Horizontal Steam Generator for a Reactor Plant with a Water-Cooled Water-Moderated Power Reactor and a Reactor Plant with the said Steam Generator

Abstract

This invention relates to electric power industry, and more particularly to horizontal steam generators for nuclear power plants with a water-cooled water-moderated power reactor (VVER) and to reactor plants with a VVER reactor and a horizontal steam generator. A reactor plant with a VVER reactor and a horizontal seam generator, including a nuclear reactor with four circulation loops, each comprising a steam generator with a horizontal bundle of heat-exchange tubes divided into banks by means of inter-tubular tunnels and connected to primary circuit coolant headers inside a cylindrical pressure vessel with elliptical bottoms, a reactor coolant pump, and a primary circuit coolant main circulation pipeline.

Claims

1. A horizontal steam generator for a reactor plant with a water-cooled water-moderated power reactor comprising a cylindrical pressure vessel equipped at least with one feed water supply connection pipe and one steam removal connection pipe, and two elliptical bottoms, internals, primary circuit coolant inlet and outlet headers connected to a heat-exchange tube bundle forming a steam-generator heat-exchange surface, the heat-exchange tube bundle being divided into banks by intertubular tunnels, wherein distance S between the primary circuit coolant header centerlines in the transverse direction of the steam generator pressure vessel has been selected based on the following ratio: $0.4\le \frac{S}{D_{\mathrm{vess}}}\le 0.6,$ where D.sub.vess is the steam generator pressure vessel inner diameter, and steam generator length L.sub.v along the inner surfaces of the elliptical bottoms has been selected based on the following ratio: $L_{\kappa }=D_{\mathrm{head}}+2.Math.\left[\left(\mathrm{ctg}\left(\frac{\alpha }{2}\right)-\frac{1}{\sin \left(\frac{\alpha }{2}\right)}\right).Math.\left(\frac{B_1}{2}+B_2+\left(\frac{\pi .Math.D_{\mathrm{head}}}{4.Math.S_{\mathrm{head}}}-1\right).Math.S_h\right)+\left(\frac{\pi .Math.D_{\mathrm{head}}}{4.Math.S_{\mathrm{head}}}-1\right).Math.S_h.Math.\frac{1}{\sin \left(\frac{\alpha }{2}\right)}+\Delta \right]+\frac{H_{\mathrm{hes}}.Math.{10}^6}{\pi .Math.d.Math.N_{\mathrm{tb}}},$ where: D.sub.head is the coolant header outer diameter in the drilled part, mm, α is the heat-exchange tube central bend angle, deg., B.sub.1 is the width of the heat-exchange tube central intertubular tunnel, mm, B.sub.2 is the width of the heat-exchange tube intertubular tunnel opposite to the coolant header, mm, S.sub.head is the heat-exchange tube circumferential spacing on the outer surface of the coolant header, mm, Sh is the spacing between heat-exchange tubes in the horizontal heat-exchange bundle row, mm, H.sub.hes is the steam generator heat-exchange surface area, m.sup.2, N.sub.tb is the number of steam generator heat-exchange tubes, pcs., d is the outer heat-exchange tube diameter, mm, Δ is the distance from the outer heat-exchange bundle tube to the steam generator bottom inner surface along the longitudinal steam generator axis, in mm, wherein central heat-exchange tube bend angle α and distance Δ have been selected from the following ranges: 90°≦α≦150° and 300≦Δ≦1000 mm.

2. A steam generator according to claim 1, wherein the heat-exchange tube bundle is filled with heat-exchange tubes from bottom upwards evenly with vertical gaps between adjacent tubes not exceeding the vertical spacing of tubes in the bundle.

3. A steam generator according to claim 1, wherein the vertical intertubular tunnel width is between 100 mm and 250 mm.

4. A steam generator according to claim 1, wherein the heat-exchange tube bend at the point of connection to the coolant header shall have a radius of at least 60 mm and, preferably, at least 100 mm.

5. A steam generator according to claim 1, wherein the coolant header drilling area shall exceed the area of the holes for connection of heat-exchange tubes to the same by at least 20%.

