Gas coolant at low pressure exhibits poor heat transfer characteristics. This is an area of conce... more Gas coolant at low pressure exhibits poor heat transfer characteristics. This is an area of concern for the passive response targeted by the Generation IV GCFR design. For the first 24 hour period, the decay heat removal for the GCFR design is dependent on an actively powered blower, which also would reduce the temperature in the fuel during transients, before depending on the passive operation. Natural circulation cooling initiates when the blower is stopped for the final phase of the decay heat removal, as under forced convection the core decay heat is adequately cooled by the running blower. The ability of the coolant to flow in the reverse direction or having recirculation, when the blowers are off, necessitates more understanding of the flow behavior characteristics in the upper plenum. The work done here focuses primarily on the period after the blower has been turned off, as the core is adequately cooled when the blowers are running, thus there was no need to carry out the an...
2010 14th International Heat Transfer Conference, Volume 7, 2010
The Idaho National Laboratory (INL), under the auspices of the U.S. Department of Energy, is perf... more The Idaho National Laboratory (INL), under the auspices of the U.S. Department of Energy, is performing research and development that focuses on key phenomena important during potential scenarios that may occur in very high temperature reactors (VHTRs). Phenomena Identification and Ranking Studies to date have ranked an air ingress event, following on the heels of a VHTR depressurization, as important
An improved nuclear fission reactor of the continuous fueling type involves determining an asympt... more An improved nuclear fission reactor of the continuous fueling type involves determining an asymptotic equilibrium state for the nuclear fission reactor and providing the reactor with a moderator-to-fuel ratio that is optimally moderated for the asymptotic equilibrium state of the nuclear fission reactor; the fuel-to-moderator ratio allowing the nuclear fission reactor to be substantially continuously operated in an optimally moderated
The High Temperature Reactor (HTR) and Very High Temperature Reactor (VHTR) are types of nuclear ... more The High Temperature Reactor (HTR) and Very High Temperature Reactor (VHTR) are types of nuclear power plants that, as the names imply, operate at temperatures above those of the conventional nuclear power plants that currently generate electricity in the US and other countries. Like existing nuclear plants, heat generated from the fission of uranium or plutonium atoms is carried off
Fourth International Topical Meeting on High Temperature Reactor Technology, Volume 1, 2008
In this paper, a new neutron kinetics solver for cylindrical R-Z geometry, CYNOD, is presented fo... more In this paper, a new neutron kinetics solver for cylindrical R-Z geometry, CYNOD, is presented for the simulation of coupled transient problems for pebble bed reactors. The code utilizes the Direct Coarse Mesh Finite Difference method, in which a set of one-dimensional equations in each transverse direction is solved by means of the analytic Green’s function method. A method that deals with control rod cusping problems is also presented. A heterogeneous fuel kernel model is implemented in order to accurately take into account Doppler feedback effects. Numerical results that demonstrate the accuracy of the code are also presented.
An LDRD (Laboratory Directed Research and Development) project is ongoing at the Idaho National E... more An LDRD (Laboratory Directed Research and Development) project is ongoing at the Idaho National Engineering and Environmental Laboratory (INEEL) for applying the three-dimensional multi-group deterministic neutron transport code (Attila{reg_sign}) to criticality, flux and depletion calculations of the Advanced Test Reactor (ATR). This paper discusses the model development, capabilities of Attila, generation of the cross-section libraries, and comparisons to an ATR MCNP model and future.
The PEBBED code was developed at the Idaho National Laboratory for design and analysis of pebble-... more The PEBBED code was developed at the Idaho National Laboratory for design and analysis of pebble-bed high temperature reactors. The diffusion-depletion-pebble-mixing algorithm of the original PEBBED code was enhanced through coupling with the THERMIX-KONVEK code for thermal fluid analysis and by the COMBINE code for online cross section generation. The COMBINE code solves the B-1 or B-3 approximations to the transport equation for neutron slowing down and resonance interactions in a homogeneous medium with simple corrections for shadowing and thermal self-shielding. The number densities of materials within specified regions of the core are averaged and transferred to COMBINE from PEBBED for updating during the burnup iteration. The simple treatment of self-shielding in previous versions of COMBINE led to inaccurate results for cross sections and unsatisfactory core performance calculations. A new version of COMBINE has been developed that treats all levels of heterogeneity using the...
