The Fathom-Five Shot and the Unwashable Mist

The first Geiger counter readings were taken near the target fleet, a faint signal beneath the official pronouncements of success. The numbers were low. The numbers were manageable. Admiral Blandy’s staff assured the press that the readings fell within the safety tolerances the radiological safety section had established in the weeks before Able. But the counters had been built to detect the gamma rays flung outward by an airburst, the kind of radiation that dispersed with wind and rain and the simple passage of hours. No one had calibrated them for what Baker would produce.

At 0800 on 25 July 1946, the lagoon at Bikini lay flat and pale under a high tropical sun. The target fleet rode at anchor in a rough oval three miles wide, ninety ships of every type the Pacific war had produced. The Saratoga, a carrier that had survived the worst of the fighting, sat at the center of the formation. The Independence, a light carrier, lay a thousand yards to her starboard. The battleship Nagato, the only Japanese battleship to survive the war afloat, rode at the northern edge of the array. Submarines and destroyers, transports and oilers and landing craft, all of them waited in the stillness, their decks scrubbed, their crews reduced to skeleton parties, their guns trained on nothing.

Beneath the hull of LSM-60, a landing ship anchored in the exact center of the target array, a plutonium bomb hung suspended in the water. The bomb was known as Helen of Bikini. It had been lowered from the deck of the landing ship on cables that ran through the well deck, and it now rested ninety feet below the surface, halfway to the bottom in water that was one hundred and eighty feet deep. The cables had been checked and rechecked. The detonation circuit had been tested. The photographers on the observation ships had their cameras trained on the water where LSM-60 floated, a small gray shape in the middle of the vast fleet.

The calm was the strangest part. Aerial Test Able had been a spectacle, a bomb falling from a Superfortress, a flash in the sky, a cloud that rose and spread and dissipated. The men who watched Able had seen something they could understand: a weapon delivered from above, like a bomb from any other aircraft. Baker would be different. Baker would come from below.

At 0835, the bomb detonated.

The water beneath LSM-60 turned white. A column of spray and steam erupted from the lagoon, rising faster than the eye could follow, a million tons of water thrown upward by the force of the blast. The column climbed past five hundred feet, past a thousand, past a mile. At its base, the water churned and boiled. At its top, the spray spread into a cloud that caught the morning light and held it.

The ships nearest the center of the blast were lifted bodily from the water. The Saratoga rose and fell, her flight deck buckling, her aircraft thrown into the sea. The Independence shuddered and rolled. The Nagato, a thousand yards from surface zero, took the wave broadside and heeled far over before righting herself.

Then the column collapsed.

The water fell back into the lagoon, and as it fell, it carried with it everything the bomb had produced: fission products, unburned plutonium, neutron-activated isotopes from the bomb casing and the water itself. The spray that rose from the collapsing column was no ordinary water. A mist of radioactive particles hung in the air, fine enough to drift, heavy enough to settle on every surface it touched.

The base surge began to move.

It rolled outward from the center of the blast, a wall of mist that rose from the lagoon and advanced across the target fleet. The men on the observation ships, miles away, saw it coming: a gray-white cloud that spread low across the water, moving with the wind, swallowing the ships one by one. The Saratoga disappeared into it. The Independence disappeared. The Nagato, the submarines, the destroyers, the oilers, all of them vanished into the mist.

The base surge erupted from within the lagoon itself, a mixture of water droplets and radioactive particles that carried the products of the fission reaction outward in a way that no airburst could. The Wilson cloud that had formed after Able was a meteorological event, clean air condensing around the shock wave. The base surge was a radioactive aerosol, and it coated everything it touched.

On the decks of the target ships, the mist settled and left behind a fine residue. It seeped into the ventilation systems. It collected in the corners of gun turrets and the seams of wooden decks. It coated the aircraft on the Saratoga’s flight deck, the guns on the Nagato’s turrets, the hulls of the submarines that had been moored alongside their tenders. When the mist finally dissipated, carried out to sea by the lagoon’s internal currents, the ships were still there. They looked, from a distance, exactly as they had looked before.

They were not.

