Fluid-Filled Neutron Absorber Tubes for Reliable Reactor Control
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Solution Overview
Problem
Conventional control rods in nuclear reactors face issues with reliability, maintenance complexity, space inefficiency, and high cost due to their design, which can lead to safety risks and operational challenges.
Innovation Solution
A reactor control system using hollow tubes filled with neutron-absorbing material, where the fluid level is controlled by a pump based on reactor reactivity, allowing for flexible reactivity control and independent control of different core portions, reducing the need for complex mechanisms and space-consuming components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional control rods are used to control reactor start up, shut down and power output, then reactor control function is achieved, but safety risks increase due to control rods becoming stuck or encountering excessive friction
Solution Approach 1:
The patent replaces the mechanical control rod system with a fluid-based system. Hollow tubes containing neutron-absorbing material are filled or emptied of fluid to control reactivity, eliminating mechanical moving parts that can stick or friction. The fluid (liquid metal or gas) is pumped into or out of the tubes to adjust neutron absorption, providing reliable control without mechanical contact.
Solution Approach 2:
The patent uses hydraulic or pneumatic principles by pumping fluid into or out of hollow tubes to control the position of neutron-absorbing material. The fluid pressure and flow rate control the filling level of the tubes, which in turn controls the reactivity of the reactor core, replacing mechanical rod movement with fluid pressure control.
2Reliability
If multiple control rods are added to offset single rod failure, then safety reliability improves, but device complexity and cost increase
Solution Approach 1:
The fluid-filled tube system serves multiple functions: it can control reactor startup, shutdown, and power output adjustment using the same basic mechanism. The system provides inherent safety through passive fluid drainage capabilities and eliminates the need for separate backup control rod systems, reducing overall system complexity while maintaining high reliability.
3Speed
If control rods are used for emergency shutdown (SCRAM), then rapid shutdown capability is achieved, but mechanism complexity increases due to spring loaded mechanisms and pressurised fluid storage
Solution Approach 1:
The system provides passive safety through automatic fluid drainage. In an emergency, the fluid automatically drains from the hollow tubes through gravity or pressure differential, causing rapid neutron absorption and shutdown without requiring active mechanical ejection mechanisms, spring-loaded systems, or complex pressurized fluid storage devices.
4Ease of operation
If conventional control rod assemblies are installed, then reactor control function is achieved, but space utilization decreases due to large surface area and multiple welds
Solution Approach 1:
The invention extracts the neutron-absorbing material from a large mechanical control rod structure and places it in compact hollow tubes. The fluid-filled tubes have much smaller volume and surface area compared to conventional control rod assemblies, reducing the space required in the reactor core while maintaining full control capability through fluid level adjustment.
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 system enhances reactor safety, simplifies maintenance, reduces costs, and optimizes space utilization by providing a more reliable and efficient means of controlling neutron flux without the limitations of traditional control rods.
Implementation Method 1
one or more hollow tubes (220) comprising neutron absorbing material
Implementation Method 2
a pump connected to the first end of each hollow tube and operable to control the amount of a first fluid within the hollow tube
Implementation Method 3
the first fluid comprising a neutron moderator
Data Source
AI summary
A reactor control system for a nuclear reactor, the reactor control system comprising: one or more hollow tubes comprising neutron absorbing material, each having a first end and a second end; a pump connected to the first end of each hollow tube and operable to control the amount of a first fluid within the hollow tube, the first fluid comprising a neutron moderator, wherein: the pump is controlled based on a level of reactivity in the nuclear reactor, and the second end of the hollow tubes is in fluid communication with a second fluid, the second fluid having a neutron moderating capacity lower than 10% of that of the first fluid.