阅读说明：本技术 模拟燃料表面沉积物对堆芯热工影响的实验装置及方法 (Experimental device and method for simulating thermal influence of fuel surface sediments on reactor core ) 是由 王明军 王幸君 王莹杰 侯延栋 巫英伟 田文喜 秋穗正 苏光辉 于 2020-07-07 设计创作，主要内容包括：本发明公开了一种模拟燃料表面沉积物对堆芯热工影响的实验装置及方法,该实验装置包括实验段、水箱、稳压器、冷凝器、高温高压泵、质量流量计、预热器、过滤器、NI数据采集系统、辅助系统、和配电系统；实验段由存在沉积物的锆合金包壳管、外套管、电极、引压管和T热电偶组成；水箱是回路的供水系统,通过注水管与实验主回路相连,连接的位置位于过滤器与冷凝器之间；冷凝器的上游是过滤器,按照冷却剂流通方向,冷凝器依次与高温高压泵、质量流量计、预热器、实验段、稳压器和过滤器相连；稳压器与实验主回路相连；辅助系统接入实验主回路；本发明能有效地模拟燃料元件包壳表面沉积物对于堆芯热工水力特性的影响,为相关研究提供可靠的实验模拟装置。(The invention discloses an experimental device and a method for simulating thermal influence of fuel surface sediments on a reactor core, wherein the experimental device comprises an experimental section, a water tank, a voltage stabilizer, a condenser, a high-temperature high-pressure pump, a mass flow meter, a preheater, a filter, an NI data acquisition system, an auxiliary system and a power distribution system; the experimental section consists of a zirconium alloy cladding tube with sediments, an outer sleeve, an electrode, a pressure guiding tube and a T thermocouple; the water tank is a water supply system of the loop, is connected with the experiment main loop through a water injection pipe, and is positioned between the filter and the condenser; the filter is arranged at the upstream of the condenser, and the condenser is sequentially connected with the high-temperature high-pressure pump, the mass flow meter, the preheater, the experimental section, the voltage stabilizer and the filter according to the flow direction of the coolant; the voltage stabilizer is connected with the experiment main loop; the auxiliary system is accessed to the experiment main loop; the invention can effectively simulate the influence of the surface deposits of the cladding of the fuel element on the thermohydraulic characteristics of the reactor core, and provides a reliable experimental simulation device for related research.)

1. The utility model provides an experimental apparatus of simulation fuel surface deposit to thermal engineering influence of reactor core which characterized in that: the system comprises an experimental section (10), a water tank (1), a voltage stabilizer (12), a condenser (3), a high-temperature high-pressure pump (4), a mass flow meter (6), a preheater (7), a filter (14), an NI data acquisition system (8), an auxiliary system (11) and a power distribution system; electrodes are welded at two ends of the experimental section (10), are connected with a direct current power supply (9), and simulate the surface heating of an actual fuel element through electric heating; the NI data acquisition system (8) is connected with the experimental section (10) through an experimental section measurement system (17) and is used for measuring the temperature and pressure parameters of the experimental section (10); the high-temperature high-pressure pump (4) is sequentially connected with the mass flow meter (6) and the preheater (7) to form an upstream environment of the experiment section (10), and then is connected with the experiment section (10) through the preheater (7), the outlet of the experiment section (10) is connected with the filter (14), the filter (14) is connected with the condenser (3) and finally is connected to the high-temperature high-pressure pump (4) to form a closed experiment main loop; the voltage stabilizer (12) is connected into an experiment main loop through a pipe section connected between the experiment section (10) and the filter (14), a branch pipe section led out from an inlet pipeline of the voltage stabilizer (12) is connected with the auxiliary system (11), and the pressure of the experiment main loop is regulated and controlled through the auxiliary system (11) and the voltage stabilizer (12); the top end of the pressure stabilizer (12) is connected with an argon bottle (13) for vacuumizing and maintaining the experiment main loop; the water tank (1) is connected to a pipe section between the filter (14) and the condenser (3) through a pipeline so as to fill water into the experimental main loop, and an electric heater (2) is arranged in the water tank (1) and used for heating deionized water in the water tank so as to remove non-condensable gas; meanwhile, a thermometer (15) and a pressure gauge (16) are uniformly arranged between the high-temperature high-pressure pump (4) and the mass flow meter (6) and on the pipe sections at the inlet and the outlet of the experiment section (10) and used for monitoring the temperature and the pressure of the experiment main loop.