6. A reactor plant with a water-cooled water-moderated power reactor and a horizontal seam generator, including a nuclear reactor with four circulation loops, each comprising a steam generator with a horizontal bundle of heat-exchange tubes divided into banks by means of intertubular tunnels and connected to primary circuit coolant headers inside a cylindrical pressure vessel with elliptical bottoms, a reactor coolant pump, and a primary circuit coolant main circulation pipeline, wherein pressure vessel bore D.sub.vess, distance S between the centerlines of the primary circuit coolant headers in the transverse direction and steam generator length L.sub.v along the inner surfaces of the elliptical bottoms have been respectively selected based on the following ratios: $0.148.Math.D+0.637.Math.\sqrt{0.054.Math.D^2+3.142.Math.\frac{N_{\mathrm{tb}}.Math.S_h.Math.S_v}{k}}\le D_{\mathrm{vess}}\le 1.827.Math.H,.Math..Math.0.4\le \frac{S}{D_{\mathrm{vess}}}\le 0.6,.Math.L_{\kappa }=D_{\mathrm{head}}+2.Math.\left[\left(\mathrm{ctg}\left(\frac{\alpha }{2}\right)-\frac{1}{\sin \left(\frac{\alpha }{2}\right)}\right).Math.\left(\frac{B_1}{2}+B_2+\left(\frac{\pi .Math.D_{\mathrm{head}}}{4.Math.S_{\mathrm{head}}}-1\right).Math.S_h\right)+\left(\frac{\pi .Math.D_{\mathrm{head}}}{4.Math.S_{\mathrm{head}}}-1\right).Math.S_h.Math.\frac{1}{\sin \left(\frac{\alpha }{2}\right)}+\Delta \right]+\frac{H_{\mathrm{hes}}.Math.{10}^6}{\pi .Math.d.Math.N_{\mathrm{tb}}},$ where: D is the rated steam generator capacity, t/h, N.sub.tb is the number of steam generator vessel heat-exchange tubes, pcs., Sv, Sh is the spacing between heat-exchange tubes in vertical and horizontal rows of heat-exchange bundle, respectively, mm, k is the arrangement identifier of heat-exchange tube bundle in a bank (k=1 for in-line arrangement and k=2 for staggered arrangement), H is the steam generator vessel tube filling height, mm, D.sub.head is the primary circuit header outer diameter in the drilled area, mm, α is the heat-exchange tube central bend angle, deg., B.sub.1 is the width of the heat-exchange tube central tunnel, mm, B.sub.2 is the width of the heat-exchange tube tunnel opposite to the coolant header, mm, S.sub.head is the heat-exchange tube circumferential spacing on the outer surface of the coolant header, mm, H.sub.hes is the steam generator heat-exchange surface area, m.sup.2, d is the outer heat-exchange tube diameter, mm, Δ is the distance from the outer heat-exchange bundle tube to the steam generator bottom inner surface along the longitudinal steam generator axis, in mm, wherein heat-exchange tube bend angle α and distance Δ have been selected from the following ranges: 90°≦α≦150° and 300 mm≦Δ≦1000 mm.

7. A reactor plant according to claim 6, wherein the steam generator and the reactor coolant pump are connected to the reactor building walls by hydraulic snubbers.

8. A reactor plant according to claim 6, wherein the reactor coolant pump is installed downstream of the steam generator along the primary circuit coolant flow in the circulation loop.

9. A reactor plant according to claim 6, wherein the reactor coolant pump is installed both on the hot leg and the cold leg of the main circulation pipeline in the circulation loop.

10. A reactor plant according to claim 6, wherein two reactor coolant pumps are installed in parallel on the cold leg of the main circulation pipeline.

11. A reactor plant according to claim 6, wherein gate valves are installed on the main circulation pipeline legs.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The invention is illustrated by the following figures.

[0058] FIG. 1 shows a horizontal section of the containment with a reactor plant installed in it.

[0059] FIG. 2 shows a horizontal section of the steam generator pressure vessel.

[0060] FIG. 3 shows a horizontal section detail of the steam generator pressure vessel at the point of heat-exchange tube connection to the primary circuit coolant header.

[0061] FIG. 4 shows a cross-section of the steam generator along the centerline of the primary circuit coolant inlet header.

[0062] FIG. 5 shows the heat-exchange tube staggered arrangement.

[0063] FIG. 6 shows the heat-exchange tube in-line arrangement.

[0064] FIG. 7 shows a reactor plant (RP) primary circuit coolant circulation loop with a reactor coolant pump (RCP) installed on the cold leg of the main circulation pipeline (MCP).

