Safety issues in nuclear power plants are of extreme importance. Numerous sensors are used within nuclear power plants for sensing and monitoring of its critical operation parameters. As currently implemented, during massive losses of power across the plant in accidents, the backup batteries for the monitoring sensors will ultimately be drained and can cease to operate. The overall objective of this NEUP project is to develop a novel self-powered wireless hybrid sensor which can accurately monitor both pressure and temperature using a single device, even in the extreme harsh environments of severe nuclear accidents, without the requirement of external electricity. At Virginia Tech side, a heat pipe assisted thermoelectric generator (TEG) energy harvester and associated power management and data transmission circuits were developed. The energy harvester can produce electrical power continuously, even in loss of plant and external power situations, providing power for important data transmission for accident diagnosis. The self-powered sensing system could be integrated directly onto key nuclear components including pipes, pump housings, heat exchangers, reactor vessels, and shielding structures inside and outside of the reactor core. Two TEG based energy harvesters which can work in relatively low (50-250 ºC) and high temperature ranges (250-350 ºC) were established and tested. In the prototypes, heat pipes were introduced to reduce the heat resistances of the device at the hot and cold ends. The power output of the heat pipe assisted TEG module is 2.22 W, which is 6 times more than one using an aluminum rod. In-lab tests showed that these devices canmeet the requirement to power the sensors and circuit during normal and off-normal conditions.Amodel was then built to analyze the thermal network in the energy harvester, and was used to optimize its performance and reduce its geometry size. The design and testing of the vibrational energy harvester were completed. The harvester, has shown to effectively increase the vibrational potential of the main coolant pump, though it has been shown that thermal energy has a much higher potential for the powering of sensors. In this project, a self-start charger circuit for the energy harvester was designed to regulate and manage the power. An energy storage element was incorporated into the energy harvesting module for sensors and wireless transceivers in an off-normal situation. The signal conditioning and wireless communication electronic circuits were developed and tested in the lab. An important consideration for an energy harvester within a nuclear power plant is the level of radiation it will encounter during operation. The two main sources of radiation in a nuclear power plant are gamma and neutron radiation. Aradiation experiment was conducted in the Westinghouse Electric Company during which the prototypes were placed in a 106 rad radiation environment to test their ability to operate in the extreme environment. The results showed that this level of radiation had little effect on the performance of the TEGmaterial and heat pipe heat exchanging system. Its influence on the circuit was still under research, however the need for more development on radiation hardened electronics is needed. Pressure measurement based on piezoelectric crystal resonators has advantages over the commercially available methods like capacitive, electromagnetic, optical, potentiometric, and piezo resistive strain gauges. Since the output of piezoelectric based sensors are digital in format, it has a very high resolution, high accuracy, and long-term stability. Quartz is one of the commonly used piezoelectric material in digital pressure sensors design. This material is elastic in nature, providing high stability, high repeatability, high elasticity, repeatable mechanical behavior for many cycles of operation, and is free of hysteresis. The quartz resonator has a high Q, which means that very high vibration can be driven with the very low electric power. Langasite (LGS) is a new promising piezoelectric material that combines the advantageous properties of quartz with a better performance at high temperatures. LGS will not undergo any phase transitions up to its melting temperature of 1473 C, and hence, the application of Langasite in measuring pressure at high temperatures is promising. In this project, the design and fabrication of the piezo oscillator crystal for temperature and pressure measurement has been completed. The entire sensor has been fabricated and tested to see its sensitivity to temperature and pressure changes. The design and optimization of the radiation shielding systems that can effective protect the duel-mode Langasite sensor inside reactor core were demonstrated. To maximize the radiation shielding effectiveness, different types of materials are investigated based upon recent developments of radiation shielding systems including aluminum + Boron carbide and bismuth borosilicate glass B2O3 in addition to tungsten/B4C. New materials based upon metatheses is included as potential shielding to mitigate neutron fluencies. The radiation shielding effectiveness of selected composites are evaluated within a broader neutron spectrum from thermal, epithermal, fast (1 MeV) and 15 MeV neutrons. Performance analysis was also conducted to evaluate the effects of selected composite systems.Aconceptual design was also proposed for the packaging and integration of the radiation shielding system with the sensor, and its applicability within the reactor core was discussed. At end of the project, all components necessary for a complete sensing and monitoring system, including a langasite sensor, electrodes, the TEG harvester, an energy storage device, and power management and transmission electronics were integrated to demonstrate feasibility in powering the sensor. Finally, integration of each component into a full package, and a full demonstration were done.

