Status of materials development for molten salt reactors

Lü

et al. 2013

Microsc. Res. Tech.

Hastelloy N alloy has been selected as the primary structure material for molten salt reactor. In this article, Hastelloy N alloy samples were irradiated to different doses at room temperature using 300 keV Ar(+) ions. The microstructural evolution was investigated by transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS). Black dot defects emerged in sample irradiated at low dose (0.4 displacement per atom (dpa)), and they grew up with irradiation doses (0.4-2 dpa). A high density of small dislocation loops (nano meters in size) were observed in the sample irradiated to 4 dpa. When the ion dose increased to 12 dpa, complicated structures with defects (including dislocation lines, larger loops and smaller black dots) were observed. Dislocation networks were detected from high-angle annular dark field (HAADF) images. Larger dislocation loops (size: 30-80 nm) were visible in the sample irradiated to 40 dpa. Irradiation with dose of 120 dpa led to the formation of face-centered cubic nanocrystallites with preferred orientations.

Section: Introductionmentioning

confidence: 99%

TEM investigation on the microstructural evolution of hastelloy N induced by Ar⁺ion irradiation

Lü

et al. 2013

Microsc. Res. Tech.

“…A large amount of corrosion data have been generated by ORNL and others on molten fuel salt corrosion for application in MSRs such as the Aircraft Reactor Experiment (ARE), MSRE, and the Molten Salt Breeder Reactor (MSBR) with review articles that summarize the results (Grimes et al 1972;McCoy 1967McCoy , 1969McCoy , 1970McCoy , 1971McCoy , and 1978Williams, Toth, and Clarno 2006).…”

Section: Materials Degradationmentioning

confidence: 99%

“…The establishment of aging reduction factors [HCB-II-2000-1(e)] was not within the scope of this effort. However, data pertaining to the effect of aging on subsequent creep-rupture was examined by McCoy (1971McCoy ( , 1978 and found to be minimal. As part of additional work, consideration should be given to adding Hastelloy N to Table HCB-II-2000-1(e) along with justification for the values.…”

Section: Recommendationsmentioning

confidence: 99%

Technology Development Roadmap for the Advanced High Temperature Reactor Secondary Heat Exchanger

Sabharwall¹,

McCllar²,

Siahpush³

et al. 2012

Date v EXECUTIVE SUMMARYThis Technology Development Roadmap (TDRM) study presents the path forward for deploying large-scale molten salt secondary heat exchangers and presents the benefits of using molten salt as the heat transport medium for advanced high temperature reactors. The roadmap will aid in the development and selection of the required heat exchanger for power production (the first anticipated process heat application), and other process heat applications, such as, hydrogen, methanol to gasoline, and ammonia production. It also (a) establishes the current state of readiness for molten salt secondary heat exchanger technology, (b) defines a path forward that systematically and effectively tests this technology to overcome areas of uncertainty, (c) demonstrates the achievement of an appropriate level of maturity prior to construction and plant operation, and (d) identifies issues and prioritizes future work for maturing the state of secondary heat exchangers technology.The TDRM was developed to identify the research and development activities, modeling, design, fabrication, and scaled testing that must occur to satisfy the requirements of advancing technological readiness. TDRMs provide the framework and structure required to systematically perform decision analysis, reduce risk, and mature technologies in a cost effective and timely manner. The roadmap uses the Technology Readiness Level (TRL) as a measure of the level of technical maturity of a technology, that is, the ability to design, fabricate, and deploy a component or system. The Secondary Heat Exchanger (SHX) is currently at a TRL-3 and the challenges addressed in this study must be overcome to mature this technology into a viable and reliable heat transfer system. Also addressed in this study is the potential future work, which will help in further enhancing the SHX TRL.This study discusses the results of a preliminary design analysis of the SHX. The efficient transfer of energy for industrial applications depends on the ability to incorporate cost-effective heat exchangers between the nuclear heat transport system and industrial process heat transport system. The heat exchanger required for AHTR is subjected to a unique set of conditions that bring with them several design challenges not encountered in standard heat exchangers. The somewhat corrosive molten salts, especially at higher temperatures, require materials throughout the system to avoid corrosion, and adverse high-temperature effects such as creep.Fuels salts received considerable testing and development in the Molten Salt Reactor Experiment (MSRE) program at Oak Ridge National Laboratory during the 1950s through 1970s, but relatively little research has been conducted on coolant salts. The corrosion data for various alloys in coolant salts (i.e., FLiBe, FLiNaK, KCl-MgCl 2 , NaNO 2 -NaNO 3 -KNO 3 and KF-ZrF 4 ) are too limited for reliable comparisons of corrosion resistance of the various alloys, or the relative aggressiveness of these molten salts.Tritium produced in the Advanced ...

