scholarly journals Molten Salt Reactor Characteristics Involving Fuel Salt Flow and Temperature Distribution in the Steady State

2003 ◽  
Vol 2 (4) ◽  
pp. 400-407
Author(s):  
Koshi MITACHI ◽  
Takahisa YAMAMOTO ◽  
Takashi SUZUKI ◽  
Yoshihide OKUMURA
Keyword(s):  
Steady State ◽  
Temperature Distribution ◽  
Molten Salt ◽  
Molten Salt Reactor ◽  
Fuel Salt ◽  
Salt Flow

Steady State Analysis of Molten Salt Reactor in Consideration of the Effect of Fuel Salt Flow

2004 ◽  
Author(s):  
Takahisa Yamamoto ◽  
Koshi Mitachi ◽  
Takashi Suzuki
Keyword(s):  
Steady State ◽  
Thermal Neutron ◽  
Molten Salt ◽  
Fuel Cycle ◽  
Molten Salt Reactor ◽  
Delayed Neutron ◽  
Steady State Analysis ◽  
Fuel Salt ◽  
Salt Flow ◽  
State Analysis

The Molten Salt Reactor (MSR) is a thermal neutron reactor with graphite moderation and operates on the thorium-uranium fuel cycle. The feature of the MSR is that fuel salt flows the inside of the reactor accompanying nuclear fission reaction. In the previous study, the authors had developed numerical model to simulate the effects of the fuel salt flow on the reactor characteristics. This paper applies the model to the steady state analysis of the small MSR system and estimates the effects of the fuel flow. The model consists of two group diffusion equations for fast and thermal neutron fluxes, balance equations for six-group delayed neutron precursors and energy conservation equations for fuel salt and graphite moderator. The following results are obtained: (1) the fuel salt flow affects the distributions of the delayed neutron precursors, especially long-lived one, and (2) the extension of residence time in the external loop system and the rise of fuel inflow temperature slightly show negative reactivity effects, decreasing neutron multiplication factor of the small MSR system.

New Design of Thorium Molten Salt Reactor Core and Preliminary Safety Analysis

2017 ◽  
Author(s):  
Chen Qi-chang ◽  
Si Sheng-yi ◽  
Zhao Jin-kun ◽  
Bei Hua
Keyword(s):  
Steady State ◽  
Temperature Distribution ◽  
Molten Salt ◽  
Power Level ◽  
Operating Conditions ◽  
Molten Salt Reactor ◽  
Negative Power ◽  
Pump Speed ◽  
Fuel Salt ◽  
Thorium Molten Salt Reactor

In order to improve the breeding ratio and core safety, new thorium molten salt reactor (TMSR) core is designed. The new designed TMSR core is composed of hexagon moderator elements, which contain SiC tube to form a central fuel channel and employs BeO as moderator. The composition of the fuel salt, adopted in this core, is also optimized. Based on this core design, steady state and transient safety characteristic of TMSR are preliminarily analyzed using coupled multi-physics code. Power/temperature distribution and reactivity coefficients are analyzed for the steady state core, which demonstrated that the core has flat temperature distribution and large negative power coefficients at all power level. Transient simulations are carried out for power start-up, pump speed variation, loss of heat sink and so forth, the temperature and power response are also analyzed. The results indicate that the TMSR core power and temperature are closely related to the control rod position, velocity of flow and composition of fuel salt, and the new designed TMSR has excellent performance of safety under various operating conditions.

Reactor Controllability of 3-Region-Core Molten Salt Reactor System: A Study on Load Following Capability

2006 ◽  
Author(s):  
Takahisa Yamamoto ◽  
Koshi Mitachi ◽  
Masatoshi Nishio
Keyword(s):  
Molten Salt ◽  
Solid Fuel ◽  
Molten Salt Reactor ◽  
Delayed Neutron ◽  
Reactor Kinetics ◽  
External Loop ◽  
Fuel Salt ◽  
Salt Flow ◽  
Point Reactor Kinetics ◽  
Graphite Moderator

