24 Matching Results

Search Results

Advanced search parameters have been applied.

Quality control and assurance applied to the analysis of environmental samples collected from known geothermal sites. Final report

Description: The components of an analytical quality control and assurance program for the analysis of trace toxic and priority pollutants are reviewed in general. It is recommended that these principles be applied to develop increased confidence in a laboratory's analytical accuracy by establishing validated standard operating procedures with built in controls and internal cross checks and developing an approved standard operating procedure for quality assurance consisting of audits and appropriate documentation. It is recommended that interlaboratory comparisons be considered as a means of continually documenting analytical accuracy.
Date: January 31, 1978
Creator: Cooper, J.A.
Partner: UNT Libraries Government Documents Department

The use of fuzzy mathematics in subjective uncertainty analysis

Description: We have been investigating the applicability of fuzzy mathematics in safety assessments (PSAs). It is a very efficient approach, both in terms of methodology development time and program execution time. Most importantly, it processes subjective information subjectively, not as if it were based on measured data. One of the most useful results of this work is that we have shown the potential for significant differences (especially in perceived margin relative to a decision threshold) between fuzzy mathematics analysis and conventional PSA analysis. This difference is due to subtle factors inherent in the choice of probability distributions for modeling uncertainty. Since subjective uncertainty, stochastic variability, and dependence are all parts of most practical situations, a technique has been developed for combining the three effects. The methodology is based on hybrid numbers and on Frechet inequality dependency bounds analysis. Some new results have also been obtained in the areas of efficient disjoint set representations and constrained uncertainty and variability analysis.
Date: June 1, 1996
Creator: Cooper, J.A.
Partner: UNT Libraries Government Documents Department

PHASER 2.10 methodology for dependence, importance, and sensitivity: The role of scale factors, confidence factors, and extremes

Description: PHASER (Probabilistic Hybrid Analytical System Evaluation Routine) is a software tool that has the capability of incorporating subjective expert judgment into probabilistic safety analysis (PSA) along with conventional data inputs. An earlier report described the PHASER methodology, but only gave a cursory explanation about how dependence was incorporated in Version 1.10 and about how ``Importance`` and ``Sensitivity`` measures were to be incorporated in Version 2.00. A more detailed description is given in this report. The basic concepts involve scale factors and confidence factors that are associated with the stochastic variability and subjective uncertainty (which are common adjuncts used in PSA), and the safety risk extremes that are crucial to safety assessment. These are all utilized to illustrate methodology for incorporating dependence among analysis variables in generating PSA results, and for Importance and Sensitivity measures associated with the results that help point out where any major sources of safety concern arise and where any major sources of uncertainty reside, respectively.
Date: September 1, 1996
Creator: Cooper, J.A.
Partner: UNT Libraries Government Documents Department

Hybrid Blends of Non-Traditional Safety and Reliability Analysis Tools

Description: Traditional safety and reliability analysis methods are applicable to many standard problems, including those examples illustrated in most formal courses. However, there are many real-world situations for which non-traditional methods appear to be more appropriate, mainly because most practical problems involve substantial subjectivity about the inputs and models used. This paper surveys some of the most applicable approaches found in a recent research study. Each approach is developed individually and is illuminated by selecting example situations of apparent applicability. Then, the combinational blending of the approaches with each other and with traditional methodology is discussed.
Date: April 21, 1999
Creator: Cooper, J.A.
Partner: UNT Libraries Government Documents Department

System safety based on a coordinated principle-based theme

Description: In this paper, the authors demonstrate a logical progression for the identification of assets, threats, vulnerabilities, and protective measures, based on a structured approach that incorporates the results of the previous paper. The authors utilize a logical structure for identifying the constituents of the problem, derive appropriate applicable principles, and demonstrate a technique for incorporating the principles into a coordinated safety theme. They also show how to qualitatively assess such generally non-quantifiable items such as safety-component and safety-system response to severe abnormal environments. An illustrative example is followed step-by-step through to a safety system design approach and a safety assessment approach. The general approach is illustrated here through an example, generally representing a test rocket launch scenario, where the concern is the potential for loss of life.
Date: August 1, 1998
Creator: Cooper, J.A.
Partner: UNT Libraries Government Documents Department

