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Molten fluorides were initially developed for use in the nuclear industry as the high-temperature fluid fuel for the Molten Salt Reactor (MSR). The U.S. Department of Energy Office of Nuclear Energ...

We compute power-voltage, power-current, and causal definitions of the characteristic impedance of microstrip and coplanar-waveguide transmission lines on insulating and conducting silicon substrates, and compare to measurement.

This paper discusses the rationale for the development of tissue engineering and associated therapies and provides observations on the emerging developments in these areas.

It has been proposed that GaCl{sub 3} can be removed by direct volatilization from a Pu-Ga alloy that is dissolved in a molten chloride salt. Although pure GaCl{sub 3} is quite volatile (boiling point: 201 deg. C), the behavior of GaCl{sub 3} dissolved in chloride salts is quite different because of solution effects and is critically dependent upon the composition of the solvent salt (i.e., its Lewis acid/base character). In this technical note, the behavior of gallium in prototypical Lewis acid and Lewis base salts is contrasted. It is found that gallium volatility is suppressed in basic melts and promoted in acidic melts. These results have an important influence on the potential for simple gallium removal in molten salt systems.

This paper compares closed-form approximations for coplanar waveguide and microstrip transmission-line parameters to accurate measurements and full-wave calculations. We suggest improved approximations and demonstrate the limitations of our proposed and current approximations for the efficient simulation of digital interconnects.

We develop analytic expressions for the impulse response and kickout pulses of a simple sampling circuit that incorporate the nonlinear junction capacitance of the sampling diode. We examine the effects of both the time-varying junction capacitance and conductance on the impulse response and kickout pulses, and discuss their impact on the accuracy of the nose-to-nose calibration technique.

We develop a new causal power-normalized waveguide equivalent-circuit theory that, unlike its predecessors, results in network parameters usable in both the frequency and time domains in a broad class of waveguides. Enforcing simultaneity of the voltages, currents, and fields and a power normalization fixes all of the parameters of the new theory within a single normalization factor, including both the magnitude and phase of the characteristic impedance of the waveguide. Enforcing simultaneity also ensures that the theory's voltages and currents do not start before their excitation, and that the network parameters of passive devices are causal, a necessary condition for stable time-domain simulations.

We develop a procedure and metrics for comparing large-signal-network-analyzer calibrations. The metrics we develop provide a bound on differences between measurements obtained from large-signal-network-analyzer calibrations, as well as specific information on how the power, phase, and scattering-parameter portions of the calibrations differ.

This study addresses the physical-chemical processes that might naturally or inadvertently occur and that would lead to a separation of the poisoning nonfissionable actinides (232Th, 238U) from the fissionable ones (239Pu, 235U) by selective dissolution and redeposition over a prolonged storage of the waste. Of the various chemistries that were evaluated, carbonate complexation reaction is the most plausible means of achieving the separation of these actinides. Carbonate ions (formed by the dissolution and hydrolysis of atmospheric CO2) can selectively dissolve the actinide oxides through the formation of soluble carbonate complexes, which could result in the separation of poisoning actinides from the fissionable ones. The concentrations of these soluble carbonate species are dependent on the pH, temperature, and other ions; therefore, changes in any of these parameters over time—especially cyclic changes (daily or seasonal)—could cause a selective dissolution and redeposition of the more soluble species ...

This paper investigates a measurement method that characterizes lossy printed multiconductor transmission lines, its accuracy, the choice of measurement representations, and some simple approximations. We illustrate the method with measurements of a pair of lossy coupled asymmetric microstrip lines.

Continuous annular sorption is a recent innovation that uses a slowly rotating annular sorbent bed to continuously separate components as a function of angular position. The current application of this technology, continuous ion exchange (CIEx), utilizes eluent in a much more efficient manner than the previous chromatographic applications. The efficient recovery of semidilute levels (10−20 mM) of lanthanide mixtures by CIEx is demonstrated experimentally, and a mathematical model of the process is used to predict equipment performance. Results from batch shake tests and fixed-bed runs support the CIEx modeling effort and are useful separative benchmarks. The implications of the results for scaleup and economic evaluation are examined.

