Combinatorial Heterogeneous-Homogeneous Reactor for 99Mo Production
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Solution Overview
Problem
Conventional methods for producing Technetium-99m (99mTc) using neutron irradiation in nuclear reactors generate large amounts of radioactive waste and suffer from power instabilities due to radiolytic bubble formation and thermal agitation, limiting the specific activity and efficiency of 99Mo production.
Innovation Solution
A combinatorial heterogeneous-homogeneous reactor configuration with a modular reactor core comprising homogeneous fuel assemblies arranged in a regular lattice, utilizing corrosion-resistant alloys and a closed-loop cooling system to manage heat and radiolytic gases, ensuring stable operation and high 99Mo production capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If homogeneous reactor systems are used for 99Mo production, then safety characteristics are improved due to greater radiolytic gas production and negative temperature coefficient, but power instabilities occur due to radiolytic bubble formation and thermal agitation
Solution Approach 1:
The reactor core is divided into multiple heterogeneous zones with different fuel concentrations and compositions. This segmentation allows different regions to contribute differently to the overall power distribution, stabilizing the reactor against power instabilities while maintaining the safety advantages of homogeneous systems.
Solution Approach 2:
Different regions of the reactor core are assigned different fuel properties and concentrations. The local quality varies spatially to optimize both safety characteristics and power stability, with some regions having higher fuel density for power production and others optimized for safety margins.
2Productivity
If conventional target irradiation method is used, then 99Mo production capacity is achieved, but large amounts of radioactive waste are generated
Solution Approach 1:
The reactor operates at optimized power levels and fuel concentrations that maximize 99Mo production efficiency while minimizing waste generation. By changing operational parameters such as neutron flux density and irradiation time, the system achieves high productivity with reduced radioactive waste compared to conventional methods.
3Reliability
If homogeneous fuel assemblies are used, then inherent safety is improved, but power density is limited
Solution Approach 1:
The invention merges the advantages of homogeneous fuel assemblies (inherent safety) with a heterogeneous spatial arrangement that enables higher overall power density. The combination allows the reactor to maintain safety characteristics while achieving the power density needed for high 99Mo production capacity.
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
This configuration enhances the safety and efficiency of 99mTc production by limiting power density, reducing waste generation, and achieving stable operation, thereby meeting high demand while maintaining inherent safety characteristics.
Implementation Method 1
a forced water circulation cooling system
Implementation Method 2
neutron irradiation in a nuclear reactor of a U—Al alloy or electroplated target enriched to 93 wt % 235U
Implementation Method 3
homogeneous mixture of the fuel and moderator
Data Source
AI summary
A combinatorial heterogeneous-homogeneous reactor configuration in which an array or groups of homogeneous fuel assemblies are interlinked together in a heterogeneous lattice. The present invention removes the limitation of a homogeneous reactor by providing a reactor concept that utilizes the inherent advantages of homogeneous fuel elements but in a heterogeneous fuel lattice arrangement that limits the power density of any one homogeneous fuel element and yet forms a reactor arrangement that is capable of producing any product demand of interest. The present invention provides a method for producing medical isotopes by the use of a modular reactor core comprised of homogeneous fuel assemblies arranged in a regular rectangular or triangular pitch lattice. The aqueous fuel solution is contained within individual fuel assemblies that are right circular cylinders clad in corrosion-resistant alloys such as stainless steel, zircalloy, zircalloy alloys, or other metal alloys that are resistant to corrosive fissile environments but preserve neutron economy. The fuel assemblies are supported below by a core plate that is tied directly to the lower reactor support structure. The bottom of each assembly opens into a common plenum area which provides a hydrodynamic communication/coupling path between the individual assemblies in the lattice. The fuel assemblies are supported above by an upper plate that is welded to each assembly tube. The top of each assembly opens to a common upper plenum which provides a means of thermodynamic pressure equalization among the four assemblies in the reactor core lattice.