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DOE OSTI2023

Survey of Aging and Monitoring Concerns for Cables and Splices Due to Cable Repair and Replacement

The purpose of this report is to survey aging and monitoring concerns for electrical cable splices in nuclear power plants (NPPs) in long term operation. As portions of existing electrical cable runs in nuclear are replaced over time due to localized events, the total number of splices in NPPs is expected to increase. Relative to cables, the body of knowledge regarding aging of splices and splices in combination with aging cables in nuclear service environments in long-term operations is low. A few reports have considered the aging of cable system components other than cables (Jacobus 1990; Nelson 1998; Villaran and Lofaro 2002), but the nuclear industry has two decades of operating experience since these were published to further enlighten this issue. Herein we discuss electrical cables and splices commonly found in U.S. nuclear power plants, their qualification in safety-related application, and methods for monitoring their health condition. Common environmental stresses that can give rise to cable and splice failure are discussed. The Nuclear Regulatory Commission (NRC) Licensee Event Reports (LER) database was used to identify documented issues of cable and splice failure. The trend in the resultant data over time is considered to see if failures are increasing as plants age. Observations and conclusions of this work include: 1. Cables and splices are highly reliable components. Occurrence rates for events of interest were low and nearly constant over the last 20 years. 2. Common-cause failure for evaluated cable events of interest was observed to primarily be associated with loose connections, which may manifest associated with workmanship issues, thermal cycling, and/or vibration. 3. Replacement of cables is more common than repair, leading to an increase in proportion of new generation cables in the plant over time. 4. Splices on degraded cables have been observed to be problematic. Due to aging NPP infrastructure, including electrical cables, it is expected that such issues will continue to increase. 5. Condition monitoring approaches, while shown to be fruitful for cables, have been shown to be insensitive to degradation of splice sleeves, which are critical to the continued performance of splices. Additional condition monitoring (CM) work is needed to evaluate methods which are sensitive to the degradation of splice components. 6. Extended Material Degradation Assessment (EMDA) knowledge gaps for electrical cables (Bernstein et al. 2014) have not been investigated for splices but may represent similar concerns such as for the accelerated aging process historically used in environmental qualification.

42 ENGINEERING↗

DOE OSTI2022

Cold Spray Additive Manufacturing For New Pipeline Fabrication In Live, Natural Gas Distribution Mains

ULC Technologies (ULC) and the Penn State University Applied Research Lab (PSU ARL) developed a process and approach for rehabilitating live, natural gas distribution pipelines using Cold Spray Additive Manufacturing (CSAM). Robotic inline fabrication of a new pipe will be performed inside a natural gas main without disrupting customers. The material studied was blended with stainless steel which offers corrosion resistance, high strength and compatibility with hydrogen to enable a robust pipeline system that is future proofed. Stainless steel coatings sprayed and tested in the lab showed excellent strength, ductility, and porosity values. ULC initially sought to use methane as the process gas for compatibility with the host pipe, but after evaluating the field and lab challenges, nitrogen was deemed to be more suitable. Early robotic concepts have been developed that indicate technical feasibility. While the technology development originally targeted natural gas distribution mains, market research showed a broader need. Spot repairs performed in natural gas transmission mains may be a more economical approach for reinforcing distribution and transmission mains compared with full pipe-in-pipe rehabilitation. Additive manufacturing offers custom programming, as well as high accuracy and precision. This means custom contours can be manufactured in situ, offering flexibility in the repair solution, such as fabricating internal full circumferential sleeves. The value of the repair can be high at difficult-to-reach locations and in pipes that need reinforcement before the injection of methane-hydrogen blends.

