Stainless Steel Reflector Research Articles

Sonochemical reactor characterization in the presence of cylindrical and conical reflectors

Ultrasonic systems must be able to produce an acoustic field with the highest possible energy concentration in sonochemical reactors to accomplish maximum efficacy in the sonolytic degradation of water contaminants. In the present study, the impact of cylindrical and conical stainless-steel reflectors placed on the liquid surface on the sonochemical oxidation activity of ultrasonication reactors was investigated. The amount of effective acoustic power transferred to the ultrasonicated medium without and with reflectors was measured by calorimetric characterization of the sono-reactors at diverse ultrasonication frequencies in the interval of 300–800 kHz and different electrical powers in the range of 40–120 W. Iodide dosimetry without and with reflectors at diverse ultrasonication conditions (300–800 kHz and 40–120 W) and various aqueous solution volumes in the range of 300–500 mL was used to assess the sonochemical oxidation activity, i.e., the generation of oxidative species (mainly hydroxyl radicals). Sonochemiluminescence (SCL) imaging was used to study the active acoustic cavitation bubbles distribution in the sono-reactors without and with reflectors. Significant impacts of the position and shape of the reflectors on the active acoustic cavitation bubble distribution and the sonochemical oxidation activity were observed due to remarkable modifications of the ultrasonic field by directing and focusing of the ultrasonic waves. A significant augmentation in the triiodide formation rate was obtained in the presence of the conical reflector, especially at 630 kHz and 120 W (60.5% improvement), while iodide oxidation was quenched in the presence of the cylindrical reflector at all ultrasonication frequencies and powers. The SCL images show a noteworthy modification in the ultrasonic field and the acoustic cavitation bubble population when reflectors were used. The sonochemical oxidation activity was improved by the conical reflector when placed in the Fresnel zone (near field region).

DETERMINATION OF THERMAL EFFICIENCY AND COOKING POWER OF PARABOLIC SOLAR CONCENTRATING SYSTEM WITH THERMAL COMPENSATOR FOR DOMESTIC APPLICATIONS

Energy and the environment have a strong relationship. The production and consumption of energy is one of the biggest causes of environmental damage on earth. Therefore, the rapid increase in the level of CO2 and other greenhouse gases are given out during burning fossil fuel rise or unsteady of fuel prices are the main purposes led to a search to more effectively utilize a different sources of renewable energy. To reduce the consequences of greenhouse gases emitted by burning fuel for energy, which course depletion of the ozone layer and global warming. Therefore, the use of solar radiation directly as a source of energy has proved in the past to be less economical and affordable. The paper was aimed at determination of the performance of a parabolic solar concentrating system with a thermal compensator for domestic applications using thermal efficiency and cooking power. The parabolic dish solar collector (PDSC) with a focal point of 6.15 m, aperture area of 5.8 m2 and rim angle (φo) of 45O was designed and constructed for the determination of the variables. The PDSC was made of stainless steel reflector sheet in such a way that both the manufacturing and assembly method do not require complicated skilled techniques and cost. Since the PDSC is for high temperature steam generation, hot water and cooking application. A finite element stress test analysis was conducted to determine the thermal efficiency and cooking power of the system under various weather conditions. A simple manual solar tracking mechanism was employed, and the results of the system performance were also reported. The efficiency according to thefinding depends on the optical properties of the materials involved, the geometry of the collector, and the various imperfections arising from the construction of the collector. The thermal efficiency and cooking power of the system were determined and obtained to be 54.4% and 543.1W respectively.

PERFORMANCE EVALUATION OF PARABOLIC CONCENTRATOR WITH THERMAL STORAGE SYSTEM FOR DOMESTIC APPLICATIONS

Solar energy is a free natural resource but its harvesting requires a high capital investment whichprohibits its maximum exploitation. A Parabolic Dish Solar Collector (PDSC) with a thermalstorage system was been constructed and developed to harness solar beam radiation. The thermalstorage system and PDSC were constructed using locally and less cost materials such asgalvanized metal sheet and steel rods curved to obey the equation of a parabola then weldedtogether with circular support rings which was then lined with stainless steel reflector pasted forthe construction of PDSC. The receiver was made of blackened aluminium material incorporatedwith coiled copper tube carrying water as the heat transfer fluid. A parabolic dish which acts of aheat collector is used to track and reflects solar radiation at a single point (focus) on a receiverabsorber. Heat transfer from the solar collector to the storage tank was done by usingthermosyphonic principle to circulate the water (heat transfer fluid) between storage tank andheating system (receiver). The evaluation of thermal storage and analyzing the efficiency oftracking and non-tracking parabolic dish solar collector was carried out during month of June,2020 for the composite climate of Sokoto. According to the finding, the efficiency of trackingPDSC with thermal storage system and non- tracking PDSC with thermal storage tank weredetermined and obtained to be 52.9% and 50% respectively.Keywords: thermal efficiency, parabolic dish collector, solar radiation, storage system andstainless steel reflector.

