bluuebunny/crossref_metadata_2025 huggingface dataset:
Variability in Residential Air Leakage
Authors: Sherman MH , Wilson DJ , Kiel DE
Published: December 2008

Air leakage is the single most important quantity in the determination of air infiltration in residential structures. Air leakage is most commonly measured using the fan pressurization technique [ASTM Method for Determining Air Leakage Rate by Fan Pressurization Test (E 779-81)]; the data gathered with this method are often used to determine a leakage constant and a flow exponent. In this report, data gathered from the literature are compiled into a list of leakage constants and flow exponents, and the variability of these values over climate and housing types are examined.
Natural and Mechanical Ventilation in Tight Swedish Homes—Measurements and Modelling
Authors: Blomsterberg 0A , Lundin L
Published: December 2008

Air infiltration, an important energy loss mechanism in buildings, has been studied in a number of tight homes in Sweden. Two methods of measurement have been used: the fan pressurization technique was used for measuring the airtightness of the building envelope and the tracer gas technique was used for measuring the natural and mechanical ventilation. An automated air infiltration measurement system was developed. The system works on the principle of keeping a constant concentration of a tracer gas. Pressurization is used routinely for checking dwellings in Sweden. This technique does not give the air infiltration as a direct result.

A previously developed model correlating airtightness and air infiltration was used for evaluating the performance of the tested houses. The original model was developed at Lawrence Berkeley Laboratory for American homes and has now been modified for Swedish homes.

The results show that it is difficult to model air infiltration, and that it is difficult to achieve the recommended minimum ventilation rate as given in the Swedish Building Code if you are to rely only on natural ventilation in a tight home. Most new Swedish homes meet the airtightness requirement of the Swedish Building Code and are equipped with mechanical ventilation.

The paper presents results from measurements in Swedish homes using the tracer gas technique and the pressurization technique. The techniques are described. The results from the measurements are compared with predictions using a model correlating airtightness and air infiltration.
Analysis of Air Change Rates in Swedish Residential Buildings
Authors: Boman CA , Lyberg MD
Published: December 2008

Measurements of the rate of air exchange in residential buildings have been carried out by the Swedish Institute for Building Research since 1970. The results of an analysis of these measurements are presented in this paper for about 500 buildings not having mechanical ventilation.

The studied buildings include one- and two-story, detached, single-family houses, row houses, and multifamily residential buildings built between 1900 and 1982 and of various design. In some cases, the buildings have been retrofitted by improving the insulation of the attic or the exterior walls. The building sites vary from freely exposed to a sheltered urban environment.

Tracer gas measurements using the decay technique have been used for the determination of the rate of air exchange. In about 300 cases, the measurement of air change rates has been complemented by measurements using pressurization techniques. Data on 50 other parameters also have been collected. These parameters describe the building geometry, the building design, and the meteorological conditions at the time of measurement. The measurements have been performed with the outdoor temperature varying from −15 to +25°C and for wind speeds from 0 to 10 m/s.

The calculation model used for the analysis includes two dimensionless variables and two parameters. The dependent variable is given by the measured air change rate and the geometric properties of the building, while the other variable is defined as the ratio of the aeromotive force to the buoyancy force. The two parameters of the model represent the degree of wind shelter and the leakage area of the building, respectively.

For the analysis, the buildings have been divided into classes according to the building environment, the year of construction, and the type of building.
Influence of Mold Coverage upon the Notch Strength of R25 Sheet Molding Compounds
Authors: Shirrell CD , Onachuk MG
Published: December 2008

The influence of a processing variable, mold coverage, upon two 25% by weight randomly oriented 2.54-cm-long glass fiber reinforced sheet molding compounds (R25 SMCs) was examined. Artificially created flaws, in the form of machined circular notches, were utilized to determine the effect of mold coverage upon the naturally occurring tensile flaw sites in these materials. The critical hole size (that size circular notch through which all specimens fail) was found to be 9.53 mm. Variations in mold coverage from 97.5 to 25% were observed to have virtually no effect upon this critical hole size. Thus, the most severe tensile critical flaw sites in R25 SMC appear to be unrelated to mold coverage. A comparison of the two R25 SMC's indicates that a rubber toughening agent reduces slightly the notch sensitivity of isophthalic polyester resin matrix sheet mold compounds. Within experimental error, the two-parameter notch strength model of Whitney-Nuismer was found to accurately describe the notch sensitivity of R25 SMC.
Interface Studies of Aluminum Metal Matrix Composites
Authors: Fu L-J , Schmerling M , Marcus HL
Published: December 2008

In both continuous- and discontinuous-fiber aluminum metal matrix composites (MMC) the interface plays a major role in fracture. The interface chemistry and crystallography of both graphite/aluminum continuous-fiber and silicon carbide/aluminum (SiC/Al) discontinuous-fiber MMCs were observed on ion beam thinned specimens in the transmission electron microscope (TEM). The fracture mode and fracture surface chemistry of SiC/Al MMCs were investigated with the scanning electron microscope (SEM) and Auger electron spectroscopy (AES) combined with inert ion sputtering. The materials investigated were representative of the discontinuous-fiber SiC/Al composite (ARCO, SILAG) and the particulate SiC/Al composites (DWA) at the time of the study.

