Method for decommissioning heavy water reactor facility

Patent metadata

Field	Value
Publication number	US-11984233-B2
Application number	US-201917259691-A
Country	US
Kind code	B2
Filing date	Jul 3, 2019
Priority date	Jul 13, 2018
Publication date	May 14, 2024
Grant date	May 14, 2024

Abstract

A method for decommissioning a heavy water reactor facility includes: removing the plurality of guide tubes from a plurality of through-holes; installing a plurality of shielding stoppers in the plurality of through-holes; removing the shielding stopper installed in one through-hole of the plurality of through-holes, and inserting a cutting device into a lower portion of the reactivity mechanism deck through the one through-hole to cut a connection portion between the reactivity mechanism deck and the calandria vault by using the cutting device; and separating the reactivity mechanism deck from the calandria vault.

First claim

The invention claimed is:

1. A method for decommissioning a heavy water reactor facility that includes a calandria, a calandria vault accommodating the calandria, a reactivity mechanism deck supported by the calandria vault to be located at an upper portion of the calandria and including a plurality of through-holes, and a plurality of guide tubes connected to the calandria through the plurality of through-holes, comprising:
removing the plurality of guide tubes from the plurality of through-holes;
installing a plurality of shielding stoppers in the plurality of through-holes;
removing the shielding stopper installed in a first through-hole of the plurality of through-holes;
inserting a cutting device into a lower portion of the reactivity mechanism deck through the first through-hole;
cutting a connection portion between the reactivity mechanism deck and the calandria vault by using the cutting device; and
separating the reactivity mechanism deck from the calandria vault,
wherein
the cutting of the connection portion between the reactivity mechanism deck and the calandria vault by using the cutting device includes
installing a first shielding ring between the first through-hole and the cutting device.

2. The method for decommissioning the heavy water reactor facility of claim 1 , wherein
the cutting of the connection portion between the reactivity mechanism deck and the calandria vault by using the cutting device is performed by cutting a seal plate welded between a liner plate positioned on an inner wall of the calandria vault and the reactivity mechanism deck.

3. The method for decommissioning the heavy water reactor facility of claim 2 , wherein
the heavy water reactor facility further includes a seismic restraint positioned between the reactivity mechanism deck and the calandria and connected to the liner plate of the calandria vault, and
the method for decommissioning the heavy water reactor facility further includes separating the seismic restraint from the liner plate by using the cutting device.

4. The method for decommissioning the heavy water reactor facility of claim 1 , further comprising:
removing a shielding stopper installed in a second through-hole among the plurality of through-holes;
inserting a camera device into a lower portion of the reactivity mechanism deck through the second through-hole; and
checking a lower space of the reactivity mechanism deck by using the camera device.

5. The method for decommissioning the heavy water reactor facility of claim 4 , wherein
the checking of the lower space of the reactivity mechanism device by using the camera device includes
installing a second shielding ring between the second through-hole and the camera device.

6. The method for decommissioning the heavy water reactor facility of claim 1 , wherein
the separating of the reactivity mechanism deck from the calandria vault includes:
lifting the reactivity mechanism deck from the calandria vault by using a crane;
installing a platform on an upper portion of the calandria vault;
installing a carrier roller on an upper portion of the platform; and
mounting the reactivity mechanism deck on the carrier roller to move it.

Assignees

• Korea Hydro & Nuclear Power Co

Inventors

• Hwang Seok-Ju
• Hwang Young Hwan
• Cho Hang-Rae
• Kim Cheon-Woo

Classifications

• G21D1/003 Primary

  Nuclear facilities decommissioning arrangements (decontamination arrangements, treating radioactively contaminated material G21F9/00) · CPC title

• G21F9/008

  Apparatus specially adapted for mixing or disposing radioactively contamined material (G21F9/305 and G21F9/308 take precedence) · CPC title

• G21C13/06 Primary

  Sealing-plugs (for pressure vessels in general F16J13/00) · CPC title

• G21C1/20

  moderator being liquid, e.g. pressure-tube reactor · CPC title

• G21C19/14

  characterised by their adaptation for use with horizontal channels in the reactor core · CPC title