# US 12,112,856 B2 · Spent nuclear fuel storage rack system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,112,856 B2 - Document ID: US12112856B2 - Status: Granted - Kind: B2 - Application number: 17/973,895 - Filed: 2022-10-26 - Published: 2023-04-27 - Granted: 2024-10-08 - Earliest claimed: 2021-10-26 - Assignees: Holtec International - Applicants: Holtec International - Inventors: Krishna P. Singh; Stephen J. Agace - Web page: https://patentgrep.com/patent/US12112856B2 ## CPC - G21C 19/07: Storage racks; Storage pools - G21C 19/40: Arrangements for preventing occurrence of critical conditions, e.g. during storage - Y02E 30/30: Nuclear fission reactors - G21C: NUCLEAR REACTORS (fusion reactors, hybrid fission-fusion reactors G21B; nuclear explosives G21J) - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A fuel rack for storing nuclear fuel in a fuel pool in one embodiment comprises a baseplate configured for placement in a fuel pool, and a cellular body coupled to the baseplate. The body comprises tightly-packed upwardly open cells which each hold a nuclear fuel assembly. In one embodiment, each cell may have a hexagonal cross-sectional configuration. The cells are each formed by angled cell walls and corners formed between adjoining cell walls. Adjacent cells are arranged to meet in corner-to-corner alignment. This produces triangular-shaped flux traps interspersed between the cells for reactivity control. In some embodiments, at least one peripheral side of the fuel rack has an undulating configuration defining a series of alternating peaks and valleys which nests with a complementary configured peripheral side of an adjacent fuel rack. This provides higher packing density of fuel racks and fuel assemblies in the fuel pool. ## Claims ### Claim 1 A fuel rack for storing spent nuclear fuel comprising: a baseplate; and a cellular body coupled to the baseplate and comprising a plurality of open cells, each cell having a hexagonal configuration to receive a fuel assembly therein, each cell being formed by a plurality of angled cell walls and corners formed between adjoining cell walls; wherein the cells are arranged so that the corners of each cell directly abuttingly engage only the corners of any adjacent cell of the cellular body so as to define a triangular flux trap on each side of the directly abuttingly engaged corners. ### Claim 2 (depends on 1) The fuel rack according to claim 1, wherein each cell is vertically elongated and configured to hold a single fuel assembly. ### Claim 3 (depends on 2) The fuel rack according to claim 2, wherein each corner of each cell is formed by an oblique intersection of a pair of the cell walls. ### Claim 4 (depends on 1) The fuel rack according to claim 1, wherein each cell wall defines a flat outer face between a pair of corners, and cell walls of the fuel rack do not meet in a face-to-face alignment. ### Claim 5 (depends on 1) The fuel rack according to claim 1, further comprising at least one neutron absorbing apparatus inserted inside each cell. ### Claim 6 (depends on 5) The fuel rack according to claim 5, wherein the at least one neutron absorber apparatus comprising a plurality of boron-containing plates, each plate being affixed to one of the cell walls. ### Claim 7 (depends on 6) The fuel rack according to claim 6, wherein the boron-containing plates each have a length substantially coextensive with a height of the cell walls. ### Claim 8 (depends on 1) The fuel rack according to claim 1, wherein the cells are formed by a plurality of individual hexagonal tubes fixedly coupled to the baseplate. ### Claim 9 (depends on 8) The fuel rack according to claim 8, wherein perimeter tubes arranged around lateral sides of the fuel rack define outwardly open triangular recesses forming flux traps. ### Claim 10 (depends on 1) The fuel rack according to claim 1, wherein the triangular flux traps on each side of the directly abuttingly engaged corners defines a plurality of triangular flux traps interspersed between and separating the cells in the fuel rack. ### Claim 11 (depends on 10) The fuel rack according to claim 10, wherein at least some of the interior cells of the fuel rack are separated from adjacent cells by a pair of triangular flux traps. ### Claim 12 (depends on 1) The fuel rack according to claim 1, wherein the cells are arranged in a plurality of laterally extending linear rows on the baseplate, and the cells in one row are laterally offset from the cells in adjacent rows. ### Claim 13 (depends on 1) The fuel rack according to claim 1, wherein a first peripheral side of the baseplate comprises an undulating configuration defining a series of alternating peaks and valleys. ### Claim 14 (depends on 13) The fuel rack according to claim 13, wherein the first peripheral side has sawtooth configuration, the peaks and valleys being V-shaped. ### Claim 15 (depends on 13) The fuel rack according to claim 13, wherein the valleys of the first peripheral side are configured to receive peaks of a mating second baseplate having a peripheral side with an undulating configuration. ### Claim 16 (depends on 13) The fuel rack according to claim 13, wherein a second peripheral side of the baseplate opposite the first peripheral side also comprises an undulating configuration defining a series of alternating peaks and valleys. ### Claim 17 (depends on 1) The fuel rack according to claim 1, wherein the cells are formed by a plurality of interlocking and intersecting slotted plates. ### Claim 18 (depends on 17) The fuel rack according to claim 17, wherein the slotted plates comprise a first and second set of slotted plates each oriented obliquely to peripheral sides of the baseplate, and a third set of slotted plates arranged perpendicularly to two opposing peripheral sides of the baseplate. ### Claim 19 (depends on 18) The fuel rack according to claim 18, wherein the first, second, and third sets of slotted plates do not intersect each other orthogonally. ### Claim 20 A fuel rack for storing spent nuclear fuel comprising: a baseplate; a cellular body formed by a plurality of vertically elongated hexagonal tubes extending upwards from the baseplate; the tubes defining an array of hexagonal-shaped open cells each configured to receive a fuel assembly therein, each of the tubes comprising a plurality of obliquely angled cell walls in which contiguous adjoining cell walls meet at corners, each tube comprising a plurality of corners; the corners of each tube directly abuttingly contacting corners of adjacent tubes in the array such that a pair of triangular spaces defining flux traps are formed by the cell walls between the adjacent tubes at the directly abuttingly contacting corners. ### Claim 21 (depends on 20) The fuel rack according to claim 20, wherein a first one of the pair of triangular spaces is formed on a first side of the corners in abutting contact between the adjacent tubes, and a second one of the pair of triangular spaces is formed on a second side of the corners in abutting contact between the adjacent tubes. ### Claim 22 (depends on 20) The fuel rack according to claim 20, wherein the array of open cells is a staggered array in which the tubes are arranged in a series of rows and columns on the baseplate, the tubes in each row being laterally offset from the tubes in adjacent rows, and the tubes in each column being laterally offset from the tubes in adjacent columns.