Nuclear Reactor Electrical Penetration Assembly with Anti-Ejection Seal
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Solution Overview
Problem
Existing electrical penetration assemblies for nuclear reactor vessels face challenges in being rapidly demountable, compatible with differential expansions, and ensuring significant usable diameters for electrical connections while maintaining safety and preventing primary leaks, as existing solutions either increase the second containment barrier or use non-ductile materials like glass or ceramic that are insufficient for primary pressure conditions.
Innovation Solution
An electrical penetration assembly with a penetration body having a sealed connector and unitary feed-throughs individually insulated by ceramic or prestressed vitroceramic, an anti-ejection device, and a detection system for leak-tightness failure, which separates the connection function from the second containment barrier, using different materials for seals and insulators to enhance safety and prevent primary leaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a dedicated demountable instrumentation flange with multiple thimbles is installed within the vessel, then rapid demountability and compatibility with differential expansions are improved, but the extension of the second containment barrier increases considerably
Solution Approach 1:
The electrical penetration assembly is divided into separate functional components: a first seal (hermetic seal) and multiple second seals (individual insulators for each feed-through). This segmentation allows the connection function to be separated from the containment barrier function, enabling rapid demountability while avoiding extension of the second containment barrier.
Solution Approach 2:
The invention extracts the connection function from the second containment barrier by introducing a first seal that hermetically seals the penetration body at the first end, separate from the individual insulators forming second seals. This extraction allows the penetration assembly to be rapidly demounted without compromising the second containment barrier.
2Strength
If hermetic electrical feed-through technologies (prestressed vitroceramic or brazed ceramic) are used for containment envelope penetrations, then temperature and pressure stress resistance is improved, but the ductility and toughness characteristics required for second containment barrier materials are not met
Solution Approach 1:
Different materials are used for different functions: the first seal uses a hermetic sealing material resistant to temperature and pressure stresses, while the second seals (individual insulators) use ceramic or prestressed vitroceramic materials providing electrical insulation. This local quality differentiation allows each component to be optimized for its specific function while meeting overall safety requirements.
Solution Approach 2:
The electrical penetration assembly employs composite material construction with a penetration body, first seal with hermetic sealing, and individual insulators made of ceramic or prestressed vitroceramic. This composite approach combines materials with complementary properties to achieve both mechanical strength under pressure/temperature and electrical insulation.
3Reliability
If glass, vitroceramic or ceramic connectors are used for electrical feed-throughs, then electrical insulation is improved, but the non-ductile and brittle character makes direct use difficult on the perimeter of the second regulatory barrier under primary pressure
Solution Approach 1:
The electrical insulation function is segmented into multiple individual insulators, one for each feed-through, rather than using a single continuous ceramic or glass connector. This segmentation allows each insulator to be independently manufactured and installed, reducing the overall complexity and improving manufacturability while maintaining electrical insulation performance under primary pressure conditions.
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
The solution effectively prevents primary leaks and limits leakage rates in case of failure, ensuring safety and compliance with design regulations by using a double hermetic seal and anti-ejection system, while allowing for easy connection and disconnection of the sealed connector, reducing the need for frequent inspections.
Implementation Method 1
each unitary electrical feed-through allowing a single electrical conductor to pass therethrough thereby ensuring the continuity of the electrical connections, each unitary electrical feed-through being individually insulated by an individual insulator
Implementation Method 2
a sealed electrical connector forming a first seal for the electrical penetration assembly, said sealed electrical connector hermetically sealing the penetration body at the first end; each unitary electrical feed-through being individually insulated by an individual insulator forming a second seal for the electrical penetration assembly, said unitary electrical feed-throughs hermitically sealing the penetration body at the second end
Data Source
AI summary
An electrical penetration assembly for a nuclear reactor vessel, mountable in an aperture of a nuclear reactor vessel, includes a penetration body including first and second ends to be positioned, respectively, inside and outside the vessel; a sealed electrical connector providing a first seal for the electrical penetration assembly, the sealed connector insulating the penetration body at the first end; a feed-through carrier flange having a plurality of unitary electrical feed-throughs, each unitary feed-through allowing a single electrical conductor to pass therethrough, thereby ensuring continuity of the electrical connections, each unitary feed-through being individually insulated by an individual insulator providing a second seal, the unitary feed-throughs insulating the penetration body at the second end; and an anti-ejection device formed by the engagement between a narrowed portion provided at each unitary feed-through and a shoulder that is larger than the narrowed portion and provided on each of the electrical conductors.