RU2785262C1 - Ship reactor plant contamination - Google Patents

Abstract

FIELD: ship technology.

SUBSTANCE: invention relates to the field of ship technology and relates to power hull structures, in particular the containment of the ship's reactor plant. The containment shell of the ship's reactor plant is a sealed steel case located above the metal-water protection tank, and consists of ribless panels, curved outward and having a cylindrical surface with a horizontal generatrix. On the rounding sections of deck cutouts between panels with a cylindrical surface, panels of double curvature are installed, each of which is a sector constituting 1/4 of the side surface of a circular barrel with a height equal to the distance between adjacent decks, with a diameter of the circumference of the barrel bases.

EFFECT: increase in the reliability and tightness of the containment shell of the reactor facility is achieved by significantly reducing the stress concentration.

2 cl, 9 dwg

Description

The invention relates to the field of ship engineering and relates to power hull structures, in particular, the containment shell of the ship's reactor plant and can be mainly used in the design of the containment shell of the reactor plant of an icebreaker or a floating power unit, the reactor compartment of which includes one or two reactor plants separated by flat longitudinal bulkheads of the cofferdam in the center plane of the vessel. In addition, the invention can find use for the containment of the reactor plant of a surface ship or transport ship with a nuclear power plant.

A well-known design of the protective fence of a ship reactor plant based on traditional structural power schemes widely used in shipbuilding (Barabanov N.V. Design of the hull of sea vessels. L .: Shipbuilding, 1981; Blinov V.M. Nuclear icebreakers. Murmansk: RosAtomFlot, 2014 ).

In such structures of the protective enclosure of the reactor plant, the main load-bearing elements that perceive all loading factors are flat bulkheads, the skin of which is reinforced by welded vertical tee profile posts. Racks are multi-span beams supported by decks and platforms. To date, the protective barriers of reactor installations of all built domestic nuclear icebreakers and floating power units are designed similarly to the above-mentioned protective barrier design.

The design loads for the protective fence of the reactor plant are determined by the "Rules for the Classification and Construction of Nuclear Ships and Floating Structures" of the Russian Maritime Register of Shipping. The load that causes the greatest stresses in the elements of the protective barrier is the internal pressure in the event of a reactor plant accident.

The disadvantages of the traditional design of the protective fence of the reactor plant are the irrational use of the strength characteristics of steel due to the uneven distribution of alternating bending stresses both along the length of the racks and along the height of their cross section, as well as a large amount of welding, hence the high labor intensity and high metal consumption of the protective fence.

Known design of the containment of the reactor plant of the vessel (Sochinskiy S. V. "Protective enclosure of the reactor compartment of the vessel", patent for invention No. 2726510), the closest in design features to the proposed invention and taken as a prototype, consisting of ribless cylindrical panels with a horizontal generatrix. The radius of curvature of the panels is determined from the condition of closest approximation to the momentless stress state of a closed circular cylindrical shell. The ribless design can significantly reduce the metal consumption of the containment and reduce the amount of welding.

The disadvantage of the prototype is the preservation of the traditional rectangular shape of the deck cutouts, the corners of which are a zone of significant concentration of stresses from internal pressure both for the containment itself and for the deck structures adjacent to it, and by installing thickened knees inside the protective fence in the plane of the decks, the problem of stress concentration cannot be solved. succeeded (the stresses in the knees are 70% higher than in decking without knees in the corners of the cutout). Meanwhile, the danger of crack development at the intersections of the protective fence with the decks is not only in the loss of strength, but also in the violation of the sealing of the shell, inside which in an emergency there is radioactive vapor at a temperature of up to 150 ° C and a pressure of up to 10 atmospheres.

The task to be solved by the claimed invention is to reduce dangerous stress concentration by rounding deck cutouts and replacing panels with a cylindrical surface in the rounding area with ribless panels of double curvature, each of which is a sector constituting ¼ of the side surface of a circular barrel. The thickness of both types of panels is the same.

The technical result is to increase the reliability and tightness of the reactor plant containment by significantly reducing the stress concentration.

