Nuclear Fuel Debris Container with Flux Trap Segmentation
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Solution Overview
Problem
The safe storage and handling of radioactive debris from nuclear reactors, such as corium and nuclear fuel rod assemblies, pose challenges due to the risk of achieving criticality and the need for effective sub-criticality maintenance during decommissioning and storage processes.
Innovation Solution
Design of specialized containers and baskets with elongated cylindrical bodies and internal flux traps that prevent nuclear criticality by limiting neutron multiplication, allowing for the safe containment and storage of radioactive debris in water or air, with features like neutron absorbers and controlled dimensions to manage hydrogen generation and prevent explosions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the canister dimensions are increased to accommodate more radioactive debris, then the storage capacity is improved, but the risk of achieving nuclear criticality increases
Solution Approach 1:
The canister interior is divided into multiple sectors by flux traps, which physically segment the radioactive debris storage space. This segmentation prevents the formation of continuous fuel paths that could lead to criticality, while still allowing substantial storage capacity through optimized sector arrangement
Solution Approach 2:
The canister dimensions are specifically designed with maximum diameter of 49.5 cm and maximum length of 381.0 cm, which are critical parameters that ensure sub-criticality while maximizing storage capacity. These parameter constraints are derived from nuclear criticality safety calculations
2Ease of manufacture
If the canister is designed with simple cylindrical shape, then the manufacturing ease is improved, but the effectiveness in preventing neutron multiplication may be reduced
Solution Approach 1:
While maintaining the overall simple cylindrical canister shape for ease of manufacture, internal flux traps are introduced to create sector divisions. This combines manufacturing simplicity with effective neutron multiplication control through internal geometric modification
Solution Approach 2:
Flux traps serve as intermediary structures within the simple cylindrical canister, providing the necessary neutron absorption functionality without requiring complex canister geometry. The flux traps mediate between the simple external shape and the complex internal neutron physics requirements
3Reliability
If the canister volume is reduced to ensure sub-criticality, then the nuclear safety is improved, but the storage capacity and productivity are reduced
Solution Approach 1:
The canister is segmented into multiple sectors by flux traps, allowing each sector to store radioactive debris independently. This segmentation enables maximum utilization of the available sub-critical volume, improving storage capacity and productivity while maintaining nuclear safety
Solution Approach 2:
Multiple canisters can be nested or arranged within baskets and overpacks, creating a hierarchical storage system. This nesting approach maximizes the utilization of available storage space while maintaining the sub-critical dimensions of individual canisters
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
Ensures the safe removal and storage of radioactive debris by maintaining sub-critical conditions, preventing nuclear reactions and hydrogen explosions, thereby ensuring the safe handling and long-term storage of nuclear fuel debris.
Implementation Method 1
The flux trap serves to slow down neutron movement, which in turn limits undesired neutron multiplication, thus assuring sub-criticality
Implementation Method 2
The flux trap has open interior regions that may be lined with a neutron absorber
Data Source
AI summary
A container is designed to safely store radioactive debris from, for example, a nuclear reactor meltdown, in water or air. The container, with preferably although not necessarily all metal parts, has an overpack having an elongated cylindrical body extending between a top end and a bottom end, a planar bottom part at the bottom end, an open top at the top end, and a circular planar lid mounted over the open top. A basket is situated inside of the overpack. The basket has a plurality of elongated cylindrical canisters that are in parallel along their lengths. Each of the canisters has an elongated cylindrical body extending between a top end and a bottom end, a planar bottom part at the bottom end, an open top at the top end, and a circular planar lid mounted over the open top.