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.

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.

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

Comparative Study of Basic Reactor Physics of the DFR Concept Using U-Pu and TRU Fuel Salts

2017 ◽  
Author(s):  
Xiang Wang ◽  
Rafael Macian-Juan
Keyword(s):  
Steady State ◽  
Liquid Metal ◽  
Molten Salt ◽  
Fast Reactor ◽  
Flux Distribution ◽  
Molten Salt Reactor ◽  
Reactor Physics ◽  
Fuel Salt ◽  
Gen Iv ◽  
First Time

The Dual Fluid Reactor (DFR) is a molten salt fast reactor developed by the IFK1 based on the Gen-IV Molten-Salt Reactor (MSR) and the Liquid-Metal Cooled Reactor (SFR, LFR) concepts. The analysis reported focuses on the comparison between previous neutronic calculations with the default fuel salt of U-Pu mixture and new ones with a transuranium (TRU) salt fuel option under steady state conditions. They include criticality, neutron spectrum, spatial flux distribution and temperature coefficient values. Fuel based on molten TRU salts has already been considered for the MSFR and other molten salt reactor designs. Therefore, the DFR for the first time has a comparable baseline with other molten salt reactors, so that its performance with TRU salt fuel can be assessed.

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.

Study on the Coupled Neutronic and Thermal-Hydraulic Characteristics of the New Concept Molten Salt Reactor

2010 ◽  
Vol 132 (10) ◽  
Author(s):  
Peng Wang ◽  
Libo Qian ◽  
Dalin Zhang ◽  
Wenxi Tian ◽  
Guanghui Su ◽  
...  
Keyword(s):  
Molten Salt ◽  
Flow Velocity ◽  
Design Theory ◽  
Primary Circuit ◽  
Molten Salt Reactor ◽  
Hydraulic Characteristics ◽  
Delayed Neutron ◽  
Flow Effect ◽  
Fuel Reactor ◽  
Fuel Salt

The new concept molten salt reactor is the only liquid-fuel reactor of the six Generation IV advanced nuclear energy systems. The liquid molten salt serves as the fuel and coolant simultaneously and causes one important feature: the delayed neutron precursors are drifted by the fuel flow, which leads the spread of delayed neutrons’ distribution to noncore parts of the primary circuit, and it also results in reactivity variation depending on the flow condition of the fuel salt. Therefore, the neutronic and thermal-hydraulic characteristics of the molten salt reactor are quite different from the conventional nuclear reactors using solid fissile materials. Besides, there is no other reactor design theory and safety analysis methodologies can be used for reference. The neutronic model is derived based on the conservation of particles considering the flow effect of the fuel salt in the molten salt reactor, while the thermal-hydraulic model applies the fundamental conservation laws: the mass, momentum, and energy conservation equations. Then, the neutronic and thermal-hydraulic calculations are coupled and the influences of inflow temperature and flow velocity on the reactor physical properties are obtained. The calculated results show that the flow effect on the distributions of thermal and fast neutron fluxes is very weak, as well as on the effective multiplication factor keff, while the flow effect on the distribution of delayed neutron precursors is much stronger. The inflow temperature influences the distribution of neutron fluxes and delayed neutron precursors slightly, and makes a significant negative reactivity. Coupled calculation also reveals that the flow velocity of molten salt has little effect on the distribution of neutron fluxes in the steady-state, but affects the delayed neutron precursors’ distribution significantly.

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.

A new method for monitoring the redox potential of fuel salt based on the deposition of 95Nb on Hastelloy C276

2021 ◽  
Vol 109 (5) ◽  
pp. 357-365
Author(s):  
Zhiqiang Cheng ◽  
Zhongqi Zhao ◽  
Junxia Geng ◽  
Xiaohe Wang ◽  
Jifeng Hu ◽  
...  
Keyword(s):  
Redox Potential ◽  
Molten Salt ◽  
Specific Activity ◽  
Chemical Reduction ◽  
Quantitative Approach ◽  
Experimental Results ◽  
New Method ◽  
Molten Salt Reactor ◽  
Fuel Salt ◽  
Well Correlation

Abstract To develop the application of 95Nb as an indicator of redox potential for fuel salt in molten salt reactor (MSR), the specific activity of 95Nb in FLiBe salt and its deposition of 95Nb on Hastelloy C276 have been studied. Experimental results indicated that the amount of 95Nb deposited on Hastelloy C276 resulted from its chemical reduction exhibited a positive correlation with the decrease of 95Nb activity in FLiBe salt and the relative deposition coefficient of 95Nb to 103Ru appeared a well correlation with 95Nb activity in FLiBe salt. Both correlations implied that the measurement of 95Nb activity deposited on Hastelloy C276 specimen might provide a quantitative approach for monitoring the redox potential of fuel salt in MSR.

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