The project involved the survey and selective excavation of an area of field system adjoining the Romano-British ‘courtyard house’ settlement of Chysauster, near Penzance, Cornwall, supported by soil and pollen studies and by the extensive landscape surveys. The excavation had two main elements: study of the rectilinear field system and excavation of a Bronze Age funerary cairn incorporated in one of the field boundaries. The earliest field system, probably with origins in the 2nd millennium BC, was largely modified by a more irregular and strongly lynchetted field pattern, probably associated with more intensive Iron Age and Romano-British agriculture. There was also some medieval or post-medieval reuse and modification. The cairn pre-dated a boundary bank of one of the early fields and was the focus for a number of cremation burials. Six of these were accompanied by pots which, together with their radiocarbon dates, provide a significant group of the middle phase of the Trevisker variant of the British Food Urn ceramic tradition. Excavation of field boundaries showed evidence of long periods of modification and lynchet accumulation but lacked good artefactual or radiocarbon dating evidence. Soil and pollen analysis produced significant new evidence for this region, showing the former existence of a brown soil under open oak/hazel woodland, with some cereal cultivation taking place, prior to the construction of the Bronze Age cairn. Later cultivation techniques led to deterioration in soil status and to soil erosion. Some field boundaries may have been constructed at this time to conserve soil or as dumps for clearance stone. The changes, through deforestation, cultivation, and erosion influenced the plant communities in the nearby valley where pollen analysis of a peat section suggested three phases of human activity.

Urea and ammonia together comprised 34.3–37.8% of the total ninhydrin-positive compounds in the brain of various developmental stages of Campanotus floridanus . The most abundant free amino acids were alanine (15.3–16.1%), proline (8.8–10.4%), aspartate (7.1–7.5%), glutamate (6.2–7.2%) and serine (4.3–5.9%). GABA levels increased between the pupal (1–4.1%) and adult worker stages. Taurine levels increased from 3.9% in larval brains to 6.5% in major workers. Brain concentrations of biogenic amines (dopamine, octopamine, noradrenaline and serotonin) increased between larval and adult stages. The possible relationships between neurochemical parameters and age polytheism are discussed.

The performance of medical devices constructed of polymers is crucially dependent upon the stability of the material. The tissues of the body offer a surprisingly hostile environment and there are several features of their composition, including the presence of enzymes, free radicals, superoxides and peroxides, which influence the degradation. In most cases polymers are chosen on the basis of their apparent stability while there are some cases in which intentional degradation is an advantage. This paper addresses some of the compositional and structural features of the polymers and of the tissue variables which control this susceptibility.

The purpose of this study was to determine whether the fibrin sheath that develops around an intravenous silicone catheter influences catheter-related sepsis. A rat model with a central intravenous silione catheter was used. Staphylococcus aureus , dose 1 × 10 7 colony forming units (cfu), were injected via the tail vein, either immediately after catheter insertion (group 1, n=23) or after the catheter had been in situ for at least 7 days (group 2, n=22). Blood cultures were done on at 24 hours and 7 days. Animals were killed on day 7 and the catheter was removed for culture (Maki and broth) and scanning electronmicroscopy (SEM). The was no significant difference ( P > .05) between the number of positive blood cultures in groups 1 and 2 at 24 hours (16 v 9) and 7 days (12 v 6). In group 1 there were significantly more positive catheter cultures by both methods (23 v 16 in group 2; P P P = NS). On SEM a fibrinous sheath was identified on all catheters removed on day 7 but not on 5 catheters inserted and removed after 10 minutes. The findings of this study suggest that catheter infection is more likely to occur when bacteremia is introduced immediately following catheter implantation before a fibrinous sheath has developed, compared with delayed bacteremia in the presence of a fibrinous sheath, suggesting a protective role for the sheath.

