Analysis and Measurement Services (United States)

Designing catalytic systems that overcome the intrinsic trade-off between activity and selectivity remains a fundamental challenge in selective alkyne hydrogenation. Here, we report a preconstruction strategy (PCS) to precisely assemble Pd2-Cu1 integrated clusters (ICs) stabilized by ionic liquids, achieving fully exposed active sites with 100% atomic utilization. This rational design enables nearly complete conversion of acetylene with >99% ethylene selectivity and durability over 800 h of continuous operation. Compared to conventional impregnation methods, the PCS ensures atomic-level control over the coordination environment and electronic structure, as validated by advanced spectroscopy and density functional theory calculations. The optimized C2H2/C2H4 adsorption behavior and the tailored hydrogenation pathway over Pd2-Cu1 ICs significantly lower the energy barriers for key intermediates while suppressing overhydrogenation. This work establishes a generalizable bottom-up design principle for constructing atom-efficient, stable, and selective hydrogenation catalysts, offering a transformative route for the development of next-generation heterogeneous catalysts.

This document addresses enduring challenges encountered in modern experimental modal analysis as well as earlier “resonance testing” associated with measured mode orthogonality requirements. To this end, the document’s goals are (1) retirement of false damping and real mode notions (dating back to Lord Rayleigh, 1877), (2) achievement a community consensus on 85+ years of resonance and modal testing, and (3) establishment of an experimental modal analysis process that is independent of a-priori predictive mathematical models. The above goals are satisfied by addressing six key objectives, namely (a) validation of measured complex experimental modes, (b) empirical isolation of experimental modes (the “Holy Grail” of resonance testing), (c) definition of a state-space orthogonality standard, independent of an approximate reduced-order mass matrix, (d) exploitation of state-space, left-hand eigenvectors and their relationship to modal momentum and kinetic energy distributions, (e) establishment of a universal practice for a broad family of modal testing methods, and (f) application of the above six objectives to ambient (operational modal analysis) methods.

In recent years, with the increasing demand for building energy efficiency and comfort in daily life, electrochromic smart windows have attracted widespread attention. Electrochromic smart windows utilize electrochromic material (ECM) technology to change the color or transparency of the window under the action of an electric field, thereby regulating the light and heat entering the room and achieving energy-saving effects. A bistable electrochromic material is a material that can switch between two color states and maintain one of these states without an external electric field. Although ECMs with bistable properties can significantly reduce energy consumption, current research on their application in smart windows is limited. Therefore, three conjugated extended viologen polymers with thiophene derivative bridges, PDV-MMA, PBV-MMA, and PTV-MMA, were designed and synthesized, and electrochromic devices (ECDs) were prepared. The introduction of thiophene derivatives not only prolongs the effective conjugated chain length of viologen, but also extends the electrochromic (EC) response to the near-infrared (NIR) region. In addition, by inserting different thiophene derivatives to separate the two pyridinium moieties, viologen polymers emit strong fluorescence that can be quenched by applying a negative voltage. The electrochromic device based on PDV-MMA material has fast response time (1.8 s), low turn-on voltage (-0.9 V), high color contrast (73.7%), high coloring efficiency (550 cm2/C), and cycling stability (3300 cycles). In addition, ECD based on PDV-MMA exhibits bistable characteristics, with only a 10% transmittance decay within 221 min, displaying clear patterns even after 20 h of power outage, and significantly reducing indoor temperature (7.0 °C) in simulated indoor environments. These characteristics make the application of electrochromic smart windows highly attractive in energy-efficient buildings. The study also demonstrated an intelligent window system driven by a solar cell (SC), further validating its feasibility in practical applications.

Over the past 70 years, the US aerospace community has maintained a standard for verification and validation of experimentally determined, real structural dynamic modes and mathematical models based on mass-weighted orthogonality criteria. This standard fundamentally contradicts observable physical aspects associated with the mechanical behavior of structures. Specifically, (a) energy dissipation (damping) forces are most often concentrated in joints, rather than nearly uniformly distributed throughout the structure; (b) structural modes are mathematically complex, yet often approximately real except when successive modal frequencies are closely spaced; and (c) complex structural modes, while often are approximately real, do not strictly satisfy mass-weighted orthogonality criteria. A bottom-up approach, based on the Simultaneous Frequency Domain Technique (SFD-2018), employs left-hand eigenvectors to (1) isolate individual complex measured modes and (2) guarantee mathematical orthogonality of complex measured modes (completely independent of a theoretical mass matrix and model expectations). In addition, (3) complex modes deduced from virtually all experimental modal analysis techniques are classified in terms of a complex mode index parameter that indicates each mode’s level of “complexity,” and (4) conventional experimental mode orthogonality and experimental-to-theoretical mode cross-orthogonality metrics are adapted via replacement of the transform operator with the Hermitian operator permitting direct employment of complex experimental modes. A welcome surprise, due to review of a specific real experimental mode approximation extends the useful life of established US aerospace community standards for verification and validation of modal test data and correlation and reconciliation of modal test results and mathematical model predictions.

