Water Pressure Research Articles

Scale effects on core design, fuel costs, and spent fuel volume of pressurized water reactors

The desire to improve the economic competitiveness and deployment pace of nuclear energy through modularization, manufacturing, and series production had led to the development of smaller size reactors. As the standard 17x17 fuel technology is mainly maintained in the pressurized water reactors (PWRs) category, this translates into a lower number of fuel assemblies in the core and sometimes a reduced fuel height. To assess the impact of such scale change in core design on fuel cycle cost and spent fuel volume, a scoping analysis tool is developed based on infinite lattice calculations, leakage, fuel management reduced models, and levelized unit cost of electricity (LCOE) estimate. As such, cost dynamics driven by fuel specific power, burnup, core leakage, feed, cycle length, fuel assembly height as well as uranium market data are captured with consistent set of assumptions and analysis methods. A selection of 5 reactor designs representative of leading PWR developers is assessed and compared. Pursuing higher specific powers and optimal burnups are highlighted as the main fuel cost reduction drivers, nevertheless, practical limitations and opportunities must be evaluated to establish the feasibility of such enhanced fuel operation. In consequence, a detailed core design is performed using SIMULATE3 code for 5 PWR variations including natural and forced coolant circulation modes, two reactor scales, power densities of 73, 112, and 123 kW/l and higher discharge burnups. Design and optimization are performed at the lattice level, for the reflector, and at the core loading level. Satisfactory steady-state operation including power distribution, coolant operating limits, and reactivity requirements are analyzed and reported in this paper. The fuel economics of the detailed core designs confirm the scoping analysis findings. Despite the unlocked power uprates in small PWRs, the achievable burnup for a given fuel specific power requires more enrichment and shorter fuel height results in higher fabrication costs per mass of fuel, which makes scaling down core size a more expensive endeavor on the fuel cycle front. Spent fuel volumes are reported for the PWRs designed in this paper. These volumes are driven by the core average discharge burnup regardless of the scale in consideration. Additional cost and core performance aspects related to heavy reflector gains, fuel-reflector substitution, and disposal cost policy in the U.S. are examined.

Diagnosis of Polymer Electrolyte Fuel Cell: Should We Rely Only on Electrical Quantities?

Polymer electrolyte fuel cells (PEMFC) will play a central role in the establishment of a de-carbonized society. They are seen as a key technology to empower electric heavy-duty vehicles. However, the lifespan is still below the fixed standards for their commercialization. A way to increase their durability is to complement them during operation with a mitigation strategy enabling to avoid the arise of faulty states accelerating degradation processes. Nowadays, most of the proposed fault identification and isolation architectures rely on monitoring of the performance through electrochemical impedance spectroscopy (EIS). Nevertheless, the analysis of impedance data is often complicated, since the contribution of many processes in the EIS spectra are coupled with each other and, for this reason, difficult to identify. This constitutes a limiting factor for its employment as diagnostic tool. In the last years, in order to overcome such issues, the use of nonelectrical periodic inputs and/or outputs has been advanced. The idea motivating this research direction is the possibility to detect the contribution of selected processes on the performance of PEMFCs separating them from the others. Novel frequency response techniques involving back pressure, temperature and partial pressure have been developed [1].In this contribution, the so-called concentration frequency response analysis (CFRA) is considered [2, 3]. It consists on perturbing the cathode side of the cell with a feed characterized by a periodic partial pressure of oxygen and water, and the detection of the electric response, voltage or current. A test station has been designed and constructed in order to apply this technique and investigate its capabilities. A model based analysis of the measured CFRA spectra indicates the possibility to decouple the contributions of the water transport into Nafion and oxygen mass transport on the performance of the cell depending on the chosen concentration input and electrical output. In this way, the analysis and identification of the related power losses is simplified with respect to classic EIS.Moreover, the performance of a fault identification and isolation architecture employing CFRA as monitoring technique have been evaluated and compared to EIS. For such purpose, an identifiability analysis of parameters related to faulty states and obtained by model fitting to spectra of each technique has been performed. The results clearly show that the employment of CFRA based on water pressure input offers the most reliable parameter estimation and, consequently, constitutes the most preferable diagnosis method among the others analyzed.