The Lorentz reciprocity condition is applied to junctions composed or reciprocal media which connect uniform but otherwise arbitrary waveguides. An expression relating for forward and reverse transmission coefficients is derived and factored into two terms, the first involving the phase of the reference impedance in the guide and the second a new reciprocity factor. The usual condition equation the forward and reverse transmission coefficients is shown not to hold in the general case. Experimental evidence supporting the theoretical results is presented. >

Two issues concerning the accuracy of electrical characterizations of interconnect transmission lines, particularly in regard to a recently published paper (S.B. Goldberg et al., ibid., vol.14, pp.761-5, Dec. 191) are discussed. The error in the characteristic impedance may be reduced through an alternative approximation to the capacitance of the transmission line. Furthermore, measurements of both the propagation constant and characteristic impedance, the two primary parameters characterizing the line, may be improved by the use of a well-conditioned algorithm. >

This paper considers the development of a general part sequencing methodology which suits flexible systems. A flexible assembly cell configuration is conceptualized. The cell is characterized by a common buffer and a single flexible transfer device for inter-cell transfer activities. Since the time available for decision making on part sequencing is very short, a fast solution is required. A real-time computerized part sequencing system of modular structure is developed. The system comprises three functions: ENTER, ALLOCATE, and TRANSFER SEQUENCE. Each function is provided with various priority options to satisfy different company strategies. Computer simulation is used to compare alternative sequencing structures of the system developed, and to examine its effectiveness under different operating conditions with reference to cell performance and time response.

We report a statistically significant negative correlation between the concentration (and the deposition rate) of the cosmogenic radionuclide 10Be and δ18O (of Globigerinoides ruber) in the sediments deposited in the anoxic Orca Basin (OB) of the Gulf of Mexico during the past ∼20 ka. Possible causes for this finding consecutively include: (1) enrichment of 10Be in the soils/easily erodable crustal material which were discharged into the OB during the Late Wisconsin Interglacial; (2) introduction of significant amounts of 10Be into the oceans due to the melting of continental ice sheets resulting in the enrichment of the radionuclide in the sediments deposited during that time; and (3) generation of a focussing effect resulting in the 10Be enrichment of the OB sediment.

This paper is concerned with the mechanisms of adhesion of dental restorative materials to hard tooth substance and the development of coupling agents. The work is focused on a dentine bonding system based on a polymerizable monomer with a functional group that has the capability to react with the amino or hydroxy groups of the dentinal collagen. An aliphatic, low molecular weight, and polymerizable monomer with hydroxyalkyl groups has been investigated for this purpose. This material possesses the reactivity of a hydroxy group and a vinyl double bond. The hydroxyalkyl group is different in its behaviour from other alcoholic structures, and it may promote adhesion to structures with amino groups. It is concluded that bonding of restorative resins to dentine may be achieved by this dentine bonding material. The bond develops rapidly and is both strong and hydrolytically stable.