Independent communication messages: methodology and applications

Description: Information flowing on communication buses is ordinarily ``non-random`` in the sense that data entities are not equally likely and independent. This is because they have relationships to each other and to physical occurrences to which they may be responding. Random data would convey no information or meaning. From a different viewpoint, there can be applications for creating randomness characteristics, and four of these are described in this paper. Two examples derive from cryptology and the other two from safety. One cryptology application described is the generation of random numbers for use as, for example, keys, hash functions, nonces, and seeds. The other is for inter-message ``padding`` to resist traffic analysis by masking when data are being transmitted and when the channel is conveying no information. One of the safety applications described is the ``unique signal`` approach used in modern nuclear weapon electrical safety. The other is the use of unique signals as non-weapon critical-operation control functions. Both of these safety applications require provisions to help assure randomness characteristics in any inadvertently occurring inputs. In order to satisfy these cryptology and safety needs, communication strategies are described that generate or selectively encourage independent (unrelated) symbols or messages.
Date: September 1, 1997
Creator: Cooper, J.A.
Partner: UNT Libraries Government Documents Department

Theoretical description of methodology in PHASER (Probabilistic hybrid analytical system evaluation routine)

Description: Probabilistic safety analyses (PSAs) frequently depend on fault tree and event tree models, using probabilities of `events` for inputs. Uncertainty or variability is sometimes included by assuming that the input probabilities vary independently and according to an assumed stochastic probability distribution modes. Evidence is accumulating that this methodology does not apply well to some situations, most significantly when the inputs contain a degree of subjectivity or are dependent. This report documents the current status of an investigation into methods for effectively incorporating subjectivity and dependence in PSAs and into the possibility of incorporating inputs that are partly subjective and partly stochastic. One important byproduct of this investigation was a computer routine that combines conventional PSA techniques with newly developed subjective techniques in a `hybrid` (subjective and conventional PSA) program. This program (PHASER) and a user`s manual are now available for beta use.
Date: January 1, 1996
Creator: Cooper, J.A.
Partner: UNT Libraries Government Documents Department

Investigation of Minytrema melanops mortality in Woods Reservoir near the CFFF

Description: The Department of Energy MHD Coal-Fired Flow Facility is located on Woods Reservoir at the University of Tennessee Space Institute. Part of the role of UTSI as participants in the DOE program is to document environmental aspects of coal-fired MHD. This document reports the findings of UTSI in investigating a fish kill on Woods Reservoir. The results show the fish mortality to be of natural causes, in no way attributable to CFFF operations. Occasionally seasonal fish kills have occurred in Woods Reservoir during the past several years with minimal documentation of causative factors. During the early spring (April 1980) approximately one hundred fish of a single species Minytrema (spotted sucker) died near the embayment of Rollins Creek. An investigation was conducted to determine the cause of death. Inasmuch as only a single species was involved it was assumed that the kill resulted from an infectious or parasitic disease rather than from pollution. This view was substantiated by an examination of the water quality data during the period. Specimens were examined macroscopically and microscopically for external and internal pathogens. Heavy infestation of the myxosporidian spore Myxosoma sp. was found localized in the gills of the fish. Scanning electron photomicrographs revealed a heavy infection by the spores and this coupled with the stress of spring spawning was concluded to be a contributing factor in the death of M. melanops.
Date: July 1, 1980
Creator: Cooper, J. A.
Partner: UNT Libraries Government Documents Department