A detailed three-dimensional thermal and fluid analysis of a vertical dry storage cask with a canister containing 32 high-burnup pressurized water reactor (PWR) spent fuel assemblies for a storage of 50 years was carried out using a CFD simulation. The input decay heat value was calculated based on a Westinghouse 17 x 17 PWR fuel assembly using the well validated package ORIGAMI imbedded in SCALE, with a total heat load of 38.44 kW for year 5 and 10.67 kW for year 55. The temperature dependent and anisotropic thermal properties of the fuel assemblies, filling gas within the canister, and air covering the canister were considered in order to preserve accuracy. A peak temperature of 621.4 K occurred in the upper part of the fuel assemblies for at year 5, deceasing to 423.0 K after 50-year service. The simulation results shed light on the temperature and flow environment within the canister for an operational time of 50 years. Published by Elsevier Ltd.

Monitoring the parameters inside enclosed metal vessels or thick concrete walls as found in dry storage canisters and nuclear reactor vessels is crucial to ensuring safe reactor operation and fuel security. In this paper, two energy harvesters, namely the gamma radiation energy harvester and the thermal energy harvester, were built to power the wireless through-wall and communications for in-situ monitoring of interior conditions in nuclear canisters. The gamma radiation energy harvester was found to have an energy output of 17.8 mW during the first-year canister storage. However, this energy harvester was burdensome, and the performance deteriorates rapidly with time. The thermal energy harvester was thought to be a more practical solution. The power output of the energy harvester was about 93.9 mW in simulation and 46.3 mW in the experiment after 50-years storage in the canister. The power output of this energy harvester can be further scaled by adding TEGs at the cost of larger size.

Monitoring the conditions inside enclosed metal vessels as found in spent fuel canisters and nuclear reactor pressure vessels is crucial to ensuring safe dry cask storage and reactor operation. In this paper two energy harvesters, a gamma radiation energy harvester and a thermal energy harvester, are designed to power wireless through-wall communication and in-situ monitoring of interior conditions in nuclear canisters. Their performance over 50 years of service in the canister is analyzed using radiation and thermal modeling of the canister, and a scaled experiment is performed to validate the designs. The gamma radiation energy harvester was found to have an energy output of 17.8 mW during the first-year of canister storage. However, its power out decreases to less than 1.0 mW after 50-years storage. The thermal energy harvester proved to be more practical with a simulated power output of 93.9 mW and an experimental output of 46.3 mW even after 50-years storage in the canister. Cost-benefit analysis and discussion for both energy harvesters were also given. (C) 2018 Elsevier Ltd. All rights reserved.

This work develops an enhanced Monte Carlo (MC) simulation methodology to predict the impacts of layout-dependent correlated manufacturing variations on the performance of photonics integrated circuits (PICs). First, to enable such performance prediction, we demonstrate a simple method with sub-nanometer accuracy to characterize photonics manufacturing variations, where the width and height for a fabricated waveguide can be extracted from the spectral response of a racetrack resonator. By measuring the spectral responses for a large number of identical resonators spread over a wafer, statistical results for the variations of waveguide width and height can be obtained. Second, we develop models for the layout-dependent enhanced MC simulation. Our models use netlist extraction to transfer physical layouts into circuit simulators. Spatially correlated physical variations across the PICs are simulated on a discrete grid and are mapped to each circuit component, so that the performance for each component can be updated according to its obtained variations, and therefore, circuit simulations take the correlated variations between components into account. The simulation flow and theoretical models for our layout-dependent enhanced MC simulation are detailed in this paper. As examples, several ring-resonator filter circuits are studied using the developed enhanced MC simulation, and statistical results from the simulations can predict both common-mode and differential-mode variations of the circuit performance.

Dedicated sensors are widely used throughout many industries to monitor everyday operations, maintain safety and report performance characteristics. In order to adopt a more sustainable solution, intensive research is being conducted for self-powered sensing. To enable sensors to power themselves, harvesting energy from environmental vibration has been widely studied, however, its overall effectiveness remains questionable due to small vibration amplitudes and thus limited harvestable energy density. This paper addresses the issue by proposing a novel vibration energy harvester in which a metal compliant mechanism frame is used to house both a linear electromagnetic generator and proof mass. Due to the compliant mechanism, the proposed energy harvester is capable of amplifying machine vibration velocity for a dedicated electromagnetic generator, largely increasing the energy density. The harvester prototype is also fabricated and experimentally characterized to verify its effectiveness. When operating at its natural frequency in a low base amplitude, 0.001 in (25.4μm) at 19.4 Hz, during lab tests, the harvester has been shown to produce up to 0.91 V AC open voltage, and a maximum power of 2 mW, amplifying the relative proof mass velocity by approximately 5.4 times. In addition, a mathematical model is created based on the pseudo-rigid-body dynamics and the analysis matches closely with experiments. The proposed harvester was designed using vibration data from nuclear power plants. Further steps for improving such a design are given for broader applications.

