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Evaluation of kriging techniques for high level radioactive waste repository site characterization

Description: Kriging is a statistical method for estimating functions that describe spatially distributed phenomena such as groundwater elevation and depth to basalt. It produces a contour model of the geologic formation of a potential site with an associated measure of uncertainty, and it can be used to optimize the selection of additional sampling locations. Kriging was applied to water potential data and top-of-basalt elevations from the Hanford site; the computer code BLUEPACK was used to perform the computations. The water potential contours were in close agreement with a hand-drawn contour map which is used as a standard. It is concluded that kriging can be a useful tool for geologic waste repository site characterization. (DLC)
Date: January 1, 1979
Creator: Doctor, P.G.
Partner: UNT Libraries Government Documents Department

Geostatistical Modeling of Pore Velocity

Description: A significant part of evaluating a geologic formation as a nuclear waste repository involves the modeling of contaminant transport in the surrounding media in the event the repository is breached. The commonly used contaminant transport models are deterministic. However, the spatial variability of hydrologic field parameters introduces uncertainties into contaminant transport predictions. This paper discusses the application of geostatistical techniques to the modeling of spatially varying hydrologic field parameters required as input to contaminant transport analyses. Kriging estimation techniques were applied to Hanford Reservation field data to calculate hydraulic conductivity and the ground-water potential gradients. These quantities were statistically combined to estimate the groundwater pore velocity and to characterize the pore velocity estimation error. Combining geostatistical modeling techniques with product error propagation techniques results in an effective stochastic characterization of groundwater pore velocity, a hydrologic parameter required for contaminant transport analyses.
Date: June 1, 1981
Creator: Devary, J.L. & Doctor, P.G.
Partner: UNT Libraries Government Documents Department

Pattern recognition methods for acoustic emission analysis

Description: Models have been developed that relate the rate of acoustic emissions to structural integrity. The implementation of these techniques in the field has been hindered by the noisy environment in which the data must be taken. Acoustic emissions from noncritical sources are recorded in addition to those produced by critical sources, such as flaws. A technique is discussed for prescreening acoustic events and filtering out those that are produced by noncritical sources. The methodology that was investigated is pattern recognition. Three different pattern recognition techniques were applied to a data set that consisted of acoustic emissions caused by crack growth and acoustic signals caused by extraneous noise sources. Examination of the acoustic emission data presented has uncovered several features of the data that can provide a reasonable filter. Two of the most valuable features are the frequency of maximum response and the autocorrelation coefficient at Lag 13. When these two features and several others were combined with a least squares decision algorithm, 90% of the acoustic emissions in the data set were correctly classified. It appears possible to design filters that eliminate extraneous noise sources from flaw-growth acoustic emissions using pattern recognition techniques.
Date: July 1, 1979
Creator: Doctor, P.G.; Harrington, T.P. & Hutton, P.H.
Partner: UNT Libraries Government Documents Department

Statistical activities during 1976 and the design and initial analysis of nuclear site studies. [/sup 241/Am, /sup 137/Cs, /sup 239/Pu, /sup 240/Pu]

Description: Statistical design and analysis activities for the Nevada Applied Ecology Group (NAEG) during 1976 are briefly outlined. This is followed by a description of soil data collected thus far at nuclear study sites. Radionuclide concentrations in surface soil collected along a transect from ground zero (GZ) along the main fallout pattern are given for Nuclear Site (NS) 201. Concentrations in soil collected at 315 locations on a grid system at 200 foot spacings are also given for this site. The /sup 241/Am to /sup 137/Cs ratios change over NS 201 depending on location relative to GZ. They range from less than one where /sup 241/Am is at low levels, to more than fifty where /sup 241/Am levels are high (near GZ). The estimated median /sup 239/ /sup 240/Pu to /sup 241/Am ratio is 11 and appears to be relatively constant over the area (the 95 percent lower and upper limits on the true median ratio are about 8 and 14).
Date: May 1, 1977
Creator: Gilbert, R O; Essington, E H; Brady, D N; Doctor, P G & Eberhardt, L L
Partner: UNT Libraries Government Documents Department

Pacific Northwest Laboratory annual report for 1989 to the Assistant Secretary for Environment, Safety, and Health - Part 5: Environment, Safety, Health, and Quality Assurance

