PWR Steam Generator Technology Landscape 2026 — PatSnap Eureka
PWR Steam Generator Technology Landscape 2026
From integral SMR designs to industrial cogeneration, PWR steam generator innovation is accelerating. This report maps patent clusters, key assignees, and emerging application domains from 1971 to 2026.
How PWR Steam Generator Innovation Has Evolved
PWR steam generators function as shell-and-tube heat exchangers where pressurized primary coolant at approximately 15.5 MPa and 320°C flows through tube bundles, transferring heat to secondary-side feedwater and producing steam for turbines or industrial users. Two dominant configurations appear in this dataset: recirculating steam generators with U-tube bundles and once-through steam generators that convert feedwater directly to superheated steam in a single pass.
Foundational designs from Kraftwerk Union AG and Siemens Aktiengesellschaft established the standard U-tube and straight-tube bundle architectures, documented in patents from 1971 through 1978. These early records are broadly inactive, reflecting mature and commoditized technology that forms the baseline for all subsequent architectural development.
The dataset reveals a strong pivot toward integral PWR designs embedding OTSGs inside the pressure vessel, with BWXT filing a dense patent family for the mPower compact integral PWR across US, CA, EP, and WO jurisdictions between 2012 and 2020. This period shows the highest filing density for structural innovation in the dataset.
The most recent cluster, dominated by Chinese assignees from 2019 through January 2026, addresses PWR secondary steam for industrial process heat supply — coupling nuclear steam to chemical plants, pharmaceutical facilities, and petrochemical refineries to replace coal boilers. This cogeneration wave represents the leading edge of current innovation activity.
Patent Filing Density Across Technology Clusters and Time Periods
Analysis of retrieved records shows three distinct filing eras — foundational designs (1971–1990), safety and simulation development (1989–1998), and the integral SMR and cogeneration wave (2010–2026) — each dominated by a different geographic and institutional cohort.
PWR Steam Generator Patent Records by Technology Cluster
The integral OTSG / compact SMR cluster holds the largest single-assignee family in the dataset, reflecting BWXT’s multi-jurisdiction filing strategy, while the cogeneration cluster is the most geographically concentrated in China.
↗ Click bars to explorePWR Steam Generator Patent Filing Activity by Era (Records Count)
The 2010–2026 period accounts for the majority of retrieved records, driven first by Western SMR integral designs and then by Chinese cogeneration filings peaking in 2022–2026.
↗ Click bars to exploreKey PWR Steam Generator Application Domains and Deployment Contexts
Retrieved records span six distinct application domains — from traditional baseload power generation to nuclear fusion — reflecting PWR steam generator technology’s expanding role beyond electricity production.
PWR Baseload Electricity Generation
Classical and compact PWR steam generators deliver saturated or lightly superheated steam at typically 6–7 MPa to the turbine-generator. A 2017 literature record documents heat transfer correlations, RELAP5 transient simulation, and regulatory requirements for maintaining the primary-secondary boundary in operational nuclear power plants.
Power GenerationPWR Industrial Process Steam Supply
Chinese assignees including China Nuclear Power Engineering Co., Ltd., SNERDI, and Jiangsu Nuclear Power Co., Ltd. are filing systems routing PWR secondary steam through isolation heat exchangers to supply chemical plants, pharmaceutical facilities, and petrochemical refineries. Jiangsu Nuclear Power’s 2022 CN filing extends this to a triple-product system producing electricity, industrial steam, and desalinated water simultaneously.
Industrial CogenerationSmall Modular Reactor Remote Power
BWXT’s mPower integral PWR patents explicitly target smaller-footprint deployments with an annular OTSG embedded inside the pressure vessel, filed across US, CA, EP, and WO jurisdictions from 2012 to 2020. China Institute of Atomic Energy Design (CIAE) filed a 2022 CN patent for a miniature fully natural-circulation PWR with a large-coil steam generator targeting border regions, polar areas, plateaus, and distant islands.
