Molten Salt Reactor Solid Neutron Moderator Design
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Solution Overview
Problem
Molten Salt Nuclear Reactors face challenges with neutron leakage and damage to the outer vessel due to the lack of effective neutron moderation, leading to complex design requirements and limited reactor utility without bulk moderators like graphite, which have limited lifetimes and safety concerns.
Innovation Solution
A Single Fluid Molten Salt Nuclear Reactor design incorporating a solid neutron moderator with salt coolant channels creates an inner zone with a thermalized neutron spectrum, reducing neutron leakage and damage by maintaining a k-effective value of just over 1.0, eliminating the need for bulk moderators and simplifying the design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If bulk moderators like graphite are used throughout the core, then neutron spectrum softening is achieved allowing operation with less fissile material, but reactor design complexity increases and safety concerns arise from limited lifetime and fire hazard
Solution Approach 1:
The patent extracts and removes bulk graphite moderators from the reactor core design, eliminating their associated safety hazards and lifetime limitations while maintaining neutron spectrum softening through alternative means (molten salt composition and geometry-based moderation)
Solution Approach 2:
The patent changes the physical state and distribution parameters of the moderator from solid bulk graphite to dissolved/modulated state within the molten salt fuel itself, achieving neutron spectrum control without separate moderator materials
2Loss of energy
If bulk moderators are used throughout the core, then neutron leakage is reduced, but neutron induced damage on the reactor vessel increases due to lack of effective moderation at outer zones
Solution Approach 1:
The patent implements local quality differentiation by creating distinct zones within the core: an inner moderated zone with thermalized neutrons and an outer unmoderated zone with faster neutrons, allowing each region to serve its specific function (fuel consumption vs. neutron reflection)
Solution Approach 2:
The patent segments the core into functional zones (inner moderated region and outer unmoderated region) with different neutron spectrum characteristics, allowing optimized performance for both neutron economy and vessel protection
3Loss of energy
If reflector material is added between core and vessel wall, then neutron leakage is reduced, but device complexity increases and proliferation resistance decreases
Solution Approach 1:
The patent merges the reflector function with the fertile blanket salt surrounding the core, combining neutron reflection and fertile material storage into a single integrated component, eliminating separate reflector assemblies and reducing design complexity
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 design significantly reduces neutron flux at the outer vessel wall, minimizing damage and neutron loss, improving the breeding ratio and reactor control, while avoiding the complexities and safety issues associated with bulk moderators, and allowing for a practical reactor with a longer core residency time.
Implementation Method 1
A Single Fluid Molten Salt Nuclear Reactor design incorporating a solid neutron moderator with salt coolant channels creates an inner zone with a thermalized neutron spectrum
Implementation Method 2
a pump to circulate a molten salt in the vessel, the support structure, the neutron moderator, and the pump being arranged to circulate the molten salt through the at least one through hole of the neutron moderator
Implementation Method 3
a pump to circulate a molten salt in the vessel
Implementation Method 4
molten salt in the vessel, the support structure, the neutron moderator
Data Source
AI summary
A Single Fluid Reactor with an inner zone that includes a solid neutron moderator, which can have through holes defined therein. This solid neutron moderator can have a relatively small diameter, which can range, in some embodiments, from less than one meter to about 1.5 meter. The solid neutron moderator effectively creates an inner zone with a neutron profile that is far more thermalized than if the solid neutron moderator were absent. The surrounding layer of salt surrounding this inner zone has a much harder neutron spectrum.