scholarly journals Investigation of Control Characteristics for a Molten Salt Reactor Plant under Normal and Accident Conditions

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5279
Author(s):  
Run Luo ◽  
Chunyu Liu ◽  
Rafael Macián-Juan
Keyword(s):  
Control System ◽  
Molten Salt ◽  
Control Strategy ◽  
Liquid Fuel ◽  
Normal Operation ◽  
Temperature Control System ◽  
Molten Salt Reactor ◽  
Carrier Fluid ◽  
Operation Conditions ◽  
Accident Conditions

A molten salt reactor (MSR) has unique safety and economic advantages due to the liquid fluoride salt adopted as the reactor fuel and heat carrier fluid. The operation scheme and control strategy of the MSR plant are significantly different from those of traditional solid-fuel reactors because of the delayed neutron precursors drift with the liquid-fuel flow. In this paper, a simulation platform of the MSR plant is developed to study the control characteristics under normal and accident conditions. A nonlinear dynamic model of the whole system is built in the platform consisting of a liquid-fuel reactor with a graphite moderator, an intermediate heat exchanger and a steam generator. A new control strategy is presented based on a feed-forward and feedback combined scheme, a power control system and a steam temperature control system are designed to regulate load changes of the plant. Three different types of operation conditions are simulated with the control systems, including transients of normal load-follow operation, a reactivity insertion accident and a loss of flow accident. The simulation results show that the developed control system not only has a fast load-follow capability during normal operation, but also has a good control performance under accident conditions.

Feedback Control to Prevent Damage by Rotor Rubbing After an Impact Load

2009 ◽  
Author(s):  
Lucas Ginzinger ◽  
Benjamin Heckmann ◽  
Heinz Ulbrich
Keyword(s):  
Control System ◽  
Feedback Control ◽  
Control Strategy ◽  
Impact Load ◽  
Operation Mode ◽  
Rotor System ◽  
Contact Forces ◽  
Normal Operation ◽  
Control Force ◽  
Auxiliary Bearing

A new approach to control a rubbing rotor by applying an active auxiliary bearing has been developed. The control force is applied indirectly using the auxiliary bearing, only in case of rotor rubbing. The auxiliary bearing is actuated using two unidirectional actuators. A three-phase control strategy has been developed which stabilizes the rotor system in case of an impact load and effectively avoids “backward whirling” which is very destructive. As soon as the load ceased the auxiliary bearing is separated from the rotor again and normal operation mode is continued. During the normal operation state, the feedback control does not interfere with the rotor system at all. A test rig has been developed to experimentally verify the control system. Various experiments show the success of the control strategy. In case of rubbing, the contact forces are reduced up to 95 percent. At the same time, the rotor deflection is decreased too. The activation and deactivation of the control system is operated fully automatically. A simulation framework for an elastic rotor including the non-smooth nonlinear dynamics of contacts is presented, which has been used to develop the feedback controller.

Efficient and Robust Rub Control With an Active Auxiliary Bearing

2007 ◽  
Author(s):  
Lucas Ginzinger ◽  
Heinz Ulbrich
Keyword(s):  
Control System ◽  
Control Strategy ◽  
High Efficiency ◽  
Industrial Applications ◽  
Rotor System ◽  
Contact Forces ◽  
Smooth Transition ◽  
Normal Operation ◽  
Control Force ◽  
Auxiliary Bearing

In this contribution, a new approach to control a rubbing rotor by applying an active auxiliary bearing is presented. The auxiliary bearing is attached to the foundation via two unidirectional actuators. The control force is applied indirectly using the auxiliary bearing, only in case of rotor rubbing. During a normal operation state, the feedback control does not interfere with the rotor system at all. A robust control system has been developed which significantly reduces the intensity of rubbing by stabilizing the rotor system and assuring an optimal rubbing state in case of a too large rotor amplitude. The two-phase control strategy guarantees a smooth transition from free rotor motion to the state of synchronous full annular rub. A test rig has been developed to experimentally verify the control system. Various experiments show the success of the control strategy. In case of rubbing, the contact forces are reduced up to 80 per cent, which results in significantly lower loads. At the same time, the rotor deflection is decreased too. For industrial applications, the activation of the control system can be operated fully automatically. The high efficiency of the control algorithm allows an implementation on microcontrollers. The developed control of the auxiliary bearing reduces the load and the noise of the system during rotor rubbing significantly.

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

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.

