Abstract: A liquefied gas storage tank includes a corner block disposed on a corner portion, wherein the corner block includes a lower block, an upper block and an upper connecting block, the upper block includes a first inner fixing unit and a second inner fixing unit respectively provided inside a first surface and a second surface, bonded and connected to a secondary barrier, and each having a structure in which a primary inner plywood, a primary corner insulating material, and a primary outer plywood are stacked, and an inner bent portion installed at a corner spatial portion between the first inner fixing unit and the second inner fixing unit, and both side surfaces of the inner bent portion that are perpendicular to the secondary barrier each have a height reduced from a total height of each of the first and second inner fixing units.

Abstract: The liquefied gas storage tank includes a primary barrier, a primary insulation wall, a secondary barrier, and a secondary insulation wall. In a state where unit elements are arranged adjacent to each other, each of the unit elements being formed by stacking the secondary insulation wall, the secondary barrier, and a fixed insulation wall which is a part of the primary insulation wall, the primary insulation wall may comprise: a connection insulation wall provided in the space between the adjacent fixed insulation walls; first slits formed between the fixed insulation walls and the connection insulation wall when the connection insulation wall is inserted and installed between the adjacent fixed insulation walls; a plurality of second slits formed in a lengthwise direction and a widthwise direction of the fixed insulation walls; and a first insulating filler material for filling the first slits.

Abstract: An underwater decommissioning method of a nuclear facility including a nuclear reactor pressure vessel and bio-protective concrete comprising a cavity in which the nuclear reactor pressure vessel is positioned is disclosed. The method includes: (a) lifting the nuclear reactor pressure vessel above the cavity; (b) forming an insertion part in the bio-protective concrete adjacent to the cavity, filling the insertion part with water, and installing a support part on a bottom surface of the insertion part; (c) inserting the nuclear reactor pressure vessel in the insertion part and mounting a lower portion of the nuclear reactor pressure vessel on the support part; and (d) repeatedly cutting portions of the nuclear reactor pressure vessel mounted on the support part by using a cutting device in an underwater position. The method allows performing cutting operations in the water, and thus, it is possible to prevent radiation exposure due to occurrence of dust.

Abstract: A radioactive structure dismantling method of a heavy water reactor facility that includes a calandria including a main shell and a sub shell, a calandria vault that receives the calandria therein, and a cover assembly that covers the calandria according to an embodiment, includes: preparing dismantling of the calandria; dismantling a reactor pipe installed in the calandria; dismantling the cover assembly that covers the calandria; dismantling the calandria; and dismantling the calandria vault.

Abstract: A method for complex-decommissioning a nuclear facility is disclosed. The method for complex-decommissioning the nuclear facility includes: cutting and expanding an inner wall of the cavity; installing a cutting device that cuts and decommissions the nuclear reactor pressure vessel inside the cavity; fixing the nuclear reactor pressure vessel inside the cavity by using a fixture; and cutting and decommissioning the nuclear reactor pressure vessel fixed inside the cavity by using a cutting device.

Abstract: A method for decommissioning a heavy water reactor facility includes: opening an upper part of the calandria vault; inserting a support device into an inner part of the calandria vault through the upper part of the calandria vault to support the main shell of the calandria; cutting between the main shell and the sub-shell of the calandria by inserting a cutting device into the inner part of the calandria vault through the upper part of the calandria vault; and drawing out the main shell of the calandria to the outside of the calandria vault by moving the support device from the inner part of the calandria vault to the outside through the upper part.

Abstract: A device for separating a shielding slab for a heavy water reactor according to an embodiment includes: a body; a circular rail installed on at least one side of the body; and a decommissioner for decommissioning a shielding slab installed on the circular rail and installed on an inner wall of a heavy water reactor, wherein the decommissioner includes a decommission head moving on the circular rail, a separator installed in the decommission head and separating and desalinizing the shielding slab, and a gripper installed in the decommission head and gripping the separated shielding slab.

Abstract: A nuclear reactor dismantlement system according to an embodiment includes bio-protective concrete including a first space into which a reactor is inserted and a second space that is connected to the first space and is expanded in the first space, a moving device that is positioned in the second space and moves the reactor, and a cutting device that is positioned in the second space and cuts the reactor.

Abstract: An exemplary embodiment of the present invention provides an apparatus for dismantling for heavy water reactor facilities, including: a cutting device configured to divide a calandria of the heavy water reactor facilities into a main shell and a sub-shell; and a transfer device configured to draw the main shell cut by the cutting device to the outside, wherein the transfer device includes a fixing unit configured to fix the calandria; and a transfer unit configured to transfer the fixing unit.