Performance Evaluation of Spiral Coil Receiver for Thermal Steam Generation Using Optical and Thermal Analysis of Parabolic Dish Concentrator

Solar energy has been advocated as the substitute for depleting fossil fuels for thermal applications and electricity generation. The research was aimed at determining the performance evaluation of the spiral coil receiver for thermal steam generation using a parabolic concentrating system. The parabolic dish solar concentrator (PDSC) with a rim angle of450C, the focal length of 6.15 m, and an aperture area of 5.8 m2 were designed and constructed for the determination of the variables. The PDSC and spiral coil receiver were made of stainless-steel reflector sheet and copper tube pipe respectively. Since the PDSC is for high enthalpy steam generation, it can be used for hot water and cooking applications. A finite element stress analysis was carried out to determine the thermal and optical efficiency of the system under various weather conditions. The thermal efficiency and optical analysis of the system were determined and obtained to be 54.4%, and 48.6% respectively. The efficiency according to the finding depends on the optical properties of the materials involved, the geometry of the collector, and the various imperfections arising from the construction of the collector.

Neutronic simulation of the CEFR experiments with the nodal diffusion code system RAST-F

CEFR is a small core-size sodium-cooled fast reactor (SFR) using high enrichment fuel with stainless-steel reflectors, which brings a significant challenge to the deterministic methodologies due to the strong spectral effect. The neutronic simulation of the start-up experiments conducted at the CEFR have been performed with a deterministic code system RAST-F, which is based on the two-step approach that couples a multi-group cross-section generation Monte-Carlo (MC) code and a multi-group nodal diffusion solver. The RAST-F results were compared against the measurement data. Moreover, the characteristic of neutron spectrum in the fuel rings, and adjacent reflectors was evaluated using different models for generation of accurate nuclear libraries. The numerical solution of RAST-F system was verified against the full core MC solution MCS at all control rods fully inserted and withdrawn states. A good agreement between RAST-F and MCS solutions was observed with less than 120 pcm discrepancies and 1.2% root-mean-square error in terms of keff and power distribution, respectively. Meanwhile, the RAST-F result agreed well with the experimental values within two-sigma of experimental uncertainty. The good agreement of these results indicating that RAST-F can be used to neutronic steady-state simulations for small core-size SFR, which was challenged to deterministic code system.

Performance analysis of photovoltaic module with reflector: Optimizing orientation with different tilt scenarios

For sites near the tropic of cancer, an efficient technique to artificially improve solar photovoltaic (PV) performance by integrating the commercial flat stainless-steel (SS) reflector is determined in this study. The present research work focuses on the structural importance of reflectors and proposes a novel method for extracting more power output with fewer efforts. The system's optimum tilt has been calculated for various reflector diameters (L_ratio = 1 to 6, W_ratio = 1 to 6). A 3-D model has been used for wavelength-based reflection analysis on an hourly basis. The length of the reflector should be limited by the interrow distance between PV strings, for which the system's optimal tilt must be determined. For the latitude range of 20°–30°N, the yearly optimal tilt of the PV module has been recorded in between 32° and 40° with reflector tilt 19°–13° for the same size reflector.The annual energy gain has been estimated as 18.35%, which improved up to 34.16% with reflector dimension for the Jaipur location (26°N). For effective reflector size, the gain increased as 28.31–31.33% for the latitude range 20–30°N. The study suggested that the two-time tilt adjustment in a year is sufficient for countable gain improvement, reducing complexity for an operative PV plant.

