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Neutron and gamma (density) logging in welded tuff

Description: This Technical Implementation Procedure (TIP) describes the field operation, and the management of data records pertaining to neutron logging and density logging in welded tuff. This procedure applies to all borehole surveys performed in support of Engineered Barrier System Field Tests (EBSFI� ), including the Earge Block Tests (LBT) and Initial Engineered Barrier System Field Tests (IEBSFT) - WBS 1.2.3.12.4. The purpose of this TIP is to provide guidelines so that other equally trained and qualified personnel can understand how the work is performed or how to repeat the work if needed. The work will be documented by the use of Scientific Notebooks (SNs) as discussed in 033-YMP-QP 3.4. The TIP will provide a set of guidelines which the scientists will take into account in conducting the mea- surements. The use of this TIP does not imply that this is repetitive work that does not require profes- sional judgment.
Date: September 12, 1998
Creator: Lin, W.
Partner: UNT Libraries Government Documents Department

Baseline neutron logging measurements in the drift scale test

Description: The Drift Scale Test (DST) is one of the thermal tests being conducted in the Exploratory Studies Facility (ESF). One of the objectives of the DST is to study the coupled thermal-mechanical- hydrological-chemical (TMHC) processes in the ESF at the repository horizon of the potential high-level nuclear waste repository in Yucca Mountain, Nevada. The objectives, the test design, and the test layouts of the DST are included in the test design report by CRWMS M&O Contractor LLNL. The configuration of the DST includes a declining Observation Drift driven mostly east and downward from main tunnel in the ESF, at about 2.827 km from the North portal. The downward slope of the Observation Drift (11.5 to 14.0 percent) ensures a minimum 10 m of middle nonlithophysal Topopah Spring Tuff as the overburden for the DST. The length of the Observation Drift is about 136 m. At the elevation of the DST crown (nominally 10 m below the upper extent of the middle nonlithophysal Topopah Spring Tuff) the Connecting Drift breaks out to the north from the Observation Drift, 136 m from the main tunnel of the ESF. The Connecting Drift extends approximately 40 m to the north from the Observation Drift. A Heater Drift breaks out westward from the Connecting Drift at about 30 m from the Observation Drift. The Heater Drift consists of an 11 m long entry, which includes a plate- loading niche, and a 47 m long heated drift. The nominal diameter of the drifts is 5 m. The detail configuration of the DST, including diagrams showing the drift and borehole layout, is included in the test design report by CRWMS M&O Contractor LLNL. Thermal neutron logging is a method used to determine moisture content in rocks and soils and will be used to monitor moisture content in ...
Date: January 1, 1998
Creator: Lin, W.; Carlson, R. & Neubaurer, D.
Partner: UNT Libraries Government Documents Department

A new intense neutron generator and high-resolution detector for well logging applications

Description: Advances in both ion source and gamma-ray detector technology at LBNL are being used to develop a new high-sensitivity neutron logging instrument. Up to 37 mA of current per 10-20 {mu}s pulse, 80-95% D{sup +}, has been produced by a 2 inch diameter pulsed multicusp ion source. A D-T neutron flux of 10{sup 9}-10{sup 10} n/s is projected from this data. CdZnTe is being developed as a possible gamma-ray detector because of its potential for good energy resolution and efficiency, and ability to operate at room temperature. 3-D time-dependent Monte Carlo calculations show the utility of this system for locating contaminants, especially chlorine-containing solvents, at remediation sites.
Date: October 1, 1996
Creator: Celata, C.M.; Amman, M. & Donahue, R.
Partner: UNT Libraries Government Documents Department

RCRA Post-Closure Monitoring and Inspection Report for CAU 91: Area 3 U-3fi Waste Unit, Nevada Test Site, Nevada, for the Period October 1999-October 2000

