# US 2021/0280332 A1 · Passive cooling device for casks containing nuclear fuel

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- Number: US 2021/0280332 A1
- Document ID: US20210280332A1
- Status: Published application
- Kind: A1
- Application number: 16/779,908
- Filed: 2020-02-03
- Published: 2021-09-09
- Earliest claimed: 2019-02-01
- Assignees: Holtec International
- Applicants: Holtec International
- Inventors: Krishna P. SINGH
- Web page: https://patentgrep.com/patent/US20210280332A1

## CPC

- G21F 5/10: Heat-removal systems, e.g. using circulating fluid or cooling fins
- G21C 13/02: Details
- G21C 19/07: Storage racks; Storage pools
- G21C 19/08: Means for heating fuel elements before introduction into the core; Means for heating or cooling fuel elements after removal from the core
- G21C 19/40: Arrangements for preventing occurrence of critical conditions, e.g. during storage
- G21F 5/00: Transportable or portable shielded containers
- G21F 5/002: Containers for fluid radioactive wastes
- G21F 5/008: Containers for fuel elements
- G21F 5/012: Fuel element racks in the containers
- G21F 5/06: Details of, or accessories to, the containers
- G21F 5/12: Closures for containers; Sealing arrangements
- G21F 5/14: Devices for handling containers or shipping-casks, e.g. transporting devices {loading and unloading, filling of containers (cranes, load-engaging elements or devices for cranes, capstans, winches or tackles B66C)}
- Y02E 30/30: Nuclear fission reactors
- G21F: PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR (radiation protection by pharmaceutical means A61K8/00, A61Q17/04; in cosmonautic vehicles B64G1/54; combined with a reactor G21C11/00; combined with X-ray tubes H01J35/16; combined with X-ray apparatus H05G1/02)
- 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 system for externally cooling a cask containing heat-emitting spent nuclear fuel includes the cask comprising a radiation shielding body defining an internal cavity configured to hold a canister containing the spent nuclear fuel. A continuously annular cooling jacket extends circumferentially around an external surface of the cask body. The cooling jacket may have a double shell construction including an internal cavity for a cooling medium which provides an external heat sink for absorbing heat radiated from the external wall surface of the cask generated by the spent nuclear fuel. The heat emitted by the spent nuclear fuel is absorbed by the cooling medium in the cooling jacket, thereby in turn cooling the cask. In one embodiment, the cooling medium may be dry ice which undergoes sublimation by absorbing the heat to change from solid to gaseous phase directly. The jacket may be formed of multiple segments.

## Claims

### Claim 1

A system for cooling high level radioactive waste, the system comprising:
a cask comprising a storage cavity containing the high level radioactive waste emitting heat; and
a cooling jacket at least partially surrounding the cask, the cooling jacket comprising a cooling medium cavity containing a cooling medium that sublimates at normal atmospheric pressure, the cooling medium providing an external heat sink for absorbing the heat emitted from the cask from the high level radioactive waste.

### Claim 2 (depends on 1)

The system according to claim 1, wherein the cooling jacket comprises a metallic inner shell and a metallic outer shell, the cooling medium cavity being defined between the inner and outer shells.

### Claim 3 (depends on 2)

The system according to claim 2, wherein the cooling jacket further comprises an annular top closure plate affixed to top ends of the inner and outer shells, and an annular bottom closure plate affixed to bottom ends of the inner and outer shells.

### Claim 4 (depends on 1)

The system according to claim 1, wherein the cooling jacket has a height which extends for at least a majority of a height of the cask.

### Claim 5 (depends on 2)

The system according to claim 2, wherein the inner shell is formed of a material having a greater heat transfer coefficient than the outer shell.

### Claim 6 (depends on 5)

The system according to claim 5, wherein the inner shell is formed of copper and the outer shell is formed of a different material.

### Claim 7 (depends on 1)

The system according to claim 1, further comprising a plurality of circumferentially spaced apart stiffening plates arranged in the cooling medium cavity of the cooling jacket and extending longitudinally and in a radial direction between the inner and outer shells, the stiffening plates extending for a majority of a height of the inner and outer shells to divide the cooling medium cavity into a plurality of cooling compartments each configured for holding the cooling medium.

### Claim 8 (depends on 3)

The system according to claim 3, wherein the top closure plate includes an openable and closeable access hatch configured for filling the cooling medium cavity of the cooling jacket with the cooling medium.

### Claim 9 (depends on 1)

The system according to claim 1, wherein the cooling medium is a solid substance having a triple point at a pressure which is greater than normal atmospheric pressure such that the cooling medium sublimates at normal atmospheric pressure inside the cooling jacket.

### Claim 10 (depends on 9)

The system according to claim 9, wherein the cooling medium is dry ice.

### Claim 11 (depends on 10)

The system according to claim 10, wherein the dry ice is in pellet or block form.

### Claim 12 (depends on 3)

The system according to claim 3, wherein the cooling medium is dry ice and the top closure plate further includes a plurality of vents in fluid communication with the internal cavity of the cooling jacket, the vents circumferentially spaced apart and configured for venting gaseous carbon dioxide to atmosphere from the cooling medium cavity which is created by sublimation of the dry ice upon absorbing the heat emitted by the cask from the high level radioactive waste.

### Claim 13 (depends on 1)

The system according to claim 1, wherein the cooling jacket is removably mounted to the cask.

### Claim 14 (depends on 13)

The system according to claim 13, wherein the cooling jacket further comprises a plurality of hangers extending upwards from a top end of the cooling jacket and having a hook shape configured to hang the cooling jacket from a top surface of the cask in a suspended manner.

### Claim 15 (depends on 14)

The cooling system according to claim 14, wherein the hangers comprise L-shaped brackets including a vertical section fixedly attached to the top end of the cooling jacket and a horizontal section extending inwards beyond an innermost surface of the cooling jacket to engage a peripheral top mounting flange of the cask.

### Claim 16 (depends on 1)

The system according to claim 1, further comprising a circumferentially-extending insulation jacket disposed on an external surface of the cooling jacket.

### Claim 17 (depends on 1)

The system according to claim 1, wherein the cooling jacket further comprises a plurality of circumferentially spaced apart spacers arranged on an internal surface of the cooling jacket, the spacers maintaining an empty annular interstitial space between the cooling jacket and the cask to allow some of the heat emitted from the cask to be removed by cooling air flow.

### Claim 18 (depends on 17)

The system according to claim 17, wherein the spacers comprising a first circular array of block-shaped spacers arranged on an upper half of the internal surface of the cooling jacket, and a separate second circular array of block-shaped spacers arranged on a lower half of the internal surface of the cooling jacket.

### Claim 19 (depends on 2)

The system according to claim 2, wherein the cooling jacket comprises a first semi-circular segment having ends abutted to end of a second semi-circular segment to form a continuous annular structure.

### Claim 20 (depends on 19)

The cooling system according to claim 19, wherein each of the first and second semi-circular segments comprises a pair of vertical end plates extending between the inner and outer shells arranged at opposing sides of each segment, the end plates the first semi-circular segment abutting the end plates of the second semi-circular segment at a flat-to-flat interface.

### Claim 21 (depends on 1)

The system according to claim 1, further comprising a canister loaded with the high level radioactive waste, the canister positioned within the storage cavity of the cask.