Complementary Pu Resuspension Study at Palomares, Spain

Shinn, J

Lawrence Livermore National Laboratory

关键词: Particle Resuspension;    Aerosols;    Inhalation;    Monitoring;    Aerodynamics;   

DOI  :  10.2172/15002129
RP-ID  :  UCRL-ID-150980
RP-ID  :  W-7405-ENG-48
RP-ID  :  15002129

美国|英语

来源: UNT Digital Library

【 摘 要 】

Soil in an area near Palomares, Spain, was contaminated with plutonium as a result of a mid-air collision of U.S. military aircraft in January 1966. The assessment for potential inhalation dose can be found in Iranzo et al., (1987). Long-term monitoring has been used to evaluate remedial actions (Iranzo et al., 1988) and there are many supporting studies of the Pu contamination at Palomares that have been carried out by the Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT) in Madrid. The purpose of this study is to evaluate the resuspension of Pu from the soil in terms of Pu-concentrations in air and resuspension rates in a complementary investigation to those of CIEMAT but in an intensive short-term field effort. This study complements the resuspension studies of CIEMAT at Palomares with additional information, and with confirmation of their previous studies. Observed mass loadings (M) were an average of 70 mg/m{sup 3} with peaks in the daytime of 130 mg/m{sup 3} and low values at night below 30 {micro}g/m{sup 3}. The Pu-activity of aerosols (A) downwind of plot 2-1 was 0.12 Bq/g and the enhancement factor (E{sub f}) had a value of 0.3, which is low but similar to a typical value of 0.7 for other undisturbed sites. This E{sub f} value may increase further away from ground zero. The particle size distribution of the Pu in air measured by cascade impactors was approximately lognormal with a median aerodynamic diameter of 3.7 {micro}m and a geometric standard deviation of 3.5 in the respirable range. This peak midway between 1 ? m and 10 {micro}m in the respirable range is commonly observed. Daily fluctuations in the Pu concentration in air (C) detected by the UHV were lognormally distributed with a geometric standard deviation of 4.9 indicating that the 98th percentile would be 24 times as high as the median. Downwind of plot 2-1 the mean Pu concentration in air, C, was 8.5 {micro}Bq/m{sup 3}. The resuspension factor (Sf) was 2.4 x 10{sup -10} m{sup -1} and agrees very well with the values between 10{sup -10} m{sup -1} and 10{sup -9} m{sup -1} previously reported. We observed a mean Pu/Am ratio of 7.1 with a relative variation of 30%, which compares well with a mean value of 6.5 for nearby plot 2-2. The resuspension rate (R) was in the middle of the range, 10{sup -11} s{sup -1} to 10{sup -12} s{sup -1} as observed in other stable sites, and indicates low potential for Pu redistribution.