Neutron Sealed Source Thermal Management
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Solution Overview
Problem
The existing neutron sources using Californium-252 and Palladium cermet wires in nuclear reactors face heat-related integrity issues due to fission and decay heat, which can cause the cermet wires to melt, risking capsule integrity.
Innovation Solution
A stainless steel block with separate blind apertures is used to house the cermet wires, acting as a heat sink and separator to prevent wire contact and manage heat generated during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple cermet wires are placed in a single source cavity, then the neutron source can be compact and simple in structure, but the heat generated from fission and decay can melt the cermet wires and compromise capsule integrity
Solution Approach 1:
The single source cavity is divided into multiple separate blind apertures within the stainless steel block. Each cermet wire is housed in its own isolated aperture, preventing direct contact between wires while distributing heat generation across separate compartments. This segmentation maintains structural simplicity while eliminating the melting risk through thermal isolation.
2Ease of manufacture
If cermet wires are loosely placed in a source cavity, then the source can be easy to manufacture, but the wires may touch each other and generate excessive heat that melts the wires
Solution Approach 1:
The stainless steel block with blind apertures serves as an intermediary structure between the cermet wires and the external environment. This intermediary provides mechanical support and thermal management, conducting heat away from the wires through the stainless steel material while maintaining easy assembly by simply inserting wires into pre-formed apertures.
3Temperature
If cermet wires are isolated in separate blind apertures, then heat from fission and decay can be rejected through the stainless steel block, but the source capsule structure becomes more complex
Solution Approach 1:
The stainless steel block performs multiple functions simultaneously: it provides structural support for the cermet wires, acts as a heat sink through its thermal conductivity, serves as a containment vessel, and provides mechanical strength to the capsule. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in overall structural complexity while achieving effective heat rejection.
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 mitigates the risk of melting by isolating and dissipating heat, ensuring the integrity of the neutron source capsule and maintaining reliable reactor operation.
Implementation Method 1
rejecting internally generated fission and decay heat from the cermet wire sources through the stainless steel block
Implementation Method 2
relying solely on spontaneous fission or delayed fission within the reactor fuel rods
Implementation Method 3
heat from both fission and decay
Data Source
Figure 1~4
Figure 5~6
Figure 7~11
AI summary
A neutron sealed source (10) holds cermet wire sources (200), such as Californium-252/Palladium wires, in separate blind apertures (20, 22, 24, 26) within a stainless steel block (14). The stainless steel block is part of an inner encapsulation (12) and includes blind apertures arranged in rotational symmetry for receiving the cermet wire sources. The cermet wire sources are separated from each other and the fission and decay heat is rejected through the stainless steel block.