By Courtney Sherwood PORTLAND, Ore. (Reuters) – A group of Oregon children who stumbled across an un-detonated, decades-old military-grade mortar shell in a Portland wildlife refuge took it to a play date but escaped unharmed, Portland police said on Wednesday. The foot-long (30-cm-long) weapon was likely tossed as refuse into the Oaks Bottom Wildlife Refuge, and officials do not expect to find any more un-detonated bombs in the area, said Portland Police Bureau spokesman Pete Simpson. The children who found the dull-green, stout torpedo-shaped explosive carried it about one mile to a local home, at which point an adult called police.