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  • Author or Editor: W. Andrews x
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Summary  

In 1951, 6.7 liter of an aqueous solution of actinides, fission and daughter products leaked from an underground storage tank into prairie soil. In 2001, soil samples were collected from the site to determine the degree and extent of the contamination. This paper reports on the continuation of complementary analytical techniques used to determine the concentrations of the contaminants in the soil samples, including gamma-ray spectroscopy, neutron activation analysis (NAA) and liquid scintillation counting (LSC). Gamma-ray spectroscopy was able to identify and quantify the presence of 137Cs, while the activities of the actinides and remaining fission and daughter products were too low to be measured. Concentrations of 137Cs as low as 0.15 Bq/g and as high as 341 Bq/g were measured. NAA was successful in detecting 238U. Only preliminary LSC analysis has been conducted, resulting in gross beta-counts for the soil samples. Finally, correlations were developed between borehole gamma logging values and corresponding concentrations of 137Cs determined by gamma-spectroscopy and gross beta-counts from LSC analysis.

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Abstract  

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.

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Abstract  

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.

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Abstract  

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.

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Abstract  

A computer program entitled SCAAP (Set-up, Calibration, Acquisition and Analysis Program) has been designed to make gamma-ray spectroscopy easily useable by staff in laboratories at the Slowpoke-2 Facility at RMC and in support of the Canadian Forces Nuclear Emergency Response Teams (NERTs). The former group utilises gamma-ray spectroscopy for neutron activation analysis (NAA), while the latter may need to have inhalation dose rates calculated. The intent of this program, written using Microsoft Visual Basic, is to provide a simplified interface between the operator and the spectroscopy equipment and to provide the calculations necessary to produce results quickly. There are five sections (Setup, Calibrate, Acquire, Analyse and NAA) of which the first four are linked. In these sections, a checklist of procedures is presented and automated for the user to set up and calibrate the equipment and then to analyse spectra to provide various dose rates. In the unlinked section, NAA, gamma-ray spectra are analysed to provide elemental concentrations in samples.

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Abstract  

A radioactive aerosol and vapor dispersion model, RADiM, has been developed to predict the distribution of acquired doses from radionuclides escaping into the atmosphere following a marine reactor accident. Designed as a decision aid for emergency response teams, RADiM is based on a Gaussian plume model, which considers decay and transmutation, as well as meteorological and terrain effects. An initially estimated source term can be adjusted for strength and composition, based on subsequent field survey measurements and gamma-spectroscopy. RADiM was validated using field release data and was compared to predictions from established codes. Possible accident scenarios were also examined.

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Summary  

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.

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Abstract  

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.

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