Atomic Accidents, page 12
50 The Japanese battleship was the Nagato, carefully placed in the array so that it would be certain to sink. It had been the command ship from which the Pearl Harbor attack was directed back in 1941, and to sink it with an A-bomb was symbolic. It was a well-built ship, and two nuclear devices failed to send it to the bottom. The target point was the battleship Nevada, a survivor of Pearl Harbor. It was painted red so that the bombardier could see it (not likely in warfare), but they missed it by 710 yards, putting the bomb on top of a lowly transport ship, the Gilliam.
51 Not really. At the Los Alamos Lab there were also the Topsy and the Jezebel assemblies. These specialized devices may have been better designed, as no unplanned criticalities were ever reported for them. The French were conducting similar experiments at about the same time, first at Saclay with the PROSERPINE and ALECTO assemblies and then after 1961 at the Valduc Research Centre using the CASTOR and POLLUX machines (rig B and rig D). No accidents were recorded.
52 The uranium assembly built in 1952 was named “Jemima.” The Mk-8 uranium bomb was already deployed by then. Jemima was probably the W-9 280mm artillery shell, being handed over to the Army that month.
53 Lockheed Nuclear Products received the go-ahead to build a Godiva II on an aluminum railcar for use at the Georgia Nuclear Aircraft Laboratory in 1957. This plutonium “pulse reactor” was supposed to simulate a nuclear weapon explosion below the nuclear-powered bomber as it flew away after a drop. Would the radiation pulse confuse the engine instruments and cause a scram in the aircraft? I find no record of its use nor accident reports.
54 There was also a “mini-Godiva” for portable use by weaponeers. An aluminum Halliburton case was filled top and bottom with paraffin, with cutouts shaped to fit the target-piece for a uranium assembly weapon. A BF3 neutron detector and a fixed neutron source were also embedded in the paraffin, with a cable connection for the counter electronics in another Halliburton. The target was made of little uranium discs that would screw together into a cylinder. In the field it could be shimmed to the proper level of activity by adding or subtracting discs. The specialist would lay the cylinder in the paraffin nest, close the case, and push a button on the neutron counter. After counting neutron hits for a minute, the activity level of the target was evaluated using the results.
55 Perhaps. I actually don’t know what he was thinking, but the metaphor was too thick not to use it.
56 Technically, he absorbed 4,500 rad of neutron radiation and 350 rad gamma rays. The rad is an obsolete measurement that does not take into account the “Q,” or the radiation quality factor and how it affects humans. Assume a Q of one, and he got a body dose of at least 4,850 rem. It was probably closer to 40,000 rem or 400 sieverts, which would drop an elephant.
57 If you are amazed by some of the detailed information available concerning Soviet nuclear work, read an example of glasnost in the Proceedings of ICNC’95, Vol. 1, pp. 4.44-4.47, “Criticality Measurements at VNIITF Review,” V.A. Teryokhin, V.V. Pereshogin, and Yu.A. Sokolov.
Chapter 3
A Bit of Trouble in the
Great White North
“A scientist need not be responsible for the entire world. Social irresponsibility might be a reasonable stance.”
—advice given to young physicist
Richard Feynman by mathematician
Johnny von Neumann
The decade of the nineteen-fifties is often cited as a dull period of time, lacking the excitement and colorful excesses of the following decade, the sixties. The sixties exploded with John Kennedy, the Beatles, recreational pharmaceuticals, space travel, and hippies. What did the fifties give us? Dwight Eisenhower and black-and-white television?
Deeper research indicates that this comparison of two decades is upside down. The utter wildness of the nineteen-fifties, a decade in which 100 new religions were formed, psychedelic drug experimentation was on an industrial scale, and vast scientific experiments outstripped science fiction, makes the sixties a wind-down.58
Eisenhower, the subdued old Republican who liked to play golf, reversed everything that his predecessor, Harry Democrat Truman, had worked so hard to nail down. He stopped Harry’s Korean War in mid-advance. He played a clever game with the Soviet Union, forcing them to be the first to orbit a satellite that passed over the United States, thus setting the international precedent for down-looking reconnaissance from space. Most surprising, he opened the files of the Manhattan Project, insisting that every document, scientific finding, and gained expertise that did not relate directly to the weapons be declassified and released to the entire world. Truman, seeing this knowledge as proprietary property of the United States government, had denied access to our most trusted allies. Even the British and the Canadians, who had participated in the development work, were allowed no access. Eisenhower wished to give all the world enough knowledge to pursue civilian-owned nuclear power. He railed at the “military-industrial complex,” warning of its desire to make profits from developing new, more advanced weaponry.
Simultaneously, this tranquil administration oversaw the rapid development of the hydrogen bomb, a weapon 1,000 times more powerful than those used to wipe out entire cities in Japan with single drops, and the exotic hardware to deliver it. Nuclear rockets capable of sending a fully equipped colony to Mars in one shot were designed. Most of the nuclear power research effort went into submarine propulsion, with civilian electrical plants a minor sub-topic. Enormous scientific and engineering development efforts, such as the nuclear-powered strategic bomber and earth-moving by atomic bombs, call into question the enthusiasm of this ten-year span. Some projects were so insanely reckless, the public perception of anything nuclear was permanently damaged.