The Molten Salt Reactor (MSR) systems are liquid-fueled reactors that can be used for actinide burning, production of electricity, production of hydrogen, and production of ssile fuels (breeding). Thorium (Th) and uranium-233 (233U) are fertile and ssile of the MSR systems, and dissolved in a high-temperature molten fluoride salt (fuel salt) with a very high boiling temperature (up to 1650K), that is both the reactor nuclear fuel and the coolant. The MSR system is one of the six advanced reactor concepts identified by the Generation IV International Forum (GIF) as a candidate for cooperative development [1]. In the MSR system, fuel salt flows through a fuel duct constructed around a reactor core and fuel channel of a graphite moderator accompanied by fission reaction and heat generation, and flows out to an external-loop system consisted of a heat exchanger and a circulation pump. Due to the motion of fuel salt, delayed neutron precursors that are one of the source of neutron production make to change their position between the ssion reaction and neutron emission events and decay even occur in the external loop system. Hence the reactivity and effective delayed neutron precursor fraction of the MSR system are lower than those of solid fuel reactor systems such as Boiling Water Reactors (BWRs) and Pressurised Water Reactor (PWRs). Since all of the presently operating nuclear power reactors utilize solid fuel, little attention had been paid to the MSR analysis of the reactivity loss and reactor characteristics change caused by the fuel salt circulation. Sides et al. [2] and Shimazu et al. [3] developed MSR analytical models based on the point reactor kinetics model to consider the effect of fuel salt flow. Their models represented a reactor as having six zones for fuel salt and three zones for the graphite moderator. Since their models employed the point reactor kinetics model and the rough temperature approximation, their results were not sufficiently accurate to consider the effect of fuel salt flow.

Numerical Research on Steady Coupling of Neutronics and Thermal-Hydraulics for a Molten Salt Reactor

2008 ◽  
Author(s):  
Dalin Zhang ◽  
Changliang Liu ◽  
Libo Qian ◽  
Guanghui Su ◽  
Suizheng Qiu
Keyword(s):  
Thermal Neutron ◽  
Molten Salt ◽  
Molten Salt Reactor ◽  
Thermal Hydraulics ◽  
Steady Condition ◽  
Delayed Neutron ◽  
The Core ◽  
Production Of Hydrogen ◽  
Fuel Salt ◽  
Salt Flow

The Molten Salt Reactor (MSR), which is one of the ‘Generation IV’ concepts, can be used for production of electricity, actinide burning, production of hydrogen, and production of fissile fuels. In this paper, a single-liquid-fueled MSR was selected for conceptual research. For this MSR, a ternary system of 15%LiF-58%NaF-27%BeF2 was proposed as the reactor fuel solvent, coolant and also moderator with ca. 1 mol% UF4 dissolving in it, which circulates through the whole primary loop accompanying fission reaction only in the core. The fuel salt flow makes the MSR different from the conventional reactors using solid fissile materials, and makes the neutronics and thermal-hydraulic coupled strongly, which plays the important role in the research of reactor safety analysis. Therefore, it’s necessary to study the coupling of neutronics and thermal-hydraulic. The theoretical models of neutronics and thermal-hydraulics under steady condition were conducted and calculated by numerical method in this paper. The neutronics model consists of two group neutron diffusion equations for fast and thermal neutron fluxes, and balance equations for six-group delayed neutron precursors considering flow effect. The thermal-hydraulic model was founded on the base of the fundamental conservation laws: the mass, momentum and energy conservation equations. These two models were coupled through the temperature and heat source. The spatial discretization of the above models is based on the finite volume method (FVM), and the thermal-hydraulic equations are computed by SIMPLER algorithm with domain extension method on the staggered grid system. The distribution of neutron fluxes, the distribution of the temperature and velocity and the distribution of the delayed neutron precursors in the core were obtained. The numerical calculated results show that, the fuel salt flow has little effect to the distribution of fast and thermal neutron fluxes and effective multiplication factor; however, it affects the distribution of the delayed neutron precursors significantly, especially long-lived one. In addition, it could be found that the delayed neutron precursors influence the neutronics slightly under the steady condition, and the flow could remove the heat generated by the neutron reactions easily to ensure the reactor safe. The obtained results serve some valuable information for the research and design of this new generation reactor.