The TEM results show that an oxide is present at some of the SiC/Al interfaces, often in the form of γ-Al2O3 (along with MgAl2O4 when the aluminum matrix contains magnesium). The fracture path is not dominated by the interfacial failure but is primarily a matrix failure path. The more ductile the matrix, the less interfacial fracture. The large volume fraction of silicon carbide plays a major role in the fracture behavior by influencing the localized volume of material being deformed. Some of the fracture energy may have been reduced due to prior formation of dislocation networks due to thermal coefficient of expansion mismatch between the silicon carbide and the aluminum matrices. These networks were not apparent in the particulate SiC/Al MMC.

Both fine-grained γ-Al2O3 and small amounts of coarse-grained Al4C3 were found in the interfaces of the as-received graphite/aluminum composite specimens. During heat treatment, some of the Al4C3 phase grows into and along the graphite fiber surface.
Fatigue Behavior of Continuous-Fiber Silicon Carbide/Aluminum Composites
Authors: Johnson WS , Wallis RR
Published: December 2008

Four layups of continuous-fiber silicon carbide (SCS2) fiber/aluminum matrix composites were tested to assess fatigue mechanisms, including stiffness loss, when cycled below their respective fatigue limits. The layups were [0]8, [02/±45]s, [0/90]2s, and [0/±45/90]s. The data were compared with predictions from the first author's previously published shakedown model which predicts fatigue-induced stiffness loss in metal matrix composites. A fifth layup, [±45]2s, was tested to compare the shakedown and fatigue limits. The particular batch of silicon carbide fibers tested in this program had a somewhat lower modulus (340 GPa) than expected and displayed poor bonding to the aluminum matrix. Good agreement was obtained between the stiffness loss model and the test data. The fatigue damage below the fatigue limit was primarily in the form of matrix cracking. The fatigue limit corresponded to the laminate shakedown limit for the [±45]2s laminate.
Fatigue Damage in Notched Pultruded Composite Rods
Authors: Mallick PK , Little RE , Thomas J
Published: December 2008

The primary damage mode in a notched pultruded composite rod in rotating bending fatigue was found to be fiber-matrix debonding which originated at the notch root and extended along the length of the specimen. At stress amplitudes equal to or greater than 35% of the tensile strength of the material, debonding was followed by tensile rupture of the fibers at or near the notch, resulting in catastrophic failures of the specimens. At lower stress amplitudes, the slow growth in debonding resulted in a gradual increase in the dynamic deflection of the specimen. The static flexural stiffness ratio of a fatigue-damaged specimen to that of an undamaged specimen was found to be a reasonable measure of damage due to fiber-matrix debonding.
Damage Mechanisms and Accumulation in Graphite/Epoxy Laminates
Authors: Charewicz A , Daniel IM
Published: December 2008

Damage mechanisms and accumulation, and associated stiffness and residual strength reductions, were studied in cross-ply graphite/epoxy laminates under cyclic tensile loading. Stress-life data were fitted by straight lines on a log-log scale. The fatigue sensitivity decreases with the number of contiguous 90-deg plies. Five different damage mechanisms were observed: transverse matrix cracking, dispersed longitudinal cracking, localized longitudinal cracking, delaminations along transverse cracks, and local delaminations at the intersections of longitudinal and transverse cracks. Variations of residual modulus and residual strength were measured as a function of cyclic stress level and number of cycles. The residual modulus shows a sharp reduction initially, followed by a more gradual decrease up to failure. The residual strength showed some characteristic features: a sharp decrease initially then a near plateau in the middle part of the fatigue life, and a rapid decrease in the last part of the fatigue life. A cumulative damage model is proposed based on residual strength and the concept of equal damage curves.
Effect of Ply Thickness on Longitudinal Splitting and Delamination in Graphite/Epoxy Under Compressive Cyclic Load
Authors: Lagace PA , Nolet SC
Published: December 2008

