Operation Grapple

Operation Grapple, and operations Grapple X, Grapple Y and Grapple Z, were the names of British nuclear weapons tests of very-early hydrogen bombs. These tests were carried out from 1956 until 1958 at Malden Island and Christmas Island in the Central Pacific Ocean. Nine nuclear explosions were executed during these series of nuclear weapon tests, culminating in the United Kingdom's becoming the third recognized possessor of thermonuclear weapons.

All of these nuclear bombs were exploded high in the atmosphere, rather than being detonated on the ground, in order to reduce the production of nuclear fallout.

The unproven H-bomb designs being developed by British weaponeers required full-scale testing of their capabilities, hence Operation Grapple was carried out as a massive military operation in the Central Pacific, and this the largest British military operation carried out since World War II. The preparations for Operation Grapple, including building the necessary structures on Christmas Island, began at the end of May 1956. About 1,200 civilians and servicemen were sent to Christmas Island during 1956. The first deliveries to Christmas Island were made by the troopship Devonshire, which steamed to the Central Pacific from East Asia and took construction troops aboard at Fiji. These men had flown there from the U.K. on commercial airliners. The first project on Christmas Island, which was finished in October, was to rebuild the main runway at the airport. The majority of troops and civilians were then flown in from the U.K., via Canada and Hawaii, in chartered airliners. The original troops began to be flown out in mid-1957.

While Christmas Island was the main base, three other islands supported Operation Grapple. The area around Malden Island, located about 330 kilometers south of Christmas Island, was to be the site for the bomber-dropped tests, and Penrhyn Island, 320 kilometers farther south was used as a technical monitoring site and as a weather station. Air deliveries of cargo for Operation Grapple were generally sent via Hickam Air Force Base (of the U.S. Air Force) in the American Territory of Hawaii, where a transport group of the Royal Air Force was assigned.

Seaborne supplies for Operation Grapple were usually shipped via Australia or New Zealand, using freighters of the Royal Fleet Auxiliary (RFA). The British Royal Navy built a seawater processing plant on Christmas Island early during Operation Grapple, and this which provided freshwater for drinking and cooking, and semisaline water for bathing.

Explosions
The first trial was Grapple, also known as Grapple 1. All of these nuclear bombs were dropped and detonated over Malden Island. The first test of this trial was code-named Short Granite. It was a two-staged nuclear weapon that had a predicted yield of about one megaton. This bomb was dropped by a Vickers Valiant bomber XD818, piloted by Kenneth Hubbard, off the shore of Malden Island on 15 May 1957.

Weighing about 4,550 kilograms, this bomb exploded with a power of about 300 kilotons, a yield far below its designed capability. Despite this problem, the British government hailed this test as a successful thermonuclear explosion, and the government announced to the world that the U.K. had become a thermonuclear power. While the results of this test were disappointing, the British learned much about radiation implosion in H-bombs.

The next test was Orange Herald. This was a large fission bomb which was hoped to arm a future ballistic missile. The bomb was dropped and detonated by a Valiant bomber on May 31, 1957. It exploded with a force of about 720 kilotons. The yield was the largest ever achieved by similar bomb designs. This bomb was hailed by the government as a new type of hydrogen bomb and the fact that it was a fission bomb was kept secret by the government until the end of the Cold War. A 400 kiloton very-large atomic bomb code-named "Green Grass" was derived from Orange Herald, and it was deployed during the period before an actual H-bomb became available. The last shot of Grapple was Purple Granite. This was a last minute addition to the operation and was hoped to give an improved yield over Short Granite. The bomb was detonated on June 19, 1957, with a 200 kiloton yield.

There were other designs that were not tested: Green Bamboo was a single stage thermonuclear bomb similar to the Soviet Joe-4, and Orange Herald (large) was a "political bomb": a large fission bomb that was not suitable for use as a weapon but was certain to give a high yield ensuring that Britain would not appear as a failed nuclear power.

The two Granites and Green Bamboo were designed to achieve high yields by using the Li-6 D/U-238 cycle rather than the large-scale fusion of deuterium achieved at Grapple-Y.

Grapple X
Following the disappointing results of the first Grapple trial, Grapple X was conducted at Christmas Island. For Grapple X, the bombs were exploded over Christmas Island instead of over Malden Island to save time and money. With the experience and knowledge gained from the first Grapple tests, the weaponeers had developed a new H-bomb design with a 50 percent more powerful fission primary stage and a simplified thermonuclear secondary. Grapple X was dropped and detonated over the southern end of Christmas Island on November 8, 1957. The two-stage thermonuclear bomb exploded with a yield of about 1.8 megatons. This was close to being the real hydrogen bomb Britain wanted, but used a relatively large quantity of (expensive) highly enriched uranium.

