US 2004/0202273 A1 · Method and compositions for grouting decommissioned nuclear reactor components

Abstract

A method for grouting a decommissioned nuclear reactor containing residual water. A first, water-absorbent grout is used to grout the bottom portion of the reactor vessel. The water-absorbent grout is formed of cement and a water-absorbent particulate material, such as expanded perlite, exfoliated vermiculite or granulated bentonite. Excess water is absorbed by the particulate material, so that the residual water is incorporated in the fill material when it sets. A set retarder may be included to extend the time for uptake of residual water by the particulate material. Foam may also be included to reduce density and increase pumpability. The remaining, upper portion of the reactor vessel is grouted using lightweight cellular cement grout, lacking the water-absorbent particulate material, so that total weight of the fill remains low enough that the grouted vessel can be removed using the facility's installed crane system. Because the residual water is incorporated in the first, water-absorbent grout, the problem of residual water causing dissipation and collapse of the bubble structure in the lightweight cellular cement grout is obviated.

Claims15

Dependent claims

A method for grouting a decommissioned reactor vessel without exceeding a predetermined weight limit for lifting, said reactor vessel having residual water in a bottom portion thereof, said method comprising the steps of:

forming a water-absorbent cement grout by mixing:
a cement slurry;
and
a water-absorbent particulate material;
and
flowing said cement grout into said bottom portion of said reactor vessel so that said water-absorbent particulate material absorbs excess water from said cement grout as said grout intermixes with said residual water.

3 more elements

A method for grouting a decommissioned reactor vessel without exceeding a predetermined weight limit for lifting, said reactor vessel having a predetermined amount of residual water in a bottom portion thereof, said method comprising the steps of:

forming a first, water-absorbent cement grout by mixing:
a cement slurry;
and
a water-absorbent particulate material;
flowing a selected amount of said water-absorbent cement grout into said bottom portion of said reactor vessel so that said water-absorbent particulate material absorbs excess water from said grout as said grout intermixes with said residual water;
said selected amount of said water-absorbent cement grout being limited to an amount approximately sufficient to fully absorb said predetermined amount of residual water in said reactor vessel;
allowing said first, water-absorbent cement grout to set so as to form a first layer of cementitious fill that incorporates said residual water;
forming a second, lightweight cellular cement grout by mixing:
a cement slurry;
and
a cellular foam material;
flowing said lightweight cellular cement grout into said reactor vessel atop said first layer of cementitious fill in which said residual water has been incorporated;
and
allowing said second, lightweight cellular cement grout to set so as to form a second, relatively lighter layer of cementitious fill in an upper portion of said vessel, so that combined weight of said cementitious fills remains sufficiently low that total weight of said reactor vessel remains within said predetermined weight limit for lifting.

11 more elements

Dependencies are inferred from the claim text.

Method and compositions for grouting decommissioned nuclear reactor components

Life of this patent

Method and compositions for grouting decommissioned nuclear reactor components

Life of this patent

Abstract

Claims15