Adjoint‐based sensitivity analysis of circulating liquid fuel system for the multiphysics model of molten salt reactor

Molten salt reactor is the only one of the liquid fuel reactors in the fourth generation reactors. The flow characteristics of the fluoride makes differences between the liquid fuel reactor and the solid fuel reactor. For licensing of novel design of molten salt reactor, the peak temperature of the molten salt in primary loop has significant influence on the reactor safety. Sensitivity analysis for the peak temperature during pump coast down accident is performed by coupling Dakota and Genflow code. Dakota is a multilevel parallel object-oriented framework for design optimization, parameter estimation, uncertainty quantification, and sensitivity analysis. Dakota generate a plurality of parameters of input files, can greatly simplify the manual optimization process, it will reduce a lot of uncertainty analysis time. GenFlow develop the technical basis for design and licensing of fluoride-salt-cooled, high-temperature reactors, simulate the accident condition and export the instantaneous state. The work coupled Dakota and GenFlow to do the uncertainty analysis, the experience also have important inspiration and reference to coupling Dakota with other code. The work aims at the scenario when the pump coast down and the natural circulation is established. Five key thermal parameters, namely the power load factor, coast down time, the check valve open time, total form losses in the DRACS loop, total form losses in the DHX branch, that affect the natural circulation in the molten salt reactor is sampled within a certain range using the LHS (Latin hypercube sampling) method. The Dakota generate multiple parameters of the input card that are run by GenFlow code automatically. The post-processing results turn back to Dakota to do the uncertainty analysis and sensitivity analysis, which greatly simplify the optimization process and do not need exact mathematical model. It shows the correlativity about the peak temperature with every parameters and the influence between the parameters. Statistical results showed that the effect of the power load factor on peak temperature is very significant, followed by the DHX shell side. After the moment-related statistics, the 95% confidence intervals on the mean and standard deviations are printed. There are 95% confident that the true value of the parameter is in confidence interval between 809.547 and 816.3227. In this sample, 15% of the actual calculation results is higher than the critical point 816°C.

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A Novel Molten Salt Reactor Concept to Implement the Multi-Step Time-Scheduled Transmutation Strategy

10th International Conference on Nuclear Engineering, Volume 4 ◽

10.1115/icone10-22688 ◽

2002 ◽

Author(s):

Gyula Csom ◽

Sandor Feher ◽

Mate Szieberth

Keyword(s):

Molten Salt ◽

Liquid Fuel ◽

Primary Circuit ◽

Chemical Processing ◽

Molten Salt Reactor ◽

The Core ◽

Continuous Feed ◽

Fuel Mixtures ◽

Continuous Chemical ◽

Optimal Implementation

Nowadays the molten salt reactor (MSR) concept seems to revive as one of the most promising systems for the realization of transmutation. In the molten salt reactors and subcritical systems the fuel and material to be transmuted circulate dissolved in some molten salt. The main advantage of this reactor type is the possibility of the continuous feed and reprocessing of the fuel. In the present paper a novel molten salt reactor concept is introduced and its transmutational capabilities are studied. The goal is the development of a transmutational technique along with a device implementing it, which yield higher transmutational efficiencies than that of the known procedures and thus results in radioactive waste whose load on the environment is reduced both in magnitude and time length. The procedure is the multi-step time-scheduled transmutation, in which transformation is done in several consecutive steps of different neutron flux and spectrum. In the new MSR concept, named “multi-region” MSR (MRMSR), the primary circuit is made up of a few separate loops, in which salt-fuel mixtures of different compositions are circulated. The loop sections constituting the core region are only neutronically and thermally coupled. This new concept makes possible the utilization of the spatial dependence of spectrum as well as the advantageous features of liquid fuel such as the possibility of continuous chemical processing etc. In order to compare a “conventional” MSR and a proposed MRMSR in terms of efficiency, preliminary calculational results are shown. Further calculations in order to find the optimal implementation of this new concept and to emphasize its other advantageous features are going on.

