CFD Analysis of the ESFR Reactor Pit Cooling System in Case of Sodium Leakage

Abstract The Decay Heat Removal System (DHRS) for the ESFR Concept consists of three cooling systems, which provide highly reliable, redundant and diversified decay heat removal function. Two of the systems provide strong line of defense, whereas the third system provides a weak line of defense. This third DHR system, DHRS-3, involves separate oil and water cooling loops integrated in the reactor pit, which is installed instead of the safety vessel. It is hoped that the proposed DHR concept enables a robust demonstration of the practical elimination. For its confirmation, detailed numerical analysis is needed as a basis for further investigation. Supporting this approach, the current CFD computation provides a preliminary thermal analysis of the capability of the oil cooling system in the reactor to be used for residual heat removal pit in case of an emergency. For the evaluation, different heat flux values are assumed at the vessel wall to examine the range of the resulting temperatures. The temperature of the main vessel wall should remain below 800°C. Furthermore, a sodium leakage at 500°C into the reactor pit is assumed. The concrete structure should remain below 70°C.

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Study of the Behaviors of an Open-Loop Heat-Removal System

Volume 6B: Thermal-Hydraulics and Safety Analyses ◽

10.1115/icone26-82146 ◽

2018 ◽

Author(s):

Xianmao Wang ◽

Yonggang Shen ◽

Jiang Yang ◽

Yong Ouyang ◽

Min Rui ◽

...

Keyword(s):

Cooling System ◽

Natural Circulation ◽

Heat Removal ◽

Calculation Model ◽

Open Loop ◽

Cooling Systems ◽

Core Cooling ◽

Passive Cooling Systems ◽

Heat Removal System ◽

Removal System

In the third generation of nuclear reactors, passive systems have been widely used such as passive core cooling system and passive containment cooling system, which usually relay on natural circulation induced by buoyancy force to remove heat. Most of these passive cooling systems are closed-loop natural circulations. In recent years, some open-loop heat-removal systems have also been put forward. Open-loop heat-removal systems have its own advantages such as its simplification and low costs. However, the thermal-hydraulic behaviors of open-loop heat-removal systems are still not totally clear and need further study. In this study, a simplified open-loop passive containment cooling system is studied. A calculation model is built based on RELAP SCDAPSIM code. The thermal-hydraulic behaviors of the system are studied. By changing some key parameters of the system, the influences of these parameters on the system are evaluated.

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Transient Analyses of Passive Residual Heat Removal System of 10MW Molten Salt Reactor Experiment

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.953-954.621 ◽

2014 ◽

Vol 953-954 ◽

pp. 621-626

Author(s):

Hang Bin Zhao ◽

Chang Qi Yan ◽

Li Cheng Sun ◽

Kai Bin Zhao

Keyword(s):

Molten Salt ◽

Power Plants ◽

Heat Removal ◽

Molten Salt Reactor ◽

Inherent Safety ◽

Decay Heat ◽

Reactor Experiment ◽

Heat Removal System ◽

Removal System ◽

Residual Heat

In order to improve the inherent safety of the Molten Salt Reactor (MSR), a concept of passive residual heat removal system (PRHRS) for the 10MW Molten Salt Reactor Experiment (MSRE) was put forward. Its transient characteristics were investigated by developing a model of it using C++ code. The effects of environmental temperature, finned tube number and chimney height on the PRHRS were analyzed. The results show that the PRHRS can remove the decay heat timely. Three natural circulations are established in the PRHRS when it begins to operate. With the decay heat power reducing, the PRHRS can automatically adjust its heat removal ability. It needs not any external power for the PRHRS to operate, which enhances the inherent safety and reliability of the reactor, especially under the condition that power plants lose power.

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Performance Evaluation of SCS for AHTR and Time Assessment of Operation Procedures

Volume 5: Innovative Nuclear Power Plant Design and New Technology Application; Student Paper Competition ◽

10.1115/icone22-30790 ◽

2014 ◽

Author(s):

Takahito Ogura ◽

Junya Nakata ◽

Mititsugu Mori ◽

Hiroto Sakashita ◽

Shuichiro Miwa

Keyword(s):

Melting Point ◽

Cooling System ◽

Heat Removal ◽

The United States ◽

Important Conclusion ◽

Cooling Period ◽

Decay Heat ◽

Temperature Distributions ◽

Heat Removal System ◽

Removal System

The Advanced High-Temperature Reactor (AHTR) is a new nuclear power reactor concept being investigated in some countries including the United States. The coolant is a liquid salt with a melting point of 460°C and a boiling point of 1430°C. The AHTR uses Silo Cooling System (SCS) as the decay heat removal system in a Beyond-Design-Basis Accident (BDBA). SCS has two accident mitigations. The first component is low-cost, and thick steel rings which conduct heating up the silo wall for BDBA. The second component is an annular ring of an inexpensive, solidified BDBA salt, which is heated from the bottom and melts when the temperature of the salt increases above the melting point, then flows into the silo, and floods the whole silo to its top level. SCS could make AHTR free from catastrophic accidents, where core melting or vessel failure never takes place since the BDBA salt near the top of silo passively absorbs decay heat. On the other hand, AHTR decreases its heat removal ability to avoid freezing of the salt and blocking the flow of the liquid when the temperatures are low. We performed the numerical calculation of AHTR heat removal system and evaluated whether it has the ability to remove decay heat with the robustness for a long-time cooling operation after BDBA. Furthermore, we need to build up and optimize the operation plan of SCS in AHTR, taking its thermal characteristics of this system into account. It is essential to avoid severe accidents which we can suppose as the possible catastrophic scenario. In this paper, we calculated temperature distributions using the thermal-hydraulics code developed for AHTR, and assessed the performance in a long term cooling period under BDBA conditions. Finally, we investigated the temperature distributions of the whole plant, predicting the accident scenario without air-cooled passive decay heat-removal system. We obtained important conclusion about SCS of the AHTR that its heat removal ability was enough to avoid catastrophic accidents under Loss of Heat Sink (LOHS) conditions.

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Analysis on passive residual heat removal system with heat pipes for longterm decay heat removal of small lead-based reactor

E3S Web of Conferences ◽

10.1051/e3sconf/202123601018 ◽

2021 ◽

Vol 236 ◽

pp. 01018

Author(s):

Chongju Hu ◽

Wangli Huang ◽

Zhizhong Jiang ◽

Qunying Huang ◽

Yunqing Bai ◽

...

Keyword(s):

Three Dimensional ◽

Heat Removal ◽

Heat Pipes ◽

Decay Heat ◽

The Core ◽

Accident Condition ◽

Computational Fluid Dynamics Cfd ◽

Heat Removal System ◽

Removal System ◽

Residual Heat

.A lead-based reactor with employing heat pipes as passive residual heat removal system (PRHRS) for longterm decay heat removal was designed. Three-dimensional computational fluid dynamics (CFD) software FLUENT was adopted to simulate the thermal-hydraulic characteristics of the PRHRS under Station-Black-Out (SBO) accident condition. The results showed that heat in the core could be removed smoothly by the PRHRS, and the core temperature difference is less than 20 K.

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