INL Subsurface Wireless Sensor Platform

The Idaho National Laboratory is developing a versatile micro-power sensor interface platform for periodic subsurface sensing of environmental variables important to waste disposal sites such as volumetric moisture, water potential, and temperature. The key characteristics of the platform architecture are that the platform is passive until externally energized—no internal power source is required—and that it communicates with a reader via short-range telemetry—no wires penetrate the subsurface. Other significant attributes include the potential for a long service life and a compact size that makes it well suited for retrofitting existing landfill structures. Functionally, the sensor package is “read” by a short-range induction coil that activates and powers the sensor platform as well as detects the sensor output via a radio frequency signal generated by the onboard programmable interface controller microchip. As a result, the platform has a functional subsurface communication range of approximately 10 to 12 ft. and can only accept sensors that require low power to operate

Finite Element Simulation of Pulsed Remote Field Eddy Current Phenomenon

The remote field eddy current (RFEC) effect was first observed when an alternating current was applied to a coil inside a metallic pipe. It is characterized by the energy released from an excitation coil which propagates twice through the tube/pipe wall under inspection before it reaches the pick-up coils/sensors located 2–3 diameters away from the excitation. This technique is routinely used for metallic tube inspection. Distinguishing features include high and equal sensitivity to both OD and ID defects, independence of phase signals to lift-off, approximately linear signal phase to thickness relationship, no restriction with regard to penetration depth, and detection depending on signal-to-noise ratio only. There are also some disadvantages associated with the RFEC technique, primarily, high power requirements and large separation distances between the excitation and sensor coils

INL Subsurface Wireless Sensor Platform

The Idaho National Laboratory is developing a versatile micro-power sensor interface platform for periodic subsurface sensing of environmental variables important to waste disposal sites such as volumetric moisture, water potential, and temperature. The key characteristics of the platform architecture are that the platform is passive until externally energized --no internal power source is required -- and that it communicates with a "reader" via short-range telemetry - no wires penetrate the subsurface. Other significant attributes include the potential for a long service life and a compact size that makes it well suited for retrofitting existing landfill structures. Functionally, the sensor package is "read" by a short-range induction coil that activates and powers the sensor platform as well as detects the sensor output via a radio frequency signal generated by the onboard programmable interface controller microchip. As a result, the platform has a functional subsurface communication range of approximately 10 to 12 ft. and can only accept sensors that require low power to operate

Inspection of Used Fuel Dry Storage Casks

ABSTRACT The U.S. Nuclear Regulatory Commission (NRC) regulates the storage of used nuclear fuel, which is now and will be increasingly placed in dry storage systems. Since a final disposition pathway is not defined, the fuel is expected to be maintained in dry storage well beyond the time frame originally intended. Due to knowledge gaps regarding the viability of current dry storage systems for long term use, efforts are underway to acquire the technical knowledge and tools required to understand the issues and verify the integrity of the dry storage system components. This report summarizes the initial efforts performed by researchers at Idaho National Laboratory and Argonne National Laboratory to identify and evaluate approaches to in-situ inspection dry storage casks. This task is complicated by the design of the current storage systems that severely restrict access to the casks

Eddy Current Examination of Spent Nuclear Fuel Canister Closure Welds

The National Spent Nuclear Fuel Program (NSNFP) has developed standardized DOE SNF canisters for handling and interim storage of SNF at various DOE sites as well as SNF transport to and SNF handling and disposal at the repository. The final closure weld of the canister will be produced remotely in a hot cell after loading and must meet American Society of Mechanical Engineers (ASME) Section III, Division 3 code requirements thereby requiring volumetric and surface nondestructive evaluation to verify integrity. This paper discusses the use of eddy current testing (ET) to perform surface examination of the completed welds and repair cavities. Descriptions of integrated remote welding/inspection system and how the equipment is intended function will also be discussed

The Effects of Stress Mitigation on Nondestructive Examination

Ultrasonic volumetric and eddy current and visual profile surface inspections of the completed weld securing the outer lid of the Yucca Mountain waste package are required after stress mitigation. However, the technique implemented may affect the ability of the different evaluation techniques to properly characterize the completed weld. An evaluation was performed to determine the extent the nondestructive evaluation techniques are affected by two candidate mitigation processes: controlled plasticity burnishing and laser peening. This report describes the work performed and summarizes the results

