the known designs, droplets are deposited and form a film both on the fixed blades and the moving blades. The moving blades centrifuge the droplets (or the film created by the droplets) such that the droplets/film are removed from the flow, for example, by depositing on a steam turbine casing. One explanation of increased efficiency by the invention is that the profile chord length according to the invention together with reaction technology, among others, affect this deposition by decreasing deposition of droplets on the fixed blade. The decrease of film on the fixed blade leads to a decrease in large droplets detaching from the fixed blade and subsequently hitting and slowing down the moving blade. Tests of the invention revealed that although certain losses (e.g., aerodynamic) are increased, the blade braking losses are decreased greatly and as a result the efficiency of the steam turbine according to the invention is higher than for a steam turbine with a standard reaction blade layout. Another non-binding explanation for the observed increase of efficiency is that the invention has increased droplet deposition on the moving blade. These droplets form a film, which is centrifuged to the casing, then removed from the flow path, leading to lower wetness induced losses in downstream stages (due to a lower droplet number, lower average droplet size, and / or lower wetness fraction). Reaction also known as the stage degree of reaction or as the stage reaction is a parameter known to the skilled person and used in the field of steam turbine engineering. It relates to angles at which steam is leaving the fixed blades and the moving blades. Irrespectively of the way how you define the stage reaction, it defines a certain design of a blade stage and thus describes configuration of blades in the steam turbine. It follows that the skilled person understands how to make a blade stage or a steam turbine with a given stage reaction degree. Due to the smaller number of droplets shed from the fixed blade (due to decrease droplet deposition on the fixed blade), erosion damage on the moving blades is reduced. Degradation of steam turbine leads to service interruption (due to required repairs) and decreased energy production due to machine downtime and reduced efficiency. It follows that the invention allows for more sustainable energy production by power plants including a steam turbine according to the invention. Alternatively or additionally, the invention prolongs the lifetime of a steam turbine. The highest efficiency of a steam turbine is achieved, where all of those blade stages located on and after the Wilson point of the steam turbine are reaction blade stages that have a ratio of a fixed blades profile chord length to a moving blades profile chord length from 1.5 to 2.5. The best results were obtained for the chord length 1.75 to 2.25 with the stage reaction from 40-45% to 55-60%. Said steam turbine section according to the invention can be selected from a high- pressure section, a medium-pressure section or a low-pressure section. Since the invention can be realized in all types of sections of steam turbines, the invention is versatile. In further embodiments, the steam turbine can include various numbers and types of sections. In one embodiment, the steam turbine can include two said steam turbine sections with one high-pressure section and one low-pressure section. In another embodiment, the steam turbine includes three said steam turbine sections: a high- pressure section, a medium-pressure section, and a low-pressure section. In other words, all known configurations of steam turbines can be realized with the invention. Universality of the invention is one of its advantages. A combination of sections including the invention can further increase the efficiency of the steam turbine. The increase of efficiency can include synergetic effects. This is because the invention affects the size of droplets which are travelling through all sections of steam turbine. Alternatively or additionally, prevention from degradation is not a linear combination of sections according to the invention but a synergistic combination of effects provided by the invention. A small modular reactor including the steam turbine according to embodiments of the invention is another aspect of the invention. Application of the steam turbine according to the invention in small modular reactors (SMRs) is relevant for efficiency of these limited-in-size reactors. Also, more durable steam turbines according to the invention will bring