The Advanced High-Temperature Reactor (AHTR) is a novel reactor design that utilizes the graphite-matrix high-temperature fuel of helium-cooled reactors, but provides cooling with a high-temperature fluoride salt. For applications at temperatures greater than 900 C the AHTR is also referred to as a Liquid-Salt-Cooled Very High-Temperature Reactor (LS-VHTR). This report provides an assessment of candidate salts proposed as the primary coolant for the AHTR based upon a review of physical properties, nuclear properties, and chemical factors. The physical properties most relevant for coolant service were reviewed. Key chemical factors that influence material compatibility were also analyzed for the purpose of screening salt candidates. Some simple screening factors related to the nuclear properties of salts were also developed. The moderating ratio and neutron-absorption cross-section were compiled for each salt. The short-lived activation products, long-lived transmutation activity, and reactivity coefficients associated with various salt candidates were estimated using a computational model. Table A presents a summary of the properties of the candidate coolant salts. Certain factors in this table, such as melting point, vapor pressure, and nuclear properties, can be viewed as stand-alone parameters for screening candidates. Heat-transfer properties are considered as a group in Sect. 3 in order to evaluate the combined effects of various factors. In the course of this review, it became apparent that the state of the properties database was strong in some areas and weak in others. A qualitative map of the state of the database and predictive capabilities is given in Table B. It is apparent that the property of thermal conductivity has the greatest uncertainty and is the most difficult to measure. The database, with respect to heat capacity, can be improved with modern instruments and modest effort. In general, ''lighter'' (low-Z) salts tend to exhibit better heat transfer and nuclear performance metrics. Lighter salts also tend to have more favorable (larger) moderating ratios, and thus should have a more favorable coolant-voiding behavior in-core. Heavy (high-Z) salts tend to have lower heat capacities and thermal conductivities and more significant activation and transmutation products. However, all of the salts are relatively good heat-transfer agents. A detailed discussion of each property and the combination of properties that served as a heat-transfer metric is presented in the body of this report. In addition to neutronic metrics, such as moderating ratio and neutron absorption, the activation properties of the salts were investigated (Table C). Again, lighter salts tend to have more favorable activation properties compared to salts with high atomic-number constituents. A simple model for estimating the reactivity coefficients associated with a reduction of salt content in the core (voiding or thermal expansion) was also developed, and the primary parameters were investigated. It appears that reasonable design flexibility exists to select a safe combination of fuel-element design and salt coolant for most of the candidate salts. Materials compatibility is an overriding consideration for high-temperature reactors; therefore the question was posed whether any one of the candidate salts was inherently, or significantly, more corrosive than another. This is a very complex subject, and it was not possible to exclude any fluoride salts based on the corrosion database. The corrosion database clearly indicates superior container alloys, but the effect of salt identity is masked by many factors which are likely more important (impurities, redox condition) in the testing evidence than salt identity. Despite this uncertainty, some reasonable preferences can be recommended, and these are indicated in the conclusions. The reasoning to support these conclusions is established in the body of this report.

The authors examine modal cross power in electromagnetic transmission lines. They show that the cross powers of nearly degenerate modes may be large in quasi-TEM multiconductor transmission lines typical of modern electronic circuits at moderate and low microwave frequencies. The authors develop simple expressions to estimate the magnitude of these cross powers from the "power-normalized" conductor impedance and admittance matrices of the lines.

We review the basic principles of operation of electrical sampling oscilloscopes and describe circuit models developed to design, characterize, and help explain their operation. We survey common oscilloscope calibration schemes that correct for finite oscilloscope impulse response, distortion and jitter in the oscilloscope time base, and impedance mismatches.

In this paper, we compare the power-voltage, power-current, and causal definitions of the characteristic impedance of microstrip transmission lines on silicon substrates.

Undesirable resonant cavity modes of a metal package are shown to be damped effectively by placing a dielectric substrate coated with a resistive film in the cavity. Theoretical predictions are confirmed experimentally. The application of this technique to a hybrid phase shifter in which coupling to a resonant mode of the package degrades circuit performance is discussed. The undesirable interaction of the phase-shifting circuit and a resonant package mode is shown to be suppressed effectively by the introduction of the lossy film. >

The National Institute of Standards and Technology operates a number of research projects to advance measurement science and technology for the microelectronic industries. We report here on one component of the NIST program, the fundamental electrical characterization of electronic interconnections through accurate measurement. We have developed and continue to develop measurement techniques for fully calibrated time-domain network analysis, lossy transmission lines on silicon, coupled transmission lines, fully calibrated multiport network analysis, low dielectric constant thin-film materials, and at-speed test.

This paper assesses certain systematic high frequency measurement errors inherent in the procedures described in the JEDEC 123 guideline for measurement of electronic package inductance and capacitance model parameters.

This paper compares a simple quasi-TEM model for coplanar waveguide fabricated on moderately doped silicon substrates to measurement. While the coplanar waveguide currents and magnetic fields are unaffected by the substrate, a simple capacitive model can accurately account for the effects of the substrate.

