干旱区生态环境知识资源中心(Arid): Analysis of Radionuclide Migration Through a 200-m Vadose Zone Following a 16-Year Infiltration Event

Arid

DOI	10.2172/15002146
报告编号	UCRL-ID-146979
来源ID	OSTI_ID: 15002146
	Analysis of Radionuclide Migration Through a 200-m Vadose Zone Following a 16-Year Infiltration Event
	Tompson, A F B; Smith, D K; Hudson, G B
英文摘要	The CAMBRIC nuclear test was conducted beneath Frenchman Flat at the Nevada Test Site on May 14, 1965. The nuclear device was emplaced in heterogeneous alluvium, approximately 70 m beneath the ambient water table, which is itself 220 m beneath the ground surface. Approximately 10 years later, groundwater adjacent to the test was pumped steadily for 16 years to elicit information on radionuclide migration in the saturated zone. The pumping well effluent--containing mostly soluble radionuclides such as tritium, {sup 14}C, {sup 36}Cl, {sup 85}Kr, {sup 129}I, and {sup 106}Ru--was monitored, discharged to an unlined ditch, and allowed to flow towards Frenchman Lake just over one kilometer away. Water discharged into the ditch infiltrated into the ground during flow along the ditch. This created an unexpected and remarkable second experiment in which the migration of the effluent through the 220 meters of unsaturated media, or ''vadose zone'', back to the water table, could be studied. In this paper, the pumping and effluent data are being utilized in conjunction with a series of geologic data, new radionuclide measurements, isotopic age-dating estimates, and vadose zone flow and transport models to better understand the movement of radionuclides between the ditch and the water table. Measurements of radionuclide concentrations in water samples produced from a water table monitoring well 100m away from the ditch indicate rising levels of tritium since 1993. The detection of tritium in the monitoring well occurs approximately 16 years after its initial discharge into the ditch. Modeling and tritium age dating have suggested 3 to 5 years of this 16-year transit time occurred solely in the vadose zone. They also suggest considerable recirculation of the pumping well discharge back into the original pumping well. Surprisingly, no {sup 14}C was observed at the water table, suggesting its preferential retention, possibly due to precipitation or other chemical reaction, during transit to the water table. Overall, the long term nature of the experiment, the variety of chemical measurements and isotopic interpretations, and their incorporation into a unified modeling analysis, have contributed to a unique perspective for interpreting radionuclide migration in the unsaturated zone.
出版年	2002
报告类型	Technical Report
语种	英语
国家	美国
来源学科分类	54 ENVIRONMENTAL SCIENCES ; AGE ESTIMATION ; CHEMICAL REACTIONS ; DETECTION ; METERS ; MONITORING ; NEVADA TEST SITE ; PRECIPITATION ; PUMPING ; RADIOACTIVITY ; RADIOISOTOPES ; RADIONUCLIDE MIGRATION ; RETENTION ; SIMULATION ; TRITIUM ; WATER TABLES
URL	http://www.osti.gov/scitech/servlets/purl/15002146
资源类型	科技报告
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/268323
推荐引用方式 GB/T 7714	Tompson, A F B,Smith, D K,Hudson, G B. Analysis of Radionuclide Migration Through a 200-m Vadose Zone Following a 16-Year Infiltration Event,2002.