K. Morita - Academia.edu (original) (raw)

Papers by K. Morita

Research paper thumbnail of Safety Improvements for ADS Transmuters with Dedicated Fuel

For obtaining maximum transmutation and incineration rates of minor actinides (MAs) in Accelerato... more For obtaining maximum transmutation and incineration rates of minor actinides (MAs) in Accelerator Driven Systems (ADSs) so- called dedicated fuels should be utilized. These fuels are characterized by a high MA content and the lack of the classical fertile materials as U238 or Th232. Dedicated fuels still have to be developed and programs are under way for their fabrication, irradiation and testing. In Europe, mainly the oxide- route is investigated and developed. A dedicated core will contain multiple 'critical' fuel masses, resulting in a certain recriticality potential under core degradation conditions. The use of dedicated fuels may also lead to a strong deterioration of the safety parameters of the reactor core as e.g. the void worth, the Doppler or the kinetics quantities, as neutron generation time and βeff. Current knowledge suggests that 'critical' reactors may not be feasible, because of safety reasons. However, for ADSs, it is assumed that due to the s...

Research paper thumbnail of Particle Effects on Penetration and Solidification of Flowing Mixed Melts on Metal Structures

Journal of Nuclear Science and Technology, 2011

Research paper thumbnail of A new algorithm for surface tension model in moving particle methods

International Journal for Numerical Methods in Fluids, 2007

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS Int. J. Numer. Meth. Fluids 2007; 55:225–24... more INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS Int. J. Numer. Meth. Fluids 2007; 55:225–240 Published online 28 February 2007 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/fld.1448 ... A new algorithm for surface ...

Research paper thumbnail of Development of multicomponent vaporization/condensation model for a reactor safety analysis code SIMMER-III

Nuclear Engineering and Design, 2003

It is believed that the numerical simulation of thermal-hydraulic phenomena of multiphase, multic... more It is believed that the numerical simulation of thermal-hydraulic phenomena of multiphase, multicomponent flows in a reactor core is essential to investigate core disruptive accidents (CDAs) of liquid-metal fast reactors. A new multicomponent vaporization/condensation (V/C) model was developed to provide a generalized model for a fast reactor safety analysis code SIMMER-III, which analyzes relatively short-timescale phenomena relevant to accident sequences of CDAs. The model characterizes the V/C process associated with phase transition through heat-transfer and mass-diffusion limited models to follow the time evolution of the reactor core under CDA conditions. The heat-transfer limited model describes the nonequilibrium phase-transition processes occurring at interfaces, while the mass-diffusion limited model is employed to represent effects of noncondensable gases and multicomponent mixture on V/C processes. Verification of the model and method employed in the multicomponent V/C model of SIMMER-III was performed successfully by analyzing a series of multicomponent phase-transition experiments.

Research paper thumbnail of SIMMER-III applications to fuel–coolant interactions

Nuclear Engineering and Design, 1999

The main purpose of the fast reactor safety analysis code, SIMMER-III, is to provide a numerical ... more The main purpose of the fast reactor safety analysis code, SIMMER-III, is to provide a numerical simulation of complex multiphase, multicomponent flow problems essential to investigate core disruptive accidents in liquid-metal fast reactors (LMFRs). However, the code is designed to be sufficiently flexible to be applied to a variety of multiphase flows, in addition to LMFR safety issues. In the present study, some typical experiments relating to fuel-coolant interactions (FCIs) have been analyzed by SIMMER-III to demonstrate that the code is applicable to such complex and highly transient multiphase flow situations. It is shown that SIMMER-III can reproduce the premixing phase both in water and sodium systems as well as the propagation of steam explosion. It is thus demonstrated the code is basically capable of simulating integral multiphase thermal-hydraulic problems included in FCI experiments.