We use a measurement method designed for coupled lines on highly conductive substrates to characterize identical asymmetric coupled lines fabricated on lossy silicon with and without a metallization plane beneath the two signal conductors. The study illustrates the important role of the return path in determining the electromagnetic coupling between the lines.

In this paper, we apply a measurement method designed for asymmetric coupled lines to determine the broadband propagation characteristics of symmetric coupled lines fabricated on a highly conductive silicon substrate. We show that the matrices of frequency-dependent propagation constants and characteristic impedances, as extracted from calibrated four-port S-parameter measurements, agree very well with data predicted by numerical calculations.

We measure and compare the electrical parasitics of contact pads of different designs fabricated on silicon integrated circuits and develop a strategy for reducing the parasitics. We used an on-wafer probe system calibrated with the multiline through-reflect-line (TRL) probe-tip calibration.

We develop a numerical method of determining the magnitude of characteristic impedance required by causal power-normalized circuit theories from its phase using a Hilbert-transform relationship. We also estimate the uncertainty in the method.

It has been proposed that GaCl{sub 3} can be removed by direct volatilization from a Pu-Ga alloy that is dissolved in a molten chloride salt. Although pure GaCl{sub 3} is quite volatile (boiling point, 201 C), the behavior of GaCl{sub 3} dissolved in chloride salts is different due to solution effects and is critically dependent on the composition of the solvent salt (i.e., its Lewis-acid/base character). In this report, the behavior of gallium in prototypical Lewis-acid and Lewis-base salts is compared. It was found that gallium volatility is suppressed in basic melts and enhanced in acidic melts. The implications of these results on the potential for simple gallium removal in molten salt systems are significant.

Publisher Summary This chapter outlines the history of the Baikal drilling project and describes the main results of this project. The aim of this project is to study the paleoclimate in Central Asia through a comprehensive study of Lake Baikal sediment. A drilling rig that operates in an environmentally friendly manner is specially manufactured for this project. This rig is capable of drilling a sediment core of up to 1000 m at a depth of 900 m below the lake surface. The sedimentation pattern of the samples is dependent on the climate and topographical features of the area. Dense terrigenous clays formed during cold glacial periods, while sediments containing large amounts of diatom fossils were deposited during the interglacial periods. This alternating sediment pattern is typical of underwater uplifts that are isolated from the lakeshore by deep basins. A significant amount of sedimentation in the deep basins arises from turbidite flows, which also brings a large amount of fossilized vegetation. Gas hydrates, which were collected in fresh water also form in the deep basins. A continuous 5 Ma paleoclimatic record is obtained from the Academician Ridge, which correlates well with the oceanic oxygen curve. The paleoclimate of Central Asia is reconstructed by using the distribution of diatoms and biogenic silica content. The Lake Baikal paleoclimatic record is continuous and well dated and can be regarded as an excellent source of information on the paleoclimatology of continental interiors. As a result of investigations on the continuous Baikal record and its accurate dating, the age of several global events influencing Central Asia, the Eurasian continent, and the northern hemisphere have been more precisely dated.

A fundamental characteristic of the room temperature Molten Salt Reactor Experiment (MSRE) fuel is that the radiation from the retained fission products and actinides interacts with this fluoride salt to produce fluorine gas. The purpose of this investigation was to identify fluorine-trapping materials for the MSRE fuel salt that can meet both the requirement of interim storage in a sealed (gastight) container and the vented condition required for disposal at the Waste Isolation Pilot Plant (WIPP). Sealed containers will be needed for interim storage because of the large radon source that remains even in fuel salt stripped of its uranium content. An experimental program was undertaken to identify the most promising candidates for efficient trapping of the radiolytic fluorine generated by the MSRE fuel salt. Because of the desire to avoid pressurizing the closed storage containers, an agent that traps fluorine without the generation of gaseous products was sought.