03 NATURAL GAS↗

DOE OSTI2025

Impacts of PV Module Connector Failures on Cost and Performance of Utility Scale Photovoltaic Systems

The reliability, cost and performance of electrical connectors are a concern in all types of electrical systems, and demands on connectors used on photovoltaic (PV) systems include that connectors maintain electrical conductivity and physical strength, endure ultraviolet sunlight and high ambient temperature, and resist moisture and chemical intrusion over a very long (>25 year) performance period. Connector failures increase operation and maintenance (O&M) costs and reduce plant production, but connector failure can also cause safety and liability problems, which are of greater concern. This work results from a three-year collaboration between Sandia National Laboratories (SNL), the Electric Power Research Institute (EPRI), and the National Renewable Energy Laboratory (NREL) and funded by the U.S. Department of Energy (DOE) Solar Energy Technology Office (SETO) under Agreements #39035 and #38531 "Connector Reliability Across the US Solar Sector." a multi-pronged investigation of PV connector health across the US (see https://energy.sandia.gov/pvconnectors/). This report presents derivation of a Techno-Economic Analysis (TEA) that models failure modes and frequencies (how often failure occurs), estimates O&M costs and lost production associated with connector failures, and then calculates the effect that PV module connectors can have on Levelized Cost of Energy (LCOE). The model is informed with initial data from quantitative assessment of failure rates, root causes and mechanisms, in-situ diagnostics and data collection, lab-based forensics, and interviews with PV connector manufacturers and plant operators. SNL conducted site inspections at multiple utility-scale sites in different climates and subjected field samples of new, used, and degraded connectors to visual and electrical characterization. EPRI conducted metallurgical analysis of the pin and sleeve conductors to study failure-induced morphological and compositional changes. There is in general a shortage of statistically valid data, but data from PVROM database maintained by SNL was sufficient to ascertain failure rates and lost production as well as provide qualitative insight in its curated maintenance records. This report details the structure of the mathematical model but the sources of data to inform the model will continue to evolve. Analysis of a 100 MW PV plant is provided as an example of the use of the model, with results indicating that connectors are responsible for Annualized O&M Costs of $\$$71,933/year; Annualized Unit O&M Costs of $\$$0.72/kW/year; that a Reserve Account of $\$$187,220 should be available to fund repairs related to connectors; that connectors add $\$$1,494,004 to the Net Present Value of the O&M Costs (project life); and that O&M related to connectors adds about $\$$0.00088/kWh to the Levelized Cost of Energy. The impact of this model is to provide a tool to make the US solar sector more robust by quantifying and monetizing the reliability risks to utility-scale PV systems posed by poorly installed, mismatched and/or poorly designed and manufactured connectors. The TEA provides a model incorporating failure statistics, O&M cost data, and lost production into a single figure of merit, informing decisions and enabling practitioners to optimize cost and performance trade-offs. Stakeholders include connector manufacturers, system designers and equipment specifiers, standards bodies, installers and O&M providers, investors and insurance underwriters. This report supports continued growth of PV predicated on assurances that properly installed and maintained PV system connectors are safe and reliable. The project team is proposing future work including accelerated testing of connectors and expanding the approach taken here to other PV system components, such as TEA for rapid shut-down devices.

14 SOLAR ENERGY↗

DOE OSTI2025

Status Update for the Bearing Test Article Design Development – FY2025

Argonne National Laboratory’s (ANL) Mechanism Engineering Test Loop (METL) team has completed the design of a new Bearing Test Article (BTA) to test mechanical bearings for sodium fast reactor (SFR) mechanism applications. Recognition of the need for further bearing testing arose due to failure of rolling element bearings during testing of components for in-vessel fuel handling machines (FHMs) conducted at ANL in the METL facility. While the initial concept of the BTA arose from a need for bearing testing for FHM applications, the BTA design is configurable to test bearings of various sizes, types, and materials submerged in liquid sodium. Requirements for loading, shaft speed, temperature, and bearing size range were chosen based on requirements for SFR fuel handling. Modular components in the test bearing housings and shaft sleeves allow the design to accommodate a wide range of bearing sizes without modification to the larger assembly. Loading will be applied with screw jacks on the air side of the test article that will be adjusted to apply radial, thrust, or combined loading conditions. Applied force will be measured by load cells in-line with the loading mechanisms. In FY25 we have completed the design of the test article that will be fabricated and undergo testing at the METL facility. Drawing packages for the fabrication of the test article have been drafted and are being reviewed to add part tolerances and we have started ordering off-the-shelf components. The report will summarize the development of the Bearing Test Article design starting with an overview of the entire test article, then a more detailed examination of the bearing test section, loading mechanisms, test article ports and seals, and support structures, including analysis that went into significant design choices.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2022

High-voltage push to mate electrical interconnect

A high-voltage self-aligning push to mate electrical interconnect device is provided. The electrical interconnect device includes a housing with a mating end and a receiving end. The interconnect also includes an insulator bushing configured to be affixed to the receiving end of the housing. The interconnect also includes a center pin disposed within the housing. The center pin extends from the mating end of the housing to the receiving end of the housing. The interconnect also includes a connector socket disposed within the insulator bushing and which is in electrical communication with the center pin. The interconnect also includes an alignment sleeve including a chamfered mating funnel defining a void configured to accept and surround the housing and at least a portion of insulator bushing.