The initiation and growth of damage due to compressive cyclic loading was investigated in [±45n/0n]s graphite/epoxy laminates where the “effective ply thickness” was varied by allowing n to take on the values 1, 2, and 3. A total of 35 axially loaded sandwich specimens with 6.35-mm-diameter holes were cycled at 7 Hz at peak stress levels of 52% to 72% of the static ultimate compressive stress of 425 MPa (which was experimentally determined to be independent of the value of n). Out-of-plane moiré interferometry and pulse-echo ultrasound techniques were used to nondestructively inspect the specimens and showed that three distinct modes of damage growth occur in these laminates. Delamination which initiates at the hole and grows in a radial or transverse fashion occurred only in 60% of the [±45/0]s specimens. For these two types of damage, the growth was rapid and led to catastrophic failure of the specimen. The remainder of the [±45/0]s specimens and all the laminates where the effective ply thickness was doubled and tripled, [±452/02]s and [±453/03]s, exhibited delaminations which initiated at the hole edges and grew parallel to the load direction with the width of the delamination equal to the width of the hole. Catastrophic failure did not occur in these cases. There is a linear relationship between the delamination length and the logarithm of the number of applied load cycles in all these cases. However, the delamination initiated earlier and at lower stress levels for laminates with larger effective ply thicknesses. Specimen sectioning and microscopic examination show that this damage depends on the development of splitting in the 0-deg plies and subsequent delamination as a result of shear failure at the −45°/0° ply interface in the region between the splits. Several [0/±45]s and [02/±452]s coupon specimens were cycled in tension and this splitting and subsequent delamination also developed. Residual tensile strength tests conducted on graphite/epoxy coupons debonded from the honeycomb after cycling showed a 50% increase in tensile strength over undamaged specimens with 6.35-mm-diameter holes. This is attributed to the redistribution of stress around the hole due to the relieving of stress concentration in the 0-deg plies by the splitting and delamination.
Influence of Sublaminate Cracks on the Tension Fatigue Behavior of a Graphite/Epoxy Laminate
Authors: Carlsson L , Eidefeldt C , Mohlin T
Published: December 2008

Quasi-isotropic 32-ply graphite/epoxy specimens were tested in static tension and tension fatigue. Both dry specimens and specimens containing 1% moisture (by weight) were tested. The first type of damage observed under both static and cyclic loading was transverse matrix cracking in the 90-deg plies. Under continued static or cyclic loading the cracks propagated into the neighboring −45-deg plies. No delamination was observed under static loading. In fatigue the matrix cracks acted as initiators of delamination, which resulted in a marked reduction in stiffness and residual strength. For specimens which had been subjected to a tensile overload before fatigue cycling, delamination occurred earlier due to the formation of more transverse matrix cracks.

The major effect of moisture was to increase the stress level at which first-ply failure occurred and to delay damage development during fatigue at low stress levels. The leveling-off of the crack density at an approximately constant level during fatigue loading gives support to damage models which predict the occurrence of a characteristic damage state, independent of load history, before laminate failure.
Masonry Cleaning—The State of the Art
Authors: Boyer DW
Published: December 2008

Development of safe and effective cleaning techniques for older masonry structures has been an objective of numerous contracting and manufacturing firms for many years. A wide variety of effective cleaning techniques have resulted from this development. Unfortunately, many applicators are unaware that cleaning agents and techniques that prove effective for application to some masonries may prove ineffective or too harsh for application to adjacent or dissimilar masonries.

Improper application of “proven” cleaning systems to stained masonry surfaces, without adequate pretesting and thorough evaluation of the masonry and staining conditions, has resulted in severe and often irreparable disfigurement and discoloration of scores of masonry buildings and monuments.

The intention of this paper is to review the variety of cleaning materials and techniques available to masonry cleaning contractors and building conservators. Emphasis is placed on chemical-assist, water washing techniques as they apply to the restorative cleaning of older, exterior masonry surfaces.

Illustrations of field and laboratory testing procedures required for development of cleaning programs to remove surface and subsurface staining — without damage to the masonry and surrounding nonmasonry surfaces — are presented.
Criteria for Selection of a Most Appropriate Cleaning Method
Authors: Jones LD
Published: December 2008

Historic preservation guidelines are becoming an increasingly larger factor in the commercial construction industry, thanks to the Economic Recovery Tax Act of 1981 and an emerging social attitude that older buildings have intrinsic value. In other words, historic preservation is going “mainstream,” and is no longer restricted to museums and other nonprofit applications.

The Secretary of the Interior's Standards for Historic Preservation state that “surface cleaning of structures shall be undertaken with the gentlest means possible. Sandblasting and other cleaning methods that will damage the historic building materials shall not be undertaken.” The guidelines for application of the standards make reference to the more detailed preservation briefs for additional guidance.

Preservation Brief No. 1, “The Cleaning and Waterproof Coating of Masonry Buildings,” discusses various cleaning methods, but without definitive conclusion. While the brief provides the reader with valuable information, there is still a need for further information in determining what constitutes “the gentlest means possible.”

It is the purpose of this paper to equip the reader with adequate information and a procedure for selecting the most appropriate cleaning method for a given project in terms of adherence to historic preservation standards. This will include an amplification on the role and merits of “water-safe” cleaning technology.

The principles described are exemplified in terms of specific projects undertaken by Clean-America, Inc., and are illustrated by means of photographs and data relating to specific details.
Chemical Cleaning of Historic Structures—A Practical Approach
Authors: Rudder TH
Published: December 2008

The aesthetic appeal of a building's facade is the visual vanguard of the entire building. Chemical cleaning of a building's exterior, if approached intelligently, can result in the building's substrate being returned to its original condition.