SMR DeploymentEU DEMO Fusion Reactor Steam System
ENEA-led EU DEMO WCLL reactor studies published in 2023 specifically select OTSGs for fusion balance-of-plant because their lower thermal inertia better accommodates plasma pulsed regimes and dwell-period decay power levels. The STEAM test facility at Brasimone is under construction to experimentally validate this approach, representing the first systematic extension of PWR-heritage OTSG technology to fusion applications.
Nuclear FusionLeading Patent Assignees in PWR Steam Generator Technology
Innovation is moderately concentrated: BWXT/Babcock & Wilcox dominates Western SMR-focused filings with 9+ records across US, CA, EP, and WO, while Chinese industrial assignees collectively account for approximately 18–20 CN-jurisdiction records from 2019 to 2026.
Top PWR Steam Generator Assignees by Approximate Record Count
↗ Click bars to exploreBWXT / Babcock & Wilcox
BWXT Foreign Holdings, LLC and BWXT mPower, Inc. hold 9+ records spanning US, CA, EP, and WO jurisdictions filed between 2012 and 2020, covering the mPower compact integral PWR with an annular once-through steam generator inside the pressure vessel. Key patents include the 2016 US annular OTSG with vertical tubes and natural circulation primary flow, and the 2017 EP filing integrating reactor coolant pump impellers inside the pressure vessel head. These active filings create significant freedom-to-operate considerations for any SMR developer adopting integral OTSG configurations.
United StatesWestinghouse Electric Company
Westinghouse Electric Co. LLC and Westinghouse Electric Corporation hold 4+ records across US, EP, and WO jurisdictions spanning 1994 to 2015. Key filings include two EP passive safety patents (1994 and 1997) addressing steam generator tube rupture via IRWST passive heat removal and steam line isolation, and a 2013/2015 compact steam generator with an external steam drum for decay heat removal. The passive SGTR mitigation design principles are now embedded in regulatory guidance, effectively constraining design space for new reactor developers.
United StatesFour Forward-Looking Directions in PWR Steam Generator Innovation (2022–2026)
Records published from 2022 onward reveal four distinct technology directions that represent the current frontier of PWR steam generator innovation, each driven by a different institutional and geographic cohort.
PWR Industrial Steam Cogeneration Surge (CN, 2022–2026)
The most active filing cluster involves multiple Chinese assignees independently developing architectures to supply 3–13 MPa industrial steam from large PWR units to replace coal boilers in chemical parks. Harbin Steam Turbine Factory Auxiliary Engineering Co., Ltd. filed the most recent record in this dataset (CN, January 2026), targeting clean low-carbon industrial steam supply to chemical, petrochemical, and pharmaceutical industries. SNERDI’s 2024 CN filing uses a heat pipe reactor to boost steam quality for industrial users.
PWR + HTGR Hybrid Steam Superheating (CN, 2023–2024)
Several 2023–2024 filings combine saturated-steam output of a PWR acting as a pre-heater with an HTGR superheater to raise steam parameters beyond what a standalone PWR can achieve. Xi’an Thermal Power Research Institute Co., Ltd. (CN, 2023) demonstrates three-stage heating — PWR to HTGR to reheat — to improve turbine thermal efficiency. China Nuclear Sueng Nuclear Power Co., Ltd. (CN, 2024) extends this architecture to enable simultaneous hydrogen production, power generation, and industrial steam co-production.
