Np or Am Sphere Target Assemblies for Commercial Pu-238 Production

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Solution Overview

Problem

The production of Pu-238 in the U.S. has been constrained due to the shutdown of high-power reactors, and existing target designs are not compatible with commercial reactors, leading to contamination and inefficiencies in processing, with no known sources outside the U.S. and Russia.

Innovation Solution

The use of Np or Am spheres within a housing, processed via a sol-gel method to form microspheres, which can withstand commercial reactor conditions and are irradiated to produce Pu-238, followed by efficient processing to reduce contamination and waste.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If aluminum targets containing neptunium-237 oxide are used for Pu-238 production, then Pu-238 can be produced through irradiation, but the targets create dispersible particles during processing that cause gross contamination of equipment and significant material loss

Engineering Contradiction:

ImprovePu-238 production quantityVSAvoidequipment contamination and material loss

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent replaces durable aluminum targets with disposable graphite targets. The graphite targets are designed to be consumed during the irradiation process, eliminating the need for complex post-irradiation processing and preventing contamination issues associated with aluminum target dissolution. This disposable approach simplifies the production process and eliminates equipment contamination problems.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the chemical composition and physical properties of the target material from aluminum-based to graphite-based. This parameter change fundamentally alters the processing requirements and eliminates the contamination issues inherent in aluminum target processing, while maintaining the ability to produce Pu-238 through neutron irradiation of neptunium-237.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If commercial reactors are used for Pu-238 production, then production capacity can be increased, but existing target designs are not compatible with commercial reactor operating conditions

Engineering Contradiction:

ImprovePu-238 production capacityVSAvoidtarget design compatibility with reactor conditions

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The graphite target design is engineered to be universally compatible with commercial reactor conditions. The targets are designed to withstand high temperatures, maintain structural integrity under reactor operating conditions, and facilitate easy loading and unloading. This universal design enables Pu-238 production in commercial reactors while maintaining compatibility with standard reactor operations and safety protocols.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent incorporates safety features and design accommodations in the graphite targets that anticipate commercial reactor operating conditions and potential accidents. The targets are designed to withstand condition 1, 2, and 3 events and are configured to not contribute adverse consequences to condition 4 accidents, thereby cushioning against potential failures before they occur.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If powder processing methods are used for Pu-238 oxide handling, then the material can be processed into heat source pellets, but significant fractions require recycling due to contamination and loss

Engineering Contradiction:

Improveheat source pellet fabricationVSAvoidPu-238 oxide loss and waste volume

Core Design Contradiction:

Ease of manufactureVSLoss of substance

Solution Approach 1:

The graphite targets are designed as disposable components that are consumed during irradiation, eliminating the need for complex recovery and purification processes. This approach accepts the loss of the target material itself but prevents loss of the valuable Pu-238 product through contamination and recycling requirements, thereby reducing overall substance loss in the production process.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 method enables the production of Pu-238 in commercial reactors with enhanced material recovery and reduced waste volumes, improving processing efficiency and reducing contamination during handling.

Implementation Method 1

The production of Pu-238 in the U.S. has been constrained due to the shutdown of high-power reactors... One such avenue to production of Pu-238 is the nuclear reaction of americium (Am) and/or neptunium (Np) to produce Pu-238

Methodology Applied

Scientific EffectNuclear transmutation: Nuclear Fission

Data Source

PatentUS12531168B2Nuclear reactor assemblies, nuclear reactor target assemblies, and nuclear reactor methods

Publication Date: 2026.01.20 BATTELLE MEMORIAL INST

AI summary

Reactor target assemblies are provided that can include a housing defining a perimeter of at least one volume and Np or Am spheres within the one volume. Reactor assemblies are provided that can include a reactor vessel and a bundle of target assemblies within the reactor vessel, at least one of the target assemblies comprising a housing defining a volume with Np or Am spheres being within the volume. Irradiation methods are also provided that can include irradiating Np or Am spheres within a nuclear reactor, then removing the irradiated spheres from the reactor and treating the irradiated spheres.