Description: This annual Neutron Soil Moisture Monitoring report provides an analysis and summary for site inspections, meteorological information, and neutron soil moisture monitoring data obtained at the U-3fi Resource Conservation and Recovery Act Unit, located in Area 3 of the Nevada Test Site, Nye County, Nevada, during the October 1999 to October 2000 period. Inspections of the U-3fi Resource Conservation and Recovery Act Unit are conducted to determine and document the physical condition of the concrete pad, facilities, and any unusual conditions that could impact the proper operation of the waste unit closure. The objective of the neutron-logging program is to monitor the soil moisture conditions along the 128-meter (m) (420-feet [ft]) ER3-3 monitoring well and detect changes that maybe indicative of moisture movement in the regulated interval extending between 73 to 82 m (240 to 270 ft) or to detect changes that maybe indicative of subsidence within the disposal unit itself. Physical inspections of the closure were completed in March and September 2000 and indicated that the site is in good condition with no significant findings noted. The directional survey which is required to be completed every five years was run in the ER3-3 casing to determine if subsidence was occurring in the U-3fi emplacement borehole. Small changes were noted which are attributed to initial settling of the sand pack stemming. No evidence of subsidence within the emplacement borehole was observed. The subsidence survey for the October 1999 to October 2000 monitoring period indicated an increase in elevation of 0.244 centimeters (cm) (0.008 ft) compared to the previous year, July 1999. All changes in subsidence survey data taken to date are so small as to be at the survey instrument resolution level and it is not clear if they represent subsidence or measurement error. There is no clear evidence for ...
Date: February 1, 2001
Creator: Emer, D. F.
Partner: UNT Libraries Government Documents Department

RCRA Post Closure Monitoring and Inspection Report for CAU 91: Area 3 U-3fi Waste Unit, Nevada Test Site for the Period October 1996-1997

Description: This annual Neutron Soil Moisture Monitoring report provides an analysis and summary for site inspections, meteorological information, and neutron soil moisture monitoring data obtained at the U-3fi Resource Conservation and Recovery Act (RCRA) Unit, located in Area 3 of the Nevada Site (NTS), Nye County, Nevada, during the October 1996-October 1997 period. Inspections of the U-3fi RCRA Unit are conducted to determine and document the physical condition of the concrete pad, facilities, and any unusual conditions that could impact the proper operation of the waste unit closure. The objective of the neutron logging is to monitor the soil moisture conditions along the 128 meter (420 feet) ER3-3 monitoring well and detect changes that may be indicative of moisture movement in the regulated interval extending between 73 m to 82 m (240 to 270 ft).
Date: January 1, 1998
Creator: Emer, Dudley
Partner: UNT Libraries Government Documents Department

Annual Report RCRA Post-Closure Monitoring and Inspections for Corrective Action Unit 112: Area 23 Hazardous Waste Trenches, Nevada Test Site, Nevada

Description: This annual Neutron Soil Moisture Monitoring report provides an analysis and summary for site inspections, meteorological information, and neutron soil moisture data obtained at the Area 23 Hazardous Waste Trenches Resource Conservation and Recovery Act (RCRA) unit, located in Area 23 of the Nevada Test Site, Nye County, Nevada during the October 1997 - October 1998 period. Inspections of the Area 23 Hazardous Waste Trenches RCRA unit are conducted to determine and document the physical condition of the covers, facilities, and any unusual conditions that could impact the proper operation of the waste unit closure. Physical inspections of the closure were completed quarterly and indicated that the site is in good condition with no significant findings noted. An annual subsidence survey of the elevation markers was conducted in July 1998. There has been no subsidence at any of the markers since monitoring began six years ago. The objective of the neutron logging program is to monitor the soil moisture conditions along 30 neutron access tubes and detect changes that may be indicative of moisture movement at a point located directly beneath each trench. All monitored access tubes are within the compliance criteria of less than 5 percent residual volumetric moisture content at the compliance point directly beneath each respective trench. Soil conditions remain dry and stable underneath the trenches.
Date: January 1, 1999
Creator: Emer, Dudley F.
Partner: UNT Libraries Government Documents Department