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Development and Verification of Dynamics Code for Molten Salt Reactors

12th International Conference on Nuclear Engineering, Volume 1 ◽

10.1115/icone12-49130 ◽

2004 ◽

Cited By ~ 2

Author(s):

Jiri Krepel ◽

Ulrich Grundmann ◽

Ulrich Rohde

Keyword(s):

Molten Salt ◽

Liquid Fuel ◽

Expansion Method ◽

Primary Circuit ◽

Fuel System ◽

Delayed Neutrons ◽

Flow Acceleration ◽

Fuel Flow ◽

Reactor Dynamics ◽

Reactivity Increase

To perform transient analysis for Molten Salt Reactors (MSR), the reactor dynamics code DYN3D developed in FZR was modified for MSR applications. The MSR as a liquid fuel system can serve as a thorium breeder and also as an actinide burner. The specifics of the reactor dynamics of MSR consist in the fact, that there is direct influence of the fuel velocity to the reactivity, which is caused by the delayed neutrons precursors drift. This drift causes the spread of delayed neutrons distribution to the non-core parts of primary circuit. This leads to a reactivity loss due to the fuel flow acceleration or to the reactivity increase in the case of deceleration. For the first analyses, a 1D modified version DYN1D-MSR of the code has been developed. By means of the DYN1D-MSR, several transients typical for the liquid fuel system were analyzed. Transients due to the overcooling of fuel at the core inlet, due to the reactivity insertion, and the fuel pump trip have been considered. The results of all transient studies have shown that the dynamic behavior of MSR is stable when the coefficients of thermal feedback are negative. For studying space-dependent effects like e.g. local blockages of fuel channels, a 3D code version DYN3D-MSR will be developed. The nodal expansion method used in DYN3D for hexagonal fuel element geometry of VVER can be applied considering MSR design with hexagonal graphite channels.

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COUPLE, A Time-Dependent Coupled Neutronics and Thermal-Hydraulics Code, and its Application to MSFR

Volume 3: Next Generation Reactors and Advanced Reactors; Nuclear Safety and Security ◽

10.1115/icone22-30609 ◽

2014 ◽

Cited By ~ 1

Author(s):

Dalin Zhang ◽

Zhi-Gang Zhai ◽

Andrei Rineiski ◽

Zhangpeng Guo ◽

Chenglong Wang ◽

...

Keyword(s):

Molten Salt ◽

Liquid Fuel ◽

Time Dependent ◽

Molten Salt Reactor ◽

Thermal Hydraulics ◽

Delayed Neutron ◽

Fuel Flow ◽

Reactor Optimization ◽

Fuel Characteristics ◽

Significant Attention

Molten salt reactor (MSR) using liquid fuel is one of the Generation-IV candidate reactors. Its liquid fuel characteristics are fundamentally different from those of the conventional solid-fuel reactors, especially the much stronger neutronics and thermal hydraulics coupling is drawing significant attention. In this study, the fundamental thermal hydraulic model, neutronic model, and some auxiliary models were established for the liquid-fuel reactors, and a time-dependent coupled neutronics and thermal hydraulics code named COUPLE was developed to solve the mathematic models by the numerical method. After the code was verified, it was applied to the molten salt fast reactor (MSFR) to perform the steady state calculation. The distributions of the neutron fluxes, delayed neutron precursors, velocity, and temperature were obtained and presented. The results show that the liquid fuel flow affects the delayed neutron precursors significantly, while slightly influences the neutron fluxes. The flow in the MSFR core generates a vortex near the fertile tank, which leads to the maximal temperature about 1100 K at the centre of the vortex. The results can provide some useful information for the reactor optimization.

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Effect of FLiBe thermal neutron scattering on reactivity of molten salt reactor

EPJ Web of Conferences ◽

10.1051/epjconf/202023914008 ◽

2020 ◽

Vol 239 ◽

pp. 14008

Author(s):

Yafen Liu ◽

Wenjiang Li ◽

Rui Yan ◽

Yang Zou ◽

Shihe Yu ◽

...

Keyword(s):

