Telescoped Control Rod for Pebble-Bed Reactor Shutdown
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing modular pebble-bed high-temperature gas-cooled reactor relies on complex and operationally challenging absorption sphere shutdown systems, which complicate reactivity control and increase the risk of accidents, especially when only a control rod system is used for cold shutdown.
Innovation Solution
A telescoped control rod system comprising an inner and outer rod with a guide cylinder assembly, allowing for extended reach within the reactor core without altering the pressure vessel height, and incorporating multi-section structures with shock absorbers and articulated joints for improved reliability and ease of operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a control rod system is used for cold shutdown, then reactivity control is enhanced, but the control rod requires huge driving force to overcome resistance of stacked spherical fuel elements causing damage to fuel elements
Solution Approach 1:
The control rod is divided into multiple sections (first control rod section, second control rod section, etc.) that can move independently. This segmentation allows each section to be optimized for its specific function and reduces the overall driving force required compared to a single long control rod, while maintaining effective reactivity control throughout the reactor core.
Solution Approach 2:
The control rod sections are arranged in a nested configuration where inner control rod sections are positioned within outer control rod sections. This nested structure allows the control rod to achieve extended reach into the reactor core without increasing the external dimensions, reducing the driving force required while maintaining full reactivity control capability.
2Reliability
If the length of absorber of each control rod is increased to cover entire reactor core, then reactivity control is improved, but the height of reactor pressure vessel must be increased
Solution Approach 1:
The nested arrangement of control rod sections allows the absorber length to extend throughout the entire reactor core height while the external dimensions of the control rod assembly remain compact. This enables full reactivity control coverage without increasing the reactor pressure vessel height.
Solution Approach 2:
The control rod sections are designed to move dynamically and independently, allowing the absorber length to be effectively extended into the reactor core without requiring a proportional increase in the stationary pressure vessel height. The dynamic movement enables full core coverage with compact external dimensions.
3Reliability
If absorption sphere shutdown system is used, then cold shutdown is achieved, but system complexity increases and operation difficulty increases
Solution Approach 1:
The control rod system is designed to perform multiple functions: it provides reactivity control during operation and also achieves cold shutdown when needed. This multi-functionality eliminates the need for a separate absorption sphere shutdown system, reducing overall system complexity while maintaining both reactivity control and cold shutdown capabilities.
Solution Approach 2:
The control rod system merges the functions of reactivity control and shutdown into a single integrated system. By combining these functions, the patent eliminates the need for separate absorption sphere shutdown system components, thereby reducing system complexity and operational difficulty while maintaining reliable cold shutdown capability.
4Ease of operation
If control rod system is simplified to reduce complexity, then ease of operation is improved, but reactivity control capability may be reduced
Solution Approach 1:
The control rod is segmented into multiple independent sections that can be controlled separately. This segmentation maintains fine-grained reactivity control capability while simplifying the overall system architecture and operation compared to a single complex control rod system, as each section can be independently adjusted for precise reactivity management.
Data Source
AI summary
A reactor lateral reflection layer telescoped control rod capable of separately achieving cold shutdown includes an inner rod, an outer rod and a guide cylinder assembly which are vertically and coaxially arranged, wherein the outer rod and the guide cylinder assembly are hollow cylindrical bodies; the top end of the inner rod can move up and down inside the outer rod and the other end of the inner rod moves up and down, along with the top end, inside a control rod passage which is positioned below the guide cylinder assembly and is coaxial with the guide cylinder assembly; and the top end of the outer rod can move up and down in the guide cylinder assembly and the other end of the outer rod moves up and down, along with the top end, inside the control rod passage.