Reactor Core Cartridge Support to Limit Seismic Control Rod Shift
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Solution Overview
Problem
Nuclear reactors face challenges in maintaining core stability and minimizing relative motion between the reactor core and control elements, particularly during seismic events, due to the flexibility of the reactor vessel support structure, which can affect reactivity coefficients.
Innovation Solution
A reactor support system where the reactor core is supported by a cartridge that hangs from the reactor vessel head, coupling the load path of both the core and control elements to a common support structure, reducing potential relative movement and transmitting the core weight directly to external supporting structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the reactor core is supported by the reactor vessel, then the vessel must be robust to support heavy loads, but this increases the flexibility of the support structure and allows relative motion between core and control elements during seismic events
Solution Approach 1:
The invention divides the support system into separate functional components: the reactor vessel supports only its own weight and coolant, while a dedicated core support structure (cartridge assembly) supports the reactor core and control elements. This segmentation allows each component to be optimized independently, with the core support structure providing rigid support that minimizes relative motion during seismic events.
Solution Approach 2:
The cartridge assembly acts as an intermediary between the reactor core and the reactor vessel. It provides a rigid support structure that couples the load paths of both the core and control elements to a common support structure, reducing relative movement while still allowing the vessel to be supported from the side or bottom.
2Adaptability or versatility
If the reactor vessel is supported from the side or bottom, then the vessel can be more flexible, but this flexibility causes the core to move relative to control elements during seismic events, affecting reactivity
Solution Approach 1:
The support system is segmented into independent functions: the vessel support structure provides flexibility for seismic adaptation, while the cartridge assembly provides rigid support for the core and control elements. This segmentation allows the vessel to be supported from the side or bottom without compromising core stability.
Solution Approach 2:
The cartridge assembly serves as an intermediary that decouples the vessel support flexibility from the core support rigidity. It provides a stable platform for the core and control elements regardless of how the vessel itself is supported, ensuring reactivity control stability even when the vessel moves during seismic events.
3Reliability
If control elements are supported from the vessel head, then safety is improved as failed controls fall into the core to reduce reactivity, but the weight of control elements adds to the vessel head load
Solution Approach 1:
The cartridge assembly acts as an intermediary support structure that carries the weight of both the control elements and the reactor core. This relieves the vessel head of the cumulative load while maintaining the safety advantage of overhead support, as the control elements still hang from the vessel head region but their weight is transferred to the cartridge assembly.
Data Source
AI summary
A nuclear reactor is designed to couple the load path of control elements with the reactor core, thus reducing opportunity for differential movement between the control elements and the reactor core. A core barrel can be fabricated in a manufacturing facility to include the reactor core, control element supports, and control element drive system. The core barrel can be mounted to a reactor vessel head. Movement, such as through seismic forces, transmits an equal direction and magnitude to the control elements and the reactor core, thus inhibiting the opportunity for differential movement.