US3886368A — Spent fuel shipping cask

Claim 1

Independent Claim 136 words

A shipping cask for spent nuclear fuel assemblies, comprising: means defining a generally cylindrical enclosure having a closed end and an open end; gamma ray shielding material surrounding said enclosure; neutron shielding means extending circumferentially around said gamma ray shielding material comprising means defining a plurality of separate longitudinally extending compartments for bodies of liquid material capable of absorbing neutrons; pressure relief means for each of said compartments; and each of said compartments comprising a main portion and a surge tank portion separated therefrom by a partition, a small passageway through said partition, and means at said passageway for holding a body of said liquid in closing relation to said passageway throughout a substantial range of tilting of said cask to thereby prevent air from flowing from said surge tank portion into said main tank portion.

Claim 2

Dependent Claim 136 words

A shipping cask for spent nuclear fuel assemblies, comprising: means defining a generally cylindrical enclosure having a closed end and an open end; gamma ray shielding material surrounding said enclosure; neutron shielding means extending circumferentially around said gamma ray shielding material comprising means defining a plurality of separate longitudinally extending compartments for bodies of liquid material capable of absorbing neutrons; pressure relief means for each of said compartments; and each of said compartments comprising a main portion and a surge tank portion separated therefrom by a partition, a small passageway through said partition, and means at said passageway for holding a body of said liquid in closing relation to said passageway throughout a substantial range of tilting of said cask to thereby prevent air from flowing from said surge tank portion into said main tank portion.

Claim 3

Dependent Claim 112 words

A shipping cask as defined in claim 1 and including: a first pair of radially outwardly extending diametrically opposed and axially aligned trunnions adjacent said open top; and a second pair of opposed and axially aligned trunnions extending outwardly from adjacent said closed bottom and from opposite sides of said cask with their aligned axes parallel to the axes of the trunnions of said first pair, the trunnions of said second pair being laterally offset from the longitudinal axis of said cask whereby when said second pair of trunnions is engaged with a supporting cradle, with said cask upright, said cask will be unbalanced and tend to tilt toward a horizontal position.

Claim 4

Dependent Claim 28 words

A cask as defined in claim 1 wherein each of said compartments is provided with a solder filled opening in its outer wall, serving as a blow-out plug.

Claim 5

Dependent Claim 20 words

A cask as defined in claim 1 wherein said bodies of liquid material comprise potassium tetraborate, water and ethylene glycol.

Claim 6

Dependent Claim 31 words

A cask as defined in claim 4 wherein said ethylene glycol comprises about 70% of said body of liquid material and about 0.6% of said body of liquid material is boron.

Claim 7

Dependent Claim 181 words

A cask as defined in claim 1 wherein said compartments extend axially of said cask less than the full length of said enclosure, having their ends inwardly of the ends of said enclosure. 7. A shipping cask for spent nuclear fuel assemblies, comprising: means defining a generally cylindrical enclosure having a closed end and an open end; gamma ray shielding material surrounding said enclosure; neutron shielding means extending circumferentially around said gamma ray shielding material comprising means defining a plurality of separate longitudinally extending compartments for bodies of liquid material capable of absorbing neutrons; pressure relief means for each of said compartments; said gamma ray shielding comprising radially spaced generally concentric tubes of stainless steel; an annular body of lead substantially but not completely filling the space between said tubes; a body of stainless steel defining said closed end and being wElded to the adjacent ends of said tubes; an annular flange of stainless steel welded to the other ends of said tubes and defining said open end; and a stainless steel closure secured to said flange and being sealed thereto.

Claim 8

Dependent Claim 40 words

A cask as defined in claim 7 wherein said closure is sealed to said flange by a pair of spaced O-ring gaskets, and a gasket leak check valve carried by said flange and communicating with the space between said O-rings.

Claim 9

Dependent Claim 30 words

A cask as defined in claim 7 including metal vanes secured to at least one of said tubes and extending into said body of lead to enhance heat transfer therebetween.

Claim 10

Dependent Claim 101 words

A shipping cask for spent nuclear fuel assemblies, comprising: means defining a generally cylindrical enclosure having an open top and closed bottom and comprising thick metal members, of gamma ray shielding material, defining said closed bottom and said open top; a radial cavity extending inwardly from the outer surface of said cask into at least one of said members; a passageway extending inwardly from said cavity to a space within said cask; and valve means for closing said passageway, said valve means being entirely within said cavity within said gamma ray shielding material and thereby protected from damage by external impacts.

