Should 210Po and 210Pb be released into the atmosphere or into surface waters. An aspect of an optimization procedure

There is a large phosphorus plant in operation in the south-west of the Netherlands. The 238U daughters 210Pb and 210Po, present in phosphate ore, are volatilized in the production process. A considerable part of the volatilized nuclides is emitted with the off-gases into the atmosphere and with off-gas washwater into the Scheldt estuary. For both emission types assessments are made of: geographical distribution, emission, deposition, inhalation doses and doses from consumption of milk, meat, crop products, fish, shrimps and mussels. When 210Pb and 210Po are emitted in equal quantities, atmospheric and effluent emissions cause approximately the same dose increases. For emissions of 3.7x1010 Bq the increase of the population dose is of the order of 10 man·Sv/a and for individuals a maximum of 10 μSv/a can be estimated. The dose increase caused by 210Pb when emitted into the atmosphere is about four times the increase due to releases into surface waters. The reverse is true for 210Po. These findings can be used in an optimization study in addition to other non-radiological factors. (author)