Abstract: A decommissioning method of biological shielding concrete of a nuclear power plant according to an exemplary embodiment includes: decommissioning a neutron detector positioning device installed to biological shielding concrete surrounding a nuclear reactor to form a plurality of penetrated parts in the biological shielding concrete; inserting a part of a cutting device into the plurality of penetrated parts; and decomposing the biological shielding concrete into a plurality of sub-concrete parts by using the cutting device.

Abstract: An apparatus for treating waste of a nuclear reactor pressure vessel includes: a suction unit inserted into the nuclear reactor pressure vessel through a plurality of through-pipes passing through a lower portion of the nuclear reactor pressure vessel to suck waste inside the nuclear reactor pressure vessel; a waste treatment part connected to the suction unit to treat the waste; and a lower collection part connected to the waste treatment part to be positioned under the nuclear reactor pressure vessel with the suction unit therebetween.

Abstract: An exposure dose measurement simulation device according to an embodiment of the present invention includes: a virtual work area generating portion that generates a virtual work area corresponding to a work area of a radiation facility; and an exposure dose prediction portion that predicts an exposure dose of a worker positioned in the virtual work area, wherein the exposure dose prediction portion includes a database portion that includes first data on a spatial dose rate of the radiation facility and second data on a position of a radiation source in the radiation facility, and a first exposure dose calculation portion that calculates the exposure dose of the worker positioned in the virtual work area using the first data and second data.

Abstract: A method for decommissioning a nuclear facility includes: separating a nuclear reactor pressure vessel from biodegradable concrete; decommissioning a concrete structure; covering the biodegradable concrete; and decommissioning the biodegradable concrete.

Abstract: A method of decommissioning a nuclear facility including a plurality of sandboxes that cover a plurality of upper penetration holes, includes: exposing the plurality of pipes through the plurality of upper penetration holes by removing the plurality of sandboxes; and cutting the plurality of pipes through the plurality of upper penetration holes.

Abstract: A method of decommissioning a nuclear facility, including: exposing the plurality of upper penetration holes by removing the plurality of sandboxes; enlarging an upper space of the cavity by cutting an upper portion of the biological shield concrete that is disposed between the plurality of upper penetration holes and between the plurality of upper penetration holes and the cavity; and separating the nuclear reactor pressure vessel from the biological shield concrete.

Abstract: A plasma torch has a torch body provided with a plurality of stacked torch body segments disposed between a rear electrode unit and a front electrode unit. The torch body forms a circular channel through which gas flows in an axial direction. Each torch body segment has a circular disc shape in which a central circular through-hole is formed to form the channel. Each segment includes gas supply ports defining a spiral-shaped flow path along the through hole on a first side of the segment so as to introduce a reactive gas, a cooling flow path, a cooling water supply flow path, a cooling water discharge flow path, a gas supply flow path, a gas branch flow path, a cooling water supply branch flow path, and a cooling water discharge branch flow path.

Abstract: A device for removing shielding balls from calandria of a heavy water reactor is provided. The device includes a head for moving the shielding balls positioned inside of an end shield of the calandria to an outside of the end shield; and a mover for moving the head to the end shield of the calandria. The head includes a head body, an opening former installed on the head body and configured to form an opening in the end shield, and a gate installed on the head body and configured to control an amount of the shielding balls discharged to the outside through the opening.

Abstract: An apparatus for decommissioning heavy-water reactor facilities includes a shielding device including a drawing-out space that is mounted on the reactivity mechanism deck and communicates with one through-hole among the plurality of through-holes, a separating device that is inserted into the inside of one of the plurality of guide tubes through the drawing-out space and the one through-hole and cuts an end portion of the one guide tube connected to the calandria, and a drawing-out device that is inserted into the inside of the one guide tube through the drawing-out space and the one through-hole and supports the end portion of the one guide tube to draw out the one guide tube into the inside of the drawing-out space through the one through-hole.

Abstract: A metal oxide barrier and a connecting method for solving the problems in which sectors of an existing cold crucible are connected by means of a mica plate and the mica plate is damaged due to arcing and the like and in which the sectors are strongly connected by means of the mica plate and thus are difficult to replace and maintain. A cold crucible, comprising a metal oxide barrier, according to the present invention can prevent arcing, enables reduction of damage on the edge part of a water cooling sector due to a molten material and thus enhances durability. Moreover, the metal oxide barrier can easily be replaced compared to an existing mica plate and thus enables easy maintenance and repair.

Abstract: A method for decommissioning a nuclear facility includes: floating the nuclear reactor pressure vessel above the cavity; rotating the reactor pressure vessel so that the upper portion of the nuclear reactor pressure vessel is closer to the bio-protective concrete than the lower portion; mounting the upper portion of the nuclear reactor pressure vessel on the neighboring upper surface of the bio-protective concrete; and cutting and decommissioning the nuclear reactor pressure vessel mounted on the neighboring upper surface.