Fuzzy-algebra uncertainty analysis for abnormal-environment safety assessment

Description: Many safety (risk) analyses depend on uncertain inputs and on mathematical models chosen from various alternatives, but give fixed results (implying no uncertainty). Conventional uncertainty analyses help, but are also based on assumptions and models, the accuracy of which may be difficult to assure. Some of the models and assumptions that on cursory examination seem reasonable can be misleading. As a result, quantitative assessments, even those accompanied by uncertainty measures, can give unwarranted impressions of accuracy. Since analysis results can be a major contributor to a safety-measure decision process, risk management depends on relating uncertainty to only the information available. The uncertainties due to abnormal environments are even more challenging than those in normal-environment safety assessments, and therefore require an even more cautious approach. A fuzzy algebra analysis is proposed in this report that has the potential to appropriately reflect the information available and portray uncertainties well, especially for abnormal environments.
Date: January 1, 1994
Creator: Cooper, J. A.
Partner: UNT Libraries Government Documents Department

An examination of the consequences in high consequence operations

Description: Traditional definitions of risk partition concern into the probability of occurrence and the consequence of the event. Most safety analyses focus on probabilistic assessment of an occurrence and the amount of some measurable result of the event, but the real meaning of the ``consequence`` partition is usually afforded less attention. In particular, acceptable social consequence (consequence accepted by the public) frequently differs significantly from the metrics commonly proposed by risk analysts. This paper addresses some of the important system development issues associated with consequences, focusing on ``high consequence operations safety.``
Date: June 1, 1996
Creator: Spray, S.D. & Cooper, J.A.
Partner: UNT Libraries Government Documents Department

New Mathematical Derivations Applicable to Safety and Reliability Analysis

Description: Boolean logic expressions are often derived in safety and reliability analysis. Since the values of the operands are rarely exact, accounting for uncertainty with the tightest justifiable bounds is important. Accurate determination of result bounds is difficult when the inputs have constraints. One example of a constraint is that an uncertain variable that appears multiple times in a Boolean expression must always have the same value, although the value cannot be exactly specified. A solution for this repeated variable problem is demonstrated for two Boolean classes. The classes, termed functions with unate variables (including, but not limited to unate functions), and exclusive-or functions, frequently appear in Boolean equations for uncertain outcomes portrayed by logic trees (event trees and fault trees).
Date: April 19, 1999
Creator: Cooper, J.A. & Ferson, S.
Partner: UNT Libraries Government Documents Department

Passive safety concepts applied to critical functions

Description: Safety is of paramount concern in todays high technology environment. Because of technological advances, there are numerous situations (high consequence operations) for which the implications of a safety failure are so severe that extreme attention to safety systems is essential. Some of those situations are: nuclear weapon detonation safety, nuclear reactor safety, dam safety, mass transit transportation safety, and hazardous materials transportation and handling safety. In each case, specific safety systems, human control, and administrative procedures have been designed to give a high level of assurance against disasters. In an overview sense, safety concepts can be divided into two broad approaches: active safety and passive safety. Active safety systems, in general, are based on the need for ``functioning`` elements (operating motors, operator action, etc.) and safety may be based in a large measure on ``reliability`` data (historical records of the operability success of components). Passive safety basically depends on non-functionality.
Date: March 1, 1995
Creator: Spray, S.D. & Cooper, J.A.
Partner: UNT Libraries Government Documents Department

Fuzzy-algebra uncertainty assessment

Description: A significant number of analytical problems (for example, abnormal-environment safety analysis) depend on data that are partly or mostly subjective. Since fuzzy algebra depends on subjective operands, we have been investigating its applicability to these forms of assessment, particularly for portraying uncertainty in the results of PRA (probabilistic risk analysis) and in risk-analysis-aided decision-making. Since analysis results can be a major contributor to a safety-measure decision process, risk management depends on relating uncertainty to only known (not assumed) information. The uncertainties due to abnormal environments are even more challenging than those in normal-environment safety assessments; and therefore require an even more judicious approach. Fuzzy algebra matches these requirements well. One of the most useful aspects of this work is that we have shown the potential for significant differences (especially in perceived margin relative to a decision threshold) between fuzzy assessment and probabilistic assessment based on subtle factors inherent in the choice of probability distribution models. We have also shown the relation of fuzzy algebra assessment to ``bounds`` analysis, as well as a description of how analyses can migrate from bounds analysis to fuzzy-algebra analysis, and to probabilistic analysis as information about the process to be analyzed is obtained. Instructive examples are used to illustrate the points.
Date: December 1, 1994
Creator: Cooper, J. A. & Cooper, D. K.
Partner: UNT Libraries Government Documents Department

