Multi-Stage Safety Injection Device for Passive Reactor Cooling
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Solution Overview
Problem
Current safety injection systems for reactors are complex and require multiple facilities to manage varying coolant flow rates during accidents, leading to inefficiencies and potential delays in pressure balancing and flow rate switching.
Innovation Solution
A multi-stage safety injection device with a safety injection tank, pressure balance line, safety injection line, and flow control line, featuring multiple safety injection ports and orifices to adjust flow rates based on water level reduction, allowing for step-wise coolant injection and pressure balancing without external energy sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple safety injection facilities are used to manage varying coolant flow rates, then the required safety injection characteristics can be satisfied, but the facility complexity increases and potential delays in pressure balancing and flow rate switching occur
Solution Approach 1:
The single safety injection tank is segmented into multiple injection zones with different flow rates by creating multiple safety injection ports at different heights. Each port serves as an independent injection channel, allowing the system to provide multiple flow rate stages (high, medium, low) simultaneously or sequentially based on accident conditions, thereby satisfying various safety injection characteristics without requiring multiple separate tanks
Solution Approach 2:
The safety injection tank is designed to perform multiple functions by providing different coolant injection flow rates through different ports. The same tank structure serves as a high-flow rate injection source when upper ports are active, a medium-flow rate source when middle ports are active, and a low-flow rate source when lower ports are active, eliminating the need for separate dedicated tanks for each function
2Device complexity
If a single type of safety tank is used, then facility complexity is reduced, but various safety injection characteristics cannot be satisfied
Solution Approach 1:
The injection function is segmented vertically within the single tank by positioning multiple safety injection ports at different heights. This spatial segmentation allows different portions of the same tank to serve different injection rate functions, enabling the system to meet various safety injection characteristics (high flow rate for initial accidents, medium flow rate for early stages, low flow rate for late stages) using one unified tank structure
Solution Approach 2:
The system dynamically adapts its injection characteristics by selectively activating different safety injection ports based on the accident scenario and required flow rate. The controller can switch between ports to provide high, medium, or low flow rates as needed, making the single tank structure dynamically versatile rather than static
3Speed
If high flow rate of coolant is injected at the initial stage of accident, then the core level can be quickly restored, but the pressure and water level within the reactor vessel decrease rapidly
Solution Approach 1:
The safety injection system operates in periodic stages rather than continuously at constant high flow rate. The controller activates upper injection ports for high flow rate injection during initial accidents, then transitions to medium flow rate ports, and finally to low flow rate ports as the accident evolves. This periodic switching of injection rates allows rapid initial response while preventing excessive and unsustainable pressure drops
Solution Approach 2:
The injection system dynamically adjusts flow rates based on real-time accident conditions and reactor vessel state. By switching between different injection ports with different flow characteristics, the system can provide high flow rate when needed for rapid core level restoration, then transition to lower flow rates to stabilize pressure and water level, optimizing both speed and stability
4Productivity
If medium flow rate of coolant is injected at early and middle stages of accident, then coolant discharge flow rate can be balanced, but the injection duration is extended
Solution Approach 1:
The system implements periodic switching between different injection ports to provide medium flow rate injection during early and middle accident stages. This controlled periodic injection maintains coolant discharge flow rate balance while extending the effective injection duration to address prolonged cooling needs, rather than relying on continuous high flow rate that would deplete the tank too rapidly
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
Simplifies safety injection facilities by varying coolant flow rates according to required characteristics, ensuring continuous and reliable coolant injection for extended periods without operator intervention or active power, enhancing reactor safety and reducing facility complexity.
Implementation Method 1
a safety injection tank formed to contain coolant to be injected into a reactor vessel by a gravitational head of water when an accident occurs
Implementation Method 2
a pressure balance line connected to the reactor vessel and safety injection tank to form a pressure balance state between the reactor vessel and the safety injection tank
Implementation Method 3
a flow control line extended from the safety injection line to an inner portion of the safety injection tank, and provided with safety injection ports into which coolant is injected at predetermined heights, respectively, to reduce the flow rate of coolant injected into the reactor vessel step by step
Data Source
AI summary
The present disclosure may disclose a multi stage safety injection device and a passive safety injection system having the same, including a safety injection tank formed to contain coolant to be injected into a reactor vessel by a gravitational head of water when an accident occurs in which the pressure or water level of the reactor vessel is decreased, a pressure balance line connected to the reactor vessel and safety injection tank to form a pressure balance state between the reactor vessel and the safety injection tank, a safety injection line connected to a lower end portion of the safety injection tank and the reactor vessel to inject coolant to the reactor vessel in a pressure balance state between the reactor vessel and the safety injection tank, and a flow control line extended from the safety injection line to an inner portion of the safety injection tank, and provided with safety injection ports into which coolant is injected at predetermined heights, respectively, to reduce the flow rate of coolant injected into the reactor vessel step by step according to the water level reduction of the safety injection tank, in order to inject coolant to the reactor vessel at multi stages.