A suction lysimeter and a geophysical access port

Description: A sampling apparatus is described for monitoring vadose zones, geologic media or buried waste in sediment and more particularly to such an apparatus which is operable as an access port for geophysical logging and collecting fluid samples to permit analysis of such fluid samples for the presence of toxic substances, having a pipe-like, stainless steel, longitudinally extending, access tube with two ends, where the first end extends above the surface of the sediment and has a removable air tight seal. The subject invention further has a backing in fluid communication with the access tube and a fluid permeable plate contiguous with the backing, wherein the fluid permeable plate is made up of porous stainless steel. A reservoir is integrated into the second closed end of the access tube for containing the collected fluid. A vacuum pump, having a vacuum gauge/transducer attached thereto, is connected to the removable air tight seal for applying a vacuum to the access tube, such that gas and fluid samples may be drawn through the fluid permeable plate. A fluid sample connector coupled to the removable air tight seal, in addition to the vacuum pump with vacuum gauge/transducer, for withdrawing a fluid sample from the access tube.
Date: December 31, 1995
Creator: Hubbell, J.M. & Sisson, J.B.
Partner: UNT Libraries Government Documents Department

First-quarter report of neutron logging during the heating phase of the drift-scale test

Description: The Drift-Scale Test (DST) is one of the thermal tests being conducted in the Exploratory Studies Facility (ESF). One of the purposes of the DST is to study, at the ESF, the coupled thermal- mechanical- hydrologic-chemical (TMHC) processes at the repository horizon of the potential high-level nuclear waste repository at Yucca Mountain, Nevada. The objectives, the test design, and the test layouts of the DST are included in the test design report by the Civilian Radioactive Waste Management System Management and Operation (CRWMS M&O) contractors. The configuration of the DST includes a declining observation drift driven mostly east and downward from main tunnel in the ESF at approximately 2.827 km from the north portal. The downward slope of the observation drift (11.5% to 14.0%) ensures a minimum of 10 m of middle nonlithophysal Topopah Spring tuff as the overburden for the DST. The length of the observation drift is approximately 136 m. At the elevation of the DST crown (nominally 10 m below the upper extent of the middle nonlithophysal Topopah Spring tuff), the connecting drift breaks out to the north from the observation drift 136 m from the main tunnel of the ESF. The connecting drift extends approximately 40 m to the north from the observation drift. A heater drift breaks out westward from the connecting drift at approximately 30 m from the observation drift. The heater drift consists of an 11-m-long entry, which includes a plate-loading niche, and a 47-m-long heated drift. The nominal diameter of the drifts is 5 m. The detail configuration of the DST, including diagrams showing the drift and borehole layout, is included in the test design report by CRWMS M&O contractors.
Date: April 1, 1998
Creator: Lin, W., LLNL
Partner: UNT Libraries Government Documents Department

Annual Report RCRA Post-Closure Monitoring and Inspections for CAU 112: Area 23 Hazardous Waste Trenches, Nevada Test Site, Nevada, for the Period October 1999-October 2000

Description: This annual Neutron Soil Moisture Monitoring report provides an analysis and summary for site inspections, meteorological information, and neutron soil moisture monitoring data obtained at the Area 23 Hazardous Waste Trenches Resource Conservation and Recovery Act (RCRA) unit, located in Area 23 of the Nevada Test Site, Nye County, Nevada, during the October 1999-October 2000 period. Inspections of the Area 23 Hazardous Waste Trenches RCRA unit are conducted to determine and document the physical condition of the covers, facilities, and any unusual conditions that could impact the proper operation of the waste unit closure. Physical inspections of the closure were completed quarterly and indicated that the site is in good condition with no significant findings noted. An annual subsidence survey of the elevation markers was conducted in August 2000. There has been no subsidence at any of the markers since monitoring began seven years ago. The objective of the neutron logging program is to monitor the soil moisture conditions along 30 neutron access tubes and detect changes that maybe indicative of moisture movement at a point located directly beneath each trench. Precipitation for the period October 1999 through October 2000 was 10.44 centimeters (cm) (4.11 inches [in.]) (U.S. National Weather Service, 2000). The prior year annual rainfall (January 1999 through December 1999) was 10.13cm (3.99 in.). The highest 30-day cumulative rainfall occurred on March 8, 2000, with a total of 6.63 cm (2.61 in.). The heaviest daily precipitation occurred on February 23,2000, with a total of 1.70 cm (0.67 in.) falling in that 24-hour period. The recorded average annual rainfall for this site, from 1972 to January 1999, is 15.06 cm (5.93 in.). All monitored access tubes are within the compliance criteria of less than 5 percent residual volumetric moisture content at the compliance point directly beneath each respective trench. ...
Date: March 1, 2001
Creator: Emer, D. F.
Partner: UNT Libraries Government Documents Department