Objective: The purpose of this study was to measure the cuspal deflection that occurs in teeth as a result of the dimensional changes of resin-based lutes during polymerisation. Methods: Standardised MOD cavities were cut in 15 intact human premolar teeth using a custom paralleling device. A ceramic inlay was machined by the CEREC 2 system for each tooth ensuring an interface width of 50 μm (SD=17.5) at the cavity margin. The 15 teeth were divided into three groups of five according to the cementation system employed: a microfilled hybrid posterior composite; a compomer restorative; a dual-cure luteing composite. The inter-cuspal tooth dimension was recorded continuously with a laser micrometer assembly during a 2 min photoactivation period and a further 30 min post-activation period. Results: A clear overall reduction in tooth dimension was detectable for the first 10 min of polymerisation. The mean changes ranged from −0.02% to −0.06% depending on the nature of the luting material. In addition, all samples exhibited a slight expansion of 0.03% during the time of light-activation. Conclusions: The dimensional changes that teeth experience during the polymerisation of resin-based lutes are clearly detectable. It can be postulated that an increase in the dimensions of the teeth during photoactivation occurs as a result of expansion of the lute due to the thermal energy delivered.

The Molten Salt Reactor Experiment (MSRE), at the Oak Ridge National Laboratory has been shut down since 1969 when the fuel salt was drained from the core into two Hastelloy N tanks at the reactor site. In 1995, a multiyear project was launched to remediate the potentially hazardous conditions generated by the movement of fissile material and reactive gases from the storage tanks into the piping system and an auxiliary charcoal bed (ACB). The top 12 in. of the ACB is known by gamma scan and thermal analysis to contain about 2.6 kg U-233. According to the laboratory tests, a few feet of fluorinated charcoal are believed to extend beyond the uranium front. The remainder of the ACB should consist of unreacted charcoal. Fluorinated charcoal, when subjected to rapid heating, can decompose generating gaseous products. Under confined conditions, the sudden exothermic decomposition can produce high temperatures and pressures of near-explosive characteristics. Since it will be necessary to drill and tap the ACB to allow installation of piping and instrumentation for remediation and recovery activities, it is necessary to chemically convert the reactive fluorinated charcoal into a more stable material. Ammonia can be administered to the ACB as a volatile denaturingmore » agent that results in the conversion of the C{sub x}F to carbon and ammonium fluoride, NH{sub 4}F. The charcoal laden with NH{sub 4}F can then be heated without risking any sudden decomposition. The only consequence of heating the treated material will be the volatilization of NH{sub 4}F as a mixture of NH{sub 3} and HF, which would primarily recombine as NH{sub 4}F on surfaces below 200 C. The planned scheme for the ACB denaturing is to flow diluted ammonia gas in steps of increasing NH{sub 3} concentration, 2% to 50%, followed by the injection of pure ammonia. This report summarizes the planned passivation treatment scheme to stabilize the ACB and remove the potential hazards. It also includes basic information, results of laboratory tests, thermodynamic calculations, process description, and operational parameters, and addresses safety concerns.« less

The Molten Salt Reactor Experiment (MSRE) at Oak Ridge National Laboratory has been shut down since December 1969, at which time the molten salt mixture of LiF-BeF{sub 2}-ZrF{sub 4}-{sup 233}UF{sub 4} (64.5-30.3-5.0-0.13 mol%) was transferred to fuel salt drain tanks for storage. In the late 1980s, increased radiation in one of the gas lines from the drain tank was attributed to {sup 233}UF{sub 6}. In 1994 two gas samples were withdraw (from a gas line in the Vent House connecting to the drain tanks) and analyzed. Surprisingly, 350 mm Hg of F{sub 2}, 70 mm Hg of UF{sub 6}, and smaller amounts of other gases were found in both of the samples. To remote this gas from above the drain tanks and all of the associated piping, the reactive gas removal system (RGRS) was designed. This report details the laboratory testing of the RGRS, using natural uranium, prior to its implementation at the MSRE facility. The testing was performed to ensure that the equipment functioned properly and was sufficient to perform the task while minimizing exposure to personnel. In addition, the laboratory work provided the research and development effort necessary to maximize the performance of the system. Throughout this work technicians and staff who were to be involved in RGRS operation at the MSRE site worked directly with the research staff in completing the laboratory testing phase. Consequently, at the end of the laboratory work, the personnel who were to be involved in the actual operations had acquired all of the training and experience necessary to continue with the process of reactive gas removal.