The unique signal concept for detonation safety in nuclear weapons

Description: The purpose of a unique signal (UQS) in a nuclear weapon system is to provide an unambiguous communication of intent to detonate from the UQS information input source device to a stronglink safety device in the weapon in a manner that is highly unlikely to be duplicated or simulated in normal environments and in a broad range of ill-defined abnormal environments. This report presents safety considerations for the design and implementation of UQSs in the context of the overall safety system.
Date: June 1, 1993
Creator: Spray, S. D. & Cooper, J. A.
Partner: UNT Libraries Government Documents Department

Hybrid processing of stochastic and subjective uncertainty data

Description: Uncertainty analyses typically recognize separate stochastic and subjective sources of uncertainty, but do not systematically combine the two, although a large amount of data used in analyses is partly stochastic and partly subjective. We have developed methodology for mathematically combining stochastic and subjective data uncertainty, based on new ``hybrid number`` approaches. The methodology can be utilized in conjunction with various traditional techniques, such as PRA (probabilistic risk assessment) and risk analysis decision support. Hybrid numbers have been previously examined as a potential method to represent combinations of stochastic and subjective information, but mathematical processing has been impeded by the requirements inherent in the structure of the numbers, e.g., there was no known way to multiply hybrids. In this paper, we will demonstrate methods for calculating with hybrid numbers that avoid the difficulties. By formulating a hybrid number as a probability distribution that is only fuzzy known, or alternatively as a random distribution of fuzzy numbers, methods are demonstrated for the full suite of arithmetic operations, permitting complex mathematical calculations. It will be shown how information about relative subjectivity (the ratio of subjective to stochastic knowledge about a particular datum) can be incorporated. Techniques are also developed for conveying uncertainty information visually, so that the stochastic and subjective constituents of the uncertainty, as well as the ratio of knowledge about the two, are readily apparent. The techniques demonstrated have the capability to process uncertainty information for independent, uncorrelated data, and for some types of dependent and correlated data. Example applications are suggested, illustrative problems are worked, and graphical results are given.
Date: November 1, 1995
Creator: Cooper, J.A.; Ferson, S. & Ginzburg, L.
Partner: UNT Libraries Government Documents Department

Constrained Mathematics for Calculating Logical Safety and Reliability Probabilities with Uncertain Inputs

Description: Calculating safety and reliability probabilities with functions of uncertain variables can yield incorrect or misleading results if some precautions are not taken. One important consideration is the application of constrained mathematics for calculating probabilities for functions that contain repeated variables. This paper includes a description of the problem and develops a methodology for obtaining an accurate solution.
Date: January 21, 1999
Creator: Cooper, D.K.; Cooper, J.A. & Ferson, S.
Partner: UNT Libraries Government Documents Department

Improving analytical understanding through the addition of information: Bayesian and hybrid mathematics approaches

Description: Safety analysts frequently must provide results that are based on sparse (or even no) data. When data (or more data) become available, it is important to utilize the new information optimally in improving the analysis results. Two methods for accomplishing this purpose are Bayesian analysis, where "prior" probability distributions are modified to become "posterior" distributions based on the new data, and hybrid (possibilistic/probabilistic analysis) where possibilistic "membership" portrays the subjectivity involved and the probabilistic analysis is "frequentist." Each of these approaches has interesting features, and it is advantageous to compare and contrast the two. In addition to describing and contrasting these two approaches, we will discuss how features of each can be combined to give new advantages neither offers by itself.
Date: September 13, 1998
Creator: Cooper, J.A. & Diegert, K.V.
Partner: UNT Libraries Government Documents Department

Characteristics of attached radon-222 daughters under both laboratory and underground uranium-mine environments

