Patent Number: 
Section: claims

1. An underground storage module for vertically-stacked storage of nuclear waste canisters, the storage module comprising:an elongated vertical outer shell defining vertical axis and an internal cavity, the outer shell having a top and a hermetically sealed bottom, the outer shell being disposed below grade for a majority of its height;an elongated inner shell disposed inside the outer shell in the cavity of the outer shell;an annular common inlet air plenum extending circumferentially around a top of the outer shell, the inlet air plenum arranged to draw ambient cooling air through a plurality of air inlets arranged around the outer shell;an annular-shaped vertical downcomer ventilation shaft between the inner and outer shells, the downcomer ventilation shaft arranged to convey the cooling air from the inlet air plenum downwards along the outer shell to a bottom of the cavity;a first canister positioned in the cavity in a lower position;a second canister vertically stacked above the first canister in an upper position;an annular-shaped vertical riser ventilation shaft formed between the inner shell and the canisters, the riser ventilation shaft being in fluid communication with the downcomer ventilation shaft near the bottom of the cavity in the outer shell and arranged to convey cooling air upwards across outer sidewall surfaces of the canisters for removing decay heat; anda removable top lid mounted on top of the outer shell covering the cavity, the top lid in fluid communication with the riser ventilation shaft and configured to form an airflow pathway to atmosphere through the lid from the riser ventilation shaft;wherein the inlet air plenum adjoins an exterior side of the top of the outer shell and extends laterally outwards therefrom;wherein the outer shell includes a plurality of circumferentially spaced apart airflow openings extending laterally between the inlet air plenum and a top of the downcomer ventilation shaft in the cavity, the cooling air entering the downcomer ventilation shaft through the outer shell airflow openings from the inlet air plenum. 2. The storage module of claim 1, wherein the outer and inner shells are cylindrically shaped and concentrically aligned with the vertical axis. 3. The storage module of claim 1, wherein the inner shell includes a plurality of circumferentially spaced apart airflow openings extending between the downcomer ventilation shaft and a bottom of the riser ventilation shaft, the cooling air entering the riser ventilation shaft from the downcomer ventilation shaft through the inner shell airflow openings. 4. The storage module of claim 1, wherein the top lid includes a plurality of radially extending air passages which are in fluid communication with the riser ventilation shaft and a central airflow passageway in the top lid, the air passages and central airflow passageway forming the airflow pathway to atmosphere through the lid. 5. The storage module of claim 4, wherein the top lid includes a diametrically enlarged top portion disposed over and extending radially beyond the outer and inner shells, and a downward extending bottom portion position inside a top of the inner shell. 6. The storage module of claim 5, wherein the top portion of the top lid has a larger diameter than the outer shell and the bottom portion has a smaller diameter than the inner shell forming an annular gap in fluid communication with the riser ventilation shaft and the central airflow passageway in the top lid. 7. The storage module of claim 1, further comprising a concrete top pad circumferentially surrounding a top of the outer shell and a concrete base pad engaging the bottom of the outer shell, the inlet air plenum being disposed and recessed in the top pad. 8. The storage module of claim 7, further comprising a metal cover plate covering the inlet air plenum, wherein the air inlets are formed as openings through the cover plate. 9. The storage module of claim 7, wherein the top pad is square-shaped in top plan view and the inlet air plenum has a rectilinear shape. 10. The storage module of claim 1, further comprising soil filled adjacent to the outer shell and extending between the top pad and the base pad. 11. A system for vertically-stacked underground storage of nuclear waste canisters comprising:an elongated outer shell defining a vertical axis and an internal cavity;a first canister positioned in the cavity in a lower position;a second canister vertically stacked on top of the first canister in an upper position, the first and second canisters being concentrically aligned with the vertical axis;a removable top lid mounted on top of the outer shell and covering the cavity;a bottom plate hermetically sealed to a bottom of the outer shell and covering the cavity;a top of the outer shell embedded in a concrete top pad surrounding the outer shell and a concrete base pad supporting the bottom plate on the outer shell;the concrete top pad defining a recessed common inlet air plenum extending circumferentially around the top of the outer shell;a plurality of air inlets arranged around the top pad and in fluid communication with the inlet air plenum, the inlet air plenum operable to draw ambient cooling air therein through the air inlets;an annular-shaped vertical downcomer ventilation shaft between the inner and outer shells, the downcomer ventilation shaft arranged to convey the cooling air from the inlet air plenum downwards along the outer shell to a bottom of the cavity. 