Recirculating Steam Generator vs. Once-Through Steam Generator: Key Design Dimensions
Click any row to explore further.
| Dimension | Recirculating Steam Generator (RSG) | Once-Through Steam Generator (OTSG) |
|---|---|---|
| Configuration | U-tube bundle, shell-and-tube with internal steam-water separators and dryers | Vertical or helical tube bundle, feedwater converted to steam in a single pass |
| Steam Output | Saturated steam at typically 6–7 MPa | Superheated steam; ACPR50 example: 4.68 MPa, 297.2°C |
| Primary Loop Integration | External large-loop piping connecting reactor vessel to SG vessel | Annular volume inside reactor pressure vessel; eliminates large primary loop piping |
| Loss-of-Coolant Accident Risk | Higher due to large primary loop piping connections | Reduced; integral design eliminates large-bore primary piping |
| Natural Circulation | Supported in classical designs; requires careful sizing of loop geometry | Fully passive natural circulation possible; used in BWXT mPower and CIAE miniature PWR |
| Thermal Inertia | Higher thermal inertia due to secondary water inventory in shell side | Lower thermal inertia; preferred for pulsed-plasma fusion regime (EU DEMO WCLL, ENEA 2023) |
| Key Assignees in Dataset | Kraftwerk Union AG, Siemens Aktiengesellschaft, AB Asea-Atom, Gidropress (VVER horizontal SG) | BWXT / Babcock & Wilcox, Westinghouse Electric Company LLC, CIAE, ENEA |
| Patent Status | Foundational patents broadly expired/inactive; mature technology | Active multi-jurisdiction families (BWXT 2012–2020); recent CN filings active |
Frequently Asked Questions: PWR Steam Generator Patents and Technology
Two dominant configurations appear: recirculating steam generators (RSGs) with U-tube bundles and internal steam-water separators, and once-through steam generators (OTSGs) that convert feedwater directly to superheated steam in a single pass. RSG designs are associated with foundational assignees such as Kraftwerk Union AG and Siemens Aktiengesellschaft, while OTSG designs are central to BWXT’s mPower integral PWR family and CIAE’s miniature PWR.
BWXT (formerly Babcock & Wilcox), through BWXT Foreign Holdings, LLC and BWXT mPower, Inc., holds 9+ records spanning US, CA, EP, and WO jurisdictions filed between 2012 and 2020 for the mPower compact integral PWR with an annular OTSG inside the pressure vessel. These active filings create significant freedom-to-operate considerations for any SMR developer adopting integral OTSG configurations.
Approximately 18–20 CN-jurisdiction records in this dataset were filed between 2019 and January 2026 by assignees including China Nuclear Power Engineering Co., Ltd., SNERDI, Jiangsu Nuclear Power Co., Ltd., Harbin Steam Turbine Factory Auxiliary Engineering Co., Ltd., and others. These filings address PWR secondary steam supply for industrial process heat — replacing coal boilers in chemical parks — reflecting China’s rapidly expanding nuclear fleet and decarbonization policy priorities.
SGTR is a design-basis accident where a breach in the primary-to-secondary boundary allows radioactive primary coolant to enter the secondary side. Westinghouse Electric filed patents in 1994 (US and EP) and 1997 (EP) covering passive mitigation: a passive heat removal heat exchanger immersed in an in-containment refueling water storage tank (IRWST) depressurizes the primary loop when triggered by high steam generator level, while core makeup tanks maintain coolant inventory and steam line isolation prevents flooding into steam headers.
ENEA, within the EUROfusion programme, published two 2023 literature records describing OTSGs for the EU DEMO WCLL fusion reactor. OTSGs are specifically selected because their lower thermal inertia better accommodates plasma pulsed regimes and dwell-period decay power levels compared to recirculating designs. The STEAM test facility at Brasimone is under construction to experimentally validate this approach, representing the first systematic extension of PWR-heritage OTSG technology to fusion applications.
Several 2023–2024 Chinese filings combine a PWR acting as a pre-heater producing saturated steam with an HTGR superheater that raises steam parameters beyond what a standalone PWR can achieve. Xi’an Thermal Power Research Institute Co., Ltd. (CN, 2023) demonstrates three-stage heating — PWR to HTGR to reheat — to improve turbine thermal efficiency. China Nuclear Sueng Nuclear Power Co., Ltd. (CN, 2024) extends this to simultaneous hydrogen production, power generation, and industrial steam co-production.
Data and insights on this page are based on a limited patent and literature dataset and are for reference only. Figures may not represent the complete technology landscape.