Frequency and power dependence of the sonochemical reaction

The dependence of the sonochemical reaction on ultrasonic intensity was studied over a wide frequency range of 22–1960 kHz and sample volume range of 25–200 mL. The effect of a stainless steel reflector set on the water surface was also considered. Experiments were carried out by direct ultrasonic irradiation of a sample in a vessel. The potassium iodide (KI) method was used to evaluate the sonochemical reaction in terms of efficiency and reaction rate, and calorimetry was used to determine ultrasonic power. A quenching phenomenon, where the reaction rate decreased despite an increasing ultrasonic power, was observed at all frequencies and sample volumes, which indicated the existence of a maximum reaction rate. The maximum reaction rate increased with the frequency, except at 1960 kHz, and with the sample volume. The ultrasonic power at which quenching occurred increased with the frequency and sample volume. Sudden quenching occurred without the reflector, whereas gradual quenching occurred with the reflector. Based on the results, ultrasonic power density (i.e., ultrasonic power divided by the sample volume) can be used to estimate the ultrasonic power at which quenching occurs for various sample volumes.

A detailed simulation-based study on the effect of mirror integration on PV Module(s) with analysis of different wind flow scheme

The effective use of the available land in a PV power plant can be obtained by the integration of a commonly available flat stainless-steel reflector. The integration of the reflector increases module temperature and simultaneously the degradation rate. In this regard, the present work proposes a 3-D opto-thermal simulation model to analysis the performance of the commercial C-Si PV module with stainless steel (SS) reflector. The study also highlights that the natural flow of wind effectively reduces the elevated temperature and the direction of wind flow plays a very prominent role in heat evacuation. Incidentally, the largest state of India, Rajasthan has plenty of promising light breeze throughout the year and that is to come from the mostly north or west direction.A simpler version of the proposed model was experimentally validated in the month of July in Jaipur, India. The simulation result shows that the reflector induces 30 °C to 40 °C increment in temperature in the PV module for laminar airflow. Considering the turbulent airflow model, the temperature rise is 10–20 °C. The thermal scenario largely depends on wind flow and the season considered. The lifetime of the PV module is reduced from 25 years to 21 years with the integration of reflector at favorable wind flow condition. However, it generates a significantly more electric power which overcomes the lifetime loss.

SENSITIVITY ANALYSIS OF STAINLESS STEEL REFLECTOR FOR VR-1 TRAINING REACTOR

Pressurized water reactors are typically surrounded in the radial direction by neutron reflectors made from stainless steel and water. These reflectors decrease neutron leakage and provide protection of pressure vessel from fast neutrons damaging its integrity. Such a radial reflector influences multiplication factor of the core and distribution of neutron flux and fission power inside the core. All these effects can be analyzed by full-core simulations using macroscopic constants. Methodology for generation of the macroscopic constants for non-fuel regions will be tested for new stainless steel reflectors at the VR-1 reactor. Rods from SS 304l material will be used for construction of radial reflectors for the VR-1 reactor. They will be design to generate sufficient measurable response in selected core characteristics. The study is focused on core power distribution and reactivity worth of absorbing rods in a VR-1 reactor core. The core typically consists of about 20 IRT-4M fuel assemblies and seven absorbing rods UR-70. Replacing water surrounding the core by several reflector assemblies containing stainless steel will influence leakage and distribution of neutrons inside the core. The current analysis deals with local effects and employs the sensitivity study to discover the nature of reflectors’ impact on the reactor core. These effects were studied even for several past VR-1 reactor core configurations. All calculations were carried out in Serpent2 Monte-Carlo code with various evaluated libraries: ENDF/B-VII.1, ENDF/B-VIII.0, and JEFF-3.3 data.

An Experimental and Mathematical investigation of optimal tilt angle and effects of reflectors on PV energy production

The performance of the solar photovoltaic panels relies on its direction and tilt angle with respect to the horizontal to obtain better conversion efficiency. The tilt angle of the PV panel needs to be in proper location and position to obtain maximum power output from photovoltaics. The optimum tilt angle is generally calculated based on global, diffused, and direct radiation on the horizontal surface. This study focuses on the concept of the optimal tilt angle that improves the performance of the PV panel. The paper discusses the MATLAB mathematical modelling and experimental validation conducted at Nitte, India to determine the optimal tilt angle of PV panels of the region for maximum solar radiation. The investigation also includes the effect of three different types of reflectors on the PV panel for the obtained optimal tilt angle. The experimental results show that to get the optimum power output, the tilt angle needs to be changed every month. Hence monthly optimal tilt must be chosen for optimum power output. The results showed a PV panel with a focused mirror reflector produced higher power output compared to aluminum and stainless-steel reflectors.