Recent design flows for photonic integrated circuits have been able to take advantage of mature capabilities available in electronic design automation such as schematic driven design and sophisticated circuit verification. Furthermore, new photonic integrated circuit simulators that can interface with electrical circuit simulators have been developed. As a result, photonic design flows are rapidly advancing in maturity. An area that still requires development is the statistical analysis of photonic circuits to be able to predict and improve yield, which is particularly challenging because photonic components tend to be large compared to the wavelength which makes them highly sensitive to phase errors. Furthermore, photonic devices tend to have long range spatial correlations in their parameters that cannot be ignored. In this paper, we present two approaches that enable Monte Carlo analysis of photonic integrated circuits, which include the treatment of spatial correlations, and we show how they can be used to predict the circuit yield. Example circuits include passive filters made from cascaded Mach-Zehnder interferometers and transceivers using active ring modulators.

Dedicated, self-powered wireless sensors are widely being studied for use throughout many industries to monitor everyday operations, maintain safety, and report performance characteristics. To enable sensors to power themselves, harvesting energy from machine vibration has been studied, however, its overall effectiveness can be hampered due to small vibration amplitudes and thus limited harvestable energy density. This paper addresses the issue by proposing a novel vibration energy harvester architecture in which a compliant mechanism and proof mass system is used to amplify the vibrational velocity of machine vibration for a linear electromagnetic generator. A prototype has been fabricated and experimentally characterized to verify its effectiveness. When operating at its natural frequency in a low base amplitude, 0.001 inch (25.4 mu m) at 19.4 Hz, during lab tests, the harvester has been shown to produce up to 0.91 V AC open voltage, and a maximum power of 2 mW, amplifying the relative proof mass velocity by approximately 5.4 times. This method of locally increasing the machine vibrational velocity has been shown to be a viable option for increasing the potential power output of an energy harvester. In addition, a mathematical model is created based on pseudorigid-body dynamics and the analysis matches closely with experiments.

The effect of thermal crosstalk in a thermo-optically tuned silicon optical router is assessed using a combination of component level physical simulations and circuit level simulations. By restricting the physical simulation volume to only a small number of components and using fast compact models for circuit-scale simulations, this methodology can be scaled effectively to large switch matrices.

Silicon photonics is nothing new. It has been around for decades, but in recent years, it has gained traction as electronic design challenges increase drastically with their atomic-level limitations. Silicon photonics has made significant advancements during this period, but there are many obstacles without an acceptable level of comfort as seen by the lack of semiconductor community involvement. Apart from a series of technological barriers, such as extreme fabrication sensitivity, inefficient light generation on-chip, etc., there are also certain design challenges. In this chapter, we will discuss the challenges and the opportunities in photonic integrated circuit design software tools, examine existing design flows for photonics design and how these fit different design styles, and review the activities in collaboration and standardization efforts to improve design flows.

A thermoelectric energy harvester composed of two thermoelectric modules, a wicked copper-water heat pipe, and finned heat sinks has been designed, modeled, and tested. The harvester is proposed to power sensor nodes on heating/cooling, steam, or exhaust pipes like these in power stations, chemical plants and vehicle systems. A model to analyze the heat transfer and thermoelectric performance of the energy harvesting system has been developed and validated against experiments. The results show that the model predicts the system power output and temperature response with reasonable accuracy. The model developed in this paper can be adapted for use with general heat sink, heat pipe, and thermoelectric systems. The design, incorporating a heat pipe and two 1.1" by 1.1" Bi2Te3 modules generates 2.25 W +/- 0.13 W power output walla temperature difference of 128 degrees C +/- 1.12 degrees C and source temperature of 246 degrees C +/- 1.9 degrees C, which is more than enough to operate wireless sensors or some actuators. The use of a heat pipe in this design increased the power output by 6 times over conventional designs. Based on the model, further improvement of the power output and energy harvesting efficiency of the system has been suggested by optimizing the number of thermoelectric modules. (C) 2016 Elsevier Ltd. All rights reserved.