[0065] FIG. 8 shows an RP primary circuit coolant circulation loop with an RCP installed on the MCP cold leg and hot leg.

[0066] FIG. 9 shows an RP primary circuit coolant circulation loop with two RCPs installed on the MCP cold leg.

[0067] FIG. 10 shows an RP primary circuit coolant circulation loop with gate valves installed on the MCP cold leg and hot leg.

DETAILED DESCRIPTION

[0068] The reactor plant equipment, including steam generators, and its safety systems shall be installed in the NPP reactor compartment. The reactor compartment consists of a pressurized part and unpressurized part. The primary circuit equipment and the reactor are typically installed in the pressurized part.

[0069] FIG. 1 shows a horizontal section of containment 1 with a reactor plant installed in it. The containment is designed as a cylinder of prestressed reinforced concrete, its thickness, for instance, for the VVER-1000 project, is 1.2 m, its inner diameter is 45 m and height is 52 m.

[0070] A reactor 2 connected to steam generators 4 by means of a main circulation pipeline (MCP) 3 is located in the central part of the containment 1. Reactor coolant pumps (RCP) 5 are used to pump the primary circuit coolant (pressurized water) from the steam generators 4 to the reactor 2 and back through the MCP. To maintain the pressure and compensate for coolant volume variation during its heating or cooling, pressurizers 6 are additionally applied in the reactor plant. As is shown in FIG. 1, the steam generators 4 occupy a larger area than any other reactor plant equipment in the containment. However, society development requires increased power generation and increased reactor plant power from NPPs and, therefore, increased an heat-exchange surface and dimensions of steam generators, which can hardly be fit in reactor building boxes already at this moment. Further increase of the area and size of containments is uneconomical due to significant increase of the scope and costs of NPP capital construction.

[0071] The claimed invention allows to increase heat transfer intensity, reliably and durability of a steam generator by increasing the number of heat-exchange tubes in its pressure vessel, which allows to improve performance of the reactor plant without any considerable increase in dimensions, making it possible to fit steam generators in containment boxes of the specified size.

[0072] The claimed horizontal steam generator 4 for a reactor plant with a VVER reactor comprises a cylindrical vessel 7 equipped with at least a feed water supply connection pipe 8 and a steam removal connection pipe 9, two elliptical bottoms 10, internals, an inlet header 11 and an outlet header 12 of the primary circuit coolant connected to a heat-exchange tube bundle 13 making up a heat-exchange surface of the steam generator, wherein the heat-exchange tube bundle is divided into banks 14 and 15 by means of intertubular tunnels 16. To solve the task at hand, distance S (FIG. 2) between the centerlines of the headers 11 and 12 of the primary circuit coolant in the transverse direction of the steam generator pressure vessel 7 has been selected based on the following ratio:

[00004]$0.4\le \frac{S}{D_{\mathrm{vess}}}\le 0.6,$

where D.sub.vess is the steam generator pressure vessel inner diameter, and steam generator length L.sub.v measured along the inner surfaces of the elliptical bottoms has been selected based on the following ratio:

[00005]$L_{\kappa }=D_{\mathrm{head}}+2.Math.\left[\left(\mathrm{ctg}\left(\frac{\alpha }{2}\right)-\frac{1}{\sin \left(\frac{\alpha }{2}\right)}\right).Math.\left(\frac{B_1}{2}+B_2+\left(\frac{\pi .Math.D_{\mathrm{head}}}{4.Math.S_{\mathrm{head}}}-1\right).Math.S_h\right)+\left(\frac{\pi .Math.D_{\mathrm{head}}}{4.Math.S_{\mathrm{head}}}-1\right).Math.S_h.Math.\frac{1}{\sin \left(\frac{\alpha }{2}\right)}+\Delta \right]+\frac{H_{\mathrm{hes}}.Math.{10}^6}{\pi .Math.d.Math.N_{\mathrm{tb}}},$

[0073] where: D.sub.head is the coolant header outer diameter in the drilled part, mm,

α is the heat-exchange tube central bend angle, deg.,

[0074] B.sub.1 is the width of the heat-exchange tube central intertubular tunnel, mm,

[0075] B.sub.2 is the width of the heat-exchange tube intertubular tunnel opposite to the coolant header, mm,

[0076] S.sub.head is the heat-exchange tube circumferential spacing on the outer surface of the coolant header, mm. The above spacing is measured as a distance from the center of one heat-exchange tube to the center of its adjacent heat-exchange tube in a horizontal row on the outer surface of the coolant header.