Martinez, David K.↗

DOE OSTI2023

DESIGNING A PARTICLE FLOW CONTROL APPARATUS

Flow control within a particle-based Concentrated Solar Power (CSP) system is essential in determining the heat transfer coefficient, and therefore, the power generation capability of these systems. There are three areas where particle flow control is significant: the receivers, storage tanks, and particle-sCO2 heat exchangers. The focus of this paper is on designing a new mechanism to control the flow in the particle-sCO2 heat exchangers due to the simplicity and potential cost savings when compared to the other areas of interest. The goal is for this new design to have quicker response times in terms of particle flowrate than a slide gate or flow control valve, which are designs currently used. The design resembles that of a chuck mechanism within a drill where a rotation of the sleeve elicits movement of the jaws both vertically and horizontally to close the outlet area of the nozzle. Additionally, this design will utilize the current actuator that is already used within these heat exchangers to reduce the complexity of implementation. The jaws are designed to be closed at an angle of 76 ̊ which is just slightly steeper than the hopper leading to the mechanism. Furthermore, this design can be tuned to limit particle bridging and other particle flow phenomena that result in blockages. The prototypes were 3D printed out of polylactic acid (PLA) and scaled up to 100%, 200%, and 400% to be able to observe the velocity profiles of the mechanism more clearly. Experiments are performed with this prototype to compare the inlet and outlet mass flow rates at different configurations of the jaws. The particles used in these experiments are 0.3mm HSP 40/70 that are commonly used in particle-based CSP systems.

14 SOLAR ENERGY↗

DOE OSTI2023

Safety Related Concerns with Installation and Use of Switch-Rated Plug/Receptacle Combinations in Lieu of Metal-Enclosed Disconnect Switches

The manufacturers of Nationally Recognized Testing Laboratory (NRTL) listed, switch-rated, plug and receptacle combinations tout their convenience, reliability, efficiency, and compliance with both the National Fire Protection Association (NFPA) 70®, National Electric Code (NEC), and National Fire Protection Association 70E®, The Standard for Electrical Safety in the Workplace, as advantages to using these products in lieu of traditional metal-enclosed disconnect switches. The purpose of this paper is to raise awareness of several unintended consequences that can result when replacement involves high energy cord and plug connected equipment. This paper describes several possible issues in complying with the NFPA 70 Articles 110 and 400 and NFPA 70E Articles 110 and 130 that should be considered when using load rated plug/receptacle combinations. This paper is intended to address high energy circuits typically associated with 480 volt pin and sleeve type connections in applications where incident energy levels may exceed 1.2 calories/centimeter² (cal/cm²).

99 GENERAL AND MISCELLANEOUS↗

DOE OSTI2023

Magnetic self-mating fiber optic connector and fiber optic switch sensor

A system or method for a magnetic self-aligning coupling device for a fiber optic cable. The device includes a first end coupling comprising a first magnet and a second magnet. Both magnets include a mating surface and an annular ring defining an axial aperture. The aperture receives a distal end of a segment of fiber optic cable in a tight fit. The fiber optic cable has an exterior sleeve and a fiber core. The fiber core of the first segment and the second segment of the fiber optic cable are axially aligned by magnetic force in the first and second apertures to create a continuous fiber optic path. A method for detecting a security breach of a door using the self-aligning couplings is also described.

