Abstract
Hydrogen can be produced in undesired ways such as a high temperature metal oxidation during an accident. In this case, the hydrogen must be carefully managed. A hydrogen mitigation system (HMS) should be installed to protect a containment of a nuclear power plant (NPP) from hazards of hydrogen produced by an oxidation of the fuel cladding during a severe accident in an NPP. Among hydrogen removal devices, passive auto-catalytic recombiners (PARs) are currently applied to many NPPs because of passive characteristics, such as not requiring a power supply nor an operators’ manipulations. However, they offer several disadvantages, resulting in issues related to hydrogen control by PARs. One of the issues is a hydrogen stratification in which hydrogen is not well-mixed in a compartment due to the high temperature exhaust gas of PARs and accumulation in the lower part. Therefore, experimental simulation on hydrogen stratification phenomenon by PARs is required. When the hydrogen stratification by PARs is observed in the experiment, the verification and improvement of a PAR analysis model using the experimental results can be performed, and the hydrogen removal characteristics by PARs installed in an NPP can be evaluated using the improved PAR model.
Highlights
During a severe accident involving a damage to a reactor core in a nuclear power plant (NPP), hydrogen is produced by oxidation of the nuclear fuel cladding, and the hydrogen is released into the reactor containment building along with water vapor
An experimental simulation was conducted to evaluate the possibility flow rate of hydrogen injected, and the second is to evaluate the behavior of hydrogen according the stratification due to passive auto-catalytic recombiners (PARs) installed in a containment building during a severe accident. toTwo location or arrangement of the
This confirms that the phenomenon of the hydrogen stratification induced by Another interesting thing found in the Spray–Aerosol-Recombiner-combustion testtest facility (SPARC)‐PAR experiment is that the hydrogen concentration at the location below the hydrogen injection nozzle (H1) continuously increases and reaches the highest value which is thought to be induced by the PAR activation
Summary
During a severe accident involving a damage to a reactor core in a nuclear power plant (NPP), hydrogen is produced by oxidation of the nuclear fuel cladding, and the hydrogen is released into the reactor containment building along with water vapor. The high-temperature exhaust gas emitted from the PAR can be accumulated in the upper part of the compartment in which the PAR is installed because the exhaust gas density is relatively low compared to the containment atmosphere When it happens, it may prevent the formation of a large natural convection caused by the PAR in the compartment. It may prevent the formation of a large natural convection caused by the PAR in the compartment In this case, a hydrogen gas released at the lower compartment area may lose a buoyancy force and mobility by the high-temperature exhaust gas occupying the upper part of the containment. A hydrogen gas released at the lower compartment area may lose a buoyancy force and mobility by the high-temperature exhaust gas occupying the upper part of the containment This phenomenon is called PAR-induced hydrogen stratification.
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