[0077] Sh is the spacing between heat-exchange tubes in the horizontal heat-exchange bundle row, mm. The above spacing is measured as a distance from the center of one heat-exchange tube to the center of its adjacent heat-exchange tube in a horizontal row on the outer surface of the coolant header as is shown in FIGS. 5 and 6.

[0078] H.sub.hes is the steam generator heat-exchange surface area, m.sup.2. The steam generator heat-exchange surface area is measured as a sum total of surface areas of the heat-exchange bundle tubes.

[0079] N.sub.tb is the number of steam generator heat-exchange tubes, pcs.

[0080] d is the outer heat-exchange tube diameter, mm.

[0081] Δ is the distance from the outer heat-exchange bundle tube 17 to the steam generator bottom 10 inner surface along the longitudinal steam generator axis, in mm, wherein central heat-exchange tube bend angle α and distance 4 have been selected from the following ranges: 90°≦α≦150° and 300≦Δ≦1000 mm.

[0082] According to the claimed invention, the steam generator heat-exchange tubes bundle 13 is filled with heat-exchange tubes from bottom upwards continuously with vertical gaps b between adjacent tubes not exceeding the vertical spacing of tubes in the bundle, as is shown in FIGS. 5 and 6. Horizontal heat-exchange tubes are inserted in holes in vertical headers 11 and 12 of the primary circuit coolant. As is shown in FIG. 3, at the point of connection to the coolant header, the heat-exchange tube bend shall have radius Rh of at least 60 mm and, preferably, at least 100 mm.

[0083] The steam generator may include at least the following internals: a feed water supply and distribution device 18 located above the heat-exchange tube bundle 13, an emergency feed water supply and distribution device 19 located in the steam space, device 20 for chemical reagent supply during steam generator flushing, a submerged perforated sheet 21 and an overhead perforated sheet 22.

[0084] During steam generator 4 operation, the primary circuit coolant is supplied from the reactor 2 to the steam generator inlet header 11, distributed among the heat-exchange bundle 13 tubes and flows through the same to the outlet header 12 transferring its heat to the boiler water, i.e. the secondary circuit coolant (medium) through the heat-exchange surface wall. Feed water is supplied to the steam generator through the connection pipe 8 and the feed water supply and distribution device 18 connected to the same, making up the boiler water in the steam generator, and is heated up by mixing with the steam-water mixture in it. Water heated up to saturation is drawn into the steam generator circulation circuit (secondary circuit). The secondary circuit coolant boils on the steam generator heat-exchange surface and moves up the circulation circuit riser sections. To separate water from steam in the steam generator, a single-stage gravitation settling separation is applied. Steam is removed from the steam generator through steam tubes 9 in the upper part of the vessel 7.

[0085] Steam leaving the heat-exchange bundle 13 is compensated for by means of water downward motion in the intertubular tunnels 16, 23 along the tube bank length, and in the gap between the steam generator vessel and tube bundle.

[0086] The empirical formula ratio proposed for calculation of the steam generator length Lv is based on the process requirements for the heat-exchange surface tube bend near the steam generator bottoms. The heat-exchange bundle tubes shall be U-shaped in three bends. The angle of the central bend is between 90° and 150°, and the distance between the heat-exchange bundle outer tube and the inner bottom surface between 300 mm and 1000 mm, which is essential in terms of the process and technical and economic considerations. The preferable heat-exchange tube central bend angle is 120°.

[0087] The formula 0.4≦S/D.sub.vess≦0.6 describes a steam generator design with heat-exchange tube banks of almost the same width. Provided that heat-exchange tube banks are equal in width, when S/D.sub.vess=0.5, the largest number of heat-exchange tubes can be fit in the steam generator, other things being equal, which reduces steam generator pressure vessel specific amount of metal per structure.

[0088] A steam generator may be assembled with a distance between the headers in the transverse direction outside the specified range, but the number of tubes in such steam generator will be less than required for its efficient operation due to the fact that the inner space of the vessel is not effectively used. Namely, if distance S between the centerlines of the coolant headers in the transverse direction is S≦0.4.Math.D.sub.vess, a considerable space in the central part of the steam generator adjacent to the longitudinal section plane in the heat-exchange bundle area will remain unfilled with heat-exchange tubes due to the reason described below. To insert heat-exchange tubes in the coolant header holes, they shall have specified bend radius Rh (FIG. 3), and the length of a straight section at the end shall exceed the depth of a hole in the header wall the tube is inserted in. In addition, heat-exchange tube bend radii shall be at least 60 mm, and preferably at least 100 mm to be inserted in the header holes.