Electronic circuit designers commonly start their design process with a schematic, namely an abstract representation of the physical circuit. In integrated photonics on the other hand, it is very common for the design to begin at the physical component level. In order to build large integrated photonic systems, it is crucial to design using a schematic-driven approach. This includes simulations based on schematics, schematic-driven layout, layout versus schematic verification, and post-layout simulations. This paper describes such a design framework implemented using Mentor Graphics and Lumerical Solutions design tools. In addition, we describe challenges in silicon photonics related to manufacturing, and how these can be taken into account in simulations and how these impact circuit performance.

Safety is the most important issue in the development of nuclear energy. This paper reports experimental studies of a thermoelectric energy harvesting system designed for integration in a nuclear power plant capable of performing in radiation rich environments and producing enough power to run wireless sensors meant to increase plant safety. Furthermore, the system, which utilizes wasted heat present in coolant system piping, has the unique ability to provide power in both normal and accidental situations, to run the sensors without the need for external power. Two energy harvesting prototypes were designed utilizing a heat pipe for heat transfer. The first can supply a maximum power of 2.25 W using two Bi2Te3 thermoelectric modules of 2.79cm (1.1") × 2.79 cm (1.1”), in a source temperature near 250 °C. A second design was put forward to extend the application in higher-temperature primary loops, in which one PbTe-Bi2Te3 hybrid TEG module of 5.6cm (2.2") × 5.6 cm (2.2") can provide a power of 3.0 W when the hot side temperature reaches 340 °C. In addition to the energy harvester, wireless communication circuits were developed along with an integrated power management circuit for wireless data transmission. A high intensity gamma radiation experiment was conducted during which each component was irradiated. A total dose of 200 kGy±10% (20M rads) was applied to the first prototype in order to approximate the expected lifetime accumulation for one implemented thermoelectric generator. Results showed that thermoelectric modules used in the prototype had no reduction in voltage output throughout irradiation. Throughout the experiment the harvester system witnessed a small voltage drop in open circuit voltage attributed to a reduction in heat pipe performance from radiation exposure. We also acquired a baseline radiation survivability level for non-hardened, non-shielded electronics of 102 Gy.

We present a novel design methodology for silicon photonic integrated circuits (PICs) that integrates Cadence’s Spectre with Lumerical’s INTERCONNECT. It supports parametric analysis of bidirectional, multi-mode PICs, with electrical feedback.

Electronic circuit designers commonly start their design process with a schematic, namely an abstract representation of the physical circuit. In integrated photonics on the other hand, it is common for the design to begin at the physical component level, and create a layout by connecting components with interconnects. In this paper, we discuss how to create a schematic from the physical layout via netlist extraction, which enables circuit simulations. Post-layout extraction can also be used to predict how fabrication variability and non-uniformity will impact circuit performance. This is based on the component position information, compact models that are parameterized for dimensional variations, and manufacturing variability models such as a simulated wafer thickness map. This final step is critical in understanding how real-world silicon photonic circuits will behave. We present an example based on treating the ring resonator as a circuit. A silicon photonics design kit, as described here, is available for download at http://github. com/lukasc-ubc/SiEPIC_EBeam_PDK.

The thermoelectric generator (TEG) is a distinctive solid-state heat engine with great potential in various scale energy harvesting. Device-level heat transfer coupled with energy conversion makes the accurate analysis of the system very complicate. In this paper, the thermodynamic analysis in a TEG module is carried out to study the influence of the contact layer resistance, Thompson Effect, Joule heat, and thermo-pellet gap heat leakage on the performance of the TEG. All expressions of power output, current, matching load resistant factor, and efficiency of the device are derived and compared with a commercial module. The equations for the simplified model are also given concisely in order to give a full picture of TEG modeling. The research can evaluate the combined influence of all the factors and redress some derivations in the existing models.

We present a vision for photonic circuit simulation within sophisticated EDA-style design flows and the tool development roadmap to achieve it. Our approach aims to deliver highly-usable, predictive capabilities for a variety of use cases, that seamlessly interoperates with 3 rd -party, best-in-class design tools.

We show how scalable photonic circuit design can be achieved with an EDA-style schematic driven design flow combined with a foundry specific PDK, including validated compact models for accurate photonic circuit simulation and verification.

This paper describes design methodologies developed for silicon photonics integrated circuits. The approach presented is inspired by methods employed in the Electronics Design Automation (EDA) community. This is complemented by well established photonic component design tools, compact model synthesis, and optical circuit modelling. A generic silicon photonics design kit, as described here, is available for download at http://www.siepic.ubc.ca/GSiP.