In-core Instrumentation Removal via Lower Head Extraction
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Solution Overview
Problem
In nuclear reactor maintenance and refueling operations, existing methods compromise radiation safety by requiring operators to be physically close to the reactor core to remove in-core instrumentation, which can lead to increased radiation exposure and prolonged reactor downtime due to the need for cooling before access.
Innovation Solution
An in-core instrumentation system and method that allows for the concurrent removal of instrumentation from the reactor core by removing the lower head of the reactor pressure vessel, maintaining the instrumentation within a sealed reactor module transported to a refueling pool, where it can be withdrawn without breaking the water-tight seal, reducing radiation exposure and minimizing downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If operators physically access the reactor core to remove in-core instrumentation, then the instrumentation can be withdrawn, but operator radiation exposure increases and reactor downtime extends due to required cooling periods
Solution Approach 1:
A robotic manipulator system serves as an intermediary between the operator and the radioactive reactor core. The manipulator performs Swagelok fitting loosening and instrumentation withdrawal operations remotely, allowing operators to control the process from a shielded location while the manipulator handles the radioactive components inside the reactor vessel
Solution Approach 2:
The patent replaces manual mechanical operations with an automated robotic system. The manipulator uses motorized actuators and automated control systems to perform the mechanical tasks of loosening Swagelok fittings and withdrawing instrumentation, eliminating the need for operators to be physically present in the high-radiation zone
2Loss of time
If operators access the reactor core immediately after shutdown, then instrumentation can be removed quickly, but radiation levels remain high increasing exposure risk
Solution Approach 1:
The robotic manipulator system is pre-positioned and prepared for operation before the reactor shutdown is complete. The system is ready to immediately begin instrumentation withdrawal operations as soon as the reactor reaches a safe state, eliminating delays associated with manual setup and operator positioning
3Ease of operation
If multiple in-core instruments are removed sequentially by hand, then each instrument can be carefully withdrawn, but the process time extends significantly
Solution Approach 1:
The robotic manipulator system combines multiple operations into a single integrated process. The manipulator can handle multiple Swagelok fittings and withdraw multiple instrumentation assemblies in a continuous automated sequence, merging what would otherwise be separate manual operations into one efficient process
Data Source
AI summary
A nuclear reactor module, comprising a reactor pressure vessel including a removably attached lower reactor vessel head configured to house a reactor core; a lower reactor vessel head removably attached to the reactor pressure vessel and configured to house the reactor core; a containment vessel encapsulating the reactor pressure vessel; and a lower containment head removably attached to the containment vessel and configured to house the lower reactor vessel head, the containment vessel and the reactor pressure vessel being configured to be lifted and transported between a reactor bay and a refueling bay within a nuclear reactor building via a crane.