Isolation Valve Vessel Assembly for Type 1 LOCA Containment
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Solution Overview
Problem
Light water nuclear reactors face challenges in preventing Type 1 Loss of Coolant Accidents (LOCAs) due to leaks between the reactor vessel and valve rooms, which can lead to uncontrolled coolant discharge and reactor water storage tank drainage.
Innovation Solution
The implementation of an isolation valve assembly with a sealed volume capable of withstanding reactor pressure, featuring a spool piece and an isolation valve vessel with redundant valves to prevent fluid flow out of the pressure vessel, thereby isolating the reactor from potential coolant losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If isolation valves are placed in valve rooms with piping connections, then coolant flow control is enabled, but Type 1 LOCA risk increases due to potential leaks between vessel and valve room
Solution Approach 1:
The patent extracts the isolation valves from the external valve rooms and relocates them inside the pressure vessel. This eliminates the vulnerable piping connections between the vessel and valve rooms, thereby preventing Type 1 LOCAs while maintaining coolant flow control capability through the integrated valve assembly
Solution Approach 2:
The patent merges the isolation valves with the pressure vessel by providing penetrations directly through the vessel wall and mounting valves internally. This integration eliminates separate valve rooms and external piping, creating a unified system that maintains operational control while eliminating leak paths
2Adaptability or versatility
If multiple vessel penetrations are provided for coolant lines, then operational flexibility is improved, but LOCA risk increases due to more potential leak points
Solution Approach 1:
The patent combines multiple coolant line functions through integrated valve assemblies that are mounted directly on the pressure vessel. Each assembly handles both coolant flow and isolation functions, reducing the number of separate penetrations and connections needed while maintaining operational flexibility
Solution Approach 2:
The valve assemblies serve multiple functions simultaneously: they control coolant flow, provide isolation capability, and are integrated into the pressure vessel structure. This multi-functionality reduces the number of separate components and connections, thereby reducing LOCA risk while maintaining operational versatility
3Power
If external piping is used for steam generators, then heat transfer efficiency is maintained, but system complexity and LOCA risk increase
Solution Approach 1:
The patent extracts the isolation valve function from external piping systems and integrates it directly into the pressure vessel. This eliminates the need for complex external piping connections while maintaining the heat transfer functionality through the integrated assembly
Solution Approach 2:
The patent merges the steam generator connections with the pressure vessel by providing direct penetrations and integrated valve assemblies. This reduces the complexity of external piping systems while maintaining heat transfer efficiency through the unified structure
Data Source
AI summary
Apparatuses for reducing or eliminating Type 1 LOCAs in a nuclear reactor vessel. A nuclear reactor including a nuclear reactor core comprising a fissile material, a pressure vessel containing the nuclear reactor core immersed in primary coolant disposed in the pressure vessel, and an isolation valve assembly including, an isolation valve vessel having a single open end with a flange, a spool piece having a first flange secured to a wall of the pressure vessel and a second flange secured to the flange of the isolation valve vessel, a fluid flow line passing through the spool piece to conduct fluid flow into or out of the first flange wherein a portion of the fluid flow line is disposed in the isolation valve vessel, and at least one valve disposed in the isolation valve vessel and operatively connected with the fluid flow line.