Monitoring and data analysis for the Vadose Zone Monitoring System (VZMS), McClellan AFB. Quarterly status report, August 15, 1997--November 15, 1997

Description: This report contains information on field and laboratory work performed between August 15th and November 15th at site S-7 in IC 34, at McClellan AFB. At this location, a Vadose Zone Monitoring System (VZMS) (LBNL, 1996) is currently being used to collect subsurface data including hydraulic potential, soil gas pressure, moisture content, water chemistry, gas chemistry, and temperature.
Date: December 5, 1997
Creator: Zawislanski, P.T.; Mountford, H.S.; Dahlquist, R.; Rodriguez, S.J. & Salve, R.
Partner: UNT Libraries Government Documents Department

An efficient simulation model for nuclear geophysical measurements

Description: Nuclear measurements that provide data related to geophysical parameters have been used for many years in well-logging, surface surveys, and laboratory core studies. The measurement process can be considered in two parts: (1) the transport of nuclear radiation from source to detector; and (2) the interaction of the transported radiation with the detector. For certain measurement problems, the radiation transport of step is not strongly affected by the presence of the detector in step 2. For such problems a simulation approach that decouples radiation transport from detection suggests itself. Many nuclear geophysical measurements can be modeled in this way. This method was first utilized to simulate aerial radiometric surveys and borehole logs for potassium, uranium, and thorium. A one-dimensional deterministic technique was used to model the gamma-ray transport from ground sources and the stoichastic Monte Carlo technique to model the detector response. The results of the two separate simulations are convolved to model a given source and detector combination. The method is an efficient way to model combinations of various radiation transport geometries with differing detector types and sizes. This simulation approach has been extended in the present work to include two-dimensional geometries. The two-dimensional model applies exactly to centralized well-logging tools and in an approximate form for many eccentered measurements. The model is now being used to simulate neutron porosity and gamma-gamma density measurements.
Date: January 1, 1987
Creator: Wilson, R.D.; Cook, T.K. & Dean, S.H.
Partner: UNT Libraries Government Documents Department

Annual Report RCRA Post-Closure Monitoring and Inspections for CAU 112: Area 23 Hazardous Waste Trenches, Nevada Test Site, Nevada, for the period October 2000-July 2001

Description: This annual Neutron Soil Moisture Monitoring report provides an analysis and summary for site inspections, meteorological information, and neutron soil moisture monitoring data obtained at the Area 23 Hazardous Waste Trenches Resource Conservation and Recovery Act (RCRA) unit, located in Area 23 of the Nevada Test Site, Nye County, Nevada, during the October 2000--July 2001 monitoring period. Inspections of the Area 23 Hazardous Waste Trenches RCRA unit are conducted to determine and document the physical condition of the covers, facilities, and any unusual conditions that could impact the proper operation of the waste unit closure. Physical inspections of the closure were completed quarterly and indicated that the site is in good condition with no significant findings noted. An annual subsidence survey of the elevation markers was conducted in July 2001. There has been no subsidence at any of the markers since monitoring began eight years ago. Precipitation for the period October 2000 through July 2001 was 9.42 centimeters (cm) (3.71 inches [in]) (U.S. National Weather Service, 2001). The prior year annual rainfall (January 2000 through December 2000) was 10.44 cm (4.1 1 in.). The recorded average annual rainfall for this site from 1972 to January 2000 is 14.91 cm (5.87 in.). The objective of the neutron logging program is to monitor the soil moisture conditions along 30 neutron access tubes and detect changes that may be indicative of moisture movement at a point located directly beneath each trench. All monitored access tubes are within the compliance criteria of less than 5 percent residual volumetric moisture content at the compliance point directly beneath each respective trench. Soil conditions remain dry and stable underneath the trenches.
Date: January 1, 2002
Creator: Tobiason, D. S.
Partner: UNT Libraries Government Documents Department

