Nuclear Reactor Absorber Element Assembly With Butt Resistance Welding
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Solution Overview
Problem
The existing method of assembling absorber elements for pressurized water reactors is inefficient due to lengthy argon-arc welding processes, which can lead to reduced pressure inside the elements, air penetration, and potential leaks, affecting the reliability and operational capacity of the components.
Innovation Solution
The method involves using butt resistance welding (BRW) to pressurize the upper nozzle and can, combined with a spring plunger to secure the absorbing materials, reducing welding time and eliminating the need for an adulterant within the can, thereby enhancing the structural integrity and leakproofness of the absorber elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If argon-arc welding is used to pressurize the upper nozzle and can, then the welding connection is achieved, but the welding time is long causing pressure decrease and air penetration
Solution Approach 1:
The patent replaces the thermal welding process (argon-arc welding) with a mechanical fastening system consisting of a clamp, compression element, and sealing element. This mechanical substitution eliminates the need for prolonged thermal welding, significantly reducing assembly time while maintaining leakproofness through the compression-induced seal between the clamp and the can body.
2Reliability
If argon-arc welding is used for pressurization, then welding connection is established, but pressure inside AE decreases and air penetration occurs
Solution Approach 1:
The patent applies preliminary action by pre-assembling the clamp, compression element, and sealing element around the upper nozzle and can assembly before final installation. The sealing element is positioned in advance to ensure immediate sealing upon compression, preventing air penetration during the entire assembly and installation process rather than relying on post-welding sealing.
Solution Approach 2:
The patent introduces a sealing element as an intermediary component between the compression element and the can body. This sealing element acts as a mediator that prevents direct contact between air and the internal cavity during assembly, effectively blocking air penetration without requiring prolonged welding to achieve sealing.
3Reliability
If adulterant is placed inside the can, then welding current bridging is prevented, but can length increases reducing strength and rigidity
Solution Approach 1:
The patent extracts the adulterant from the internal cavity of the can and relocates it to the upper nozzle assembly. This extraction eliminates the need for the adulterant to be inside the can, thereby maintaining can length and preserving structural strength and rigidity, while still preventing welding current bridging through the upper nozzle's conductive components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces the welding time, increases the strength and rigidity of the absorber elements, and improves their reliability and operational capability by minimizing the risk of leaks and air penetration during assembly.
Implementation Method 1
a spring plunger, which provides claimed effect
Implementation Method 2
butt resistance welding (BRW) of upper nozzle and can
Data Source
Figure 1
Figure 2
AI summary
Invention relates to nuclear engineering, in particular, to method of assembling absorber elements (AE) of pressurized water reactor control and protection systems , e.g., VVER-1000 , AES-2006 and others. There is offered the method of assembling nuclear reactor absorbing element, including preparation of can in form of tube, its pressurization from one edge by means of bottom nozzle having conic shape, loading of can by absorbing materials in form of pellets or powder, fastening of absorbing material from axial displacement with spring plunger, pressurization of a can from another edge by means of upper nozzle comprising ballast, characterized in that welding of bottom nozzle with can is performed with argon-arc welding, and pressurization of AE is performed with upper nozzle by means of butt resistance welding, wherein during latest operation an internal cavity of can is vacuumed and filled with indifferent gas. Method of assembling nuclear reactor absorbing element, wherein the can pressurization is performed by means of nozzles made from same material as can, e.g. 42XHM alloy. The said change of assembly method allows to increase reliability and operating capacity of AE while saving its efficiency.