“…There has been a large amount of corrosion data generated by ORNL and others on molten fuel salt corrosion for application in molten salt reactors such as the ARE, MSRE, and the Molten Salt Breeder Reactor (MSBR) with review articles that summarize the results (Grimes et al 1972;McCoy 1978;Williams, Toth, and Clarno 2006).…”

Section: Primary Molten Salt Primary System Materials Degradationmentioning

confidence: 99%

Feasibility Study of Secondary Heat Exchanger Concepts for the Advanced High Temperature Reactor

Sabharwall¹

2011

An evaluation of viable secondary heat exchanger concepts for use with a molten salt nuclear reactor is presented based on thermal design studies using KF-ZrF 4 as the secondary coolant. Along with the potential issues related to materials, fabrication methods, system configuration, coolant properties and hot corrosion, a discussion of challenges associated with integrating a steam power cycle with the reactor is also presented. The reference reactor design and configuration is a 3,400 MW t advanced high temperature reactor utilizing Rankine subcritical or supercritical cycles for power production. vi SUMMARYAdvanced High Temperature Reactors (AHTRs) will produce high outlet temperatures (704°C) using coated particle fuel, which provides for improved efficiency in power production or process heat for a variety of industrial applications. The AHTR is part of the fluoride-salt-cooled high temperature reactor (FHR) class of nuclear reactors included in the advanced reactor concept program. Early design decisions for the AHTR include use of an intermediate heat exchanger (IHX) to couple the primary loop to an intermediate loop. Heat from the IHX will be circulated in the intermediate loop through a secondary heat exchanger (SHX) and transferred to a power cycle that produces electricity or transferred to an industrial process. The feasibility of design options for the SHX is the subject of this study, and for the purposes of this study, the following preliminary decisions were made as a baseline for comparison:x The reactor outlet temperature is 704°C, from which the primary, secondary and tertiary fluid temperatures are derived. x The intermediate loop fluid is KF-ZrF 4 , which determines the SHX upstream side fluid and fluid conditions. x A supercritical or subcritical steam cycle is connected downstream of the SHX for power production, setting the fluid conditions on the downstream side. x The SHX is either a helically coiled tube and shell design or a printed circuit heat exchanger (PCHE) design. x The baseline material of construction is Alloy N.Alternative parameters are evaluated in this study and compared to the baseline based on the feasibility of their implementation.Heat exchangers are considered key components that need to be extensively investigated because they are operated under a severe environment and their performance is directly related to the overall system efficiency and safety. Previous analysis (INL/EXT-11-21584) of the power conversion system showed that Rankine subcritical and supercritical cycles with a turbine inlet temperature of 679°C can yield conversion efficiencies of 42% and 44% respectively, with KF-ZrF 4 as the secondary salt coolant.Fluoride salts such as KF-ZrF 4 have highly desirable characteristics for high temperature nuclear reactor heat transport. A characteristic of molten fluoride salts is that they can easily dissolve passive oxide layers such as the chromia oxide film (Cr 2 O 3 ) that provides the corrosion resistance for stainless steels and nickel based alloys...