Nuclear Reactor Core Support Structure for Heat Exchanger Space
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Solution Overview
Problem
Existing fast nuclear reactors face challenges in achieving compact design with integrated heat exchangers and pumps due to the inability to house them vertically within the core, compromising reactor compactness and safety.
Innovation Solution
A support structure that axially and radially constrains the core using upper and lower supports, allowing space for a heat exchanger above the core and incorporating elastic radial containment systems with bimetallic expanders for fuel elements to ensure safety and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the core is supported by a single support structure from below, then the structure is simple, but the space above the core is not available for heat exchangers
Solution Approach 1:
The support structure is segmented into two distinct parts: an upper support carrying the upper portion of the core and a lower support carrying the lower portion of the core. This segmentation allows the space above the core to be available for heat exchangers while maintaining structural support functionality.
Solution Approach 2:
The support system transitions from a single vertical support from below to a distributed support system with upper and lower supports positioned at different vertical levels, creating available space in the upper region for heat exchanger integration.
2Productivity
If fuel elements are closely spaced to maximize core density, then productivity is improved, but safety is compromised in case of excessive heating
Solution Approach 1:
The elastic radial containment system with bimetallic expanders is pre-configured to automatically act against the fuel elements when excessive heating occurs, forcing them apart before a safety incident can develop. The bimetallic strips are pre-loaded in a compressed state ready to expand and push fuel elements radially outward.
Solution Approach 2:
Bimetallic expanders utilizing differential thermal expansion of two metals are employed to detect and respond to temperature increases. When the core temperature exceeds the design value, the bimetallic strips expand differentially, triggering the radial expansion mechanism that spaces out the fuel elements.
3Strength
If support structures are placed in high neutron flux zones, then core support is effective, but neutron radiation damage increases
Solution Approach 1:
The core support function is extracted from the high neutron flux zone by positioning the upper and lower supports at the ends of the core where the neutron flux is lower, thereby reducing neutron radiation damage to the support structures while maintaining effective core support.
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 compact reactor design with integrated heat exchangers and pumps, enhancing safety by spacing fuel elements during excessive heating and ensuring efficient cooling, thus reducing neutron radiation exposure.
Implementation Method 1
The upper support is provided with an elastic radial containment system for the heads of the fuel elements
Implementation Method 2
characterized by the mechanical coupling of high thermal expansion elements which engage alternatively with low thermal expansion elements to amplify the radial expansion of respective end elements
Implementation Method 3
the mechanical coupling of high thermal expansion elements which engage alternatively with low thermal expansion elements
Implementation Method 4
the upper support is carried by a support structure which, inside the reactor vessel, extends from the roof of the reactor
Data Source
AI summary
A nuclear reactor is disclosed. The nuclear reactor comprises a vessel closed at the top by a roof and housing a core, comprising a bundle of fuel elements. The core being supported by a lower support supporting a lower portion of the core below an active zone of the fuel elements; and an upper support supporting an upper portion of the core above the active zone of the fuel elements; the upper support is joined to the roof by a support structure extending from the roof and has an end element centrally open and internally provided with a plurality of jaws for vertical support and elastic radial constraint of the fuel elements.