Design and Performance Evaluation of a Specialized Bubbler System for Accurate and Repeatable Solid Oxide Electrolysis Cell (SOEC) Testing

Accurate assessment of Solid Oxide Electrolysis Cell (SOEC) performance demands standardized testing conditions, particularly in stable steam delivery. Fluctuations in steam concentration and flow rate can significantly impact measured open-circuit voltage (OCV) and polarization behavior. Although direct steam injection is straightforward, it is often hindered by instability resulting from intermittent liquid water flux, pressure fluctuations, and fractional distillation effects. Bubbler humidification systems have the potential to offer consistent steam, but tailored designs for SOEC testing are currently absent.This study introduces a specialized bubbler system designed to deliver stable steam to SOEC test stands accommodating both oxygen-conducting (O-SOEC) and proton-conducting (H-SOEC) cells. The bubbler components include a refill water reservoir, a level control module, heating elements, pressure relief valves, check valves, tubing, and fittings integrated with the test stand. The system humidifies the sweep gas, transporting steam to the cell test fixture situated within a high-temperature furnace.The design process involved meticulous considerations of materials compatibility, hydrogen safety, and overtemperature protection. All wetted components employ stainless steel, glass, or PTFE materials in their construction construction. Redundant thermocouples ensure safe process temperatures with automated overtemperature shut off. The refill reservoir and bubbler headspace operate near ambient pressure, facilitated by an exhaust line vent sized for minimal backpressure.In various executed O-SOEC tests, the bubbler maintained OCV stability within ±5 mV over several hundred hours for each cell operating at 750°C, eliminating spikes caused by steam fluctuations observed with direct injection methods. This facilitates precise electrochemical analysis and determination of area-specific resistance losses. Polarization curves align with expected behavior based on the Nernst equation. The system has demonstrated safe and stable functionality for over thousands of hours across various operating conditions.The bubbler design presents researchers with notable advantages over existing steam supply options for SOEC test stands, addressing performance, safety, and flexibility concerns. Online instrumentation enables closed-loop control of steam conditions, enhancing stability. Standardization of test equipment is crucial for quality results, and this work contributes progress toward reproducible protocols in the international SOEC community. The modular bubbler approach, integrated with safety features, also signifies safer methodology choices for lab-scale experimental research.

Simulation of a Passive Osmosis-Integrated Electrolyzer for Seawater Electrolysis

The requirement for extremely pure water in electrolysis, combined with the abundant presence of seawater, has prompted extensive research into the creation of direct seawater electrolysis technology for decades [1]. However, these efforts have had limited success due to other limiting issues that arise, including competition with the chloring evolution reaction, increased membrane resistance, corrosion of electrode materials and electrode scaling due to the presence of multivalent cations. To avoid these issues, seawater is typically first desalinated using reverse osmosis, but that comes with additional energy cost. Therefore, our project has proposed a new reactor that integrates passive osmosis (extracting fresh water from seawater) with electrolysis.In this presentation, we will discuss the operation of the osmosis-integrated electrolyzer and show theoretical predictions of the osmotic pressure differential and water flux/velocity profiles under different conditions. The numerical model that will be presented was applied to three different cell designs that have been physically developed. The first cell consists of two anion exchange membranes (AEMs) with two side chambers containing KOH and a middle chamber containing Sodium Chloride (NaCl). The second cell has KOH in one outer compartment and H2SO4 in the other. The central compartment containing NaCl is separated from KOH compartment by an AEM and the H2SO4 compartment by a cation exchange membrane (CEM). The third cell eliminates the central compartment and allows the osmosis to occur outside of the cell.The simulation results show that by increasing the concentration of KOH and H2SO4 in the side chambers for all three models, the amount of water transferred from the middle chamber, containing of NaCl to the side chambers increases. The simulation results were validated by experiments (Figure 1). In addition, the model is able to quantify the transport of ions in the system, including chloride ions through the AEM. Lastly, the mass transfer model is integrated with an electrochemical model where an anode and cathode are added to the system to consume the water that is transported through the membranes.Reference:[1] M. A. Khan, T. Al-Attas, S. Roy, M. M. Rahman, N. Ghaffour, V. Thangadurai, S. Larter, J. Hu, P. M. Ajayan, and M. G. Kibria, “Seawater electrolysis for hydrogen production: a solution looking for a problem?” Energy & Environmental Science, 14, 4831 (2021). Figure 1

Numerical investigations on the performance of coupled NCL based passive heat removal system of an IPHWR