Research paper thumbnail of A Review on Safety Issues and Analysis Tools for Accelerator Driven Systems and Transmuters

The accelerator driven transmuter systems (ADTs) introduce three innovations, compared e.g. to cr... more The accelerator driven transmuter systems (ADTs) introduce three innovations, compared e.g. to critical sodium cooled fast spectrum burner reactors. A subcritical reactor driven by an external neutron source, the heavy metal coolant and the new dedicated fuels. All three innovations introduce new interrelated safety issues. Besides the dynamics of the subcritical system and the chosen Pb/Bi or Pb coolant, especially

Research paper thumbnail of Safety Improvements for ADS Transmuters with Dedicated Fuel

For obtaining maximum transmutation and incineration rates of minor actinides (MAs) in Accelerato... more For obtaining maximum transmutation and incineration rates of minor actinides (MAs) in Accelerator Driven Systems (ADSs) so- called dedicated fuels should be utilized. These fuels are characterized by a high MA content and the lack of the classical fertile materials as U238 or Th232. Dedicated fuels still have to be developed and programs are under way for their fabrication, irradiation and testing. In Europe, mainly the oxide- route is investigated and developed. A dedicated core will contain multiple 'critical' fuel masses, resulting in a certain recriticality potential under core degradation conditions. The use of dedicated fuels may also lead to a strong deterioration of the safety parameters of the reactor core as e.g. the void worth, the Doppler or the kinetics quantities, as neutron generation time and βeff. Current knowledge suggests that 'critical' reactors may not be feasible, because of safety reasons. However, for ADSs, it is assumed that due to the s...

Research paper thumbnail of Particle Effects on Penetration and Solidification of Flowing Mixed Melts on Metal Structures

Journal of Nuclear Science and Technology, 2011

Research paper thumbnail of A new algorithm for surface tension model in moving particle methods

International Journal for Numerical Methods in Fluids, 2007

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS Int. J. Numer. Meth. Fluids 2007; 55:225–24... more INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS Int. J. Numer. Meth. Fluids 2007; 55:225–240 Published online 28 February 2007 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/fld.1448 ... A new algorithm for surface ...

Research paper thumbnail of Development of multicomponent vaporization/condensation model for a reactor safety analysis code SIMMER-III

Nuclear Engineering and Design, 2003

It is believed that the numerical simulation of thermal-hydraulic phenomena of multiphase, multic... more It is believed that the numerical simulation of thermal-hydraulic phenomena of multiphase, multicomponent flows in a reactor core is essential to investigate core disruptive accidents (CDAs) of liquid-metal fast reactors. A new multicomponent vaporization/condensation (V/C) model was developed to provide a generalized model for a fast reactor safety analysis code SIMMER-III, which analyzes relatively short-timescale phenomena relevant to accident sequences of CDAs. The model characterizes the V/C process associated with phase transition through heat-transfer and mass-diffusion limited models to follow the time evolution of the reactor core under CDA conditions. The heat-transfer limited model describes the nonequilibrium phase-transition processes occurring at interfaces, while the mass-diffusion limited model is employed to represent effects of noncondensable gases and multicomponent mixture on V/C processes. Verification of the model and method employed in the multicomponent V/C model of SIMMER-III was performed successfully by analyzing a series of multicomponent phase-transition experiments.

Research paper thumbnail of SIMMER-III applications to fuel–coolant interactions

Nuclear Engineering and Design, 1999

The main purpose of the fast reactor safety analysis code, SIMMER-III, is to provide a numerical ... more The main purpose of the fast reactor safety analysis code, SIMMER-III, is to provide a numerical simulation of complex multiphase, multicomponent flow problems essential to investigate core disruptive accidents in liquid-metal fast reactors (LMFRs). However, the code is designed to be sufficiently flexible to be applied to a variety of multiphase flows, in addition to LMFR safety issues. In the present study, some typical experiments relating to fuel-coolant interactions (FCIs) have been analyzed by SIMMER-III to demonstrate that the code is applicable to such complex and highly transient multiphase flow situations. It is shown that SIMMER-III can reproduce the premixing phase both in water and sodium systems as well as the propagation of steam explosion. It is thus demonstrated the code is basically capable of simulating integral multiphase thermal-hydraulic problems included in FCI experiments.

Research paper thumbnail of A Review on Safety Issues and Analysis Tools for Accelerator Driven Systems and Transmuters

The accelerator driven transmuter systems (ADTs) introduce three innovations, compared e.g. to cr... more The accelerator driven transmuter systems (ADTs) introduce three innovations, compared e.g. to critical sodium cooled fast spectrum burner reactors. A subcritical reactor driven by an external neutron source, the heavy metal coolant and the new dedicated fuels. All three innovations introduce new interrelated safety issues. Besides the dynamics of the subcritical system and the chosen Pb/Bi or Pb coolant, especially