2. The experimental device for simulating the thermal effect of the fuel surface deposits on the reactor core as claimed in claim 1, wherein: the experimental section (10) consists of a zirconium alloy cladding tube (10-1) with sediments, a T thermocouple (10-2), an outer sleeve (10-3), an electrode (10-4) and a pressure guiding tube (10-5) and is used for simulating a flow heat exchange process in a pressurized water reactor core; in the test section (10), a zirconium alloy cladding tube (10-1) with deposits is prepared by placing a zirconium alloy sample in an autoclave simulating a pressurized water reactor environment in a corrosion deposition mode, an annular flow channel (10-8) of a coolant is formed between an outer sleeve (10-3), and the annular flow channel (10-8) is connected with an experiment main loop pipeline through a flow channel inlet (10-7) and a flow channel outlet (10-6) which are formed by opening a hole in one side surface of the outer sleeve (10-3); electrodes are welded at two ends of the zirconium alloy cladding tube (10-1) with the deposit and are connected with a direct current power supply (9) to provide heating power; a plurality of T thermocouples (10-2) are arranged on the inner wall surface of the zirconium alloy cladding tube (10-1) with the sediment for measuring the temperature of the wall surface; the pressure and the pressure difference of an inlet and an outlet of the experimental section (10) are measured through two pressure leading pipes (10-5); an inlet section (10-9) with the length more than 60 times of the hydraulic diameter is reserved at the upstream of the heating section of the annular flow passage (10-8), and fully developed turbulence can be guaranteed to be established.

3. The experimental device for simulating the thermal effect of the fuel surface deposits on the reactor core as claimed in claim 1, wherein: the water tank (1) is connected to a pipe section between the filter (14) and the condenser (3) through a water injection pipe section, deionized water is contained in the water tank, and the deionized water is heated to boiling through an electric heater (2) in the water tank (1) before an experiment, so that condensed gas in the deionized water is removed; before the experiment begins, the water tank (1) injects water into the experiment main loop through the water injection pipe section, and the water injection is stopped in the experiment process.

4. The experimental device for simulating the thermal effect of the fuel surface deposits on the reactor core as claimed in claim 1, wherein: the auxiliary system (11) and the voltage stabilizer (12) are used for adjusting the pressure in the experiment main loop, so that the pressure does not exceed 15.5MPa at most.

5. The experimental device for simulating the thermal effect of the fuel surface deposits on the reactor core as claimed in claim 1, wherein: deionized water in the experiment main loop is heated to the inlet temperature required by the experiment through the preheater (7), dirt and impurities in the water are removed through the filter (14), the heat of the water heated through the experiment section (10) is taken away through the condenser (3), and the experiment cycle is completed.

6. The experimental method of the experimental device for simulating the thermal influence of the fuel surface deposit on the reactor core as claimed in any one of claims 1 to 5, is characterized in that: before the experiment begins, the deionized water is heated to a boiling state by using the electric heater (2) in the water tank (1), non-condensable gas in the deionized water is removed, and the interference of the non-condensable gas on the experiment result is eliminated; then injecting deionized water into the experimental main loop through a water injection pipe section, and adjusting the pressure in the loop to the required pressure by using an auxiliary system (11); starting a high-temperature high-pressure pump (4), and driving deionized water to flow through a flowmeter (6), a preheater (7), an experimental section (10), a voltage stabilizer (12), a filter (14) and a condenser (3) in sequence; then starting a power supply of the preheater (7) and adjusting the power of the preheater to heat the deionized water in the experimental main loop to the inlet temperature required by the experiment, and starting the condenser (3) to take away the heat of the deionized water; finally, adjusting the degree of supercooling of an inlet of the experimental section, the pressure of an experimental main loop and the heating power and flow of the experimental section (10), simulating the reactor core through the experimental section (10), completing single-phase and boiling two-phase flow heat transfer experiments under different working conditions under the condition that the sediment on the surface of the shell exists, and simultaneously acquiring data of flow, temperature, pressure and differential pressure by using an NI data acquisition system (8); changing the experimental section (10) prepared under different conditions, and repeating the processes to obtain experimental data under different sediment conditions; by analyzing the characteristics of flow pressure drop and heat exchange coefficient, the influence rule of operation parameters, namely the pressure, mass flow rate and heat flow density of an experimental main loop and the roughness of surface sediments on the heat transfer characteristics of single-phase and boiling two-phase flow is researched.