This paper outlines a step-by-step procedure that should be followed by the five key parties who share the responsibility for the cleaning of an historic structure. The duties and obligations of the building owner, the architect, the local preservation officer, the manufacturer of cleaning products, and the contractor are explored and some of the common pitfalls are explained.

The appendix includes a sample set of exterior building cleaning specifications.
Cleaning the Masonry Interiors of Public Buildings
Authors: Roth JW
Published: December 2008

Problems in the design, operation, and management of public buildings are discussed in the context of cleaning masonry in monumental and historic structures, particularly those subject to intense impacts by casual visitors. Design details, patterns of usage, cleaning standards, products, and procedures are considered. Information derives from architects' observations and assessments; from comments of operations staffs; and from construction specifications, custodial handbooks, and Historic Structure Reports. The paper concludes with a summary of illustrative examples and factors that determine the effectiveness of cleaning programs.
Cleaning and Waterproofing of Historic Masonry Buildings
Authors: Mack RC
Published: December 2008

This paper discusses the cleaning and water-repellent coating of historic masonry buildings from a generalist's point of view. Topics discussed include project planning, the three basic types of cleaning, testing cleaning procedures, and application of water-repellent coatings. A case study of the Minneapolis Grain Exchange Building summarizes the material.
The Role of Occupancy Analysis in Diagnosing Total Building Performance
Authors: Pleasantine D , Polly W , John Z
Published: December 2008

There is a crisis of premature building deterioration due, at least in part, to inadequate performance. This crisis has been particularly notable in office buildings. In addition, there are apparently conflicting demands in office environments: to reduce the energy consumption of buildings, to maintain or improve the productivity of employees accommodated, to satisfy their demands for a degree of environmental choice and control, and to respond to increased consumer awareness about the quality of such environmental attributes as air and lighting levels.

The approach taken in building diagnostics is highly innovative. In order to solve the complex problems being encountered, investigators have to diagnose buildings in transdisciplinary ways. This approach to problem solving requires that each disciplinary subgroup keep in mind a larger shared picture of the team's joint goals, that data are gathered concurrently and analyzed so as to test the findings and implications of decisions in each area, and that recommendations be examined that minimize negative side effects.

Occupancy analysis is one aspect of a transdisciplinary approach. It focuses on issues of environmental effectiveness, user well-being and control, and change (incremental and major) by probing patterns of, and attitudes towards, occupancy and use. This paper presents a case study in which this approach was applied. Occupancy analysis data, gathered with concurrent base technical testing of ambient environmental conditions, was used to focus more detailed technical testing in specific areas as necessary, thus reducing the enormous costs of blanket technical testing. Occupancy analysis provided critical data on perceived environmental comfort and effectiveness to be compared with the actual measurement of environmental conditions. The objective of this diagnostic project was to improve energy performance without diminishing environmental quality within office areas.

Increasingly it is being realized that unless all participants in building design, operation, and maintenance have an improved collective understanding of how to design and control the technical systems and layouts in buildings over time, new problems or negative side effects may be unintentionally created by unidisciplinary action. Diagnostic studies explore the possibility that improvement can be achieved by nurturing a sense of collective competence and well-being of occupants rather than the current sense of environmental deprivation, while minimizing operating and maintenance costs as well as building deterioration.
A Touring-Interview Method of Building Evaluation; the Place of Evaluation in Building Rehabilitation
Authors: Gray JM , Daish JR , Kernohan DQ
Published: December 2008

Accommodation options are to purpose build, to use ready-made, or to rehabilitate. The paper argues that rehabilitation is the option most likely to provide for good fit between organization and building. The procurement process must be one which allows management to link decisions about the organization with decisions about the building, taking account of differing interest groups. It is suggested that a participatory form of postoccupancy evaluation is a managable basis for initiating environment/behavior change. The paper gives a step-by-step description of a touring interview method of evaluation in current use in New Zealand and summarizes the lessons learned from efforts to institutionalize postoccupancy evaluation as a normal part of building procurement. The paper concludes with the suggestion that participatory evaluation has utility as a way to involve different interest groups in reaching negotiated agreement in programming for rehabilitation and as a basis for improved overall performance of buildings.
Developmental History of Institutions—Life History of Their Buildings
Authors: Peter J
Published: December 2008

This paper attempts to discuss mutual influences of the organizational development of institutions and their buildings. This is done in a dynamic approach in that the process of birth, growth, maturity, aging, and decay of institutions is described in its mutual impact on the life history of buildings from the briefing and design through realization, utilization, alteration, and rehabilitation to the physical decay and demolition or rebirth.

Building performance is not only a characteristic of the building itself but is highly determined by the dynamic process of development and transition which an institution undergoes during its existence.

