Core Heat Research Articles

Numerical study on the flow and heat transfer characteristics in a high-temperature gas-cooled reactor core

In the high-temperature gas-cooled reactor (HTGR), the core operation heavily relies on the heat transfer process facilitated by the coolant that withdraws the heat released by fuel particles. Therefore, it is imperative to carefully study the flow and heat transfer characteristics between the fuel particle and coolant. Additionally, under high core temperature conditions, the fuel particle tends to incur damage. In this study, we have designed a new type of HTGR using hydrogen as a coolant, and performed numerical simulations to explore the flow and heat transfer conditions in the core under various working conditions. Our results indicate that under high velocity inlet and low temperature inlet conditions, the system provides a high heat transfer rate. Furthermore, interesting relationships were observed between the flow and heat transfer characteristics of the model through the Reynolds number (Re), n, and Tr. Since the density of the coolant changes as the temperature varies, the hydrogen is susceptible to compression. Notably, poor thermal conductivity on the fuel particle surface generates hotspots at the points of flow stagnation, flow separation, and flow convergence. Our study on the new reactor core's flow and heat transfer characteristics provides an important reference for improving the core outlet temperature and the fuel particle's structure.

A coupled analysis on human thermal comfort and the indoor non-uniform thermal environment through human exergy and CFD model

The importance of human thermal comfort evaluation lies of the development of healthy buildings as well as low-carbon buildings. In recent years, the applications of the second law of thermodynamics to thermal comfort offered a new perspective and this study, for the first time, an integrated human exergy model and the indoor CFD model for a coupled analysis is put forward, which supplements a critical link between human and building environment. In this paper, a predefined office model is investigated to improve the efficiency and thermal comfort of occupants. Based on the human exergy model, the parameters of metabolism, respiration, evaporation, convection, radiation, skin, and core heat storage terms are optimized. Additionally, the effects of gender, age, and clothing thermal resistance on the exergy model values are also separately explored. Finally, the optimized human exergy model is combined with computational fluid dynamics (CFD) to calculate, under different air supply conditions, the distribution of exergy consumption values in the predefined room model. The results show that the factors of gender, age, and thermal resistance of clothing have some influences on human exergy consumption, while the above factors do not have a significant enough influence on the model in the thermal comfort interval. Moreover, the combination of the human exergy model and CFD can offer some suitable air supply conditions for the development of indoor thermal comfort and work efficiency. This study presented a new tool that bridges human thermal sensation and indoor thermal environment.

Genetic inactivation of essential HSF1 reveals an isolated transcriptional stress response selectively induced by protein misfolding.

Heat Shock Factor 1 (Hsf1) in yeast drives the basal transcription of key proteostasis factors and its activity is induced as part of the core heat shock response. Exploring Hsf1 specific functions has been challenging due to the essential nature of the HSF1 gene and the extensive overlap of target promoters with environmental stress response (ESR) transcription factors Msn2 and Msn4 (Msn2/4). In this study, we constructed a viable hsf1∆ strain by replacing the HSF1 open reading frame with genes that constitutively express Hsp40, Hsp70, and Hsp90 from Hsf1-independent promoters. Phenotypic analysis showed that the hsf1∆ strain grows slowly, is sensitive to heat as well as protein misfolding and accumulates protein aggregates. Transcriptome analysis revealed that the transcriptional response to protein misfolding induced by azetidine-2-carboxylic acid is fully dependent on Hsf1. In contrast, the hsf1∆ strain responded to heat shock through the ESR. Following HS, Hsf1 and Msn2/4 showed functional compensatory induction with stronger activation of the remaining stress pathway when the other branch was inactivated. Thus, we provide a long-overdue genetic test of the function of Hsf1 in yeast using the novel hsf1∆ construct. Our data highlight that the accumulation of misfolded proteins is uniquely sensed by Hsf1-Hsp70 chaperone titration inducing a highly selective transcriptional stress response.