Technical Field

The invention relates to the field of thermal and hydraulic characteristic experiments of reactor cores of light water reactors, in particular to an experimental device and method for simulating the influence of deposits on the surfaces of fuel elements of the light water reactors on the thermal and hydraulic characteristics of the reactor cores.

Background

Nuclear energy is an important pillar of the national energy strategy and also an important guarantee for the sustainable development of energy, and nuclear safety is a fundamental guarantee and a fundamental stone for developing nuclear energy and is a fundamental problem related to the energy safety and the economic and social development of China. The fuel element is used as a core component of the nuclear reactor, energy is continuously released in the fuel element through a chain type nuclear fission reaction source, the fuel element cladding is used as a first barrier for preventing radioactive substances from leaking, high reliability and integrity of the fuel element cladding in the operation period of the reactor are important prerequisites of reactor safety, and the fuel element cladding has important significance for realizing a nuclear safety target of actually eliminating the possibility of releasing a large amount of radioactivity and improving the safety of a nuclear power system. The surface of the cladding of the fuel element of the light water reactor core can form oxide layers and sediments when the fuel element operates under the environment of long-term high temperature, high pressure and strong radiation. The existence of the sediments can seriously affect the reactor core neutron physics and the heat transfer characteristics of fuel elements and a coolant, cause the hazards of reactor core power deviation, local heat transfer deterioration, local corrosion aggravation damage and the like, and bring great potential safety hazards to the safe operation of the nuclear reactor.

At present, relevant research is carried out at home and abroad, but no feasible experimental method is available for researching the influence of the deposits on the surface of the fuel element on the thermal and hydraulic characteristics of the reactor core. At present, domestic researches on the surface deposits of the fuel elements are relatively few, and related researches are mostly carried out by countries such as Europe, America, Japan and Korean.

For example, Korean patent application Nos. KR2020011277-A and KR2105037-B1 disclose an apparatus for analyzing the effect of surface deposits on the output power of fuel elements of nuclear reactors and measuring the amount of deposit formation and boron concentration. The device mainly focuses on measuring the influence of the surface deposits of the fuel elements on the operating efficiency of the reactor, and does not pay attention to the thermohydraulic problem.

For example, European patent application Nos. EP 247235-A4, EP 247235-B1, EP 247235-A1, U.S. patent application Nos. US2011019790-A1, US9530527-B2, and Japanese patent application No. JP2013500472-W JP5645206-B2, and the like, jointly disclose an analytical method for analyzing two different types of CRUDs (fuel element surface deposits). The method mainly focuses on analyzing the components and the formation mechanism of the deposits on the surface of the fuel element and does not relate to the influence of the deposits on the thermohydraulic characteristics of the reactor core.

Description of the invention

In order to overcome the defects of the prior art, the invention provides an experimental device and method for simulating the influence of the surface deposits of the cladding of the fuel element on the thermohydraulic characteristics of the reactor core, which can be used for researching the influence mechanism of the surface deposits of the fuel element on the thermohydraulic characteristics of the reactor core, and provides an important theoretical basis for analyzing the influence of the surface deposits of the fuel element on the safe operation of the reactor and reducing the damage to the reactor in the operation process.