The first Geiger counter readings were taken within an hour of the detonation. The radiological safety officers, under the direction of Colonel Stafford Warren, had positioned monitoring teams on the support ships that ringed the target fleet. The teams had been trained to measure the gamma radiation that came from fission products, and they had been equipped with instruments that could detect the faintest traces of contamination.

The readings were not faint. They were high. They were, in some places, far higher than anything the safety section had anticipated. The decks of the Saratoga registered levels that would have been dangerous to a man standing on them for more than a few minutes. The Independence, closer to the center of the blast, registered levels that were higher still. The water in the lagoon, sampled by the monitoring teams, contained radioactive material in concentrations that no one had predicted.

The contamination was not confined to the target ships. The base surge had carried radioactive particles onto the decks of the support ships as well, the vessels that had been stationed outside the target array to observe and record. The men on those ships had watched the column rise and the mist roll toward them, and they had assumed that distance would protect them. The Geiger counters told a different story.

The task force had a plan for decontamination. The plan had been developed in the weeks after Able, when the first traces of radioactivity had been detected on the target ships and the decision had been made to proceed with Baker despite the warnings of the safety section. The plan called for fire hoses, for scrub brushes, for crews in protective clothing who would wash down the decks and hulls of the contaminated ships. The plan assumed that the contamination was superficial, that it could be removed with water and detergent, that the ships could be made safe for inspection and salvage.

The plan did not survive the first day.

On 26 July, crews were sent aboard the least contaminated ships to begin the washdown. They rigged fire hoses and sprayed seawater across the decks. They scrubbed the surfaces with brushes and soap. They pumped the contaminated water back into the lagoon, where it dispersed and diluted and, presumably, ceased to be a problem.

The Geiger counters did not agree. The readings on the Saratoga’s flight deck, taken before the washdown, had been high. The readings taken after the washdown were higher. The water had not removed the contamination. It had spread it. The radioactive particles, carried in the base surge, had not simply settled on the surfaces of the ships. They had bonded to the metal, worked their way into the seams and the crevices, dissolved into the paint and the rust. The hoses washed away the loose material and left the rest behind, and the water itself, as it ran across the decks and into the scuppers, carried the contamination into every corner of the ship.

The crews on the Saratoga wore protective clothing and respirators, but the clothing was not designed for the level of contamination they encountered. The respirators filtered out particles, but the particles were everywhere: on the ladders, on the handrails, on the tools the men used to scrub the decks. By the end of the first day, the monitors had detected radioactive material on the skin and clothing of the washdown crews. The men were sent back to their support ships and told to shower and change. The showers did not remove the contamination. The clothing, when it was tested, was radioactive.

The radiological safety section, based aboard the hospital ship USS Haven, began to compile the data. Colonel Warren and his staff had been warning since Able that the target fleet was too contaminated to be boarded safely, that the decontamination procedures were inadequate, that the schedule for the third test, Charlie, a deep-water shot planned for 1947, was unrealistic given what they were learning. The warnings had been noted. The schedule had not changed.

By the end of July, the evidence was impossible to ignore. The Saratoga, the most heavily contaminated of the major ships, was emitting radiation at levels that made it dangerous for any crew to remain aboard for more than a few hours. The Independence was in a similar condition. The Nagato, the German cruiser Prinz Eugen, the submarines, the destroyers, all of them registered levels that exceeded the safety standards the task force had established.

The standards themselves were a problem. The task force had set its safety thresholds based on the assumption that the contamination would be short-lived, that the fission products would decay quickly, that the ships could be cleaned and returned to service or sunk in deep water without further risk. The readings from Baker suggested that the contamination would persist for weeks, for months, for years. The isotopes that had been created in the blast, the strontium and cesium and ruthenium, had half-lives measured in decades. They would not decay in time for the Navy’s schedule.

The decontamination effort continued for weeks. Crews were sent aboard the target ships in rotating shifts, their time limited by the readings on their personal dosimeters. They scrubbed and hosed and scrubbed again. They removed the paint from the decks and the bulkheads, hoping to strip away the contamination with it. They pumped seawater through the ventilation systems and flushed the bilges. The readings fell, slowly, in some places. In others, they did not fall at all.

