Experimental and modelling results of the QUENCH-18 bundle experiment on air ingress, cladding melting and aerosol release

2021 ◽  
Vol 379 ◽  
pp. 111267
Author(s):  
Juri Stuckert ◽  
Martin Steinbrueck ◽  
Jarmo Kalilainen ◽  
Terttaliisa Lind ◽  
Jonathan Birchley
Keyword(s):  
Air Ingress

Managing total reduced sulfur emissions at a Canadian kraft pulp mill

TAPPI Journal ◽  
2016 ◽  
Vol 15 (4) ◽  
pp. 265-272 ◽  
Author(s):  
ROHAN BANDEKAR ◽  
JIM FREDERICK ◽  
JAROSLAV STAVIK
Keyword(s):  
Direct Contact ◽  
Black Liquor ◽  
Pulp Mill ◽  
Packed Bed ◽  
Average Value ◽  
Emission Limit ◽  
Total Reduced Sulfur ◽  
Reduced Sulfur ◽  
Air Ingress ◽  
Solids Content

This study addresses the challenges a dissolving-grade pulp mill in Canada faced in 2014 in meeting its total reduced sulfur (TRS) gas emission limit. These emissions from the recovery boiler exit are controlled by passing the boiler exit gas through a TRS scrubber system. The mill employs a cyclonic direct contact evaporator to concentrate black liquor to firing solids content. The off-gases from the direct contact evaporator flow to the effluent gas control system that consists of a venturi scrubber, a packed bed scrubber, and a heat recovery unit. Emissions of TRS greater than the regulated limit of 15 ppm were observed for a 4-month period in 2014. The level of emissions measured during this period was significantly higher than about 12 ppm, the expected average value based on historic experience. The problem persisted from mid-June 2014 until the annual mill shutdown in October 2014. The main TRS components detected and the performance of the Teller scrubber in capturing them are examined. Other potential causes for these emissions are identified, including mechanical problems such as broken packing in the TRS packed bed scrubber, broken baffle plates in the scrubber, and cyclone evaporator leaks causing air ingress. Repairs were carried out during the mill shutdown, which eliminated the TRS emissions problem.

Numerical analysis of supersonic jet flow and dust transport induced by air ingress in a fusion reactor

2021 ◽  
Vol 32 (7) ◽  
Author(s):  
Bu-Er Wang ◽  
Shi-Chao Zhang ◽  
Zhen Wang ◽  
Jiang-Tao Jia ◽  
Zhi-Bin Chen
Keyword(s):  
Numerical Analysis ◽  
Fusion Reactor ◽  
Supersonic Jet ◽  
Jet Flow ◽  
Dust Transport ◽  
Air Ingress

Investigation of Quench-16 Experiment With MELCOR Computer Code

2014 ◽  
Author(s):  
Petya Vryashkova ◽  
Pavlin Groudev ◽  
Antoaneta Stefanova
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Initial Temperature ◽  
Computer Code ◽  
Air Flow Rate ◽  
Fuel Rod ◽  
Fuel Bundle ◽  
Oxygen Starvation ◽  
Air Ingress ◽  
Good Agreement

This paper presents a comparison of MELCOR calculated results with experimental data for the QUENCH-16 experiment. The analysis for the air ingress experiment QUENCH-16 has been performed by INRNE. The calculations have been performed with MELCOR code. The QUENCH-16 experiment has been performed on 27-th of July 2011 in the frame of the EC-supported LACOMECO program. The experiments have focused on air ingress investigation into an overheated core following earlier partial oxidation in steam. QUENCH-16 has been performed with limited pre-oxidation and low air flow rate. One of the main objectives of QUENCH-16 was to examine the interaction between nitrogen and oxidized cladding during a prolonged period of oxygen starvation. The bundle is made from 20 heated fuel rod simulators arranged in two concentric rings and one unheated central fuel rod simulator, each about 2.5 m long. The tungsten heaters were surrounded by annular ZrO2 pellets to simulate the UO2 fuel. The geometry and most other bundle components are prototypical for Western-type PWRs. To improve the obtained results it has been made a series of calculations to select an appropriate initial temperature of the oxidation of the fuel bundle and modified correlation oxidation of Zircaloy with MELCOR computer code. The compared results have shown good agreement of calculated hydrogen and oxygen starvation in comparison with test data.

Application of Advanced Model of Zr-Based Cladding Oxidation in Steam-Oxygen-Nitrogen Gas Mixtures to Separate Effects Tests and Integral Experiments

2015 ◽  
Author(s):  
Alexander Vasiliev
Keyword(s):  
Diffusion Coefficient ◽  
Nuclear Power ◽  
Temperature Oxidation ◽  
Parabolic Kinetics ◽  
Design Basis ◽  
Design Basis Accident ◽  
Air Ingress ◽  
Pure Steam ◽  
Modeling Code ◽  
Advanced Model

During postulated design-basis or beyond-design-basis accident at nuclear power plant with PWR or BWR, the high temperature oxidation of Zr-based fuel claddings in H2O-O2-N2 gas atmosphere could take place. Recent experimental observations showed that the oxidation of those claddings in the air (or, more generally, in oxygen-nitrogen and steam-nitrogen mixtures) behaves in much more aggressive way (linear or enhanced parabolic kinetics) compared to oxidation in pure steam (standard parabolic kinetics). This is why an advanced model of Zr-based cladding oxidation was developed. For calculations of cladding oxidation in oxygen-nitrogen and steam-nitrogen mixtures, the effective oxygen diffusion coefficient in ZrO2+ZrN layer formed in cladding is used. The diffusion coefficient enhancement factor depends on ZrN content in ZrO2+ZrN layer. A numerical scheme was realized to determine ZrO2+ZrN/α-Zr(O) and α-Zr(O)/β-Zr layers boundaries relocation and layers transformations in claddings. The model was implemented to the SOCRAT best estimate computer modeling code. The SOCRAT code with advanced model of oxidation was successfully used for calculations of separate effects tests and air ingress integral experiments QUENCH-10, QUENCH-16 and PARAMETER-SF4.