Passive heat removal systems (PHRS) are indispensable additional safety features in nuclear reactors to deal with station blackout (SBO) conditions. These systems are based on coupled natural circulation loops (C-NCL) connected in series configuration. Further, these system's design, operating conditions, working fluid, heat removal capacity, etc., are specific to the reactor type. In the present work, the operational performance of such first of a kind PHRS of 700 MWe Indian pressurized heavy water reactor (IPHWR) is investigated. For this purpose, a coupled two-phase NCL code is developed, validated and employed. This PHRS consists of two NCLs connected in HHVC-VHVC (horizontal heater and vertical cooler - vertical heater and vertical cooler) configuration. In this study, initially, the full power reactor thermal-hydraulic conditions are established, subsequently, the performance of the PHRS under SBO is investigated. The analyses demonstrated that the system is adequate to effectively eradicate the decay heat by establishing single and two-phase natural circulation (NC) flows of ∼4.5 % and ∼5.6 % of rated conditions in primary and secondary transport loops, respectively. The maximum PHRS capability is predicted to be ∼72 MWth which is more than 3 % of full power. The transients of flow, pressure, energy transfer and heat sink thermal conditions are analyzed when the system changes from forced to NC. Further, the influence of system conditions such as loop diameter, loop height, sink volume, sink temperature and heat exchanger area on PHRS performance was predicted and the changes in system parameters were analyzed. The vital parameters influencing the PHRS performance are identified based on sensitivity analyses. This investigation provides significant insight into the flow and heat transfer characteristics of two-phase and coupled NCLs in the PHRS.

Strain response law of large-diameter PCCPs under internal water pressure based on BOTDA

Prestressed concrete cylinder pipes (PCCPs) are widely used in trans-regional large-scale water conveyance projects, so it is of great significance to monitor their condition. In this paper, the Brillouin Optical time domain analysis (BOTDA) sensing system is used to measure the circumferential strain of PCCPs under internal water pressure. The test results show that BOTDA technology can accurately monitor the shape variable of the outer wall of the pipe. Moreover, the circumferential strain is not uniform, and there are multiple relative maxima and minima. When the internal water pressure is 1.2 MPa, the absolute maximum and minimum strain is 579.17με and 217.78με respectively. In addition, there is a positive linear correlation between the strain and the internal water pressure, but the hysteresis effect is obvious in the case of insufficient water filling. This study provides reliable experimental data for the application of distributed optical fiber sensing technology in large-diameter water pipelines.

Counterintuitive Trend of Intrusion Pressure with Temperature in the Hydrophobic Cu2(tebpz) MOF.

Liquid porosimetry experiments reveal a peculiar trend of the intrusion pressure of water in hydrophobic Cu2(3,3',5,5'-tetraethyl-4,4'-bipyrazolate) MOF. At lower temperature (T) range, the intrusion pressure (Pi) increases with T. For higher T values, Pi first reaches a maximum and then decreases. This is at odds with the Young-Laplace law, which for systems showing a continuous decrease of contact angle with T predicts a corresponding reduction of the intrusion pressure. Though the Young-Laplace law is not expected to provide quantitative predictions at the subnanoscale of Cu2(tebpz) pores, the physical intuition suggests that to a reduction of their hydrophobicity corresponds a reduction of the Pi. Molecular dynamics simulations and sychrothron experiments allowed to clarify the mechanism of the peculiar trend of Pi with T. At increasing temperatures the vapor density within the MOF' pores grows significantly, bringing the corresponding partial pressure to ≈5MPa. This pressure, which is consistent with the shift of Pi observed in liquid porosimetry, represents a threshold to be overcame before intrusion takes place. Beyond some value of temperature, the phenomenon of reduction of hydrophobicity (and water surface tension) dominated over the opposite effect of increase of vapor pressure and Pi inverts its trend with T.

Effect of dissolved KOH and NaCl on the solubility of water in hydrogen: A Monte Carlo simulation study.