The aging of electrical cables has been the subject of substantial research and development (R&D) projects performed by national and international laboratories, universities, and private organizations for many years. This R&D was conducted to develop guidance, equipment, and techniques to support aging management of in-service cables in industrial facilities such as nuclear power plants, research reactors, waste facilities, and fuel fabrication plants. Through these research efforts, condition monitoring technologies have been developed that can determine the severity of age-related degradation that occurs in industrial cables and insulation polymers during service. This paper summarizes the results of aging assessments that were performed for cables installed in two U.S. nuclear power plants, one a pressurized water reactor and one a boiling water reactor. These cables had been in service for over 40 years and during plant operation were exposed to harsh environmental conditions including elevated temperatures and radiation. For these assessments, a comprehensive series of measurements was performed to assess the aged condition of the cables. These cables came from different manufacturers, were manufactured in different years, and were constructed with a variety of jacket and insulation polymers including chloro-sulfonated polyethylene (CSPE), cross-linked polyethylene (XLPE)/cross-linked polyolefin (XLPO), neoprene, and ethylene propylene rubber (EPR). The goal of these assessments was to determine the current aged condition of the cable polymers and provide an estimate of how long the cable insulation materials could remain exposed to their in-service environmental conditions before reaching their end-of-life condition. Both nuclear power plants have received license renewals to extend their operation from 40 to 60 years, and the utilities need objective evidence to show that critical components such as cables will be able to function safely and reliably during the extended operating period. The results of these assessments showed that the cables exhibited different aged conditions depending on the type of polymers they were constructed with and the environment they were exposed to during service. Some of the cables and insulation polymers showed signs of significant age-related degradation and were estimated to have approximately 5 years of remaining service life. Other cables exhibited no signs of significant age-related degradation and were estimated to have 50 years or more of remaining service life. Using the results of these cable aging assessments, plant personnel were able to (1) determine the overall aged condition of cables and insulation polymers using objective test results, (2) identify aged or degraded cables before they caused operability issues, and (3) avoid unnecessary and costly replacement of cables that can continue to operate safely and reliably.

The high-temperature irradiation-resistant thermocouple is the only temperature probe proven to withstand the high-temperature (>1290°C), high-radiation (a fluence of up to ∼1 × 1021 n/cm2) environments of nuclear reactor fuel design testing and/or over-temperature accident conditions. This report describes the improved performance of a molybdenum and niobium thermocouple by utilizing a coaxial design (i.e., a single wire grounded to the outer sheath). This optimized high-temperature irradiation-resistant thermocouple features a simplified design yet allows for more robust individual components. The niobium and molybdenum thermoelements can be used interchangeably in either the sheath or wire, depending on the intended application. Via a plunge test in flowing water, the response time of the coaxial build of the high-temperature irradiation-resistant thermocouple was determined to be 30x faster than that of the comparable ungrounded type-K thermocouples, and 10x faster than the grounded type-K thermocouples and traditional ungrounded high-temperature irradiation-resistant thermocouples (i.e., two-wire configurations). Furthermore, by capitalizing on the coaxial design, a multi-core high-temperature irradiation-resistant probe with multiple “single-pole” wires along the length of the sheath was proven feasible. This multi-core, thermocouple design was dubbed a “demicouple.” The high-temperature irradiation-resistant demicouple is primarily applied during fuel experiments to record multiple fuel-pin centerline temperature measurements using a single compact sensor. Furthermore, the shared “common” leg between demicouple junctions reduces error propagation in secondary measurements such as temperature differentials.

Difficulties encountered in modal test planning and recent advances in experimental modal analysis of aerospace systems have resulted in a new paradigm for experimental modal analysis. The Simultaneous Frequency Domain (SFD) method, weighted complex linear least squares correlation methodology, and state space model left- and right- hand eigenvector properties combine to produce the following benefits that are independent of an explicit TAM mass matrix: (1) verification and validation of experimental modes via isolation of individual experimental modes, (2) automatic self- orthogonality of experimental modes, (3) test- FEM cross orthogonality, and (4) experimental complex mode kinetic energy distribution. The new approach directly employs complex experimental modes (rather than real mode approximations) and frees experimental data from a potentially flawed TAM mass matrix. A roadmap for incorporation of the new paradigm into NASA and USAF standards and continued progress are outlined in this paper.

