Nuclear Facility Control System Emergency Switching Logic
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Solution Overview
Problem
Conventional remote shutdown systems for nuclear facilities rely on analog circuit switches, requiring multiple coaxial cables and additional control circuits, which can lead to operator burden and incorrect switching operations due to potential failures like short circuits.
Innovation Solution
A control system with a first operation control device in a non-evacuation area and a second operation control device in an evacuation area, connected via a signal switching unit, AND circuit, and selector switches that ensure correct switching operations by requiring simultaneous emergency switch signals from both sides before switching, reducing the risk of incorrect operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a mode selection switch with contact points is used for switching between control panels, then switching operation can be performed, but additional control circuits and coaxial cables are required, increasing system complexity
Solution Approach 1:
The patent replaces the mechanical mode selection switch with contact points with a digital switching system using semiconductor-based signal switching units. This substitution eliminates the need for physical contact points and associated coaxial cables, reducing system complexity while maintaining switching functionality between the central control room control panel and remote shutdown panel.
Solution Approach 2:
The patent extracts and removes the mode selection switch from the system configuration. By eliminating this component entirely and using digital signal routing instead, the system avoids the complexity of additional control circuits and coaxial cables that would be required to support the mechanical switch.
2Productivity
If analog equipment is used for collective switching operations, then switching can be performed, but the operation differs from the central control room control panel, imposing burden on operators
Solution Approach 1:
The patent implements a universal digital control interface that can operate in multiple modes (normal operation and emergency shutdown) through a single standardized system. The signal switching unit and selector switches provide consistent digital operation across different functions, allowing operators to perform collective switching operations using the same digital interface rather than learning different analog equipment operations.
Solution Approach 2:
The patent changes the operational parameters from analog to digital domain. This parameter change enables consistent operation characteristics across different control functions, as digital signals provide uniform logic levels and switching behavior that simplifies operator interaction compared to varied analog equipment characteristics.
3Adaptability or versatility
If a mode selection switch is used, then switching between control panels is possible, but incorrect operation or short circuit may cause unintentional switching
Solution Approach 1:
The patent replaces the mechanical mode selection switch with a digital switching system that uses logic circuits and signal switching units. This substitution improves reliability by eliminating contact points that can fail or short circuit, and by using digital logic that provides more reliable switching control through defined logic states and error detection capabilities.
Solution Approach 2:
The patent introduces signal switching units and logic circuits as intermediaries between the control panels and the switching control signals. These intermediary components provide isolation and controlled signal routing, preventing direct contact between control lines and reducing the risk of short circuits causing unintentional switching.
Data Source
AI summary
A control system allows controlling a nuclear facility in an evacuation area. The control system includes a control device in ordinary use disposed in a non-evacuation area, an emergency control device—for emergency in the evacuation area, a plant control facility connectable to the control device—and the emergency control device, a signal switching unit that switches from a normal coupling to an emergency coupling based on an emergency switch signal, a first selector switch in the non-evacuation area, a second selector switch-in the evacuation area, an AND circuit configured to output the emergency switch signal to the signal switching unit in the case where the emergency switch signal is input from the first selector switch and the emergency switch signal is input from the second selector switch.