Vapor-Liquid Equilibria (VLE) of hydrogen (H2) and aqueous electrolyte (KOH and NaCl) solutions are central to numerous industrial applications such as alkaline electrolysis and underground hydrogen storage. Continuous fractional component Monte Carlo simulations are performed to compute the VLE of H2 and aqueous electrolyte solutions at 298-423K, 10-400bar, 0-8 molKOH/kg water, and 0-6 molNaCl/kg water. The densities and activities of water in aqueous KOH and NaCl solutions are accurately modeled (within 2% deviation from experiments) using the non-polarizable Madrid-2019 Na+/Cl- ion force fields for NaCl and the Madrid-Transport K+ and Delft Force Field of OH- for KOH, combined with the TIP4P/2005 water force field. A free energy correction (independent of pressure, salt type, and salt molality) is applied to the computed infinite dilution excess chemical potentials of H2 and water, resulting in accurate predictions (within 5% of experiments) for the solubilities of H2 in water and the saturated vapor pressures of water for a temperature range of 298-363K. The compositions of water and H2 are computed using an iterative scheme from the liquid phase excess chemical potentials and densities, in which the gas phase fugacities are computed using the GERG-2008 equation of state. For the first time, the VLE of H2 and aqueous KOH/NaCl systems are accurately captured with respect to experiments (i.e., for both the liquid and gas phase compositions) without compromising the liquid phase properties or performing any refitting of force fields.

Continuous low water pressure dissection technique minimizing air bubbles during underwater endoscopic submucosal dissection.

Continuous low water pressure dissection technique minimizing air bubbles during underwater endoscopic submucosal dissection.

Assessment of piles’ resistance driven sequentially in fine-grained soils using pile load tests

This paper presents a field pile load test program conducted on four 0.36 m closed-end steel pipe (CEP) piles with lengths ranging between 11 to 13 m installed in fine-grained soils. Subsurface investigations with standard penetration tests (SPT) and cone penetration tests (CPT) with pore pressure measurements were performed at the site. Three pushed-in piezometers at incremental offsets from the piles were also installed to monitor pore water pressure changes during and after the installation of piles. Several dynamic load tests (DLT) were performed at different times to observe the change in pile resistance. A static load test (SLT) was also performed on one of the piles. Some load test results showed an unexpected decrease in the resistances of some piles with time. The study showed that construction activities, e.g. installation of other piles, disturbs the soil and groundwater conditions which can significantly affect the pile resistance measured during load tests. This investigation revealed that pile driving and restrikes should be scheduled such that the effect of construction activities on load tests results will be avoided or minimized.

The impact of lenses on the seepage failure of tailings dam.

The presence of lenses such as tailings slurry, frozen soil, and saturated zones disrupts the continuity of tailings dams and their normal seepage patterns, elevating the seepage line of the dam body and significantly impacting local stability. This study, to investigate how lenses affect the stability and failure mechanisms of tailings dams, employs numerical simulation and physical models and constructs a model of the tailings dam, incorporating tailings clay lens and void lens, to investigate variations in hydraulic gradients, seepage velocities, seepage flow, pore water pressure, and the patterns of seepage failure. This research reveals that the tailings clay lens within the dam body increases the hydraulic gradient in its vicinity due to its low permeability and raises the phreatic line. As the tailings clay lens approaches the dam body, the phreatic line tends to escape along the upper part of the lens towards the dam surface. In addition, the void lens could lead to a more pronounced seepage gradient along its path on the dam surface, with a liquefaction beneath it. As the void lens nears the toe of the slope, the dam failure mode transitions from a step-like progressive failure to an arch-shaped settlement failure along the void lens.

Influence of drainage conditions on piezocone penetration mechanism in offshore clays

ABSTRACT CPTu (piezocone penetration test) is widely used in engineering practice to determine various parameters of clays under partially drained conditions. However, most existing research is based on undrained or fully drained conditions for clays, leading to underestimation or overestimation of soil strength. By applying the Eulerian-Lagrangian large deformation finite element method to analyse the water-soil interaction, the CPTu driving mechanism in offshore saturated soft clays under different drainage conditions is revealed. An advanced hypoplastic constitutive model for clays is used to simulate the nonlinear behaviour of kaolin under different drainage conditions. The generation, accumulation, and dissipation of excess pore water pressure under different drainage conditions are analysed, as well as the influence of excess pore water pressure on cone tip resistance and the effective stress of the soil during the CPTu penetration process.

