A Jackknife Approach to Examine Uncertainty and Temporal Change in the Spatial Correlation of a VOC Plume

The application of geostatistics to spatial interpolation of time-invariant properties in ground-water studies (such as transmissivity or aquifer thickness) is well documented. The use of geostatistics on time-variant conditions such as ground-water quality is also becoming more commonplace. Unfortunately, the detection of temporal changes in spatial correlation through direct comparison of experimental semivariograms is difficult due to the uncertainty in sample semivariograms constructed from field data. This paper discusses the use of the jackknife approach to estimate confidence limits of semivariograms of trichloroethane (TC) and other volatile organic compounds (VOC) in contaminated ground-water in northern Illinois. Examination of the ‘spread’ of the confidence limits about the semivariograms created from two types of sampling networks are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42695/1/10661_2004_Article_182073.pd

Engineering Parameters for Four Ignition TNS Tokamak Reactor Systems

The ORNL/Westinghouse program for The Next Step (TNS) tokamak beyond TFTR has examined a large number of potential configurations for D-T burning ignition tokamak systems. An objective of this work has been to quantify the trade-offs associated with the assumption of certain plasma physics criteria and toroidal field coil technologies. Four tokamak system point designs are described, each representative of the TF coil technologies considered, to illustrate the engineering features associated with each concept. Point designs, such as the ones discussed herein, have been used to develop component size, performance and cost scaling relationships which have been incorporated in a digital computer code to facilitate an examination of the total design and cost impact of candidate design approaches. The point designs which are described are typical, however, they have not been individually optimized. The options are distinguished by the TF coil technology chosen and include: (1) a high field water-cooled copper TF system, (2) a moderate field NbTi superconducting TF system, (3) a high field Nb/sub 3/Sn superconducting TF system, and (4) a high field hybrid TF system with outer NbTi superconducting windings and inner water-cooled copper windings. Descriptions are provided for the major device components and all major support systems including power supplies, vacuum systems, fuel systems, heat transport and facility systems

Tory II-C reactor cold critical assembly program

Declassified 27 Nov 1973. The cold critical experiments with the Tory II-C reactor were performed in the critical facility of the Lawrence Radiation Laboratory at Livermore. The reactor is described briefly; the experimental equipment and the arrangement for the experiments is described in detail. The core poison was removed without difficulty, and criticality was achieved at 1624 hours July 14, 1965. With the design core configuration the shutdown margin was less than had been intended; criticality was attained at a shim rod bank position of 38.5 inches insertion rather than the expected 35 inches All Hastelloy tie tubes were replaced by Rene'-41. A heated core experiment with DELTA T = 129 plus or minus 7 deg F above room temperature provided a measure of the temperature coefficient which was found to be --3.9 x 10/sup -3/ plus or minus 7% inch of shim rod bank travel/ deg F. Other experiments included flux mapping, using fission foils, fission counters and copper flux wires, transients to determine control element worths, studies of flux spectrum by means of threshold detectors, and measurements of multiplication for various shutdown configurations for purposes of operational safety. Transient measurements, critical rod configurations, and flux distributions were also measured with the core poisoned in various stages to simulate elevated temperatures. 12 references. (auth

TNS quarterly progress report, January--March 1977

The TNS effort during the January-February-March, 1977 period included the completion of the first iteration of an assessment of the Research, Development and Demonstration needs for TNS and further development of system size and cost models to support TF coil technology and plasma size trade studies. The following material highlights key accomplishments during the quarter which are discussed in greater detail in subsequent sections

Qualification of primary loop manifold of a liquid metal thermoelectric converter

The mechanical cycling test was required to verify the integrity of the welded joints and the thin wall tube bends in the primary loop manifold assembly of a four pack thermo electric module and to help establish structural and mechanical requirements of any possible redesign. The test section was subjected to more severe loading conditions than will be experienced during actual operating conditions. The test was a mechanical simulation of the differential thermal expansion which occurs due to the approximately 600{degrees} F temperature differential in the subassembly. The actual load exerted on the test section represented this deflection. The effects on the joints and tube material were observed. The test was conducted on a test segment of manifold designed to duplicate two of the flexible elbows; the transition joints between the elbows and the tubular module inner clad; and the welded joints of the elbows to the primary loop header. The assembled test segment and hold-down bracket are shown. The bracket was mounted to the base of the Universal Test Machine. Dial indicators measured the relative displacement between the line of applied load (through the vertical axis of the primary loop header) and the attachment point at the holddown bracket. In the first test, the load was applied in fifty pound increments until the relative displacement of nine mils was measured between the loop header and the welded joint on the feedline elbow. The remaining tests were cycling the header assembly at increasing relative displace ment. The summary of these tests are tabulated. The testing had no noticeable affect on the structural integrity of the weldment

Bayesian methodology to stochastic capture zone determination : conditioning on transmissivity measurements.

A methodology to determine the uncertainty associated with the delineation of well capture zones in heterogeneous aquifers is presented. The log transmissivity field is modeled as a random space function and the Bayesian paradigm accounts for the uncertainty that stems from the imperfect knowledge about the parameters of the stochastic model. Unknown parameters are treated as random quantities and characterized by a prior probability distribution. Log transmissivity measurements are incorporated into Bayes' theorem, updating the prior distribution and yielding posterior estimates of the mean value and the covariance parameters of the log transmissivity. Conditional simulations of the log transmissivity field are generated using samples from the posterior distribution of the parameters, yielding samples from the predictive distribution of the log transmissivity field. The uncertainty in the model parameters is propagated to the predictive uncertainty of the capture zone by solving numerically the groundwater flow equation, followed by a semianalytical particle-tracking algorithm. The method is applied to a set of hypothetical flow fields for various sampling densities and assuming different levels of parameter uncertainty. Simulation results for all the sampling densities show no univocal relation between the predictive uncertainty of the capture zones and the level of parameter uncertainty. However, in general, the predictive uncertainty increases when parameter uncertainty is taken into account