a b s t r a c t The corrosion behavior of X70 steel and iron in water-saturated supercritical CO2 mixed with SO2 was investigated using weight-loss measurements. As a comparison, the instantaneous corrosion rate in the early stages for iron in the same corrosion environment was measured by resistance relaxation method. Surface analyzes using SEM/EDS, XRD and XPS were applied to study the morphology and chemical composition of the corroded sample surface. Weight-loss method results showed that the corrosion rate of X70 steel samples increased with SO2 concentration, while the corrosion rate increased before decreasing with SO2 concentration for iron sample. Comparing resistance relaxation method results with weight-loss method results, it is found that the instantaneous corrosion rate of iron is much higher than the uniform corrosion rate of the iron tablet specimens which are covered with thick corrosion product films after a long period of corrosion. The corrosion product films were mainly composed of FeSO4 and FeSO3 hydrates. The possible reaction mechanism under such environment was also analyzed, and the electrochemical reaction between the dissolved SO2 in the condensed water film with iron is the critical reaction step. © 2011 Elsevier B.V. All rights reserved.

Impact of SO2 concentration on the corrosion rate of X70 steel and iron in water-saturated supercritical CO2 mixed with SO2

A mixed core for supercritical water-cooled reactors

Corrosion of engineering materials in a supercritical water cooled reactor: Characterization of oxide scales on Alloy 800H and stainless steel 316

The Supercritical water-cooled reactor (SCWR) design has been selected as one of the Generation IV reactor concepts because of its higher thermal efficiency and plant simplification compared to current light water reactors (LWRs). Reactor operating conditions call for a core coolant temperature between 280 and 620 °C at a pressure of 25 MPa and maximum expected neutron damage levels to any replaceable or permanent core component of 15 dpa (thermal reactor design) and 100 dpa (fast reactor design). Throughout the core, corrosion, stress corrosion cracking, and the effect of irradiation on these degradation modes are critical issues. This chapter reviews the current understanding of the response of candidate materials for SCWR systems, focusing on the corrosion and stress corrosion cracking response, and highlights the design trade-offs associated with certain alloy systems.

Material Performance in Supercritical Water

Due to the pressing needs to develop and improve compressors to be used in supercritical carbon dioxide Brayton (S-CO2) cycle, a 3D numerical study has been carried out for the full S-CO2 compressor geometry including diffuser and volute. The predictions were compared with measurements obtained from the recently constructed S-CO2 compressor test facility called SCO2PE (Supercritical CO2 Pressurizing Experiment), based on existing liquid water technology. The objective of the experimental and numerical work is to obtain fundamental data for the design optimization of compressor and to measure the overall performance near the critical point and in the supercritical state.

To simulate nonlinear behavior near the critical point of CO2, the fluid properties were implemented, via property table, in the computational analysis code. Before embarking in the CFD approach evaluation, a number of parametric runs were conducted to examine the order of errors induced by the property table resolution and to achieve grid convergence.

The steady-state numerical predictions using the k–ω SST model were found to return satisfactory results for liquid water and in the case of S-CO2 operating condition, quite far from the critical point. However, as the compressor operating condition approaches more toward the critical point; deviation from the reference data start to become more apparent. In the more challenging case, the disagreement with experimental data might be partially due to the modeling limitations but is also attributed to the subcritical region observed in the contour plot of the static pressure.

CFD investigation of a centrifugal compressor derived from pump technology for supercritical carbon dioxide as a working fluid

The supercritical water reactor (SCWR) has been the object of interest throughout the nuclear Generation IV community because of its high potential: a simple, direct cycle, compact configuration; elimination of many traditional LWR components, operation at coolant temperatures much higher than traditional LWRs and thus high thermal efficiency It could be said that the SWR was viewed as the water counterpart to the high temperature gas reactor

/pdf/feasibility-study-of-supercritical-light-water-cooled-51p5mhlxve.pdf

Feasibility Study of Supercritical Light Water Cooled Reactors for Electric Power Production