A case in point is Castle Bravo, the code name for the first test of a practical H-bomb at Bikini Atoll in the Marshall Islands archipelago. The concept of a nuclear fusion weapon had been resoundingly confirmed on November 1, 1952, with the explosion of the Ivy Mike thermonuclear device on what used to be Elugelab Island in the adjacent Enewetak Atoll. That bomb weighed 82 tons, sat in a two-story building, and required an attached cryogenic refrigeration plant and a large Dewar flask filled with a mixture of liquefied deuterium and tritium gases. It erased Elugelab Island with an 11-megaton burst, making an impressive fireball over 3 miles wide, and the test returned a great deal of scientific data concerning pulsed fusion reactions among heavy hydrogen isotopes, but there was no way the thing could be flown over enemy territory and dropped.59
The Castle Bravo shot on March 1, 1954, tested a lighter, far more compact H-bomb named “Shrimp.” It used “dry fuel” or lithium deuteride as the active ingredient, and it needed no liquefied gases or the cryogenic support equipment, yet it gave the same deuterium-tritium fusion explosion in an “F-F-F” sequence: first a RACER IV plutonium implosion bomb (fission), followed by a large deuterium-tritium compression event (fusion), and finally a fast-neutron chain reaction in the uranium-238 tamper (fission). Sixty percent of the power from this and subsequent thermonuclear devices came not from the hydrogen fusion, but from the fission of the humble uranium tamper, a mechanical component with a lot of inertia intended to keep the bomb together for as long as possible while it exploded.
The tritium used in the fusion event was made during the explosion from the lithium component of the dull gray lithium deuteride powder.60 The light isotope of natural lithium, lithium-6, captures a surplus neutron from the explosion of the RACER trigger device and immediately decays into tritium plus an alpha particle, or a helium-4. This tritium plus the deuterium nucleus in the same molecule fuse, being caught between the severe x-ray pressure front from the fission explosion and a plutonium “spark plug” in the center of the fusion component.61
The explosive yield of this arrangement was predicted to be 5 megatons, with no possibility of exceeding 6 megatons. It could not be as efficient as the Ivy Mike device using liquid hydrogen isotopes, because the lithium was not all lithium-6. Natural, out-of-the-ground lithium is only 7.5 percent lithium-6; the rest is lithium-7. Lithium-6 has an enormous neutron activation cross section, or probability of capturing a neutron and exploding into tritium plus helium. Lithium-7 has an insignificant cross section and would not participate. With great effort, the bomb makers were only able to enrich the natural lithium to 40 percent lithium-6, and the rest would be inert and wasted.
In the week before the Castle Bravo test, the wind was blowing consistently north. That was good. Any fallout kicked up by the explosion would be blown out over a large Pacific range, empty of islands and inhabitants. Early in the morning of the test, the wind shifted, blowing east. That was bad. From 60 to 160 miles east of ground zero were inhabited islands that could be hit with a load of radioactive debris. Delaying the detonation until the wind direction improved was debated, but the operations director vetoed it. There were too many time-dependent experiments set up, and it would cost too much to interrupt the tight schedule. The countdown continued.
The Shrimp was set up on an artificial island on the reef next to Namu Island, and at 6:45 local time it was detonated, becoming the first nuclear accident involving a weapon test. We will never know exactly how powerful the Castle Bravo was, because all the measuring equipment, close-in cameras, and recorders were blown away in the blast, but it is believed to be between 15 and 22 megatons, making it the biggest explosion ever staged by the United States, and much larger than what was planned for. In one second it made a fireball four and a half miles in diameter, visible on Kwajalein Island 250 miles away. The top of the mushroom cloud reached a diameter of 62 miles in ten minutes, expanding at a rate of four miles per minute and spreading radioactive contamination over 7,000 square miles of the Pacific Ocean. Did they do anything like that in the sixties? Not even close.
All hell broke loose. The Rongelap and Rongerik atolls had to be evacuated. Men were trapped in control and observation bunkers, sailors suffered beta burns, and fallout rained down on Navy ships in the area. The bomb had cleaned out a crater 6,500 feet in diameter. The coral in the reef was pulverized and neutron-activated to radioactivity, mixed with radioactive fission debris, and in 16 hours spread into a dense plume, 290 miles long and heading due east in the wind toward inhabited islands. Permanently installed testing facilities at the atoll were knocked down, and radioactive debris fell on Australia, India, and Japan. Circling the world on high-altitude air currents, the dust from the test was detected in England, Europe, and the United States. American citizens were alarmed when warned of milk contaminated with strontium-90, a major product of the uranium-238 fissions in the tamper.
What happened? The expectation of no action from the lithium-7 component of the lithium deuteride was incorrect. The neutron density in a thermonuclear bomb explosion is inconceivably large, and in this condition it does not really matter how small the activation cross section is. Neutrons will interact with the lithium-7, producing tritium, and helium-4, plus an extra neutron. All of the lithium deuteride was therefore useful in the explosion, and the yield was three times the expected strength. Not only was more energy released in the deuterium-tritium fusion, but the unexpected neutron excess increased the third-stage fission yield in the tamper, made of ordinary uranium. While the fusion process was considered clean, producing no radioactive waste products, the uranium-238 fission was unusually dirty.
A complicating problem was the choice of the Director of Operation Castle, Dr. Alvin C. Graves. As you recall from the previous chapter, he was standing close behind Louis Slotin when he made his fatal slip with a screwdriver and a plutonium bomb core went prompt critical. Graves caught 400 roentgens right in the face. He could have died easily from the acute exposure, but he lived on to rise in the ranks at Los Alamos.62 Graves therefore could see no particular problem putting men close to atomic blasts in several experiments, from the Marshall Islands tests to the above-ground explosions in Nevada.63 This peculiar tendency is similar to the case of Bill Bailey and his Radithor, noticing no ill effects from his elixir while subjecting Eben Byers to a horrible death. Both men, Graves and Bailey, endured later condemnation for exposing so many people to so much radiation.
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.