So, even flexible and adaptable buildings show a deterministic, static character, and their total building performance must be permanently readjusted during the history of their use.

Building rehabilitation and preservation is seen as a means to support the organizational development of institutions in certain critical phases of their existence. The appreciation or condemnation of old buildings—as seen from institutional expectations and needs, from policy and value concepts, and from strategic and economic aspects—stems by no means only from functional or technological reasons.
Planning Standard Guidelines for Inspection and Evaluation of the Structural Condition of Existing Buildings
Authors: Stern EG
Published: December 2008

The guidelines for the inspection and evaluation of the structural condition of existing buildings provide information on how to approach the inspection and evaluation, what to look for during such an inspection, how to evaluate observations, and how to determine what actions should be taken and what procedures should be followed in improving a given situation in which the building is found. The guidelines are both materialand system-oriented, thus covering the materials commonly used in building construction and repair as well as the systems involved in the design and construction of the structural members, components, subassemblies, and unfinished as well as completed buildings.
A Method for Determining the Allowable Strength of In-Place Wood Structural Members
Authors: Jedrzejewski MJ
Published: December 2008

There are numerous older wood-structured buildings in the United States which have great potential for reuse; however, their allowable load capacity is unknown or is not readily calculable due to the lack of grade marks on the wood members which would identify their strength properties.

This paper describes a method by which the allowable strength properties of in-place wood structural members can be determined. The method consists of a series of procedures which utilize current ASTM standards and specific inspection techniques to render the allowable strength properties of the wood members. With the allowable strength properties of the wood members determined, the load capacity of the total structure, of specific members, or of areas of the structure can be determined by the use of common engineering calculations.
Evaluation of Building Deterioration by Water Runoff
Authors: Livingston RA
Published: December 2008

A significant cause of building deterioration is the erosion of surfaces through rainwater runoff, a process which can be accelerated by attack by air pollution, including acid rain. In order to make an accurate diagnosis of the problem, it is necessary to identify which agents of deterioration are present and to estimate the rate at which the material is being lost. This can be done rapidly and directly by measuring the amount of dissolved and suspended material removed in the water runoff and then calculating mass balances.

This paper proposes procedures for performing this type of measurement, including the apparatus required, the major variables and ions to be analyzed, and the interpretation of results. The general approach is to isolate a test area of the building surface so that the water flowing over it can be collected. The water can be either rainfall or distilled water sprayed on the building. If rainfall is the source of the runoff, samples of the incident runoff also must be collected to complete the mass balance. The collected sample is analyzed for concentrations of ions characteristic of the building materials under examination, such as aluminum, calcium, iron, and silicon. In addition, ions related to air pollution—such as sulfates and nitrates—are measured.
Overview of Studies in the United Kingdom on Neutron Irradiation Embrittlement of Pressure Vessel Steels
Authors: Davies LM , Ingham T
Published: December 2008

The paper describes work on irradiation embrittlement that has been undertaken in the United Kingdom since preparation of the Second Marshall Report on the Integrity of pressure water reactor (PWR) pressure vessels. Results from research programs concentrate specifically on work on steels for Magnox and PWR pressure vessel (PV) applications.

Models have been developed that describe the influence of copper precipitation on the yield stress changes in Magnox PV steels. Results from strength and microscopic examination confirm the significance of copper precipitation after long-term aging. The results provide support to the expression in the model to describe the time dependence of the copper precipitate contribution to the increase in yield strength.

Accelerated irradiation and surveillance data are present for both the Magnox and PWR PV steels. Modeling of data includes variations on neutron energy spectrum, neutron fluence, flux intensity, and irradiation temperature. The data for PWR PV materials have been used to examine the applicability of a recent draft revision of the U.S. Nuclear Regulatory Commission's Regulatory Guide 1.99 for estimating irradiation shifts on modern materials.

A study of mechanisms of embrittlement is reported including developments in positron annihilation studies and small-angle neutron scattering (both with and without the application of magnetic fields).
Irradiation Behavior of Reactor Pressure Vessel Steels from the Research Program on the Integrity of Components
Authors: Ahlf J , Bellmann D , Föhl J , Hebenbrock HD , Schmitt FJ , Spalthoff W
Published: December 2008

Within the research program “Integrity of Components,” reactor pressure vessel steels are irradiated in capsules in the swimming-pool-type research reactor FRG-2 at 290°C to different fluences of fast neutrons. Steel heats both conforming and not conforming to specifications with respect to chemical composition as well as to tensile and deformation properties are included.

So far, the results show that for the materials investigated the 41 J transition temperature shift from impact testing is always larger than the nil ductility transition (NDT) shift from drop-weight testing. This means that the mode of procedure of the regulatory rules leads to conservative values for the adjusted reference temperature even for material states near and beyond the specification limits.

From instrumentated Charpy tests, the arrest load was determined. It was found that the irradiation-induced shift of the arrest load versus temperature curve corresponds closely to the NDT shift. By evaluating Charpy surveillance specimens along this line, one has a supplementary criterion for assessing irradiation embrittlement at hand.

