# US 10,872,706 B2 · Apparatus for passively cooling a nuclear plant coolant reservoir > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,872,706 B2 - Document ID: US10872706B2 - Status: Granted - Kind: B2 - Application number: 14/195,878 - Filed: 2014-03-04 - Published: 2020-10-22 - Granted: 2020-12-22 - Earliest claimed: 2013-03-14 - Assignees: Westinghouse Electric Corp. - Applicants: Westinghouse Electric Company LLC - Inventors: Lawrence E. Conway; Gary L. Sedlacek - Web page: https://patentgrep.com/patent/US10872706B2 ## CPC - G21C 19/07: Storage racks; Storage pools - G21D 1/02: Arrangements of auxiliary equipment - G21C 15/18: Emergency cooling arrangements; Removing shut-down heat - Y02E 30/00: Energy generation of nuclear origin - Y02E 30/30: Nuclear fission reactors - G21C: NUCLEAR REACTORS (fusion reactors, hybrid fission-fusion reactors G21B; nuclear explosives G21J) - G21D: NUCLEAR POWER PLANT - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A passive cooling system for cooling the in-containment refueling water storage tank and the spent fuel pool of nuclear power plants that can extend the number of days the plants can safely be maintained without operator intervention. The cooling system employs a thermosiphon in a closed loop cycle that circulates a refrigerant around the cooling loop between heat exchangers within the spent fuel and in-containment refueling water and the ambient atmosphere outside the containment, by natural circulation. ## Claims ### Claim 1 A nuclear power plant, comprising: a nuclear steam supply system; a containment system comprising a containment enclosure for hermetically housing the nuclear steam supply system; an annulus adjacent an exterior surface of the containment enclosure; a reservoir comprising water, wherein the reservoir is housed within or within proximity of the containment enclosure; spent nuclear fuel submerged within the reservoir and cooled by the water; and a thermosiphon extending from within the reservoir to an exterior of the containment enclosure for transferring heat in the reservoir to air outside of the containment enclosure, wherein the thermosiphon comprises: a first heat exchanger at least partially submerged in the water, and a second heat exchanger thermally coupled to the first heat exchanger, wherein the second heat exchanger comprises an air-cooled heat exchanger positioned within the annulus. ### Claim 2 (depends on 1) The nuclear power plant of claim 1 wherein: the second heat exchanger is at a higher elevation than the first heat exchanger; the water on a first side of the first heat exchanger is in thermal communication with a working fluid on a second side of the first heat exchanger; the second side of the first heat exchanger is in fluid communication with a first side of the second heat exchanger through a closed loop in which the working fluid circulates; and the working fluid on the first side of the second heat exchanger is in thermal communication with ambient air outside the containment enclosure on a second side of the second heat exchanger. ### Claim 3 (depends on 2) The nuclear power plant of claim 2 wherein the working fluid is a refrigerant. ### Claim 4 (depends on 3) The nuclear power plant of claim 3 wherein the refrigerant is 245fa. ### Claim 5 (depends on 2) The nuclear power plant of claim 2 wherein a portion of the closed loop outside the containment enclosure comprises a finned tube. ### Claim 6 (depends on 2) The nuclear power plant of claim 2 wherein the containment enclosure comprises a steel shell having substantially vertical walls that extend from a lower portion of the containment system to an upper portion of the containment system. ### Claim 7 (depends on 6) The nuclear power plant of claim 6 including an air baffle extending substantially around and spaced from the vertical walls of the containment enclosure with an air inlet at a lower elevation of the air baffle and an air outlet at an upper elevation of the air baffle, the second heat exchanger being supported within an annulus between the vertical wall of the containment enclosure and the air baffle. ### Claim 8 (depends on 7) The nuclear power plant of claim 7 wherein the second heat exchanger is supported in a lower portion of the annulus or outside the containment. ### Claim 9 (depends on 2) The nuclear power plant of claim 2 wherein the first heat exchanger includes a plurality of first heat exchangers, the second heat exchanger includes a plurality of second heat exchangers and the closed loop includes a plurality of closed loops operating in parallel with each of the closed loops having at least one of the first heat exchangers and at least one of the second heat exchangers. ### Claim 10 (depends on 9) The nuclear power plant of claim 9 wherein each of the second heat exchangers are spaced around the outside of the containment. ### Claim 11 (depends on 2) The nuclear power plant of claim 2 wherein the closed loop includes a valve for cutting off circulation of the working fluid. ### Claim 12 (depends on 1) The nuclear power plant of claim 1 wherein the reservoir is a refueling water storage tank within the containment and the first heat exchanger is within the containment and the second heat exchanger is outside the containment. ### Claim 13 (depends on 1) The nuclear power plant of claim 1 wherein the reservoir is a spent fuel pool outside of and within proximity of the containment enclosure.