How a Molten Metal Buffer Improves Heat Transfer in Nuclear Reactors
This patent describes a nuclear fission reactor design that uses a liquid molten metal to fill gaps between the nuclear fuel and its protective casing, improving heat transfer and reactor safety.
Original patent title: “Molten metal fuel buffer in fission reactor and method of manufacture”
This patent describes a nuclear fission reactor design that uses a liquid molten metal to fill gaps between the nuclear fuel and its protective casing, improving heat transfer and reactor safety. Granted to BWXT Advanced Technologies in 2024 with 23 claims, and it is expected to expire in 2040.
Coverage
What does this patent actually cover?
This fission reactor design improves how heat moves from the nuclear fuel to the cooling system. Each 'heat generating source,' which is the nuclear fuel, is encased by a 'cladding' (ClaimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 1). Instead of directly touching, a 'molten metal' fills the space between the fuel and the cladding (Claim 2). This molten metal, which can be sodium or lead-bismuth (Claim 10), acts as a thermal buffer, ensuring excellent heat transfer contact (AbstractabstractA short summary at the front of the patent describing the invention. Not legally binding.Read more →). The cladding itself has a specific shape, described as a 'hyperboloid of one sheet' in cross-section (Claim 1), which helps define the coolant channels around it. For example, if a small gap forms between the fuel and cladding due to heating or cooling, the liquid molten metal will flow to fill that gap, maintaining consistent heat transfer.
The gap
What does this patent NOT cover?
- Does not cover reactor designs where the nuclear fuel directly contacts the cladding without an intervening molten metal layer.
- Does not cover designs where the cladding does not have a cross-sectional shape of a hyperboloid of one sheet.
- Does not cover reactors that use a gas or solid material, rather than a molten metal, to fill the space between fuel and cladding.
- Does not cover fission reactors where the molten metal is not in thermal transfer contact with both the heat generating source and the cladding.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
The noveltynoveltyThe requirement that an invention be different from anything publicly known before its priority date.Read more → lies in using a molten metal as a dynamic thermal buffer that fills any void space between the fuel and cladding, combined with a specific 'hyperboloid of one sheet' cladding shape. This ensures continuous, efficient heat transfer even as components expand or contract, which is a common challenge in high-temperature environments.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Advanced small modular reactors (SMRs)
Molten salt reactors (MSRs) with solid fuel pins
Liquid metal fast breeder reactors (LMFBRs)
Future high-temperature gas reactors (HTGRs) with liquid metal heat pipes
Why it matters
The bigger picture
Efficient heat transfer is critical in nuclear reactors to prevent overheating and ensure safe operation. This design aims to provide a more reliable and consistent thermal connection between the fuel and the coolant system. By using a molten metal buffer, it addresses potential issues like gaps forming between fuel and cladding, which can hinder heat removal and lead to localized hot spots. This could contribute to the development of safer and more efficient advanced nuclear reactor designs.
Filed
April 17, 2020
Granted
March 26, 2024
Market context
Who's building on this
Companies in this space
BWXT Advanced Technologies LLC, the assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →, is a major player in nuclear energy, focusing on advanced nuclear reactors and fuel. Companies developing advanced reactor concepts, particularly small modular reactors (SMRs) and other Generation IV designs, are actively exploring novel heat transfer and fuel element designs. These include companies like TerraPower and Oklo, which are developing liquid metal-cooled reactors, where such a buffer could be relevant.
Market impact
This patent contributes to the ongoing evolution of nuclear reactor technology, particularly in the realm of advanced and small modular reactors. By offering a solution for improved heat transfer and thermal management, it could enable more compact, efficient, and potentially safer reactor designs. While not creating a new market category, it refines core components, potentially influencing the design choices for next-generation nuclear power plants and enhancing their economic viability and safety profiles.
Claim 1 — Plain English
What this patent covers
This fission reactor design improves how heat moves from the nuclear fuel to the cooling system. Each 'heat generating source,' which is the nuclear fuel, is encased by a 'cladding' (Claim 1). Instead of directly touching, a 'molten metal' fills the space between the fuel and the cladding (Claim 2). This molten metal, which can be sodium or lead-bismuth (Claim 10), acts as a thermal buffer, ensuring excellent heat transfer contact (Abstract). The cladding itself has a specific shape, described as a 'hyperboloid of one sheet' in cross-section (Claim 1), which helps define the coolant channels around it. For example, if a small gap forms between the fuel and cladding due to heating or cooling, the liquid molten metal will flow to fill that gap, maintaining consistent heat transfer.
The clever bit
The novelty lies in using a molten metal as a dynamic thermal buffer that fills any void space between the fuel and cladding, combined with a specific 'hyperboloid of one sheet' cladding shape. This ensures continuous, efficient heat transfer even as components expand or contract, which is a common challenge in high-temperature environments.
What it does not cover
- Does not cover reactor designs where the nuclear fuel directly contacts the cladding without an intervening molten metal layer.
- Does not cover designs where the cladding does not have a cross-sectional shape of a hyperboloid of one sheet.
