The Stimulation of a Tight, Very-High- Temperature Gas-Condensate Well

1989 ◽  
Vol 4 (01) ◽  
pp. 63-72 ◽  
Author(s):  
Michael J. Economides ◽  
Marin Cikes ◽  
Harry Pforter ◽  
Thomas H. Udick ◽  
Pavle Uroda
Keyword(s):  
High Temperature ◽  
Gas Condensate ◽  
Very High ◽  
High Temperature Gas ◽  
Stimulation Of

scholarly journals Conceptual Core Design Study of the Very High Temperature Gas-Cooled Reactor (VHTR) Upgrading the Core Performance by Using Multihole-Type Fuel

2008 ◽  
Vol 7 (1) ◽  
pp. 32-43 ◽  
Author(s):  
Kazutaka OHASHI ◽  
Tetsuo NISHIHARA ◽  
Kazuhiko KUNITOMI ◽  
Masaaki NAKANO ◽  
Yujiro TAZAWA ◽  
...  
Keyword(s):  
High Temperature ◽  
Design Study ◽  
The Core ◽  
Conceptual Core ◽  
Very High ◽  
Type Fuel ◽  
High Temperature Gas

scholarly journals Hydroxyl, water, ammonia, carbon monoxide and neutral carbon towards the Sgr A complex

2013 ◽  
Vol 9 (S303) ◽  
pp. 97-99
Author(s):  
R. Karlsson ◽  
Aa. Sandqvist ◽  
Å. Hjalmarson ◽  
A. Winnberg ◽  
K. Fathi ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
High Temperature ◽  
Open Access ◽  
Gas Phase ◽  
Combined Action ◽  
Circumnuclear Disk ◽  
Sgr A ◽  
Grain Surface ◽  
Very High ◽  
High Temperature Gas

AbstractWe observed Hydroxyl, water, ammonia, carbon monoxide and neutral carbon towards the +50 km s−1 cloud (M−0.02−0.07), the circumnuclear disk (CND) and the +20 km s−1 (M−0.13−0.08) cloud in the Sgr A complex with the VLA, Odin and SEST. Strong OH absorption, H2O emission and absorption lines were seen at all three positions. Strong C18O emissions were seen towards the +50 and +20 km s−1 clouds. The CND is rich in H2O and OH, and these abundances are considerably higher than in the surrounding clouds, indicating that shocks, star formation and clump collisions prevail in those objects. A comparison with the literature reveals that it is likely that PDR chemistry including grain surface reactions, and perhaps also the influences of shocks has led to the observed abundances of the observed molecular species studied here. In the redward high-velocity line wings of both the +50 and +20 km s−1 clouds and the CND, the very high H2O abundances are suggested to be caused by the combined action of shock desorption from icy grain mantles and high-temperature, gas-phase shock chemistry. Only three of the molecules are briefly discussed here. For OH and H2O three of the nine observed positions are shown, while a map of the C18O emission is provided. An extensive paper was recently published with Open Access (Karlsson et al. 2013, A&A 554, A141).

Development of a physics analysis procedure for the prismatic very high temperature gas-cooled reactors

2007 ◽  
Vol 34 (11) ◽  
pp. 849-860 ◽  
Author(s):  
Kang-Seog Kim ◽  
Jin-Young Cho ◽  
Hyun Chul Lee ◽  
Jae Man Noh ◽  
Sung Quun Zee
Keyword(s):  
High Temperature ◽  
Analysis Procedure ◽  
Very High ◽  
High Temperature Gas

scholarly journals Study on Air Ingress Mitigation Methods in the Very High Temperature Gas Cooled Reactor (VHTR)

2011 ◽  
Author(s):  
Chang H. Oh ◽  
Eung S. Kim
Keyword(s):  
High Temperature ◽  
Root Cause ◽  
The Core ◽  
Graphite Oxidation ◽  
Simulation Results ◽  
Oxidation Damage ◽  
Air Ingress ◽  
Mitigation Methods ◽  
Very High ◽  
High Temperature Gas

An air-ingress accident followed by a pipe break is considered as a critical event for a very high temperature gas-cooled reactor (VHTR) safety. Following helium depressurization, it is anticipated that unless countermeasures are taken, air will enter the core through the break leading to oxidation of the in-core graphite structure. Thus, without mitigation features, this accident might lead to severe exothermic chemical reactions of graphite and oxygen depending on the accident scenario and the design. Under extreme circumstances, a loss of core structural integrity may occur along with excessive release of radiological inventory. Idaho National Laboratory under the auspices of the U.S. Department of Energy is performing research and development (R&D) that focuses on key phenomena important during challenging scenarios that may occur in the VHTR. Phenomena Identification and Ranking Table (PIRT) studies to date have identified the air ingress event, following on the heels of a VHTR depressurization, as very important (Oh et al. 2006, Schultz et al. 2006). Consequently, the development of advanced air ingress-related models and verification and validation (V&V) requirements are part of the experimental validation plan. This paper discusses about various air-ingress mitigation concepts applicable for the VHTRs. The study begins with identifying important factors (or phenomena) associated with the air-ingress accident using a root-cause analysis. By preventing main causes of the important events identified in the root-cause diagram, the basic air-ingress mitigation ideas can be conceptually derived. The main concepts include (1) preventing structural degradation of graphite supporters; (2) preventing local stress concentration in the supporter; (3) preventing graphite oxidation; (4) preventing air ingress; (5) preventing density gradient driven flow; (6) preventing fluid density gradient; (7) preventing fluid temperature gradient; (7) preventing high temperature. Based on the basic concepts listed above, various air-ingress mitigation methods are proposed in this study. Among them, the following one mitigation idea was extensively investigated using computational fluid dynamic codes (CFD) in terms of helium injection in the lower plenum. The main idea of the helium injection method is to replace air in the core and the lower plenum upper part by buoyancy force. This method reduces graphite oxidation damage in the severe locations of the reactor inside. To validate this method, CFD simulations are addressed here. A simple 2-D CFD model was developed based on the GT-MHR 600MWt as a reference design. The simulation results showed that the helium replaces the air flow into the core and significantly reduces the air concentration in the core and bottom reflector potentially protecting oxidation damage. According to the simulation results, even small helium flow was sufficient to remove air in the core, mitigating the air-ingress successfully.

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