Passive Containment Cooling System for Nuclear Power Plants
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Solution Overview
Problem
Conventional passive containment cooling systems fail to safely cool the containment vessel during transients like station blackouts, leading to potential overpressure and radioactive material release, as they rely on external power sources and cannot function when filtered venting systems are activated.
Innovation Solution
A nuclear power plant design incorporating a reactor pressure vessel, dry well, wet well with a suppression pool, and a heat exchanger system where gas from the dry well is directed to a heat exchanger submerged in a cooling water pool, allowing non-condensable gases to be vented externally without relying on the wet well, enabling passive cooling without external power and avoiding external water injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional passive containment cooling system is used, then the system can cool the containment vessel during normal operations, but it fails to function during transients like station blackouts when filtered venting systems are activated
Solution Approach 1:
The invention divides the gas flow path into separate segments: one path through the wet well and suppression pool, and another direct path from the dry well to the heat exchanger. This segmentation allows the system to handle different operating conditions independently, maintaining reliability during transients when the wet well path may be compromised.
Solution Approach 2:
The invention introduces a direct gas supply line as an intermediary pathway that bypasses the wet well and suppression pool. This mediator allows gas to reach the heat exchanger directly during transients, ensuring the cooling function remains operational when conventional paths fail.
2Reliability
If the gas vent pipe is connected to the wet well, then the system follows conventional design, but it cannot vent non-condensable gases effectively when filtered venting is activated
Solution Approach 1:
The gas venting system is segmented into two independent pathways: the conventional wet well path and a new direct path from the dry well to the heat exchanger. This segmentation allows each path to serve specific functions, ensuring reliable gas venting under various conditions without excessive complexity.
Solution Approach 2:
The direct gas supply line serves multiple functions: it provides a backup cooling path during transients, enables direct non-condensable gas venting, and maintains system operation when the wet well path is unavailable. This multi-functionality improves reliability without proportionally increasing complexity.
3Power
If external power sources are used for cooling systems, then active cooling can be provided during normal operations, but the system cannot function during station blackouts
Solution Approach 1:
The passive heat exchanger system operates autonomously using natural convection and temperature differences between the gas and cooling water. This self-service mechanism eliminates dependence on external power sources, ensuring cooling functionality remains available during station blackouts and other emergency conditions.
Solution Approach 2:
The invention replaces active mechanical cooling systems (pumps, fans powered by electricity) with a passive thermal convection system. This substitution eliminates the need for external power while maintaining effective cooling capability, directly resolving the contradiction between power availability and system reliability during blackouts.
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 system effectively cools the containment vessel during station blackouts, preventing overpressure and radioactive material release, maintaining reactor safety and integrity, and allowing for immediate restart of power generation without contaminating the environment.
Implementation Method 1
a heat exchanger (16) which includes an inlet plenum (17), an outlet plenum (18) and a plurality of heat exchanger tubes (19), and is at least partially submerged in cooling water (14)
Implementation Method 2
steam in the reactor pressure vessel 2 to be released into the suppression pool 6
Implementation Method 3
a cooling water pool (13) which is placed outside the containment vessel (3) and stores cooling water (14)
Implementation Method 4
The vacuum breakers 9 are activated and opened when the pressure inside the wet well 5 is higher than the pressure inside the dry well 4, and the differential pressure exceeds a set pressure
Data Source
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AI summary
According to an embodiment, a nuclear power plant has a core (1); a reactor pressure vessel (2); a dry well (4); a wet well (5); a vacuum breaker (9); a containment vessel (3) including the dry well (4), the LOCA vent pipe (8), the wet well (5), and the vacuum breaker (9); a cooling water pool (13) placed outside the containment vessel; a heat exchanger (16) at least partially submerged in cooling water (14); a gas supply pipe (20) connected to the inlet plenum (17) of the heat exchanger (16) and the dry well (4); a condensate return pipe (21) connected to the outlet plenum (18) of the heat exchanger (18) and the containment vessel (3); and a gas vent pipe (22) connected to the outlet plenum (18) of the heat exchanger (16) and an outside of the wet well (5) so that non-condensable gas inside the heat exchanger (16) is released out of the wet well (5). The gas vent pipe (22) is not connected to the wet well (5).