[0089] If distance S between the centerlines of the coolant headers in the transverse direction is S≧0.6.Math.D.sub.vess, a considerable space in the peripheral part of the steam generator adjacent to the vessel side walls in the area of the heat-exchange bundle will remain unfilled with heat-exchange tubes for the above reason, as to insert heat-exchange tubes in the coolant header holes they shall have the specified bend radius, and the length of a straight section at the end shall exceed the depth of the hole in the header wall the tube is inserted in.

[0090] Manufacture of a steam generator with its vessel inner diameter D.sub.vess, distance S between the centerlines of the coolant headers in the transverse direction and length Lv (along the inner surfaces of the elliptical bottoms) selected allows to fit the largest number of heat-exchange tubes in the steam generator pressure vessel of the selected size providing their secure mounting, while obtaining steam with the required water content in the vessel of the minimum diameter, and meeting the requirements to the ease of manufacturing of U-shaped heat-exchange tubes. Steam generator dimensions D.sub.vess are Lv are considering its installation as part of a reactor plant in containment boxes.

[0091] The reactor plant comprising the claimed steam generator is shown in FIG. 1. It comprises a nuclear reactor 2 with four circulation loops, each comprising a steam generator 4 with a horizontal bundle 13 of heat-exchange tubes divided into banks 14 and 15 by intertubular tunnels 16 and connected to primary circuit coolant headers 11 and 12 inside a cylindrical vessel 7 with elliptical bottoms 10, a reactor coolant pump 5, and a main circulation pipeline 3 of the primary circuit coolant, wherein vessel 7 inner diameter D.sub.vess, distance S between the centerlines of the primary circuit coolant headers 11 and 12 in the transverse direction, and steam generator length Lv along the inner surfaces of the elliptical bottoms 10 are selected, respectively, by the following ratios:

[00006]$0.148.Math.D+0.637.Math.\sqrt{0.054.Math.D^2+3.142.Math.\frac{N_{\mathrm{tb}}.Math.S_h.Math.S_v}{k}}\le D_{\mathrm{vess}}\le 1.827.Math.H,.Math..Math.0.4\le \frac{S}{D_{\mathrm{vess}}}\le 0.6,.Math.L_{\kappa }=D_{\mathrm{head}}+2.Math.\left[\left(\mathrm{ctg}\left(\frac{\alpha }{2}\right)-\frac{1}{\sin \left(\frac{\alpha }{2}\right)}\right).Math.\left(\frac{B_1}{2}+B_2+\left(\frac{\pi .Math.D_{\mathrm{head}}}{4.Math.S_{\mathrm{head}}}-1\right).Math.S_h\right)+\left(\frac{\pi .Math.D_{\mathrm{head}}}{4.Math.S_{\mathrm{head}}}-1\right).Math.S_h.Math.\frac{1}{\sin \left(\frac{\alpha }{2}\right)}+\Delta \right]+\frac{H_{\mathrm{hes}}.Math.{10}^6}{\pi .Math.d.Math.N_{\mathrm{tb}}},$

[0092] where: D is the rated steam generator capacity, t/h,

[0093] N.sub.tb is the number of steam generator vessel heat-exchange tubes, pcs.,

[0094] Sv, Sh is the spacing between heat-exchange tubes in vertical and horizontal rows of heat-exchange bundle, respectively, mm, as is shown in FIGS. 5 and 6,

[0095] k is the arrangement identifier of heat-exchange tube bundle in a bank (k=1 for in-line arrangement and k=2 for staggered arrangement),

[0096] H is the steam generator vessel tube filling height, mm, as is shown in FIG. 4,

[0097] D.sub.head is the primary circuit header outer diameter in the drilled area, mm,

[0098] α is the heat-exchange tube central bend angle, deg.,

[0099] B.sub.1 is the width of the heat-exchange tube central tunnel, mm,

[0100] B.sub.2 is the width of the heat-exchange tube tunnel opposite to the coolant header, mm,

[0101] S.sub.head is the heat-exchange tube circumferential spacing on the outer surface of the coolant header, mm,

[0102] H.sub.hes is the steam generator heat-exchange surface area, m.sup.2,

[0103] d is the outer heat-exchange tube diameter, mm,

[0104] Δ is the distance from the outer heat-exchange bundle tube to the steam generator bottom inner surface along the longitudinal steam generator axis, wherein heat-exchange tube bend angle α and distance Δ have been selected from the following ranges:

[0105] 90°≦α≦150° and 300 mm≦Δ≦1000 mm.

