Secondary Steam Research Articles

Research on the radioactive safety of industrial steam supplied by PWR nuclear power plant

The heating source of the nuclear power steam supply installation is PWR secondary steam, but the secondary steam is potentially radioactive, and the radioactive material may migrate to the industrial steam, which goes through the leakage of the heat exchanger. Compared with the conventional industrial steam, the steam supplied by the nuclear power has potential radioactivity. Nuclear power is first introduced to produce the industrial steam, in order to analyze the specific activity and radiation effects of the industrial steam on the staffs at the user side, an analytical model of industrial steam radioactivity is developed based on the technological process of industrial steam under operating conditions, and then the exposure pathways of the staff at the user side from the industrial steam is analyzed. The specific activity of the industrial steam and the exposure dose of the staff is evaluated. According to the evaluation results, it can be seen that the dose to staff caused by the industrial steam is far smaller than the radiation impact on the public caused by the nuclear power plant, and can meet the requirements of relevant regulations and standards. Therefore from the radiation safety point of view, the industrial steam supplied by the nuclear power steam supply installation is safe and acceptable for industrial use.

Numerical analysis on the performance of sodium chloride solution evaporative crystallization system driven by high-temperature heat pump

In the context of sustainable development, heat pump technology is increasingly recognized as a key method for enhancing the efficiency of evaporative crystallization processes. In this study, we propose a high-temperature heat pump evaporative crystallization system to facilitate the recycling of waste heat from secondary steam in low-vacuum and low-temperature evaporative crystallization, thereby achieving the cyclic utilization of condensation heat from secondary steam. The primary objective of this research is to develop a comprehensive mathematical model for the HPC system that investigate its operating performance under varying conditions, with the aim of promoting its practical application. The results demonstrate that by adjusting operating pressures, the temperature of the secondary steam can be controlled, allowing for regulation of the main particle size of the product. Specially, when maintaining the flow rate of the raw material liquid at 90 % of design condition, it is possible to achieve a maximum main particle size of 2.8 mm. Additionally, fluctuations in the flow rate of the raw material liquid significantly impact the cycle rate, with the optimum operating flow rate range identified as 75 % to 110 % of the rated value. The coefficient of performance of the system can achieve 5.85 under design conditions with a concentration of 4 % and flow rate of 310 kg/h. This research provides a theoretical foundation for the practical operation and commissioning of the HPC units.

Thermal-hydraulic analysis of once-through steam generator with annular narrow slot tube

Integrated small modular reactors (SMR) have garnered significant attention in the field of nuclear energy, with the high-performance integrated steam generator being a critical technology for their advancement. The high-performance once-through steam generator (HP-OTSG) featuring an annular narrow slot tube, which leverages narrow channel enhanced heat transfer technology, holds significant potential for future applications. However, research on the design and experimental studies related to this type of steam generator remains significantly limited. This paper establishes a thermo-hydraulic analysis method for the OTSG based on the segmented heat exchanger design ideas, and the analysis method is verified by comparing the calculation results with those in the literatures. Then, the experimental studies conducted in the annular narrow slot tube and the related conclusions are comprehensively reviewed and subjected to an accurate assessment. The design parameters of a typical SMR, 200 MW Nuclear Heating Reactor-II (NHR200-II), are selected to evaluate and analyze the accuracy and validity of the correlation based on the annular narrow slot tube in the different heat transfer regions including the onset of nucleate boiling (ONB) point, saturated boiling heat transfer coefficient (hsat), dry-out point, and the post-dryout heat transfer coefficient (hpdo). Finally, the influences of operational and geometrical parameters on the performance of the HP-OTSG are analyzed, and the design optimization of the HP-OTSG is performed according to several performance indicators including Power Density (PD), Area Density (AD), pressure drop (Δp), secondary steam temperature (T2out), heat transfer factor (j), the proportion of nucleate boiling zone length in H (PNL), the point of dry-out (Xdryout), and the length of heat exchange tube (L). The model developed in this paper extends the application range of high-performance steam generators to annular narrow slot tubes. The calculation model including both of the analysis method and the heat transfer correlations established in the present study can serve as a useful tool for the design and optimization of HP-OTSG, which further prompts the development of integrated SMR with built-in steam generator.

