Operation Grapple

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Operation Grapple, and operations Grapple X, Grapple Y and Grapple Z, were series of British nuclear testing operations which sought to test a hydrogen bomb. The operations were conducted from 1956 to 1958 at Malden Island and Christmas Island (now Kiritimati). A total of 9 nuclear detonations took place during the trials and resulted in Britain becoming a thermonuclear power.

Untested and unproven thermonuclear designs being developed at Britain's nuclear weapons research establishment, the AWRE, required proof testing. For this reason, Grapple was conducted as a massive tri-service operation, the largest of its kind since World War II. Initial work and preparation of the operation, as well as establishment of the necessary infrastructure on Christmas Island, began in the end of May 1956. About 1,200 civilian and military personnel were stationed on Christmas Island during this year. All of the bombs were exploded in the air, rather than on the surface, to reduce the effects of fallout.

Initial landings were from the Bibby Line troopship Devonshire which had sailed from the Far East and embarked servicemen at Suva (Fiji) who had been flown from the United Kingdom by commercial airlines. From early October, following the rebuilding of the island's main runway, the majority of arrivals came directly from the United Kingdom, via Hawaii, using Qantas chartered Super Constellation aircraft. Departures of the first arrivals started early June 1957, using the same Qantas arrangement to Hawaii.

While Christmas was the main base, three other locations featured as key elements of the operation. Malden Island, about 200 miles south of Christmas Island was the site for the air-dropped tests, and Penrhyn Island, a further 200 miles south was used as a monitoring site and weather station. Air support for the operation was generally routed through Hickam Air Base on the Hawaiian Islands to the north, where a support group was located.

Supplies for the island were shipped primarily from the southern hemisphere — Australia and New Zealand, by freighters of the Royal Fleet Auxiliary (RFA). The Royal Navy established a water processing plant early in the operation, which provided adequate supplies of drinking water and semi-salt water for showering.

1 Grapple
2 Grapple X
3 Grapple Y
4 Grapple Z
5 Cooperation with the USA
6 See also
7 References
8 External links
9 Notes

[edit] Grapple

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 1 megaton. The bomb was dropped by a Vickers Valiant XD818 [1], piloted by Kenneth Hubbard, over Malden Island on May 15, 1957. The bomb weighed around 4,545 kg.

The bomb exploded with a force of 300 kilotons. This yield was far below the predicted power of the bomb. Despite this, Britain hailed this test as a successful thermonuclear explosion and announced to the world it had become a thermonuclear power. While disappointing, the AWRE scientists learned valuable information regarding radiation implosion.

The next test was Orange Herald (small). This was a large fission bomb which was hoped to arm a future ballistic missile. The bomb was dropped and detonated by a Valiant on May 31, 1957. It exploded with a force of 720 kilotons. The yield was the largest ever achieved by similar bomb designs. This bomb was hailed by the government as a new type hydrogen bomb and that fact it was a fission bomb was kept secret by the government till the end of the Cold War.

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 was a fourth design that was not tested: 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.

[edit] Grapple X

Following the disappointing results of the first Grapple trial, Grapple X was conducted at Christmas Island. For Grapple X, the bombs would be exploded over Christmas Island instead of Malden Island to save time and money.

With the experience and knowledge gained from the first Grapple trial, the scientists had developed a new hydrogen bomb design with a 50% more powerful fission trigger 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 force of 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 collateral damage to the island, resulting in demolished buildings and damaged infrastructure. This damage was due to the high yield of the test, which was not expected.

Grapple X was spectacularly successful, exceeding the predicted yield of 1 megaton almost by 100%. Britain became a true thermonuclear power with the detonation of Grapple X.

[edit] 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. The bomb achieved a yield of three megatons and was the largest British nuclear test ever conducted. ^[1] The Grapple Y design was successful as the majority of the yield came from thermonuclear reactions instead of fast fission yield from the uranium tamper.

[edit] Grapple Z

With a nuclear testing moratorium quickly approaching, Grapple Z was conducted at Christmas Island in the summer of 1958. This was a four shot series and the largest of the four Grapple trials. Grapple Z sought to develop smaller nuclear warheads as well as radiologically hardened weapons.

The first shot, codenamed Pendant, was detonated on August 22, 1958. Rather than being dropped by a bomber, the bomb was suspended from balloons. Pendant had a 24 kiloton yield and explored the use of an external neutron initiator. ^[1]

The next shot, Flagpole, was airdropped over Christmas Island on September 2, 1958. It exploded with a yield of 1.2 megatons. This test was followed by Halliard 1 (September 11, 1958) and Burgee (September 23, 1958 ). These last two tests had yields of 800 kilotons and 25 kilotons respectively. Grapple Z was the last atmospheric nuclear testing trial conducted by Britain. ^[1]

By the end of Grapple Z, Britain had the capability of making a 1 megaton H-bomb that weighed no more than 1 ton and was immune to radiation from nearby nuclear weapons.

[edit] Cooperation with the USA

The practical result of the British H-bomb project was that the United States became willing to enter into the 1958 US-UK Mutual Defence Agreement. This put an end to Britain's independent nuclear weapons system in favour of American designs. The Americans, to their surprise, also benefited by access to information where Britain was technically ahead including details of explosives and electronics, and experience in designing weapons without large numbers of tests. While the designs tested during Grapple were successful, they were not put into service by Great Britain.