Hydrologic Resources Management Program and Underground Test Area Project FY 2001-2002 Progress Report
This report contains highlights of FY 2001 and 2002 technical studies conducted by the Analytical and Nuclear Chemistry Division (ANCD) at Lawrence Livermore National Laboratory (LLNL) in support of the Hydrologic Resources Management Program (HRMP) and the Underground Test Area (UGTA) Project. These programs are administered by the U.S. Department of Energy, National Nuclear Security Administration, Nevada Site Office (NNSA/NSO) through the Defense Programs and Environmental Restoration Divisions, respectively. HRMP-sponsored work emphasizes the Defense Programs goal of responsible management of natural resources at the NTS, while UGTA-funded work focuses on defining the extent of radionuclide contamination in NTS groundwater resulting from underground nuclear testing. The report is organized on a topical basis, and contains eight chapters that reflect the range of technical work performed by LLNL-ANCD in support of HRMP and UGTA. Chapter 1 describes recent hot well sampling efforts at the NTS, and presents the results of chemical and isotopic analyses of groundwater samples from six near-field wells. These include the Cambric (UE-5n), Bilby (U-3cn PS No.2), Bourbon (UE-7nS), Nash (UE-2ce), Tybo/Benham (ER-20-5 No.3), and Almendro (U-19v PS No.1ds) sites. The data generated by the hot well program is vital to the development and validation of contaminant transport models at the NTS. Chapter 2 discusses the results of xenon isotope measurements of groundwater samples from the six near-field wells described in Chapter 1. This work demonstrates that fission xenon is present in the water at levels that are readily measurable and highlights the significant differences in xenon concentrations and isotopic abundances at different sites. These differences provide insight into the early cooling history of nuclear test cavities, and may assist in predicting the distribution of the source term in the near-field environment. Chapter 3 is an investigation of the distribution and abundance of actinides in a nuclear test cavity and chimney. This work demonstrates that early-time processes can widely disperse actinides at low concentrations outside the melt glass, implying that melt glass dissolution may not be the sole mechanism for the release of actinides to groundwater. The study also provides evidence for the isotopic fractionation of plutonium under the extreme conditions accompanying nuclear explosions. In Chapter 4, X-ray absorption spectroscopy measurements were used to determine the redox state of Fe and U in nuclear melt glass samples from the NTS. Both elements were found to occur in mixed valence states (Fe{sup 2+}/Fe{sup 3+} and U{sup 5+}/U{sup 6+}) in all samples. Comparison of the Fe and U redox states with published redox studies of synthetic glasses suggests that plutonium is predominantly in the Pu{sup 4+} oxidation state in the melt glasses. In Chapter 5, alpha autoradiography is used in a NTS field study to investigate the spatial distribution and transport of actinides in soils, and to help identify the size distribution and morphology of the actinide particles. It was found that {alpha}-emitting radionuclides have moved to at least 39 cm depth in the soil profile, far deeper than expected. The methodology that was developed could easily be applied to other field locations where actinides are dispersed in the soil zone. Chapter 6 summarizes the development of a method for measuring environmental levels of {sup 241}Am on the multi-collector inductively coupled plasma mass spectrometer. The method detection limit of 0.017 pCi/L is about two times lower than the best analyses possible by alpha spectrometry. Chapter 7 describes a chlorine-36 study of vertical groundwater transport processes in Frenchman Flat. Mass balance calculations developed from a {sup 36}Cl mixing model at well ER-5-3 No.2 are used to estimate vertical transport fluxes and average vertical flow velocities through the thick volcanic section underlying the basin. The study also documents the variations in {sup 36}Cl/Cl ratios within the three principal hydrostratigraphic units in Frenchman Flat. Chapter 8 discusses an ongoing stable isotope investigation of precipitation and recharge processes in central Nevada. Precipitation, spring water, and shallow infiltration samples have been collected at four locations on a biannual basis since 1999. The results show that winter precipitation accounts for >90% of the recharge at these sites. Lysimeter data suggest that most of the evaporation occurring during recharge is due to water vapor loss through the soil zone during periods of slow infiltration. In addition to the topical investigations described above, LLNL-ANCD contributed to several other major collaborative technical products during FY 2001 and 2002.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 15007318
- Report Number(s):
- UCRL-ID-154357; TRN: US0401637
- Resource Relation:
- Other Information: PBD: 15 Aug 2003
- Country of Publication:
- United States
- Language:
- English
Similar Records
Hydrologic Resources Management Program and Underground Test Area Project FY 2006 Progress Report
Hydrologic Resources Management Program and Underground Test Area Project FY 2000 Progress Report
Related Subjects
45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
54 ENVIRONMENTAL SCIENCES
58 GEOSCIENCES
ABSORPTION SPECTROSCOPY
ALPHA PARTICLES
ALPHA SPECTROSCOPY
CHLORINE 36
MANAGEMENT
MASS BALANCE
MASS SPECTROMETERS
NUCLEAR CHEMISTRY
NUCLEAR EXPLOSIONS
PROGRESS REPORT
SENSITIVITY
SOURCE TERMS
SPATIAL DISTRIBUTION
STABLE ISOTOPES
WATER VAPOR
XENON ISOTOPES