Movable Neutron Reflector Moderator Blocks for Reactor Control
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Solution Overview
Problem
Current reactor designs lack a reliable and independent reactivity control system capable of controlling reactivity changes across all power levels, particularly for reactors other than Boiling Water Reactors and Pressurized Water Reactors, as they rely on manipulating water properties within the core, which is insufficient for diverse reactor types and power ranges.
Innovation Solution
The introduction of a reactor control system that modifies the physical geometry around the core using movable neutron reflector/moderator blocks, which can be positioned to adjust neutron coupling and reflection, providing a separate and distinct control mechanism in addition to the existing rod control system, applicable to all reactor types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If control rods are used for reactivity control, then the reactor can be controlled during normal operation, but the system lacks independence and reliability for holding the core subcritical under cold conditions
Solution Approach 1:
The invention divides the reactivity control function into two independent systems: control rods for power level control and a movable neutron reflector/moderator system for independent reactivity control and subcritical holding. This segmentation provides the required independence between control systems.
Solution Approach 2:
The patent introduces a movable neutron reflector/moderator as an intermediary component between the core and the external environment. This mediator provides an additional layer of control that is independent of the control rod system, enhancing reliability and independence.
2Adaptability or versatility
If water property manipulation is used for moderator control, then BWR and PWR can achieve reactivity control, but this method is not applicable to diverse reactor types
Solution Approach 1:
The movable neutron reflector/moderator system serves multiple functions: it acts as a reflector, a moderator, and a control mechanism. This multi-functionality makes the system universally applicable to various reactor types without requiring water property manipulation, simplifying the control approach across different reactor designs.
Solution Approach 2:
The invention changes the physical parameter being controlled from water properties (chemical composition, phase) to the physical position and geometry of the neutron reflector/moderator blocks. This parameter change enables applicability to all reactor types regardless of their cooling/moderation medium.
3Productivity
If control rods are used for reactivity control, then power changes can be managed, but the risk of accidents like rod withdrawal remains
Solution Approach 1:
The movable neutron reflector/moderator system is positioned to surround the core, providing a safety cushion that can rapidly respond to prevent criticality accidents. This pre-positioned protective barrier reduces the risk of accidents like rod withdrawal by providing an independent control mechanism.
Solution Approach 2:
The system incorporates neutron detection systems that provide real-time feedback on core conditions. This feedback enables the movable reflector/moderator to respond dynamically to changing conditions, preventing accidents by maintaining safe operating parameters.
4Reliability
If separate reactivity control systems are provided, then NRC design criteria are met, but the device complexity increases
Solution Approach 1:
The patent combines the neutron reflector and moderator functions into a single movable system, reducing the number of separate components. This merging maintains the required independence from control rods while simplifying the overall system structure compared to having entirely separate control mechanisms.
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 solution enhances reactor safety by enabling independent control of reactivity changes, reducing the risk of accidents like rod withdrawal, and allowing for longer reactor operation cycles, thereby increasing safety and operational efficiency.
Implementation Method 1
movable neutron reflector/moderator blocks, which can be positioned to adjust neutron coupling and reflection
Implementation Method 2
movable neutron reflector/moderator blocks, which can be positioned to adjust neutron coupling and reflection
Data Source
AI summary
A block-type movable reflector/moderator (RM) for nuclear reactor control is disclosed. This reactor control system can be applied to all types of reactors regardless of design. This design for reactor control is used in addition to the necessary rod control system in accordance with the 10CFR50 design criteria. This allows for the requirements of the NRC to be met along with the ability for dual control on power control of any type reactor regardless of process output from the secondary plants.