Neutron Scattering ◽

Thermal Neutron ◽

Molten Salt ◽

Liquid Fuel ◽

Volume Ratio ◽

Scattering Data ◽

Maximum Effect ◽

Molten Salt Reactor ◽

Thermal Neutron Scattering ◽

Thorium Molten Salt Reactor

Thermal neutron scattering data has an important influence on the calculation and design of reactor with a thermal spectrum. However, as the only liquid fuel in the Gen-IV reactor candidates, the research on the thermal neutron scattering effect of coolant and somewhat moderator FLiBe has not been carried out sufficiently either experimentally or theoretically. The effect of FLiBe thermal neutron scattering on reactivity of TMSR-LF (thorium molten salt reactor - liquid fuel), TMSR-SF (thorium molten salt reactor - solid fuel) and MSRE (molten salt reactor experiment) were investigated and compared. Results show that the effect of FLiBe thermal neutron scattering on reactivity depends to some extent on the fuel-graphite volume ratio of core. Calculations indicate that FLiBe thermal neutron scattering of MSRE (with the hardest spectrum) has the minimum effect of 41 pcm on reactivity, and FLiBe thermal neutron scattering of TMSR-SF (with the softest spectrum) has the maximum effect of -94 pcm on reactivity, and FLiBe thermal neutron scattering of TMSR-LF has an effect of -61 pcm on reactivity at 900 K.

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Transient analysis for liquid-fuel molten salt reactor based on MOREL2.0 code

International Journal of Energy Research ◽

10.1002/er.3828 ◽

2017 ◽

Vol 42 (1) ◽

pp. 261-275 ◽

Cited By ~ 4

Author(s):

Liangzhi Cao ◽

Kun Zhuang ◽

Youqi Zheng ◽

Tianliang Hu ◽

Hongchun Wu

Keyword(s):

Molten Salt ◽

Transient Analysis ◽

Liquid Fuel ◽

Molten Salt Reactor

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Breeding Properties Study on High Power Thorium Molten Salt Reactor

Volume 5: Advanced and Next Generation Reactors, Fusion Technology; Codes, Standards, Conformity Assessment, Licensing, and Regulatory Issues ◽

10.1115/icone25-66961 ◽

2017 ◽

Author(s):

Yafen Liu ◽

Rui Guo ◽

Xiangzhou Cai ◽

Rui Yan ◽

Yang Zou ◽

...

Keyword(s):

Molten Salt ◽

High Power ◽

Liquid Fuel ◽

Molten Salt Reactor ◽

The Core ◽

Optimized Model ◽

Core Conditions ◽

Thorium Molten Salt Reactor ◽

Reactivity Insertion ◽

Two Fluid

The Molten Salt Reactor (MSR), the only one using liquid fuel in the six types ‘Generation IV’ reactors, is very different from reactors in operation now and has initiated very extensive interests all over the world. This paper is primarily aimed at investigating the breeding characteristics of high power (1000 MWe) Thorium Molten Salt Reactor (TMSR) based on the two-fluid Molten Salt Breeder Reactor (MSBR) with superior breeding performance. We explored the optimized structure to be a thorium based molten salt breeder reactor with different core conditions and different post-processing programs, and finally got the breeding ratio of 1.065 in our TMSR model. At last we analyzed the transient security of our optimized model with results show that the temperature coefficient of core is −3 pcm/K and a 2000 pcm reactivity insertion can be successfully absorbed by the core if the insertion time is more than or equal to 5 seconds and the core behaves safely.

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Breeding Properties Study on High-Power Thorium Molten Salt Reactor

Journal of Nuclear Engineering and Radiation Science ◽

10.1115/1.4041272 ◽

2019 ◽

Vol 5 (1) ◽

Cited By ~ 1

Author(s):

Yafen Liu ◽

Rui Guo ◽

Xiangzhou Cai ◽

Rui Yan ◽

Yang Zou ◽

...

Keyword(s):

Molten Salt ◽

High Power ◽

Liquid Fuel ◽

Molten Salt Reactor ◽

The Core ◽

Optimized Model ◽

Core Conditions ◽

Thorium Molten Salt Reactor ◽

Reactivity Insertion ◽

Two Fluid

Molten salt reactor (MSR), the only one using liquid fuel in the six types “Generation IV” reactors, is very different from reactors in operation now and has initiated very extensive interests all over the world. This paper is primarily aimed at investigating the breeding characteristics of high-power thorium molten salt reactor (TMSR) based on the two-fluid molten salt breeder reactor (MSBR) with a superior breeding performance. We explored the optimized structure to be a thorium-based molten salt breeder reactor with different core conditions and different postprocessing programs, and finally got the breeding ratio of 1.065 in our TMSR model. At last we analyzed the transient security of our optimized model with results show that the temperature coefficient of core is −3 pcm/K and a 2000 pcm reactivity insertion can be successfully absorbed by the core if the insertion time is more than or equal to 5 s and the core behaves safely.

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