Experimental study on top liquid-cooling thermal management system based on Z-shaped micro heat pipe array

The traditional bottom liquid-cooling thermal management system (TMS) has poor cooling performance and is prone to causing significant temperature difference in the lithium-ion battery (LIB) module. In order to solve the above problems, this study takes the Z-shaped micro heat pipe array (MHPA) as the core heat transfer element and establishes a top liquid-cooling (TLC) TMS based on Z-shaped MHPA. The thermal management performance of the TLC TMS based on Z-shaped MHPA is analyzed by comparing it with the traditional bottom liquid-cooling TMS. Results show that under the conditions of 40 °C ambient temperature and 25 °C cold water inlet temperature, the bottom liquid-cooling TMS can no longer meet the thermal management requirements of the module at a 2C charge–discharge rate. In comparison, the TLC TMS based on Z-shaped MHPA can ensure the module's maximum temperature below 55 °C, and the battery and module level's temperature difference can be controlled below 4 °C under 3C charge–discharge rate. The TLC TMS based on Z-shaped MHPA can not only effectively delay the battery's temperature rise under high charge–discharge rate, but also significantly reduce the temperature difference; its thermal management performance is significantly better than the bottom liquid-cooling TMS.

Thermohydraulic characteristics of water–cooling oil heat exchanger with vortex generators and its enhanced heat transfer mechanism

In this paper, thermohydraulic characteristics and enhanced heat transfer mechanism in water–cooling oil heat exchanger with various shapes and attack angles of vortex generators (VGs) and spacing of double VGs are numerically investigated at different Reynolds number (Re) and oil–water mediums. A CFD-aided method, conjugated heat transfer model, is performed to elaborate the correlation between heat transfer and flow characteristics. The quantitative and qualitative results manifest that the longitudinal and secondary vortices, induced by VGs, generate synergistically the tapered and elliptical enhanced heat transfer regions on the heat exchange fins, but the inhibiting effect still exists between both, particularly in high attack angle or oil medium. Elliptical winglet VG with 30° in oil medium with Re = 349 and 15° in water medium with Re = 2726 gains the maximum thermal performance factor, reaching 1.69 and 1.28, respectively, compared without VGs. Furthermore, the appropriate configuration of two core heat transfer regions is a cost-optimal method to obtain in-depth synergistic heat transfer. The spacing of 4 mm shows the best synergistic heat transfer, and the maximum heat flux of its was elevated to 2.2% and 8.6% more than that of single VG in oil and water medium, respectively.

Dynamics Model Construction and Characteristic Analysis of Heat Pipe Nuclear Reactor in Thermal State

In order to facilitate the power control method design of heat pipe nuclear reactor and avoid the high complexity of reactor core modelling, the paper adopts the lumped parameter method to build the thermal state dynamic model of heat pipe reactor. Firstly, the equivalence of the core structure and heat transfer process of the “MegaPower” heat pipe nuclear reactor is carried out to describe a single heat pipe in a hexagonal block. The complex heat transfer process in reactor core is simplified into a two-zone heat transfer model with only fuel and monolith. And the equivalent thermal resistance is used to describe the heat conduction process within gas gap and heat pipe. Then, the reactor core nuclear dynamic model is established using the neutron dynamics equation of point-reactor. Based on the principle of heat balance, the thermal dynamics models of fuel, gas gap, monolith and heat pipe are established respectively, so as to form the state equations of heat generation and heat transfer process in reactor core. Finally, the dynamic characteristics of the reactor with the reactivity disturbance without external control are simulated and analysed. The results show that the heat pipe reactor has a certain self-stability with reactivity disturbance, but the stability time is long, and the power fluctuation is large.

Linking the Core Heat Content to Earth's Accretion History

AbstractIn this study we use a parameterized model of differentiation in a magma ocean setting, in which the magma ocean depth evolves during accretion, to predict the composition of the primordial core. We couple this chemical model to a thermal evolution model of the accreting metal to estimate the Earth's core heat content at the end of its formation. We find geochemically consistent models. All these scenarios have in common two key features: (a) the average pressure of metal‐silicates equilibration is between 20 and 45 GPa (final pressure between 40% and 60% of CMB pressure); (b) 60%–80% of Earth's mass is accreted as reduced material. The chemical stratification is stable in most cases, though some scenarios result in an unstable compositional stratification. Mixing an initially stratified core requires a small fraction of the energy released after a giant impact. Importantly, the temperature at the Core Mantle Boundary is ranging from 3925 to 4150 K. For example, scenarios in which the magma ocean remains shallow for a large part of the accretion, then gets deeper at the end of accretion can produce chemically coherent models with cooler cores. This suggests that independent constraints on the core temperature could in principle be used as constraints for the differentiation conditions, and core composition. In particular, we find that the abundance of light elements in the core correlates positively with the temperature of the core at the end of accretion, as well as with the average pressure of equilibration during differentiation.