Aspen plus-based techno-economic assessment of a solar-driven calcium looping CO2 capture system integrated with CaO sorbent reactivation

Given the gradual nature of the energy transition, retrofitting coal-fired power plants with carbon capture technology is crucial. The calcium looping (CaL) process is a promising solution, with challenges like absorbent deactivation and reduced thermal efficiency mitigated by absorbent reactivation and heat recovery systems. This study evaluated the techno-economic feasibility of integrating a novel wet extraction and precipitation process for absorbent reactivation within a solar-assisted CaL system, alongside an existing coal power plant. The process incorporated a secondary steam cycle and an ammonia absorption chiller for enhanced heat recovery and district cooling. The integrated project could increase daily power generation by 50% and reduce CO2 emissions from 820.4 g/kWh to 54.5 g/kWh. Over its lifespan, the reactivation facility could reduce limestone extraction by 21 Mt with 90% capture efficiency. With a levelized cost of electricity (LCOE) of 116.1 €/MWh and breakeven electricity selling price (BESP) of 56.6 €/MWh, the system demonstrated promising commercial viability, with the reactor and concentrated solar heating (CSH) system making up over 60% of investment costs. CSH cost and solar abundance were identified as key factors, indicating potential feasibility even in higher latitude regions. At CO2 revenues of 150 €/t, a stand-alone capture project can break even based solely on CO2 sales, demonstrating its potential for expansion to other areas. A case study highlighted the benefits of integrating absorbent reactivation and an ammonia absorption chiller, improving both economics and carbon capture efficiency. The study also confirmed the viability of solar-assisted projects in high-latitude regions, with optimistic future CO2 revenues and advancements in carbon capture technology enhancing feasibility.

Design of Major Components of Green Urea Production Plant

Green urea refers to urea produced using renewable energy sources such as municipal solid wastes (MSW) to create a more sustainable and eco-friendly approach to waste management and urea production. As the economy, population, and living standards proliferate swiftly, municipal solid waste has become a significant challenge, particularly in developing countries such as Nepal. This project aims to size the major components of a green urea plant that uses decomposable and combustible waste as feedstock. 15 CSTR digesters with a volume of 53323.2 m3 produced 41473.2 m3 of biogas to convert 740.6 Tons Per Day (TPD) of decomposable waste and 220.06 TPD of combustible waste into 574.4 TPD of green urea. A circulating fluidized bed gasifier, a Proton Exchange Membrane (PEM) electrolyzer, and an air separation unit using the cryogenic process were also selected. The study also involved picking a tubular steam methane reformer as the primary and an auto-thermal steam methane reformer as the secondary steam methane reformer. The shift reaction was carried out using a catalytic water gas shift reactor, and a three-bed type ammonia reactor was chosen for the Haber Bosch process. Finally, the Snamprogetti process was selected for urea synthesis. In addition, the study involves the preparation of a 2D system layout to understand the process flow and a 3D solid works drawing to visualize the plant design. The financial analysis of the green urea plant includes the calculation of CAPEX and OPEX, and it is found that total capital investment is 431.45 M$ and operating expenses are 102.2M$/year. Gasification, steam methane reformer, Air separation unit, ammonia synthesis, urea synthesis, electrolyzer, water gas shift reactor, and anaerobic digestion plant consist 7.15%, 13.55%, 3.32%, 16.13%, 26.12%, 13.37%, 13.43% and 6.93% of total capital investment respectively and 14.62%, 1.61%, 7.78%, 19.73%, 5.71%, 32.6%, 12.9% and 14.62% of total operating costs per year.

The Hybrid Concept of Turboshaft Engine Enhanced by Steam Cycle Using Waste Heat Recovery—Combined Analytical and Numerical Calculation of Its Efficiency

<div>The article presents a hybrid concept of a turboshaft engine that fits into the area of PGE (pressure-gained combustion). It combines the advantages and elements of a piston engine and a turbine engine. The combustion takes place in isochoric chambers. The proposed timing system of the engine efficiently realizes the Humphrey cycle. Additionally, the main gas cycle engine was enhanced by the Clausius–Rankine steam cycle to achieve effective power of engine equal to 1231.3 kW. It was supplied by waste heat recovery from the exhaust gas. The enhancement of the engine by the secondary steam cycle significantly improved engine effective efficiency with a final value reaching 0.446. The effective efficiency and specific fuel consumption of the engine were calculated using merged analytical–numerical CFD (computational fluid dynamics) analysis. The centrifugal compressor, gas turbine, and steam turbine can work on the common shaft whose rotational velocity is 35,000 rpm. Because of additional weight, it could have potential applications for stationary use or heavy military units.</div>