Neidigk, Stephen↗

DOE OSTI2023

Method for fabrication of sleeveless photonic crystal canes with an arbitrary shape

The fabrication of sleeveless canes utilizes a preform with an array of glass canes in the preform. At least one tube-sleeve encircles the array of glass canes and is secured to the array of glass canes. The array of glass canes is moved into a furnace wherein the array of glass canes is heated. The furnace is maintained at a furnace temperature within the range of 2000° C. to 1700° C. and the array of glass canes is drawn from the furnace. The drawing of the array of glass canes both scales down the glass canes and elongates the glass canes. Maintaining the furnace at a furnace temperature within the range of 2000° C. to 1700° C. assures that the array of glass canes and the glass canes maintain their original shape.

Drachenberg, Derrek Reginald↗

DOE OSTI2023

Changing Temperatures, Changing Risks

Imagine what life with dengue fever would be like in the U.S. during the year 2050. You live with your family in Houston, Texas, and enjoy frequent fishing excursions at the nearby nature reserve. On average, days are about 5° Fahrenheit warmer than in the previous decade, and a summer dengue outbreak is underway. The local public health agency recommends using insect repellent, wearing long sleeves and pants, covering strollers with mosquito netting, and installing screens on windows and doors. It also suggests eliminating mosquito habitats near homes by emptying water-holding containers like planters, toys, tires, and trash receptacles.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2024

UNCERTAINTIES FOR IN-REACTOR TESTING OF TRITIUM LOADED GETTERS WITH TEMPERATURE CONTROL

The fourth experiment in TPBAR Materials Irradiation Separate-Effects Test (TMIST) series (TMIST-4) is planned to experimentally determine the effect of neutron irradiation on the equilibrium vapor pressure of tritium over a tritium loaded Nickel-Plated Zirconium (NPZ) getter in a simulated TPBAR service environment. This pressure will be used to estimate the tritium permeation rate. In the thermal design in the TMIST-4, two evaluations are required. 1) The cladding temperature is calculated to estimate the feasibility of detecting potential irradiation enhancement of the partial pressure for an NPZ getter. This work is required to obtain a precise cladding temperature for measurement of a low tritium partial pressure. This work has been completed and indicated that the required/target cladding temperatures based on the TMIST-4 test plan can be satisfied under the test condition range by modifying the capsule component shapes and inserting a thermally conductive metal sleeve. 2) The evaluation of uncertainties associated with the test design and operation is performed. This includes fabrication tolerances, and power and nuclear operating conditions. These factors will impact the component temperatures inside capsules and resulting the tritium partial pressure. The tritium permeation rate is a function of temperature and tritium partial pressure. The prediction of tritium permeation rates affects the feasibility of obtaining measurement resolutions required to reach reasonable conclusion for potential irradiation enhanced performance. This work will investigate the uncertainties.

TTP, TPBAR, TMIST-4, TPBAR Materials Irradiation S↗

DOE OSTI2024

Magnetic self-mating fiber optic connector and fiber optic switch sensor

Neidigk, Stephen↗

DOE OSTI2022

Utah FORGE GeoThermOPTIMAL Video

This is a project description video by Dr. William W. Fleckenstein related to their "Development of Multi-Stage Fracturing System and Wellbore Tractor to Enable Zonal Isolation During Stimulation and EGS Operations in Horizontal Wellbores" R&D project at Utah FORGE which is linked bellow.

15 GEOTHERMAL ENERGY↗

DOE OSTI2023

Utah FORGE 2-2439: A Multi-Component Approach to Characterizing In-Situ Stress: Laboratory, Modeling and Field Measurement - Workshop Presentation

This is a presentation on A Multi-Component Approach to Characterizing In-Situ Stress at the U.S DOE FORGE EGS Site: Laboratory, Modeling and Field Measurement project by Battelle [Columbus, OH], presented by Mark Kelley. The project's objective was to characterize stress in the Utah FORGE EGS reservoir using three methods: a laboratory rock-core stress estimation combined with a Machine Learning approach for estimation of in-situ stress from field sonic-log data, a field based in-situ measurement (min-frac) approach, and a modeling approach. This presentation was featured in the Utah FORGE R&D Annual Workshop on September 7, 2023. The workshop provided a valuable opportunity to explore the progress made in each of the 17 Research and Development projects funded under Solicitation 2020-1 which aim to enhance our understanding of the crucial factors influencing the development of Enhanced Geothermal Systems (EGS) reservoirs and resources.

15 GEOTHERMAL ENERGY↗