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Operation WIGWAM was a deep underwater nuclear detonation conducted in the Pacific Ocean approximately 500 miles southwest of San Diego. The test occurred on May 14, 1955. The bomb was suspended by cable from an unmanned barge and detonated at a depth of 2,000 feet in water that was 16,000 feet deep. The test had a yield of 30 kilotons.

by 1955, the United States had already detonated nuclear weapons in the atmosphere, on the surface of the both the earth and water and at shallow underwater depths. The Navy wanted to conduct tests into what effects a deep underwater detonation would have if exploded at a depth that would contain all the initial energy of the blast. They were interested in how a deep underwater shot would affect naval forces, what kind of shockwave would occur, and the effects that a nuclear explosion would have on naval operations. The main question of the tests was to see if a surface vessel could use nuclear weapons to destroy submerged enemy submarines without causing harm to itself.


The Department of Defense contracted the Scripps Institution of Oceanography to survey locations in the Pacific, the Caribbean, and the Atlantic Ocean to perform the detonation. The site needed to be deep enough to contain the blast as well as far away from undersea or sea bottom perturbations, such as sea mounts, ridges, and islands. It was also essential that the site not be in migratory fishing areas and shipping lanes.

Approximately 6,800 personnel and 30 ships participated in Operation Wigwam. A 6-mile towline connected the fleet tug, USS Tawasa, and the barge from which the nuclear device was suspended. Along the towline there were different pressure ­measuring instruments, unmanned and specially prepared submerged submarine­ like hulls, and unmanned surface boats. The bomb used in the test was a B-7 (Mk-90) Betty which is a 31 kiloton depth bomb. The bomb weighed 8,250 pounds and was suspended by a 2,000 foot cable from a barge.

Ships conducting the test were positioned five miles from the barge. Two ships, the USS George Eastman and the USS Granville S. Hall were equipped with shielding and stationed downwind of the blast zone. Although nearly all personnel were issued film badges to measure radiation exposure, no protective gear was provided.


Immediately after detonation a fireball-bubble rose to a height of 12,000 feet. The eruption covered a one and a half mile area of the ocean and dispersed over 330 billion cubic feet of highly radioactive seawater in all directions. The vessels that were in close proximity to the detonation site were completely inundated by a 1,200 ft tidal surge, causing severe damage to superstructures anc destroying machinery, communication equipment, and the ships hydraulic systems.

The circle of ocean craft assembled was slammed by repeated shock waves. Some were submerged in a tidal surge that reached 800 feet above their main masts. Scientists were on board the U.S.S. Tawasa who were tasked with filming the event. The shock of the initial explosion smashed into the vessel, breaking pipes, hydraulic lines, and twisting the propeller shaft. The ship was tossed about and then completely submerged. What was left of a 30,000-foot towline served to hold the ship steady, saving it from complete destruction. The giant wave gave off a spray of atomic mist that hit every ship and observer of the blast. Official government reports describe the spray as an "insidious hazard, which turned into an invisible radioactive aerosol." Although film badges were worn by all personal, they did not measure ionizing radiation particles. The mist created by the explosion caused those in the path of the fallout to ingest and inhale these particles. The ionizing radiation has since proven to be the most harmful to personnel years after exposure.

After the ocean waters had calmed down, vessels were sent in to retrieve approximately 40 radiation sensing pods called RAP's. The RAP's were placed on the ship's fantail and along the port side main deck, which was adjacent to the ship's Galley and the crew's Mess hall. Within 12 hours, the Scripps scientists aboard the vessel declared the Galley and the Mess off-limits to all ship's personal. They had detected dangerously high levels of radiation that was penetrating the bulkhead between the main deck and the cooking and dining spaces. Other Navy personnel carried out assignments with minimal protection. Divers went deep into radioactive waters and pilots flew into the air above the blast area. These people were all exposed to secondary radiation.

Within twenty four hours of the initial test detonation there was a 9,900 foot diameter of highly radiated ocean surrounding "ground" zero. The Scripps scientists identified this as the post test "hot spot" and determined it had begun to drift slowly to the southwest. Navy Vessels were sent to track and monitor the slowly drifting hot spot. Scripps scientists took periodic samples of radiation readings a various ocean depths. It took over 40 days for radiation levels to go below the non-critical stage. There was no way of knowing how many tons of migrating fish passed through the hot spot, nor was there any way to track where they went and if they were eventually harvested and served as food. Although the area in the Pacific Ocean where the bomb was detonated was chosen because the Scripps scientists thought it to be a biological desert, eye witness reports said that after the detonation the ocean was covered with dead marine life for as far as the eye could see. The Defense Nuclear Agency's fact sheet on Wigwam reports that radioactivity in water from the 30 kiloton underwater device was found some 80 miles from the blast.

