Twenty-year follow-up of a Pu/Am inhalation case

Abstract

In 1983 a technician inhaled a mixture of Pu/Am aerosols in an accidental situation in the hotlab of Paul Scherrer Institute (PSI). This case is of interest for long-term follow-up since the technician was relatively young (26 y) at the time of intake, no chelating agent was used to alter retention and excretion and the inhaled activity was rather high (% 20 kBq of alpha emitters). The results obtained from periodic lung counts, urinary and faecal excretions as well as from some bone and liver measurements up to the year 2003 are presented. The measurements were mainly made at PSI but also at FZK Karlsruhe, Germany, and PNNL Hanford, USA. The evaluation and dose estimation of this case was done by several institutions, such as FZK, PNNL and NRPB in addition to PSI. Elements of the case were used in international biokinetic model validation programs by EURADOS/EULEP and IAEA and the 241 Am data are given as example in Annex E of the ICRP 'Guide for the Practical Application of the ICRP Human Respiratory Tract Model'. An overview is given on the various results obtained by the different institutions using their models and methods for interpretation of the measured data. While estimation of intake varies by more than an order of magnitude, final estimation of effective committed dose varies only in the range of 0.5-1.5 Sv.

30-y follow-up of a PU/AM inhalation case

“…The Pu/Am inhalation case of 1983 has been studied by colleagues in several institutions and described in numerous papers including the publication of 2007 (1) , the actual publication and many papers cited in both publications. The aim of the full publication of all data of this case is to make this information available for internal dosimetry model evaluation and training in internal dosimetry.…”

“…A first paper describing the details of the accident, the early measurements and dose estimates of the Pu/Am inhalation case of 1983 at the former Federal Institute for Reactor Research in Switzerland has been published in 2007 (1) . Immediately after accidental inhalation by a 26-y-old male technician, dose estimates were of primary interest.…”

“…Fortunately, the person concerned accepted all these measurement procedures. Over the last few years, organ measurements were performed with highly specialised instruments at Karlsruhe Institute for Technology (KIT) (2) and the excretion measurements were done again at Paul Scherrer Institute (PSI) (1) . In addition to all the physical measurements, current cytogenetic analyses were performed at Federal Office for Radiation Protection (3) to complete scientific data by biological studies.…”

“…The reason of the discrepancy for 241 Pu is not known. As in the previous analysis, an effective AMAD (10) (Activity Median Aerodynamic Diameter) of 5 mm has been estimated from early lung and early faecal excretion data (including the activity that would have appeared in the faeces if it had not been not removed with a nasal swab and a bronchial slime before the first chest measurement was done (1) ). This value has been used to calculate the fractions of material The calibration phantom did not distinguish between lung and thoracic lymph nodes.…”

“…Up to now, the conventional analysis of dicentric chromosomes (dicentric assay) is the most appropriate assay to estimate a dose in case of an acute irradiation (18,19) . This assay was also used in a previous examination of the same person years ago (1) . In the present study, a total of 1000 cells from Giemsa stained slides were analysed.…”