The Saratoga was the worst. The carrier had been at the center of the target array, and the base surge had coated her from bow to stern. The contamination had worked its way into the hangar deck, the engine rooms, the crew’s quarters. The washdown crews could not reach the interior spaces without exposing themselves to levels of radiation that the safety section considered unacceptable. The ship was too contaminated to salvage, too contaminated to sink in shallow water, too contaminated to leave in the lagoon where the tides and currents would carry the radioactive material to the beaches of the atoll.

The Navy’s solution was to tow the Saratoga to deep water and sink her. The same solution was applied to the Independence, the Nagato, the Prinz Eugen, and the other heavily contaminated ships. The ships that could not be decontaminated were taken out beyond the reef and sent to the bottom with their radioactive cargo still aboard. The ships that could be cleaned, or that were considered valuable enough to justify the effort, were kept in the lagoon and subjected to further washdowns.

The distinction between the two groups was not always clear. The decisions were made by committees, by officers who weighed the cost of decontamination against the value of the ship, by administrators who consulted the readings and the schedules and the budgets. The Saratoga, a veteran of the Pacific war, was expendable. The Nagato, a trophy of the Japanese surrender, was expendable. The submarines and the destroyers and the transports were expendable. The ships that were kept, the Nevada and the Arkansas and the few that the Navy considered worth saving, were kept because someone had decided that their value exceeded the cost of cleaning them.

The men who did the cleaning paid a different price. The washdown crews, the monitoring teams, the sailors who had been assigned to the target fleet, absorbed radiation in doses that the safety section recorded and the task force acknowledged and the Navy, in the years that followed, would struggle to explain. The dosimeters recorded the exposures. The medical records documented the symptoms. The connection between the two, between the contamination of the ships and the health of the men who had cleaned them, was a matter for later investigation, for the hearings and the studies and the claims that would come.

In the weeks after Baker, the lagoon at Bikini was a different place. The water that had been clear and blue was clouded with radioactive particles. The ships that had ridden at anchor in perfect formation were scattered, some sunk, some towed away, some still floating but too dangerous to board. The beaches of the atoll, where the Bikinians had lived for generations, were contaminated by the spray that had drifted ashore. The fish that swam in the lagoon carried radioactive material in their flesh. The coconuts that grew on the palms contained isotopes that had been absorbed through the roots.

The task force had come to Bikini to test the effects of atomic weapons on ships. It had succeeded. It had gathered data on the blast effects of an underwater detonation, on the damage that a column of water and steam could inflict on a fleet, on the way that a base surge could spread contamination across a target array. The data was valuable. The data was what the Navy had wanted.

The data was also a warning that no one had anticipated. The contamination from Baker proved persistent and pervasive, a problem the Navy’s procedures could not solve. The hoses and the scrub brushes and the protective clothing were inadequate. The safety standards were too low. The schedule was too tight. The ships that had been contaminated could not be cleaned, and the men who had tried to clean them had been exposed to radiation that no one had measured accurately.

The USS Saratoga was towed out of the lagoon on 25 August 1946, a month after the Baker shot. She had been at Bikini since the beginning of the operation, one of the first ships to be assigned to the target fleet. She had survived the war, survived Able, survived the base surge that had coated her decks with fission products. She had been washed and scrubbed and monitored and washed again. The readings on her flight deck were still high when the tugs took her in tow. The water that ran off her hull as she moved through the channel was still radioactive.

The Saratoga was sunk in deep water off Bikini, her radioactive cargo still aboard. The Navy recorded the sinking and filed the report and moved on to the next problem. The ship was gone. The contamination was not. It was in the water, in the sediment, in the fish and the coral and the coconuts. It was in the bodies of the men who had cleaned her decks. It was in the records that the safety section had compiled, the readings that showed what the hoses could not wash away.

The lagoon at Bikini was still radioactive when the task force began to pack up and go home. The ships that remained were too contaminated to salvage. The beaches were too contaminated to visit. The atoll itself, the ring of coral and sand that had been home to the Bikinians for generations, was too contaminated to return to. The Navy had come to test its weapons and had succeeded. The cost of that success was still being calculated.