Shallow infiltration processes at Yucca Mountain, Nevada - neutron logging data 1984-93

Description: To determine site suitability of Yucca Mountain, Nevada, as a potential high-level radioactive waste repository, a study was devised to characterize net infiltration. This study involves a detailed data set produced from 99 neutron boreholes that consisted of volumetric water-content readings with depth from 1984 through 1993 at Yucca Mountain. Boreholes were drilled with minimal disturbance to the surrounding soil or rock in order to best represent field conditions. Boreholes were located in topographic positions representing infiltration zones identified as ridge-tops, sideslopes, terraces, and active channels. Through careful field calibration, neutron moisture logs, collected on a monthly basis and representing most of the areal locations at Yucca Mountain, illustrated that the depth of penetration of seasonal moisture, important for escaping loss to evapotranspiration, was influenced by several factors. It was increased (1) by thin soil cover, especially in locations where thin soil is underlain by fractured bedrock; (2) on ridgetops; and (3) during the winter when evapotranspiration is low and runoff is less frequent. This data set helps to provide a seasonal and areal distribution of changes in volumetric water content with which to assess hydrologic processes contributing to net infiltration.
Date: November 1, 1995
Creator: Flint, L. E. & Flint, A. L.
Partner: UNT Libraries Government Documents Department

Assessment of vadose zone radionuclide contamination around Single Shell Tank 241-C-103

Description: Five drywells surrounding single shell tank 241-C-103 were logged with the high-purity germanium logging system to investigate possible leakage of radioactive contamination from the tank. The investigation included integration of the drywell survey results with several other data sources. There is no conclusive evidence showing indications that the 241-C-103 tank has leaked
Date: December 1, 1995
Creator: Kos, S.E.
Partner: UNT Libraries Government Documents Department

Moisture monitoring in large diameter boreholes

Description: The results of both laboratory and field experiments indicate that the neutron moisture gauge traditionally used in soil physics experiments can be extended for use in large diameter (up to 15 cm) steel-cased boreholes with excellent results. This application will permit existing saturated zone monitoring wells to be used for unsaturated zone monitoring of recharge, redistribution and leak detection from waste disposal facilities. Its applicability to large diameter cased wells also gives the soil physicist and ground-water hydrologist and new set of monitoring points in the unsaturated zone to study recharge and aquifer properties. 6 refs., 6 figs., 2 tabs.
Date: November 19, 1985
Creator: Tyler, S.
Partner: UNT Libraries Government Documents Department

Monte Carlo simulations of neutron well-logging in granite and sand to detect water and trichloroethane (TCA)

Description: The Monte Carlo code MCNP is used in simulations of neutron well logging in granite to detect water and TCA (C{sub 2}H{sub 3}Cl{sub 3}), a common ground contaminant, in fractures of 1 cm and 1 mm thickness at various distances and orientations. Also simulated is neutron well logging in wet sand to detect TCA and lead (Pb) at various uniform concentrations. The {sup 3}H(d,n) (DT) and{sup 2}H(d,n) (DD) neutron producing reactions are used in the simulations to assess the relative performance of each. Simulations are also performed to determine the efficiency of several detector materials such as CdZnTe, Ge and NaI as a function of photon energy. Results indicate that, by examining the signal from the 6.11 MeV gamma from the thermal neutron capture of Cl in TCA, trace amounts (few ppm) are detectable in saline free media. Water and TCA filled fractures are also detectable. These results are summarized in Tables 7--21. Motivation for this work is based on the need for detection of trace environmental pollutants as well as possible fracture characterization of geologic media.
Date: January 1, 1998
Creator: Hua, D.D.; Donahue, R.J.; Celata, C.M. & Greenspan, E.
Partner: UNT Libraries Government Documents Department

Synopsis of moisture monitoring by neutron probe in the unsaturated zone at Area G

