CONSTRUCTING METHOD FOR DELAYING CORROSION OF RADIOACTIVE WASTE DISPOSAL CONTAINER IN CONCRETE DISPOSAL VAULT

Abstract

The present invention relates to a constructing method for delaying corrosion of radioactive waste disposal container in concrete disposal vault and, more specifically, to a constructing method for delaying corrosion of radioactive waste disposal container in concrete disposal vault in which backfill, placed to the top, combines pH control capsules, thereby dissolving the pH control capsules in rainwater, and a pH controller, inside, is discharged, thereby preventing decrease of pH of the backfill below 8.5 and delaying corrosion in the disposal containers, upon filling in backfill after placing radioactive waste disposal containers in the concrete vault.

Claims

1. A constructing method for delaying corrosion of radioactive waste disposal container in concrete disposal vault, comprising: a disposal containers stacking process wherein disposal containers in which radioactive waste is stored are mutually spaced on the surface of a concrete vault, thereby stacking more than one layer; a backfill filling process wherein backfill is filled in the top of the disposal containers, wherein more than one layer is stacked; a repetitive process wherein a space is formed on the top of the concrete vault by repeating the stacking of the disposal containers and backfilling when the backfill is completely cured; a pH control backfill filling process wherein pH control backfill combining pH control capsules is filled and cured in the space formed to the top of the concrete vault; and a cover stacking process wherein a concrete cover is stacked to the top of the concrete vault for sealing.

2. The constructing method for delaying corrosion of radioactive waste disposal container in concrete disposal vault according to claim 1, wherein the pH control capsules are equipped with alkali metal powder inside and are made up of water-soluble cellulose ether shells for dissolving in rainwater and discharging the alkali metal powder.

3. The constructing method for delaying corrosion of radioactive waste disposal container in concrete disposal vault according to claim 1, wherein widths are all manufactured differently, thereby getting dissolved at different times.

4. The constructing method for delaying corrosion of radioactive waste disposal container in concrete disposal vault according to claim 1, wherein the pH control capsules maintains the pH of the backfill more than pH8.6 in which the disposal containers are not corroded.

5. The constructing method for delaying corrosion of radioactive waste disposal container in concrete disposal vault according to claim 2, wherein the alkali metal powder combines any one or more than two of sodium (Na), potassium (K), lithium (Li), rubidium (Rb), cesium (Cs) and francium (Fr).

Description

DESCRIPTION OF DRAWINGS

[0018] FIG. 1 illustrates a graph for explaining that a pH of Portland cement concrete is generally decreased due to rainwater for a long time.

[0019] FIG. 2 illustrates a graph for explaining a pH corroded in a disposal container.

[0020] FIG. 3 illustrates a process drawing for explaining a constructing method for delaying corrosion of radioactive waste disposal container in concrete disposal vault according to the present invention.

[0021] FIGS. 4 to 8 illustrate explanation drawings for the constructing method for delaying corrosion of radioactive waste disposal container in concrete disposal vault according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The configuration of a constructing method for delaying corrosion of radioactive waste disposal container in concrete disposal vault of the present invention will be described in detail with the accompanying drawings.

[0023] In the following description of the present invention, a detailed description of known incorporated functions and configurations will be omitted when to include them would make the subject matter of the present invention rather unclear. Also, the terms used in the following description are defined taking into consideration the functions provided in the present invention.

[0024] The definitions of these terms should be determined based on the whole content of this specification, because they may be changed in accordance with the option of a user or operator or a usual practice.

[0025] FIG. 3 illustrates a process drawing for explaining a constructing method for delaying corrosion of radioactive waste disposal container in concrete disposal vault according to the present invention, and FIGS. 4 to 8 illustrate explanation drawings for the constructing method for delaying corrosion of radioactive waste disposal container in concrete disposal vault according to the present invention.

[0026] Referring to FIGS. 3 to 8, a constructing method for delaying corrosion of radioactive waste disposal container in concrete disposal vault according to the present invention consists of a disposal container stacking process (S10), a backfill filling process (S20), a repetitive process (S30), a pH control backfill filling process (S40) and a cover staking process (S50).

[0027] <<Disposal Containers Stacking Process-S10>>

[0028] First, as illustrated in FIG. 4, disposal containers (3) in which radioactive waste is stored are mutually spaced on the surface of a prefabricated concrete vault (1), thereby stacking more than one layer. Hereinafter, the concrete mixing conditions in the concrete vault (1) are design strength (91 days, psi): 5500, the maximum water binder ratio: 35%, the maximum size of coarse aggregate: 25 mm, admixture: fly-ash, water: 247 lb/cy, cement: 578 lb/cy, fly-ash: 145 lb/cy, coarse aggregate: 1692 lb/cy, fine aggregate: 1216 lb/cy.

[0029] <<Backfill Filling Process-S20>>

[0030] When stacking the disposal containers (3) is complete, as illustrated in FIG. 5, backfill (M1) is filled in the top of the disposal containers (3), wherein more than one layer is stacked. Hereinafter, the backfill (M1) mixing conditions are design strength (91 days, psi): 5500, the maximum water binder ratio: 35%, the maximum size of coarse aggregate: 25 mm, admixture: fly-ash, water: 247 lb/cy, cement: 578 lb/cy, fly-ash: 145 lb/cy, coarse aggregate: 1692 lb/cy, fine aggregate: 1216 lb/cy.

[0031] <<Repetitive Process-S30>>

[0032] When the backfill (M1) is completely cured, as illustrated in FIG. 6, by means of consecutive repetition of the disposal containers stacking process (S10) and the backfill filling process (S20), the disposal containers (3) are stacked to the height of the concrete vault (1) and then, the backfill (M1) is filled. Hereinafter, upon filling the backfill (M1), a certain space (e.g., a height of 10-50 cm) is formed on the top of the concrete vault (1).

[0033] <<pH Control Backfill Filling Process-S40>>

[0034] As soon as the backfill (M1) is filled, as illustrated on FIG. 7, pH control backfill (M2) combining pH control capsules (C) is filled and cured in the space formed to the top of the concrete vault (1).

[0035] Further, it is desirable that the pH control capsules (c) are equipped with alkali metal powder inside and are made up of water-soluble cellulose ether shells for dissolving in rainwater and discharging the alkali metal powder (P). Also, it is desirable that widths are all manufactured differently, thereby getting dissolved at different times.

[0036] Further, the pH control capsules (c) maintains the pH of the backfill (M1) more than pH8.6 in which the disposal containers (3) are not corroded, and the alkali metal powder (P) combines any one or more than two of sodium (Na), potassium (K), lithium (Li), rubidium (Rb), cesium (Cs) and francium (Fr).

[0037] <<Cover Staking Process-S50>>

[0038] When the backfill (M1) and the pH control backfill (M2) on the top are completely cured, as illustrated in FIG. 8, a concrete cover (5) is stacked to the top of the concrete vault (1) for sealing. Hereinafter, it may be possible to delay the timing of dissolving the pH control capsules (C) in rainwater more by installing biodegradable films (not illustrated) on the upper side of the pH control backfill (M2) prior to the stacking of the concrete cover (5).

[0039] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

TABLE-US-00001 <Explanations of numeral reference> 1 : concrete vault 3 : disposal containers 5 : concrete cover C : pH control capsules M1 : backfill M2 : pH control backfill P : alkali metal powder