Claim 11

Dependent Claim 101 words

A shipping cask for spent nuclear fuel assemblies, comprising: means defining a generally cylindrical enclosure having an open top and closed bottom and comprising thick metal members, of gamma ray shielding material, defining said closed bottom and said open top; a radial cavity extending inwardly from the outer surface of said cask into at least one of said members; a passageway extending inwardly from said cavity to a space within said cask; and valve means for closing said passageway, said valve means being entirely within said cavity within said gamma ray shielding material and thereby protected from damage by external impacts.

Claim 12

Dependent Claim 26 words

A cask as defined in claim 10 wherein said valve comprises a rupture disc device adjacent said passageway and a pressure relief valve in series therewith.

Claim 13

Dependent Claim 65 words

A cask as defined in claim 10 including an annular structure around said one member; an opening through said structure and communicating with said cavity; said valve having an outlet port and a frangible tube extending outwardly from said outlet port into said opening; and a normally closed, selectively openable valve at the outer end of said tube adjacent the outer end of said opening.

Claim 14

Dependent Claim 29 words

A cask as defined in claim 12 including a removable closure sealingly closing the outer end of said opening and including thermal insulation protecting said valve from external fire.

Claim 15

Dependent Claim 122 words

A shipping cask for spent nuclear fuel assemblies, comprising: means defining a generally cylindrical cask having an open top and a closed bottom; a closure sealingly closing said open top; a selected portion of the outer surface of said cask having a body of balsa wood overlying the same to protect said cask against external impacts, said balsa wood being arranged with its grain extending generally perpendicular to said surface, said balsa wood being enclosed in a metal shell secured to said cask over said surface; generally radially extending reinforcing plates extending through said metal shell and said balsa wood and being secured to said cask; and a layer of asbestos between the outer surface of said balsa wood and said shell.

Claim 16

Dependent Claim 122 words

A shipping cask for spent nuclear fuel assemblies, comprising: means defining a generally cylindrical cask having an open top and a closed bottom; a closure sealingly closing said open top; a selected portion of the outer surface of said cask having a body of balsa wood overlying the same to protect said cask against external impacts, said balsa wood being arranged with its grain extending generally perpendicular to said surface, said balsa wood being enclosed in a metal shell secured to said cask over said surface; generally radially extending reinforcing plates extending through said metal shell and said balsa wood and being secured to said cask; and a layer of asbestos between the outer surface of said balsa wood and said shell.

Claim 17

Dependent Claim 41 words

A shipping cask as defined in claim 14 wherein said surface is the bottom of said cask, said sheel extending outwardly of the periphery of said cask and serving as a broad base for supporting said cask in an upright position.

Claim 18

Dependent Claim 33 words

A shipping cask as defined in claim 14 wherein said shell overlies said closure and open end of said cask and is removably secured to said closure and sealed to said open end.

Claim 19

Dependent Claim 122 words

A shipping cask for spent nuclear fuel assemblies, comprising: means defining a generally cylindrical hollow enclosure having a closed end and an open end; removable elongated generally flat plates of gamma ray shielding material arranged to extend chordally and loosely positioned in said enclosure and defining at least one generally square compartment therebetween for a fuel assembly; and defining spaces between said plates and the inner periphery of said enclosure, for coolant flow; means providing for flow of coolant in said enclosure into said out of said compartment; adjacent edges of said plates being spaced apart and opposite ends of said plates being secured to end members common to said plates whereby said compartment is the interior of a Unitary removable container.

Claim 20

Dependent Claim 122 words

A shipping cask for spent nuclear fuel assemblies, comprising: means defining a generally cylindrical hollow enclosure having a closed end and an open end; removable elongated generally flat plates of gamma ray shielding material arranged to extend chordally and loosely positioned in said enclosure and defining at least one generally square compartment therebetween for a fuel assembly; and defining spaces between said plates and the inner periphery of said enclosure, for coolant flow; means providing for flow of coolant in said enclosure into said out of said compartment; adjacent edges of said plates being spaced apart and opposite ends of said plates being secured to end members common to said plates whereby said compartment is the interior of a Unitary removable container.

Claim 21

Dependent Claim 36 words

A cask as defined in claim 17 including foraminous material extending across the spaces between said plates whereby to retain fuel particles from any ruptured fuel rods in said compartment while permitting circulation of coolant therethrough.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1978-05-26	1978-11-25	1979-05-27	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1982-05-26	1982-11-25	1983-05-27	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1986-05-26	1986-11-25	1987-05-27	$7700.00	Window Closed / Lapsed

Spent fuel shipping cask

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