Description: Moisture profiles from neutron probe data provide valuable information in site characterization and to supplement ground water monitoring efforts. The neutron probe precision error (reproducibility) is found to be about 0.2 vol% under in situ field conditions where the slope in moisture content with depth is varying slowly. This error is about 2 times larger near moisture spikes (e.g., at the vapor phase notch), due to the sensitivity of the probe response to vertical position errors on the order of 0.5 inches. Calibrations were performed to correct the downhole probe response to the volumetric moisture content determined on core samples. Calibration is sensitive to borehole diameter and casing type, requiring 3 separate calibration relations for the boreholes surveyed here. Power law fits were used for calibration in this study to assure moisture content results greater than zero. Findings in the boreholes reported here confirm the broad features seen previously in moisture profiles at Area G, a near-surface region with large moisture variability, a very dry region at greater depths, and a moisture spike at the vapor phase notch (VPN). This feature is located near the interface between the vitrified and vitrified stratigraphic units and near the base of the mesa. This report describes the in-field calibration methods used for the neutron moisture probe measurements and summarizes preliminary results of the monitoring program in the in-situ monitoring network at Area G. Reported results include three main areas: calibration studies, profiles from each of the vertical boreholes at Area G, and time-dependent variations in a select subset of boreholes. Results are reported here for the vertical borehole network. Results from the horizontal borehole network will be described when available.
Date: December 31, 1997
Creator: Vold, E.
Partner: UNT Libraries Government Documents Department

Monitoring and data analysis for the Vadose Zone Monitoring System (VZMS), McClellan AFB. Quarterly status report, May 15, 1997--August 15, 1997

Description: This report contains information on field and laboratory work performed between May 15th and August 15th 1997 at site S-7 in IC 34, at McClellan AFB. At this location, a Vadose Zone Monitoring System (VZMS) is currently being used to collect subsurface data including hydraulic potential, soil gas pressure, moisture content, water chemistry, gas chemistry, and temperature. This report describes: (1) re-calibration of pressure transducers; (2) moisture content changes, based on neutron logging; (3) gas-phase VOC concentrations; (4) aqueous-phase VOC concentrations; (5) temperature profiles; and (6) pressure readings.
Date: August 1, 1997
Creator: Zawislanski, P.T.; Salve, R. & Freifeld, B.
Partner: UNT Libraries Government Documents Department

Calibration models for measuring moisture in unsaturated formations by neutron logging

Description: Calibration models containing known amounts of hydrogen have been constructed to simulate unsaturated earth formations for calibrating neutron well logging tools. The models are made of dry mixtures of hydrated alumina (Al(OH){sub 3}) with either silica sand (SiO{sub 2}) or aluminum oxide (Al{sub 2}O{sub 3}). Hydrogen in the hydrated alumina replaces the hydrogen in water for neutron scattering, making it possible to simulate partially saturated formations. The equivalent water contents for the models are 5%, 12%, 20%, and 40% by volume in seven tanks that have a diameter of 1.5 m and a height of 1.8 m. Steel casings of inside diameter 15.4 cm (for three models) and diameter 20.3 cm (for four models) allow logging tool access to simulate logging through cased boreholes.
Date: October 1995
Creator: Engelman, R. E.; Lewis, R. E. & Stromswold, D. C.
Partner: UNT Libraries Government Documents Department

Shallow infiltration processes at Yucca Mountain, Nevada: Neutron logging data 1984--1993

Description: To determine site suitability of Yucca Mountain, Nevada, as a potential high-level radioactive waste repository, a study was devised to characterize net infiltration. This study involves a detailed data set produced from 99 neutron boreholes that consisted of volumetric water-content readings with depth from 1984 through 1993 at Yucca Mountain. Boreholes were drilled with minimal disturbance to the surrounding soil or rock in order to best represent field conditions. Boreholes were located in topographic positions representing infiltration zones identified as ridgetops, sideslopes, terraces, and active channels. Through careful field calibration, neutron moisture logs, collected on a monthly basis and representing most of the areal locations at Yucca Mountain, illustrated that the depth of penetration of seasonal moisture, important for escaping loss to evapotranspiration, was influenced by several factors. It was increased (1) by thin soil cover, especially in locations where thin soil is underlain by fractured bedrock; (2) on ridgetops; and (3) during the winter when evapotranspiration is low and runoff is less frequent. This data set helps to provide a seasonal and areal distribution of changes in volumetric water content with which to assess hydrologic processes contributing to net infiltration.
Date: December 31, 1995
Creator: Flint, L. E. & Flint, A. L.
Partner: UNT Libraries Government Documents Department

