Reactor Vessel Cooling via Secondary Circuit Breach
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Solution Overview
Problem
Current solutions for managing corium in pressurized water nuclear reactors during accidents face challenges such as requiring large infrastructure, breaking the containment barrier, and not adequately addressing the risk of vessel piercing due to the focusing effect, which can lead to uncontrolled dispersal of highly radioactive and thermally potent corium.
Innovation Solution
A method involving the secondary circuit's water, at higher pressure, being intentionally broken into the primary circuit to flow over the corium bath's liquid metallic layer, providing passive cooling by injecting water at a controlled rate through a calibrated breach, thereby reducing the thermal power transmission to the vessel walls and preventing piercing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If water from the secondary circuit is broken into the primary circuit to cool the corium bath, then the thermal power transmission to vessel walls is reduced and piercing risk is eliminated, but the containment barrier between primary and secondary circuits is broken
Solution Approach 1:
The patent applies preliminary anti-action by intentionally breaking the containment barrier between primary and secondary circuits before the focusing effect can cause vessel piercing. The controlled breach allows secondary circuit water to flow into the primary circuit and cool the corium bath's liquid metallic layer, preventing the harmful thermal transmission to vessel walls. This proactive measure eliminates the piercing risk while accepting the controlled breach of the containment barrier.
2Ease of manufacture
If a calibrated breach is created to allow controlled water flow from secondary to primary circuit, then passive cooling is achieved without additional infrastructure, but the fluidic insulation between circuits is compromised
Solution Approach 1:
The patent applies the taking out principle by extracting the fluidic insulation barrier between primary and secondary circuits through a calibrated breach. This allows the secondary circuit water to be taken out and flow into the primary circuit, providing passive cooling capability without requiring additional cooling infrastructure. The breach is deliberately created to remove the insulation barrier that would otherwise prevent this cooling action.
3Device complexity
If the secondary circuit water is used to cool the corium bath, then existing infrastructure is utilized without additional components, but the pressure differential between circuits must be overcome
Solution Approach 1:
The patent applies the blessing in disguise principle by converting the pressure differential between circuits, which normally prevents mixing, into a beneficial force. The higher pressure in the secondary circuit is utilized to drive water through the calibrated breach into the lower-pressure primary circuit, providing the necessary flow for cooling without requiring additional pumps or mechanical drive systems. The pressure difference becomes the driving force for the cooling action.
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
This approach effectively reduces and eliminates the risk of vessel piercing by the focusing effect, as the cooling duration and flow rate manage the thermal power transmission, allowing for safe containment of corium within the vessel without additional infrastructure or components.
Implementation Method 1
providing passive cooling by injecting water at a controlled rate through a calibrated breach, thereby reducing the thermal power transmission to the vessel walls
Implementation Method 2
the secondary circuit's water, at higher pressure, being intentionally broken into the primary circuit to flow over the corium bath's liquid metallic layer
Data Source
AI summary
A safety method for a reactor including a primary circuit and a secondary circuit fluidly isolated from the primary circuit, and a steam generator, and in the event of a meltdown of the core of the reactor with the formation of a corium bath in a bottom of the vessel and the formation of a liquid metallic layer at the surface of the corium bath, the method includes: a break-up by explosion of the fluidic insulation to set the secondary circuit in fluidic communication with the primary circuit so that the secondary fluid follows the primary circuit to flow inside the vessel over the liquid metallic layer of the corium bath.