The technical result is achieved by the fact that in the containment shell of the ship's reactor plant, which is a sealed steel case located above the metal-water protection tank, and consisting of ribless panels, curved outward and having a cylindrical surface with a horizontal generatrix, there are the following differences: in the areas of rounding deck cutouts between the panels with a cylindrical surface there are panels of double curvature, each of which is a sector that makes up ¼ of the side surface of a circular barrel with a height equal to the distance between adjacent decks, with a diameter of the circumference of the bases of the barrel, which is determined by the formula:

d=2R;

and with the diameter of the middle circumference of the barrel, which is determined by the formula:

D=2(R+h);

where:

d - diameter of the circumference of the bases of the barrel,

R - rounding radius of the deck cutout,

D - diameter of the median circumference of the barrel,

h - arrow of a panel segment with a cylindrical surface, determined by the formula:

h=r-c;

as well as the radius of curvature of panels with a cylindrical surface is determined by the formula:

where:

r - radius of curvature of panels with a cylindrical surface,

a - distance between adjacent decks,

c is the ratio of the area of the deck cut to its perimeter.

The essence of the invention is illustrated by drawings, where:

in fig. 1 shows the design of the containment from cylindrical panels and panels of double curvature, where:

1 - panels with a cylindrical surface;

2 - panels of double curvature;

in fig. 2 shows the geometry of panels having a cylindrical surface (according to the prototype), where:

r - radius of curvature of the panel with a cylindrical surface;

h - arrow of the panel segment with a cylindrical surface;

a - distance between decks (segment chord),

in fig. 3 shows the geometry of panels with a surface of double curvature (circular barrel), where:

r - radius of curvature of the panel with a cylindrical surface;

h - arrow of the panel segment with a cylindrical surface;

R - rounding radius of the deck cutout;

b - half the distance between decks (b=a/2);

in fig. 4a shows a traditional assembly of a protective fence, where

3 - flat longitudinal bulkhead of the cofferdam;

4 - cover of the upper hatch of the protective fence;

5 - longitudinal and transverse bulkheads of the protective fence;

6 - decks;

in fig. 4b shows the design of the protective shell according to the prototype in the assembly, where:

1 - panels with a cylindrical surface;

3 - flat longitudinal bulkhead of the cofferdam;

4 - cover of the upper hatch of the protective fence

6 - decks;

in fig. 4c shows the design of the protective shell from cylindrical panels and panels of double curvature in the assembly, where:

1 - panels with a cylindrical surface;

2 - panels of double curvature;

3 - flat longitudinal bulkhead of the cofferdam;

4 - cover of the upper hatch of the protective fence;

6 - decks;

fig. 5a shows the result of the calculation of the stress state of the traditional design of the protective fence;

fig. 5b shows the result of calculating the stress state of the protective fence structure according to the prototype;

fig. 5c shows the result of calculating the stress state of the containment structure from cylindrical panels and panels of double curvature.

The proposed containment of the reactor plant (Fig. 1) consists of panels that are curved outward and have a cylindrical surface with a horizontal generatrix (1), and on the sections of the deck cutouts rounding between the panels with a cylindrical surface, panels of double curvature (2) are installed, which are a sector, component 1A of the side surface of a circular barrel.

The initial information for determining the geometric parameters of panels of both types (radius of curvature r, segment boom h (Fig. 3), diameter of the median circumference of the barrel D, diameter of the circumference of the bases of the barrel d (not shown in Fig.) are:

- a - the distance between adjacent decks (Fig. 2),

- L - the length of the deck cutout (not shown in the figure),

- B - deck cutout width (not shown in Fig.),

- R - rounding radius of the deck cutout (Fig. 3).

The procedure for determining the geometric parameters of the panels is as follows. After calculating the area of the deck cutout A and its perimeter P (not shown in the figure), the ratio of the area of the deck cutout to its perimeter is determined:

c=A/P;

where:

A - deck cutout area;

Р - deck cutout perimeter;

further, the radius of curvature r and the arrow of the segment h of panels with a cylindrical surface (1) (Fig. 2) are determined

where

a - distance between adjacent decks;

c - the ratio of the area of the deck cut to its perimeter;

h=r-c;

then the diameters of the middle circumference of the barrel D and its bases d are determined

D=2(R+h);

d=2R;

where:

R - rounding radius of the deck cutout;

h - arrow of the panel segment with a cylindrical surface.

