Air Ingress Phenomena in a Depressurization Accident of the Very-High-Temperature Reactor

2008 ◽  
Author(s):  
Tetsuaki Takeda
Keyword(s):  
High Temperature ◽  
Natural Circulation ◽  
Reactor Core ◽  
Fission Products ◽  
Design Criterion ◽  
Very High Temperature Reactor ◽  
High Temperature Reactor ◽  
Air Ingress ◽  
High Degree ◽  
Very High

The inherent properties of the Very-High-Temperature Reactor (VHTR) facilitate the design of the VHTR with high degree of passive safe performances, compared to other type of reactors. However, it is still not clear if the VHTR can maintain a passive safe function during the primary-pipe rupture accident, or what would be a design criterion to guarantee the VHTR with the high degree of passive safe performances during the accident. The primary-pipe rupture accident is one of the most common of accidents related to the basic design regarding the VHTR, which has a potential to cause the destruction of the reactor core by oxidizing in-core graphite structures and to release fission products by oxidizing graphite fuel elements. It is a guillotine type rupture of the double coaxial pipe at the nozzle part connecting to the side or bottom of the reactor pressure vessel, which is a peculiar accident for the VHTR. This study is to investigate the air ingress phenomena and to develop the passive safe technology for the prevention of air ingress and of graphite corrosion. The present paper describes the influences of a localized natural circulation in parallel channels onto the air ingress process during the primary-pipe rupture accident of the VHTR.

Benchmark Efforts to Support Studies of Advanced VHTRs

2008 ◽  
Author(s):  
David E. Ames ◽  
Pavel V. Tsvetkov
Keyword(s):  
High Temperature ◽  
Very High Temperature Reactor ◽  
High Temperature Reactor ◽  
Heterogeneity Effects ◽  
Test Reactor ◽  
High Degree ◽  
Double Heterogeneity ◽  
Initial Process ◽  
Very High ◽  
Single Batch

The Very High Temperature Reactor (VHTR) is the leading candidate for the reactor component of the Next Generation Nuclear Plant (NGNP). This is because the VHTR demonstrates great potential in improving safety characteristics, being economically competitive, providing a high degree of proliferation resistance, and producing high outlet temperatures for efficient electricity generation and/or other high temperature applications, most notably hydrogen production. In addition, different fuel types can be utilized by VHTRs, depending on operational goals. In this case, the recovery and utilization of the valuable energy left in LWR fuel in order to create ultra long life single batch cores by taking advantage of the properties of TRU fuels. This paper documents the initial process in the study of TRU fueled VHTRs, which concentrates on the verification and validation of the developed whole-core 3D VHTR models. Many of the codes used for VHTR analysis were developed without a full appreciation of the importance of randomness in particle distribution. With this in mind, the SCALE code system was chosen as the computational tool for the study. It provides the opportunity of utilizing SCALE versions 5.0 and 5.1, making it possible to compare and analyze different techniques accounting for the double heterogeneity effects associated with VHTRs. Startup physics results for Japan’s High Temperature Test Reactor (HTTR) were used for experiment-to-code benchmarking. MCNP calculations were employed for code-to-code benchmarking. Results and analysis are included in this paper.

scholarly journals Computational Fluid Dynamics Analyses on Very High Temperature Reactor Air Ingress

2009 ◽  
Author(s):  
Chang H. Oh ◽  
Eung S. Kim ◽  
Richard Schultz ◽  
David Petti ◽  
Hyung S. Kang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Temperature ◽  
System Analysis ◽  
Onset Time ◽  
The Core ◽  
Very High Temperature Reactor ◽  
High Temperature Reactor ◽  
Air Ingress ◽  
Very High

A preliminary computational fluid dynamics (CFD) analysis was performed to understand density-gradient-induced stratified flow in a Very High Temperature Reactor (VHTR) air-ingress accident. Various parameters were taken into consideration, including turbulence model, core temperature, initial air mole-fraction, and flow resistance in the core. The gas turbine modular helium reactor (GT-MHR) 600 MWt was selected as the reference reactor and it was simplified to be 2D geometry in modeling. The core and the lower plenum were assumed to be porous bodies. Following the preliminary CFD results, the analysis of the air-ingress accident has been performed by two different codes: GAMMA code (system analysis code, Oh et al. 2006) and FLUENT CFD code (Fluent 2007). Eventually, the analysis results showed that the actual onset time of natural convection (∼160 sec) would be significantly earlier than the previous predictions (∼150 hours) calculated based on the molecular diffusion air-ingress mechanism. This leads to the conclusion that the consequences of this accident will be much more serious than previously expected.

Neutronic design of a very high temperature reactor core with low graphite content

2013 ◽  
Vol 55 ◽  
pp. 71-74 ◽  
Author(s):  
Dionisio Telésforo-Reyes ◽  
Juan-Luis François ◽  
Cecilia Martín-del-Campo ◽  
Arturo G. Reinking-Cejudo
Keyword(s):  
High Temperature ◽  
Reactor Core ◽  
Graphite Content ◽  
Very High Temperature Reactor ◽  
High Temperature Reactor ◽  
Very High
Sign in / Sign up

Export Citation Format

Share Document