Nuclear Reactor Cooling via Steam Discharge to IRWST
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Solution Overview
Problem
Conventional nuclear reactors rely on large-scale seawater cooling facilities for long-term cooling operations, which are costly, site-restricted, and vulnerable to pump failures, potentially leading to accidents like fuel meltdowns or hydrogen explosions.
Innovation Solution
A nuclear reactor long-term cooling system that includes a lower containment area, an In-Containment Refueling Water Storage Tank (IRWST), and a discharge pipe to direct steam into refueling water, allowing for passive cooling without seawater facilities, using internal pressure differences to manage steam discharge and prevent backflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large-scale seawater cooling facilities are used for long-term cooling operations, then cooling capability is improved, but construction cost increases and site restrictions are imposed
Solution Approach 1:
The invention extracts the essential cooling function from the complex seawater cooling system by using the existing IRWST and containment structure. The discharge pipe connects the containment to the IRWST, allowing steam to be condensed by refueling water without requiring external seawater cooling facilities, thus eliminating the need for complex large-scale cooling infrastructure.
Solution Approach 2:
The IRWST, originally designed for refueling operations, is given a dual function by also serving as a cooling reservoir. The containment structure, designed to hold steam, is also used to direct steam to the IRWST for condensation. This multi-functionality eliminates the need for separate cooling facilities, reducing construction costs and device complexity.
2Reliability
If large-scale seawater cooling facilities are used for long-term cooling operations, then cooling capability is improved, but site restrictions are imposed
Solution Approach 1:
The invention extracts the cooling function from external seawater facilities and relocates it within the plant using the IRWST and containment structure. This internalization of the cooling function eliminates the requirement for proximity to seawater, thereby expanding site selection flexibility while maintaining cooling capability.
Solution Approach 2:
By making the IRWST and containment structure serve dual purposes (refueling and cooling), the invention creates a self-sufficient cooling system that does not depend on external seawater resources. This universality enables the plant to be sited anywhere, significantly improving adaptability to different locations.
3Ease of operation
If seawater cooling facilities with pumps are used, then cooling operation is enabled, but system reliability deteriorates due to pump failure risk
Solution Approach 1:
The invention employs passive cooling where steam naturally flows from the containment to the IRWST through the discharge pipe driven by pressure differential and gravity. This self-service mechanism eliminates the need for active pump operation, removing the reliability risk associated with pump failures while maintaining continuous cooling capability.
Solution Approach 2:
The invention replaces the mechanical pump-based active cooling system with a passive cooling system utilizing natural pressure differential and gravity-driven flow. This substitution eliminates mechanical components prone to failure, thereby improving system reliability while maintaining cooling operation.
4Device complexity
If passive cooling without seawater facilities is used, then construction cost is reduced and site flexibility is improved, but cooling effectiveness may be compromised
Solution Approach 1:
The invention ensures cooling effectiveness by utilizing the large volume of refueling water in the IRWST as the cooling medium. The containment structure is designed to efficiently direct steam to the water, maximizing heat transfer. This approach maintains adequate cooling effectiveness while eliminating complex seawater facilities, achieving both cost reduction and reliable cooling.
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
Enables safe, long-term cooling operations without seawater facilities, reducing construction costs and site restrictions, and ensuring continuous cooling even without seawater, thereby enhancing nuclear plant safety and reliability.
Implementation Method 1
a discharge pipe configured to connect the lower containment area to the IRWST, and to discharge steam of the lower containment area to the refueling water when an accident occurs
Implementation Method 2
having refueling water stored therein... discharge steam of the lower containment area to the refueling water
Implementation Method 3
discharge steam of the lower containment area to the refueling water... steam containing radioactive substances generated from the reactor coolant system
Data Source
AI summary
A nuclear reactor cooling system comprises a containment area, an In-Containment Refueling Water Storage Tank (IRWST), and a discharge pipe. The containment area is formed to enclose a reactor coolant system. The IRWST is disposed outside the containment area. The discharge pipe discharges steam from the containment area to refueling water in the IRWST when an accident occurs. A steam intake pipe has one end in fluid connection with an upper space of the IRWST, and another end in fluid connection with a radioactive substance reduction tank which stores cooling water. The steam intake pipe allows steam to flow from the upper space of the IRWST into the cooling water in the reduction tank.