Before the Wigwam test, the Scripp's technicians placed several airborne radiation monitors from the California/Mexico border, south of San Diego, to the City of Oceanside, north of San Diego. The monitors in the greater San Diego area measured higher than normal levels of radioactivity over the city for four days after the Wigwam test. Over the next nine days the radioactivity readings continued to rise, reaching levels twenty times above the normal background levels. San Diego residents were not made aware of these developments and the information was kept top secret for decades.

After the blast, floating debris could be found scattered over a five-mile radius. The larger pieces were taken aboard ships to be transported back to shore. Weapons were used to sink smaller debris to the floor of the ocean. The submarine hulls, surface barges support platforms, and other important items were selectively retrieved and transported to San Diego. When documents relating to Operation Wigwam were later declassified, it was revealed that, largely because of adverse weather conditions, 70 percent of the experiments were failures.

After the test, one of the highly radiated submarine hulls was placed onto a barge, and a Navy Auxiliary vessel towed the barge to Long Beach harbor. Due to rough seas, the barge capsized off of Catalina Island and the radioactive submarine hull came off the barge in a popular sport fishing area. The towing vessel was given orders to sink the barge with 40mm cannon fire. Navigational charts of the region were never updated to show a sunken submarine hull or the barge. In the late 1960s, a sports diver, who was also a crewman assigned to the Navy vessel that transported the submarine hull, reported seeing the hull in the same general area where it had sunk. The U.S. Navy has no official comment on the matter.

Cancer in known participants

Captain Richard Purdy was the skipper of the U.S.S. Marion County. When hit by the tidal wave caused by the explosion, the ship's bow doors and several pieces of deck machinery were severely damaged. Since Capt. Purdy could not safely move his ship forward, he traveled in reverse for 480 miles backwards to get back to Long Beach harbor. After docking in a classified area of the harbor, Capt. Purdy was not allowed to leave. A technician from the Scripps Institute checked him for radiation and found his shoes were too "hot" to allow him to leave his vessel. A few years after Operation Wigwam, Purdy was diagnosed with leukemia and lung cancer. He died shortly after.

Tom McCarthy was a navigator stationed on the bridge of the Mount McKinley. In addition to being present for the detonation, he was at that site for the four following days. Years later, at the age of 36, McCarthy was sick with undiagnosed symptoms. He died from radiogenic cancer at the age of 44. Although he had multiple forms of cancer, including thyroid, pancreatic, lymph, liver, and others, the primary cause of death on his death certificate was lung cancer. There had been no history of cancer in McCarthy's family and none of his relatives had died of cancer after him. In 1994, McCarthy's wife Joan testified before the Advisory Committee on Human Radiation Experiments. She said that before her husband's death he told her about his involvement in Operation Wigwam and his belief that it is what caused his cancer. He had only been diagnosed four months prior to his death.

Search for the Truth

R.J. Ritter was a crewmember on the USS Tawasa. As a member of the National Association of Atomic Veterans, he researched the aftermath of Operation Wigwam. This was a difficult task since everyone involved with the operation was required to sign a 25 year non disclosure and secrecy agreement. If the agreement was violated, the person could face incarceration. Ritter claims that even though the time limit has passed, most of the Operation Wigwam survivors are not speaking out about their involvement in the test. According to Ritter, "The planners major concerns were focused on the scientific and military results of the test. Any concerns for the possible hazards facing thousands of men involved first hand and stationed at the blast site, seemed at the time to be secondary in nature. In fact, the Navy was more concerned about their original proposal to stage a much larger operation. But, that event had to be scaled down because of a somewhat restricted budget."

In 1980, the Center for Investigating Reporting in Oakland wrote an article about the test titled "Operation Wigwam: The Story of California's secret Nuclear War, the Enemy 6,500 Americans." The article reports that "The task force of Scripps scientists knew that what they were readying was an experiment and an experiment involving human life. The chief objective of Operation Wigwam was to determine with accuracy at what ranges, under various conditions, a submarine or surface vessel will be destroyed by a deep underwater atomic explosion, and second, to determine the hazards to the ship and supporting forces." Later it states that ""In other words, the naval personnel being assembled for the blast were unwittingly participating in a nuclear war games experiment."

In 1980, when the details of Operation Wigwam became publicly known, Governor Brown of California issued an immediate call for the federal government to publicly release the names of all servicemen involved in Wigwam, so that they could receive suitable medical treatment.


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