[0106] To improve the seismic stability, the steam generator and reactor coolant pump may be attached to the reactor building walls by means of hydraulic snubbers 24.

[0107] FIGS. 7-9 show arrangement options of the proposed reactor plant as exemplified by one of the four circulation loops, with the MCP cold leg designated as item 25 and the hot leg as 26.

[0108] To increase the cavitation margin by working chamber coolant temperature reduction, as shown in FIG. 7, the reactor plant 2 coolant pump 5 may be installed downstream the steam generator 4 along the primary circuit coolant flow in the circulation loop on the MCP 3 cold leg 25.

[0109] In the other option shown in FIG. 8, to improve the reactor plant operation reliability, two reactor coolant pumps 5 may be installed in each circulation loop. That is, a reactor coolant pump 5 may be installed on both the hot leg 26 and cold leg 25 of the main circulation pipeline in a circulation loop. Reliability is increased by means of possibility of pump redundancy.

[0110] In another arrangement of the reactor plant, two reactor coolant pumps 5 of lower capacity may be installed in parallel on the cold leg 25 of the main circulation pipeline as shown in FIG. 9. This will allow to reduce the pump dimensions, increasing the reliability margin and improving reactor plant technical and economic performance.

[0111] In addition, provision may be made for gate valves 27 on the main circulation pipeline legs 25 and 26 of the reactor plant as shown in FIG. 10. This would allow to enhance the operation reliability of the reactor plant making it possible to isolate the steam generator from the reactor and perform repairs without shutting down the reactor plant.

[0112] The reactor plant functions as follows.

[0113] The process flow diagram of the reactor plant is double-circuit. The primary circuit is radioactive and located in a containment 1, comprising a VVER water-cooled water-moderated power reactor 2 and four circulation loops of the MCP 3, through which the primary circuit coolant, pressurized water (160 kgf/cm.sup.2), is pumped to a reactor core 2 by means of reactor coolant pumps 5. Water temperature at the reactor inlet is approximately 289° C., and 322° C. at the outlet. The water heated in the reactor 2 is supplied to steam generators 4 through four MCP pipelines 3. A steam pressurizer 6 maintains the pressure and level of the primary circuit coolant.

[0114] The secondary circuit is non-radioactive, consists of an evaporator and a feed water plant, a unit demineralization plant and a turbine generator (not shown). The primary circuit coolant is cooled down in the steam generators 4 transferring heat to the secondary circuit water. The saturated steam produced in the steam generators 4 is supplied to the turbine generator rotating the power generator by steam removal connection pipes 9 and the steam header.

Example

[0115] An NPP with a VVER reactor is constructed. To provide reliable reactor cooldown, the steam generator shall have the following parameters:

[0116] steam generator heat-exchange surface area H.sub.hes=6000 m.sup.2.

[0117] A steam generator with the following parameters has been manufactured for the reactor plant:

[0118] steam capacity per reactor plant steam generator D=1500 t/h, outer diameter of the primary circuit header in the drilled part D.sub.head=1200 mm, width of the heat-exchange tube central tunnel B.sub.1=200 mm, width of the heat-exchange tube tunnel opposite to the coolant header B.sub.2=200 mm, outer heat-exchange tube diameter d=16 mm, spacing between heat-exchange tubes in the horizontal heat-exchange bundle row S.sub.h=24 mm, spacing between heat-exchange tubes in the vertical heat-exchange bundle row S.sub.v=22 mm, number of heat-exchange tubes in the steam generator N.sub.tb=10,000 pcs, heat-exchange bundle arrangement identifier k=1 for the in-line arrangement, steam generator vessel tube filling height H=2300 mm,

[0119] According to the claimed invention, steam generator pressure vessel inner diameter D.sub.vess is selected from the range based on the following ratio:

[00007]$0.148.Math.D+0.637.Math.\sqrt{0.054.Math.D^2+3.142.Math.\frac{N_{\mathrm{tb}}.Math.S_h.Math.S_v}{k}}\le D_{\mathrm{vess}}\le 1.827.Math.H,.Math..Math.2825.Math..Math.\mathrm{mm}\le D_{\mathrm{vess}}\le 4202.Math..Math.\mathrm{mm}.$

[0120] Distance S between the centerlines of the coolant headers in the transverse direction is selected from a range based on the following ratio:

[00008]$0.4\le \frac{S}{D_{\mathrm{vess}}}\le 0.6,$

then 1130 mm≦S≦2521 mm.