more sustainability to energy production of SMRs. Another aspect of the invention pertains to a power plant. The power plant can include a fossil power plant, a combined cycle power plant, a renewable energy power plant, a waste-to-energy power plant, and a nuclear power plant. Additionally, the steam turbine of the embodiments of the invention can be realized as an industrial steam turbine. The steam turbine can be used as an upgrade to an existing fleet of fossil power plants or as part of any remaining endeavours to build new fossil power plants. Higher efficiency for fossil power plants means that less coal is needed to produce the same amount of energy. Therefore, a steam turbine according to the embodiments of the invention decreases the environmental impact of any fossil power plant. The steam turbine according to the embodiments of the invention can be used in a cycle with a gas turbine, i.e., at a combined cycle power plant. Similar benefits are for the combined cycle power plant as for the fossil power plant. The renewable energy power plant can include a steam turbine according to the invention. As the result, said power plants are able to reach the efficiency expected to meet its power producing expectations. Higher efficiency of the renewable energy power plant will allow it to maximize the usage of, for example, the time when the sun operates. Embodiments of the invention will allow nuclear power plants to maximize the usage of their nuclear sources. It should be noted that the invention can be used on the largest in the world steam turbines such as half-speed units, e.g., implementing Arabelle product line steam turbines. Increasing the efficiency of already existing fleet of nuclear power plants is beneficial for any power plant owner as it allows to obtain higher energy production without the need to build additional nuclear power plants or without the need to largely modify nuclear power plants. This allows to significantly lower the time that is needed to produce more energy from nuclear power plants, as a typical way to increase power production includes building new power plants or adding new units to existing ones and that takes years to be completed. All types of power plants will benefit from sustaining stable energy production provided by steam turbines according to embodiments of the invention. Another aspect of the invention relates to a use of a steam turbine of the embodiments of the invention for increasing power production of a power plant. Said power plant can be any known or new-build power plant. Additionally, the power plant can be a fossil power plant, a combined cycle power plant, a renewable energy power plant or a nuclear power plant. It is noted that increase of efficiency, even at the level of up to a few percent by the embodiments of the invention (from 0.1%, 0.2%, 0.3%, 0.4%, up to and including 0.5% or more for the most efficient embodiments of the invention) is translated to a significant increase in power production by a power plant. A typical increase would be 0.5% and higher values are expected for higher steam wetness. For any power plant, an increase of power production by a fraction or even by a few percent translates to enormous benefits. Said benefits may include better usage of resources (e.g., coal, nuclear source, sun light), more stable production of energy at the time of increase in demand for electrical power or production of less wastes by a power plant. Another aspect of the invention includes a method of manufacturing or servicing of a steam turbine. In embodiments, the steam turbine comprises a plurality of blade stages, wherein said at least one steam turbine section comprises at least one blade stage, each blade stage includes a row of fixed blades and an adjacent row of moving blades that is downstream of the row of fixed blades. In embodiments, the method of manufacturing includes providing at least one blade stage of the plurality of blade stages located on or after the Wilson point of the steam turbine with a ratio of a fixed blades profile chord length to a moving blades profile chord length from 1.5 to 2.5, and wherein said at least one blade stage is a reaction blade stage. An embodiment of this method includes providing all blade stages of the plurality of blade stages located on and after the Wilson point of the steam turbine with a ratio of a fixed blades profile chord length to a moving blades profile chord length from 1.5 to 2.5 and wherein said all blade stages are reaction blade stages. While manufacturing relates to