Vented Nuclear Fission Fuel Module Gas Management
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Solution Overview
Problem
Nuclear fission reactors face challenges with fuel rod swelling, cracking, and rupture due to the accumulation of fission product solids and gases, which can lead to cladding corrosion, stress concentrations, and uncontrolled release of fission products into the coolant system, necessitating frequent reactor shutdowns and reduced design life.
Innovation Solution
A nuclear fission reactor system with vented nuclear fission fuel modules that include a valve body with a plenum for receiving gaseous fission products and a controllable valve for venting these products into the reactor vessel, utilizing a flexible diaphragm and removable cap to manage pressure and prevent backflow, thereby reducing stress on the cladding and minimizing the risk of cladding breach.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fission products are retained in fuel rods during normal operation, then fuel rod swelling and cladding stress increase, but frequent reactor shutdowns and reduced design life occur
Solution Approach 1:
The patent extracts harmful gaseous fission products from the fuel rod interior by providing vent passages that allow these gases to escape into the coolant flow, thereby reducing internal pressure and preventing fuel rod swelling and cladding stress while enabling continuous reactor operation
Solution Approach 2:
The patent introduces coolant as an intermediary medium that receives and transports gaseous fission products away from the fuel rod interior through the vent passages, preventing direct accumulation of gases that would cause swelling while maintaining reactor operation
2Stress or pressure
If fission product gases accumulate in fuel rods, then internal pressure increases causing cladding swelling and deformation, but controlled venting mechanisms are required
Solution Approach 1:
The patent implements a self-service venting mechanism where the coolant flow itself provides the driving force for gas removal through the vent passages, eliminating the need for external pumps or complex control systems while maintaining effective pressure management
Solution Approach 2:
The patent uses hydraulic principles by allowing coolant flow to carry gaseous fission products through the vent passages via buoyancy and flow-driven transport, providing simple passive pressure equalization without mechanical intervention
3Strength
If fuel pellets swell volumetrically, then they contact cladding causing stress concentrations, but heat transfer gaps are compromised
Solution Approach 1:
The patent removes gaseous fission products that cause fuel pellet swelling through vent passages, preventing the swelling that would lead to fuel-cladding contact and heat transfer gap closure, thereby maintaining both structural integrity and thermal efficiency
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 manages fission product gases, reducing the risk of fuel rod swelling and cladding damage, allowing for extended reactor operation and reduced frequency of shutdowns by controllably venting gases, thus maintaining reactor integrity and efficiency.
Implementation Method 1
A nuclear fission reactor system with vented nuclear fission fuel modules that include a valve body with a plenum for receiving gaseous fission products and a controllable valve for venting these products into the reactor vessel, utilizing a flexible diaphragm and removable cap to manage pressure and prevent backflow
Data Source
AI summary
Illustrative embodiments provide a nuclear fission reactor, a vented nuclear fission fuel module, methods therefor and a vented nuclear fission fuel module system.