A canister arranged for storing spent nuclear fuel, comprising: a first end portion; a second end portion, wherein the second end portion comprises a connector portion arranged for facilitaing coupling of the canister to a downhole tool to permit deposit and retrieval of the canister to and from storage in a drillhole; and a middle portion comprised of a first material of a composition and thickness that allow transmission of gamma rays therethrough and out of the canister, wherein i) the middle portion is attached to the first and second end portions such that the middle portion, first end portion, and second end portion collectively enclose an interior volume (105, 175) of the canister that is sized to store at least one spent nuclear fuel assembly, wherein the interior volume has a height dimension and a cross-sectional diameter sized to enclose the at least one spent nuclear fuel assembly, and ii) the first and second end portions comprise shielding of a second material of a composition and thickness that reduce an intensity of gamma ray radiation to a level that allows safe handling of the canister, wherein the second material comprises lead with a thickness between 5cm (2 inches) and 10cm (4 inches) or concrete with a thickness between 91cm (3 feet) and 152cm (5 feet). a first end portion; a second end portion, wherein the second end portion comprises a connector portion arranged for facilitaing coupling of the canister to a downhole tool to permit deposit and retrieval of the canister to and from storage in a drillhole; and a middle portion comprised of a first material of a composition and thickness that allow transmission of gamma rays therethrough and out of the canister, wherein i) the middle portion is attached to the first and second end portions such that the middle portion, first end portion, and second end portion collectively enclose an interior volume (105, 175) of the canister that is sized to store at least one spent nuclear fuel assembly, wherein the interior volume has a height dimension and a cross-sectional diameter sized to enclose the at least one spent nuclear fuel assembly, and ii) the first and second end portions comprise shielding of a second material of a composition and thickness that reduce an intensity of gamma ray radiation to a level that allows safe handling of the canister, wherein the second material comprises lead with a thickness between 5cm (2 inches) and 10cm (4 inches) or concrete with a thickness between 91cm (3 feet) and 152cm (5 feet). i) the middle portion is attached to the first and second end portions such that the middle portion, first end portion, and second end portion collectively enclose an interior volume (105, 175) of the canister that is sized to store at least one spent nuclear fuel assembly, wherein the interior volume has a height dimension and a cross-sectional diameter sized to enclose the at least one spent nuclear fuel assembly, and ii) the first and second end portions comprise shielding of a second material of a composition and thickness that reduce an intensity of gamma ray radiation to a level that allows safe handling of the canister, wherein the second material comprises lead with a thickness between 5cm (2 inches) and 10cm (4 inches) or concrete with a thickness between 91cm (3 feet) and 152cm (5 feet).