Thermal-hydraulic analysis of He–Xe gas mixture in 2×2 rod bundle wrapped with helical wires

Gas-cooled space reactor, which adopts He–Xe gas mixture as working fluid, is a better choice for megawatt power generation. In this paper, thermal-hydraulic characteristics of He–Xe gas mixture in 2 × 2 rod bundle wrapped with helical wires is numerically investigated. The velocity, pressure and temperature distribution of the coolant are obtained and analyzed. The results show that the existence of helical wires forms the vortexes and changes the velocity and temperature distribution. Hot spots are found at the contact corners between helical wires and fuel rods. The highest temperature of the hot spots reach 1600K, while the mainstream temperature is less than 400K. The helical wire structure increases the friction pressure drop by 20%–50%. The effect extent varies with the pitch and the number of helical wires. The helical wire structure leads to the reduction of Nusselt number. Comparing thermal-hydraulic performance ratios (THPR) of different structures, the THPR values are all less than 1. It means that gas-cooled space reactor adopting helical wires could not strengthen the core heat removal performance. This work provides the thermal-hydraulic design basis for He–Xe gas cooled space nuclear reactor.

Forced-air prewarming prevents hypothermia during living donor liver transplantation: a randomized controlled trial

Despite various intraoperative thermal strategies, core heat loss is considerable during liver transplantation and hypothermia is common. We tested whether forced-air prewarming prevents hypothermia during liver transplantation. Adult patients undergoing living donor liver transplantation were randomly assigned to non-prewarming group (n = 20) or prewarming group (n = 20). Patients in prewarming group underwent 30-min forced-air warming before anesthetic induction. During surgery, core temperature was measured in the pulmonary artery. The primary outcome was intraoperative hypothermia (< 36.0 °C). The secondary outcomes included plasma lactate concentration. Intraoperative hypothermia risk was significantly lower in prewarming group than in non-prewarming group (60.0% vs. 95.0%, P = 0.020). The difference in hypothermia incidence between groups was greater in the post-induction phase (20.0% vs. 85.0%, P < 0.001) than in the anhepatic or post-reperfusion phase, suggesting that prewarming mainly acts on preventing post-induction core-to-peripheral heat redistribution. Hypothermia duration was significantly shorter in prewarming group (60 [0–221] min vs. 383 [108–426] min, P = 0.001). Lactate concentration decreased during 3 h after graft reperfusion in prewarming group, whereas it continuously increased in non-prewarming group (− 0.19 [− 0.48 to 0.13] mmol/L vs. 1.17 [3.31–0.77] mmol/L, P = 0.034). In conclusion, forced-air prewarming decreases the incidence and duration of intraoperative hypothermia with potential clinical benefit while mainly acting by preventing the core-to-peripheral heat redistribution.Clinical trial registration: Registered at the Clinical Research Information Service (https://cris.nih.go.kr, [KCT0003230]) on 01/10/2018.

Numerical Analysis of Liquid Potassium Flow and Heat Transfer in a Core for Space Nuclear Reactor Based on Entransy Dissipation Theory

AbstractThe research on the flow and heat transfer of alkali metals is an important technical means to strengthen the heat transfer of the core. In this paper, the 15 cooling channels with different structures are established. Under Re = 2.85 × 104–2.17 × 105, several operating parameters, such as core inlet temperature (T = 350 K, 390 K, 450 K, 550 K, 850 K), fuel rod pitch ratio (P = 1.2, 1.4, 1.6, 1.8, 2.0), and channel shape (triangle and square) on the heat transfer performance are numerically simulated. At the same time, this work introduces an evaluation criterion, entransy dissipation, to measure the irreversibility of the heat transfer process. The results show that the triangular channel has a stronger heat transfer capacity than the square. And the increase of the rod diameter ratio is a positive means to enhance the heat transfer. Among the studied channels, Model “I” (triangle channel, P = 2.0) has the best heat transfer performance. The above results have some guiding value to realize core heat transfer enhancement by adjusting fuel rod arrangement.