Knowing the height of the barrel and calculating the diameter of its median circle (D) and the diameter of the circumference of the bases of the barrel (d), it is possible to determine how the panel of double curvature is curved, which is a sector that makes up ¼ of the side surface of the circular barrel.

The technical essence of the proposed invention is illustrated by the results of a numerical experiment using the finite element method - calculations of the three described types of protective structures (Fig. 4a, 4b, 4c) for an internal pressure of 0.4 MPa with the following initial data:

- deck cutout length L=6400 mm;

- deck cutout width B=6000 mm;

- distance between adjacent decks a=3000 mm;

- reduced deck thickness - 20 mm;

- thickness of reinforced flooring sheets in the corners of the deck cutout - 30 mm.

установлены через 800 мм, на поперечных переборках -

через 600 мм.The thickness of the cladding sheets of the bulkheads of the traditional enclosure of the reactor facility (Fig. 4a) is 40 mm, vertical posts (welded T-bars) on the longitudinal bulkhead

installed after 800 mm, on transverse bulkheads -

through 600 mm.

The thickness of panels with a cylindrical surface according to the prototype of Fig. 4b and panels of double curvature in the variants of FIG. 4c, as well as the skins in the variant of FIG. 4a is taken equal to 40 mm with the same deck design.

In the variant of FIG. 4c two corners of the deck cutout have a rounding radius R=600 mm and with the dimensions of the deck cutout 6.4×6.0 m its area will be equal to A=37.971 m ² and the perimeter - P=26.285 m. With a distance between adjacent decks a= 3000 mm given values allow you to determine all the geometric parameters of panels with a cylindrical surface and panels of double curvature, their values will be equal to:

c=A/P=1445 mm;

h=r-c=638 mm;

D=2(R+h)=2476 mm;

d=2R=1200 mm.

According to the results of calculations of the stress state of the traditional design of the protective fence, the design of the protective shell according to the prototype and the proposed design of the protective shell from panels with a cylindrical surface and panels of double curvature in Fig. 5a, 5b, 5c shows the distributions of equivalent stresses, the maximum values of which are:

- in the traditional design of the protective fence - 475 MPa, (Fig. 5a);

- in the design of the protective shell according to the prototype - 376 MPa, (Fig. 5b);

- in the design of the containment from cylindrical panels and panels of double curvature - 264 MPa, (Fig. 5c).

In the proposed design option, the maximum equivalent stresses, as calculations show, will be 45% less than in a traditional fence, and 30% less than in the prototype design.

Thus, due to the installation of panels of double curvature between the panels having a cylindrical surface on the rounding sections of the deck cutouts, the stress concentration in the containment shell and decks in the area of the deck cutouts is significantly reduced, which achieves the claimed technical result - an increase in the reliability and tightness of the reactor plant containment shell. ship in an emergency.

Claims (17)

1. The containment of the ship's reactor plant, which is a sealed steel case located above the metal-water protection tank, and consisting of ribless panels, curved outwards and having a cylindrical surface with a horizontal generatrix, characterized in that in the areas of rounding of the deck cutouts between the panels with a cylindrical surface panels of double curvature are installed, each of which is a sector constituting 1/4 of the side surface of a circular barrel with a height equal to the distance between adjacent decks, with a diameter of the circumference of the barrel bases, which is determined by the formula: d=2R; and with the diameter of the middle circumference of the barrel, which is determined by the formula: D=2(R+h); where: d - diameter of the circumference of the bases of the barrel, R - rounding radius of the deck cutout, D - diameter of the median circumference of the barrel, h - arrow of the panel segment with a cylindrical surface. 2. The containment shell of the ship's reactor plant according to claim 1, characterized in that the boom of the panel segment with a cylindrical surface is determined by the formula: h=r-c; as well as the radius of curvature of panels with a cylindrical surface is determined by the formula:

where: r - radius of curvature of panels with a cylindrical surface, a - distance between adjacent decks, c is the ratio of the area of the deck cut to its perimeter.

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