MJW Corporation - Radiological - Polonium Dose Assesment

Radiological

Dose Assessment: Polonium 210

Our Expertise

MJW Corporation maintains a unique expertise in evaluating individuals potentially exposed to Polonium 210. During the period of 1996 to 2001 MJW was contracted through the U.S. Department of Energy, to reconstruct the internal radiation exposures for thousands of individual workers employed at the Mound Labs in Miamisburg Ohio. During the course of this dose assessment project, it was determined that the current biokinetic model for Polonium internal dosimetry was incorrect. Use of that model resulted in the calculation of lethal doses to workers who were in fact alive and well. MJW sponsored the development of a revised biokinetic model for Po-210 and created software tools which utilize this updated model to evaluate individual exposures. MJW health physics staff subsequently assessed nearly 1,000 individuals who were occupationally exposed to Po-210.

Mound Labs (and its predecessor Monsanto Chemical Corp. Dayton Laboratory) was one of the few places in the United States where polonium was of significant concern for worker exposure. Therefore, other than these dose assessments performed by MJW, there has been little focus on polonium dosimetry in humans in recent years.

Historic Use of Polonium

Polonium was first discovered and chemically separated by Marie and Pierre Curie. Marie named this strong alpha emitter after her native country of Poland. Polonium 210 was a vital component in the early years of the nuclear weapons program. It was used in conjunction with beryllium to produce neutrons, which served to initiate the fission chain reaction. Beryllium will release neutrons after absorbing an alpha particle emitted by polonium. Due to the relatively short half life of polonium-210 (138 days) the polonium in these atomic weapon triggers required frequent replacement.

Polonium had not been produced in any appreciable quantities prior to 1943. Therefore, research was required to determine the properties and metallurgy of this element. That mission was conducted at the Dayton Laboratories of the Monsanto Chemical Company. Polonium recovery was initially attempted from naturally occurring sources. However, it was later determined that production of adequate quantities could only be achieved through the neutron bombardment of bismuth.

The polonium operations were subsequently transferred to the Mound Laboratory (Miamisburg, Ohio) in 1949. In addition to producing polonium to support the US nuclear weapons program, the Mound also utilized polonium to produce radioisotope thermoelectric generators or RTGs. RTGs are used to produce electricity to operate satellites and other unmanned space vehicles.

Because of the relatively short half life of polonium, it?s usefulness in these applications was limited and was better served utilizing longer lived alpha emitters such as plutonium. Polonium operations were terminated at the Mound Labs in 1971.