Description: Part 5 of the 1989 Annual Report to the US Department of Energy's Assistant Secretary for Environment, Safety, and Health presents Pacific Northwest Laboratory's progress on work performed for the Office of Environmental Guidance and Compliance, the Office of Environmental Audit, the Office of National Environmental Policy Act Project Assistance, the Office of Nuclear Safety, the Office of Safety Compliance, and the Office of Policy and Standards. For each project, as identified by the Field Work Proposal, there is an article describing progress made during fiscal year 1989. Authors of these articles represent a broad spectrum of capabilities derived from five of the seven technical centers of the Laboratory, reflecting the interdisciplinary nature of the work. 35 refs., 1 fig.
Date: April 1, 1990
Creator: Faust, L.G.; Doctor, P.G. & Selby, J.M.
Partner: UNT Libraries Government Documents Department

Steam generator group project: Task 13 final report: Nondestructive examination validation

Description: The Steam Generator Group Project (SGGP) was a multi-task effort using the retired-from-service Surry 2A pressurized water reactor steam generator as a test bed to investigate the reliability and effectiveness of in-service nondestructive eddy current (EC) inspection equipment and procedures. The information developed provided the technical basis for recommendations for improved in- service inspection and tube plugging criteria of steam generators. This report describes the results and analysis from Task 13--NDE Validation. The primary objective of Task 13 was to validate the EC inspection to detect and size tube defects. Additional objectives were to assess the nature and severity of tube degradation from all regions of the generator and to measure the remaining integrity of degraded specimens by burst testing. More than 550 specimens were removed from the generator and included in the validation studies. The bases for selecting the specimens and the methods and procedures used for specimen removal from the generator are reported. Results from metallurgical examinations of these specimens are presented and discussed. These examinations include visual inspection of all specimens to locate and identify tube degradation, metallographic examination of selected specimens to establish defect severity and burst testing of selected specimens to establish the remaining integrity of service-degraded tubes. Statistical analysis of the combined metallurgical and EC data to determine the probability of detection (POD) and sizing accuracy are reported along with a discussion of the factors which influenced the EC results. Finally, listings of the metallurgical and corresponding EC data bases are given. 12 refs., 141 figs., 24 tabs.
Date: August 1, 1988
Creator: Bradley, E.R.; Doctor, P.G.; Ferris, R.H. & Buchanan, J.A.
Partner: UNT Libraries Government Documents Department

Multimedia Environmental Pollutant Assessment System (MEPAS) sensitivity analysis of computer codes

Description: The Multimedia Environmental Pollutant Assessment System (MEPAS) is a computer-based methodology developed by the Pacific Northwest Laboratory (PNL) for the US Department of Energy (DOE) to estimate health impacts from the release of hazardous chemicals and radioactive materials. The health impacts are estimated from the environmental inventory and release or emission rate, constituent transport, constituent uptake and toxicity, and exposure route parameters. As part of MEPAS development and evaluation, PNL performed a formal parametric sensitivity analysis to determine the sensitivity of the model output to the input parameters, and to provide a systematic and objective method for determining the relative importance of the input parameters. The sensitivity analysis determined the sensitivity of the Hazard Potential Index (HPI) values to combinations of transport pathway and exposure routes important to evaluating environmental problems at DOE sites. Two combinations of transport pathways and exposure routes were evaluated. The sensitivity analysis focused on evaluating the effect of variation in user-specified parameters, such as constituent inventory, release and emission rates, and parameters describing the transport and exposure routes. The constituents used were strontium-90, yttrium-90, tritium, arsenic, mercury, polychlorinated biphenyls, toluene, and perchloroethylene. 28 refs., 3 figs., 46 tabs.
Date: April 1, 1990
Creator: Doctor, P.G.; Miley, T.B. & Cowan, C.E.
Partner: UNT Libraries Government Documents Department

Steam Generator Group Project. Progress report on data acquisition/statistical analysis

Description: A major task of the Steam Generator Group Project (SGGP) is to establish the reliability of the eddy current inservice inspections of PWR steam generator tubing, by comparing the eddy current data to the actual physical condition of the tubes via destructive analyses. This report describes the plans for the computer systems needed to acquire, store and analyze the diverse data to be collected during the project. The real-time acquisition of the baseline eddy current inspection data will be handled using a specially designed data acquisition computer system based on a Digital Equipment Corporation (DEC) PDP-11/44. The data will be archived in digital form for use after the project is completed. Data base management and statistical analyses will be done on a DEC VAX-11/780. Color graphics will be heavily used to summarize the data and the results of the analyses. The report describes the data that will be taken during the project and the statistical methods that will be used to analyze the data. 7 figures, 2 tables.
Date: January 1, 1984
Creator: Doctor, P.G.; Buchanan, J.A.; McIntyre, J.M.; Hof, P.J. & Ercanbrack, S.S.
Partner: UNT Libraries Government Documents Department