In order to achieve the purpose, the invention adopts the following technical scheme:

an experimental device for simulating thermal influence of fuel surface sediments on a reactor core comprises an experimental section 10, a water tank 1, a voltage stabilizer 12, a condenser 3, a high-temperature high-pressure pump 4, a mass flowmeter 6, a preheater 7, a filter 14, an NI data acquisition system 8, an auxiliary system 11 and a power distribution system; electrodes are welded at two ends of the experimental section 10, are connected with the direct-current power supply 9, and simulate the heating of the surface of an actual fuel element through electric heating; the NI data acquisition system 8 is connected with the experimental section 10 through an experimental section measurement system 17, and measures the temperature and pressure parameters of the experimental section 10; the high-temperature high-pressure pump 4 is sequentially connected with a mass flow meter 6 and a preheater 7 to form an upstream environment of an experimental section 10, then is connected with the experimental section 10 through the preheater 7, an outlet of the experimental section 10 is connected with a filter 14, the filter 14 is connected with a condenser 3, and finally is connected to the high-temperature high-pressure pump 4 to form a closed experimental main loop; the voltage stabilizer 12 is connected to an experiment main loop through a pipe section connected between the experiment section 10 and the filter 14, a branch pipe section led out from an inlet pipeline of the voltage stabilizer 12 is connected with the auxiliary system 11, and the pressure of the experiment main loop is regulated and controlled through the auxiliary system 11 and the voltage stabilizer 12; the top end of the voltage stabilizer 12 is connected with an argon bottle 13 for vacuumizing and maintaining the main experimental loop; the water tank 1 is connected to a pipe section between the filter 14 and the condenser 3 through a pipeline to inject water into the experiment main loop, and the electric heater 2 is arranged in the water tank 1 and used for heating deionized water in the water tank to remove non-condensable gas; and meanwhile, a thermometer 15 and a pressure gauge 16 are uniformly arranged between the high-temperature high-pressure pump 4 and the mass flow meter 6 and on the pipe sections at the inlet and the outlet of the experiment section 10, and are used for monitoring the temperature and the pressure of the experiment main loop.

The experimental section 10 consists of a zirconium alloy cladding tube 10-1 with sediments, a T thermocouple 10-2, an outer sleeve 10-3, an electrode 10-4 and a pressure guiding tube 10-5 and is used for simulating a flow heat exchange process in a pressurized water reactor core; in the test section 10, a zirconium alloy cladding tube 10-1 with deposits is prepared by placing a zirconium alloy sample in an autoclave simulating a pressurized water reactor environment in a corrosion deposition mode, an annular flow channel 10-8 of a coolant is formed between an outer sleeve 10-3 and the zirconium alloy cladding tube 10-1, and the annular flow channel 10-8 is connected with a main experimental loop pipeline through a flow channel inlet 10-7 and a flow channel outlet 10-6 which are formed by opening holes in one side surface of the outer sleeve 10-3; electrodes are welded at two ends of the zirconium alloy cladding tube 10-1 with the sediment and are connected with a direct current power supply 9 to provide heating power; a plurality of T thermocouples 10-2 are arranged on the inner wall surface of the zirconium alloy cladding tube 10-1 with the sediment for measuring the temperature of the wall surface; measuring the pressure and the pressure difference of an inlet and an outlet of the experimental section 10 through two pressure leading pipes 10-5; an inlet section 10-9 with the length more than 60 times of the hydraulic diameter is reserved at the upstream of the heating section of the annular flow passage 10-8, so that fully developed turbulent flow can be established.

The water tank 1 is connected to a pipe section between the filter 14 and the condenser 3 through a water injection pipe section, deionized water is contained in the water tank, and before an experiment, the deionized water is heated to boiling through the electric heater 2 in the water tank 1 to remove condensed gas in the deionized water; before the experiment begins, the water tank 1 injects water into the experiment main loop through the water injection pipe section, and the water injection is stopped in the experiment process.

The pressure in the experimental main loop is regulated by the auxiliary system 11 and the voltage stabilizer 12, so that the pressure does not exceed 15.5MPa at most.

Deionized water in the experiment main loop is heated to about 350K of inlet temperature required by the experiment through the preheater 7, dirt and impurities in the water are removed through the filter 14, the heat of the water heated by the experiment section 10 is taken away through the condenser 3, and the experiment circulation is completed.

