Analysis of Radiation Damage in Electronics of Unmanned Aerial and Ground Robotic Platforms

• Radiation measurements are necessary for a routine monitoring of nuclear facilities and during emergencies, such as the Fukushima Daiichi nuclear power plant accident • Robotic platforms are utilized to carry radiation sensors to allow for remote sensing and sampling operations • Unmanned Aerial Systems (UAS) and Unmanned Ground Vehicle (UGV) • Robots might be exposed to the ionizing radiation (high dose levels are possible) • Irradiation causes defects in devices and components leading to malfunctions and limiting the robot capabilities, decreasing its operational time • The goal is to complete scheduled tasks while the robot is being irradiated • To achieve this goal, electronic components should be shielded and radiation hardened • Radiation damage in materials is characterized by the displacement per atom (DPA) • Monte Carlo code FLUKA was used to calculate the DPA values in electronic component

Applied Analysis of Ionic Polymer Metal-Composite Actuators

IPMC is a type of smart material called an electroactive polymer Consists of an ionic polymer such as Nafion or Flemion and a conducive metal such as platinum or gold COMSOL multi-physics simulations accurately model the experimental displacement results Optimization performed using the multi-physics model to find the maximum deflection, force, and twisting Using the closed loop control system accurate IPMC tip location can be achieved This control system has been extended to function using a computer mouse as an inpu

Experimental Dual-mode Control of a Flexible Robotic Arm

This paper focuses on the implementation of a dual-mode controller for the maneuver of a single link flexible robotic arm. The joint angle trajectory tracking is accomplished by a proportional and derivative PD and a feedforward controller. Based on the pole placement technique, a linear stabilizer is designed for elastic mode stabilization. The stabilizer is switched on when the trajectory reaches the vicinity of the terminal state, and the effect of . switching time on arm vibration is investigated. An optical deflection sensor is used for on-line measurements of elastic deflections, and also used for the prediction of the static deflection of the arm in the target position. The robustness of the linear stabilizer at varying payloads is presented

Gamma Ray Measurements Using Unmanned Aerial Systems

Gamma ray measurements involved in monitoring technologies of field conditions are of vital importance for environmental safety and radiation protection. This chapter addresses the method of cooperative gamma sensing using multiple unmanned aerial systems. Section 1 provides an introduction. The design of semiconductor and scintillation gamma ray sensors integrated into aerial robotic platforms is discussed in Section 2, along with the fusion of time-stamped radiation data with position information using the real-time kinematic positioning technique. Section 3 addresses the multirobot contour mapping of radiation fields. Computer simulation of radiation contour mapping is discussed in Section 4. Experimental verification of the contour mapping and source-seeking algorithm is described in Section 5. Section 6 summarizes results of the project

Decoupling and Disturbance Rejection Control for Target Circulation

In 1998, the Institute of Physics and Power Engineering (IPPE) and Experimental and Development Organization “Gidropress” in Russia, began the design and construction of a prototype lead-bismuth eutectic (LBE) accelerator target, the Target Complex 1 (TC-1), under the International Science and Technology Center (ISTC) project #559 (“Pilot Flow Lead-Bismuth Target of 1 MW Power for Accelerator Driven Systems”) in support of the international efforts to develop accelerator-driven spallation systems for nuclear transmutation and other applications. During the thermal and engineering test of the TC-1 in 2005 at UNLV, it was observed that the existing control algorithm led to a very slow convergence to the target temperature setting and also showed unstable oscillatory behavior. The original algorithm was not robust enough to handle the complicated heating system of the TC-1, where nine heating zones (elements) are compacted in one tight container. This interaction and coupling between each heating zone, as well as a heat disturbance from a low efficiency electromagnetic (EM) pump caused the overall temperature control system to be complex and nonlinear. The objective of the proposed research was to study the coupling effect between each heating zone, and to improve the overall temperature control system of the TC-1 loop. In addition to the temperature control algorithm modification, a 24-hour automatic monitoring system of the EM pump was developed for robust and safe operation of the loop

Developing a Sensing System for the Measurement of Oxygen Concentration in Liquid Pb-Bi Eutectic