Technology demonstration: geostatistical and hydrologic analysis of salt areas. Assessment of effectiveness of geologic isolation systems

Description: The Office of Nuclear Waste Isolation (ONWI) requested Pacific Northwest Laboratory (PNL) to: (1) use geostatistical analyses to evaluate the adequacy of hydrologic data from three salt regions, each of which contains a potential nuclear waste repository site; and (2) demonstrate a methodology that allows quantification of the value of additional data collection. The three regions examined are the Paradox Basin in Utah, the Permian Basin in Texas, and the Mississippi Study Area. Additional and new data became available to ONWI during and following these analyses; therefore, this report must be considered a methodology demonstration here would apply as illustrated had the complete data sets been available. A combination of geostatistical and hydrologic analyses was used for this demonstration. Geostatistical analyses provided an optimal estimate of the potentiometric surface from the available data, a measure of the uncertainty of that estimate, and a means for selecting and evaluating the location of future data. The hydrologic analyses included the calculation of transmissivities, flow paths, travel times, and ground-water flow rates from hypothetical repository sites. Simulation techniques were used to evaluate the effect of optimally located future data on the potentiometric surface, flow lines, travel times, and flow rates. Data availability, quality, quantity, and conformance with model assumptions differed in each of the salt areas. Report highlights for the three locations are given.
Date: September 1, 1982
Creator: Doctor, P.G.; Oberlander, P.L.; Rice, W.A.; Devary, J.L.; Nelson, R.W. & Tucker, P.E.
Partner: UNT Libraries Government Documents Department

Some Aspects of Cost/ Benefit Analysis for In-Service Inspection of PWR Steam Generators

Description: This report discusses a number of aspects of cost/benefit (C/B) analysis for in-service inspection (lSI} of pressurized water reactor (PWR) steam generators (SGs) and identifies several problem areas that must be addressed prior to a full C/B analysis capability. Following a brief review of the impact of SG problems on the productivity of PWR units and of the scope and variability of SG problems among U.S. PWRs, various occupational implications of SG lSI are considered, namely manpower, time, and rad exposure. The opportunities provided by refueling outages in respect to lSI frequency and work time windows are reviewed. Indices for characterizing the nondestructive testing {NDT) information, rad exposure, $ impact, and manpower and time attributes of single ISIs and a series of ISIs over an arbitrary evaluation period are presented and calculated for a number of lSI cases using SG parameters for three typical PWR units. A comparison of the $ impact of unscheduled outages attributable to SG problems with the $ cost of ambitious lSI strategies indicates that the $ cost is virtually negligible for well-planned ISis. Considering the ALARA constraint on occupational rad exposure, the skilled manpower pool for NDT work appears to be the principal factor limiting lSI scope and frequency. Analysis of the manpower and time requirements for inspection of a 40-unit PWR population indicates, however, that an lSI strategy embodying two campaigns per year and a total population inspection within a 2-year interval is not far beyond current capabilities.
Date: May 1, 1981
Creator: Zima, G. E.; Lyon, G. H.; Doctor, P. G.; Hoenes, G. R.; Petty, S. E. & Weakley, S. A.
Partner: UNT Libraries Government Documents Department

