Patent Number: 
Section: claims

1. An integrated passive cooling containment structure for a nuclear reactor, the integrated passive cooling containment structure comprising:a concentric arrangement of an inner steel cylindrical shell and an outer steel cylindrical shell, an inner surface of the inner steel cylindrical shell defining a lateral boundary of a containment environment of the nuclear reactor that is configured to accommodate the nuclear reactor, an outer surface of the inner steel cylindrical shell and an inner surface of the outer steel cylindrical shell defining inner and outer diameters, respectively, of an annular gap space between the inner steel cylindrical shell and the outer steel cylindrical shell;a concrete donut structure at a bottom of the annular gap space, such that the concrete donut structure fills a lower region of the annular gap space that is between the outer steel cylindrical shell and the inner steel cylindrical shell and extends upwards into the annular gap space from the bottom of the annular gap space; anda plurality of concrete columns spaced apart azimuthally around a circumference of the annular gap and extending in parallel from a top surface of the concrete donut structure to a top of the annular gap space;wherein the outer steel cylindrical shell, the inner steel cylindrical shell, the plurality of concrete columns, and the concrete donut structure at least partially define one or more coolant channels in the annular gap space, the one or more coolant channels extending from the top surface of the concrete donut structure to the top of the annular gap space,wherein the outer steel cylindrical shell includes one or more coolant supply ports at a bottom of the one or more coolant channels, the one or more coolant supply ports configured to couple with a coolant source via one or more coolant fluid supply conduits, such that the one or more coolant supply ports are configured to direct a coolant fluid into a bottom region of the one or more coolant channels such that the coolant fluid rises through the one or more coolant channels towards a top of the one or more coolant channels, according to a change in coolant fluid buoyancy based on the coolant fluid absorbing heat rejected from the nuclear reactor in the containment environment via the inner steel cylindrical shell. 2. The integrated passive cooling containment structure of claim 1, whereintwo or more concrete columns, of the plurality of concrete columns, each have a radial diameter, in a radial direction of the annular gap space, that equals a radial distance of the annular gap space between an inner diameter and an outer diameter of the annular gap space over at least a portion of a vertical height of each of the two or more concrete columns, such that the two or more concrete columns azimuthally partition at least a portion of the annular gap space into two or more isolated coolant channels that extend vertically through at least the portion of the annular gap space, andthe outer steel cylindrical shell includes two or more coolant supply ports that are each configured to direct coolant fluid into a separate coolant channel of the two or more isolated coolant channels. 3. The integrated passive cooling containment structure of claim 2, further comprising:one or more steel partitions isolating a concrete column of the plurality of concrete columns from an adjacent coolant channel of the one or more coolant channels. 4. The integrated passive cooling containment structure of claim 1, whereinone or more concrete columns, of the plurality of concrete columns, have a radial diameter, in a radial direction of the annular gap space, that is less than a radial distance of the annular gap space between an inner diameter and an outer diameter of the annular gap space, such that the one or more concrete columns are isolated from directly contacting one or more of the inner steel cylindrical shell or the outer steel cylindrical shell. 5. The integrated passive cooling containment structure of claim 1, further comprising:a cap structure that seals the top of the annular gap space to define the top of the one or more coolant channels, the cap structure including one or more coolant outlet ports configured to direct coolant flowing to the top of the one or more coolant channels to a coolant return via one or more coolant return conduits. 6. The integrated passive cooling containment structure of claim 1, wherein the plurality of concrete columns and the concrete donut structure are a single, uniform piece of concrete. 7. The integrated passive cooling containment structure of claim 1, wherein the plurality of concrete columns and the concrete donut structure each include self-consolidating concrete. 8. The integrated passive cooling containment structure of claim 1, wherein the inner steel cylindrical shell and the outer steel cylindrical shell each include corrosion resistant steel or steel coated with a corrosion resistant coating. 9. A method for forming the integrated passive cooling containment structure of claim 1, the method comprising:forming a steel annulus structure, the steel annulus structure including a concentric arrangement of an inner steel cylindrical shell and an outer steel cylindrical shell, an inner surface of the inner steel cylindrical shell defining a lateral boundary of a containment environment of a nuclear reactor, an outer surface of the inner steel cylindrical shell and an inner surface of the outer steel cylindrical shell defining inner and outer diameters, respectively, of an annular gap space between the inner steel cylindrical shell and the outer steel cylindrical shell;forming a concrete donut structure at a bottom of the annular gap space, such that the concrete donut structure fills a lower region of the annular gap space;forming a plurality of concrete columns spaced apart azimuthally around a circumference of the annular gap space and extending in parallel from a top surface of the concrete donut structure to a top of the annular gap space, such that the outer steel cylindrical shell, the inner steel cylindrical shell, the plurality of concrete columns, and the concrete donut structure at least partially define one or more coolant channels in the annular gap space, the one or more coolant channels extending from the top surface of the concrete donut structure to the top of the annular gap space; andinstalling one or more coolant supply ports at a bottom of the one or more coolant channels, the one or more coolant supply ports configured to couple with a coolant source via one or more coolant fluid supply conduits, such that the one or more coolant supply ports are configured to direct a coolant fluid into a bottom region of the one or more coolant channels such that the coolant fluid rises through the one or more coolant channels towards a top of the one or more coolant channels, according to a change in coolant fluid buoyancy based on the coolant fluid absorbing heat rejected from the nuclear reactor in the containment environment via the inner steel cylindrical shell. 10. The method of claim 9, whereinthe forming the steel annulus structure includes installing one or more steel partitions in the annular gap space to define an inner laterally-closed space, that extends from the top surface of the concrete donut structure to the top of the annular gap space, within the annular gap space, andthe forming the plurality of concrete columns includes filling the inner laterally-closed space with concrete to form one concrete column of the plurality of concrete columns. 11. The method of claim 9, further comprising:mounting the nuclear reactor in the containment environment such that the nuclear reactor is structurally supported in the containment environment by the integrated passive cooling containment structure via at least the concrete donut structure. 12. A nuclear plant, comprising:a reactor building structure;the integrated passive cooling containment structure of claim 1, wherein the integrated passive cooling containment structure is located within an interior of the reactor building structure and defines a void space between the reactor building structure and an exterior of the integrated passive cooling containment structure; anda nuclear reactor located within the containment environment that is at least partially defined by the inner surface of the inner steel cylindrical shell of the integrated passive cooling containment structure. 13. The nuclear plant of claim 12, whereinthe integrated passive cooling containment structure further includes a cap structure that seals the top of the annular gap space to define the top of the one or more coolant channels, the cap structure including one or more coolant outlet ports configured to direct coolant flowing to the top of the one or more coolant channels to a coolant return via one or more coolant return conduits; andthe nuclear plant further includes a coolant reservoir that is both the coolant source and the coolant return.