Preliminary Study of the Use of Freeze-Valves for a Passive Shutdown System in Molten Salt Reactors

2014 ◽  
Author(s):  
Qiming Li ◽  
Zhongfeng Tang ◽  
Yuan Fu ◽  
Zhong Li ◽  
Naxiu Wang
Keyword(s):  
Molten Salt ◽  
Nuclear Reactor ◽  
Reactor Core ◽  
Mechanical Valve ◽  
Thermal Design ◽  
Normal Operation ◽  
Passive System ◽  
Fuel Salt ◽  
Preliminary Study ◽  
Accident Conditions

The use of passive shutdown systems to enhance safety is one element of next-generation reactor design. The Freeze-Valve has been proposed as a key device in the passive system to stop the chain reaction of the Molten Salt Reactor (MSR), which has been chosen by Generation IV International Forum (GIF) as one of the six Generation IV reactor concepts. During reactor normal operation, the molten salt in the valve is cooled to a solid plug. In the event that the reactor overheats under accident conditions when all other active control systems fail, the plug will melt. The liquid fuel salt will be pulled out from the reactor core by gravity into dump tanks, and criticality will cease because the reaction is no longer moderated by the graphite in the reactor core. The more accurate the Freeze-Valve’s thermal design is, the more efficient the passive shutdown system becomes. In this study, an investigation of the thermal performance of the Freeze-Valve is conducted based on finite element methods verified by experimental data, and some modified designs are presented with recommendations. For further consideration, some innovative governing techniques used to control the Freeze-Valve are discussed in detail. Here, a more critical thermal design is focused on that can make the passive system shut down the nuclear reactor quickly and reliably. The Freeze-Valve can be used in the molten salt loop rather than a mechanical valve, which may become jammed by frozen salt. Paper published with permission.

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

2014 ◽  
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.

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

2020 ◽  
Vol 44 (5) ◽  
pp. 3934-3953
Author(s):  
Yeong Shin Jeong ◽  
Eric Cervi ◽  
Antonio Cammi ◽  
Hisashi Ninokata ◽  
In Cheol Bang
Keyword(s):  
Sensitivity Analysis ◽  
Molten Salt ◽  
Liquid Fuel ◽  
Molten Salt Reactor ◽  
Fuel System

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

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.

scholarly journals PREDICTION OF OPERATION LIFE EXTENSION OF HEAT POWER EQUIPMENT

2020 ◽  
Vol 2 (61) ◽  
pp. 51-60
Author(s):  
V. Skalozubov ◽  
◽  
D. Pirkovsky ◽  
M. Alali ◽  
R. Algerby ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Accumulation Rate ◽  
Reactor Vessel ◽  
Life Extension ◽  
Normal Operation ◽  
Cyclic Loads ◽  
Power Equipment ◽  
Heat Power ◽  
Operation Conditions ◽  
Accident Conditions

Based on the analysis of known researches, it is revealed that the quantity and accumulation rate of cyclic thermal and dynamic loads in the transient modes of normal operation conditions, when violating normal operation conditions and in accident conditions (except for the nuclear reactor vessel) are the key factors of prediction of operation life extension for a heat power equipment (heat exchangers, pumps, armature). The method for predictive estimation of terms of operation life extension of a heat power equipment depending on stress amplitudes in transient and accident conditions, quantity and accumulation rate of cyclic loads, strength metal parameters of a heat power equipment vessels (except for a reactor vessel) is provided. The method is implemented on the example of steam generators of WWERs and using operational data of South-Ukraine-1 (by 2010). Admissible accumulation rate of cyclic loads during operation life extension by 30, 40 and 50 years is a result. The results define insufficient substantiation of nuclear power plant operation in the “maneuverable” modes with a variable reactor power. In this case, the quantity of cyclic equipment loads increases dramatically, and terms of safe operation are limited. The developed method and the obtained results of prediction of operation life extension of heat power equipment can be used for industry programs to extend the operation of Ukrainian nuclear power plants, as well as to improve the regulatory documents governing the conditions and requirements for acceptable safe extension of the operation life of heat power equipment of nuclear and thermal power enterprises. Further improvement of the method proposed in the work for predicting operation life extension of heat power equipment can be based on the development of methods for analyzing the reliability of heat power equipment and databases on operation disturbances.The materials of the presented work are used in the educational process for the training, retraining and advanced training of specialists in the energy industry.

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

2017 ◽  
Vol 42 (1) ◽  
pp. 261-275 ◽  
Author(s):  
Liangzhi Cao ◽  
Kun Zhuang ◽  
Youqi Zheng ◽  
Tianliang Hu ◽  
Hongchun Wu
Keyword(s):  
Molten Salt ◽  
Transient Analysis ◽  
Liquid Fuel ◽  
Molten Salt Reactor
Sign in / Sign up

Export Citation Format

Share Document