- Does not cover reactors that use a gas or solid material, rather than a molten metal, to fill the space between fuel and cladding.
- Does not cover fission reactors where the molten metal is not in thermal transfer contact with both the heat generating source and the cladding.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
Patent enters public domain
PatentBrief Score
Impact Score
Early stage
Citation count
0/40
No citations yet
Claim breadth
15/20
Broad claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
20/20
Granted within 5 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$35K – $112K
Midpoint $70K · 13.5 yr remaining · industry ×1.5
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Claim text not yet imported for this patent
The original legal language
Original claims
23 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
GRAMLICH, C. D. (2024). How a Molten Metal Buffer Improves Heat Transfer in Nuclear Reactors (U.S. Patent No. 11,942,229). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/11942229/molten-metal-fuel-buffer-in-fission-reactor-and-method-of-manufacture
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
Embed
Add this patent to your site
Drop this plain-English patent card into any blog post or article — free, no signup. It always links back to the full breakdown here.
<div data-patentlens-widget data-patent-number="US11942229"></div> <script src="https://patentbrief.org/embed.js" async></script>
Stay in the loop
Get a weekly digest of new patents.
One email per week. No spam. Unsubscribe anytime.
Keep exploring
Related patents you should know
US 4683195 · 1987
How to Make Billions of Copies of a DNA Segment
This patent describes the Polymerase Chain Reaction (PCR), a method to rapidly create many copies of a specific piece of DNA or RNA, enabling its detection and analysis.
Cetus Corp
US 8697359 · 2014
How to Edit Genes in Human Cells Using an Engineered CRISPR System
This patent describes an engineered CRISPR-Cas9 system for precisely cutting DNA in eukaryotic cells to change how genes work, opening the door for gene editing in complex organisms.
Massachusetts Institute of Technology
US 7657849 · 2010
How the iPhone's Slide-to-Unlock Gesture Works
Apple's 2010 patent describes unlocking a device by dragging a specific graphical image across the touchscreen along a predefined path, a gesture that became iconic with the original iPhone.
Apple Inc
US 4733665 · 1988
How Doctors Implant a Permanent Stent Using a Balloon
This patent describes the method for placing a permanent, expandable wire mesh tube inside a blood vessel or other body tube using a balloon-tipped catheter to widen it and keep it open.
Expandable Grafts Partnership
US 4965188 · 1990
How to Make Many Copies of a DNA Piece with Heat
This patent describes the Polymerase Chain Reaction (PCR) method, a technique to make millions of copies of a specific DNA segment using a heat-resistant enzyme and repeated temperature changes.
Cetus Corp
US 4235871 · 1980
How to Encapsulate Active Materials in Lipid Bubbles Efficiently
This patent describes a method for trapping biologically active substances inside tiny, multi-layered fat bubbles called liposomes, using a specific water-in-oil emulsion and gel-forming process to improve how much material gets captured.
Individual
Semantically similar
You might also find these interesting
US 11495363 · 2022 · BWXT Advanced Technologies
How a Portable Nuclear Reactor Stays Stable During Operation
US 12073952 · 2024 · BWXT Technical Services Group
Using Gas Pressure to Safely Control Liquid Fuel Nuclear Reactors
US 11728052 · 2023 · Terra Power
TerraPower's Molten Salt Reactor with Internal Heat Exchangers
US 10475543 · 2019 · Ultra Safe Nuclear
How to Make Meltdown-Proof Nuclear Fuel Pellets
More to explore
More in Energy & Clean Tech
US RE49155 · 2022 · Halliburton Energy Services Inc
Electric or Natural Gas Blending and Pumping for Oil Wells
US 11436484 · 2022 · Nvidia Corp
Nvidia's Method for Training Self-Driving Car AI in Simulations
US 11840398 · 2023 · Titan Trailers Inc
How Titan Trailers Builds Stronger, Smoother Cargo Containers
US 2708656 · 1955
How the First Nuclear Reactor Works
New to patents?
Common Questions
Frequently Asked Questions
What does How a Molten Metal Buffer Improves Heat Transfer in Nuclear Reactors cover?
This patent describes a nuclear fission reactor design that uses a liquid molten metal to fill gaps between the nuclear fuel and its protective casing, improving heat transfer and reactor safety.
Who owns patent US 11942229?
BWXT Advanced Technologies owns this patent, granted in 2024.
When does this patent expire?
This patent is expected to expire on April 17, 2040, when the invention enters the public domain.
What problem does this patent solve?
Efficient heat transfer is critical in nuclear reactors to prevent overheating and ensure safe operation. This design aims to provide a more reliable and consistent thermal connection between the fuel and the coolant system. By using a molten metal buffer, it addresses potential issues like gaps forming between fuel and cladding, which can hinder heat removal and lead to localized hot spots. This could contribute to the development of safer and more efficient advanced nuclear reactor designs.
What does this patent NOT cover?
Does not cover reactor designs where the nuclear fuel directly contacts the cladding without an intervening molten metal layer.
Same assignee
More from BWXT Advanced Technologies
Patent monitoring