Description: The organic, inorganic, and radiological characteristics of airborne aerosols have been measured as a function of particle size in controlled atmosphere test chambers and operating uranium mines. Concentrations of benzo(a)pyrene in two mines ranged from 26 to 57 ng/m/sup 3/ of air. The carbon chain length of adsorbed n-alkanes was correlated with particle size. Normal mining activities produced an ore dust aerosol with mass median aerodynamic diameter (MMAD) greater than 2 ..mu..m. The elements Na, Al, Si, K, Ca, Ti, V, Fe, and U exhibited elemental ratios similar to bulk ore and had comparable MMAD's. The S, Zn, and Pb were higher in aerosols than bulk ore and were associated with smaller MMAD particulates. Radon daughter particle size distributions were influenced by the kinds of particulates generated in mining activity.
Date: September 1, 1981
Creator: Jackson, P.O.; Cooper, J.A.; Langford, J.C. & Petersen, M.R.
Partner: UNT Libraries Government Documents Department

Potential Disadvantages of Microtechnology for Future High Consequence Safety Applications

Description: Microtechnologies (e.g., microelectronics, and micromachines) are useful and promising for many applications. However, since the small size and specialized materials of electronics in general and microtechnologies in particular appear to make them sensitive to many normal and abnormal environments, and since complete characterization of the newer technologies is lacking, they must be used with extreme caution in high consequence safety applications. Based on what is now known, we believe that they should not be proposed for high consequence safety applications, particularly for nuclear weapons detonation safety.
Date: December 18, 1998
Creator: Caldwell, M.; Cooper, J.A.; Covan, J.M.; D'Antonio, P.E. & Spray, S.D.
Partner: UNT Libraries Government Documents Department

Toxic emissions from a cyclone burner boiler with an ESP and with the SNOX demonstration and from a pulverized coal burner boiler with an ESP/wet flue gas desulfurization system

Description: Emission factors for VOC and aldehydes, dioxins/furans, and PAH/SVOC are presented in Tables 6--8, respectively. Each table includes results for Coal Creek, Niles Boiler, and the SNOX process. As shown in Table 6, benzene and toluene were measured in the Coal Creek, Niles Boiler, and SNOX stack emissions in highly variable concentrations. Over 90 percent of the VOC analyzed were not detected in the stack gases, and the emission factor for these VOC ranges from 1.1 to 1.4 {mu}g/MJ for the three systems. Emission factors for the four aldehydes that were measured range from 0.47 to 31 {mu}g/MJ for Coal Creek, 1.7 to 38 {mu}g/MJ for the Niles Boiler, and 3.6 to 167 {mu}g/MJ for the SNOX process. Acetaldehyde is at the highest concentration of the four aldehydes in all three units, a finding which is consistent with previous work. Dioxin/furan emission factors are provided in Table 7. Emission, factors for these compounds range from 0.40 to 6.51 pg/MJ for Coal Creek and 0.45 to 8.14 pg/MJ for the Niles Boiler. Dioxins/furans were not determined in the SNOX process. The compounds 1,2,3,4,6,7,8heptachlorodibenzo-p-dioxin, octachlorodibenzo-p-dioxin, and 2,3,7,8-tetrachlorodibenzofuran were detected in both units. The predominance of these species in high SO{sub 2} environments has been previously observed. All other 2,3,7,8 substituted dioxin/furan isomers listed in Table 8 were not detected in either unit. Table 8 lists the emission factors for PAH/SVOC. Emission factors range from 0.3 to 233 ng/MJ for Coal Creek, 0.5 to 273 ng/MJ for the Niles Boiler, and 0.3 to 130 ng/MJ for the SNOX process. Acetophenone is at the highest concentration of the PAH/SVOC in all three units. Naphthalene, dibenzofuran, phenanthrene, and fluoranthene are also present at relatively high concentrations in comparison to the other PAH/SVOC.
Date: May 1, 1994
Creator: Sverdrup, G. M.; Riggs, K. B.; Kelly, T. J.; Barrett, R. E.; Peltier, R. G. & Cooper, J. A.
Partner: UNT Libraries Government Documents Department