Removable Annular Seal Ring for Nuclear Reactor Penetration
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Solution Overview
Problem
In small modular nuclear reactors, the conventional control rod drive mechanisms and instrumentation routing through vessel penetrations are hindered by high temperatures and in-vessel immersion, making traditional cable routing unreliable and inaccessible, especially during refueling and maintenance.
Innovation Solution
A removable annular seal ring with radial passages and thermal expansion matching materials, allowing for secure and reliable transmission of utilities like electrical power and instrumentation signals through an annular penetration flange between the reactor vessel and closure flanges, facilitating disassembly, inspection, and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cable routing through vessel penetrations is used, then utilities can be transmitted to internal components, but the routing becomes inaccessible and unreliable during refueling and maintenance operations
Solution Approach 1:
The invention divides the utility transmission system into two independent pathways: permanent penetrations through the vessel head for continuous utilities, and removable penetrations through the flange for utilities requiring access during maintenance. This segmentation allows each pathway to be optimized for its specific function, resolving the contradiction between reliability and accessibility.
Solution Approach 2:
The flange penetration assembly is designed to be dynamically configurable - penetrations can be installed, removed, or reconfigured based on operational needs. This dynamic capability allows the system to transition between permanent sealed state during operation and accessible state during maintenance, eliminating the fixed compromise of conventional designs.
2Stability of the object's composition
If traditional penetration methods are used, then vessel integrity is maintained, but disassembly and reassembly during refueling are impeded
Solution Approach 1:
The penetration system is segmented into permanent integrally formed penetrations in the vessel head and removable penetrations in the flange. This allows the vessel head to maintain its structural integrity and pressure boundary function, while the flange penetrations can be independently removed to facilitate refueling operations without compromising vessel stability.
Solution Approach 2:
The penetrations requiring frequent access are extracted from the permanent vessel head structure and relocated to the removable flange assembly. This extraction allows maintenance personnel to remove and service these penetrations during refueling without disassembling the vessel head or compromising the pressure boundary, thus improving refueling efficiency while maintaining vessel integrity.
3Stability of the object's composition
If high temperature materials are used for penetration components, then thermal expansion matching is achieved, but manufacturing complexity increases
Solution Approach 1:
The flange and penetration components are fabricated from high temperature materials specifically where thermal exposure occurs (in the flange and penetration bodies), while other portions of the reactor system can use conventional materials. This localized application of high temperature materials achieves thermal expansion compatibility where needed without unnecessarily increasing manufacturing complexity across the entire system.
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 reliable and accessible routing of utilities within the reactor vessel, maintaining pressure integrity and facilitating reactor operations, refueling, and maintenance without impeding vessel disassembly or compromising safety.
Implementation Method 1
The reactor vessel is pressurized to a high internal pressure, and the control rod drive mechanisms are housed in part in pressure housings that are tubular extensions of the reactor pressure vessel
Implementation Method 2
A removable annular seal ring with radial passages and thermal expansion matching materials, allowing for secure and reliable transmission of utilities
Data Source
AI summary
A nuclear reactor having a penetration seal ring interposed between the reactor vessel flange and a mating flange on the reactor vessel head. Radial ports through the flange provide passage into the interior of the reactor vessel for utility conduits that can be used to convey signal cables, power cables or hydraulic lines to the components within the interior of the pressure vessel. A double o-ring seal is provided on both sides of the penetration flange and partial J-welds on the inside diameter of the flange between the flange and the utility conduits secure the pressure boundary.