Preliminary Validation of Persulfate Delivery Through Porous Pipe in the Vadose Zone: A Two-Dimensional Sandbox Experiment

ABSTRACT When remediating contamination in the vadose zone, which is a potential source of continuous groundwater and surface water pollution, technical challenges are often encountered. In this study, the feasibility of delivering sodium persulfate (SPS) oxidant to unsaturated soils was explored by integrating porous pipes, commonly used in agriculture, with in-situ chemical oxidation (ISCO). An evaluation of the operating characteristics of the pipe determined a recommended influent rate of < 0.1 L min−1 and an initial influent water pressure < 20 kPa to prevent percolation pore enlargement. Two-dimensional sandbox experiments revealed that pulse infiltration at an influent rate of 0.05 L min−1 was effective in creating matrix flow and lateral movement, minimizing preferential flow induced by continuous infiltration. Application of SPS (10% by wt.) under these conditions resulted in approximately 90% wetting of the sandbox area SPS flow at the experimental time that infiltrated from the pipe. After a 14-d post infiltration resting state, residual SPS concentrations ranged from 6,000 -12,000 mg/kg in soil, with soil pH levels of 3–4, ORP around 600 mV, and 40–60% decreases in soil organic carbon. This developed method helps retain the oxidant and promote chemical reactions, making ISCO a viable option for remediating unsaturated soil contamination.

An enhanced mathematical model for evaluating grid-to-rod fretting wear under complex boundary

Grid-to-rod fretting wear is a significant cause of fuel failure in pressurized water reactors and poses a challenge in fuel performance evaluation. As burnup increases, neutron irradiation can lead to complex changes in the grid-to-rod system, affecting its dynamic behavior. This paper presents an enhanced mathematical model that can simulate the coupled axial-lateral motion and complex boundary conditions, including relaxation support, friction, and gap constraint. Through multiple parametric studies, the model has revealed valuable results. Notably, grid relaxation of 10%–30% significantly impacts wear. Multiple critical excitation frequencies can cause drastic changes in vibration and wear. The increase in holding force due to rod swelling and the early opening of the gap due to creep down require careful attention. Moreover, the effect of axial force on changes in natural frequency and increased wear should be considered.

Transient hydraulic analysis of the water delivery pipeline in mountainous areas for cascade pressurized pump stations

ABSTRACT Aiming at the problem that cascade pressurized pump stations in mountainous areas are more prone to pump shutdown accidents compared to single-stage pressurized pump stations. Various pump shutdown accidents that may occur in the pressurized water supply system of the terrace pumping station were analyzed in a targeted manner. Additionally, it was also explored that in addition to water hammer protection measures, remote-control measures for water pumps based on PLC (Programmable Logic Controller) may be used to reduce the severity of accidents. A single-factor experimental method was used to numerically analyze various accident conditions of a simplified model of a three-stage series pressurized water delivery system consisting of a water intake pump station, a midway pump station, and a final-stage pump station, without water hammer protection devices. The impact of different control variables on the transient hydraulic calculations of pumping stations at all levels was evaluated. The results showed that optimizing the precedence of shutdowns, and the sequential shutdown times of each stage pump station could be assisted to some extent in water hammer protection by the PLC. This provides technical support and detailed optimization for the scientific control of cascade booster pumping stations in mountainous areas.

Analytical Method of Spatiotemporal Evolution Characteristics of Unsteady Seepage Flow Pore Water Pressure in Front of Tunnel Face

Analytical Method of Spatiotemporal Evolution Characteristics of Unsteady Seepage Flow Pore Water Pressure in Front of Tunnel Face

A Study on the Factors Controlling the Kinematics of a Reactivated and Slow-Moving Landslide in the Eastern Liguria Region (NW Italy) through the Integration of Automatic Geotechnical Sensors

This paper deals with the investigation of factors influencing the movement patterns of a reactivated slow-moving landslide situated in the eastern Liguria region (NW Italy) through the analysis of extensive ground-based hydrological and geotechnical monitoring data. Subsurface horizontal displacement and pore water pressure data were acquired simultaneously by means of automatic sensors positioned at pre-existing and localized failure zones. The joint examination of field measurements enabled us to explore the connections between rain, pore water pressure, and displacements. The results of continuous displacement monitoring showed that the landslide kinematics involved phases of extremely slow movements alternated with periods of relative inactivity. Both stages occurred prevalently at seasonal scale displaying similar durations. The slow-motion phases took place at relatively constant pore water pressure and were ascribed to mechanisms of viscous shear displacements along failure surfaces. Inactive phases entailed no significant deformations, mostly corresponding to prolonged dry periods. The two motion patterns were interrupted by episodic sharp deformations triggered by delayed (preparation periods from 4 to 11 days) rainfall-induced pore water pressure peaks, which were ascribed to sliding mechanisms taking place through rigid-plastic frictional behaviour. During these deformation events, hysteresis relationships between pore water pressure and displacement were found, revealing far more complex hydro-mechanical behaviour.