New Approach for the Root Cause of Fukushima Meltdown Accident

The purpose of this Commentary is to clarify as much as possible the whole history of reactor and containment pressure changes in the Fukushima meltdown accident. It is based on a new approach for film boiling, which is kept after the Zr-H₂O reactions. Most important point of this approach is that the author applied film boiling based on boiling curve, which is basic theory in boiling phenomena, for the Fukushima accident phenomena. As the reaction rate is proportional to the reactor or containment pressure under film boiling, it increases rapidly and stops suddenly, keeping the film boiling. The containment pressure change consists of three phases, namely pressurizing, keeping the high pressure and de-pressurizing. The containment is pressurized by H₂ gas and steam produced by the Zr-H₂O reactions and de-pressurized by a heatsink such as the containment wall and inner shield concrete after reaction stops. The high pressure between these pressure changes is kept by balancing the H₂ gas produced by reaction with the leaked gas from the gap between the top lid and the containment. Core decay heat is large, but its change is negligibly small. So, the pressurization is calculated from H₂ gas and steam produced by the Zr- H₂O reactions. The heatsink balances with the reaction during the high pressure condition. The de-pressurization occurs after the reaction is over, so the reaction heat rate can be calculated by the heat rate of the heatsink, which is equal to the condensation rate during de-pressurization. The leak rate of the leak gas can be calculated using the reaction rate. It is very important that the rection rate is slowed by the insufficient steam supply, as the melted reactor cores in the Fukushima accident were covered with H₂ gas and steam (film boiling) at 0.8MPa or lower pressure. This is different from the rate (at approx. 7MPa) in the Three Mile Island accident, as the steam specific volume at 0.8 MPa is ten times larger than that at 7 MPa. The calculation results based on this assumption show that almost all the Zr in each core of Units 1, 2 and 3 reacted with water.

Exploring the Predictive Potential of Physiological Measures of Human Thermal Strain in Outdoor Environments in Hot and Humid Areas in Summer-A Case Study of Shanghai, China.

Whenever people spend time outdoors during hot weather, they are putting themselves in potentially stressful situations. Being able to predict whether a person is overheating can be critical in preventing heat-health issues. There is a clear relationship between body core temperature and heat health. However, measuring body core temperature is expensive. Identifying a non-invasive measure that could indicate a person's thermal strain would be valuable. This study investigated five physiological measures as possible surrogates: finger mean skin temperature (FSKT), finger maximum skin temperature (FMSKT), skin conductance level (SCL), heart rate (HR), and heart rate variability (HRV). Furthermore, they were compared against the results of participants' subjective thermal sensation and thermal comfort in a range of hot microclimatic conditions in a hot and humid climate. Results showed that except for SCL, each of the other four physiological measures had a positive significant relationship with thermal sensation, but a negative relationship with thermal comfort. Furthermore, through testing by cumulative link mixed models, HRV was found to be the most suitable surrogate for predicting thermal sensation and thermal comfort through a simple, non-invasive measure in outdoor environment in summer in a hot and humid area. This study highlights the method for predicting human thermal strain and contributes to improve the public health and well-being of urban dwellers in outdoor environments.

Desain Dan Implementasi Transformator Satu-Fasa Dry-Type Dengan Pendekatan Core Geometry

Energy is one of the most important needs for humans to support daily life, especially for developing countries such as Indonesia. One of the energies needed in human life is electrical energy. For this reason, innovation was developed, namely a dry-type Single-Phase Transformer with a core geometry approach developed in the AL 1.01 building of the State Polytechnic of Malang. Calculations performed on the tool are to calculate the value of windings per volt (GPV) and the number of primary and secondary windings. Its manufacture uses a toroid-shaped transformer core. The core specification of the transformer is an outer diameter of 15cm, then an inner diameter of 5.8 cm, and a height of 7cm. The toroid transformer core that will be used is previously isolated from the transformer first to avoid leakage current which can cause heat in the transformer core. The density of the email wire from the transformer winding both from the primary and secondary windings will affect the performance of the transformer, the more tightly the email Wire is wrapped in the transformer core, the vibration generated from the transformer will be smaller, this will affect the voltage losses later in the transformer testing phase carried out using different beaban, each load changes the efficiency of the transformer that has been made will also change, this is because each load tested has different factors.

Multi-physics coupled simulation on steady-state and transients of heat pipe cooled reactor system

