External Annular Steam Generator for Compact PWR
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Solution Overview
Problem
The integral Pressurized Water Reactor (PWR) design with an internal steam generator increases the size of the pressure vessel, leading to higher manufacturing and transport costs, complex site considerations, and safety concerns due to larger vessel dimensions and potential seal integrity issues.
Innovation Solution
The design incorporates an annular steam generator positioned outside the pressure vessel but secured with it, featuring tubes with ends in fluid communication with the sealed vessel volume and a secondary coolant flow volume that is not in fluid communication, allowing for efficient heat transfer and compact reactor geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the steam generator is placed inside the pressure vessel (integral PWR design), then the primary coolant water remains contained within the pressure vessel and the reactor structure is integrated, but the size of the pressure vessel increases leading to higher manufacturing cost, transport cost, and safety concerns
Solution Approach 1:
The steam generator is repositioned from an internal to an external location, utilizing the vertical dimension above the pressure vessel rather than occupying horizontal space within it. This dimensional relocation allows the steam generator to remain functionally integrated while eliminating the volume increase penalty, resolving the contradiction between containment integrity and pressure vessel size.
2Device complexity
If the steam generator is placed inside the pressure vessel, then integration is achieved, but manufacturing cost and transport cost increase due to larger vessel dimensions
Solution Approach 1:
The reactor system is segmented into distinct functional modules: the pressure vessel containing the reactor core and primary coolant circuit, and the steam generator as a separate but integrated component positioned above. This segmentation allows each module to be manufactured and transported independently at standard sizes, reducing manufacturing and transport costs while maintaining functional integration through controlled fluid connections.
Solution Approach 2:
The steam generator is relocated to the vertical space above the pressure vessel, utilizing the unused vertical dimension rather than expanding the horizontal footprint. This allows the pressure vessel to maintain its original manufacturing size while achieving integration benefits, resolving the contradiction between device integration and ease of manufacture.
3Volume of stationary object
If the steam generator is placed inside the pressure vessel, then the reactor is compact, but site considerations become more complex and safety maintenance becomes more difficult
Solution Approach 1:
By segmenting the steam generator as a separate module positioned above the pressure vessel, the design maintains a compact overall footprint while allowing independent access to the steam generator for maintenance and safety inspections. This segmentation resolves the contradiction between compact volume and ease of operation by separating the compact containment function from the accessible maintenance function.
4Device complexity
If the steam generator is placed inside the pressure vessel, then primary coolant flow circuit is simplified, but the pressure vessel size increases
Solution Approach 1:
The steam generator is positioned in the vertical dimension above the pressure vessel, allowing the primary coolant flow circuit to remain simplified with direct thermal coupling while the pressure vessel maintains its original size. The coolant flows vertically through the pressure vessel and thermally couples to the externally positioned steam generator, achieving circuit simplicity without volume penalty.
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
This configuration reduces the vertical height of the pressure vessel, simplifies installation and maintenance, and maintains safety while minimizing the reactor's overall volume, enabling higher thermal power capacity in a more compact form.
Implementation Method 1
Heat (i.e., energy) is transferred from the reactor core to the secondary coolant water via the intermediary of the primary coolant water
Implementation Method 2
secondary coolant water is flowed in thermal communication with the primary coolant water
Implementation Method 3
Primary coolant water heated by the reactor core naturally tends to rise through the pressure vessel as it cools (the 'hot leg' of the primary circuit)
Implementation Method 4
Primary coolant water heated by the reactor core naturally tends to rise through the pressure vessel as it cools
Data Source
AI summary
A pressurized water reactor (PWR) includes a cylindrical pressure vessel defining a sealed volume, a nuclear reactor core disposed in a lower portion of the cylindrical pressure vessel, one or more control rod drive mechanisms (CRDMs) disposed in the cylindrical pressure vessel above the nuclear reactor core, and an annular steam generator surrounding the nuclear reactor core and the CRDM. In some such PWR, a cylindrical riser is disposed coaxially inside the pressure vessel and inside the annular steam generator and surrounds the nuclear reactor core and the CRDM, and the steam generator is disposed coaxially inside the cylindrical pressure vessel in an annular volume defined by the cylindrical pressure vessel and the cylindrical riser. In other such PWR, the steam generator is disposed coaxially outside of and secured with the cylindrical pressure vessel.