providing new steam turbines, servicing relates to improving or maintaining existing steam turbines. The invention can be implemented easily to an existing steam turbine as a servicing method by replacing the fixed blades only. This benefit originates from the differences in servicing of fixed blades and moving blades. It is well-known that the moving blades have to be connected with a rotor firmly due to tensions that the rotor blades suffer in operation. At the same time, the fixed blades can be replaced together with a stator, casing, i.e., without the need to disconnect them from the casing or the stator. Additionally, the connection between the fixed blades and the stator or casing is not as strong when compared to the connection used for the moving blades. It follows that both installation and replacement of the rotor blades is technologically challenging and may even lead to damaging of rotor and / or moving blades. This creates increase of wastes and a need to manufacture new parts. The technological challenge of servicing of the moving blades transfers to the time that is needed for servicing of the rotor blades and to the impact thereof on the time of an outage. The outage causes lack of energy production for a power plant that includes a steam turbine under service. Therefore, the longer servicing of the steam turbine takes time, the longer the outage lasts. The invention by affecting only the fixed blades allows to increase efficiency faster when compared to servicing involving replacement of moving blades or both moving and fixed blades. It will be appreciated that the use of the terms “first” and “second”, and the like, in this patent specification is merely intended to help distinguish between similar features, and is not intended to indicate the relative importance of one feature over another feature, unless otherwise specified. Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in this disclosure, and the claims and/or the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and all features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner. Brief description of figures Embodiments including preferred embodiments of the invention will now be described, by way of non-limiting examples, with reference to the accompanying drawings in which: Fig.1 shows conventional reaction blade stages of a steam turbine; Fig.2 shows reaction blade stages of a steam turbine according to an embodiment of the invention; Fig. 3 (a) shows droplet distribution and size for a blade stage of a typical steam turbine and Fig. 3 (b) shows a droplet distribution and size for a blade stage of a steam turbine according to an embodiment of the invention; Fig. 4 shows a comparison of deposition of droplets on the fixed blades between a typical design of a steam turbine and a steam turbine according to the invention and Fig. 5 shows a comparison of deposition of droplets on the moving blades between a typical design of a steam turbine and a steam turbine according to the invention; and Fig. 6 shows a comparison of losses between a typical design of a steam turbine and a steam turbine according to an embodiment of the invention. Detailed description The following non-limiting embodiments of the invention are described with reference to reaction blade stages in steam turbines. In conventional reaction blade stages as shown in Fig. 1, the blades of the stator 20 and rotor 22 have similar blade chord lengths for cost per performance reasons. As a result steam droplets are evenly deposited on the fixed blades 20 and moving blades 22, which has an impact on the wetness loss and efficiency of the reaction blade stage. A steam turbine according to an embodiment of the invention is shown in Fig. 2. In this embodiment, the steam turbine comprises a plurality of reaction blade stages. Each reaction blade stage comprises a row of fixed blades and an adjacent row of moving blades that is downstream of the row of fixed blades. Said row of fixed blades can be included in a stator or in a casing for steam turbine. The adjacent row of moving blades is included in a rotor. In use, steam flows through the rows of fixed blades 30 and the rows of moving blades 30 so as to enable each reaction blade stage to convert thermal energy from the steam into mechanical energy via a rotating output shaft of the steam turbine. A ratio R_chord of a fixed blades profile chord length s_{fixed blade} to a moving blades profile chord length smoving blade is defined by Equation 1. ^ ^{^} ^_^^^ௗ = ^{^^^^^ ್^ೌ^^} ^_{^^ೡ^^^ ್^ೌ^^} (1) For example,