Gas coolant at low pressure exhibits poor heat transfer characteristics. This is an area of conce... more Gas coolant at low pressure exhibits poor heat transfer characteristics. This is an area of concern for the passive response targeted by the Generation IV GCFR design. For the first 24 hour period, the decay heat removal for the GCFR design is dependent on an actively powered blower, which also would reduce the temperature in the fuel during transients, before depending on the passive operation. Natural circulation cooling initiates when the blower is stopped for the final phase of the decay heat removal, as under forced convection the core decay heat is adequately cooled by the running blower. The ability of the coolant to flow in the reverse direction or having recirculation, when the blowers are off, necessitates more understanding of the flow behavior characteristics in the upper plenum. The work done here focuses primarily on the period after the blower has been turned off, as the core is adequately cooled when the blowers are running, thus there was no need to carry out the an...
2010 14th International Heat Transfer Conference, Volume 7, 2010
The Idaho National Laboratory (INL), under the auspices of the U.S. Department of Energy, is perf... more The Idaho National Laboratory (INL), under the auspices of the U.S. Department of Energy, is performing research and development that focuses on key phenomena important during potential scenarios that may occur in very high temperature reactors (VHTRs). Phenomena Identification and Ranking Studies to date have ranked an air ingress event, following on the heels of a VHTR depressurization, as important
An improved nuclear fission reactor of the continuous fueling type involves determining an asympt... more An improved nuclear fission reactor of the continuous fueling type involves determining an asymptotic equilibrium state for the nuclear fission reactor and providing the reactor with a moderator-to-fuel ratio that is optimally moderated for the asymptotic equilibrium state of the nuclear fission reactor; the fuel-to-moderator ratio allowing the nuclear fission reactor to be substantially continuously operated in an optimally moderated
The High Temperature Reactor (HTR) and Very High Temperature Reactor (VHTR) are types of nuclear ... more The High Temperature Reactor (HTR) and Very High Temperature Reactor (VHTR) are types of nuclear power plants that, as the names imply, operate at temperatures above those of the conventional nuclear power plants that currently generate electricity in the US and other countries. Like existing nuclear plants, heat generated from the fission of uranium or plutonium atoms is carried off
Fourth International Topical Meeting on High Temperature Reactor Technology, Volume 1, 2008
In this paper, a new neutron kinetics solver for cylindrical R-Z geometry, CYNOD, is presented fo... more In this paper, a new neutron kinetics solver for cylindrical R-Z geometry, CYNOD, is presented for the simulation of coupled transient problems for pebble bed reactors. The code utilizes the Direct Coarse Mesh Finite Difference method, in which a set of one-dimensional equations in each transverse direction is solved by means of the analytic Green’s function method. A method that deals with control rod cusping problems is also presented. A heterogeneous fuel kernel model is implemented in order to accurately take into account Doppler feedback effects. Numerical results that demonstrate the accuracy of the code are also presented.
An LDRD (Laboratory Directed Research and Development) project is ongoing at the Idaho National E... more An LDRD (Laboratory Directed Research and Development) project is ongoing at the Idaho National Engineering and Environmental Laboratory (INEEL) for applying the three-dimensional multi-group deterministic neutron transport code (Attila{reg_sign}) to criticality, flux and depletion calculations of the Advanced Test Reactor (ATR). This paper discusses the model development, capabilities of Attila, generation of the cross-section libraries, and comparisons to an ATR MCNP model and future.
The PEBBED code was developed at the Idaho National Laboratory for design and analysis of pebble-... more The PEBBED code was developed at the Idaho National Laboratory for design and analysis of pebble-bed high temperature reactors. The diffusion-depletion-pebble-mixing algorithm of the original PEBBED code was enhanced through coupling with the THERMIX-KONVEK code for thermal fluid analysis and by the COMBINE code for online cross section generation. The COMBINE code solves the B-1 or B-3 approximations to the transport equation for neutron slowing down and resonance interactions in a homogeneous medium with simple corrections for shadowing and thermal self-shielding. The number densities of materials within specified regions of the core are averaged and transferred to COMBINE from PEBBED for updating during the burnup iteration. The simple treatment of self-shielding in previous versions of COMBINE led to inaccurate results for cross sections and unsatisfactory core performance calculations. A new version of COMBINE has been developed that treats all levels of heterogeneity using the...
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