HIGH-PERFORMANCE MULTI-BATCH FUEL MANAGEMENTS FOR THE ADVANCED SOLUBLE-BORON-FREE ATOM CORE

The autonomous transportable on-demand reactor module (ATOM), a 450 MWth PWR-type small modular reactor (SMR), is under development at Korea Advanced Institute of Science and Technology (KAIST). The ATOM core is designed for soluble-boron-free and passive autonomous load-following operations by utilizing successfully an advanced reactivity control technology, centrally-shielded burnable absorber (CSBA). To enhance the ATOM core safety, CrAl-coated Zircaloy-4 is adopted as an accident-tolerant-fuel cladding. For a long operational cycle, the reference ATOM core has primarily accomplished with a single-batch fuel management (FM). In this paper, for more flexible operation and enhanced fuel utilization, various multi-batch FMs are investigated while the core performance is maintained in terms of both neutronic and safety aspects. These aspects are refueling pattern, cycle length, burnup reactivity swing, discharge burnup, axial and radial power peaking factor (PPF), total PPF, and temperature coefficients. Several refueling types are examined: In-out (low leakage), out-in (flattened power), and randomly scattered schemes. In addition, new heavy reflector designs, ZrO2 and PbO, are introduced instead of stainless steel reflector for an improved core performance. Moreover, a new CSBA loading pattern is also proposed for an effective reactivity control of multi-batch FM strategy. Numerical results show that with a two-batch FM the cycle length can achieve above 2 years with an average discharge burnup of 40 GWd/tU, while the burnup reactivity swing remains less than 1,200 pcm. On top of that, the coolant and fuel temperature coefficients are highly negative at the beginning of cycle and power profile is comparable to that with the single-batch FM. All calculations in these multi-physics assessments of the ATOM core are performed using a Monte Carlo-diffusion hybrid code system based on Monte Carlo Serpent 2 and nodal diffusion COREDAX codes.

Experimental analysis of parabolic trough collector system with multiple receiver geometries and reflective materials

Solar parabolic trough collector systems provide an attractive solution especially for solar thermal power generation. The performance of these systems significantly depends on receiver geometries. Therefore, in the current study, an experimental analysis has been performed using three different receiver geometries along-with two reflective materials. These receiver geometries include: simple tube (reference geometry A), receiver tube with straight absorber plate (geometry B), and receiver tube with curved absorber plate (geometry C), whereas, the reflective materials include: aluminum and stainless steel. The experimentation was performed under subtropical climate conditions of Taxila, Pakistan. From experimentation, it was identified that peak heat gain obtained from receiver geometries C and B were 71%, and 30% higher as compared to the reference geometry A, respectively. The, thermal efficiency of the system with geometry A was 20%, geometry B was 28%, and geometry C was 34%. Furthermore, two reflective materials i.e. aluminum and Stainless steel were used on geometry C which yielded best results for further parabolic trough collector performance analysis. It was observed that peak thermal efficiencies were 34.8% and 31% with aluminum and stainless steel as reflector materials. The results indicated that aluminum reflector was approximately 12% efficient as compared to stainless steel reflector. The results will help to cultivate the advantages of innovative receiver geometries and alternative reflective materials.

Designing Stainless Steel Reflector at VR-1 Training Reactor

Light-water reactor cores are commonly surrounded by a stainless steel and water reflector. The reflectors are improving power distribution in the core, reducing the leakage of neutrons and thus also protecting the pressurized vessel from the neutron irradiation and the following embrittlement. Contrary to the standard procedures utilized for generation of the fuel assembly data, the reflector elements require a special approach. The major difficulty with the reflectors is represented by an absence of neutron sources in the reflector elements. Some artificial neutron source simulating the realistic source of neutrons from neutron leakage from the surrounding fuel assemblies must be added in the calculation model. The reflector data in the full-core calculations have a great impact on the power distribution in the core. The research in this field is usually focused on the square geometry, and therefore the accurate data for the hexagonal geometry are lacking. Improvements in this area are needed. Training Reactor VR-1 is used for measurements related to nuclear engineering. Department of Nuclear Reactors operating this reactor at the Czech Technical University in Prague is currently designing reflector elements containing stainless steel in order to provide measurable characteristics that can be compared to calculations realized by either Monte-Carlo codes or macroscopic core simulators. This article summarizes the methodology of development of the reflector assemblies to improve their similarity with the VVER-1000 reflector. The impact of the evaluated nuclear data is assessed. Further improvements of the proposed design is necessary to reach better agreement with the neutron spectrum in VVER-1000 reactor reflectors. The influence of evaluated data on the global characteristics was found negligible.