12. The system of claim 11, further comprising an annular-shaped vertical riser ventilation shaft formed between the inner shell and the canisters, the riser ventilation shaft being in fluid communication with the downcomer ventilation shaft near the bottom of the outer shell and arranged to convey cooling air upwards across outer sidewall surfaces of the canisters for removing decay heat. 13. The system of claim 11, further comprising soil filled adjacent to the outer shell and extending vertically between the top pad and the base pad. 14. The system of claim 11, further comprising a centering and spacing ring assembly interspersed between the first and second canisters configured to form an airflow pathway therebetween in fluid communication with the riser ventilation shaft. 15. The system of claim 11, further comprising a top lid including a plurality of radially extending air passages which are in fluid communication with the riser ventilation shaft and a central airflow passageway in the top lid, the air passages and central airflow passageway forming the airflow pathway to atmosphere through the lid. 16. The system of claim 15, wherein the top lid includes a diametrically enlarged upper portion disposed over the outer and inner shells and a downward extending bottom protrusion positioned inside an open top of the inner shell. 17. The system of claim 16, wherein the upper portion of the top lid has a larger diameter than the outer shell and the bottom protrusion has a smaller diameter than the inner shell. 18. An underground storage module for vertically-stacked storage of nuclear waste canisters, the storage module comprising:an elongated vertical outer shell defining a vertical axis and an internal cavity, the outer shell having a top and a hermetically sealed bottom, the outer shell being disposed below grade for a majority of its height;an elongated inner shell disposed inside the outer shell and cavity;a first canister positioned in the cavity in a lower position;a second canister vertically stacked above the first canister in an upper position, the first and second canisters being concentrically aligned with the vertical axis;an annular common inlet air plenum extending circumferentially around a top of the outer shell, the inlet air plenum arranged to draw inwards ambient cooling air through a plurality of air inlets in fluid communication with the inlet air plenum;an annular-shaped vertical downcomer ventilation shaft formed between the inner and outer shells, the downcomer ventilation shaft arranged to convey the cooling air from the inlet air plenum downwards along the outer shell to a bottom of the cavity;an annular-shaped vertical riser ventilation shaft formed between the inner shell and the canisters, the riser ventilation shaft being in fluid communication with the downcomer ventilation shaft near the bottom of the cavity of the outer shell and arranged to convey cooling air upwards across outer sidewall surfaces of the canisters for removing decay heat; anda removable top lid mounted on top of the outer shell covering the cavity, the top lid including a diametrically enlarged top portion extending radially outward beyond the outer shell and a bottom portion extending downward from the top portion into an open top end of the inner shell, the top and bottom portions spaced vertically apart defining a plurality of radial air passages which are in fluid communication with the riser ventilation shaft and a central airflow passageway extending through the top portion of the lid;a top of the outer shell being embedded in a concrete top pad surrounding the outer shell, the concrete top pad defining the common inlet air plenum which is recessed in the concrete top pad and extends circumferentially around the top of the outer shell;a plurality of air inlets arranged around the concrete top pad in fluid communication with the inlet air plenum, the inlet air plenum operable to draw ambient cooling air therein through the air inlets;wherein the radial air passages and central airflow passageway form an airflow pathway to atmosphere through the lid. 19. An underground storage module for vertically-stacked storage of nuclear waste canisters, the storage module comprising:an elongated vertical outer shell defining vertical axis and an internal cavity, the outer shell having a top and a hermetically sealed bottom, the outer shell being disposed below grade for a majority of its height;an elongated inner shell disposed inside the outer shell in the cavity of the outer shell;an annular common inlet air plenum extending circumferentially around a top of the outer shell, the inlet air plenum arranged to draw ambient cooling air through a plurality of air inlets arranged around the outer shell;a concrete top pad circumferentially surrounding a top of the outer shell and a concrete base pad engaging the bottom of the outer shell, the inlet air plenum being disposed and recessed in the top pad;an annular-shaped vertical downcomer ventilation shaft between the inner and outer shells, the downcomer ventilation shaft arranged to convey the cooling air from the inlet air plenum downwards along the outer shell to a bottom of the cavity;a first canister positioned in the cavity in a lower position;a second canister vertically stacked above the first canister in an upper position;an annular-shaped vertical riser ventilation shaft formed between the inner shell and the canisters, the riser ventilation shaft being in fluid communication with the downcomer ventilation shaft near the bottom of the cavity in the outer shell and arranged to convey cooling air upwards across outer sidewall surfaces of the canisters for removing decay heat; anda removable top lid mounted on top of the outer shell covering the cavity, the top lid in fluid communication with the riser ventilation shaft and configured to form an airflow pathway to atmosphere through the lid from the riser ventilation shaft.