The experimental method of the experimental device for simulating the thermal influence of the fuel surface sediments on the reactor core comprises the following steps of heating deionized water to a boiling state by using the electric heater 2 in the water tank 1 before an experiment is started, removing non-condensable gas in the deionized water, and eliminating the interference of the non-condensable gas on an experimental result; then injecting deionized water into the experimental main loop through a water injection pipe section, and adjusting the pressure in the loop to the required pressure by using an auxiliary system 11; starting the high-temperature high-pressure pump 4, and driving deionized water to flow through a flowmeter 6, a preheater 7, an experimental section 10, a voltage stabilizer 12, a filter 14 and a condenser 3 in sequence; then starting a power supply of the preheater 7 and adjusting the power of the preheater to heat the deionized water in the experimental main loop to the inlet temperature required by the experiment, and starting the condenser 3 to take away the heat of the deionized water; finally, adjusting the degree of supercooling of an inlet of the experiment section, the pressure of an experiment main loop and the heating power and flow of the experiment section 10, simulating the reactor core through the experiment section 10, completing single-phase and boiling two-phase flow heat transfer experiments under different working conditions under the condition that the sediment on the surface of the shell exists, and simultaneously acquiring flow, temperature, pressure and differential pressure data by using an NI data acquisition system 8; changing the experimental section 10 prepared under different conditions, and repeating the above processes to obtain experimental data under different sediment conditions; by analyzing the characteristics of flow pressure drop and heat exchange coefficient, the influence rule of operation parameters, namely the pressure, mass flow rate and heat flow density of an experimental main loop and the roughness of surface sediments on the heat transfer characteristics of single-phase and boiling two-phase flow is researched.

Compared with the prior art, the invention has the following beneficial results:

1. the invention aims at the research on the influence of the surface deposits of the fuel elements on the thermo-hydraulic characteristics of a core. At present, the research on sediments at home and abroad mainly aims at the formation mechanism and the corrosion mechanism, and the research on the influence of thermal engineering and hydraulic power is little. The invention helps to make up for the blank in this field.

2. The experimental device is invented aiming at the influence of sediments on the surface of the light water reactor fuel element on the thermal hydraulic characteristics of the reactor core, and the zirconium alloy sample is placed in the autoclave corrosion deposition preparation experimental section for simulating the pressurized water reactor environment, so that the heat transfer and the peripheral flow of the light water reactor fuel element can be reasonably and effectively simulated, and the experimental device has the advantages of simple integral structure, easiness in processing, low cost and strong operability.

3. The invention can reasonably and effectively simulate the influence of the fuel surface sediments on the thermal hydraulic characteristics of the reactor core under different conditions by adjusting a plurality of experimental condition parameters such as the degree of supercooling at the inlet, the pressure of the experimental main loop, the heating power and the like, changing experimental sections and the like.

Drawings

FIG. 1 is a schematic view of the overall structure of the experimental apparatus of the present invention.

FIG. 2 is a schematic structural diagram of an experimental section of the device of the present invention.

Detailed Description

The invention is described in detail below with reference to the following figures and examples:

as shown in FIG. 1, the experimental device for simulating the thermal influence of fuel surface sediments on a reactor core comprises an experimental section 10, a water tank 1, a voltage stabilizer 12, a condenser 3, a high-temperature high-pressure pump 4, a mass flow meter 6, a preheater 7, a filter 14, an NI data acquisition system 8, an auxiliary system 11 and a power distribution system; electrodes are welded at two ends of the experimental section 10, are connected with the direct-current power supply 9, and simulate the surface heating of an actual fuel element through electric heating; the NI data acquisition system 8 is connected with the experimental section 10 through an experimental section measurement system 17, and measures the temperature and pressure parameters of the experimental section 10; the high-temperature high-pressure pump 4 is sequentially connected with a mass flow meter 6 and a preheater 7 to form an upstream environment of an experimental section 10, then is connected with the experimental section 10 through the preheater 7, an outlet of the experimental section 10 is connected with a filter 14, the filter 14 is connected with a condenser 3, and finally is connected to the high-temperature high-pressure pump 4 to form a closed experimental main loop; the voltage stabilizer 12 is connected to an experiment main loop through a pipe section connected between the experiment section 10 and the filter 14, a branch pipe section led out from an inlet pipeline of the voltage stabilizer 12 is connected with the auxiliary system 11, and the pressure of the experiment main loop is regulated and controlled through the auxiliary system 11 and the voltage stabilizer 12; the top end of the voltage stabilizer 12 is connected with an argon bottle 13 for vacuumizing and maintaining the main experimental loop; the water tank 1 is connected to a pipe section between the filter 14 and the condenser 3 through a pipeline to inject water into the experiment main loop, and the electric heater 2 is arranged in the water tank 1 and used for heating deionized water in the water tank to remove non-condensable gas; and meanwhile, a thermometer 15 and a pressure gauge 16 are uniformly arranged between the high-temperature high-pressure pump 4 and the mass flow meter 6 and on the pipe sections at the inlet and the outlet of the experiment section 10, and are used for monitoring the temperature and the pressure of the experiment main loop.