[0121] Steam generator length Lv (along the inner surfaces of the elliptical bottoms) is selected from a range based on the following ratio:

[00009]$L_{\kappa }=D_{\mathrm{head}}+2.Math.\left[\left(\mathrm{ctg}\left(\frac{\alpha }{2}\right)-\frac{1}{\sin \left(\frac{\alpha }{2}\right)}\right).Math.\left(\frac{B_1}{2}+B_2+\left(\frac{\pi .Math.D_{\mathrm{head}}}{4.Math.S_{\mathrm{head}}}-1\right).Math.S_h\right)+\left(\frac{\pi .Math.D_{\mathrm{head}}}{4.Math.S_{\mathrm{head}}}-1\right).Math.S_h.Math.\frac{1}{\sin \left(\frac{\alpha }{2}\right)}+\Delta \right]+\frac{H_{\mathrm{hes}}.Math.{10}^6}{\pi .Math.d.Math.N_{\mathrm{tb}}},$

at 90°≦α≦150° and 300 mm≦Δ≦1000 mm, then 13,790 mm≦L.sub.v≦16,807 mm.

[0122] If steam generator pressure vessel inner diameter D.sub.vess is less than 2825 mm, then it will not be possible to securely mount heat-exchange tubes in such seam generator by means of spacing elements, therefore, there will be no space left for the same, and thus the steam generator design reliability requirement will not be met. A steam generator pressure vessel with an inner diameter exceeding 4202 mm is uneconomical to install in a reactor plant as it increases its specific amount of metal per structure, while the water content of the steam generated and plant efficiency are not improved, but the containment size is increased. The steam generator contains the same heat-exchange surface, therefore, the coolant remains within the same temperature range in the reactor plant MCP. As a result, the critical heat flux ratio does not increase in the core.

[0123] Steam generator length Lv (along the inner surfaces of the elliptical bottoms) of less than 13,790 mm does not provide the best performance of bending and fastening of U-shaped tubes in a bundle as the tube bending angle exceeds 150°, and the distance between the outer tubes of the bundle and the vessel bottom is less than 300 mm, which prevents installation of a bundle support.

[0124] Steam generator length Lv (along the inner surfaces of the elliptical bottoms) of more than 16,807 mm is not reasonable, as an increase in the steam generator pressure vessel length does not improve steam quality indicators, such as dehydration, and the heat-exchange surface area remains constant at 6000 m.sup.2 due to the fact that the steam generator length is not increased due to a greater number of heat-exchange tubes or heat-exchange surface area, but by closer bending angles and excessive gaps between the heat-exchange tube bundle and the steam generator bottoms. This results in an increased specific amount of metal per structure of the reactor plant steam generator without an increase in the critical heat flux ratio in the core or improvement of steam water content and pressure parameters in the steam generator, while the containment size is increased without any positive technical effect for reactor plant operation.

[0125] If distance S between the centerlines of the coolant headers in the transverse direction of at least 1130 mm is selected, the central part of the heat-exchange bundle of the steam generator will not be filled with tubes. As to fasten a heat-exchange tube in a hole in the primary circuit coolant side wall, its end shall have a straight section with a length exceeding the depth of such hole. If the condition is not fulfilled, then such heat-exchange tube cannot be placed and fastened in the coolant header side wall hole. Therefore, if the central part of the steam generator heat-exchange bundle is not filled with tubes, it will not allow to provide the specified number of heat-exchange tubes in the steam generator or the specified dimensions of the heat-exchange surface, which will compromise the performance indicators of the reactor plant.

[0126] If distance S between the centerlines of the coolant headers in the transverse direction of more than 2521 mm is selected, then it will not be possible to install the heat-exchange tube bundle near the steam generator pressure vessel side wall, which will not allow to provide the specified heat-exchange surface area and performance indicators of the reactor plant.