Uranium Gadolinium Oxygen Burnable Poison for Reactivity Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current nuclear fuel technologies face challenges in controlling reactivity in light water reactors, particularly due to the limitations and risks associated with using boron as a neutron poison, including corrosion, tritium production, and reactivity accidents, while also requiring increased fuel enrichment to extend reactor operation cycles.
Innovation Solution
A novel material based on uranium, gadolinium, and oxygen with a crystalline phase enriched in gadolinium, exhibiting a cubic crystallographic structure, is developed, which serves as a burnable neutron poison compatible with sintering conditions of fuel pellets, allowing for controlled reactivity and reduced boron usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If boron is used as neutron poison to control reactivity, then reactivity control is improved, but corrosion and tritium production increase
Solution Approach 1:
The patent changes the chemical composition parameter by replacing boron with gadolinium oxide as the neutron poison. This substitution eliminates the harmful effects of boron (corrosion, tritium production) while maintaining the essential function of reactivity control through neutron absorption by gadolinium isotopes
Solution Approach 2:
The patent uses burnable poison (gadolinium oxide) that is consumed during reactor operation, replacing the need for soluble boron that requires continuous management. The burnable poison gradually disappears as it absorbs neutrons, providing automatic reactivity management without the ongoing harmful effects associated with boron
2Productivity
If fuel enrichment is increased to extend reactor operation cycles, then productivity is improved, but the need for negative reactivity increases
Solution Approach 1:
The patent incorporates burnable poison (gadolinium oxide) into the fuel pellets before reactor operation. This preliminary action provides the necessary negative reactivity at the start of the cycle, allowing higher fuel enrichment and longer operation cycles without increasing the need for additional negative reactivity sources during operation
3Stability of the object's composition
If homogeneous distribution of boron is used, then power distribution is improved, but the amount of boron required increases
Solution Approach 1:
The patent employs heterogeneous distribution of gadolinium oxide within the fuel pellets, creating local regions of different neutron absorption. This local quality variation allows for effective reactivity control with reduced overall boron equivalent content, while still maintaining acceptable power distribution through the heterogeneous poison distribution pattern
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 material effectively controls reactor reactivity, reduces boron usage, and minimizes corrosion and tritium production risks, enabling longer reactor operation cycles with improved thermal conductivity and safety.
Implementation Method 1
Among them, the most absorbent are 155Gd and 157Gd, these two isotopes representing nearly 100% of the absorption related to natural gadolinium. Subsequent to the neutron capture, the 155 and 157 isotopes of gadolinium are transmuted into 156 and 158 isotopes respectively
Implementation Method 2
The material according to the invention is produced under the same sintering conditions as the uranium oxide; it is cosinterable with UO2
Data Source
AI summary
The present invention relates to a novel material made of uranium, gadolinium and oxygen, having a crystalline phase having cubic crystallographic structure, having an atomic ratio Gd/[Gd+U] of 0.6 to 0.93, the uranium being present in an oxidation state of +IV and/or +V. The invention further relates to the use of such a material as a consumable neutron poison of a fuel element.