Chemical warfare agents have been stockpiled for almost a decade and their destruction has become an environmental issue that
will continue to require attention for many years. There are hundreds of thousands of tonnes yet to be destroyed, and the
current chemical or incineration techniques are not without problems. While many researchers are seeking better chemical techniques,
we decided to try ionizing radiation to destroy sulphur mustard with the goal of producing non-toxic products. We irradiated
a variety of sulphur mustard samples by both a mixed field source (β, γ and neutrons) and a pure gamma source. The mixed field
irradiation of wet sulphur mustard for long irradiation times was the most successful at destroying the chemical agent.
Soil samples were collected at the site of a 1951 leak from an underground storage tank of 6.7 liter of an aqueous solution
of irradiated uranium. Laboratory simulations were conducted using irradiated and non-irradiated natural uranium metal, dissolved
in acidic aqueous solutions and added to soil columns. Contaminant transport experiments were conducted for a period of 12
to 14 months, followed by sample analysis employing gamma-spectroscopy, neutron activation analysis and liquid scintillation
counting. The concentration distributions of U, Cs and Sr found from the experiments were used to derive diffusion coefficients.
The measured diffusion coefficients from the field samples were: for 137Cs, 3.0E-04 cm2·s−1; for 238U, 1.8E-09 cm2·s−1; and for 90Sr, 2.6E-09 cm2·s−1. Corresponding values for the laboratory simulations were 5E-06, 3E-05 and 1.9E-05 cm2·s−1, respectively.
Authors:D. Sims, W. Andrews, X. Wang, and K. Creber
In 1951, unsaturated prairie soil was contaminated with fission products and actinides. Fifty years later, in 2001, soil samples
were collected from the contaminated site. This paper describes the techniques used to analyze these samples, including gamma-spectroscopy
(GS) for 137Cs, neutron activation analysis (NAA/GS) for 238U, liquid scintillation counting (LSC) for 90Sr and inductively coupled plasma mass spectroscopy (ICP-MS) for 238U and 113mCd. As expected, ICP-MS was found to have the lowest detection level, while the techniques were ranked in order of increasing
uncertainty as GS, NAA/GS, ICP-MS and LSC.
Authors:D. J. Sims, W. S. Andrews, K. A. M. Creber, and X. Wang
In 1951, 6.7 liters of an aqueous acidic solution of irradiated uranium (360 GBq) leaked from a buried storage tank into unsaturated prairie soil, where it has remained, undisturbed. In October 2001, sonic drilling was conducted to recover core samples around and below the tank location. This paper describes the measurements and investigative approaches being pursued to determine the transport properties of the various fission and daughter products and actinides. Separate effects laboratory experiments are also being conducted involving both inert and radioactive samples in similar soil, to examine the effects on transport properties (diffusion and sorption) of temperature, recharge and discharge rates, concentration and soil porosity. Finally, transport modeling approaches are discussed.
Authors:W. Andrews, E. Waller, P. Brousseau, G. Roy, X. Cao, K. Creber, and L. Erhardt
During the past decade, interest has increased in qualifying and quantifying the threat posed to the public by the illegal
use of radionuclides. In order to take investigations beyond the laboratory bench into more realistic scenarios, environmental
and safety considerations dictate that these studies be performed on stable and benign surrogates. This paper discusses some
of these studies, specifically the use of cerium dioxide for actinide ceramics and calcium and natural strontium ceramics
for those based on 90Sr.