Fluid Isolation Device for Nuclear Reactor Primary Circuit Filling
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Solution Overview
Problem
Current methods for filling the primary circuit of a nuclear reactor with water and removing air after shutdown are costly in terms of management time and can be harmful to the reactor's mechanical integrity, requiring numerous pressurizations and depressurizations, and are time-consuming, especially when preparing for reactor restarts.
Innovation Solution
A method involving a connection and fluid isolation device that allows water to be injected into the cooling loops at a controlled flow rate to fill the primary circuit without pressurization cycles, using existing safety injection circuits and minimizing pump usage, which reduces the time required for the process and extends the service life of the reactor components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dynamic venting method is used to fill the primary circuit with water, then the air is expelled from the steam generators, but numerous pressurizations and depressurizations are required which are harmful to the mechanical resistance of the vessel
Solution Approach 1:
The invention performs preliminary action by isolating the steam generator from the vessel before water filling begins. The connection device is positioned and sealed to create an isolated chamber, allowing water to be injected directly into the steam generator without requiring repeated pressurization cycles of the entire vessel. This preliminary isolation enables air to be expelled through the isolated connection device while avoiding mechanical stress on the vessel.
Solution Approach 2:
The invention segments the primary circuit by introducing a connection device that isolates the steam generator chamber from the main vessel. This segmentation creates a separate, controllable chamber where water can be injected and air expelled independently, eliminating the need for repeated pressurization and depressurization of the entire vessel system.
2Reliability
If dynamic venting method is used, then air is expelled from the steam generators, but the primary pump must be started and stopped multiple times which increases maintenance requirements
Solution Approach 1:
The connection device is preliminarily positioned and sealed to isolate the steam generator before water filling begins. This preliminary setup allows water to be injected directly into the isolated steam generator chamber, expelling air through the connection device without requiring the pump to start and stop multiple times, thereby reducing maintenance requirements.
3Reliability
If vacuum method is used to fill the primary circuit, then air is removed from the circuit, but the vacuum must be maintained during depressurization and filling phases which requires long preparation time
Solution Approach 1:
The connection device is preliminarily positioned and sealed to isolate the steam generator before water filling begins. This preliminary isolation eliminates the need to maintain vacuum during the filling process, as water can be injected directly into the isolated chamber. The process can be completed in approximately 12-14 hours without requiring extended vacuum maintenance, significantly reducing preparation time.
Solution Approach 2:
The invention extracts the steam generator from the main vessel system through the connection device, creating an isolated chamber. This extraction allows the filling process to occur independently without requiring vacuum maintenance of the entire primary circuit, thereby reducing the time required for preparation.
4Quantity of substance
If conventional filling methods are used, then the primary circuit is filled with water, but the process takes several days which reduces maintenance efficiency
Solution Approach 1:
The connection device is preliminarily positioned and sealed to isolate the steam generator before water filling begins. This preliminary isolation enables water to be injected directly into the steam generator chamber at controlled flow rates, filling the circuit completely in approximately 12-14 hours rather than several days, significantly improving maintenance efficiency.
Solution Approach 2:
The connection device acts as an intermediary element between the water injection system and the steam generator. It provides a controlled interface that allows water to be injected at regulated flow rates while isolating the steam generator from the vessel, enabling complete filling in 12-14 hours without requiring extended time.
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 method reduces the time needed for the process from several days to about 12-14 hours, decreases the mechanical stress on the reactor, and eliminates the need for frequent pump startups, thereby enhancing maintenance efficiency and compliance with safety regulations.
Implementation Method 1
injecting water into at least one cooling loop in the one of the first and second fluid circuits of said cooling loop to which the connection and fluid isolation device is connected, at a flow rate intended to fill said cooling loop with water while expelling the air from the steam generator
Implementation Method 2
placing in the vessel a connection and fluid isolation device adapted for connecting to one of said first and second fluid circuits of each cooling loop in order to substantially isolate said fluid circuit relative to the interior of the vessel
Data Source
AI summary
The method for filling water into and changing the air of a main circuit of a water-cooled nuclear reactor includes a step of placing a connection and fluid isolation device which is connected to a hot leg of each cooling loop of the main circuit so as to substantially insulate, from inside the vessel, the assembly of hot legs. The method also includes a step of injecting water through an injection circuit on at least one hot leg until each cooling loop is filled with water having changed the air from a steam generator and until the water level in the vessel reaches above the side openings of the vessel that correspond to the loops, after which the connecting device is taken out of the vessel. The connecting device is capable of using telescopic connection elements.