A Methodology for Calculating Inhalation Dose to Public Health Personnel Exposed to Material Resuspended from Evacuees Following the Detonation of a Fission Device

Following a nuclear fission event, there likely would be a large number of contaminated persons who would seek assistance at community reception centers to be established outside the affected area. This paper provides a methodology for calculating inhalation doses to public health and other response personnel at such facilities who would be receiving and assisting potentially contaminated persons from whom particles can be resuspended. Three hypothetical facilities were considered: the Base Case is a rather small room with no forced air ventilation. The Preferred Case, which is more realistic, is a mid-sized room with an operating HVAC system with air being recirculated through a filter. The Gymnasium Case has only fresh air intake. Initial bounding calculations for the Base Case indicated the need for pre-screening of arrivals to avoid unacceptable doses to staff. The screening criterion selected was 1.67 × 10 6 Bq m -2 . Calculations are presented for radionuclide concentrations in air, dose to staff from inhalation, and how exposures and the resulting doses can be altered by air-turnover rates and the use of filters with varying efficiency. Doses are presented for various arrival times and for both plutonium- and uranium-fueled detonations. The highest calculated dose via inhalation with no respiratory protection was 0.23 mSv for the Base Case. The more important radionuclides contributing to dose with exposure starting at day D + 1 were 239 Np and 133 I. At day D + 30, 131 I and 140 Ba were the more important dosimetrically. The variable creating the highest uncertainty was the slough-off factor for resuspension of contamination from people arriving at the reception center.