Segmented Moderator Repair Element for Graphite Block Groove Cutting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In gas-cooled nuclear reactors, graphite blocks experience unpredictable spatial expansion leading to stress and damage, particularly at edges, which can result in graphite spalling into the annular gap, causing cooling issues or blockage of fuel elements, and existing technologies do not provide a method for repairing such damage.
Innovation Solution
A moderator repair element comprising cutting elements and spacer elements arranged in a first and second imaginary circle, allowing for precise removal and replacement of damaged graphite, with cutting elements having drive connections for rotation and radial movement to form a groove, and spacer elements fitting between cutting elements to form a form-fitting connection, ensuring structural integrity and adaptability to temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If graphite blocks are used as moderator in gas-cooled nuclear reactors, then neutron moderation is achieved, but graphite undergoes spatial expansion and stress leading to damage and spalling
Solution Approach 1:
The damaged graphite material is removed from the graphite block using cutting elements that cut a groove around the damaged area. The spalled graphite is extracted from the annular gap to prevent cooling deterioration and fuel element blockage.
Solution Approach 2:
The cutting groove is formed around the damaged area before the repair element is inserted. This preliminary action prepares the space for receiving the repair element made of graphite-like material, ensuring proper fit and structural integrity.
2Ease of repair
If cutting elements are moved radially outward to form groove, then damaged graphite can be removed, but device complexity increases with multiple drive mechanisms
Solution Approach 1:
The drive mechanism serves multiple functions: it rotates the cutting elements for groove formation, moves them radially outward for cutting, and positions them for repair element insertion. This multi-functionality reduces the number of separate drive mechanisms needed.
Solution Approach 2:
The cutting elements are designed with radial movability, allowing them to transition between retracted and extended positions. This dynamic capability enables the cutting elements to adapt their position during different phases of the repair operation without requiring separate mechanisms.
3Stability of the object's composition
If spacer elements are inserted between cutting elements, then structural stability is improved, but manufacturing precision is required for form-fitting connection
Solution Approach 1:
The repair element is segmented into multiple spacer elements that are inserted between the cutting elements. Each spacer element can be manufactured separately and then assembled, allowing for controlled precision in each component while maintaining overall structural stability through the distributed arrangement.
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
Enables effective repair of graphite damage during operation or shutdown, maintaining reactor integrity by removing and replacing damaged graphite, ensuring mechanical stability and minimizing disruption to neutron flow and thermal efficiency.
Implementation Method 1
the cutting elements have cutting means on their radially outward-pointing surfaces... the cutting elements can be set in rotation via their drive connection means, so that the cutting means gradually remove graphite and thus form the groove
Implementation Method 2
The first and second connecting means are positively connected when the cutting elements and spacer elements are arranged in the second array... ensuring structural integrity and adaptability to temperature changes
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a moderator repair element (10) for a graphite body arrangement serving as a moderator in a gas-cooled nuclear reactor. The moderator repair element (10) is characterized in that cutting elements (12) and spacer elements (24) are arranged on an imaginary plane around an imaginary central axis in a first arrangement (11) within a first imaginary circle, that the cutting elements (12) have cutting means on their radially outwardly facing surfaces, that the cutting elements (12) have drive connection means for connection to a drive on their radially inwardly facing surfaces, that the cutting elements (12) have first connection means on their radially oriented surfaces, and that the spacer elements (24) have second connection means on their radially oriented surfaces.Furthermore, the cutting elements (12) are movable radially outwards to a predetermined position, and this predetermined position is such that the spacer elements (24) can be inserted between two radially adjacent cutting elements (12). The spacer elements (24) are movable radially and/or axially outwards, or outwards and axially to a further position, and in this further position, the spacer elements (24) are inserted between two radially adjacent cutting elements (12). The cutting elements (12) are also arranged in the predetermined position, and the inserted spacer elements (24) are arranged in a second arrangement (46) within a second imaginary circle. Finally, the first and second connecting elements are positively connected when the cutting elements (12) and spacer elements (24) are arranged in the second arrangement (46).The invention also relates to a moderator repair element tool and tool system with which the moderator repair element (10) can be mounted.