NUCLEAR POWER PLANT AND DEVICE FOR FEEDING A COVER GAS INTO THE PLANT

Abstract

This invention relates to nuclear power engineering and may be used in power plants with liquid metal lead containing coolants, particularly in fast neutron reactors.

The invention helps improve the safety of nuclear power plants. For this purpose, a nuclear power plant is proposed comprising: a reactor vessel with central and peripheral sections; a reactor cavity with a core located in the central part of the vessel; liquid metal coolant, at least one circulation pump for circulating the liquid metal coolant and at least one steam generator, located in the peripheral section of the vessel; a cavity with shielding gas located above the coolant; at least one shielding gas dispenser located in the peripheral section of the vessel, above the top cut of the steam generator in the suction area of the circulating pump comprising an intake and working sections, with the intake section located in the shielding gas cavity and having openings in its upper part, and the working section located under the free level of the liquid metal coolant.

Claims

1. A nuclear power plant comprising: a reactor vessel with central and peripheral sections; a reactor cavity with a core located in the central part of the vessel; liquid metal coolant, at least one circulation pump for circulating the liquid metal coolant and at least one steam generator, located in the peripheral section of the vessel; a cavity with shielding gas located above the coolant; at least one shielding gas dispenser located in the peripheral section of the vessel, above the top cut of the steam generator in the suction area of the circulating pump comprising an intake and working sections, with the intake section located in the shielding gas cavity and having openings in its upper part, and the working section located under the free level of the liquid metal coolant.

2. The plant according to claim 1, in which the shielding gas device is a dispenser, with its working section designed as a combination of a lower rotating disc secured to the hollow shaft and an upper stationary disc located in the intake section. The two discs are installed with a clearance, with the movable disk being hollow and having axial holes connected to the clearance between the discs and the lower disc cavity.

3. The plant according to claim 1, with the shielding gas device connected to the motor mounted outside the cavity of the plant housing with the use of a magnetic coupling.

4. A shielding gas device for the nuclear power plant, with the shielding gas device represented by a dispenser, with its working section designed as a combination of a lower rotating disc secured to the hollow shaft and an upper stationary disc located in the intake section. The two discs are installed with a clearance, with the movable disk being hollow and having axial holes connected to the clearance between the discs and the lower disc cavity.

Description

INVENTION DISCLOSURE

[0040] The invention is shown in FIGS. 1, 2 and 3.

[0041] FIG. 1 shows the longitudinal axial section of one of the embodiments of the nuclear power plant.

[0042] FIG. 2 is a plan view of a portion of the reactor facility at the location of the gas dispenser.

[0043] FIG. 3 shows the shielding gas device;

[0044] The following notations designations are used in the figures:

[0045] 1core;

[0046] 2peripheral part of the vessel;

[0047] 3shielding gas dispenser;

[0048] 4liquid metal coolant;

[0049] 5shielding plug;

[0050] 6reactor vessel;

[0051] 7steam generator;

[0052] 8shielding gas cavity;

[0053] 9circulation pump;

[0054] 10reactor cavity;

[0055] 11dispenser intake section;

[0056] 12dispenser working section;

[0057] 13lower rotating disc;

[0058] 14upper stationary disc;

[0059] 15hollow shaft;

[0060] 16openings in dispenser intake section;

[0061] 17dispenser mounting flange;

[0062] 18driven magnetic coupling half;

[0063] 19driving magnetic coupling half;

[0064] 20sealed motor;

[0065] 21axial openings in lower rotating disc;

[0066] 22cavity in lower rotating disk;

[0067] 23clearance between the discs

[0068] The nuclear power plant comprises a nuclear reactor with a liquid metal coolant (4), a reactor cavity (10) with a core (1) and a shielding plug (5), at least one steam generator (7), at least one circulation pump (9), a cavity (8) with the shielding gas, and at least one device for gas mixture injection into the liquid metal coolant loop (4).

