Experimental device and method for studying the failure behavior of fuel elements under severe nuclear reactor accidents

Abstract

An experimental device and method for studying the failure behavior of fuel elements under severe nuclear reactor accidents, the experimental device includes an upper electrode cooling chamber, a middle cylinder, a lower electrode cooling chamber, a simulated fuel rod and a tensile testing machine; the middle cylinder contains Multiple heat shielding devices, which can heat the cladding to above 2200°C, carry out single fuel rods or fuel rods under severe accident conditions caused by nuclear reactor coolant loss accidents, reactivity introduction accidents, and accident mitigation measures such as core water injection The invention also provides an experimental method; the invention discloses the failure mechanism of the fuel element by carrying out the failure behavior experiment of the fuel element under a severe nuclear reactor accident, which has important guiding significance for the safety design of the nuclear reactor.

Description

technical field [0001] The invention relates to the technical field of nuclear reactor fuel performance testing, in particular to an experimental device and method for studying the failure behavior of fuel elements under severe nuclear reactor accidents. Background technique [0002] Fuel elements are the core components of nuclear reactor operation, and their failure behavior under severe accidents is the key content of nuclear reactor safety research. Severe accidents in nuclear reactors can be caused by various accidents, and the failure mechanisms of fuel elements are different under different accident conditions. For example, when a loss-of-coolant accident (Loss-Of-Coolant Accident, LOCA) occurs in a nuclear reactor, part of the fuel element is exposed to high-temperature water vapor, which cannot take away the heat released by the fission of uranium dioxide pellets in time. The temperature and internal pressure of the element increase, the cladding will creep and swe...

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Problems solved by technology

[0003] For example, literature (Kim J H, Lee M H, Choi B K, et al. Deformation of zircaloy-4 cladding during a LOCA transient up to 1200°C [J]. Nuclear engineering and design, 2004, 234(1-3): 157-164. ) discloses an experimental device for the failure behavior of Zr-4 alloy cladding under the LOCA accident. The cladding is directly heated by the method of clamping the cladding with electrodes, and there is no core block inside the cladding. Argon gas is used to pressurize the Zr-4 alloy. The failure behavior of the cladding in a water vapor environment; however, the experimental device can only heat the cladding to 1000-1250 °C, and cannot effectively heat the cladding of new materials such as SiC, and cannot completely cover the temperature range of severe accident conditions, and Unable to study the effect of fuel element pellets on cladding failure

[0004] For example, literature (Uetsuka H, ​​Furuta T, Kawasaki S. Zircaloy-4 cladding embrittlement due to inner surface oxidation under simulated loss-of-coolantcondition [J]. Journal of Nuclear Science and Technology, 1981, 18 (9): 705-717. ) also discloses a Zr-4 alloy cladding failure behavior experimental device under the LOCA accident, which uses a radiation furnace to heat the fuel element with pellets to study the failure behavior of the fuel element in a water vapor environment; but the experimental device adopts The radiation heating method cannot simulate the temperature gradient between the reactor fuel element pellets, air gap and cladding, and the double ends of the fuel element are sealed by welding, so the internal pressure cannot be flexibly controlled in the experiment. experiment

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