The use of supercritical temperature and pressure light water as the coolant in a direct-cycle nuclear reactor offers potential for considerable plant simplification and consequent capital and O&M cost reduction compared with current light water reactor (LWR) designs. Also, given the thermodynamic conditions of the coolant at the core outlet (i.e. temperature and pressure beyond the water critical point), very high thermal efficiencies of the power conversion cycle are possible (i.e. up to 46%). Because no change of phase occurs in the core, the need for steam separators and dryers as well as for BWR-type recirculation pumps is eliminated, which, for a given reactor power, results in a substantially shorter reactor vessel than the current BWRs. Furthermore, in a direct cycle the steam generators are not needed. If a tight fuel rod lattice is adopted, it is possible to significantly reduce the neutron moderation and attain fast neutron energy spectrum conditions. In this project a supercritical water reactor concept with a simple, blanket-free, pancake-shaped core will be developed. This type of core can make use of either fertile or fertile-free fuel and retain the hard spectrum to effectively burn plutonium and minor actinides from LWR spent fuel while efficiently generating electricity.

/pdf/feasibility-study-of-supercritical-light-water-cooled-fast-1d8kfpptpc.pdf

Feasibility Study of Supercritical Light Water Cooled Fast Reactors for Actinide Burning and Electric Power Production

The purpose of this collaborative Idaho National Engineering and Environmental Laboratory (INEEL) and Massachusetts Institute of Technology (MIT) Laboratory Directed Research and Development (LDRD) project is to investigate the suitability of lead or lead-bismuth cooled fast reactors for producing low-cost electricity as well as for actinide burning. The goal is to identify and analyze the key technical issues in core neutronics, materials, thermal-hydraulics, fuels, and economics associated with the development of this reactor concept. Work has been accomplished in four major areas of research: core neutronic design, plant engineering, material compatibility studies, and coolant activation. The publications derived from work on this project (since project inception) are listed in Appendix A.

/pdf/design-of-an-actinide-burning-lead-or-lead-bismuth-cooled-rus0a9qq6q.pdf

Design of an Actinide Burning, Lead or Lead-Bismuth Cooled Reactor that Produces Low Cost Electricity FY-01 Annual Report, October 2001

An experimental apparatus for the investigation of the flow-assisted dissolution and precipitation (corrosion) of potential fuel cladding and structural materials to be used in liquid lead alloy cooled reactors has been designed. This experimental project is part of a larger research effort between Idaho National Engineering and Environmental Laboratory (INEEL) and Massachusetts Institute of Technology to investigate the suitability of lead, lead-bismuth, and other lead alloys for cooling fast reactors designed to produce low-cost electricity as well as for actinide burning. The INEEL forced convection corrosion cell consists of a small heated vessel with a shroud and gas flow system. The gas flow rates, heat input, and shroud and vessel dimensions have been adjusted so that a controlled coolant flow rate, temperature, and oxygen potential are created within the downcomer located between the shroud and vessel wall. The ATHENA computer code was used to design the experimental apparatus and estimate the fluid conditions. The corrosion cell will test steel that is commercially available in the U. S. to temperatures above 650oC.

/pdf/a-technique-for-dynamic-corrosion-testing-in-liquid-lead-54wb9e0wac.pdf

A Technique for Dynamic Corrosion Testing in Liquid Lead Alloys

The Idaho National Engineering and Environmental Laboratory in investigating the feasibility of supercritical light water reactors for low-cost electric power production through a Nuclear Energy Research Initiative Project sponsored by the United State Department of Energy. The project is evaluating a variety of technical issues related to the fuel and reactor design, material corrosion, and safety characteristics. This paper presents the results of parametric calculations using the RELAP5 computer code to characterize the thermal-hydraulic response of supercritical reactors to transients initiated by loss-of-feedwater and turbine-trip events. The purpose of the calculations was to aid in the design of the safety systems by determining the time available for the safety systems to respond and their required capacities.

/pdf/a-parametric-study-of-the-thermal-hydraulic-response-of-5gbrgwojhn.pdf

Cliff Bybee Davis

Papers

Feasibility Study of Supercritical Light Water Cooled Reactors for Electric Power Production

Feasibility Study of Supercritical Light Water Cooled Fast Reactors for Actinide Burning and Electric Power Production

Design of an Actinide Burning, Lead or Lead-Bismuth Cooled Reactor that Produces Low Cost Electricity FY-01 Annual Report, October 2001

A Technique for Dynamic Corrosion Testing in Liquid Lead Alloys

A Parametric Study of the Thermal-Hydraulic Response of Supercritical Light Water Reactors During Loss-of-Feedwater and Turbine-Trip Events