Nuclear Fuel Element Cleaning Apparatus with Intermittent Flow
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Solution Overview
Problem
Nuclear fuel elements in BWR reactors face issues with metal particles and deposits accumulating inside, causing abrasion damage and reduced heat exchange, which conventional filters cannot capture due to their small size and adherence to internal surfaces.
Innovation Solution
An apparatus with a flow channel and filter element is connected to the fuel element to create a liquid flow, using a pump and adjustable flow valve to detach and capture particles and deposits, with an intermittent flow mechanism to effectively remove them without dislodging the apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional filters are used in the reactor water system, then particles circulating with reactor water can be captured, but small particles trapped inside fuel elements cannot be removed
Solution Approach 1:
The fuel element cleaning process is segmented into distinct phases: a first cleaning phase with lower flow rate for initial particle removal, and a second cleaning phase with higher flow rate for detached particle removal. This segmentation allows the system to address different particle states (adhered vs. detached) with appropriate flow conditions, overcoming the limitation of conventional single-phase filtering
Solution Approach 2:
The cleaning system employs periodic action by alternating between the first cleaning phase with lower flow rate and the second cleaning phase with higher flow rate. This periodic variation in flow rate creates dynamic cleaning conditions that effectively remove both adhered and detached particles, enhancing the overall particle capture capability beyond what continuous single-mode filtration can achieve
2Productivity
If high liquid flow is used to detach particles from fuel element surfaces, then particle removal is improved, but risk of dislodging the cleaning apparatus increases
Solution Approach 1:
The system dynamically adjusts the liquid flow rate through the fuel element by transitioning between a first lower flow rate during the initial cleaning phase and a second higher flow rate during the second cleaning phase. This dynamic flow rate adjustment optimizes particle detachment efficiency while managing apparatus stability, as the higher flow rate is applied only after the apparatus is securely positioned and initial particles are removed
Solution Approach 2:
The cleaning process uses periodic action by alternating between low flow rate periods (first cleaning phase) and high flow rate periods (second cleaning phase). This periodic variation allows the system to achieve high particle detachment efficiency during high flow periods while maintaining apparatus stability during low flow periods, effectively resolving the contradiction between productivity and reliability
3Manufacturing precision
If fuel elements are removed from the reactor tank for cleaning, then thorough cleaning is possible, but operational time is lost and contamination risk increases
Solution Approach 1:
The cleaning system enables self-service cleaning of fuel elements by directly attaching the cleaning apparatus to the fuel element and using reactor water itself as the cleaning medium. The pump draws reactor water through the fuel element, creating liquid flow that detaches particles from internal surfaces. This eliminates the need to remove fuel elements from the reactor tank, maintaining operational continuity while achieving thorough cleaning
Solution Approach 2:
The cleaning apparatus is designed with multi-functionality to perform both cleaning and particle capture functions within the reactor tank environment. The system can clean multiple fuel elements sequentially and captures detached particles in a collection container, providing a universal solution that maintains reactor operational time while achieving thorough cleaning of fuel element internal surfaces
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 apparatus efficiently detaches and captures particles and deposits from the fuel element's internal surfaces, improving heat exchange and preventing abrasion damage by utilizing a liquid flow and filter element, allowing for effective cleaning without requiring fuel element removal.
Implementation Method 1
a flow means that is adapted to create, at least during a part of a cleaning process of the fuel element, a liquid flow through the inner space of the fuel element
Implementation Method 2
a filter element positioned in the flow channel, the filter element being adapted to capture particles and deposits that are transported with the liquid flow from the inner space of the fuel element
Implementation Method 3
When the liquid means of the apparatus is activated a liquid flow is created through the fuel element. By creating a liquid flow that may be greater or less than the liquid flow through the fuel element during operation, such particles can be detached and transported with the liquid flow out of the fuel element via the opening
Data Source
AI summary
The present invention relates to an apparatus and a method for cleaning a nuclear fuel element in a liquid filled space. The fuel element comprises an inner space with an opening. The apparatus comprises a connecting element, which is adapted to be connected to a portion of the fuel element, which comprises said opening and flow means, which is adapted to create, at least during a part of a cleaning process of the fuel element, a liquid flow through inner space of the fuel element via said opening.