At low fluences, the 41 J transition temperature shifts are conservatively predicted by the trend curves of Regulatory Guide 1.99, whereas at high fluences—though a little beyond the validity limits—these shifts lie above the extrapolated trend curves.
Effect of Irradiation on the Elasto-Plastic Toughness of Pressure Vessel Steels
Authors: Petrequin P , Mundheri MA , Soulat P
Published: December 2008

A study on the effect of irradiation on the toughness of pressure vessel materials in the ductile regime has been undertaken. Compact tension (CT) specimens of two pressure vessel steels (A533 B and A508 Class 3) and a weld material of fitting chemical composition were irradiated and received neutron fluences of 3 and 8 × 1019 n/cm2. The J-R curves of these materials were determined between 100 and 290°C. Only a very small influence of irradiation was observed for tests at 290°C. In irradiated condition, the effect of the test temperature is not noticeable. At lower temperature, but in the ductile regime, the weld material appears to be more sensitive to neutron irradiation than the two steels. The forged material exhibited a surprisingly high shift of transition temperature since cleavage rupture occurred up to 100°C.

A method using tension tests on round notched specimens with different root radii was employed to obtain an alternative value of Jc. This method relates the Jc value to a critical growth of cavities that is determined from the tension test on notched specimens. A good agreement between this method and the conventional one was obtained for the A533 B steel. For the forged material, the results were more questionable and this was attributed to inhomogeneities in the distribution on nonmetallic inclusions for this material. This method is expected to be very useful for the determination of Jc for irradiated materials.
Investigations and Measures to Guarantee the Safety of a Pressurized Water Reactor's Pressure Vessel Against Brittle Fracture
Authors: Kaun UE , Koehring FKA
Published: December 2008

This paper presents the investigations and procedures being taken to guarantee the integrity of reactor pressure vessels (RPV) as a result of radiation embrittlement of the weld seam in the core region (22 NiMoCr 3 7 corresponding to ASTM A508, Class 2).

First, changes in the core map substantially reduced radiation exposure rates for the vessel wall. Second, experimental radiation programs on specimens and measured fracture toughness, Kk, of the welding material, as a function of neutron flux, are discussed together with the theoretical and experimental determination of neutron flux. As the high-pressure injection system is modified to hot leg injection, a depressurized thermal shock produces the critical pressure and temperature transients, which covers all other thermo-hydraulic plant transients with respect to brittle fracture loads.

Additionally, analytical results for the initiation and arrest of circumferential cracks, warm prestress effects for the end-of-life (EOL) state of the RPV, and limited crack size investigations are discussed. Finally, plant inspection plans with respect to vessel wall radiation exposure and nondestructive testing are illustrated.
Reactor Pressure Vessel Structural Implications of Embrittlement to the Pressurized-Thermal-Shock Scenario
Authors: Iskander SK , Sauter AW , Föhl J
Published: December 2008

A deterministic fracture-mechanics parametric-type analysis of a generic pressurized-water reactor pressure vessel has been conducted for loading conditions imposed by a specific category of hypothetical pressurized-thermal-shock transients. The time in the life of the vessel for which the calculations were made corresponds to attainment of the limiting nil-ductility transition reference temperature specified by the U. S. Nuclear Regulatory Commission's pressurized thermal-shock-issue-related screening criteria.

The transients considered were characterized by a constant pressure and an exponential decay of the downcomer coolant temperature. The decay constant, the final temperature of the coolant, and the fluid-film heat-transfer coefficient were the variable parameters. A search was performed to determine the critical pressure corresponding to incipient crack initiation for a range of crack depths up to 20% of the wall thickness. Results indicate that the critical pressure is greater than the normal operating pressure, if the coolant final temperature is greater than 150°C.

The fracture mechanics model used in the study tends to be conservative in the sense that it ignores possible beneficial effects of warm prestressing and cladding.
Safety Standard KTA 3203: Monitoring Radiation Embrittlement of Reactor Pressure Vessels of Light-Water Reactors
Authors: Ernst K-R , Klausnitzer EN , Leitz C
Published: December 2008

The paper presents a survey of the recently published German safety standard on surveillance programs for light-water reactor pressure vessels. The Kerntechnischer Ausschuss (KTA) safety standard is based on the new design of reactor pressure vessels with limited end-of-life neutron fluence and optimized steel quality. The program and the specimens required are outlined. Provisions are made for possible extension of the program in the event that the results are not as expected. Furthermore, careful program planning and documentation is required.
Irradiation Embrittlement of Reactor Pressure Vessel Steels: Mechanisms, Models, and Data Correlations
Authors: Odette GR , Lucas GE
Published: December 2008