All nuclear power plants (NPPs), and other types of industrial facilities, over time suffer from faults and operating issues in cable circuits, connectors, shielding, and end devices while in service. These types of issues occur in both low voltage (LV) and medium voltage (MV) circuits, and a wide range condition monitoring (CM) technologies have been developed to identify, locate, and quantify the severity of age-related degradation that occurs in these systems and components. In general, the degradation and failure mechanisms that occur in MV cable circuits can be significantly different than those that occur in low voltage (LV) cables. One of the primary concerns of MV cables installed in NPPs is moisture related degradation that can cause a buildup of localized electrical stresses in the cable insulation polymer. These electrical stresses can lead to the formation and growth of water trees and/or electrical trees in the insulation and cause partial discharges to occur in the cable polymer. Over time, these moisture related issues can cause degradation of the insulation material and/or cable failure. As NPPs and other industrial facilities age, identifying, locating, and quantifying degradation in systems important to safety, operation and production along with their associated cables is becoming a higher priority for long term reliability. This paper presents the results and findings of a cable condition assessment that was performed using laboratory CM techniques to assess the aged condition of six (6) 5 kV MV cable samples removed from service at an operating nuclear power plant. During operation, these six (6) samples and other sections of this cable were submerged in water, and after nearly forty years of service had noticeable signs of moisture intrusion into the cable (e.g. low insulation resistance measurements and swelling and blistering of the cable jacket). Based on the results of the laboratory condition assessment, the jacket and insulation materials of these cable samples are susceptible to moisture related degradation, which can lead to water/electrical tree formation and growth in the cable insulation. These types of issues lead to degradation of the electrical properties of the cable (e.g. decreasing insulation resistance) and can eventually cause cable failure.

Small modular reactors (SMRs) are factory-built transportable nuclear power plants (NPPs) that can generate up to 300 MWe and support new applications for nuclear energy such as hydrogen production, industrial heat generation, and water desalination. SMRs are poised for near-term deployment in the United States and offer improvements over existing NPPs such as passive safety features, greater plant site flexibility, reduced construction costs, load-following operations, and extended refueling cycles. However, in order to realize the benefits of SMRs, there are several challenges related to instrumentation and control (I&C) system components that must be addressed. The I&C systems of an SMR ensure its safe and efficient operation. I&C sensors measure process parameters such as temperature, pressure, level, flow, and neutron flux and provide input to the Reactor Protection System (RPS) to initiate a rapid shutdown if necessary. The performance of these safety-related I&C sensors and systems must be periodically verified to ensure they meet the plant technical specifications for accuracy and response time. In addition, the associated I&C cabling (which includes low-voltage cable assemblies for sensors, Control Rod Drive Mechanisms (CRDMs), and Rod Position Indication (RPI) Systems) is tested as part of normal plant maintenance activities or in support of aging management programs. Over time, exposure to harsh environmental conditions in the plant can result in degradation and failure of I&C sensors and cables. This is especially true for the I&C sensors and cables in SMRs which will be subjected to elevated temperatures, high radiation, and a vacuum atmosphere within the containment vessel during normal plant operation. These conditions lead to excessive Ohmic heating within the cables which further accelerates damage to the cable insulation material and results in premature failure. Frequent cable replacement due to premature degradation is not practical or economical for SMR plant owners. To combat these environmental stressors, the ampacity of the cable must be derated. However, there is limited experience to date with cable derating in vacuum, and no experience with cable derating in vacuum at high temperature and radiation. As a result, Analysis and Measurement Services Corporation (AMS) is conducting a study on several common NPP I&C cables to determine how various insulation materials perform at conditions that emulate those anticipated in the containment of an SMR. The on-going effort is funded under a research and development (R&D) grant awarded to AMS by the U.S. Department of Energy (DOE). In addition, AMS is partnering with the Oak Ridge National Laboratory (ORNL) to conduct specialized testing in support of this study under a separate initiative called the Gateway for Accelerated Innovation in Nuclear (GAIN). The goal of this R&D is to develop technical guidance and technologies to support initial startup and subsequent operation of SMRs through specialized testing services and condition monitoring technologies. Preliminary results of this R&D are provided in this paper. AMS will continue to investigate challenges associated with I&C systems for SMR applications in support of the timely deployment of the first U.S.-based SMR by the mid-2020s.