Experimental and Numerical Analysis of Mixing Process of Two Component Gases in a Vertical Fluid Layer in a VHTR

2019 ◽  
Vol 5 (2) ◽  
Author(s):  
Tetsuaki Takeda
Keyword(s):  
High Temperature ◽  
Natural Convection ◽  
Numerical Analysis ◽  
Pressure Vessel ◽  
Storage Tank ◽  
Molecular Diffusion ◽  
Flow Characteristics ◽  
Mixing Process ◽  
Two Component ◽  
Air Ingress

When a depressurization accident of a very-high-temperature reactor (VHTR) occurs, air is expected to enter into the reactor pressure vessel from the breach and oxidize in-core graphite structures. Therefore, in order to predict or analyze the air ingress phenomena during a depressurization accident, it is important to develop a method for the prevention of air ingress during an accident. In particular, it is also important to examine the influence of localized natural convection and molecular diffusion on the mixing process from a safety viewpoint. Experiment and numerical analysis using a three-dimensional (3D) computational fluid dynamics code have been carried out to obtain the mixing process of two-component gases and the flow characteristics of localized natural convection. The numerical model consists of a storage tank and a reverse U-shaped vertical rectangular passage. One sidewall of the high-temperature side vertical passage is heated, and the other sidewall is cooled. The low-temperature vertical passage is cooled by ambient air. The storage tank is filled with heavy gas and the reverse U-shaped vertical passage is filled with a light gas. The result obtained from the 3D numerical analysis was in agreement with the experimental result quantitatively. The two component gases were mixed via molecular diffusion and natural convection. After some time elapsed, natural circulation occurred through the reverse U-shaped vertical passage. These flow characteristics are the same as those of phenomena generated in the passage between a permanent reflector and a pressure vessel wall of the VHTR.

scholarly journals Isothermal Air-Ingress Validation Experiments

2013 ◽  
Vol 181 (1) ◽  
pp. 68-80
Author(s):  
Chang H. Oh ◽  
Eung Soo Kim
Keyword(s):  
Air Ingress ◽  
Validation Experiments

Mixing Process of Two Component Gases by Natural Convection and Molecular Diffusion

2021 ◽  
Author(s):  
Takeaki Ube ◽  
Tetsuaki Takeda
Keyword(s):  
High Temperature ◽  
Natural Convection ◽  
Molecular Diffusion ◽  
Natural Circulation ◽  
Mixing Process ◽  
Circulation Flow ◽  
Experimental Apparatus ◽  
Two Component ◽  
High Temperature Reactor ◽  
Air Ingress

Abstract A depressurization accident involving the rupture of the primary cooling pipe of the Gas Turbine High Temperature Reactor 300 cogeneration (GTHTR300C), which is a very-high-temperature reactor, is a design-based accident. When the primary pipe connected horizontally to the side of the reactor pressure vessel of GTHTR300C ruptures, molecular diffusion and local natural convection facilitate gas mixing, in addition to air ingress by counter flow. Furthermore, it is expected that a natural circulation flow around the furnace will suddenly occur. To improve the safety of GTHTR300C, an experiment was conducted using an experimental apparatus simulating the flow path configuration of GTHTR300C to investigate the mixing process of a two-component gas of helium and air. The experimental apparatus consisted of a coaxial double cylinder and a coaxial horizontal double pipe. Ball valves were connected to a horizontal inner pipe and outer pipe, and the valves were opened to simulate damage to the main pipe. As a result, it was confirmed that a stable air and helium density stratification formed in the experimental apparatus, and then a natural circulation flow was generated around the inside of the reactor.

scholarly journals Evaluation of Oxidation Performance of TRISO Fuel Particles for Postulated Air-Ingress Accident of HTGR

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Fangcheng Cao ◽  
De Zhang ◽  
Qingjie Chen ◽  
Hao Li ◽  
Hongqing Wang
Keyword(s):  
Reaction Rates ◽  
Good Oxidation Resistance ◽  
Triso Fuel ◽  
Rate Determining Step ◽  
Parabolic Law ◽  
Oxidation Performance ◽  
Triso Particles ◽  
Fuel Particles ◽  
Air Ingress ◽  
High Temperature Gas

In a high-temperature gas-cooled reactor, the integrity of tristructural-isotropic-(TRISO-) coated fuel particles ensures the safety of the reactor, especially in case of an air-ingress accident. The oxidation of TRISO particles with the outer layers of silicon carbide (SiC) was performed at temperatures of 900°C–1400°C in air environment. Both the microstructure and phase composition of the SiC layers were studied. The results showed that the SiC layers had a good oxidation resistance below 1100°C. However, the amorphous silica on the SiC layers formed at 1200°C and gradually crystallized at 1400°C with the presence of microcracks. The reaction rates of the SiC layers were determined by measuring the silica thickness. It was proposed that the oxidation of the SiC layers followed the linear-parabolic law with the activation energy of 146 ± 5 kJ/mol. The rate-determining step of the oxidation was the diffusion of oxygen in silica.

SARNET2 benchmark on air ingress experiments QUENCH-10, -16

2014 ◽  
Vol 74 ◽  
pp. 12-23 ◽  
Author(s):  
Leticia Fernandez-Moguel ◽  
Christine Bals ◽  
Emilie Beuzet ◽  
Christian Bratfisch ◽  
Olivia Coindreau ◽  
...  
Keyword(s):  
Air Ingress
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