Loss model of low pressure compressor for mechanical vapor recompression system

Abstract Low pressure compressor (LPC) serves the role of enhancing pressure levels of secondary steam at nominal pressure ratios (1.5), procured from the evaporator as a primary thermal energy source. A loss model has been proficiently proposed to rapidly predict the performance of the LPC. Instead of conventional lump sum loss equations, the model adopts well-established one-dimensional (1D) loss formulations scattered across scholarly publications. Given an explicit configuration of the LPC, the environmental conditions, rotational velocity, and capacity, static and total temperatures, static and total pressures, pressure reductions, polytropic head, and efficiencies of each individual segment of the compressor can be calculated. Validation of this model was done using computational fluid dynamics (CFD) analysis. This model renders it feasible to conduct a parametric examination of the impact of each loss apparatus on the LPC’s capability, thereby aiding designers in substantiating design choices that minimize these losses and consequently positively influencing the comprehensive efficiency.

Rational Mode Parameters of Power Units Operating in Modern Energy Market Conditions

The paper analyzes the operation of condensing and heating turbines in modern energy market conditions with an assessment of the impact of operating parameters of live and secondary steam on economic indicators. It has been shown that when operating at variable loads, the most effective in terms of high-pressure turbines is a rational reduction in the initial pressure ps (sliding pressure), which leads to an increase in thermal efficiency by 1-1.5%. The experimental results of a study of the vacuum effect in the condenser on fuel consumption are presented in the paper as well. Using a specific example of the K-320-26.5 turbine unit, the need for a rational choice of cooling water flow in winter season to ensure optimal vacuum is shown. The issue of choosing a rational steam reheat temperature tr is examined in more detail. It has been established that one of the main reasons for the decrease in the efficiency of turbine units when operating in variable modes is the irrational use of the reheat temperature and the heat of phase transition in the flow part of the low pressure cylinder. The physical explanation of these processes in the turbine as tr decreases is given in detail. It has been shown that, as a result of analyzing the operation of turbine units of various capacities, a rational choice of reheat temperature (reducing tr by 10-20 °C) increases thermal efficiency by 1-2 %, and turbine efficiency - by 0.4-1.0 %. It is recommended to consider the pressure of the hot steam of the high pressure cylinder (рs), the pressure in the condenser (рc=f(tcirc.water)), as well as the reheating temperature tr, which altogether leads to a reduction in heat consumption by 2.5-3.5 % as rational parameters of steam when operating in variable modes. In order to increase the economic efficiency of the operation of turbine units of TPPs and CPPs at reduced loads, it is recommended to revise the regulatory documentation on the current amendments for changes in the reheat temperature. It is stated that with strict adherence to the recommendations discussed above, fuel savings at TTPs and CHPs in Ukraine can amount to 250–300 thousand tons of coal per year.

Problems and Countermeasures in the Implementation of STEAM Education in Middle Schools in the Internet Era

This paper mainly discusses the problems and countermeasures in the implementation of STEAM education in secondary schools in the Internet plus era. Based on the analysis of the current situation of STEAM education, this paper puts forward a series of countermeasures, including improving teachers quality, perfecting teaching facilities, innovating teaching methods and strengthening practical teaching. I hope this study can provide useful reference for promoting the healthy development of secondary school STEAM education.

Investigation of the inlet useful temperature difference effect on the distribution of hydrodynamic characteristics of the vapor-liquid flow inside the falling-film evaporator heating tube designed for a nitric acid solutions evaporation

We present the results of mathematical modeling of effect of inlet useful temperature difference on the vapor- liquid flow in the heat exchange tube of a vertical evaporating film apparatus, which is designed for evaporation of nitric acid solutions. Distributions obtained along the heat exchange tube length of local values of the: mass flow rate of the fluid and secondary steam, the velocity of the fluid film, the velocity of the secondary steam, the Reynolds criterion of the liquid and vapor phases, the absolute pressure depending on the values of this useful temperature difference. The study was carried out using numerical simulation. To study the effect of the initial useful temperature difference on the hydrodynamics of the vapor-liquid flow, the vertical evaporator equipped with the tube ø38x3 mm and length of L = 4 m was adopted. The linear nature of the distribution of hydrodynamic parameters along the length of the heat exchange tube is established. The absolute pressure in the tube space decreases along the heating tube due to pressure drop. The limiting factor in reducing the absolute pressure is the friction losses of the secondary vapor on the solution film surface. A decrease in the pressure in the tube space leads to decrease in the boiling point of the solution. This leads to increase useful temperature. This has a positive effect on the evaporation efficiency The obtained data should be used in the design of evaporation plants, which are designed for evaporation of nitric acid solutions.

