A blast of heat washed over the front of Kelley’s body, going clean through him and coming out the back. It was like being in a microwave oven, as fast neutrons saturated his insides, exchanging momentum with his comparatively still hydrogen nuclei. He felt the strange tingling from gamma rays ionizing the sensitive nerve endings. A rushing noise was coming from the tank, over the whir of the stirring motor. Boiling? There was a slight tremor, moving the tank sideways very slightly, one centimeter, as it walked across the floor on its four legs. He fell backward onto the concrete floor. Dazed and confused, he got to his feet, turned off the stirrer with another push of the button, then turned it back on and ran out of the building.
Two other process workers in the same room saw a flash of blue light on the ceiling, as if a photoflash had gone off, and then they heard a dull thud. No criticality alarms went off, but they both knew that something bad had happened. They rushed to help Kelley and found him outside. He had lost control of his limbs. “I’m burning up!” he cried. “I’m burning up!” They hustled him to the emergency shower, turning off the stirrer as they passed it.
In a few minutes the medical emergency and radiation monitoring staff arrived. Kelley was in deep shock, phasing in and out of consciousness. He looked sunburned all over. By 4:53 they had him in the ambulance and headed for the lab hospital. The radiation monitors ran their Geiger counters over the tank. It was hot — tens of rads per hour. It was the remnant of a criticality in the tank, but how?
When Kelley started the stirring impeller at the bottom of the tank, it was supposed to mix the oily layer on top with the water on the bottom, and it would eventually do this, but first it started the water spinning in a circle, independent of the disc-shaped, plutonium-heavy solvent stratum. The water assumed the shape of a whirlpool, a cone-shaped depression in the middle of the tank. The solvent fell into the cone, losing its large surface area and becoming a shape favorable to fission with the neutron-reflective water surrounding it in a circle. Instantly the cone of solvent became prompt supercritical, releasing a blast of fast neutrons and gamma rays.[171] The criticality only lasted for 0.2 seconds, but in that brief spike there were 1.5 3 1017 fissions. When the two fluids mixed together under the continued influence of the impeller, the plutonium-laden solvent was diluted by the water. The plutonium nuclei became too separated from one another for adequate neutron exchange, and the criticality died off as quickly as it had started.
Kelley’s condition was dire. He was semiconscious, retching, vomiting, and hyperventilating. His lips were blue, his skin was dusky red-violet, and his pulse and blood pressure were unobtainable. He was shaking, and his muscles were convulsing uncontrollably. His body was radioactive from neutron activation.
After an hour and forty minutes, he settled down and was perfectly coherent. He was moved to a private room. The staff drew blood and tried to get an estimate of his radiation dose from counting the activated sodium-24 in the sample. He had absorbed about 900 rad from fast neutrons and somewhere between 3,000 and 4,000 rad from gamma rays. A dose of 1,000 rad was thought fatal.[172] His bone marrow had changed to inert, fatty tissue. He started having severe, uncontrollable pain in his abdomen, and he turned an ashen gray. At 35 hours after he had touched the stirrer switch, Cecil Kelley died.
The plutonium process was shut down for six weeks and the tanks were ripped out and replaced with the six-foot columns, as had been planned but put off.
Back in the 1960s, all the fuel reprocessing was not for weapons work, and all was not government-owned. There were also privately owned plants. The early startups were not large operations, but the ultimate goal was to take the spent fuel from power company reactors, extract the unused uranium, sell plutonium waste to the government, compact the fission products for efficient burial, and deprive the Canadians of a monopoly on the manufacture of medical isotopes, such as technetium-99M. Spent reactor fuel was seen as a cash cow, and not as a burden on the power industry. Fuel reprocessing was also considered a necessity for commercial breeder reactor operations, and breeders were expected to start coming online later in the decade.
The United Nuclear Corporation alone owned five plants. There was one in downtown New Haven, Connecticut, one in White Plains, New York, one in Hematite, Missouri, a research lab complete with a nuclear reactor in Pawling, New York, and a brand-new scrap uranium recovery facility in Wood River Junction, Rhode Island.
Before March 16, 1964, Wood River Junction was known for two things. It was the site of a railroad trestle washout leading to a passenger train disaster on April 19, 1873, and it was regarded the coldest spot in Rhode Island. On that day in March, the sparkling new United Nuclear Fuels Recovery Plant began operations. Its first contract was to recover highly enriched uranium from manufacturing scraps left on the floor at a government-owned fuel-element factory.[173]
The plant operated on 8-hour shifts, five days a week. Scrap material was received in 55-gallon drums as uranyl nitrate, diluted down to far-below-critical concentrations of uranium. The process to reduce the stuff down into uranium metal used the purex procedure. The incoming liquid was purified by mixing it with a solvent mixture of tributyl phosphate and kerosene, followed by adding nitric acid to strip out the uranium compounds. The uranium concentrate was then washed of kerosene residue using trichloroethylene, referred to as “TCE.”[174]
Robert Peabody, 37 years old, lived in nearby Charlestown with his wife, Anna, and their nine children, ranging from nearly 16 years to six months old, and he worked the second shift at the recovery plant. During the day, he worked as an auto mechanic, managing with two jobs to support his family. It was Friday, July 24, 1964, and Peabody had taken time off from his day job to go food shopping. It was getting close to 4:00 P.M. He dropped Ann and the dozen grocery bags at the house and took the five-minute drive to the plant.
The fuel recovery facility was a cluster of nondescript, windowless buildings, no more than three stories tall, painted a cheerful robin’s-egg blue. They were set far back from the road and surrounded by an imposing chain-link fence on a flat, 1,200-acre plot. Peabody clocked in, as usual, and changed into his coveralls.
It had been a nerve-racking week at the plant, mainly due to false criticality alarms. When processing nuclear materials, working with highly enriched uranium in aqueous solutions was about as dangerous as it could get, and an accidental criticality was something to be avoided at all costs. Wednesday he had been working on the second floor, washing down some equipment, when the criticality alarm sounded. Having it blare off nearby was like having a tooth drilled. He and the other four workers left the building in a hard sprint. It took a while to figure out that there was no danger, and that water had splashed into some electrical contacts. The radiation-detection equipment was set to be nervous and sensitive to the slightest provocation.
171
I remind the reader that “prompt” supercriticality means that the mass of plutonium plus moderator is sufficiently supercritical to begin increasing the rate of fission exponentially without waiting for the delayed fission neutrons to contribute.
172
The radiation dose specification of “rad” (Radiation Acquired Dose) used in the official reports is now considered obsolete. It is often expressed in “rem” (Roentgen Equivalent Man,” because radiation counters are calibrated in rem, but that specification has been replaced with the sievert by the
173
This material was probably MTR fuel scraps from Oak Ridge. The Materials Test Reactor (MTR) was built at the Nuclear Reactor Test Station in Idaho and started up in March 1951. Its fuel was a unique design, made of bomb-grade uranium metal, enriched to 93 % U-235. The uranium was mixed with pure aluminum to make an alloy, formed into a long rod, and clad in a layer of pure aluminum, or “aluminum 1000.” The rod was then flattened between two steel rollers and bowed slightly along the major axis. This simple fuel-element design became an international standard, and “MTR fuel” was used in dozens of research reactors all over the world. As these aged reactors are decommissioned, particular care is taken to see that the highly enriched uranium fuel does not fall into the wrong hands.
174
The trichloroethylene (TCE) used in the wash-out step is incorrectly referred to as trichlorethane (chlorothene) in