Rapid HPGE gamma spectroscopic mapping of transuranic and high energy gamma ray-emitting radionuclides for remediation planning
- CANBERRA Industries, Inc., Greenwood Village, Colorado (United States)
Tank W-1A collected liquid wastes from several high radiation level facilities at the Oak Ridge National Laboratory. Previous environmental samples taken in the general area, particularly at Corehole 8, indicated radiological contamination in adjacent soil. The purpose of this characterization project was to generate three-dimensional maps of the extent of contamination in soil around the tank in order to estimate the volume of transuranic waste (TRU) and low level waste (LLW) for disposal and to plan the remediation operation. A dynamic sampling plan was implemented in which results from each round of sampling determined which subsequent locations would be sampled. This plan maximized the value of data obtained while minimizing project costs and risk. To be effective, dynamic sampling requires that analytical results be available very rapidly. Geo-probe dual-tube soil sampling was used to collect soil cores up to 76 cm long. These cores were immediately brought to two adjacent high purity germanium (HPGe) gamma spectroscopy stations utilizing the In Situ Object Counting System (ISOCS) for quantitative analysis of gamma-emitting radionuclide activity levels. Typically, a 38-cm long core segment was measured for 15 minutes, and the results were reported within 30 minutes, satisfying the requirement for rapid turnaround times. The primary detected radioactive contaminants were {sup 241}Am, {sup 137}Cs, {sup 152}Eu, {sup 154}Eu, and daughters of {sup 232}U, {sup 233}U, and {sup 232}Th. The quantification of {sup 241}Am in the presence of high concentrations of {sup 137}Cs presented some special challenges since Compton effect from the 662 keV {sup 137}Cs gamma rays raised the detection limits in the area of the characteristic 59.5 keV gamma line of {sup 241}Am. This problem was solved using customized counting geometries, lead shielding, and collimators. It was possible to quantify 1.7 x 10{sup 3} Bq/g of {sup 241}Am in the presence of 7.8 x 10{sup 5} Bq/g of {sup 137}Cs. Detection limits for {sup 241}Am were typically less than 370 Bq/g. Transuranic radionuclide detection limits as a function of {sup 137}Cs activity concentration were compared for similar projects using geometries including 150 g sludge samples and 55 gallon waste drums. (authors)
- Research Organization:
- WM Symposia, 1628 E. Southern Avenue, Suite 9 - 332, Tempe, AZ 85282 (United States)
- OSTI ID:
- 21290857
- Report Number(s):
- INIS-US-09-WM-07267; TRN: US10V0182038268
- Resource Relation:
- Conference: WM'07: 2007 Waste Management Symposium - Global Accomplishments in Environmental and Radioactive Waste Management: Education and Opportunity for the Next Generation of Waste Management Professionals, Tucson, AZ (United States), 25 Feb - 1 Mar 2007; Other Information: Country of input: France; 3 refs
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
ALPHA-BEARING WASTES
AMERICIUM 241
CESIUM 137
CONTAMINATION
EUROPIUM 152
EUROPIUM 154
GAMMA RADIATION
HAZARDS
HIGH-PURITY GE DETECTORS
KEV RANGE 100-1000
KEV RANGE 10-100
LIQUID WASTES
LOW-LEVEL RADIOACTIVE WASTES
REMEDIAL ACTION
SENSITIVITY
SOILS
TANKS
THORIUM 232
URANIUM 232
URANIUM 233