Embedded Check Valve Nozzle for Nuclear LOCA Isolation
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Solution Overview
Problem
Conventional prevention devices for loss of coolant accidents (LOCA) in nuclear reactors face challenges such as increased manufacturing complexity due to large connection nozzles, difficulty in seismic design due to height restrictions, and maintenance complications, particularly in integral reactors where large check valves are not required.
Innovation Solution
A prevention device featuring a nozzle portion with a communication hole and a check valve mounting portion embedded inside, allowing for dual check valves that open and close based on pressure differences, with reinforced nozzle portions and finishing portions to prevent coolant outflow and facilitate maintenance without adjusting water levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dual isolation valves are installed in outflow and inflow pipes to separate both pipes, then loss of coolant accident is alleviated, but the size of connection nozzle portion increases and manufacturing difficulty increases
Solution Approach 1:
The invention divides the isolation function into two separate check valves: one installed in the outflow pipe and another in the inflow pipe. This segmentation allows each valve to be independently sized and manufactured, avoiding the need for a large connection nozzle portion that would be required if both valves were integrated into a single assembly. The segmented approach maintains safety functionality while reducing manufacturing complexity.
2Reliability
If check valves are installed in outflow and inflow pipes to enable automatic operation by pressure difference, then loss of coolant accident is alleviated, but the size of check valves increases and nozzle portion size increases
Solution Approach 1:
The invention applies different design approaches to different locations: in the outflow pipe where high pressure differential exists, a compact check valve design is used that leverages the existing pressure difference for operation. In the inflow pipe, a similarly compact design is applied. This localized optimization ensures automatic response capability while minimizing the volume of each check valve and the surrounding nozzle portion, avoiding the need for oversized components.
3Reliability
If large-sized check valve is installed on connection nozzle of loop type reactor, then loss of coolant accident is reduced, but installation becomes very difficult
Solution Approach 1:
The invention segments the check valve system into two smaller units distributed in the outflow and inflow pipes rather than installing one large check valve in a single location. This segmentation transforms a difficult installation task (installing one large valve) into two simpler tasks (installing two smaller valves), significantly improving ease of operation and installation while maintaining the same safety function.
4Ease of operation
If injection line is connected to middle of reactor vessel for gravity water head operation, then seismic design difficulty increases and cost increases, but injection operation is enabled
Solution Approach 1:
The check valves in the system operate automatically based on pressure differentials without requiring external control signals or complex positioning mechanisms. The outflow check valve automatically closes when backflow occurs, and the inflow check valve automatically opens when forward flow is needed. This self-service operation simplifies the overall system design, reduces seismic design complexity, and eliminates the need for complex control systems while maintaining reliable injection functionality.
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
The solution effectively blocks reactor coolant outflow during LOCA, enhances safety by reducing damage probability, allows for flexible injection line positioning, and simplifies maintenance by eliminating the need to adjust water levels, thereby improving the overall safety and cost-effectiveness of nuclear reactor design.
Implementation Method 1
dual check valves that open and close based on pressure differences
Data Source
AI summary
The present invention relates to a prevention device for loss of coolant accident (LOCA) and a nuclear reactor having the same. The prevention device for LOCA includes a nozzle portion integrally formed in a reactor vessel and having a communication hole communicating with the inside of the reactor vessel, a nozzle finishing portion assembled to the nozzle portion and an injection line for injecting a fluid to the inside of the reactor vessel respectively on both sides thereof in a communicating manner, and a check valve mounting portion installed to be embedded inside the nozzle portion and having at least one check valve opened by flow such that the fluid is injected into the reactor vessel, wherein the check valve blocks outflow of a reactor coolant from the reactor vessel in case of failure of the injection line.