Lead-bismuth eutectic (LBE) is a candidate as a spallation target in sub-critical transmutation systems and as a coolant in nuclear programs. One of the primary concerns with LBE systems is the corrosion of stainless steel, the primary structural material used in nuclear systems. To mitigate this problem, trace levels of oxygen can be introduced into the system, causing the formation of a protective oxide layer at the interface between the LBE and steel. To protect the steel components, this oxide layer must be properly maintained. However, too much oxygen will produce unwanted oxide precipitation within the coolant and elsewhere in the system. With the current generation LBE systems, the stability of the oxide layer on the internal components is maintained through controlling the temperature of the system and the dissolved oxygen concentration in the coolant. Controlling these two operating parameters is the key to operating LBE systems and minimizing corrosion. While the temperature of the system is easy to measure, the concentration of dissolved oxygen in the LBE is more complicated. Yttria-stabilized zirconia (YSZ) solid-electrolyte oxygen sensing systems are currently employed by Los Alamos National Laboratory (LANL) scientists to measure oxygen levels in the Delta Loop, an engineering-scale LBE experimental system. By measuring the voltage difference across the YSZ sensor, the oxygen concentration in test solutions can be determined relative to that in the reference solutions (the potentiometric method). The theoretical model for calculating oxygen concentration based on voltage measurements from YSZ sensors in static conditions is well understood. The real world performance of these systems, however, is less predictable. The primary goal of this research project is to examine the major factors impacting the performance of YSZ oxygen sensing systems. The research effort will serve to fill the gaps in the current sensor calibration/validation work and further the development of new sensors for oxygen concentration measurement in a nuclear environment. Ultimately, acquired data will lead to the full implementation of the instrumentation in the system. Through this work, the research group will also generate the calibration curves for the YSZ sensors over various temperature ranges

Developing a Sensing System for the Measurement of Oxygen Concentration in Liquid Pb-Bi Eutectic: Quarterly Progress Report (May 01 – July 31, 2002)

Accurate measurement of the oxygen concentration in liquid Lead-Bismuth Eutectic (LBE) cooling system is critical in the active control of the corrosion at the interface between LBE and the stainless steel of transport tubes. Currently, LANL (Los Alamos National Laboratory) scientists have employed an automobile-style YSZ (Yttria Stabilized Zirconia) oxygen sensor unit to measure oxygen levels in an engineeringscaled LBE test system. Although the theoretical model for calculating oxygen concentration based on voltage measurement of YSZ sensor in static conditions is well understood, there is an urgent and strong need to obtain a complete set of calibration curves for YSZ sensor systems under various temperature and flow conditions in LBE environment due to device and material imperfectness as well as the unwanted mobility of the electrons at high temperatures. This research project, therefore, is aimed at filling the gap of sensor calibration/validation and further developing new sensors for oxygen concentration measurement in a nuclear environment

Developing A Sensing System for the Measurement of Oxygen Concentration in Liquid Pb-Bi Eutectic: Quarterly Progress Report (Nov. 01 – Jan. 31, 2002)

The design of the new apparatus for oxygen measurement/calibration has been completed. This new apparatus shall be of great importance for the UNLV researchers to conduct the research work in the campus

Developing A Sensing System for the Measurement of Oxygen Concentration in Liquid Pb-Bi Eutectic: Quarterly Progress Report (Aug. 01 – Oct. 31, 2002)

After two month intensive work in LANL, some preliminary sensor calibration curves have been obtained. Further data analysis shall be performed to assess the theoretical and measured data. Also, a new experimental apparatus shall be designed and located in UNLV to continue the left work. Technical Progress: • A set of calibration curves of voltage vs. temperature ranging from 3000C to 5000C under various oxygen concentrations in liquid LBE for the YSZ oxygen sensor has been obtained and has been reported in one paper. • A meeting with LBE committee and other faculty members in AAA projects was organized to discuss our new experimental apparatus design. • We have identified the major components/parts to be incorporated in our sensor experimental apparatus, and we have finalized the geometries of some of the parts. This newly-designed system shall be accommodated in HRC center. • We started to use FEMLAB free version to do simulations for oxygen concentration distributions in our setup due to stirring

Calibration of YSZ Sensors for the Measurement of Oxygen Concentration in Liquid Pb-Bi Eutectic

Although liquid lead-bismuth eutectic (LBE) is a good candidate for coolant in the subcritical transmutation blanket, it is known to be corrosive to stainless steel, the material of the carrying tubes and containers. Such longterm corrosion problem can be prevented by producing and maintaining a protective oxide layer on the exposed surface of stainless steel. For this purpose, it is required to accurately control the concentration of oxygen dissolved in LBE. Currently, YSZ (Yttria Stabilized Zirconia) oxygen sensors, based on an existing automotive oxygen sensor, with molten bismuth saturated with oxygen as the reference, have been selected for oxygen-concentration measurement. The oxygen concentration difference across the solid electrolyte and the resultant oxygen ion conduction inside the electrolyte establishes an electromagnetic force that is used to measure the ppb level concentration of oxygen dissolved in liquid LBE. A set of calibration curves of voltage vs. temperature ranging from 300 0C to 500 0C under various oxygen concentrations in liquid LBE for the YSZ oxygen sensor has been obtained and is presented in this paper. Although the current calibration strategy using the direct injection of hydrogen and oxygen is still inadequate to determine the oxygen concentration in the system, we have found a good candidate for our purpose, which is varying hydrogen to water steam ratio in the system