the fixed blades and the moving blades may be in the range of 20mm and 400mm, blade stagger angles of the fixed blades and the moving blades may be in the range of 45° and 65°, and aspect ratios of the fixed blades and the rotor blades may be in the range of 1 and 7. An aspect ratio of the fixed blades is a ratio of a blade height h_{fixed blade} and a blade profile chord length s_{fixed blade} of the fixed blades. An aspect ratio of the rotor is a ratio of a blade height hmoving blade and a blade profile chord length smoving blade of the rotor. In use, the moving blades 32 of the rotor tend to centrifuge the resulting water film due to deposition of steam droplets on the moving blades 32, and this film is removed at the casing of the steam turbine. Large water droplets transported from the fixed blades 30 to the moving blades 32 have a detrimental effect on the rotation of the moving blades 32 by increasing braking losses in the rotor. The inventors have found that a steam turbine with reduced loss is achieved by setting the value of Rchord for a reaction blade stage in the range of 1.5 and 2.5. Preferably, this value of Rchord is applied for all reaction blade stages. In embodiments, by increasing the blade profile chord length sfixed blade of the fixed blades, the deposition of steam droplets on the fixed blades 30 can be reduced, which has the effect of reducing the amount of large water droplets shedding from the fixed blades trailing edge 30 to the moving blades leading edge 32 and thereby reducing braking losses in the rotor due to the impact of droplets on the moving blades 32. Furthermore, the reduction of droplet deposition reduces surface deterioration of the moving blades 30, 32. Also, by decreasing the blade profile chord length smoving blade of the rotor, the secondary flow losses in the rotor can be reduced. Fig. 3 shows droplet deposition in (a) a conventional reaction blade stage and (b) a reaction blade stage of the invention. The flow paths of the droplets are graphically shown as flow lines, each of which extends through a number of spaced apart circles. It can be seen from the flow lines in Fig. 3 that the amount of droplet deposition on the fixed blades of the reaction blade stage of the invention are reduced in comparison to the amount of droplet deposition on the fixed blades of the conventional reaction blade stage. Fig. 4 and Fig. 5 are comparing the results obtained for six blades stages of a steam turbine. Fig. 4 compares the relative amounts of droplet deposition on the fixed blades of the stator for the conventional reaction blade stage and the reaction blade stage of the invention. The left hand side of the graph compares the amount 34 of small droplet (e.g., size of 2*10^-6 m) deposition for the conventional reaction blade stage against the amount 36 of small droplet deposition for the reaction blade stage of the invention. The values are changing from about 20% to 15%. The right hand side of the graph compares the amount 38 of large droplet (e.g., size of 1*10^-5 m) deposition for the conventional reaction blade stage against the amount 40 of large droplet deposition for the reaction blade stage of the invention. The values are changing from about 97% to 70%. In embodiments, the average size of the large droplets is approximately an order of magnitude larger than the average size of the small droplets. It can be seen from Fig.4 that a 25% decrease in droplet deposition on the fixed blades is observed for the reaction blade stage of the invention for small and large droplets, in comparison to the conventional reaction blade stage. Fig. 5 compares the relative amounts of droplet deposition on the moving blades of the rotor for the conventional reaction blade stage and the reaction blade stage of the invention. The size of small and big droplets is the same as for the embodiment of Fig. 4, respectively. The left hand side of the graph compares the amount 42 of small droplet deposition for the conventional reaction blade stage against the amount 44 of small droplet deposition for the reaction blade stage of the invention. The values are changing from about 9% to 13%. The right hand side of the graph compares the amount 46 of large droplet deposition for the conventional reaction blade stage against the amount 48 of large droplet deposition for the reaction blade stage of the invention. The values are changing from about 40% to 53%. It can be seen from Fig. 5 that increase in small droplet and large droplet deposition on the moving blades is observed for the reaction blade stage of the invention in comparison to the conventional reaction blade stage. This increase in deposition increases the amount of film centrifuged to the outer flow path region, where it can be removed by water extraction features. This reduces the steam wetness content and reduces losses in the stages downstream, further increasing turbine efficiency. Fig. 6 compares the aerodynamic losses, other wetness losses and braking losses of consecutive conventional reaction turbine blade stages A1, A2, A3 and consecutive reaction blade stages B1, B2, B3 of the invention. In the graph of Fig. 6, the aerodynamic losses, other wetness losses and braking losses are shown in order from left to right for each reaction turbine blade stage. Although the aerodynamic losses for the reaction blade stages B1, B2, B3 of the invention are marginally increased in comparison to the aerodynamic losses for the conventional reaction blade stages A1, A2, A3, the braking losses for the reaction blade stages B1, B2, B3 of the invention are significantly decreased in comparison to the braking losses for the conventional reaction blade stages A1, A2, A3. In other words, the increase in magnitude of the aerodynamic losses is much less than the decrease in magnitude of the braking losses, thus resulting in an overall increase in efficiency. The listing or discussion of an apparently prior-published document or apparently prior- published information in this specification should not necessarily be taken as an acknowledgement that the document or information is part of the state of the art or is common general knowledge. Preferences and options for a given aspect, feature or parameter of the invention should, unless the context indicates otherwise, be regarded as having been disclosed in combination with any and all preferences and options for all other aspects, features and parameters of the invention. The above description of embodiments of the disclosure, including what is described in the Abstract, is not intended to be exhaustive or to limit the disclosed embodiments to what precisely was disclosed. Specific embodiments and examples are described herein for illustrative purposes and modifications are possible as can be appreciated by those skilled in the art. In particular, parts, components, steps and aspects from different embodiments may be combined or suitable for use in other embodiments even though not described in the disclosure or depicted in the figures. It is to be understood that other similar embodiments can be used or modifications and additions can be made to the described embodiments for performing the same, similar, alternative, or substitute function of the disclosed subject matter without deviating therefrom. References to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. The terms “including” and “in which” are used as the plain-English equivalents of the terms “comprising” and “wherein”, respectively. Terms “first”, “second”, “third”, etc. are used merely as labels, and are not intended to impose numerical or positional requirements on their objects. The term “about” is to describe reasonably achievable tolerances for engineering.

