High Quality Content by WIKIPEDIA articles! Operation Grapple, and operations Grapple X, Grapple Y and Grapple Z, were the names of British nuclear tests of the hydrogen bomb. They were held 1956—1958 at Malden Island and Christmas Island in the central Pacific Ocean. Nine nuclear detonations took place during the trials, resulting in Britain becoming a thermonuclear power. All of the bombs were exploded in the air, rather than on the surface, to reduce the effects of fallout.