Annual Report RCRA Post-Closure Monitoring and Inspections for CAU 91: Area 3 U-3fi Injection Well, Nevada Test Site, Nevada, for the period October 2000-October 2001

Description: This annual Neutron Soil Moisture Monitoring report provides an analysis and summary for site inspections, meteorological information, and neutron soil moisture monitoring data obtained at the U-3fi Injection Well during the October 2000 to October 2001 period. The U-3fi Injection Well is located in Area 3 of the Nevada Test Site (NTS), Nye County, Nevada. Inspections of the Area 3 U-3fi Injection Well are conducted to determine and document the physical condition of the concrete pad, facilities, and any unusual conditions that could impact the proper operation of the waste disposal unit closure. The objective of the neutron-logging program is to monitor the soil moisture conditions along the 128-meter (m) (420-ft) ER3-3 monitoring well and detect changes that may be indicative of moisture movement in the regulated interval extending between 73 to 82 m (240 to 270 ft) or to detect changes that may be indicative of subsidence within the disposal unit itself.
Date: February 1, 2002
Creator: Tobiason, D. S.
Partner: UNT Libraries Government Documents Department

Annual Report RCRA Post-Closure Monitoring and Inspections for Corrective Action Unit 91: Area 3 U-3fi Injection Well, Nevada Test Site, Nevada, for the Period October 2001 - October 2002

Description: This annual monitoring and inspection report provides an analysis and summary for site inspections, meteorological information, and neutron soil moisture monitoring data obtained at the U-3fi Injection Well during the October 2001 to October 2002 period. The U-3fi Injection Well is located in Area 3 of the Nevada Test Site (NTS), Nye County, Nevada. Inspections of the Area 3 U-3fi Injection Well are conducted to determine and document the physical condition of the concrete pad, facilities, and any unusual conditions that could impact the proper operation of the waste disposal unit closure. The objective of the neutron logging is to monitor the soil moisture conditions along the 128-meter (m) (420-feet [ft]) ER3-3 monitoring well and detect changes that may be indicative of moisture movement in the regulated interval extending between 73 to 82 m (240 to 270 ft).
Date: February 1, 2003
Creator: Richardson, G.
Partner: UNT Libraries Government Documents Department

Calibration of a neutron log in partially saturated media IV: effects of sonde-wall gap

Description: A gap between a neutron sonde and the wall of a borehole can have a significant effect on the observed count rate. This effect was determined experimentally to be linear with gaps as large as 2.5 cm. The count rate is given by N/sub N/ = K/sub 0/ + K/sub 1/g where K/sub 0/ is the count rate that would be observed at zero gap, and g is the gap. The parameters K/sub 0/ and K/sub 1/ are dependent on both water (ie. hydrogen) content and bulk density. In many situations failure to correct the count rate for this gap effect can result in a significant degradation in the accuracy of the water content calculated from the count rate. In a dry borehole, K/sub 1/ is small at zero formation water content, and increases with formation water content. In a water-filled borehole, K/sub 1/ is large at zero formation water content, and tends to decrease with increasing formation water content, becoming zero, as of course it must, if the formation is pure water. The absolute value of K/sub 1/ increases with increasing density. A representation was determined for K/sub 0/ and K/sub 1/ from experimental data. This representation can be used to adjust the count rate at a given gap to equal its zero-gap value. The accuracy of the zero gap equation can then be recovered.
Date: March 8, 1984
Creator: Axelrod, M.C. & Hearst, J.R.
Partner: UNT Libraries Government Documents Department