With superior inherent safety and low maintenance demand, heat pipe cooled micro-reactor is a potential solution for decentralized remote electricity supply, as well as space power technology. Multi-physics coupled analysis is important to evaluate the inherent safety feature of micro-reactor. However, in the existing multi-physics coupling simulations, lumped parameter core heat transfer model and low-fidelity heat pipe model cannot accurately predict steady-state and transient safety margin of the reactor. In order to improve the simulation accuracy, a standalone two-dimensional transient high-temperature heat pipe analysis code was developed and validated. The heat pipe analysis code was coupled with the three-dimensional thermal conduction calculation of reactor core, as well as the point reactor kinetics, the alkali metal thermal-to-electric converter model and the heat pipe radiator model, to realize fully coupled analysis of reactor system. With the power distribution in the reactor core, the steady state, startup transient and single heat pipe failure accident were simulated based on the multi-physics coupling. The steady-state simulation results show that the heat flux of heat pipes shows significant non-uniformity in both circumferential and axial directions. The peak heat flux (120 kW/m2), with the twice value of averaged one (60 kW/m2), occurs on the heat pipes near the reactor edge rather than in the center. During reactor startup, the reactivity-insertion rate of 1.67e-3 $/s increases the transient peak heat flux to 260 kW/m2. The isothermal feature of heat pipes results in inverse heat transfer, i.e. from heat pipes to reactor structure, which improves the axial and radial reactor heat transfer and flattens the reactor temperature distribution. In the central heat pipe failure accident, more severe local temperature rise was observed in the core structure than that in the fuel pins. The peak heat flux location is shifted to the heat pipes adjacent to the failed heat pipe. Benefitted from the developed high-fidelity multi-physics coupling approach, the realistic transient phenomena in heat pipe cooled micro-reactor could be revealed.

Influence of guide tubes on configuration and heat-up behaviour for PHWR specific suspended debris bed – An analytical assessment

The estimation of accident source term and hydrogen generation is dependent on the core heat-up under postulated accident scenarios. The uncertainty of such estimations increases as the accident severity increases due to complexity in the determination of i) evolving degraded core configurations, and ii) associated suitable physical models for heat-up and degradation simulation. Analysis of postulated severe accidents for PHWR is essential for emergency planning and severe accident management guidelines from a plant licensing perspective. The study presents the order of uncertainty that is present as of today in deciding the size and shape of the suspended debris bed, which in turn decides the exposed core heat up, hydrogen generation as well as fission product release. The study reveals that the location and integrity of reactivity mechanism guide tubes significantly impact the exposed core heat-up, channel disassembly pattern and shape and size of the suspended debris bed. Nevertheless, the experimental study on the guide tube behaviour on asymmetric heat-up condition and their failure will further substantiate the postulation of suspended debris bed configuration.

Experimental investigation on thermal performance of solar water heater equipped with Serpentine fin core heat exchanger

Experimental investigation on thermal performance of solar water heater equipped with Serpentine fin core heat exchanger

Engineering of the Core-Shell Boron Nitride@Nitrogen-Doped Carbon Heterogeneous Interface for Efficient Heat Dissipation and Electromagnetic Wave Absorption.

The effective integration of multiple functions into electromagnetic wave-absorbing (EWA) materials is the future development direction but remains a huge challenge. A rational selection of components and the design of structures can make the material have excellent EWA performance and heat dissipation. Herein, the core-shell structured boron nitride@nitrogen-doped carbon (BN@NC) is prepared by using waterborne polyurethane (WPU) as the carbon source via a facile pyrolysis treatment process, where NC is used as the conductive loss shell, and BN serves as an impedance matching core and dominant heat transfer media. As a result, the BN@NC-900 filled with paraffin wax yields a minimum reflection loss of -42.2 dB at 2.2 mm and an effective absorbing bandwidth of 4.48 GHz at 1.8 mm, and its thermal conductivity reaches up to 0.92 W/m·K in epoxy resin. Most importantly, flexible BN@NC/WPU films are prepared and simultaneously achieve the dual-functional capability of efficiently dissipating heat and electromagnetic waves (-50.0 dB). Besides, an attractive multiband absorption feature (>99%) from C to Ku bands is realized and a strong absorbing over -27.0 dB at the S band (2.88 GHz) is even achieved. This study may pave a new route for the rational design of multifunctional EWA materials.

Coregistered positron emission particle tracking (PEPT) and X-ray computed tomography (CT) for engineering flow measurements

Increasingly, fully 3D experimental measurements of flow in complex engineering geometries are required to validate computational fluid dynamics models that support and inform reactor design and licensing. One barrier to such measurements is the complexity of typical reactor components and subsequent lack of optical access in these systems. To overcome this, the deployment of coregistered positron emission particle tracking (PEPT) and X-ray computed tomography (CT) is explored for flow measurement in reactor thermal hydraulic components and model (scaled) systems. Through this methodology, fully 3D flow information (via PEPT) and detailed internal geometry (via CT) are captured in opaque systems such as pipes, rod bundles, packed beds, etc. The reconstructed flow field and geometry can then be overlain to reveal detailed flow features around internal structures within a given test section. This is enabled through the use of a combined preclinical PET/CT scanner with overlapping PET and CT fields of view. Such measurements are useful for characterizing flow inside such intricate nuclear thermal hydraulic components as core geometries and heat exchangers, among others, and providing valuable 3D validation data for CFD models. In this work, basic tests of this 3D flow/geometry mapping are presented, and the implications of such measurements are discussed. Preliminary measurements are made with both point sources and flow in a simple pipe flow geometry to evaluate the capabilities of this technique. PEPT and CT features are coregistered with up to 0.1 mm precision, and pipe flow mean velocity and Reynolds stresses are reconstructed with similar accuracy to previous PEPT demonstrations. The utility of PEPT/CT is shown herein, and suggestions for future measurements are made.

