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in subjects: "Depressurization"

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Loss-of-coolant accident analyses of the Advanced Neutron Source Reactor

Currently in the conceptual design stage, the Advanced Neutron Source Reactor (ANSR) will operate at a high heat flux, a high mass flux, an a high degree of coolant subcooling. Loss-of-coolant accident (LOCA) analyses using RELAP5 have been performed as part of an early evaluation of ANSR safety issues. This paper discusses the RELAP5 ANSR conceptual design system model and preliminary LOCA simulation results. Some previous studies were conducted for the preconceptual design. 12 refs., 7 figs.

Date: January 1, 1991

Creator: Chen, N.C.J.; Yoder, G.L. (Oak Ridge National Lab., TN (USA)) & Wendel, M.W. (Martin Marietta Energy Systems, Inc., Oak Ridge, TN (USA))

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Large break loss-of-coolant accident analyses for the high flux isotope reactor

The US Department of Energy's High Flux Isotope Reactor (HFIR) was analyzed to evaluate it's response to a spectrum of loss-of-coolant accidents (LOCAs) with potential for leading to core damage. The MELCOR severe accident analysis code (version 1.7.1) was used to evaluate the overall dynamic response of HFIR. Before conducting LOCA analyses, the steady-state thermal-hydraulic parameters evaluated by MELCOR for various loop sections were verified against steady-state operating data. Thereafter,… more

Date: January 1, 1989

Creator: Taleyarkhan, R.P. (Oak Ridge National Lab., TN (USA))

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Analysis of depressurized loss-of-forced cooling transients by HERA

The Modular High-Temperature Gas-Cooled Reactor (MHTGR) is one of the next generation reactors, which has passive safety features. Among these safety features is the ability to withstand a depressurized, loss-of-forced cooling of the reactor without release of fission products from the primary containment. In order to assess the capability of the MHTGR to withstand this type of accident condition, the thermal behavior of the reactor core must be well understood. To accomplish this, we have empl… more

Date: January 1, 1991

Creator: Rider, W. J. & Cappiello, M. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Evaluation of BWR emergency procedure guidelines for BWR ATWS using RAMONA-3B code

An MSIV Closure ATWS calculation for a typical BWR/4 (Browns Ferry, Unit 1) was performed using the RAMONA-3B code which is a BWR systems transient code combining three-dimensional neutronic core representation with multi-channel one-dimensional thermal hydraulics. The main objective of the study was to perform a best-estimate evaluation of the recently proposed Emergency Procedure Guidelines for Anticipated Transients Without Scram (ATWS). Emphasis was placed on evaluating the effects of lower… more

Date: January 1, 1985

Creator: Neymotin, L.; Slovik, G.; Cazzoli, E. & Saha, P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

ORNL analyses of AVR performance and safety

Because of the high interest in modular High Temperature Reactor performance and safety, a cooperative project has been established involving the Oak Ridge National Laboratory (ORNL), Arbeitsgemeinschaft Versuchs Reaktor GmbH (AVR), and Kernforschungsanlage Juelich GmbH (KFA) in reactor physics, performance and safety. This paper presents initial results of ORNL's examination of a hypothetical depressurized core heatup accident and consideration of how a depressurized core heatup test might be … more

Date: January 1, 1985

Creator: Cleveland, J.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Experiment data report for Semiscale Mod-1 Test S-28-5 (steam generator tube rupture test). [PWR]

Recorded test data are presented for Test S-28-5 of the Semiscale Mod-1 steam generator tube rupture test series. These tests are among several Semiscale Mod-1 experiments conducted to investigate the thermal and hydraulic phenomena accompanying a hypothesized loss-of-coolant accident in a pressurized water reactor (PWR) system. Test S-28-5 was conducted from initial conditions of 15,768 kPa and 556 K to investigate the response of the Semiscale Mod-1 system to a depressurization and reflood tr… more

Date: November 1, 1977

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Experimental Validation of Stratified Flow Phenomena, Graphite Oxidation, and Mitigation Strategies of Air Ingress Accidents

The US Department of Energy is performing research and development (R&D) that focuses on key phenomena that are important during challenging scenarios that may occur in the Next Generation Nuclear Plant (NGNP) Program / GEN-IV Very High Temperature Reactor (VHTR). Phenomena identification and ranking studies (PIRT) to date have identified the air ingress event, following on the heels of a VHTR depressurization, as very important (Schultz et al., 2006). Consequently, the development of advanced … more

Date: December 1, 2008

Creator: Oh, Chang Ho; Kim, Eung Soo; No, Hee Cheon & Cho, Nam Zin

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Petrophysical Characterization and Reservoir Simulator for Methane Gas Production from Gulf of Mexico Hydrates

Gas hydrates are crystalline, ice-like compounds of gas and water molecules that are formed under certain thermodynamic conditions. Hydrate deposits occur naturally within ocean sediments just below the sea floor at temperatures and pressures existing below about 500 meters water depth. Gas hydrate is also stable in conjunction with the permafrost in the Arctic. Most marine gas hydrate is formed of microbially generated gas. It binds huge amounts of methane into the sediments. Estimates of the … more