[0069] The reactor cavity (10) with the core (1) is located in the central part of the reactor vessel (6) under the free level of the liquid metal coolant (4).

[0070] The steam generator (7) and the circulating pump (9) are located in the peripheral part (2) of the vessel (6) of the reactor plant.

[0071] The shielding gas cavity (8) is located above the level of the liquid metal coolant (4).

[0072] The device for gas mixture injection into the liquid metal coolant loop (4) is represented by a gas dispenser (3) located in the peripheral area of the vessel (6) above the top cut of the steam generator (7) in the suction area of the circulation pump (9).

[0073] The dispenser (3) has an intake section (11) with openings (16), a working section (12) with the lower rotating disc (13) secured to the hollow shaft (15) and the upper stationary disc (14) secured to or combined with the intake section (11).

[0074] The intake section (11) of the gas dispenser (3) with its openings (16) is located in the shielding gas cavity (8).

[0075] The dispenser (3) is secured to the liquid metal circuit using a flange (17).

[0076] The upper part of the gas dispenser (3) is connected to a sealed motor (20) mounted outside the cavity 6 in the reactor vessel with the use of a magnetic coupling, where no.18 is the driving magnetic coupling half and no.19 is the driven magnetic coupling half.

[0077] The lower rotating disk (13) has axial openings (21) located along its periphery and is hollow. (cavity (22))

[0078] The discs are installed with a clearance (23).

[0079] The working section (12) of the gas dispenser (3), designed in the form of a rotating disc (13) and a stationary disc (14), is located under the free level of the liquid metal coolant (4). This arrangement prevents shielding gas separation and directs the liquid metal coolant flow to the suction of the circulation pump (9).

[0080] The plant is operated as follows.

[0081] In the process of oxide removal from the liquid metal coolant and reactor circuit surfaces, the nuclear power plant is operated with the steam generators (7) drained, under isothermal conditions, at the minimum controlled power level (0.001%). The liquid metal coolant (4) is warmed by the circulating pumps (9) (due to pump blade friction against the liquid metal coolant (4)).

[0082] When the sealed motor (13) is activated, the lower disc (20) of the working section (12) of the dispenser (3) rotates at a predetermined angular velocity (n up to 3000 rpm). As a result of liquid metal coolant (13) motion relative to the lower disc (23), a low-pressure area is formed in the clearance, which induces injection of gas from the cavity (22) of the lower disc (13) through the openings (21) in the top of the lower disc (13) into the clearance (23).

Due to the velocity gradient of the liquid metal coolant, the bubbles in the clearance are fragmented and the finely-dispersed gaseous phase flows jointly with the coolant from the clearance (23) into the main flow of the lead-bismuth coolant (4).

[0083] Shielding gas injection into the flow of the liquid metal coolant (4) results in destruction of PbO-based slags and subsequent improvement of the physical and chemical properties of the liquid metal coolant (4).

[0084] The authors performed computational studies in relation to a nuclear power plant with a lead-bismuth coolant with two circulation pumps (9) and steam generators (7).

[0085] The total volumetric flow rate of the liquid metal coolant 4 at the suction of the circulation pump 9 amounts to 0.64 m.sup.3/s; the volumetric flow of the shielding gas (a mixture of H.sub.2-H.sub.2OAr) is 0.00008 m.sup.3/s; the temperature of the liquid metal coolant 4 is 400 to 450 C.

[0086] The duration of shielding gas supply to the liquid metal coolant flow (4) is 168 hours.

[0087] It is shown that injection of the shielding gas results in its efficient delivery to the PbO-based slag and their complete (100%) destruction with subsequent removal of the slag from the liquid metal coolant and normalization of its circulation.

[0088] This increases the safety of the nuclear power plant by ensuring normalization of liquid metal coolant circulation, more efficient removal of slags from the coolant and better removal of corrosion from metal surfaces.