JP2017067744A - Method for sealing cracks of reactor vessel and reactor containment vessel by using water vapor in air - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stop leaking from all of cracks that are presumed to be formed at a tremendous number of portions of a reactor containment vessel due to explosion in an accident, so as to stop leaking of a cooling water from a reactor vessel, to stop outflow of radioactivity in gas, liquid, and solid states which are emitted from fuel debris to prevent it from releasing into the atmosphere, and to secure safety of workers physically as well as with respect to radiation.SOLUTION: Ice particles, liquid nitrogen, dry ice, cooling air, or the like is put or circulated in a reactor vessel, a reactor containment vessel, and a pressure suppression chamber, and air is exhausted from the vessels and the chamber. The exhausted air is discharged in the atmosphere after passing a filter such that radioactivity is removed therefrom, which causes inside of the reactor containment vessel to be under negative pressure, thereby allowing air to flow into the reactor containment vessel through cracks 7 and gaps. Water vapor 8 contained in the air is cooled and dew-condensed on outer wall surfaces of the vessels and the chamber, and dew-condensed water 9 of the water vapor 8 is vacuumed through the cracks 7 and gaps and further cooled to freeze such that the cracks, the gaps, and portions therearound are blocked with ice 10 to seal the vessels and the chamber and stop leakage.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method of sealing off cracks generated in a nuclear reactor vessel or containment vessel in an accident.

On March 11, 2011, the Fukushima Daiichi nuclear power plant from Unit 1 to Unit 3 melted due to the Great East Japan Earthquake.
There is an urgent need to seal the containment vessel and reactor vessel as the first step in decommissioning measures. At present, no drastic construction method has been found.

Conventionally, the cracks in the containment vessel have been repaired by welding. Currently, in Fukushima, where repairs are performed under high radiation, welding by a remote robot without human work is being studied.

  There is no method to safely and inexpensively seal damaged reactor vessels and containment vessels.

  The present invention circulates or fills ice particles, liquid nitrogen, dry ice, cooling air, or the like in a reactor vessel, containment vessel, and pressure suppression chamber melted in the core, and cools the vessel and the chamber. The air in the room or room is exhausted, and the water vapor contained in the air is cooled and condensed on the outer surface of the container and the room, and the condensed water is sucked inward through the crevices and the gaps. It is further cooled to become ice and closes the cracks and gaps to prevent leakage from the reactor vessel and containment vessel.

  It is assumed that the containment vessel has gaps and gaps at enormous locations due to explosions at the time of the accident, and it is necessary to stop all leaks.

  It is necessary to take drastic measures against the fact that the cooling water that cools fuel debris is activated and leaks from Kiretsu into the ground in large quantities and the pollution is spreading.

  It is necessary to take drastic measures against the surrounding groundwater invading into the concrete in the lower part of the PCV and increasing radioactive contamination.

  Regardless of whether fuel debris is being stored or being recovered, the release of gas, liquid, and solid radioactivity released from fuel debris must be prevented and not released into the environment. Even if the inside of the container is negative pressure controlled and air is introduced from the outside through damaged crevices and gaps, internal contaminants often flow backward from the crevices and gaps and are released into the environment. There is an urgent need for countermeasures.

  Fill or circulate ice particles, liquid nitrogen, dry ice, or cooling air in the reactor vessel, containment vessel, and pressure suppression chamber.

  Air is exhausted from the reactor vessel, containment vessel, and pressure suppression chamber.

  The exhausted air passes through a filter, removes radioactivity and releases it to the atmosphere.

  The exhausted air passes through a filter, removes radioactivity and releases it to the atmosphere.

  Induced by the previous section, the inside of the reactor vessel, containment vessel, and pressure suppression chamber becomes negative pressure, and air flows from outside air through a crack or a gap.

  Water vapor contained in the air outside the container and the room is cooled and condensed on the outer surface of the container and the room, and the condensed water is sucked into the crevices and gaps and further cooled to form ice, closing the crevices and the gaps. The chamber is sealed, leaks are prevented at low cost, this phenomenon continues as long as there is a leak, and it can be stably sealed without specifying the location, and even if a crack or a gap occurs afterwards, the inside of the container is under negative pressure As soon as it is automatically repaired.

  FIG. 1 is an image of sealing a damaged reactor vessel, containment vessel, and pressure suppression chamber.

  FIG. 2 is an image diagram in which water vapor in the air passing through the cracks and gaps freezes.

FIG. 1 is an image view of sealing a reactor vessel 1, a containment vessel 2, and a pressure suppression chamber 3 damaged by fuel debris 4 dropped from the reactor vessel 1. The reactor vessel 1, the containment vessel 2, and the pressure suppression chamber 3 are filled or circulated with liquid nitrogen 5 through the cooling pipe 6. The exhausted air passes through a filter, removes radioactivity and releases it to the atmosphere. The inside of the reactor vessel, the containment vessel, and the pressure suppression chamber has a negative pressure, and air flows from outside air through a crack or a gap.
FIG. 2 shows that water vapor 8 contained in the air is cooled on the outer surface of the container and on the outer surface of the container and the chamber to form condensed water 9, and the condensed water is sucked into the container through the crystal 7 and further cooled by the crystal 7. It shows a state where the ice 10 is formed and the crack 7 is blocked.

  It can be used for events that require the containment of dangerous goods in damaged containers.

1. Reactor vessel 2. 2. containment vessel 3. Pressure suppression chamber 4. Fuel debris Liquid nitrogen 6. Cooling pipe Kiretsu 8 Water vapor 9. Water 10 ice

Claims (1)

    Fill or circulate liquid nitrogen, dry ice, or cooling air in reactor vessels, containment vessels, and pressure suppression chambers that have been damaged due to accidents and have gaps or gaps, and cool those containers and chambers. The air in the container or the room is exhausted, and the water vapor contained in the air is cooled and condensed on the outer surface of the container and the room, and the condensed water is sucked inward through the crystal and the gap, and the crystal and the gap and the A construction method characterized in that it is further cooled in the vicinity to become ice and closes the cracks and gaps and the vicinity thereof to prevent leakage from the reactor vessel, containment vessel, and pressure suppression chamber.

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