Evaluation of STEAM Project-Based Learning (STEAM PBL) Instructional Designs from the STEM Practices Perspective

Currently, there is a wide diversity of project-based learning instructional designs presented as “STEAM projects”. However, it is essential to evaluate if all these STEAM projects align their learning objectives and activities with the intended STEAM competences. This paper aims to characterize the impact of the STEAM educational approach through the analysis of contemporary STEAM projects implemented in five Spanish secondary schools from a curricular perspective based on STEM practices. A dataset comprising 46 secondary school STEAM projects implemented in Spain was evaluated using STEM project-based learningrubric, considering 21 evaluation criteria. The findings reveal an imbalance in the sophistication of STEAM projects concerning Science and Technology disciplinary-linked criteria and meta-disciplinary-linked criteria within this framework. These results enable the mapping and highlighting of the fact that not all STEAM projects equally serve their intended educational purposes or integrate all their features with the same level of sophistication. Curriculum organizations from different secondary school levels are also pointing out notable differences regarding how they address STEM competence. Acknowledging these differences and challenges in further initiatives of STEAM PBL instructional designs could support their design. By identifying areas of improvement, educators can optimize the impact of these projects on fostering STEAM competences among students.

System-level modeling, analysis and coordinated control design for the pressurized water reactor nuclear power system

A flexible operation of the nuclear power system (NPS) over a large operating range is emphasized when it is used as marine power. The current study exposes two bottlenecks in this field: (1) lack of the system-level high-quality dynamic model whose structure is simple enough for control design limits the implementation of the model-based controller; (2) nonlinearity problem due to the large load variation poses challenges for NPS to maintain its performance over a wide operating range. For these reasons, a first-hand simplified nonlinear model is developed and validated for the pressurized water reactor nuclear power system (PWRNPS) through mixed modeling methods of mechanism analysis and data identification. An optimal 50% full-power compromise steady-state operation scheme is first proposed for PWRNPS to balance its primary coolant temperature and secondary steam pressure. Using the simplified nonlinear model as the predictive model, a novel nonlinear model predictive controller (NMPC) is designed to realize the wide-range flexible operation of PWRNPS. Especially, an integrating tracking error is innovatively added to the cost function of NMPC to achieve offset-free control. Two groups of simulations on a complex PWRNPS process developed on the MATLAB/SIMULINK platform demonstrate the effectiveness of the proposed methods.

Numerical Study on Flow and Noise Characteristics of High-Temperature and High-Pressure Steam Ejector

Based on the shear stress transfer (SST) k-ω model, Ffowcs-Williams and Hawkings (FW–H) equation, and Lilley sound source equation, the flow and sound field of high-temperature and high-pressure steam ejectors are simulated. The entrainment performance, near-field sound source, and far-field noise of the steam ejector are discussed. The influences of working parameters including the primary steam pressure, the secondary steam pressure, and the back pressure are analyzed. The results show that under the design conditions, the steam ejector has two shock waves and three sound source regions. A shear layer at the boundary of the first shock wave generates the Sound source-I, and the flow separation at the boundary of the second shock wave causes the Sound source-III. The Sound source-II is located near the mixing chamber wall and the sound pressure levels around the ejector depend on the distances from the Sound source-II. In terms of the entrainment performance, with the increasing primary pressure or the decreasing secondary pressure, as the driving pressure difference of the secondary steam decreases, so does the entrainment ratio. As the back pressure increases, the entrainment ratio firstly remains constant, and then rapidly decreases when the back pressure exceeds the critical value at pb = 5.5 MPa. In terms of the noise characteristics, the sound pressure level and the intensity of the second shock wave have a positive correlation. When the primary or secondary pressure increases, the sound pressure level increases. Moreover, with the increasing back pressure, the sound pressure level firstly decreases, reaches the minimum of 98.2 dB at the critical back pressure, and then slowly increases.

