A parachute-retarded LRL device in a MK-36 drop case. This was a test of advanced principles for achieving high-efficiency thermonuclear burn, and successfully confirmed theoretical predictions. It was said to “show the way to a new range of possibilities in high-yield design”. This was the last Christmas Island airdrop, and the third largest test of Operation Dominic. Yield-to-weight ratio was 0.934 kt/kg (but then this was an experiment, not a final weapon configuration).
The importance of this test is underscored in a letter from U.S. Deputy Special Assistant for National Security Affairs Carl Kaysen to Sir David Ormsby Gore, ambassador of Great Britain:
The President has authorized the firing of the Ripple device as the Pamlico Event. . . . This test, if successful, will permit the achievement of much greater [End Page 145] yield-to-weight ratios in weapons. While technically it embodies a different concept than the [deleted—unknown?] it is designed to achieve the same result. It can be viewed as a substitute for it. In terms of the group of categories that we gave you on 27 February, this falls in the first class of advanced concepts.37
On 11 July, the 9,162-pound Ripple device was air-dropped from a B-52 and detonated at an altitude of 14,330 feet, yielding 3.85 megatons. The “physics package” was a cylinder 123.4 inches long and 56.2 inches wide. The predicted yield was 3 to 5 megatons. Nuckolls witnessed the test in person and described the event and the reaction of his Livermore colleagues:
On a pre-dawn morning in early July 1962, I observed the multi-megaton yield “Pamlico” explosion of my device from a Christmas Island beach at the Joint Task Force Eight Pacific nuclear test site. We wrapped in white sheets to avoid thermal radiation and wore dark goggles. Fifty miles distant, a B52 had dropped the parachute retarded nuclear device. Suddenly, we were stunned and dazzled by the multi-megaton pulse of intense light and heat radiated from the three-kilometer fireball. Night became day. The giant mushroom cloud surged upward and stabilized at an altitude of 80,000 feet. The Soviet spy ship was steaming over the horizon.
Foster sent the director’s car to meet me at the San Francisco airport. Later, he hosted a dinner/musical celebration at San Francisco’s Palace Hotel.
My colleagues were amazed at my beginner’s luck and counseled me “quit while you are ahead.” But, I resonated with the creative optimism of Lawrence and Teller. I had no fear of failure. Foster’s rule was if you don’t fail half the time, you aren’t trying hard enough. His dynamic spirit inspired Livermore. “You can excel! I want to run so fast anything the Soviets build will be obsolete.”38
Riding the wave of this initial success, Nuckolls and his assistants immediately set out to refine and optimize the Ripple design, beginning work on the Ripple II and Ripple III devices.
The JTF-8’s report to the AEC discussed the nature of Pamlico and underscored its significance:
[Pamlico] was a test of a new concept. . . . This event, the final event in the Christmas Island Air Drop Series, was a physics investigation [deleted]. . . . It [End Page 146] was a highly experimental [deleted] device, designed and built by the Lawrence Radiation Laboratory in a month’s time. . . . It is felt that this shot, through further design experimentation, may lead to warheads of higher yield [deleted].
The objectives of the Ripple concept were to investigate new ranges of yield-to-weight ratio possibilities in the design of high yield thermonuclear war-heads. . . . The very gratifying results opened up new ranges of possibilities in the design of high yield thermonuclear warheads.39
A letter dated 10 August 1962 from AEC Chairman Seaborg sheds further light on Pamlico, highlighting the radical nature of the Ripple device:
The [Ripple] device, discussed in my letter to the President, deserves additional comments. To achieve the highest possible yield-to-weight ratios in nuclear weapons, high potential thermonuclear fuels must be burned efficiently [deleted].
Based on the success of the Pamlico test [deleted] the Lawrence Radiation Laboratory has indicated that the [Ripple] fuel system designs can be refined and, with further testing, produce prototype weapons [deleted].
The Pamlico event was a test of unique advanced principles relating to high efficiency thermonuclear burn resulting from [deleted]. Preliminary data indicates that the [Ripple] device performed about as predicted. With further testing, the [Ripple] concept may be applied to future weapon design and thus provide appreciable improvements in thermonuclear weapon efficiencies.40
Pamlico was intended to be the last airdrop of Operation Dominic, but an unforeseen event altered the situation just two weeks later:
During the evening of July 25, 1962, a Thor IRBM [intermediate range ballistic missile] was destroyed and burned on the pad on Johnston Island. There came then an approximate two-month interval of no testing at Johnston Island, which allowed the laboratories to think a little bit more about their problems in developing high-yield devices.41
This accident occurred during the Bluegill Prime high-altitude-effects shot. The Thor missile, which was to carry a W-50 nuclear warhead to an altitude of 160,000 feet, exploded on the launch pad and destroyed the [End Page 147] launch complex, contaminating the area with plutonium.42 The cleanup and reconstruction halted Dominic operations for nearly two months. This development prompted the AEC’s director of military applications, Brigadier General A. W. Betts, to contact Livermore and Los Alamos on 27 July and raise the possibility of further atmospheric tests. Livermore responded with its usual enthusiasm:
On August 2, [LRL director] Foster advised Betts of the LRL desire to conduct further atmospheric detonations during Dominic. [deleted] He went on to note that the Russians had announced their intention to conduct further atmospheric tests during August, September, and October and said, “The Laboratory should make every effort to prepare and test their most useful and urgent experiments.” He added that LRL was starting the design and construction of the [Ripple II and Ripple III] devices.