Characterization strategy report for the criticality safety issue

Description: High-level radioactive waste from nuclear fuels processing is stored in underground waste storage tanks located in the tank farms on the Hanford Site. Waste in tank storage contains low concentrations of fissile isotopes, primarily U-235 and Pu-239. The composition and the distribution of the waste components within the storage environment is highly complex and not subject to easy investigation. An important safety concern is the preclusion of a self-sustaining neutron chain reaction, also known as a nuclear criticality. A thorough technical evaluation of processes, phenomena, and conditions is required to make sure that subcriticality will be ensured for both current and future tank operations. Subcriticality limits must be based on considerations of tank processes and take into account all chemical and geometrical phenomena that are occurring in the tanks. The important chemical and physical phenomena are those capable of influencing the mixing of fissile material and neutron absorbers such that the degree of subcriticality could be adversely impacted. This report describes a logical approach to resolving the criticality safety issues in the Hanford waste tanks. The approach uses a structured logic diagram (SLD) to identify the characterization needed to quantify risk. The scope of this section of the report is limited to those branches of logic needed to quantify the risk associated with a criticality event occurring. The process is linked to a conceptual model that depicts key modes of failure which are linked to the SLD. Data that are needed include adequate knowledge of the chemical and geometric form of the materials of interest. This information is used to determine how much energy the waste would release in the various domains of the tank, the toxicity of the region associated with a criticality event, and the probability of the initiating criticality event.
Date: June 1, 1997
Creator: Doherty, A.L.; Doctor, P.G.; Felmy, A.R.; Prichard, A.W. & Serne, R.J.
Partner: UNT Libraries Government Documents Department

Computer-based tools for decision support at the Hanford Site

Description: To help integrate activities in the environmental restoration and waste management mission of the Hanford Site, the Hanford Integrated Planning Project (HIPP) was established and funded by the US Department of Energy. The project is divided into three key program elements, the first focusing on an explicit, defensible and comprehensive method for evaluating technical options. Based on the premise that computer technology can be used to support the decision-making process and facilitate integration among programs and activities, the Decision Support Tools Task was charged with assessing the status of computer technology for those purposes at the Site. The task addressed two types of tools: tools need to provide technical information and management support tools. Technical tools include performance and risk assessment models, information management systems, data and the computer infrastructure to supports models, data, and information management systems. Management decision support tools are used to synthesize information at a high' level to assist with making decisions. The major conclusions resulting from the assessment are that there is much technical information available, but it is not reaching the decision-makers in a form to be used. Many existing tools provide components that are needed to integrate site activities; however, some components are missing and, more importantly, the glue'' or connections to tie the components together to answer decision-makers questions is largely absent. Top priority should be given to decision support tools that support activities given in the TPA. Other decision tools are needed to facilitate and support the environmental restoration and waste management mission.
Date: November 1, 1992
Creator: Doctor, P.G.; Mahaffey, J.A.; Cowley, P.J.; Freshley, M.D.; Hassig, N.L.; Brothers, J.W. et al.
Partner: UNT Libraries Government Documents Department

An example postclosure risk assessment using the potential Yucca Mountain Site

Description: The risk analysis described in this document was performed for the US Department of Energy`s (DOE) Office of Civilian Radioactive Waste Management (OCRWM) over a 2-year time period ending in June 1988. The objective of Pacific Northwest Laboratory`s (PNL) task was to demonstrate an integrated, though preliminary, modeling approach for estimating the postclosure risk associated with a geologic repository for the disposal of high-level nuclear waste. The modeling study used published characterization data for the proposed candidate site at Yucca Mountain, Nevada, along with existing models and computer codes available at that time. Some of the site data and conceptual models reported in the Site Characterization Plan published in December 1988, however, were not yet available at the time that PNL conducted the modeling studies.
Date: May 1, 1992
Creator: Doctor, P.G.; Eslinger, P.W.; Elwood, D.M.; Engel, D.W.; Freshley, M.D.; Liebetrau, A.M. et al.
Partner: UNT Libraries Government Documents Department

A strategic analysis study-based approach to integrated risk assessment: Occupational health risks from environmental restoration and waste management activities at Hanford

Description: The goal of environmental restoration and waste management activities is to reduce public health risks or to delay risks to the future when new technology will be available for improved cleanup solutions. Actions to remediate the wastes on the Hanford Site will entail risks to workers, the public, and the environment that do not currently exist. In some circumstances, remediation activities will create new exposure pathways that are not present without cleanup activities. In addition, cleanup actions will redistribute existing health risks over time and space, and will likely shift health risks to cleanup workers in the short term. This report describes an approach to occupational risk assessment based on the Hanford Strategic Analysis Study and illustrates the approach by comparing worker risks for two options for remediation of N/K fuels, a subcategory of unprocessed irradiated fuels at Hanford.
Date: June 1, 1993
Creator: Mahaffey, J.A.; Doctor, P.G.; Buschbom, R.L.; Glantz, C.S.; Daling, P.M.; Sever, L.E. et al.
Partner: UNT Libraries Government Documents Department