Date: June 30, 2006

Creator: Mohanty, Kishore; Cook, Bill; Hakimuddin, Mustafa; Pitchumani, Ramanan; Ogunlana, Damiola; Burger, Jon et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Regional and National Estimates of the PotentialEnergy Use, Energy Cost, and CO{sub 2} Emissions Associated with Radon Mitigation by Sub-slab Depressurization

Active sub-slab depressurization (SSD) systems are an effective means of reducing indoor radon concentrations in residential buildings. However, energy is required to operate the system fan and to heat or cool the resulting increased building ventilation. We present regional and national estimates of the energy requirements, operating expenses, and CO{sub 2} emissions associated with using SSD systems at saturation (i.e., in all U.S. homes with radon concentrations above the EPA remediation gui… more

Date: March 1, 1996

Creator: Riley, W. J.; Fisk, W. J. & Gadgil, A. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Status report : guard containment CFD analysis.

Under the auspices of the CEA Cadarache/ANL-US I-NERI project a comprehensive investigation has been made of improvements to the Gen-IV GFR safety case over that of the GCFR safety case twenty five years ago. In particular, it has been concluded and agreed upon [1] that the GFR safety approach for the passive removal of decay heat in a protected depressurization accident with total loss of electric power needs to be different from that taken for the HTRs. The HTR conduction cooldown to the vess… more

Date: March 3, 2006

Creator: Tzanos, C. P.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

ATWS Transients for the 2400 MWt Gas-Cooled Fast Reactor

Reactivity transients have been analyzed with an updated RELAPS-3D (ver. 2.4.2) system model of the pin core design for the 2400MWt gas-cooled fast reactor (GCFR). Additional reactivity parameters were incorporated in the RELAP5 point-kinetics model to account for reactivity feedbacks due to axial and radial expansion of the core, fuel temperature changes (Doppler effect), and pressure changes (helium density changes). Three reactivity transients without scram were analyzed and the incidents we… more

Date: August 5, 2007

Creator: Cheng, L. Y. & Ludewig, H.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Comparison of kinetic and equilibrium reaction models insimulating gas hydrate behavior in porous media

In this study we compare the use of kinetic and equilibriumreaction models in the simulation of gas (methane) hydrate behavior inporous media. Our objective is to evaluate through numerical simulationthe importance of employing kinetic versus equilibrium reaction modelsfor predicting the response of hydrate-bearing systems to externalstimuli, such as changes in pressure and temperature. Specifically, we(1) analyze and compare the responses simulated using both reactionmodels for natural gas pro… more

Date: November 29, 2006

Creator: Kowalsky, Michael B. & Moridis, George J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Scoping Study on the Safety Impact of Valve Spacing in Natural Gas Pipelines

The U.S. Department of Transportation's Pipeline and Hazardous Materials Safety Administration (PHMSA) is responsible for ensuring the safe, reliable, and environmentally sound operation of the nation's natural gas and hazardous liquid pipelines. Regulations adopted by PHMSA for gas pipelines are provided in 49 CFR 192, and spacing requirements for valves in gas transmission pipelines are presented in 49 CFR 192.179. The present report describes the findings of a scoping study conducted by Oak … more

Date: July 1, 2007

Creator: Sulfredge, Charles David

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Physical property changes in hydrate-bearingsediment due to depressurization and subsequent repressurization

Physical property measurements of sediment cores containing natural gas hydrate are typically performed on material exposed at least briefly to non-in situ conditions during recovery. To examine effects of a brief excursion from the gas-hydrate stability field, as can occur when pressure cores are transferred to pressurized storage vessels, we measured physical properties on laboratory-formed sand packs containing methane hydrate and methane pore gas. After depressurizing samples to atmospheric… more

Date: June 1, 2008

Creator: Kneafsey, Timothy; Waite, W.F.; Kneafsey, T.J.; Winters, W.J. & Mason, D.H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

TOUGH+Hydrate v1.0 User's Manual: A Code for the Simulation of System Behavior in Hydrate-Bearing Geologic Media

TOUGH+HYDRATE v1.0 is a new code for the simulation of the behavior of hydrate-bearing geologic systems. By solving the coupled equations of mass and heat balance, TOUGH+HYDRATE can model the non-isothermal gas release, phase behavior and flow of fluids and heat under conditions typical of common natural CH{sub 4}-hydrate deposits (i.e., in the permafrost and in deep ocean sediments) in complex geological media at any scale (from laboratory to reservoir) at which Darcy's law is valid. TOUGH+HYD… more

Date: March 1, 2008

Creator: Moridis, George; Moridis, George J.; Kowalsky, Michael B. & Pruess, Karsten

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Methane Hydrate Formation and Dissociation in a PartiallySaturated Core-Scale Sand Sample