Effect of Heat Exchange Area Margins on Thermal Characteristics of the Heat Exchange System in the Pressurized Water Test Loop during Fuel Assembly Irradiation

The performance of heat exchangers in the pressurized water test loop is a critical factor in ensuring the achievement of irradiation parameters for fuel assemblies and the safety of experimental operations. The effect of the heat exchange area margin on the heat exchangers in the pressurized water test loop for the fuel assembly during the steady-state irradiation is analyzed. Additionally, optimization methods for determining the margin of heat exchange area and corresponding design strategies are further investigated. It shows that the effect of the heat exchange area margin on the heat exchange power is less affected by the inlet temperature of the primary water and is primarily influenced by the flow rate of the primary water. A decrease in the flow rate of the primary water reduces the compensatory effect of the cooling section on power and enhances the weakening effect of the regeneration section on power. Meanwhile, the correspondence between the margin of the regeneration section and the cooling section, established based on design conditions, can be applicable when there are changes in the inlet temperature of the primary water, but it is not suitable when there are changes in the flow rate of the primary water. When the flow rate of the primary water decreases, the cooling section margin required to compensate for the decrease in power caused by the regeneration section margin will increase significantly. In addition, short-circuiting the heat exchange tubes in the regeneration section can effectively enhance the heat transfer capability. Furthermore, setting the heat exchange area margins of the regeneration and cooling sections to zero can serve as a termination condition for iterative calculations in the verification of regenerative heat exchangers under off-design conditions.

Influence of suction pressure of clay unsaturated soils on slope stability

Background. The main aspects of the influence of suction pressure on slope stability are considered; an example of calculations in the Plaxis software is presented. Specific features in the behavior of unsaturated and saturated soils are described. A model for describing the behavior of saturated soil under the influence of suction pressure is proposed.Aim. Soviet hydrophysic and soil scientists actively explored the relationship between capillary-sorption (structural or matrix) water pressure in the soil and humidity. However, the introduction of foreign methods and software based thereon into the engineering and geological practice of calculating the stability of slopes has raised the question about the influence of suction pressure of clay soils on the stability of slopes. Materials and methods. The main research material was loams of the Moscow glaciation. Simulation was carried out based on the Muallem — van Genuchten model.Results. The simulation results showed that suction pressure and capillarity directly affect the slope stability coefficient, provided that the similarity of other model parameters.

Numerical simulations and an experimental study for optimal design of a 1500 [formula omitted] water-tube condensing boiler

The present study is focused on investigating the condensation process and numerical simulation for optimal design of a 1500 kW water-tube condensing boiler. The specific geometry of the heat exchanger of this boiler involves compact arrangement of spiral coils to enhance heat transfer efficiency and achieve high capacity. Experimental validation is conducted on a 580 kW condensing boiler. Numerical simulations of the flow for gas and water sides of the boiler are performed in parallel using the ANSYS-FLUENT software with the k-omega (SST) turbulence model. Twelve models with different combustion chamber dimensions, coil numbers and revolutions are considered. Important design criteria include flue gas temperature, combustion chamber pressure and water pressure drop in the coils. The results indicate that increasing effective heating surface area and reducing coils gap decrease flue gas temperature to the dew point. Increasing coil revolutions has a greater impact on flue gas temperature and boiler weight compared to increasing coil numbers. With the same number of coils, by adding an extra revolution the weight is increased approximately 17 % and the effective heating surface area about 21 %. On the other hand, for the same number of revolutions, each additional spiral coil increases both of the weight and the effective heating surface area approximately 4 %. Moreover, with an increase in the number of the coils and a decrease in the number of revolutions, the pressure within the combustion chamber is decreased. By reducing the gap size, the flue gas temperature is reduced approximately 2 °C and the combustion chamber pressure is increased about 18 %. Base on the design criteria, the model six with 27 spiral coils and 7–8 revolutions, is identified as the optimal design. This progress and capability allows the design and manufacture of high-capacity boilers for residential sector as well as for industrial applications.