Ultrasonic Phased Array Implementation of the Inside Diameter Creeping Wave Sizing Method

This paper describes a technique for implementing the ultrasonic inside diameter (ID) creeping wave technique for detection and sizing ID connected defects using a phased array ultrasonic system. The technique uses multiple focal laws to produce the examination modes. The first focal law is designed to create a shear wave nominally at the critical angle for mode conversion to a longitudinal wave at the ID of a part, thus creating a creeping wave. This focal law is focused at the ID to improve sensitivity. The rest of the laws are designed to create tandem sound paths that progress up a vertical surface directly above the focal point of the creeping wave generation point. When a defect on the inner surface is detected with the creeping wave, the height of the defect can be measured from the response of a set of tandem laws without readjusting the position of the probe. Results from standard one-inch long notches of varying depths are presented

Microstructure, Processing, Performance Relationships for High Temperature Coatings

HVOF coating have shown high resistance to corrosion in fossil energy applications and it is generally accepted that mechanical failure, e.g. cracking or spalling, ultimately will determine coating lifetime. The high velocity oxygen-fuel method (HVOF) of applying coatings is one of the most commercially viable and allows the control of various parameters including powder particle velocity and temperature which influence coating properties, such as residual stress, bond coat strength and microstructure. Methods of assessing the mechanical durability of coatings are being developed in order to explore the relationship between HVOF spraying parameters and the mechanical properties of the coating and coating bond strength. The room temperature mechanical strength, as well as the resistance of the coating to cracking/spalling during thermal transients, is of considerable importance. Eddy current, acoustic emission and thermal imaging methods are being developed to detect coating failure during thermal cycling tests and room temperature tensile tests. Preliminary results on coating failure of HVOF FeAl coatings on carbon steel, as detected by eddy current measurements during thermal cycling, are presented. The influence of HVOF coating parameters of iron aluminides - applied to more relevant structural steels, like 316 SS and Grade 91 steel, - on coating durability will be explored once reliable methods for identification of coating failure have been developed

Nondestructive Evaluation of Nuclear-Grade Graphite

Nondestructive Evaluation of Nuclear Grade Graphite Dennis C. Kunerth and Timothy R. McJunkin Idaho National Laboratory Idaho Falls, ID, 83415 This paper discusses the nondestructive evaluation of nuclear grade graphite performed at the Idaho National Laboratory. Graphite is a composite material highly dependent on the base material and manufacturing methods. As a result, material variations are expected within individual billets as well billet to billet and lot to lot. Several methods of evaluating the material have been explored. Particular technologies each provide a subset of information about the material. This paper focuses on techniques that are applicable to in-service inspection of nuclear energy plant components. Eddy current examination of the available surfaces provides information on potential near surface structural defects and although limited, ultrasonics can be utilized in conventional volumetric inspection. Material condition (e.g. micro-cracking and porosity induced by radiation and stress) can be derived from backscatter or acousto-ultrasound (AU) methods. Novel approaches utilizing phased array ultrasonics have been attempted to expand the abilities of AU techniques. By combining variable placement of apertures, angle and depth of focus, the techniques provide the potential to obtain parameters at various depths in the material. Initial results of the study and possible procedures for application of the techniques are discussed

Nondestructive evaluation of nuclear-grade graphite

Nondestructive Evaluation of Nuclear Grade Graphite Dennis C. Kunerth and Timothy R. McJunkin Idaho National Laboratory Idaho Falls, ID, 83415 This paper discusses the nondestructive evaluation of nuclear grade graphite performed at the Idaho National Laboratory. Graphite is a composite material highly dependent on the base material and manufacturing methods. As a result, material variations are expected within individual billets as well billet to billet and lot to lot. Several methods of evaluating the material have been explored. Particular technologies each provide a subset of information about the material. This paper focuses on techniques that are applicable to in-service inspection of nuclear energy plant components. Eddy current examination of the available surfaces provides information on potential near surface structural defects and although limited, ultrasonics can be utilized in conventional volumetric inspection. Material condition (e.g. micro-cracking and porosity induced by radiation and stress) can be derived from backscatter or acousto-ultrasound (AU) methods. Novel approaches utilizing phased array ultrasonics have been attempted to expand the abilities of AU techniques. By combining variable placement of apertures, angle and depth of focus, the techniques provide the potential to obtain parameters at various depths in the material. Initial results of the study and possible procedures for application of the techniques are discussed