We performed a sequence of tests on a partiallywater-saturated sand sample contained in an x-ray transparent aluminumpressure vessel that is conducive to x-ray computed tomography (CT)observation. These tests were performed to gather data for estimation ofthermal properties of the sand/water/gas system and thesand/hydrate/water/gas systems, as well as data to evaluate the kineticnature of hydrate dissociation. The tests included mild thermalperturbations for the estimation of the thermal proper… more

Date: November 3, 2005

Creator: Kneafsey, Timothy J.; Tomutsa, Liviu; Moridis, George J.; Seol,Yongkoo; Freifeld, Barry M.; Taylor, Charles E. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Application of Gamma code coupled with turbomachinery models for high temperature gas-cooled reactors

The very high-temperature gas-cooled reactor (VHTR) is envisioned as a single- or dual-purpose reactor for electricity and hydrogen generation. The concept has average coolant temperatures above 9000C and operational fuel temperatures above 12500C. The concept provides the potential for increased energy conversion efficiency and for high-temperature process heat application in addition to power generation. While all the High Temperature Gas Cooled Reactor (HTGR) concepts have sufficiently high … more

Date: February 1, 2008

Creator: Oh, Chang

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Comparison of kinetic and equilibrium reaction models insimulating the behavior of porous media

Date: November 29, 2006

Creator: Kowalsky, Michael B. & Moridis, George J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Implications of Air Ingress Induced by Density-Difference Driven Stratified Flow

One of the design basis accidents for the Next Generation Nuclear Plant (NGNP), a high temperature gas-cooled reactor, is air ingress subsequent to a pipe break. Following a postulated double-ended guillotine break in the hot duct, and the subsequent depressurization to nearly reactor cavity pressure levels, air present in the reactor cavity will enter the reactor vessel via density-gradient-driven-stratified flow. Because of the significantly higher molecular weight and lower initial temperatu… more

Date: June 1, 2008

Creator: Oh, Chang; Kim, Eung Soo; Schultz, Richard; Petti, David & Liou, C. P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Application of NUREG-1150 methods and results to accident management

The use of NUREG-1150 and similar Probabilistic Risk Assessments in NRC and industry risk management programs is discussed. Risk management'' is more comprehensive than the commonly used term accident management.'' Accident management includes strategies to prevent vessel breach, mitigate radionuclide releases from the reactor coolant system, and mitigate radionuclide releases to the environment. Risk management also addresses prevention of accident initiators, prevention of core damage, and im… more

Date: January 1, 1990

Creator: Dingman, S.; Sype, T.; Camp, A. & Maloney, K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Microseismic activity observed during depressurization of an oil storage cavern in rock salt

In November 1978, the Los Alamos National Laboratory installed a triaxial downhole geophone package at the Bryan Mound Strategic Petroleum Reserve, a salt dome near Freeport, Texas. Monitoring was for the purpose of detecting microseismic activity during the depressurization of one of the oil storage caverns. Seismic activity started soon after the start of depressurization, reached a peak 5 days later, and rapidly died off. Nineteen locatable microearthquakes with magnitudes between -1 and -2 … more

Date: January 1, 1981

Creator: Albright, J. & Pearson, C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Generic risk insights for General Electric boiling water reactors

A methodology has been developed to extract generic risk-based information from probabilistic risk assessments (PRAs) of General Electric boiling water rectors and applying the insights gained to plants that have not been subjected to a PRA. The available risk assessments (six plants) were examined to identify the most probable, i.e., dominant accident sequences at each plants. The goal was to include all sequences which represented at least 80% of core damage frequency. If the same plant speci… more

Date: May 1991

Creator: Travis, R.; Taylor, J. & Chung, J. (Nuclear Regulatory Commission, Washington, DC (USA). Office of Nuclear Reactor Regulation)

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Thermohydraulics in a high-temperature gas-cooled reactor primary loop during early phases of unrestricted core-heatup accidents

In High Temperature Gas Cooled Reactor (HTGR) siting considerations, the Unrestricted Core Heatup Accidents (UCHA) are considered as accidents of highest consequence, corresponding to core meltdown accidents in light water reactors. Initiation of such accidents can be, for instance, due to station blackout, resulting in scram and loss of all main loop forced circulation, with none of the core auxiliary cooling system loops being started. The result is a slow but continuing core heatup, extendin… more

Date: January 1, 1983

Creator: Kroeger, P. G.; Colman, J. & Hsu, C. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Identification and initial assessment of candidate BWR late-phase in-vessel accident management strategies

Work sponsored by the United States Nuclear Regulatory Commission (USNRC) to identify and perform preliminary assessments of candidate BWR (boiling water reactor) in-vessel accident management strategies was completed at Oak Ridge National Laboratory (ORNL) during fiscal year 1990. Mitigative strategies for containment events have been the subject of a companion study at Brookhaven National Laboratory. The focus of this Oak Ridge effort was the development of new strategies for mitigation of th… more

Date: April 15, 1991

Creator: Hodge, S.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department