Operation Crested Ice

On Jan. 21, 1968, an aircraft accident involving a United States Air Force B-52 bomber occurred near Thule Air Base in the Danish territory of Greenland. The B-52, carrying four thermonuclear weapons, was on an alert mission over Baffin Bay, when a cabin fire forced the crew to abandon the aircraft before they could carry out an emergency landing at Thule. The bomber crashed onto the sea ice of the North Star Bay causing the high-explosives component of the weapons to explode, rupturing and dispersing the nuclear payload across the surface of the ice. Within hours, the Air Force activated the Strategic Air Command (SAC) Disaster Control Team and began a massive effort to recover all the contaminated debris – an operation known as “Crested Ice.”

Livermore’s involvement in the cleanup effort began almost immediately. While the hydrogen bombs on the B-52 were not of Livermore design, the Lab had recently developed and field tested a new portable scintillation counter that was designed to rapidly survey large areas. The instrument, called FIDLER (Field Instrument for Detection of Low Energy Radiation), had been developed by the Lab’s Hazards Control Department following a previous aircraft incident near Palomares, Spain in 1966, in case of another such emergency.

The Laboratory immediately notified the Air Force of FIDLER’s availability and an invitation to Thule was issued to the Lab’s “Hot Spot” team leader Nate Benedict and physicist Joe Tinney on Jan. 24. The two Lab employees were given only a few hours to prepare for departure and make the necessary modifications to the FIDLER to enable it to withstand the minus 40-degree temperatures at the site. Hazards Control technicians and shop personnel hurriedly assembled what turned out to be a very workable heat shield, and Benedict and Tinney left SAC Headquarters in Omaha, Nebraska for Greenland aboard a KC-135 aircraft loaded with 1,500 lbs. of raw horsemeat being rushed to the site for the sled dogs serving in the operation.

When Livermore’s Benedict and Tinney arrived at Thule, the crash site was still in a primitive state. Support facilities consisted of a wooden shack, and the only light in the constant darkness came from Coleman lanterns – a state that Tinney described as “depressing.” However, with help from the Air Force, the pair were able to get the FIDLER calibrated and begin their assignment of surveying the impact area to plot the distribution of the contamination. The FIDLER instrument performed admirably, and early measurements indicated its usefulness for all subsequent cleanup and decontamination plans for the site.

Aside from the natural difficulties of the site, Benedict and Tinney faced other basic critical issues in just keeping the FIDLER unit operating in the harsh conditions. However, they were soon aided with the arrival of Livermore electrical technician Don Knowles, who arrived with testing equipment, spare parts and two additional FIDLER units. By the time their initial assignment was complete, the Livermore team proved itself so useful that Gen. Richard Hunziker, the SAC officer in charge of the clean-up operation, requested replacement personnel from the Lab.

Benedict left Thule on Feb. 1 and was relieved by Hazards Control department head Jim Becker, along with additional other Lab personnel. As Hunziker related: “your organization was splendidly represented by this fine group, and I am deeply grateful for these scientists and to your organization for your very real help during this difficult project.”

Following the aircraft accidents at Palomares and Thule, both the Livermore and Los Alamos laboratories continued their work into the study of insensitive high explosives (IHE) to improve the safety and security of nuclear weapons. Livermore researchers published their first report on investigations of an IHE called TATB (triamino-trinitrobenzene) in 1975. Additional work to characterize the material and find improved ways of producing it led to widespread use of IHE in nuclear weapons.

Pictured: Members of the nuclear clean-up crew at work near Thule Air Base, 1968.