A model of irradiation embrittlement is described for predicting the 41-J Charpy V-notch temperature shifts (ΔT) as a function of metallurgical variables and neutron exposure conditions. This forecasting procedure combines semi-empirical physical models with statistical analyses of test and power reactor data, and calibration against data from fundamental experiments in which both mechanical property and microstructural changes are evaluated. The models are based on the evolution of a damage microstructure, which includes both copper precipitates and a radiation damage component enhanced by nickel. The precipitate volume is also increased by nickel and impurity phosphorus. Predicted hardening and shifts associated with these extended defects are based on empirically validated models. The model is able to self-consistently rationalize a wide array of microstructural and mechanical property data for commercial pressure vessel steels as well as model alloys.
A Comparison of Mixed Flask Culture and Standardized Laboratory Model Ecosystems for Toxicity Testing
Authors: Shannon LJ , Harrass MC , Yount JD , Walbridge CT
Published: December 2008

Two microecosystem protocols, the standardized aquatic microcosm (SAM) method developed by Dr. Frieda Taub and associates (1982) and the mixed flask culture (MFC) method of Dr. John Leffler (1981), were compared on the basis of their responses to copper sulfate. These protocols differed in microcosm structure, age, and the variables monitored.

Two complete experiments were conducted with each method so that repeatability, as well as sensitivity and variability, could be evaluated. Copper caused significant reductions in pH, oxygen gain, and oxygen loss at concentrations down to 500 μg/L (the lowest test concentration) in the SAM tests and 320 μg/L in the MFC tests. Lower copper concentrations (36 and 70 μg/L) in the MFC tests caused significant increases over control levels for several system-level variables.

Although responses were similar with both systems, the SAM procedure provided considerably more insight into the changes in population densities and nutrient cycling responsible for the observed ecosystem level changes. This additional information was not obtained without cost, however. The SAM protocol was much more labor intensive and required about six times more laboratory effort than did the MFC protocol.

The SAM systems, on the basis of their higher coefficients of variation (CV) and higher minimum detectable differences (MDD), appeared to be theoretically less able to demonstrate significant toxic effects. This higher variability was at least partially offset by scheduling toxicant addition during the more sensitive early stages of microcosm development, since the frequency with which statistically significant effects were observed at comparable treatment levels suggested no inherent difference in sensitivity between the two systems.

The SAM results were more consistent, with microcosms developing and responding to copper in a similar manner in both runs. In contrast, the microcosms in the MFC experiments showed major differences in both development and sensitivity between runs.

Both methods were found to have strengths and weaknesses. The SAM protocol was more repeatable and provided a much more complete picture of toxicant effects, but was extremely labor intensive. The MFC protocol lacked repeatability and provided no information to aid in interpreting ecosystem-level effects, but was capable of displaying sensitivity equal to that of the SAM procedure and required a comparatively small time investment. We believe a useful new microcosm protocol could be developed by incorporating some of the strengths of the SAM system into a mixed flask type system.
A Simple In-Stream Test of Laboratory Findings that NTA Protects Fish and Invertebrates Against Copper and Zinc
Authors: Sprague JB
Published: December 2008

The chelating agent NTA (nitrilotriacetic acid) eliminated acute lethality of zinc and copper during 4 days of experimental dosing in a small creek. Caged salmon died in 4 h in the “polluted” zone, where added metals were 4 to 7 times the lethal threshold, and dead wild eels were also found. Downstream, with equi-molar NTA added, caged fish survived without marked signs of stress, and normal behavior of a wild eel was noted.

Benthic invertebrates were much more tolerant of metals than anticipated, and subtle changes in the community could not be documented by the deliberately minimal design of the experiment (pairs of Surber samples before and after treatment). The only demonstrated change in numbers was the virtual disappearance of blackfly larvae in the polluted zone, with no change in the control and anti-polluted zones. Cluster analysis of benthic samples also suggested effectiveness of NTA; the two polluted samples were distinct from a grouping which contained all other samples (“clean,” “before,” and “anti-polluted”). No effects were demonstrated for diversity index, genera, or total numbers.

As a side-issue, the experiment demonstrated that immature stoneflies and caddisflies, but not blackflies, can survive for 4 days in concentrations of zinc and copper that are at least 4 times the lethal level for salmonid fish. The relative tolerances of other taxa were uncertain because of small sample size, high variance, and few replicates.
Effect of 3-Trifluoromethyl-4-Nitrophenol on the Structure and Function of Protozoan Communities Established on Artificial Substrates
Authors: McCormick PV , Pratt JR , Cairns J
Published: December 2008

