which delayed production, but all twenty-one racks had begun enriching uranium by March. Juggling the different enrichment processes to produce maximum output in minimum time then became a complex mathematical and organizational challenge. Lieutenant Colonel Kenneth D. Nichols, Groves' talented and long-suffering assistant, worked out the scheduling. Based on Nichols' schedule Groves decided in mid-March not to build more Alpha calutrons, as Lawrence had proposed, but to construct instead a second gaseous-diffusion plant and a fourth Beta plant. Though he certainly expected his atomic bombs to end the war, Groves seems to have justified the new construction by the Joint Chiefs' conservative estimate that the Pacific war would end eighteen months after the European; his new plants could not be completed before February 15, 1946, he explained in his proposal, but “on the assumption that the war with Japan will not be over before July, 1946, it is planned to proceed with the additions to the two plants unless instructions to the contrary are received.” Perhaps he was simply being prudent.
Early in 1945 Oak Ridge began shipping bomb-grade U235 to Los Alamos. Between shipments Groves took no chances with a substance far more valuable gram for gram than diamonds. Although the Army had condemned all the land and ejected the original inhabitants from the Clinton reservation area, at the dead end of a dusty reservation back road cattle grazed in a pasture beside a white farmhouse. A concrete silo towered over the road, which was sheltered by a steep bluff. From the air the scene resembled any number of small Tennessee holdings, but the silo was a machine-gun emplacement, the farm was manned by security guards, and built into the side of the bluff a concrete bunker shielded a bank-sized vault completely encircled with guarded walkways. In this pastoral fortress Groves stored his accumulating grams of U235. Armed couriers transported it as uranium tetrafluoride in special luggage by car to Knoxville, where they boarded the overnight express to Chicago. They passed on the luggage the next morning to their Chicago counterparts, who held reserved space on the Santa Fe Chief. Twenty-six hours later, in midafternoon, the Chicago couriers debarked at Lamy, the stranded desert way station that served Santa Fe. Los Alamos security men met the train and completed the transfer to the Hill, where chemists waited eagerly to reduce the rare cargo to metal.
Plutonium production at Hanford depended as much on chemical separation as it did on chain-reacting piles. The chemistry was Glenn Sea-borg's, spectacularly scaled up a bilUonfold directly from his team's earher ultramicrochemical work. The plutonium in the slugs irradiated in the Hanford piles emerged mixed to the extent of only about 250 parts per million with uranium and highly radioactive fission products. Carrier chemistry — the fractional crystallization of Marie Curie and Otto Hahn — was therefore required to help the scant plutonium along. The man-made metal is extremely poisonous if ingested but only mildly radioactive. To make it safe to handle it also needed to be purified to less than 1 part in 10 million of fission products. And because the pile slugs developed such a burden of radioactivity, all but the final chemical processing had to be carried out by remote control behind thick shielding.
Seaborg's team developed two separation processes to take advantage of the different chemistries of plutonium's several different valence states. One process used bismuth phosphate as a carrier; the other used lanthanum fluoride. Bismuth phosphate, scaled up directly from Met Lab experiments, served the primary purpose of uranium and fission-product decontamination. Lanthanum fluoride, applied at pilot scale at Oak Ridge, then concentrated the plutonium from the large volume of solution in which it was suspended.
Hanford was the largest plant Du Pont had ever constructed and operated; not least among its facilities were the chemical separation buildings. “Originally eight separation plants were considered necessary,” writes Groves, “then six, then four. Finally, with the benefit of the operating experience and information obtained from the Clinton semi-works, we decided to build only three, of which two would operate and one would serve as a reserve.” For safety the plants went up behind Gable Mountain ten miles southwest of the riverside piles. Each building was 800 feet long, 65 feet wide and 80 feet tall, poured-concrete structures so massive the workers called them Queen Marys; the British ocean liner of that name was only a fifth again as long. The Queen Marys were essentially large concrete boxes, says Groves, containment buildings “in which there were individual cells containing the various parts involved in the process equipment. To provide protection from the intense radioactivity, the cells were surrounded by concrete walls seven feet thick and were covered by six feet of concrete.”
