Project Y: the Los Alamos Story - David Hawkins
David Hawkins - Project Y: the Los Alamos Story, pp.224-25.
Use of polonium for the implosion initiator was a major technical achievement that involved a lot of basic research into its chemical and "metallurgical" properties. Investigation of polonium might be said to be as novel as that of plutonium.
The main problems were to prepare pure enough polonium to meet the neutron background tolerance, to prepare high-density uniform foils, and to coat those foils against polonium and alpha-particle escape. This work was hazardous because of polonium's high alpha activity and extreme mobility. It is virtually impossible to work with polonium and avoid introducing it into the human body. It is eliminated rapidly, however, and does not settle in dangerous concentrations in the bone, as do radium and plutonium. The full extent of the polonium hazard can only be determined with time. Pragmatic safety rules were intended to minimize and detect polonium absorption. Persons with more than a tolerance dose were removed from possible contact with the material until their urine counts dropped below tolerance level.
After the first half-curie, which was recovered from residues from radon capsules, the polonium used at Los Alamos was obtained from bismuth irradiated in the Clinton pile. Polonium was separated from the bismuth at two plants of the Monsanto Chemical Company in Dayton, Ohio. It was deposited on platinum foils and shipped to Los Alamos in sealed containers. Migration of the polonium off these foils onto the walls of the container caused much trouble, however.
Polonium purification was primarily Monsanto's responsibility, although there was some research on chemical purification and purification by distillation at Los Alamos.
Use of polonium for the implosion initiator was a major technical achievement that involved a lot of basic research into its chemical and "metallurgical" properties. Investigation of polonium might be said to be as novel as that of plutonium.
The main problems were to prepare pure enough polonium to meet the neutron background tolerance, to prepare high-density uniform foils, and to coat those foils against polonium and alpha-particle escape. This work was hazardous because of polonium's high alpha activity and extreme mobility. It is virtually impossible to work with polonium and avoid introducing it into the human body. It is eliminated rapidly, however, and does not settle in dangerous concentrations in the bone, as do radium and plutonium. The full extent of the polonium hazard can only be determined with time. Pragmatic safety rules were intended to minimize and detect polonium absorption. Persons with more than a tolerance dose were removed from possible contact with the material until their urine counts dropped below tolerance level.
After the first half-curie, which was recovered from residues from radon capsules, the polonium used at Los Alamos was obtained from bismuth irradiated in the Clinton pile. Polonium was separated from the bismuth at two plants of the Monsanto Chemical Company in Dayton, Ohio. It was deposited on platinum foils and shipped to Los Alamos in sealed containers. Migration of the polonium off these foils onto the walls of the container caused much trouble, however.
Polonium purification was primarily Monsanto's responsibility, although there was some research on chemical purification and purification by distillation at Los Alamos.