A medical study of Marshall Island residents, Project 4.1, was put together hastily to document the radiation injuries. The investigation found that 239 Marshallese and 28 Americans were exposed to significant but non-fatal levels of radiation. The final report was classified SECRET, “due to possible adverse public reaction.”[64]
Over-yield of the Castle Bravo device was frightening to many who worked on it, but the real tragedy unfolded far west of the test site, in Japan. It is called the “Lucky Dragon Incident,” and its everlasting effect on the public’s perception of nuclear radiation was outside the control of the test program. It would mark in history the first and last record of a death caused by a United States nuclear weapon test.
The Daigo Fukuryū Maru, or the Lucky Dragon 5, was a wooden 90.7-ton Japanese fishing boat with a 250-horsepower diesel engine and a crew of 23. On March 1, 1951, she was trawling for tuna where the fishing was good and competing with 100 other Japanese fishing boats in the general area of the Marshall Islands. There had been vague warnings from the U.S. earlier that year, defining a rectangular area of hazard around Bikini Atoll and hinting at nuclear weapons tests, but no dates had been specified. The Dragon got as close as it could to the western edge of the rectangle, within 20 miles of the boundary. Tuna liked to swim near the Marshalls.
At 6:45, the sun seemed to rise in the west. The crew stopped their preparations for the day’s fishing and stared at the fireball lighting up the sky. Seven minutes later, the shock wave, reduced by distance to a mean clap of thunder, rolled over the boat. Still, the men fished. In a few hours, it began to snow, and the boat, the fishing equipment, and the men started to become covered with white flakes of coral, blasted to a fine ash by the explosion of the Shrimp over in Bikini. For three hours it fell, beginning to form drifts against the wheelhouse and impeding movement on the deck. The men started scooping it into bags with their bare hands, initially unaware that it was fallout, infused with a fresh mixture of radionuclides, but starting to get the dreaded feeling that they had witnessed a pikodon—Japanese for atomic bomb.[65] They had to get out of there fast, but first the moneymaker had to be reeled in. It took several hours to recover and stow the trawling net, with the men wiping the calcium snow out of their eyes. Thirteen days later the Dragon chugged into its home harbor in Yaizu, Japan, filled with radioactive fish.
The crew was suffering from nausea, headaches, burns on the skin, pain in the eyes, and bleeding from the gums — all symptoms of radiation poisoning, and as their boat was unloaded and their catch put on ice the men were sent to the local hospital. Several were obviously sick. For some reason the radio operator, Aikichi Kuboyama, who should have been inside and not on the deck, was in the poorest condition. The men were scrubbed down several times, their hair was shaved off, and their nails were clipped, all to remove the radioactive dust that was ground into their surfaces, but the doctors were stumped when nothing seemed to help.
News of the contaminated crew traveled fast. The entire world became interested, and there was explaining to do. In retrospect, the public relations efforts were dreadful. Lewis Strauss, head of the Atomic Energy Commission, first claimed that the fishermen’s injuries could not have been caused by radiation, they were inside the no-fish zone, and besides that it was a Soviet spy boat that had gathered classified information on the bomb test and simultaneously exposed its entire crew to radiation just to embarrass the United States. Requests from Japan for an inventory of the radioactive species in the fallout so that treatments could be specified were denied, on the grounds that the nature of the bomb could be derived from this information.[66] The extent of contamination was claimed to be trivial, in parallel with the Food and Drug Administration imposing emergency restrictions on tuna imports. The impression given to the people of Japan, still sensitive about atomic bombs, could not have been worse.
