Device for triggering and inserting absorbing members and/or mitigators in fissile area of nuclear reactor and nuclear fuel assembly comprising the device

Abstract

A system for triggering and inserting a neutron absorber and / or mitigator (2) in a fissile area of a nuclear reactor is disclosed. The trigerring and inserting system is intended to be mounted in a nuclear fuel assembly wherein there flows a coolant. The system comprises a capsule (10) provided with holding means (11) for securing the absorber (2) in a non-inserted position; a stop surface (24) forming means for locking the holding means (11); and a thrust surface (26) forming means for releasing the absorber. The surfaces are carried by a control head (18). A collet (19) expands longitudinally differentially with regard to the capsule (10) under the effect of an increase in the temperature of the coolant and moves the surfaces (24, 26) such that the stop surface is moved away from the holding means at the normal operating temperature of the reactor, and the thrust surface (26) releases the absorber at a threshold temperature.

Description

technical field [0001] The invention relates to an independent triggering and insertion device for at least one element to be inserted. The elements to be inserted may only be absorbing material and / or moderator in case the overall core melts. A moderator is a material capable of forming a eutectic with a low melting point with the material forming the cladding of the nuclear fuel rods in the assembly, and the moderator prevents the formation of plugs that would prevent the evacuation of the molten core or the removal of the molten core from the core of a nuclear reactor. core melt and / or moderator absorption. [0002] The self-contained triggering and insertion device is especially useful in sodium-cooled fast reactors (SFR) and nuclear fuel assemblies comprising the device. Background technique [0003] In order to control the core activity of the reactor and limit the consequences of a failure of the reactor, it is planned to insert elements comprising neutron absorbing...

AI Technical Summary

Problems solved by technology

[0011] Firstly, the mechanism consists of several parts that are hinged to each other, thus increasing the risk of wedging (for example, by jamming), which does not contribute to the reliability of the control rod being triggered

Additionally, clearance must be provided at the swivel hinge

There is therefore a risk of the control rod being accidentally inserted, for example the hook can pivot sufficiently under the effect of shocks or vibrations during handling

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