Modular Neutron Shielding Ring for Spent Nuclear Fuel Storage
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Solution Overview
Problem
Existing thermally conductive casks for storing spent nuclear fuel suffer from inadequate heat removal and vulnerability to radiation escape, with limited flexibility in design and manufacturing without significant redesign or retooling.
Innovation Solution
A radiation shielding ring system that surrounds the containment cavity, providing enhanced gamma and neutron radiation shielding while facilitating improved heat conduction and neutron absorption, with a stacked assembly design and voids for neutron absorbing material to prevent radiation escape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If thermally conductive casks are used for storing spent nuclear fuel, then heat removal capability is improved, but vulnerability to radiation escape increases and design flexibility is limited
Solution Approach 1:
The cask body is divided into multiple modular segments (first body segment, second body segment, third body segment) that can be assembled together. Each segment contains internal structures such as fuel assembly holders, shadow shields, and thermal conduction elements. This segmentation allows the thermal conduction pathways to be distributed across multiple components while maintaining radiation shielding integrity through proper material selection and arrangement in each segment.
Solution Approach 2:
The cask employs composite material construction with different materials serving different functions: high thermal conductivity materials (such as aluminum or copper) are used for thermal conduction elements and fuel assembly holders to improve heat removal, while high-density radiation shielding materials (such as steel, lead, or depleted uranium) are used for the cask body walls and shadow shields to prevent radiation escape. The composite structure integrates both thermal conduction and radiation shielding requirements.
2Temperature
If thermally conductive casks are used for storing spent nuclear fuel, then heat removal capability is improved, but design flexibility and manufacturing adaptability deteriorate
Solution Approach 1:
The cask is designed as a modular assembly of standardized segments that can be configured in different arrangements. The fuel assembly holders, shadow shields, and thermal conduction elements are separate replaceable components within the cask body segments. This modular design allows different numbers and types of fuel assemblies to be accommodated by reconfiguring the internal components without redesigning the entire cask structure, thereby improving design flexibility and manufacturing adaptability.
Solution Approach 2:
The cask design incorporates universal components that serve multiple functions: the cask body segments provide both structural support and radiation shielding; the fuel assembly holders provide both fuel positioning and thermal conduction pathways; the shadow shields provide both radiation shielding and structural separation between fuel assemblies. This multi-functionality allows a single cask design to accommodate different fuel types and configurations, enhancing versatility.
3Reliability
If radiation shielding is enhanced to prevent neutron and gamma radiation escape, then radiation containment safety is improved, but heat removal capability deteriorates
Solution Approach 1:
The cask employs local quality differentiation by using high-density radiation shielding materials (steel, lead, depleted uranium) for the cask body walls and shadow shields where radiation containment is critical, while using high thermal conductivity materials (aluminum, copper) for the fuel assembly holders, internal support structures, and thermal conduction elements where heat removal is critical. This localized material selection optimizes both radiation shielding and thermal conduction in their respective regions without compromising overall performance.
Solution Approach 2:
The cask design features nested structures where fuel assemblies are positioned within fuel assembly holders, which are in turn positioned within the cask body segments. Shadow shields are nested between fuel assemblies to provide localized radiation shielding. The thermal conduction elements are nested within the fuel assembly holders to provide thermal pathways. This nested arrangement allows radiation shielding and thermal conduction functions to be integrated at different hierarchical levels, achieving both radiation containment and heat removal simultaneously.
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 solution effectively enhances radiation shielding and heat removal from spent nuclear fuel, improving safety and flexibility in cask design without requiring extensive redesign or retooling, while maintaining continuous surface contact for efficient heat conduction.
Implementation Method 1
thermally conductive casks utilize thermal conduction to cool the SNF. More specifically, the cask body itself is designed to lead the heat away from the SNF via thermal conduction
Implementation Method 2
The radiation shielding ring provides improved gamma and neutron radiation shielding properties while facilitating improved cooling of the HLW inside the cavity by effectively conducting heat away from the HIM
Implementation Method 3
The radiation shielding ring provides improved gamma and neutron radiation shielding properties
Data Source
AI summary
An apparatus, system and method for storing high level radioactive waste. In one aspect, the invention is a specially designed ring structure for providing neutron and gamma radiation shielding for high level radioactive materials that produce residual heat. A plurality of the ring structures may be arranged in a stacked assembly that completely surrounds an internal containment boundary. Collars may be provided at the ring-to-ring interfaces. The ring structures may have voids which are configured for receiving neutron absorbing material that completely surrounds the containment boundary.