scholarly journals Sensitivity study of thermal-hydraulic nodalization for MELCOR simulations of severe accidents in a pressurized water reactor

2022 ◽  
Vol 166 ◽  
pp. 108818
Author(s):  
Nan Zhao ◽  
Yangli Chen ◽  
Weimin Ma ◽  
Sevostian Bechta
Keyword(s):  
Sensitivity Study ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor ◽  
Severe Accidents

scholarly journals A nodal sensitivity study of MELCOR simulation for severe accidents in a pressurized water reactor

2021 ◽  
Vol 160 ◽  
pp. 108373
Author(s):  
Nan Zhao ◽  
Yangli Chen ◽  
Weimin Ma ◽  
Sevostian Bechta ◽  
Patrick Isaksson
Keyword(s):  
Sensitivity Study ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor ◽  
Severe Accidents

CFD Analysis of the Coolant Mixing within the Upper Plenum of a Pressurized Water Reactor (PWR)

2013 ◽  
Vol 444-445 ◽  
pp. 411-415 ◽  
Author(s):  
Fu Cheng Zhang ◽  
Shen Gen Tan ◽  
Xun Hao Zheng ◽  
Jun Chen
Keyword(s):  
Temperature Distribution ◽  
Fluid Dynamic ◽  
Characteristic Temperature ◽  
Reactor Core ◽  
Flow Distribution ◽  
Sensitivity Study ◽  
Cfd Model ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor

In this study, a Computational Fluid Dynamic (CFD) model is established to obtain the 3-D flow characteristic, temperature distribution of the pressurized water reactor (PWR) upper plenum and hot-legs. In the CFD model, the flow domain includes the upper plenum, the 61 control rod guide tubes, the 40 support columns, the three hot-legs. The inlet boundary located at the exit of the reactor core and the outlet boundary is set at the hot-leg pipes several meters away from upper plenum. The temperature and flow distribution at the inlet boundary are given by sub-channel codes. The computational mesh used in the present work is polyhedron element and a mesh sensitivity study is performed. The RANS equations for incompressible flow is solved with a Realizable k-ε turbulence model using the commercial CFD code STAR-CCM+. The analysis results show that the flow field of the upper plenum is very complex and the temperature distribution at inlet boundary have significant impact to the coolant mixing in the upper plenum as well as the hot-legs. The detailed coolant mixing patterns are important references to design the reactor core fuel management and the internal structure in upper plenum.

Hydrogen Concentration Measuring System Designed for Severe Accidents in Containment

2017 ◽  
Author(s):  
Sha Luo ◽  
Yunkai Qian ◽  
Mingjun Ren ◽  
Liang Qin ◽  
Xu Wang
Keyword(s):  
Hydrogen Concentration ◽  
Hydrogen Sensor ◽  
Measuring System ◽  
Pressurized Water Reactor ◽  
Hydrogen Sensors ◽  
Pressurized Water ◽  
Measuring Device ◽  
Water Reactor ◽  
Severe Accidents

Extensively released hydrogen due to zirconium-water reaction during severe accidents in containment of pressurized water reactor raises explosion crisis. Since the containment is the last barrier for fatal irradiation species, efficient measures should be implemented to restrain the hydrogen. Hence, hydrogen elimination and monitor devices are wildly applied to address this issue. Detection of hydrogen once has been conducted by a traditional hydrogen concentration measuring system with sampling devices and hydrogen sensors that located outside the containment. This arrangement, however, is a compromise between actual requirements for hydrogen measuring device and absence of favorable hydrogen sensors which could be applied in the harsh environment under severe accidents. Most recently, R&D of hydrogen concentration measuring system with in-situ hydrogen sensor has attracted increasing attention. Mitsubishi Heavy Industries, Ltd is focusing their job on an electrochemical hydrogen sensor based on solid state electrolyte. Besides, AREVA has developed a system depending on thermal conductivity detector associated with catalytic combustion sensor which requires external power supply to heat the assembly. In PERIC, we have developed a hydrogen concentration measuring system with in-situ hydrogen sensor which can be set in accident confident area. The hydrogen sensor is originally based on catalytic recombination of hydrogen and oxygen. Generally, catalyst prepared using noble metals such as platinum and palladium is scientifically loaded in the hydrogen sensor to serve as hydrogen sensitive material. On the event of severe accidents, mixture of hydrogen and air can spontaneously diffuse into the hydrogen sensor, where, part of the mixture is involved in a chemical exothermic reaction on the catalyst to generate water and heat. Generally, an increased concentration of hydrogen will raise relatively higher reaction temperature of the hydrogen sensor. The hydrogen concentration related temperature of the hydrogen sensor is detected using steel armored thermocouple. Besides, environmental temperature and pressure in the containment are also acquired to assist calculation. All the data are transferred to a signal processing cabinet, which, performs the calculation and indication functions using programmable logic controller and digital display device, respectively. There is no organic material, mechanical moving and power consumption part in the hydrogen sensor and thermocouple. The system indicated reliable performance in simulated containment under condition of high temperature, pressure, steam, and etc. The hydrogen concentration measuring system illustrated excellent endurance to poisoning species such as iodine and aerosol. Furthermore, the hydrogen sensor also suggested high resistance to irradiation. The system can survive a severe earthquake, and its seismic certification toward to safety shutdown earthquake is class I. Over 80 systems so far have be applied in pressurized water reactor in China and or Pakistan. The latest model is designed according to requirements of CAP1400.

Investigation on primary side oriented accident management measures in a hypothetical station blackout scenario for a VVER-1000 pressurized water reactor

Kerntechnik ◽  
2010 ◽  
Vol 75 (1-2) ◽  
pp. 12-19 ◽  
Author(s):  
P. Tusheva ◽  
F. Schäfer ◽  
N. Reinke ◽  
E. Altstadt ◽  
U. Rohde ◽  
...  
Keyword(s):  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor ◽  
Management Measures ◽  
Accident Management ◽  
Station Blackout
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