Colin G. Sanderson

Factors that cause seasonal variations in Beryllium-7 concentrations in surface air

Seasonal variations in the concentration of 7Be in surface air appear to show the effects of at least four factors. The influences of variations both in the rate of exchange between the stratosphere and the troposphere and in the rate of vertical mixing within the troposphere are evident in concentrations at most sites in middle latitudes. Concentrations at high latitude sampling sites show the effect of seasonal variations in the transport of air masses from middle latitudes into the high latitudes. Several sites located in regions where there are strong seasonal variations in the rainfall rate show an inverse correlation between the 7Be concentrations and the rainfall rates, indicating the importance of washout of the atmospheric aerosol that carries the 7Be.

Fallout in the New York metropolitan area following the chernobyl accident

In the metropolitan New York area, maximum concentrations in air of radioactive aerosol and gaseous debris from the Chernobyl accident of April 1986 were much lower than those measured in Europe. The observed maxima were: for gaseous 131I, 23mBq m−3; for aerosol samples, 20mBq m−3 of 131I and 9·mBq m−3 of 137Cs. The data suggest that little gas-to-particle transformation of iodine occurred during transport of the radioactive cloud from the Ukraine to New York. The ratios of 103Ru and other refractories to 137Cs were low in the first debris sampled, debris which probably was emitted from Chernobyl in late April during the early stages of the accident. In subsequent samples these ratios were higher, presumably because debris from the later, hotter stages of the fire had reached our sampling sites. A significant fraction (25–40%) of the deposition of 131I and 137Cs into our samplers and on grass was by dry deposition. The total deposition of Chernobyl 137Cs in the area was <1% of that already present in the soil from fallout from past nuclear weapon tests. The highest concentration of 131I measured in fresh milk was about 1.5 B1 liter−1, <0.1% of the US action level. The dose to the thyroid of a six-month-old infant who had fresh milk as a sole food source would be about 70 μGy (7 mrad).

A bone ash standard for90Sr,210Pb,210Po, uranium and the actinides

A bone ash standard for a number of radionuclides is required as a quality control sample in dosimetry studies with bone as the critical organ. The procedures that were used to prepare a candidate bone ash standard are given with some initial encouraging measurements that the candidate sample will meet the requirements of NIST standard reference manual.

Environmental gamma-ray spectroscopy at remote sites with satellite data transmission

Abstract We describe in this paper remote atmospheric measurement systems that are used in the Environmental Measurements Laboratorys (EML) Remote Atmospheric Measurements Program to measure gamma-ray emitting radionuclides that have been collected by drawing air through highly efficient filters. The gamma-ray spectrum is transmitted to polar orbiting ARGOS satellites, transferred to a ground station, and recovered via a telephone link by EMLs computer. The recovered NaI gamma-ray spectrum is automatically resolved using a linear least squares program. Over 2000 NaI spectra have been received from these remote sites. These spectra provide information on isotopes of current interest and serve as a data base for the future studies of other radionuclides which may become of interest.

A reevaluation of commercial IBM PC software for the analysis of low-level environmental gamma-ray spectra

Abstract In 1988, a comparative evaluation of seven commercially available software packages for the analysis of low-level environmental gamma-ray spectra was performed. At that time it was determined that many of the packages did not contain all the features that were necessary for the accurate analysis of complex, low-level environmental samples. The evaluation concentrated on peak detection, noise and phantom-peak rejection, resolution of peak doublets, and nuclide identification. A new evaluation was conducted on updated versions of four of the previously evaluated programs and two additional programs from Canada and Germany. The evaluation involved the analysis of synthetic and actual spectral data, including an air filter containing debris from the Chernobyl accident. System requirements, accurate nuclide quantification and ease of operation are also reported.

Assessing the quality of environmental monitoring programs

Abstract The Environmental Measurements Laboratory is conducting a program to assess the quality of environmental data being reported to the U.S. Department of Energy by 35 of its contractors. This paper presents a description of this assessment program. Semiannually, the Environmental Measurements Laboratory sends samples of soil, water, vegetation, tissue, and filter papers to the participants for analysis. The results of the analyses performed during the 8 years this program has been in operation have been satisfactory.

Spiked natural matrix materials as quality assessment samples

The Environmental Measurements Laboratory has conducted the Quality Assessment Program (QAP) since 1976 to evaluate the quality of the environmental radioactivity data, which is reported to the Department of Energy by as many as 42 commercial contractors involved in nuclear work. In this program, matrix materials of known radionuclide concentrations are distributed routinely to the contractors and the reported results are compared. The five matrices used are: soil, vegetation, animal tissue, water and filter paper. Environmental soil, vegetation and animal tissue are used, but the water and filter paper samples are prepared by spiking with known amounts of standard solutions traceable to the National Bureau of Standards. A summary of results is given to illstrate the successful operation of the program. Because of the difficulty and high cost of collecting large samples of natural matrix material and to increase the versatility of QAP, an attempt was recently made to prepare the soil, vegetation and animal tissue samples with spiked solutions. A description of the preparation of these reference samples and the results of analyses are presented along with a discussion of the pitfalls and advantages of this approach.

An Intelligent Radiation Detector System For Remote Monitoring

A unique real‐time gamma radiation detector and spectroscopic analyzer, specifically designed for a “Homeland Security Radiological Network”, has been developed by the Environmental Measurements Laboratory (EML). The Intelligent Radiation Detector’s (IRD) sensitivity and rapid sampling cycle assure up‐to‐the minute radiological data, which will indicate fast changes in atmospheric radioactivity. In addition, an immediate alert will occur within seconds to signal rapid changes in activity or levels elevated beyond a preset. This feature is particularly valuable to detect radioactivity from moving vehicles. The IRD also supplies spectral data, which allows the associated network computer to identify the specific radionuclides detected and to distinguish between natural and manmade radioactivity. To minimize cost and maximize rapid availability, the IRD uses readily available “off the shelf” components combined with an inexpensive, unique detector housing made of PVC plastic pipe. Reliability with no require...