Steady state investigation on neutronics of a molten salt reactor considering the flow effect of fuel salt

2008 ◽  
Vol 32 (8) ◽  
pp. 624-628 ◽  
Author(s):  
Zhang Da-Lin ◽  
Qiu Sui-Zheng ◽  
Liu Chang-Liang ◽  
Su Guang-Hui
Keyword(s):  
Steady State ◽  
Molten Salt ◽  
Molten Salt Reactor ◽  
Flow Effect ◽  
Fuel Salt

A Theory and Model of Molten Salt Reactor Xenon Behavior After the Solubility Limit

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Terry J. Price ◽  
Ondrej Chvala
Keyword(s):  
Steady State ◽  
Molten Salt ◽  
Solid Fuel ◽  
Qualitative Difference ◽  
Solubility Limit ◽  
Molten Salt Reactor ◽  
Fuel Reactor ◽  
Fuel Salt ◽  
Reactor Operating ◽  
Theory And Model

Abstract Due to the circulating nature of the fuel, there is a qualitative difference between xenon behavior in a molten salt reactor (MSR) compared to a solid fuel reactor. Therefore, the equations that describe 135Xe behavior in a molten salt reactor must be formulated differently. Prior molten salt reactor xenon models have focused on behavior below a solubility limit in which the 135Xe is partially dissolved in the fuel salt. It is foreseeable that a molten salt reactor may operate with a concentration of gas dissolved in the salt sufficiently high such that no further gas may dissolve in the fuel salt. This paper introduces a theory of molten salt reactor xenon behavior for a reactor operating above the solubility limit. A model was developed based on this theory and analyses performed are discussed. Results indicate: (1) steady-state xenon poisoning is not monotonic with respect to gas egress rate, (2) a increase in gas ingress rate leads to a characteristic increase which is followed by a new steady-state in xenon poisoning, and (3) given a sufficient rate of gas egress, it is possible to remove the iodine pit behavior.

Natural Convection With Non-Uniform Heat Generation in Molten Salt Reactor

2009 ◽  
Author(s):  
Libo Qian ◽  
Suizheng Qiu ◽  
Dalin Zhang ◽  
Guanghui Su
Keyword(s):  
Natural Convection ◽  
Rayleigh Number ◽  
Molten Salt ◽  
Heat Generation ◽  
Dimensionless Temperature ◽  
Molten Salt Reactor ◽  
Closed Cavity ◽  
Dimensionless Velocity ◽  
Fuel Salt ◽  
Salt Flow

The Molten Salt Reactor (MSR) is one of the six Generation IV systems capable of breeding and transmutation of actinides and long-lived fission products, which uses the liquid molten salt as the fuel solvent, coolant and heat generation simultaneously. The MSR neutronics, such as the distribution of the delay neutron precursors (DNP), is significantly influenced by the fluid flow, which is quite different from the conventional reactors. Therefore, it is very important to do some research on MSR, especially in accident conditions. The present paper studies the natural convection through which the heat generated by the fuel is removed out of the core region (simply a square cavity in this paper). The neutronic theoretical model is founded based on the conservation law, which consists of two-group neutron diffusion equation for the fast and thermal neutron fluxes and that for one-group DNP, in which the convection terms are included to reflect the fuel salt flow. The SIMPLER numerical method was used to calculate the natural convection heat transfer to the molten salt inside a closed cavity for which the boundary temperature was spatially uniform. The equations were discretized by finite volume method based on collocated grids, in which QUICK defect correction was adopted for the convection terms and the central difference was for the diffusion terms. The discretization equations were calculated by ADI (Alternative Direction Implicit) with block-correction technique. The distributions of the dimensionless temperature, the dimensionless velocity, the fluxes and the DNP in the cavity were obtained. The calculated results showed that: a) the distribution of the DNP was correlated both with that of the fluxes and with the fuel salt flow and when Rayleigh number increased, the latter one was of much more importance; b) the distribution of the local Nusselt number varied with different Rayleigh numbers; c) the distribution of the dimensionless velocity and the dimensionless temperature were also closely related to Rayleigh number; d) the maximum dimensionless temperature decreased as Rayleigh number increases.

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