Thermal-Neutron Reactor Core with Burnable Poison for Negative Temperature Coefficient
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Small, lightweight nuclear reactor systems using metal hydride as a moderator often exhibit a positive temperature reactivity coefficient, which compromises safety, and the addition of gadolinium as a burnable poison exacerbates this issue, requiring additional control measures.
Innovation Solution
A thermal-neutron reactor core design incorporating a solid moderator, fissile fuel, and a cooling system, along with multiple burnable poisons like cadmium and europium, which are strategically selected and proportioned to ensure a negative temperature reactivity coefficient across normal to high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If metal hydride is used as a moderator to achieve small size and lightweight reactor system, then the reactor size and weight are reduced, but the temperature reactivity coefficient becomes positive which compromises safety
Solution Approach 1:
The invention changes the physical-chemical parameters of the moderator by using a solid moderator with controlled density and neutron scattering properties. By adjusting the moderator's density and composition, the patent achieves a negative temperature reactivity coefficient while maintaining the compact reactor design, thus resolving the contradiction between lightweight design and safety.
2Quantity of substance
If gadolinium is added as burnable poison to suppress excess reactivity, then excess reactivity is controlled, but the temperature reactivity coefficient becomes far more positive
Solution Approach 1:
The invention introduces a specific solid moderator as an intermediary material that mediates between the burnable poison and the neutron spectrum. This moderator compensates for the positive temperature coefficient effect introduced by gadolinium, allowing excess reactivity control while maintaining a negative temperature reactivity coefficient through the moderator's neutron scattering and thermalization properties.
3Reliability
If control rods are added to ensure safety when using gadolinium, then safety is improved, but the device complexity increases
Solution Approach 1:
The invention makes the reactor core self-regulating by designing the fuel and moderator composition to inherently provide a negative temperature reactivity coefficient. This eliminates the need for active control rods and complex control systems, as the reactor automatically responds to temperature changes, thus improving safety while reducing device complexity.
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 design effectively maintains a negative temperature reactivity coefficient, enhancing safety by ensuring the reactor's stability and operability without the need for additional control rods based on temperature.
Implementation Method 1
a solid moderator, the small reactor core having a negative temperature reactivity coefficient
Implementation Method 2
a plurality of kinds of burnable poison included in the fuel
Implementation Method 3
a cooling tube parallel to the lengthwise direction of the moderator
Implementation Method 4
cooling system
Data Source
AI summary
A thermal-neutron reactor core includes: a solid moderator expanding to a lengthwise direction; a fuel in the moderator, parallel to the lengthwise direction of the moderator, the fuel containing a fissile material; a cooling tube parallel to the lengthwise direction of the moderator; and a plurality of kinds of burnable poison included in the fuel. The may contain a metal hydride. Furthermore, the plurality of kinds of burnable poison may include one burnable poison containing a concentration of one particular isotope of that one burnable poison.