Water Injection Device Using Gravity Decoupled From Alloy
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Solution Overview
Problem
Existing water injection devices for reactor containment vessels face reliability issues due to the use of low melting point alloys for holding members, which affect the closing force and stability during temperature rises, especially in emergency situations where external power is not available.
Innovation Solution
A water injection device with a disk and swing arm mechanism, where a weight connected via a swing lever is supported by a low melting point alloy, allowing for reliable closure and opening of the flow path without relying on the mechanical characteristics of the alloy, and featuring a seal weld for enhanced sealing and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a holding member made of low melting point alloy is used to fix the disk, then the device can automatically open at elevated temperatures, but the reliability of the closing mechanism deteriorates due to dependence on the mechanical characteristics of the alloy
Solution Approach 1:
The device separates the temperature sensing function (low melting point alloy) from the closing force generation function (weight). The alloy segment melts at elevated temperatures to release the constraint, while the weight segment provides reliable gravitational closing force independent of alloy mechanical properties.
Solution Approach 2:
The swing arm acts as an intermediary mechanism that translates the release of the low melting point alloy into disk opening motion. Meanwhile, the weight connected via swing lever serves as an intermediary that provides stable closing force through gravity, decoupling the reliability of the closing mechanism from the mechanical characteristics of the alloy.
2Reliability
If the holding member is cooled by water from the pressure suppression pool, then the disk remains closed during normal operation, but the operation stability deteriorates during temperature rise
Solution Approach 1:
The weight connected via swing lever provides a gravitational counterbalance that ensures stable disk closing during normal operation. This gravitational force is independent of water cooling effects, maintaining operational stability even during temperature rises when cooling efficiency may deteriorate.
3Productivity
If the disk is pushed up by water head to open the flow path, then water injection can be achieved, but the closing force depends on the mechanical characteristics of the low melting point alloy
Solution Approach 1:
The device replaces dependence on the mechanical strength of the low melting point alloy with gravitational force from the weight. The closing force is now determined by the weight's gravitational pull transmitted through the swing lever, rather than the mechanical properties of the temperature-sensitive alloy.
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 device ensures reliable shut-off of cooling water during normal operations and quick water injection during emergencies without external power, improving reliability and stability by decoupling the closing mechanism from the low melting point alloy's mechanical characteristics and enhancing sealing performance.
Implementation Method 1
a temperature-actuated valve mechanism which is closed during a normal operation of a nuclear power plant and is automatically opened when the temperature of a lower portion of the reactor containment vessel is higher than a predetermined temperature
Implementation Method 2
A water injection device with a disk and swing arm mechanism, where a weight connected via a swing lever is supported by a low melting point alloy
Data Source
AI summary
A high reliable water injection device is provided that injects water into a reactor containment vessel and can reliably shut off cooling water at normal times and quickly and reliably inject water into the reactor containment vessel without the need for external power, in a case of emergency. The water injection device injects water into a reactor containment vessel includes a flow path through which cooling water is supplied; a disk that closes the flow path; a swing arm that is connected to the disk and performs closing and opening of the flow path by the disk; and a weight that is connected to the swing arm via a swing lever, in which the weight is supported by a support member made of a low melting point alloy.