Nuclear Fuel Bundle Homogeneous Neutron Absorber Mixture
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Solution Overview
Problem
Nuclear reactors face challenges in maintaining even power generation throughout a cycle due to localized power spikes when fresh fuel bundles are inserted, as existing neutron absorbers can undesirably lower reactivity and limit fuel discharge burnup.
Innovation Solution
A nuclear fuel bundle design incorporating a homogeneous mixture of fissile materials like U-233, U-235, and Pu isotopes with neutron absorbers such as Gd, Dy, Hf, Er, and Eu, strategically distributed within the fuel elements to control reactivity and extend burnup while minimizing power impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If neutron absorbers are included in fuel bundles to reduce power spikes, then power generation stability is improved, but reactivity is lowered and fuel discharge burnup is limited
Solution Approach 1:
The patent applies local quality by distributing different neutron absorber materials (gadolinium, dysprosium, hafnium, erbium, europium) at specific locations within the fuel bundle - in inner elements, outer elements, and as ring structures. This spatial distribution allows different regions to have tailored neutron absorption characteristics, reducing power spikes locally while preserving overall reactivity and extending fuel burnup.
Solution Approach 2:
The patent uses composite materials by combining multiple neutron absorber materials with fissile materials in specific ratios and configurations. This composite approach creates a synergistic effect where the combination of absorbers provides better power flattening and reactivity control than single absorber materials, thereby extending fuel discharge burnup while maintaining power generation stability.
2Power
If fresh fuel bundles are inserted to maintain power generation, then power output is maintained, but localized power spikes occur
Solution Approach 1:
The patent applies preliminary action by pre-loading neutron absorbers into the fuel bundles before they are inserted into the reactor. These absorbers are strategically positioned to counteract the power spikes that will occur when fresh fuel is inserted, thereby maintaining power output while ensuring power distribution uniformity from the start of the fuel cycle.
Solution Approach 2:
The patent uses parameter changes by adjusting the concentration and distribution of neutron absorber materials within the fuel bundles. By optimizing the amount and placement of absorbers like gadolinium and dysprosium, the fuel bundle design modifies the neutron flux distribution parameters to reduce localized power spikes while maintaining overall power generation levels.
3Stability of the object's composition
If reactivity is lowered to reduce power spikes, then power generation stability is improved, but fuel discharge burnup is reduced
Solution Approach 1:
The patent applies dynamics by using burnable poison materials that dynamically change their absorption characteristics over time. The neutron absorbers are consumed during fuel burnup, gradually reducing their absorption effect as the fuel cycle progresses. This dynamic behavior allows for good reactivity control early in the cycle while maintaining adequate fuel discharge burnup, as the absorbers' effect diminishes naturally over time.
Data Source
AI summary
Fuel bundles for nuclear reactors are provided, and can include a fuel element containing U-233, U-235, PU-239, and/or PU-241 fissile material, along with at least two neutron absorbers consisting of Gd, Dy, Hf, Er, and/or Eu, wherein the fissile material(s) and the at least two neutron absorbers are homogeneously mixed in the fuel element. Fuel bundles for nuclear reactors are also provided that include fuel elements having inner elements and outer elements, wherein at least one of the inner elements includes a homogeneous mixture of a fissile material and at least two neutron absorbers. Fuel elements for nuclear reactors are also provided, and can include U-233, U-235, PU-239, and/or PU-241 fissile material, along with at least two neutron absorbers consisting of Gd, Dy, Hf, Er, and/or Eu, wherein the fissile material(s) and the at least two neutron absorbers are homogeneously mixed in the fuel element.