Uncertainty propagation based on correlated sampling technique for nuclear data applications

A correlated sampling technique has been implemented to estimate the impact of cross section modifications on the neutron transport and in Monte Carlo simulations in one single calculation. This implementation has been coupled to a Total Monte Carlo approach which consists in propagating nuclear data uncertainties with random cross section files. The TMC-CS (Total Monte Carlo with Correlated Sampling) approach offers an interesting speed-up of the associated computation time. This methodology is detailed in this paper, together with two application cases to validate and illustrate the gain provided by this technique: the highly enriched uranium/iron metal core reflected by a stainless-steel reflector HMI-001 benchmark, and the PETALE experimental programme in the CROCUS zero-power light water reactor.

Neutron reflector analysis for the beam-port of the Missouri S&T Reactor

A preliminary neutron reflector material selection and feasibility study of an inexpensive reflector replacement for the neutron beam-port at the 200 kW Missouri University of Science and Technology Research Reactor (MSTR) was conducted using Monte-Carlo techniques. The Monte-Carlo N-Particle transport code (MCNP6.1) was used to model the neutron beam-port of the Missouri S&T Reactor in order to study the effects of adding different reflector materials, in terms of the neutron flux reaching the radiography/tomography facility in front of MSTR’s neutron beam-port. Aluminum, beryllium, titanium, nickel, nickel-58, lead, bismuth, tungsten and stainless steel reflectors were modeled to find the best neutron reflector for the beam-port. After examining reflector materials, it was concluded that none of them were an improvement over the current design. Experimental thermal flux was measured to be 1.0 × 107 ± 3.16 × 103 cm−2 s−1 at the exit of beam port for current version of beam-port. The current ratio of beam port inlet and outlet obtained from simulations was found to be 3.37 × 104. The flux of beam port inlet was determined on the order of 1.0 × 1011 cm−2 s−1 which is consistent with previous findings.

Validation of SuperMC code by simulating a Metal-cooled fast reactor – BFS-62-3A

Appraising the credibility and competency of a computer simulation can be done by verification and validation procedure. This study has been performed to validate SuperMC for precise simulation of metal-cooled fast reactors using a high profile heterogeneous critical core, the BFS-62-3A. This critical assembly – being attractive because of its multi-zoned structure with MOX fuel, high axial and radial heterogeneity, diversity of materials and their compositions, and eligibility/feasibility to benchmark the experiments and calculations – is a full scale mock-up of BN-600 hybrid core with different fuel regions and stainless steel reflector. Modeling of complex core design, calculation of desired parameters, and visualization of the complete model were all performed using SuperMC. The deviations of less than 0.4% and 0.8% appeared in the calculated values of multiplication factor and spectral indices respectively while average discrepancies for radial fission rate distributions in the fuel region and control rod worths were found to be 2.7% and less than 5% respectively that showed a good agreement of the simulation results with benchmark’s measured data. Present work thus validated SuperMC’s capability to precisely model a complex heterogeneous reactor core and to accurately calculate various neutron physics parameters that ultimately rendered a high level of confidence on its use in fast-spectrum and MOX-fueled nuclear fission reactors.

Experimental validation of mathematical models of identical aluminum and stainless steel engineered conical solar collectors

This paper studies the mathematical modeling of a conical solar collector (CSC) based on different reflector materials and view angles. The optical performance testing using both stainless steel reflector (SSR) and aluminum mirror reflector (AMR) was performed under similar conditions at reflector view angles of 35°, 40°, and 45°, respectively. Main operational parameters related to the thermal/optical efficiencies of the SSR and AMR systems were determined and compared with each other. In addition, the interdependent transient temperature responses of both system components were predicted using Matlab® ordinary differential equation (ODE) solvers. For the purpose of model validation, simulation results from both systems were compared with experimental data. Results showed that the highest efficiencies and maximum water temperatures were achieved at reflector view angle of 45°, but these values were significantly higher in AMR system than SSR system for all of the aforementioned cases.

