page_title: British nuclear testing in the United States
section_title: Testing
hierarchical_section_title: British nuclear testing in the United States / Testing
caption_attribution_description: English: Preparing for an underground test at the Nevada Test Site. Original caption: Final test preparations include running miles of cable downhole which will transmit vital test information to the diagnostic trailers to the left. A rack containing instrumentation to go downhole is assembled in the tower to the right. Subsidence craters from earlier underground tests dot the landscape.
context_page_description: Following the success of Operation Grapple in which the UK joined the club of thermonuclear nations, Britain launched negotiations with the US on a treaty under in which both could share information and material to design, test and maintain their nuclear weapons. This effort culminated in the 1958 US–UK Mutual Defence Agreement. One of the results of that treaty was that Britain was allowed to use United States' Nevada Test Site for testing their designs and ideas, and received full support from the personnel there, in exchange for the data "take" from the experiment, a mutual condition. In effect the Nevada Test Site became Britain's test ground, subject only to advance planning and integrating their testing into that of the United States. This resulted in 24 underground tests at the Nevada Test Site from 1958 through the end of nuclear testing in the US in September 1992.
  The United Kingdom signed the Comprehensive Nuclear Test Ban Treaty in 1996 and ratified it in 1998, confirming the British commitment towards ending nuclear test explosions in the world.
context_section_description: The MDA did not specifically address British nuclear testing at the Nevada Test Site (NTS), but it did provide a high-level framework for it to occur. The prospect was raised by the British Ambassador to the United States, Sir Roger Makins, at a meeting with the Chairman of the AEC, Glenn T. Seaborg, and Sir William Penney, the head of nuclear weapons development at the United Kingdom Atomic Energy Authority (UKAEA). On 3 November 1961, Macmillan wrote to President John F. Kennedy requesting the use of the Nevada Test Site for the testing of Super Octopus, a British kiloton warhead intended for use with the American Skybolt missile that was of great interest to weapon designers on both sides of the Atlantic. The response was positive, and on 8 February 1962, Seaborg announced, specifically referencing the MDA, that there would be a UK nuclear test at the NTS. This developed into a procedure for approval of a British nuclear test. The director of the British Atomic Weapons Research Establishment (AWRE) would lodge a request with the chairman of the AEC, who would then make a recommendation to the president through the Secretary of State and the Secretary of Defence. Every test had to be approved by the president and the National Security Council.
  A Joint Working Group (JOWOG) was set up to coordinate the British tests. Test safety and containment requirements remained a US Federal responsibility. The JOWOG therefore decided that the UK would provide the test device and diagnostics package, while the US would provide everything else, including the test canister and the data cables leading from it to the trailers with US recording equipment. This threw up issues regarding the interface between the British diagnostics package and the American recording equipment. There were also issues related to procedures, particularly with regard to the testing of electronic and mechanical devices. A further complicating factor was that the US had two rival nuclear weapons laboratories, the Los Alamos National Laboratory (LANL) and the Lawrence Livermore National Laboratory (LLNL), with different procedures.
  For the first test, E. R. Drake Seager from the AWRE was designated the trial superintendent and Robert Campbell from LANL was designated the test director, these being the styles of the heads of the British and American teams. The test, codenamed Pampas, was conducted on 1 March 1962. It was Britain's first underground test. The new Super Octopus implosion system worked but the overall result was disappointing. The RO.106 (Tony) warhead was based on the American Tsetse warhead, but used a different, safer but less powerful conventional explosive, EDC11. The result was that the yield was less than Tsetse, and too small to be used as the primary in the Skybolt warhead. A follow-up test of what became the basis for the WE.177 design codenamed Tendrac therefore took place on 7 December 1962, and was judged a success.
  Subcritical tests were tests with nuclear weapons that did not involve a nuclear explosion. Safety tests involved testing the impact of fire, shock and other accidents against live nuclear weapons. These did not intentionally involve nuclear explosions, although there was always a danger. Tim subcritical tests and Vixen safety tests related to WE.177 were conducted at Maralinga in March and April 1963, but four more British safety tests were conducted in 1963 at the NTS Tonopah Test Range as part of Operation Roller Coaster: Double Tracks on 15 May, Clean Slate 1 on 25 May, Clean Slate 2 on 31 May and Clean Slate 3 on 9 June. The Partial Nuclear Test Ban Treaty, which went into effect on 10 October 1963, banned atmospheric nuclear testing, and the Maralinga range was closed for good in 1967.
  The Polaris Sales Agreement, which was signed in Washington, DC, on 6 April 1963, meant that a new warhead was required. The Skybolt warhead tested in Tendrac had to be redesigned with a Re-Entry System (RES) that could be fitted to a Polaris missile, at an estimated cost of between £30 million and £40 million. The alternative was to mak
caption: Preparing for an underground test at the Nevada Test Site. Final test preparations include running miles of cable downhole which will transmit vital test information to the diagnostic trailers to the left. A rack containing instrumentation to go downhole is assembled in the tower to the right. Subsidence craters from earlier underground tests dot the landscape.
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