Claims

CLAIMS 1. A steam turbine including at least one steam turbine section, wherein said at least one steam turbine section comprises a plurality of blade stages, each blade stage includes a row of fixed blades and an adjacent row of moving blades that is downstream of the row of fixed blades, and wherein at least one blade stage of the plurality of blade stages has a ratio of a fixed blades profile chord length to a moving blades profile chord length from 1.5 to 2.5 and is a reaction blade stage located on or after the Wilson point of the steam turbine.

2. The steam turbine according to claim 1, wherein all blade stages located on and after the Wilson point of the steam turbine are reaction blade stages that have a ratio of a fixed blades profile chord length to a moving blades profile chord length from 1.5 to 2.5.

3. The steam turbine according to any of claims 1-2, wherein the ratio of a fixed blades profile chord length to a moving blades profile chord length is from 1.75 to 2.25.

4. The steam turbine according to any of claims 1-3, wherein the stage reaction for the reaction blade stages is from 40% to 60%.

5. The steam turbine according to claim 4, wherein the stage reaction is from 45% to 55%.

6. The steam turbine according to any one of claims 1-5, wherein said steam turbine section is selected from a group including a high-pressure section, a medium-pressure section, and a low-pressure section.

7. The steam turbine according to any one of claims 1-6, wherein the steam turbine includes two said steam turbine sections, wherein one is a high-pressure section and one is a low-pressure section, or wherein the steam turbine includes three said steam turbine sections wherein one is a high-pressure section, one is a medium-pressure section and one is a low-pressure section.

8. A small modular reactor wherein the small modular reactor includes a steam turbine according to any of claims 1-7.

9. A power plant selected from a group including a fossil power plant, a combined cycle power plant, a renewable energy power plant, a waste-to-energy power plant, and a nuclear power plant, wherein that the power plant includes a steam turbine according to any of claims 1-7.

10. A use of a steam turbine defined in any of claims 1-7 for increasing power production of a power plant or for increasing efficiency of an industrial process or for ensuring sustainable energy production of a power plant.

11. A method of manufacturing or servicing of a steam turbine, wherein the steam turbine comprises at least one steam turbine section, wherein said at least one steam turbine section comprises at least one blade stage, each blade stage includes a row of fixed blades and an adjacent row of moving blades that is downstream of the row of fixed blades, the method includes providing at least one blade stage of the plurality of blade stages located on or after the Wilson point of the steam turbine with a ratio of a fixed blades profile chord length to a moving blades profile chord length from 1.5 to 2.5, and wherein said at least one blade stage is a reaction blade stage, or configuring the row of fixed blades of at least one blade stage of the plurality of blade stages located on or after the Wilson point of the steam turbine to obtain a ratio of a fixed blades profile chord length to a moving blades profile chord length from 1.5 to 2.5 and to make said at least one blade stage a reaction blade stage.

12. The method of manufacturing or servicing of a steam turbine according to claim 11, wherein the method of manufacturing includes providing all blade stages of the plurality of blade stages located on and after the Wilson point of the steam turbine with a ratio of a fixed blades profile chord length to a moving blades profile chord length from 1.5 to 2.5 and wherein said all blade stages are reaction blade stages, or wherein the method of servicing includes configuring rows of fixed blades of all blade stages of the plurality of blade stages located on and after the Wilson point of the steam turbine to obtain a ratio of a fixed blades profile chord length to a moving blades profile chord length from 1.5 to 2.5 and to make said blade stages reaction blade stages.

13. The method of manufacturing or servicing of a steam turbine according to claim 12, wherein the ratio of a fixed blades profile chord length to a moving blades profile chord length is from 1.75 to 2.25.

14. The method of manufacturing or servicing of a steam turbine according to any of claims 11-13, wherein the stage reaction for the reaction blade stages is from 40% to 60%.

15. The method of manufacturing or servicing of a steam turbine according to claim 14, wherein the stage reaction is from 45% to 55%.