As shown in FIG. 2, the experimental section 10 consists of a zirconium alloy cladding tube 10-1 with sediment, a T thermocouple 10-2, an outer sleeve 10-3, an electrode 10-4 and a pressure guiding tube 10-5 and is used for simulating a flow heat exchange process in a pressurized water reactor core; in the test section 10, a zirconium alloy cladding tube 10-1 with deposits is prepared by placing a zirconium alloy sample in an autoclave simulating a pressurized water reactor environment in a corrosion deposition mode, an annular flow channel 10-8 of a coolant is formed between an outer sleeve 10-3 and the zirconium alloy cladding tube 10-1, and the annular flow channel 10-8 is connected with a main experimental loop pipeline through a flow channel inlet 10-7 and a flow channel outlet 10-6 which are formed by opening holes in one side surface of the outer sleeve 10-3; electrodes are welded at two ends of the zirconium alloy cladding tube 10-1 with the sediment and are connected with a direct current power supply 9 to provide heating power; a plurality of T thermocouples 10-2 are arranged on the inner wall surface of the zirconium alloy cladding tube 10-1 with the sediment for measuring the temperature of the wall surface; measuring the pressure and the pressure difference of an inlet and an outlet of the experimental section 10 through two pressure leading pipes 10-5; an inlet section 10-9 with the length more than 60 times of the hydraulic diameter is reserved at the upstream of the heating section of the annular flow passage 10-8, so that fully developed turbulent flow can be established.

According to the experimental method of the experimental device for simulating the thermal influence of the fuel surface sediments on the reactor core, before the experiment begins, the electric heater 2 in the water tank 1 is used for heating the deionized water to a boiling state, the non-condensable gas in the deionized water is removed, and the interference of the non-condensable gas on the experimental result is eliminated; then injecting deionized water into the experimental main loop through a water injection pipe section, and adjusting the pressure in the loop to the required pressure by using an auxiliary system 11; starting the high-temperature high-pressure pump 4, and driving deionized water to flow through a flowmeter 6, a preheater 7, an experimental section 10, a voltage stabilizer 12, a filter 14 and a condenser 3 in sequence; then starting a power supply of the preheater 7 and adjusting the power of the preheater to heat the deionized water in the experimental main loop to the inlet temperature required by the experiment, and starting the condenser 3 to take away the heat of the deionized water; finally, adjusting the degree of supercooling of an inlet of the experiment section, the pressure of an experiment main loop and the heating power and flow of the experiment section 10, simulating the reactor core through the experiment section 10, completing single-phase and boiling two-phase flow heat transfer experiments under different working conditions under the condition that the sediment on the surface of the shell exists, and simultaneously acquiring flow, temperature, pressure and differential pressure data by using an NI data acquisition system 8; changing the experimental section 10 prepared under different conditions, and repeating the above processes to obtain experimental data under different sediment conditions; by analyzing the characteristics of flow pressure drop and heat exchange coefficient, the influence rule of operation parameters, namely the pressure, mass flow rate and heat flow density of an experimental main loop and the roughness of surface sediments on the heat transfer characteristics of single-phase and boiling two-phase flow is researched.

The foregoing is illustrative of the present invention only and is not to be construed as limiting thereof, and it will be apparent to those skilled in the art that numerous and varied substitutions and modifications may be made without departing from the spirit of the invention and the scope of the invention is to be determined by the appended claims.