RIA Simulation Test Device
The RIA (Reactivity I nitiated Accident) simulation test simulates the RIA accident conditions of nuclear reactors. RIA accident conditions are accidents caused by reactivity, which are generally caused by the rapid increase of reactivity, such as rod ejection and uncontrolled withdrawal of control rod assemblies. The specific manifestation is that the internal pressure of the fuel rod and the surface temperature of the cladding both increase rapidly, eventually causing the cladding tube to soften, expand, bubble and then burst.
The simulated RIA test device is a test device used to simulate the simultaneous rapid increase in the internal pressure and temperature of the fuel cladding tube. That is, the sample tube is initially at normal temperature and pressure conditions (or specified temperature and pressure conditions), and then the internal pressure and surface temperature of the sample tube are increased at a set rate at the same time until the sample tube is destroyed and the test ends.
If conditions permit (if the temperature can be increased by tens of degrees Celsius within seconds, it is meaningful to consider increasing the temperature and pressure at the same time), it is possible to consider increasing the internal pressure of the cladding tube and the surface temperature of the cladding tube rapidly and synchronously, so as to more realistically simulate the reactivity introduction accident conditions in the nuclear reactor. Generally speaking, it is difficult to achieve a rapid increase in the internal pressure and the surface temperature of the cladding in the environment outside the reactor. At this time, the test can be simplified to a constant temperature rapid pressurization test and a constant pressure rapid temperature increase test. The constant temperature rapid pressurization test is to keep the cladding tube at a certain temperature and quickly pressurize the inside of the cladding tube until the cladding tube ruptures; the constant pressure rapid temperature increase test is to quickly increase the cladding temperature under a certain pressure until the cladding tube ruptures.
Sample parameters:
The test specimen is a hollow tube. Materials can be filled into the test tube to reduce the internal volume, which is beneficial to the test. The fixing, sealing, loading and unloading of the tube should be safe and reliable, and easy to operate. The detailed parameters of the test specimen are as follows:
Description | Parameter | Remark |
Sample material | Zirconium alloy, Fe-Cr-Al, Molybdenum alloy, SiC composite ceramics, MAX phase ceramics |
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Sample size | A thin-walled tube with an outer diameter of φ9~13mm and a wall thickness of 0.2~1.5mm (nominal diameter φ10, nominal wall thickness 0.6mm, the length can be changed according to experimental requirements, but it must be within the meter level |
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(Table 1 )
Test content:
In the development of accident-tolerant fuel cladding, the following tests were completed using the simulated RIA test device:
(1) High temperature rapid pressurization test
Seal one end of the cladding tube sample and connect the other end to the pressure source device (it is also possible to connect both ends to the pressure source, but the fuel rod cladding tube should not be subject to axial constraints). The entire cladding tube is inside the heating furnace, and protective gas is introduced into the furnace. The maximum operating temperature of the fuel rod cladding is 500°C. Heat the cladding tube to the operating temperature in a protective atmosphere, and then quickly load the pressure with a maximum pressure increase rate of 5.5GPa/s until the cladding tube fails. Record the maximum internal pressure when the cladding tube sample fails.
(2) High-pressure rapid temperature rise test
Seal one end of the cladding tube sample and connect the other end to the pressure source device (it is also possible to consider connecting both ends to the pressure source, but the fuel rod cladding tube should not be subject to axial constraints), and pressurize it to a certain set pressure. When the cladding tube is filled with the set pressure, the initial internal pressure of the cladding tube can be kept unchanged, and then heated. The internal pressure of the cladding tube is not restricted during the heating process; the internal pressure can also be maintained constant during the heating process by technical means. Rapidly heat the surface of the cladding tube by electromagnetic induction or other heating methods, with a maximum heating rate of 200℃/ s until the cladding tube fails. Record the maximum surface temperature of the cladding tube sample when it fails .
Key technical points of this experiment
A pressure device that can increase the internal pressure of the cladding tube at high speed;
Resistant to high temperature working medium;
Heating device for rapidly increasing the surface temperature of cladding tube
Effective sealing of cladding tube specimens.