Microstructural characterization and density change of 304 stainless steel reflector blocks after long-term irradiation in EBR-II

While thin reactor structural components such as cladding and ducts do not experience significant gradients in dpa rate, gamma heating rate, temperature or stress, thick components can develop strong local variations in void swelling and irradiation creep in response to gradients in these variables. In this study we conducted microstructural investigations by transmission electron microscopy of two 52 mm thick 304-type stainless steel hex-blocks irradiated for 12 years in the EBR-II reactor with accumulated doses ranging from ∼0.4 to 33 dpa. Spatial variations in the populations of voids, precipitates, Frank loops and dislocation lines have been determined for 304 stainless steel sections exposed to different temperatures, different dpa levels and at different dpa rates, demonstrating the existence of spatial gradients in the resulting void swelling. The microstructural measurements compare very well with complementary density change measurements regarding void swelling gradients in the 304 stainless steel hex-block components.The TEM studies revealed that the original cold-worked-state microstructure of the unirradiated blocks was completely erased by irradiation, replaced by high densities of interstitial Frank loops, voids and carbide precipitates at both the lowest and highest doses. At large dose levels the amount of volumetric void swelling correlated directly with the gamma heating gradient-related temperature increase (e.g. for 28 dpa, ∼2% swelling at 418 °C and ∼2.9% swelling at 448 °C). Under approximately iso-thermal local conditions, volumetric void swelling was found to increase with dose level (e.g. ∼0.2% swelling at 0.4 dpa, ∼0.5% swelling at 4 dpa and ∼2% swelling at 28 dpa). Carbide precipitate formation levels were found to be relatively independent of both dpa level and temperature and induced a measurable densification. Void swelling was dominant at the higher dose levels and caused measurable decreases in density. Void swelling at the lowest doses was larger than might be expected based on the dpa level, an observation in agreement with earlier studies showing that the onset of void swelling is accelerated by decreasing dpa rates.

High sensitivity imaging of resin-rich regions in graphite/epoxy laminates using joint entropy

The continuing difficulty of detecting critical flaws in advanced materials requires novel approaches that enhance sensitivity to defects that might impact performance. This study compares different approaches for imaging a near-surface resin-rich defect in a thin graphite/epoxy plate using backscattered ultrasound. The specimen, having a resin-rich void immediately below the top surface ply, was scanned with a 1 in. dia., 5 MHz center frequency, and 4 in. focal length transducer. A computer controlled apparatus comprised of an x-y-z motion controller, a digitizer (LeCroy 9400A), and an ultrasonic pulser/receiver (Panametrics 5800) was used to acquire data on a 100 ×100 grid of points covering a 3 × 3 in. square. At each grid point 256 512-word, 8-bit backscattered waveforms, were digitized, signal averaged, and then stored on computer for off-line analysis. The same backscattered waveforms were used to produce peak-to-peak, signal energy, as well as entropy images. All of the entropy images exhibit better border delineation and defect contrast than the either peak-to-peak or signal energy. The best results are obtained using the joint entropy of the backscattered waveforms with a reference function. Two different references are examined: a reflection from a stainless steel reflector, and an approximate optimum obtained from an iterative parametric search. The joint entropy images produced using the optimum reference exhibit ~3 times the contrast obtained in previous studies.

Entropy based detection of molecularly targeted nanoparticle ultrasound contrast agents in tumors

In this study, we demonstrate the use of “joint entropy” of two random variables (X,Y) can be applied to markedly improve tumor conspicuity (where X = f(t) =backscattered waveform and Y = g(t) = a reference waveform; both differentiable functions). Previous studies have shown that a good initial choice of reference is a reflection of the original insonifying pulse taken from a stainless-steel reflector. Using this choice, joint entropy analysis is more sensitive to accumulation of targeted contrast agents than conventional gray-scale or signal energy analysis by roughly a factor of 2[Hughes, M. S., et al., J. Acoust. Soc. Am., 133(1), p 283, 2013]. We now derive an improved reference that is applied to three groups of (MDA-435, breast tumor) flank tumor-implanted athymic nude mice to identify tumor vasculature after binding perfluorocarbon nanoparticles (~250 nm) to neovascular avb3 integrins. Five mice received i.v.avb3-targeted nanoparticles, five received nontargeted nanoparticles, and five received saline at a dose of 1 ml/kg, which was allowed to circulate for up to two hours prior to imaging. Three analogous groups of nonimplanted mice were imaged in the same region following the same imaging protocol. Our results indicate an improvement in contrast by a factor of 2.5 over previously published results. Thus, judicious selection of the reference waveform is critical to improving contrast-to-noise in tumor environments when attempting to detect targeted nanostructures for molecular imaging of sparse features.