A young biophysics professor in the city university in Osaka, Yashushi Nishiwaki, read about the Lucky Dragon in the paper, and he called the health department to see if any tuna had been shipped there from Yaizu. Yes, tons of it. He took his Geiger counter down to the market and waved it over some tuna. To his alarm, the needle on his rate-meter slid off scale. He was counting 60,000 radiation events per minute. The entire catch was heavily contaminated. Even loose scales and paper wrappings of fish that had been bought and eaten by now reeked of fission products. It was headlines in the evening paper, and mass hysteria took the city, then the region, and Japan. First, the Misaki fish market closed. Fish mongers scrambled for Geiger counters so that they could run them over the fish and prove to buyers that there was no radioactivity, but it did not help. People stopped buying fish. Yokohama closed, and then, for the first time since the cholera epidemic of 1935, the Tokyo fish market closed. It was revealed that fish were banned from the Emperor’s diet, and that was it. Prices for tuna crashed, and dealers filed for bankruptcy. It would take years to recover.
Meanwhile, the Lucky Dragon fishermen were recovering, except for Aikichi the radio operator. His liver was failing. His condition worsened and he died on September 23 at the age of 40. “I pray that I am the last victim of an atomic or hydrogen bomb,” were his last words, splashed all over the news. The United States government eventually paid the widow the equivalent of about $2,800 and agreed to pay Japan, with the wrecked fishing industry, $2 million for their trouble. From this donation, each crew member was given $5,000.
Out of the disaster came Nevil Shute’s great novel, On the Beach, later made into a major motion picture starring Gregory Peck, and the entire Japanese monster movie industry, beginning November 3, 1954, with Godzilla, a city-wrecking beast mutated by contaminating radiation. The Lucky Dragon 5 was stripped down, decontaminated, and rebuilt. It was sold to the government for use as a training vessel in the Tokyo Fisheries School, renamed the Hayabusa Maru, or the Dark Falcon. Today, the Lucky Dragon 5 is preserved for all time, lest we forget, in the Tokyo Metropolitan Daigo Fukuryū Maru Exhibition Hall. The other 22 crew members all recovered with no lingering health effects from the fallout contamination.[67] As health physicists always point out, if the men had simply lowered themselves into the water and washed off the gray dust, they would not have suffered any effect from the fallout. It was the fact that it stayed on their skin for so long that caused the trouble. If they had cut loose the nets and headed north at full power, while hosing off the deck, history would be different.
These nuclear shenanigans of the United States in the early 1950s were interesting for how they helped shape the growing public angst, but they were part of a mutant off-shoot of the larger task of taming the atom for use as a power source. The weapons tests were fascinating, almost recreational, but not really helpful from a long-term, scientific perspective. The rest of the world together had a smaller research budget, but progress toward understanding nuclear reactions was being made independently and usually in secret in a few foreign countries. In the beginning, right after the Second World War, England, France, and the Soviet Union were very interested in coming up to speed, but the first nuclear reactor outside the United States was built and tested in the second largest country on Earth: Canada.
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It has been alleged that the victims of the Bravo test were purposely exposed to fallout radiation as “guinea pigs” in a radiation experiment. Micronesian Representative Ataji Balos charged that Castle Bravo was directed purposely at the inhabited Marshall Islands because the Marshallese were considered to be expendable and of marginal status in the world at large. There is nothing to support this charge. The engineers and scientists in charge of the Bravo test could not have bent the wind east if they had wanted to, and they were honestly surprised at the power of the explosion. Project 4.1 did not exist until four days after the test.
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It was possible to derive the composition of such a device from analysis of the fallout, which scientists in the Soviet Union proceeded to do without help from the AEC. There was no lack of fallout material to analyze. Measuring the percentage of one nuclide, U-237, in the fallout using a single-channel pulse-height analyzer, it was possible to deduce that Shrimp had been a three-stage F-F-F device with a U-238 tamper.
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Why was the radio operator the only one who died, and of what did he perish? Aikichi may have been a person who was more sensitive to radiation exposure than the rest of the men. Even given that, the radiation load would not have been high enough to kill him in seven months. A quiet conclusion was that he died of infectious hepatitis from the many blood transfusions he was given at the Tokyo University Hospital.