The development of community level toxicity testing protocols would allow for the direct determination of toxicant effects on community level processes. Using protozoan communities colonized on artificial substrates for testing the effects of hazardous substances allows rapid testing in a minimal amount of space. These communities were used in (1) 48-h acute tests, (2) a 28-day static test, and (3) 10-day continuous flow tests to assess the usefulness of structural and functional indices in determining adverse effects of the lamprey larvicide 3-trifluoromethyl-4-nitrophenol (TFM). Acute tests used protozoan communities of differing ages and were relatively insensitive to the toxicant; the EC50 was 48.0 ppm. Static tests used protozoan colonization as an index of stress and showed a significant increase in Ŝeq and a significant decrease in G at low (0.1 ppm) TFM levels. A significant reduction occurred in ciliate species at 10 ppm. Continuous flow tests had high variability in colonization within treatments, and no significant concentration differences were detected. Functional group analyses showed no effect on community function, although higher trophic levels were reduced or absent at 10 ppm. Results support the use of multispecies tests in determining toxic effects on natural communities, while showing the need for continued work in this area to develop standardized, replicable testing procedures.
Structural and Functional Response of Natural Phytoplankton and Periphyton Communities to a Cationic Surfactant with Considerations on Environmental Fate
Authors: Lewis MA , Taylor MJ , Larson RJ
Published: December 2008

The effects of a cationic surfactant were evaluated in field experiments with natural algal assemblages to validate the laboratory toxicity data base. Response parameters monitored in studies of 3 h to 21 days duration included structural and functional community characteristics in addition to more standard growth measurements. Photosynthesis and community similarity were typically the more sensitive parameters and a diversity index the least sensitive. The median effective concentration (EC50) values based on photosynthetic activity ranged from 0.4 to 6.1 mg/L. Phytoplankton were first affected in situ between 0.03 and 1.99 mg/L, relative to an effect level between 0.21 and 0.96 mg/L for periphyton. Periphyton colonized and exposed in river water containing 25% effluent were first affected at 6.9 mg/L. A mean in-stream concentration of 0.25 mg/L had no adverse effect on the indigenous periphyton of a small Indiana stream based on comparison of three-week pre- and post-exposure community analysis. Rapid biodegradation was observed in the field experiments.

The field-derived effect concentrations were compared with those determined in standard laboratory toxicity tests for four cultured algal species. The laboratory first-effect and EC50 levels for these single species were typically lower. Overall, the multispecies tests proved valuable in providing perspective on the potential for an environmental impact from this surfactant that could not be demonstrated in the laboratory using current standard testing methodologies.
Comparison of Leachate Quality in Foundry Waste Landfills to Leach Test Abstracts
Authors: Ham RK , Boyle WC , Blaha FJ
Published: December 2008

The landfills for six ferrous foundries in Wisconsin were instrumented with suction lysimeters to sample leachate directly from the waste above the zone of saturation. All landfills disposed of only foundry process solid wastes had minimal known changes in processes and waste over the period of landfilling in the areas tested and were not located in ground water. The quality of leachate from the lysimeters was compared to the quality of leachate obtained by laboratory leach testing of the auger cuttings obtained during lysimeter installation and to leach tests performed on composite raw waste samples obtained directly from the foundries.

It is concluded that, even though the (EP) (acid) test was able to predict the presence or absence of a contaminant in landfill leachates over half of the time, the test was inaccurate, in some cases grossly inaccurate, in predicting the actual field concentrations. It is also concluded that the EP (water) test was basically equal to the EP (acid) test in being able to predict the presence of absence of a contaminant in landfill leachates.
Principles of Bioreclamation of Contaminated Ground Water and Leachates
Authors: Parkin GF , Calabria CR
Published: December 2008

Improper disposal of hazardous wastes has resulted in contamination of saturated and unsaturated subsurface materials (the soil/rock/ground-water system) and production of leachates. One of the least appreciated and least applied remedial treatment techniques for these contaminated materials is biological treatment. Such treatment can result in the destruction of hazardous contaminants and may be cheaper than other alternatives. Efficient bioreclamation can occur when a proper, uniform environment for the bacteria, adequate contact between the contaminated materials and the bacteria, and sufficient time to effect the degradation are provided. Maintaining the proper environment (aerobic, anaerobic, or both) includes making sure biodegradable organics are present in sufficient quantity, paying attention to microbial nutrition, keeping the pH in a suitable range, and ensuring that the bacteria can adapt to the presence of toxic substances. Selection of the bioreclamation technique to be used depends on the nature and concentration of the contaminants. The choices for above-ground treatment are suspended-growth and attached/entrapped-growth reactors. Attached/entrapped-growth systems have significant advantages for treating hazardous wastes. The three basic options for in-situ treatment are (1) enhancement of indigenous bacteria, (2) extraction-injection-recycle, and (3) creation of a biologically active barrier. Patience and an appreciation for the keys to efficient biological treatment are required to make these options work.
Use of Flexible Membrane Liners for Industrial and Hazardous Waste Disposal
Authors: Koerner RM
Published: December 2008

This paper presents an overview of synthetic liners, called flexible membrane liners (FMLs), as used in the containment of solid wastes and their leachates in landfills. Details of FML manufacturing and properties are presented. This is followed by methods to evaluate chemical compatibility, elements of FML design, and various construction details. A series of topics for further research and development concludes the paper.