Submersible Vehicle Support Arms for Deflected PWR Fuel Elements
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Solution Overview
Problem
Bent or twisted fuel assemblies in pressurized water reactors pose challenges during centering and handling, as they can prevent the fuel element loading machine from functioning properly, requiring time-consuming manipulations and obstructing the use of conventional fuel assembly loading machines.
Innovation Solution
A submersible vehicle with adjustable support arms and mandrels allows for the manipulation of fuel elements by exerting forces transverse to their axial direction, creating space for easy loading or unloading by pushing or pulling fuel assemblies into alignment, thereby facilitating the handling of deflected fuel elements without the need for complex manipulator installations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional fuel element loading machines with centering pins are used, then centering is possible when fuel assemblies are properly aligned, but the machine cannot handle bent or twisted fuel assemblies
Solution Approach 1:
The fuel assembly handling system is divided into multiple independent support arms (first and second support arms) that can operate separately. Each support arm can be independently adjusted to accommodate different fuel assembly positions and orientations, allowing the system to handle both straight and deflected fuel assemblies without requiring a completely redesigned centering mechanism.
Solution Approach 2:
The support arms are designed with adjustable positioning capabilities, allowing them to move and adapt to different fuel assembly configurations. The arms can be positioned at different locations along the fuel assembly and adjusted to compensate for bends and twists, transforming a static centering system into a dynamic one that can accommodate various fuel assembly states.
2Reliability
If fuel assemblies are bent or twisted, then plastic deformation occurs due to thermal expansion anisotropy or cooling water interaction, but the fuel assemblies cannot be properly centered or loaded
Solution Approach 1:
The support arms act as intermediary elements between the fuel assembly loading machine and the deflected fuel assemblies. These arms provide a flexible interface that can accommodate the plastic deformation of fuel assemblies while still enabling reliable loading. The support arms transmit forces and positioning adjustments to the fuel assemblies without requiring direct rigid contact, thereby maintaining reliability while improving ease of operation.
3Ease of operation
If support arms are used to push or pull fuel assemblies into alignment, then deflected fuel assemblies can be positioned correctly, but the loading process becomes more complex
Solution Approach 1:
The support arms are designed to perform multiple functions: they provide structural support for the fuel assemblies, enable positioning adjustments for deflected assemblies, and facilitate the loading process. By combining these functions into a single versatile mechanism, the system improves ease of operation without proportionally increasing device complexity, as the same structural elements serve multiple purposes.
Data Source
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AI summary
The invention relates to a method for loading and unloading a core of a pressurised water reactor. According to said method, a force (F) acting transversally to the axial direction (57) of a fuel element (50) of the core is exerted against said fuel element (50), which is adjacent to an unloading or loading fuel element position (52), in an upper region of the fuel element (50), by means of a device. The device used is a submersible vessel (2) that can be freely manoeuvred under water, and on which an extensible carrier arm (22, 24) is arranged, said arm being at least indirectly positioned against the fuel element (50).