Nuclear Reactor Coolant Segmentation for Corrosion and Maintenance
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Solution Overview
Problem
Current nuclear reactors with liquid-metal coolants face issues such as the unavailability of materials resistant to high temperatures and corrosion, complex maintenance due to high reactor cover temperatures, and the need for simultaneous replacement of pumps and steam generators, which complicates repairs and can lead to reactivity failures.
Innovation Solution
The design separates the steam generators and pumps into independent structures within an annular space, allowing for independent replacement and operation, with a coolant circulation pattern that uses a cold collector to reduce temperature and prevent moisture entry into the core, and includes features like bypass valves and radial partitions to manage coolant flow and reduce hydraulic resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the pump transfers hot coolant at approximately 500°C, then heat exchange efficiency is improved, but material corrosion and erosion resistance becomes unavailable
Solution Approach 1:
The reactor is divided into two separate shells: a first shell containing the core and hot coolant circulation, and a second shell containing the pump and steam generator with cold coolant circulation. This segmentation allows the pump to handle cold coolant while the hot coolant flows through the core and steam generator, resolving the contradiction between heat exchange efficiency and material durability.
Solution Approach 2:
The pump is extracted from the hot coolant environment and placed in the cold coolant circulation system. The pump takes cold coolant from the lower part of the steam generator and delivers it to the core, while the hot coolant circulation path is separated into the first shell, eliminating material exposure to both high temperature and high velocity simultaneously.
2Temperature
If the reactor cover is operated at high temperature approximately 500°C, then heat transfer is improved, but maintenance and cooling of pump bearings and electric drive becomes complicated
Solution Approach 1:
The reactor cover area is segmented into two temperature zones: the first shell region exposed to hot coolant for heat transfer, and the second shell region containing the pump and steam generator operated with cold coolant. This allows pump bearings and electric drive to be located in the cold zone, simplifying maintenance and cooling while maintaining effective heat transfer in the hot zone.
3Device complexity
If the pump and steam generator are unitized into a single inseparable assembly, then structural compactness is improved, but repairs become complicated requiring simultaneous replacement
Solution Approach 1:
While the pump and steam generator are positioned close together in the second shell for structural compactness, they are designed as separate, independently replaceable units. The pump can be removed and replaced without disturbing the steam generator, and vice versa, resolving the contradiction between compactness and repairability.
4Use of energy by moving object
If steam bubbles and water drops are entrained by coolant falling flow, then steam generator heating is improved, but reactivity failure of fast neutron spectrum reactor may occur
Solution Approach 1:
The coolant circulation is segmented into distinct paths: cold coolant flows upward through the pump to the core, and hot coolant flows separately through the steam generator. This separation prevents steam bubbles and water drops from being entrained in the coolant flow to the core, maintaining reactivity stability while still achieving effective steam generator heating through the separated hot coolant path.
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
This design enhances the reliability and performance of the reactor by reducing corrosion and erosion risks, simplifying maintenance, allowing independent replacement of components, and preventing moisture entry, thus improving operational safety and reducing repair times and costs.
Implementation Method 1
a pump (4) for circulating a primary circuit coolant through the core (2)
Implementation Method 2
a core (2) comprising a bundle of fuel elements and submerged into a primary coolant circulating between the core
Implementation Method 3
at least one steam generator (3) in which a primary circuit coolant moves in a tube space
Data Source
AI summary
A nuclear reactor with a liquid metal coolant includes a housing having a separating shell disposed therein. In the annular space between the housing and the separating shell are disposed at least one steam generator and at least one pump. Inside the separating shell there is an active region, above which a heat collector is disposed. The heat collector is in communication with the vertically central portion of the steam generator in order to separate a stream of liquid metal coolant into ascending and descending flows. Alternatively, the heat collector is in communication with the upper portion of the steam generator in order to create a counter-flow heat exchange regime. Below the reactor head is an upper horizontal cold collector with an unfilled level of coolant, and below the steam generator is a lower accumulating collector in communication with the upper cold collector.