Cylindrical Tank Refueling for Compact Integral Reactors
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Solution Overview
Problem
Traditional refueling methods for nuclear reactors are not applicable to compact, integral reactor designs due to space constraints and contamination concerns, requiring a new approach that ensures efficient and safe refueling without damaging equipment or causing radiation exposure.
Innovation Solution
A method involving the installation of a cylindrical tank on the reactor vessel flange, connecting it to a refueling canal, and using a refueling machine to transfer fuel assemblies from the reactor core to a spent fuel pool, with a radiation shield and filtered air system to manage contamination and radiation exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional refueling method is used with pressurized water reactor, then fuel assemblies can be transferred to spent fuel pool, but the method cannot be applied to compact integral reactor designs due to space constraints and contamination concerns
Solution Approach 1:
The refueling system is segmented into separate functional components: a refueling machine with fuel clamps for fuel handling, a cylindrical tank for water shielding and containment, and a refueling canal for fuel transfer. This segmentation allows each component to be optimized independently and assembled in the compact integral reactor configuration.
Solution Approach 2:
A cylindrical tank filled with water is introduced as an intermediary between the reactor core and the refueling canal. This tank serves multiple functions: providing radiation shielding, containing any potential fuel assembly breaches, and facilitating the transfer of fuel assemblies through its side penetration while preventing contamination of the containment building.
2Ease of operation
If reactor vessel head and upper internals are removed for refueling, then fuel assemblies can be accessed, but equipment and fuel assemblies are exposed to damage and unnecessary radiation exposure
Solution Approach 1:
The refueling machine, cylindrical tank, and associated shielding structures are installed and prepared before the refueling operation begins. The refueling canal is opened and positioned in advance, allowing fuel assemblies to be transferred through a pre-prepared shielded pathway, minimizing the time that fuel and equipment are exposed to radiation.
Solution Approach 2:
The cylindrical tank filled with water acts as an intermediary shielding structure that provides radiation protection during the fuel transfer operation. The water in the tank absorbs radiation, protecting both the fuel assemblies and the refueling equipment from unnecessary radiation exposure while maintaining operational accessibility.
3Object-affected harmful factors
If traditional refueling approach is used with flooding reactor well above vessel flange, then fuel can be transferred under water, but this approach is not practical for compact containment and integral reactor designs
Solution Approach 1:
Instead of flooding the entire reactor containment building with water for shielding, the invention applies water shielding locally within the cylindrical tank. This localized approach provides the necessary radiation protection at the refueling interface while maintaining the compact design and avoiding the complexity of flooding the entire containment structure.
Solution Approach 2:
The refueling system transitions from a horizontal transfer approach (traditional method requiring flooding of the containment building) to a vertical transfer approach through the side penetration of the cylindrical tank. This dimensional change allows fuel assemblies to be transferred upward through the tank and into the refueling canal, simplifying the overall system configuration for compact integral reactors.
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
Enables efficient and precise refueling of compact reactors by providing a temporary refueling pool and shielding, ensuring safe handling and storage of fuel assemblies while minimizing radiation exposure and equipment damage.
Implementation Method 1
A cylindrical tank having an open lower end and an open upper end is installed on the reactor vessel flange... The level of reactor coolant within the reactor vessel is raised to at least partially fill the cylindrical tank
Data Source
AI summary
A method of refueling a nuclear reactor that includes the steps of removing the reactor vessel head and upper internals to a storage location and installing a cylindrical tank having open upper and lower ends, on the reactor vessel flange. The cylindrical tank is sealed to the reactor vessel and a penetration on the side of the cylindrical tank is sealed to a refueling canal that is connected to a spent fuel pool. The level of reactor coolant within the reactor vessel is then raised to at least partially fill the cylindrical tank to a level equal to that of the spent fuel pool. The refueling canal is then opened and a refueling machine supported on the reactor vessel is employed to transfer fuel assemblies between the core and the spent fuel pool.