Experimental trials were conducted to investigate some unresolved issues regarding the use of chlorine trifluoride (ClF{sub 3}) for removal of uranium-bearing deposits in the Molten Salt Reactor Experiment (MSRE) off-gas system. The safety and effectiveness of operation of the fixed-bed trapping system for removal of reactive gases were the primary focus. The chief uncertainty concerns the fate of chlorine in the system and the potential for forming explosive chlorine oxides (primarily chlorine dioxide) in the trapping operation. Tests at the MSRE Reactive Gas Removal System reference conditions and at conditions of low ClF{sub 3} flow showed that only very minor quantities of reactive halogen oxides were produced before column breakthrough. Somewhat larger quantities accompanied breakthrough. A separation test that exposed irradiated MSRE simulant salt to ClF{sub 3} confirmed the expectation that the salt is basically inert for brief exposures to ClF{sub 3} at room temperature.

During FY 1995 considerable progress was made toward gaining a better understanding of the chemistry and transport processes that continue to govern the behavior of the Molten Salt Reactor Experiment (MSRE). As measurements in the MSRE proceed, laboratory studies continue, and better analyses are available, our understanding of the state of the MSRE and the best path toward remediation improves. Because of the immediate concern about the deposit in the auxiliary charcoal bed (ACB), laboratory studies in the past year focused on carbon-fluorine chemistry. Secondary efforts were directed toward investigation of gas generation from MSRE salts by both radiolytic and nonradiolytic pathways. In addition to the laboratory studies, field measurements at the MSRE provided the basis for estimating the inventory of uranium and fluorine in the ACB. Analysis of both temperature and radiation measurements provided independent and consistent estimates of about 2.6 kg of uranium deposited in the top of the ACB. Further analysis efforts included a refinement in the estimates of the fuel- salt source term, the deposited decay energy, and the projected rate of radiolytic gas generation. This report also provides the background material necessary to explain new developments and to review areas of particular interest. The detailed history of the MSRE is extensively documented and is cited where appropriate. This work is also intended to update and complement the more recent MSRE assessment reports.

The production of large quantities of high-specific-activity [sup 63]Ni (>10 Ci/g) requires both a highly enriched [sup 62]Ni target and a long irradiation period at high neutron flux. Trace impurities in the nickel and associated target materials are also activated and account for a significant fraction of the discharged activity and essentially all of the gamma activity. While most of these undesirable activation products can be removed as chloride complexes during anion exchange, chromium, present at [sup 51]Cr, and scandium, present as [sup 46]Sc, are exceptions and require additional processing to achieve the desired purity. Optimized flowsheets are discussed based upon the current development and production experience.

Adult forms of Schistosoma mansoni ingest host (human) red blood cells (RBCs). To elucidate potential mechanisms by which contact with adult parasites perturbs RBC membranes, we studied the effects of the membrane fraction of isolated schistosomes on RBC shape, volume, potassium ion content, and phospholipid and transmembrane protein lateral mobility. S. mansoni-treated RBCs exhibited rapid but spontaneously reversible shape change from discocytes to spheroechinocytes, reversible decrease in cell volume, and rapid loss of intracellular potassium ions. Treated RBCs also showed rapid but spontaneously reversible immobilization of membrane phospholipids and of band 3, the major transmembrane protein. These data suggest that components of adult S. mansoni membranes can perturb host RBC volume and membrane organization. In the absence of RBC lysis, RBC metabolic and repair mechanisms can reverse these effects.