Study of the features of modeling microwave vacuum evaporation

Evaporation is the most common concentration method. The complete reuse of latent thermal energy by means of mechanical recompression is the most technologically efficient method of operation of evaporators. This method requires much less electricity to compress the secondary steam compared to the heat of the secondary steam. In this scheme, the energy released during steam condensation can be used to heat the initial solution, which makes it possible to achieve the reuse of thermal energy at the level of 95%. Thus, during the the evaporation process implementation, when energy is supplied by electromagnetic microwave radiation, conditions are created for the initiation of vaporization in the entire liquid volume, which will avoid product overheating in the thermal boundary layer due to the absence of such. This allows to get a product of high concentration, without the taste of “cooking”, without changing color and flavor. When modeling these processes, boundary conditions of the third kind are replaced by boundary conditions of the second kind. Considering the proposed hypothesis, a process model can be considered, assuming the presence of internal energy sources evenly distributed in the product volume. This opens up the possibility of using deterministic mathematical models, provided that the corresponding initial and boundary conditions are determined. As a result of generalization of the experimental modeling results, a model in a criterion form has been obtained, which allows calculating a microwave vacuum-evaporation apparatus of periodic action for solutions containing polar molecules. The model in the range of dimensionless pressure 2 ≤ P ≤ 22, and at the level of dimensionless heat of the phase transition 1 ≤ R ≤ 4.56 provides accuracy with a maximum deviation of ± 8%.

Comprehending the Effect of Nature-Based Community-Based Service Learning on Students' Engagement, Community Involvement, Servant Leadership in Secondary and Higher STEAM Education

Comprehending the Effect of Nature-Based Community-Based Service Learning on Students' Engagement, Community Involvement, Servant Leadership in Secondary and Higher STEAM Education

Energy-efficient vacuum evaporation units for concentration in the dairy industry

The application of various types of evaporation plants for concentration of solutions was analyzed. It was noted that the most promising for thickening dairy products are film-type vacuum-evaporation units with mechanical compression of secondary steam. The heating chamber of the evaporator is made in the form of a vertical shell-and-tube heat exchanger with the supply of heating steam into the intertube space and with the downward movement of product solutions in the vertical boiling tubes. Based on the analysis of known studies on hydrodynamics and heat exchange of film processes (condensation, film heating and evaporation and steam separation), a conclusion was made about the lack of data for calculating pressure losses in the steam circuit of the evaporator with sufficient accuracy. To solve this problem, improved methods of calculating the hydraulic resistance of the intertube steam path of the heating chamber and the two-phase flow of the product film and secondary steam in evaporative boiling tubes have been developed using the published results of hydrodynamic resistance research. Pressure losses for the movement of secondary steam in the lower chamber of the evaporator include losses for acceleration of the steam released from the falling film of the product. It is shown that the hydraulic depression of the movement of steam in the intertube space of the heating chamber, depending on the type of scheme, can be from 2.3% to 77% compared to the working temperature pressure of the heating surfaces. The four-way flow scheme of the heating steam used in the design of the vacuum-evaporation unit ensures a reduction of hydraulic losses by up to 15%. A technical and economic analysis of the costs of operating a vacuum-evaporation unit with a productivity of 10 t/h of vaporized steam was performed, according to which the lowest reduced costs were established at a temperature drop of 5˚C on the compressor. The results of the research were used in the development of structures and the manufacture of vacuum-evaporation units with mechanical and mixed (mechanical and thermal) compression at PrJSC "Kalyniv Machine-Building Plant" (Kalynivka, Vinnytsia Region). 10 vacuum evaporation units with a capacity of 5 to 20 t/h of evaporated moisture were manufactured and put into operation.

Steady-state thermal hydraulic modelling and turbine trip transient simulation of the NuScale integral pressurised water reactor using the ASTEC code

A steady state model of the NuScale reactor has been built using the thermal hydraulic module CESAR of the severe accident code ASTEC. Construction of the model was achieved through iterations based on convergence towards data provided by NuScale pertaining to important operating properties—core temperatures, coolant mass flow rate and secondary steam temperature—at 100% power (160 MW) and also at lower power levels. Good agreement with reference values was achieved to within 3% deviation. With a similar methodology, the previous model was adjusted to give a second steady state model meant to provide conservative initial conditions from which a turbine trip transient simulation would be performed. Sound agreement with literature was achieved, with maximum deviations of less than 1.8% for monitored parameters. Lastly, a turbine trip transient was simulated and compared to reference data from analyses performed with NRELAP5 and RELAP5/SCDAPSIM. The most important system behaviors and event timings are well captured and reproduced, with discrepancies arising from inevitable estimates made due to lack of information.