Each Queen Mary contained forty cells, and each cell's lid, which could be removed by an overhead crane that rolled the length of the building's long canyon, weighed 35 tons. Irradiated slugs ejected from a production pile would be stored in pools of water 16.5 feet deep to remain until the most intense and therefore short-lived of their fission-product radioactivities decayed away, the water glowing blue around them with Cerenkov radiation, a sort of charged-particle sonic boom. The slugs would then move in shielded casks on special railroad cars to one of the Queen Marys, where they would first be dissolved in hot nitric acid. A standard equipment group occupied two cells: a centrifuge, a catch tank, a precipitator and a solution tank, all made of specially fabricated corrosion-resistant stainless steel. The liquid solution that the slugs had become would move through these units by steam-jet syphoning, a low-maintenance substitute for pumps. There were three necessary steps to the separation process: solution, precipitation and centrifugal removal of the precipitate. These would repeat from equipment group to equipment group down the canyon of the separation building. The end products would be radioactive wastes, stored on site in underground tanks, and small quantities of highly purified pluto-nium nitrate.
Once the Queen Marys were contaminated with radioactivity no repair crews could enter them. Equipment operators had to be able to maintain them entirely by remote control. The operators trained at Du Pont in Delaware, at Oak Ridge and on mockups at Hanford, but the engineer in charge, Raymond Genereaux, sought more authoritative qualification. And found it: he required his operators, one hundred of whom arrived at Hanford in October 1944, to install the process equipment into the first completed separation building by remote control, pretending the canyon was already radioactive. They did, awkwardly at first but with increasing confidence as practice improved their remote-manipulation skills.
“When the Queen Marys began to function,” Leona Marshall remembers, “dissolving the irradiated slugs in concentrated nitric acid, great plumes of brown fumes blossomed above the concrete canyons, climbed thousands of feet into the air, and drifted sideways as they cooled, blown by winds aloft.” B-pile slugs traveled by rail into the 221-T separation plant beginning on December 26, 1944. “The yields in the first plant runs… ranged between 60 and 70 per cent,” Seaborg notes proudly, and “reached 90 per cent early in February 1945.” Lieutenant Colonel Franklin T. Matthias, Groves' representative at Hanford, personally carried the first small batch of plutonium nitrate by train from Portland to Los Angeles, where he turned it over to a Los Alamos security courier. Thereafter shipments — small subcritical batches in metal containers in wooden boxes — traveled in convoy by Army ambulance via Boise, Salt Lake City, Grand Junction and Pueblo to Los Alamos.
Bertrand Goldschmidt, the French chemist who worked with Glenn Seaborg, puts the Manhattan Engineer District at the height of its wartime development in perspective with a startling comparison. It was, he writes in a memoir, “the astonishing American creation in three years, at a cost of two billion dollars, of a formidable array of factories and laboratories — as large as the entire automobile industry of the United States at that date.”
One of the mysteries of the Second World War was the lack of an early and dedicated American intelligence effort to discover the extent of German progress toward atomic bomb development. If, as the record repeatedly emphasizes, the United States was seriously worried that Germany might reverse the course of the war with such a surprise secret weapon, why did its intelligence organizations, or the Manhattan Project, not mount a major effort of espionage?
Vannevar Bush had raised the question of espionage with Franklin Roosevelt at their crucial meeting on October 9, 1941, when Bush apprised the President of the MAUD Report, but the OSRD director got no satisfactory answer, probably because the United States was not yet a belligerent. Groves in his memoirs passes the buck to the existing intelligence agencies — Army G-2, the Office of Naval Intelligence and the Office of Strategic Services, the forerunner of the CIA — and attributes the inadequacy of their information to “the unfortunate relationships that had grown up among [them].” Why he failed to confront the issue himself until late 1943, when George Marshall asked him directly to do so, he chooses not to say. One reason was certainly security, a Groves obsession; in order to know what to look for, intelligence agents would have to be briefed on at least isotope-separation technologies and nuclear-fission research, which would mean that any agent captured or turned might well give American secrets away. When Groves finally did take responsibility for intelligence gathering he picked scientific personnel who had not worked within the Manhattan Project and authorized paramilitary operations to advance only into areas already occupied. That at least is how he intended his intelligence unit to operate; in practice it frequently claimed its prizes in the no-man's-land between fighting fronts, by hook or by crook.
The unit Groves authorized in late 1943 somehow acquired the name Alsos, Greek for “grove” and thus
