Suspended Upper Internals for Compact Nuclear Reactor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Compact nuclear reactor designs face challenges with the complexity, volume, and weight of upper internals, which complicate reactor refueling and maintenance, and introduce potential coolant drainage risks during abnormal events.
Innovation Solution
The design features a suspended support assembly with multiple hanger plates and tie rods that align and support internal control rod drive mechanisms and guide frames, allowing for the upper internals to be lifted as a unit during refueling, reducing disassembly needs and enhancing maintenance efficiency while minimizing vessel penetrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If upper internals are traditionally supported in compact nuclear reactors, then the reactor can operate, but the complexity, volume, and weight of upper internals increase, complicating refueling and maintenance
Solution Approach 1:
The upper internals are divided into multiple separable components including guide frames, control rod assemblies, and a suspended support assembly with hanger plates and tie rods. This segmentation allows each component to be independently positioned and installed, reducing overall complexity while enabling simplified refueling operations where components can be accessed and replaced systematically
Solution Approach 2:
The suspended support assembly introduces dynamic flexibility through the tie rod suspension system that allows the upper internals to be lowered and raised as a unified but flexible structure. This dynamic capability enables the internals to be positioned at different heights during operation and maintenance, simplifying refueling access without requiring complete disassembly
2Volume of stationary object
If upper internals are traditionally supported in compact nuclear reactors, then the reactor can operate, but the volume and weight of upper internals increase, requiring more vessel space
Solution Approach 1:
The guide frames are designed to nest around the control rod assemblies, with the suspended support assembly integrating both structures. This nesting arrangement minimizes the overall volume occupied by upper internals within the pressure vessel, creating a compact configuration that reduces vessel space requirements while maintaining functional complexity
Solution Approach 2:
The guide frames and control rod assemblies are merged into a single integrated suspended support structure that hangs from the pressure vessel head. This consolidation reduces the total volume required compared to separate support structures, while the combined design simplifies the overall system by reducing the number of independent components
3Reliability
If traditional upper internals support structures are used, then the reactor can operate, but the risk of coolant drainage during refueling increases
Solution Approach 1:
The suspended support assembly is designed with tie rods and hanger plates that pre-establish a secure hanging configuration from the pressure vessel head. This preliminary structural arrangement ensures that during refueling operations, the upper internals remain firmly positioned and supported, preventing accidental coolant drainage while allowing systematic access for fuel replacement
Solution Approach 2:
The dynamic suspension system allows the upper internals to be carefully lowered to access positions during refueling while maintaining secure support. This controlled movement capability enables refueling operations without compromising coolant retention, as the flexible suspension prevents sudden drops or mispositioning that could trigger drainage events
Data Source
AI summary
A pressure vessel comprises an upper vessel section and a lower vessel section. A nuclear reactor core comprises fissile material contained in a containing structure and disposed in the lower vessel section. Upper internals are disposed in the lower vessel section above the nuclear reactor core. The upper internals include at least guide frames and internal control rod drive mechanisms (CRDMs) with CRDM motors mounted on a suspended support assembly including a plurality of hanger plates connected by tie rods. The plurality of hanger plates includes a lowermost hanger plate having alignment features configured to align the upper internals with the containing structure that contains the nuclear reactor core.