The explosion did some damage to the island, resulting in some demolished and damaged military buildings. This damage was due to the higher-than-expected yield of the explosion.

Grapple X was spectacularly successful, exceeding its predicted yield of one megaton by about 80 percent. The U.K. had become an actual thermonuclear power with the detonation of Grapple X.

Grapple Y
Grapple Y sought to develop a more efficient thermonuclear bomb based on the successful Grapple X design. Like Grapple X, only one detonation was conducted during Grapple Y. The bomb was detonated off Christmas Island on April 28, 1958. This bomb had an explosive yield of about 3.0 megatons, and it was the largest British nuclear weapons test ever executed anywhere.

The design of Grapple Y was notably successful because much of its yield came from its thermonuclear reaction instead of from the fast fission of a heavy uranium-238 tamper - hence making it a true H-bomb, and also because its yield had been closely predicted—indicating that its designers understood what they were doing.

Grapple Z
With a nuclear testing moratorium quickly approaching, Operation Grapple Z was carried out at Christmas Island during mid-1958. This was a four-bomb test series, and the largest of the four in the Grapple series. Grapple Z sought to develop lighter nuclear warheads as well as weapons that were radiologically hardened - meaning they would not be destroyed prematurely if exposed to nuclear radiation from other nuclear explosions. Two of the Grapple Z tests were fission bombs tested for development of the primary stage of a two-stage hydrogen bomb. The first shot, with the code name of Pendant, was detonated on August 22, 1958. Rather than being dropped from a bomber, this bomb was suspended from a string of four vertically stacked barrage balloons. The Pendant test had a yield of about 24 kilotons, and it used solid hydrogen fusion boosting using lithium deuteride. The next shot, called Flagpole, was dropped by a bomber flying over Christmas Island on September 2, 1958. This bomb was a smaller version of the one exploded in Grapple Y, and it detonated with a yield of about 1.2 megatons. This test was followed by one called Halliard 1, on September 11, 1958, which was an unusual three-stage bomb with two nuclear-fission components followed by one thermonuclear stage. This bomb had its predicted yield of 800 kilotons, and it was supposedly immune to exposure from another bomb despite its not using boosting. The final test was called Burgee, on September 23, 1958, which another balloon-borne test which was an atomic bomb boosted with gaseous tritium. It had a yield of about 25 kilotons.

The last bomb in the Grapple Z series was the very last nuclear explosion carried out in the atmosphere by the U.K. The result of it was that the weapon makers of the U.K. had demonstrated all of the technologies that were needed to produce a one-megaton hydrogen bomb that weighed no more than one ton (2,200 pounds), and it was also immune to premature detonation caused by nearby nuclear explosions.

Cooperation with the USA
The practical result of the British H-bomb project (in conjunction with other political events ) was that the United States became willing to enter into the 1958 US-UK Mutual Defence Agreement. This put an end to independent nuclear weapons development by the U.K. in favor of a program that was closely based on the American designs. The benefit to the U.K. was that this was much cheaper than developing its own designs for weapons that could be made in large numbers, and then deployed. An additional benefit was that the U.K. was able to buy highly enriched uranium from the U.S. and also sell plutonium to it made in British nuclear reactors. This was a deal that was useful to both parties and also profitable for the U.K. To their surprise, American nuclear weapons designers also benefited from access to information from the U.K. about the details of its high explosives and weapons electronics, and from the experience of designing nuclear weapons without large numbers of nuclear weapons test explosions.

While the thermonuclear bomb designs tested by the U.K. during Operation Grapple were successful, they were never manufactured. The useful effect of the British tests was to increase the quality of information that the American Atomic Energy Commission was willing to share with the U.K., and also for British weapons designers to learn how to use that information successfully.

Health effects
In 2005, a Massey University study in New Zealand concluded that sailors from the Royal New Zealand Navy, Royal Navy and Fijian Navy who observed the tests from nearby ships later suffered adverse health effects from exposure to radiation fallout, including cancer and genetic abnormalities in the veterans' children. A class action lawsuit was filed against the British Ministry of Defence by various veterans' organisations following the publication of the study.

The Ministry of Defence maintains that few people were exposed to any radiation or contamination at all, and that studies had shown little or no health effects. An analysis of illnesses in veterans of Grapple and other weapons tests produced statistics that are hard to interpret. The veterans showed rates of illness that were slightly higher than the control group, but the control group had lower rates of illness than the population as a whole while the veterans had rates that were about the same. Neither of these results has a clear explanation. Reliable statistical analysis of the data is difficult because the samples are fairly small and incomplete.

In March 2012, a group of 1,011 British ex-servicemen were denied permission to sue the UK Ministry of Defence by the Supreme Court, on the grounds that too much time had elapsed since they became aware of their medical conditions, under the terms of the Limitation Act 1980.