Britain’s Biggest Explosion — Grapple Y

  • Lorna Arnold
  • Katherine Pyne


Grapple X had exceeded expectations. It had been a big bang, at 1.8 megatons. But was it a real hydrogen bomb or, as K. W. Allen suggested, more like a double boosted bomb? Did that matter? Did it fulfil the remit given to Aldermaston in July 1954 and was it the superbomb the Chiefs of Staff wanted? Cook simply concluded that it showed a measure of agreement between theoretical predictions and observed results which indicated that Aldermaston was beginning to understand the processes involved. This, after all, was a prime purpose of nuclear weapon tests (see Preface).


Blast Wave Natural Uranium Nuclear Weapon Test Thermonuclear Reaction Danger Area 
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Notes and References

  1. 1.
    Conversation with K. W. Allen at Aldermaston, 12 July 1995.Google Scholar
  2. 2.
    See ch. 6. The same epidemic affected Windscale at the time of the reactor fire in early October 1957.Google Scholar
  3. 3.
    The actual height of burst (in metres) for Grapple Y compares with other Grapple shots as follows: Short Granite 2200, Orange Herald 2400, Purple Granite 2400, Grapple X 2200, Grapple Y 2500, Flagpole 2800, Halliard 2600.Google Scholar
  4. 4.
    By contrast, a participant in the American Ivy trials in 1952 (quoted by R. Rhodes, Dark Sun, p. 503) wrote ‘The nice thing about being overseas is that they feed you very well. They understand that if you want to have happy guys, you ration the booze … but you serve very good food; shrimp, steak, … lots of ice cream.’Google Scholar
  5. 5.
    By agreement with the United States and New Zealand governments.Google Scholar
  6. 6.
    K. Hubbard and M. Simmons, Operation Grapple, p. 114.Google Scholar

Copyright information

© The Ministry of Defence 2001

Authors and Affiliations

  • Lorna Arnold
  • Katherine Pyne

There are no affiliations available

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