Technical index requirements:
The fuel rod cladding RIA simulation test device is a highly integrated test device with the functions of constant temperature rapid pressure increase and constant pressure rapid temperature increase. The detailed parameters are as follows:
(Constant temperature rapid pressure rise test)
name | parameter | Remark |
Constant temperature rapid heating test indicators | Sample | Cladding sample material | See Table 1 |
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Cladding sample length | 200mm ≤ L ≤ 320mm |
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Sample quantity per time | ≥ 1 |
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Cladding tube connection method | One end is connected to the pressure source. The other end is a slip seal or is also connected to the pressure source. And ensure that the cladding tube is not restricted by load in the axial direction. (Consider that the pressure source end is fixed and the other end is suspended) |
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High temperature furnace | Heating capacity | The maximum heating temperature of the cladding is 500℃. |
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Temperature control method | Three-point temperature control or better |
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Temperature zone size | Ensure that the high temperature furnace uniform temperature zone can cover the cladding sample |
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Cladding temperature measurement method | Thermocouple contact measurement | Non-contact measurement |
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Temperature measurement method | Three-point measurement | Midpoint measurement |
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Temperature measurement resolution | ≤ 0.5℃ | 1℃ |
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Temperature measurement accuracy | 1% of indicated value | 2% of indicated value |
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Temperature Measurement Instructions | Use contact measurement whenever possible. If contact measurement has technical difficulties, consider using non-contact measurement. |
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High temperature furnace heating and cooling rate | 5-10 ℃ /s | Average value over a period of time |
Stressors | Pressure medium | High temperature silicone oil |
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Work Pressure | Maximum pressure 300 Mpa |
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Pressure resolution | 0.1MPa |
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Pressure measurement accuracy | 1% of indicated value |
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Ramp-up rate | Maximum 5.5GPa/s | Rapid voltage rise |
0~50MPa/min | Constant speed boost |
Atmosphere manufacturers provide | atmosphere | Steam, inert gas, etc. can be passed through, and the outer wall of the fuel rubber cladding tube is in a steam or inert gas environment |
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Steam pressure | Atmospheric pressure |
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Steam flow rate | 0-20cm/s |
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Other notes: |
1. The atmosphere is the external environment of the outer surface of the cladding sample tube. Tests can be carried out under water vapor and inert atmosphere; |
2. Install a steam flow measuring instrument to measure the steam flow (flow rate); |
3. Able to realize automatic/manual control of the test device; |
4. Equipped with a computer. It can automatically record the data required for the test. The recording format is EXCEL or TXT format; |
5. Reserve other atmosphere interfaces for subsequent modification of the test equipment: |
6. There are observation windows on both sides of the furnace. The sample tube is located in the center of the observation window. |
(Constant pressure rapid temperature rise test)
name | parameter | Remark |
Constant pressure rapid heating test indicators | Sample | Cladding sample material | See Table 1 |
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Cladding sample length | 200mm≤ L ≤320mm |
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Sample quantity per time | ≥1 |
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Cladding tube connection method | One end is connected to the pressure source. The other end is a slip seal or is also connected to the pressure source. And ensure that the cladding tube is not restricted by load in the axial direction. (Consider that the pressure source end is fixed and the other end is suspended) |
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High temperature furnace
high temperature manufacturers provide | High temperature furnace heating capacity | The heating furnace should have the ability to heat the sample to 600°C | The high temperature furnace is used to provide the initial temperature of the cladding tube. Other technical means can also be used to achieve this effect without using a high temperature furnace. |
Temperature control method | Three-point temperature control or better |
Temperature zone size | Ensure that the high temperature furnace uniform temperature zone can cover the cladding sample |
Temperature fluctuation in the uniform temperature zone | ±0.5%FS |
Temperature gradient in uniform temperature zone | 0.5%FS |
Temperature resolution | 0.5℃ |
High temperature furnace cooling rate | 5-10℃/min or better | Average value over a period of time |
The cladding heating method
is provided by the high temperature manufacturer | Shell heating method | Unlimited |
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Heating rate | 0-200℃/s (or better), the faster the heating rate, the better. Until the pipe fails |
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Cladding temperature measurement method | Thermocouple contact measurement | Non-contact measurement |
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Temperature measurement method | Three-point measurement | Midpoint measurement |
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Temperature measurement resolution | ≤0.5℃ | ≤1℃ |
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Temperature measurement accuracy | 1% of indicated value | 2% of indicated value |
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Cladding temperature measurement method | Use contact measurement whenever possible. If contact measurement has technical difficulties, consider using non-contact measurement. |
Stressors | Pressure medium | Gas or liquid |
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Cladding tube pressure range | Any value within 0-70Mpa is stable |
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Pressure resolution | 0.1MPa |
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Pressure accuracy | 1% of indicated value |
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Other notes: |
1. Able to realize automatic/manual control of the test device; |
2. Equipped with a computer, it can realize automatic recording of the data required for the test in the form of EXCEL or TXT format; |
3. Reserve other atmosphere ports for subsequent modification of the test equipment; |
4. There are observation windows on both sides of the furnace. The sample tube is located in the center of the observation window. |