Generation of all-fiber third-order orbital angular momentum modes based on femtosecond laser processing of long-period grating

The generation of orbital angular momentum (OAM) modes is very important, for they have a variety of applications such as in optical tweezers, quantum optics, and optical communication systems. Particularly, how can high-order OAM modes be generated efficiently in fibers with the advantage of low cost and compatible with fiber system? The Traditional method for first order to third order OAM is based on long period fiber grating (LPFG) fabricated by carbon dioxide laser. However, high power and large focused spot of carbon dioxide laser are unfavorable for stable and repeatable generation of higher-order OAM, which needs the LPFG with small grating pitch. In order to solve this problem, a third-order OAM mode converter based on femtosecond microfabrication is proposed and fabricated for the first time. With the advantage of 4.4 μm focused spot size near the core, lower power and lower heat absorption efficiency, this method can be more stable and promising. Therefore, we first carry out the mode filed analysis and simulate the intensity and phase profiles of the superposed mode field in LP odd-even mode on different scales and phases patterns to obtain OAM mode. Second, we use the coupled-mode theory to analyze and simulate the transmission spectrum of LPFG, which guides the setting of the grating parameters such as the grating pitch, the depth of modulation and the length of the grating. By experimental verification, an asymmetric modulated long-period fiber grating with a pitch setting to 194 μm is fabricated on a six-mode fiber. The fundamental mode can be converted into the third-order angular linear polarization mode LP&lt;sub&gt;31&lt;/sub&gt; mode with 98% mode conversion efficiency near 1550 nm, and further converted into the OAM&lt;sub&gt;±3&lt;/sub&gt; modes by superposition of the odd and even LP&lt;sub&gt;31&lt;/sub&gt; mode with ±π/2 phase difference. At the same time, this fiber grating can also generate LP&lt;sub&gt;12&lt;/sub&gt; mode with 90% mode conversion efficiency near 1325 nm. Then we can take the same approach to transform LP&lt;sub&gt;12&lt;/sub&gt; mode into OAM modes with angular first-order as well as radial second-order. The experimental result is consistent with the simulation result. Thus, this scheme provides an idea for generating the high-order OAM modes in all-fiber systems by using only one grating with high repeatability.

A New Proposal Generalized Predictive Control Algorithm With Polynomial Reference Tracking Applied for Sodium Fast Reactors

This paper proposes a generalized predictive control (GPC) with constraints and orthonormal Laguerre functions using the simplified model of the primary system (reactor core and intermediate heat exchanger (IHX)) of a prototypical sodium fast reactor (SFR). This paper develops a multiple-input multiple-output (MIMO) GPC with input constraints able to track polynomial references of any degree applied in coolant temperature difference across the core and fractional power. The manipulated variables of the GPC-SFR are the reactivity and the sodium flow rate of the primary and secondary pipes. Moreover, orthonormal Laguerre functions and step down condition number techniques were also applied to avoid the numerical ill-conditioning issue in quadratic programming of large systems. Thus, a GPC type-2 was designed to control fractional power, coolant temperature difference across the core and sodium tank temperature of the SFR primary system when temperature references change according to a linear ramp after reaching their steady-state operation, sustaining 100% power operation on the reactor. In order to analyze the load tracking capability of the GPC-SFR type-2, the load following from 100% fractional power (FP) to 60% FP at 0.8% FP/min rate is simulated. Constraints on the rate of coolant temperature difference across the core and reactivity were applied for the design safety. For comparison criteria, this paper compares the GPC-SFR type-2 with the GPC-SFR type-1, i.e, standard model predictive control (MPC), to verify the viability and superior performance of the proposal regarding: (a) ramp-tracking capability of temperature and load; (b) the rejections of a reactivity disturbance of -1 cent and a secondary sodium inlet temperature disturbance of +10°F; and (c) a simulation with uncertainty in reactor design. The simulations show that the GPC-SFR type-2 overcome the GPC-SFR type-1 robustness and performance.