중등 STEAM 연구 동향 분석

Objectives This study analyzed the trends of Korean research on secondary school STEAM learning targeting master’s and doctoral dissertations released for the last 10 years from 2012 to 2021 in order to present foundational material that can help study STEAM and conduct related education afterwards. Methods By using the database of KERIS, this author selected 176 master’s and doctoral dissertations related to STEAM and analyzed the trends of research in terms of study characteristics, topics, subjects, and methods. Concerning the study method, this research conducted frequency analysis and crossover analysis using Excel as part of literature review. Results First, according to the results of analyzing the characteristics of theses, regarding the years of publication, a lot of research was done from 2013 to 2019 as 145 theses (82.4%). Concerning universities releasing them, more theses were released by ‘Korea National University of Education’, ‘Yonsei University’, ‘Kongju National University’, and ‘Ewha Womans University’ in order. About degrees, 165 were ‘master’s theses’, and 11 were ‘doctoral dissertations’. Second, regarding the topics of research, 47 were about ‘development’, 36 were for ‘development and application’, 29 were about ‘influences and effects’, and 26 dealt with ‘analysis’, and so on. Third, about the subjects of research, 82 theses targeted ‘literatures’, 46 ‘middle school students’, and 34 ‘high school students’, and so on. Fourth, concerning study methods, 83 were ‘studies reviewing literatures’ and 79 were ‘quantitative research’. Conclusions Based on the above results of analyzing the major trends, this author concludes that research on secondary school STEAM learning deals with such topics as ‘development’ and ‘development and application’, targets literatures or middle/high school students, and adopts study methods like literature review or quantitative research. Follow-up research will have to be done systematically in a way to excavate diverse topics about secondary school STEAM learning and diversity the subjects and methods further.

Preheating of secondary superheated steam pipelines when starting steam turbines of SCР power units

Specific features of the technology of preheating hot legs of steam pipelines of intermediate steam overheating at the start-up of SCР power units with single-bypass thermal circuits are presented, with the advantages and disadvantages of various previously used methods of preheating steam pipelines after intermediate steam overheating at the startup of power units at supercritical pressure with a capacity of 250–300 MW considered. The analysis of the conditions for the completion of the heating of these steam pipelines using various process heating arrangements, as well as the heating steam consumption necessary for heating and its sources (special kindling steam by-passes, steam by-passes of own needs, kindling expander and combined heating technology at various intermediate rotational speeds of the turbine rotor) is carried out. The results of computational and experimental studies of the heating processes of steam pipelines during the start-up of SCР power units from various thermal states are presented, nomograms for determining the duration of preheating of mono and double steam pipelines with a capacity of 250–300 MW, developed on the basis of solving the inverse problem of thermal conductivity, are presented. The basis for determining the duration of heating of steam pipelines is the assumption of limited cooling of the medium pressure rotor of the steam turbine as steam is supplied to the same, as well as the temperature of the end section of the steam pipeline, which excludes the formation of condensate and thereby reduces the risk of its removal into the flow part when steam is supplied to the medium pressure cylinder. Two criteria for the termination of heating are determined in the form of an average integral temperature of the middle part of the steam pipeline and the temperature of its end section upstream the steam inlet elements of the medium pressure part.

Thermo-economic assessment of flexible nuclear power plants in future low-carbon electricity systems: Role of thermal energy storage

The increasing penetration of intermittent renewable power will require additional flexibility from conventional plants, in order to follow the fluctuating renewable output while guaranteeing security of energy supply. In this context, coupling nuclear reactors with thermal energy storage could ensure a more continuous and efficient operation of nuclear power plants, while at other times allowing their operation to become more flexible and cost-effective. This study proposes options for upgrading a 1610-MWel nuclear power plant with the addition of a thermal energy storage system and secondary power generators. The total whole-system benefits of operating the proposed configuration are quantified for several scenarios in the context of the UK’s national electricity system using a whole-system model that minimises the total system costs. The proposed configuration allows the plant to generate up to 2130MWel during peak load, representing an increase of 32% in nominal rated power. This 520MWel of additional power is generated by secondary steam Rankine cycle systems (i.e., with optimised cycle thermal efficiencies of 24% and 30%) and by utilising thermal energy storage tanks with a total heat storage capacity of 1950MWhth. Replacing conventional with flexible nuclear power plants is found to generate whole-system cost savings between £24.3m/yr and £88.9m/yr, with the highest benefit achieved when stored heat is fully discharged in 0.5 h. At an estimated cost of added flexibility of £42.7m/yr, the proposed flexibility upgrades to such nuclear power plants appears to be economically justified with net system benefits ranging from £4.0m/yr to £31.6m/yr for the examined low-carbon scenarios, provided that the number of flexible nuclear plants in the system is small. This suggests that the value of this technology is system dependent, and that system characteristics should be adequately considered when evaluating the benefits of different flexible nuclear plant configurations and choosing the most cost-effective designs and operational characteristics.